energy saving

Notes
3.1 Electrical Motors

Chapter - 3
Electrical Utilities

Electric motors convert electrical energy into mechanical energy. There are basically 3 types of motors: 1. 2. 3. AC Induction Motors AC Synchronous Motors DC Motors

The detailed classification of electric motors is given below :
Electric Motors D.C. Motors Brushless D.C Brush D.C A.C. Motors Single Phase Three phase/polyphase Shaded pole Reluctance Split Phase Induction Squirrel cage Slip ring Synchronous Linear Induction
Synchromous

Shunt Wound
Separately Excited

Series wound Compound wound

Electric motors are inherently very efficient. Their efficiencies vary from 85% to 95% for motors of sizes ranging from 10 HP to 500 HP. It is still possible to improve the efficiency of these motors by 1 to 4% by improving the design of motor . 3.1.1 a) Power Consumption in Motors Efficiency and Power Factor

The power consumed by a 3-phase AC motor is given by Power Input = 3 x Voltage x Current x Power Factor

If the voltage is in Volts and the current in Amperes, the power will be in Watts (w). The power in Watts divided by 1000 is kilowatts (kW). The power input to the motor varies with the output shaft load.
Electrical Power input (kW) = Mechanical Shaft Output x 100 Motor Efficiency (%)

Electrical Power input (KVA) =

Power Input (kW) x 100 Power Factor

Variations of motor efficiency and power factor with load are shown in Fig. 3.1 Torque speed and current speed characteristics of different types of rotors are shown in Fig.3.2. The load vs full load current is shown in Fig. 3.3. The following may be noted from these curves.
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1. 2. 3. 4. 5. 6. 7.

The motor efficiency remains almost constant upto 50% load. Below 50% load, the efficiency drops significantly till it reaches zero at 0% load. At a particular operating voltage and shaft load, the motor efficiency is fixed by design, it cannot be changed externally. The power factor reduces with load. At no load the p.f. is in the range of 0.05 to 0.2 depending on size of the motor. At no load, the power consumption is only about 5% or so, just sufficient to supply the iron loss, friction and windage losses. The no load current is however of the order of 30% to 50% of full load current. This amount of magnetizing current is required because of air gap in the motor. The starting torque is 100% to 200%, the maximum torque is 200% to 300% of rated torque. The starting current remains at a high value of more than 500% of rated current upto 75% to 80% speed and then drops sharply.
100 90 80 1.0 0.9 0.8 0.7 0.6 0.5

100 90 80 % Full Load Current 70 60 50 40 30 20 25 50 75 100
LARGE MOTOR (25 HP & ABOVE) SMALL MOTOR (BELOW 25 HP)

% Load (Shaft Power)

Fig 3.3 : Current v/s Load 3.1.2 Importance of Motor Running Cost-Life Cycle Costs

% Efficiency & Power Factor

70 60 50

%

30 20 10 0 0 25 50 75

0.3 0.2 0.1

pf

40

0.4

Motors can run without problems for 20 years or more with good protection and routine maintenance. However, if they are running inefficiently, it is worthwhile replacing them as running costs are much more than first costs. Motors can be considered as consumable items and not capital items, considering the current energy prices. The importance of running cost can be seen from Table 3.1. The following points may be noted: Table 3.1 : Importance of Motor Running Cost

100

% Load j

Motor Rating (kW)
Low Efficiency

7.5
High Efficiency Low Efficiency

37
High Efficiency

Efficiency

+ Power Factor

Fig 3.1 : Load vs Efficiency & Power Factor.

Efficiency Power Input (kW) Running Hours Energy Input (kWh) Running Cost (Rs.) per Annum (@Rs. 4.00/ kWh) Running Cost (Rs.) for 10 years
First Cost (Rs.) First Cost as % of Running cost for 10 years

0.86 8.72 6000 52320 209280

0.88 8.52 6000 51120 204480

0.92 40.22 6000 241320 965280

0.93 39.78 6000 238680 954720

2092800 12000 0.57

2044800 12000 0.59

9652800 70000 0.72

9547200 70000 0.73

1.

2. Fig 3.2 : Performance with Tee Bar, Deep Bar, Trapezoidal and Double Cage Rotors
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Even a small motor of 7.5 kW consumes, at full load, electricity worth Rs. 20 lakh in 10 years. Similarly, a 37 kW motor consumes about Rs. 1 crore worth of electricity in 10 years. The first cost is only around 1% of the running cost for 10 years, hence running costs are predominant in life cycle costing.

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3. 4.

Even a small difference in efficiency can make a significant difference in running cost. When economically justified, motors may be replaced, even if these have been recently installed. Energy Saving Opportunities in Motors
1. 2. 3. 4. 5. 6. 7. 8. 9. Current (star) Current (Delta) Power factor (star) Power factor (Delta) Efficiency (star) Efficiency (Delta) Speed (star) Speed (Delta) Change overline

3.1.3

The main energy saving opportunities in motors can be summarized as follows: a) b) c) d) e) f) g) h) Stopping idle or redundant running of motors. Matching motor with the driven load (sizing of motors) Operation of under-loaded Delta connected motor in Star connection. Soft starters with Energy Saving Features. Use of Variable Frequency Drives (VFDs) Improving drive transmission efficiency Use of high efficiency motors Improvement in motor drive systems

Oversized Motors lead to the following problems: 1. 2. 3. 4. 5. 6. 7. 8. Higher investment cost due to larger size. Higher running cost due to decrease in efficiency. Higher maximum demand due to poor power factor. Higher cable losses and demand charges. Higher switchgear cost. Higher space requirement. Higher installation cost. Higher rewinding cost (in case of motor burnout) Fig. 3.4 : Motor Performance in Delta and Star Connections The following suggestions are made : 1. If a motor is oversized and continuously loaded below 30% of its rated shaft load, the motor can be permanently connected in Star. 2. If the motor is normally loaded below 30% but has a high starting torque requirement, then the motor can be started with a suitable starter and, after overcoming the starting inertia, be automatically switched from Delta to Star, using timer control or current sensing. If the load is below 30% most of the time, but if the load exceeds 50% sometimes, automatic Star-Delta changeover Switches (based on current or load sensing) can be used. But, if the changeover is very frequent the contactors would get worn out and the savings achieved may get neutralised by the cost of frequent contactor replacements. 3. If the motor is nearly always operating above 30% of the rated load and sometimes runs below 30% load, a careful analysis is required before installing any arrangement for operation in star connection at light loads. Case Study 1: ‘Delta' to 'Star' connection in Vegetable Oil Works Brief A 25 hp/18.5 kW motor was driving a cooling water circulation pump. The motor was 30% loaded. It was decided to connect the delta connected motor in star. The electrical measurement before & after connection of motor from 'delta' to 'star' is given below:
Parameters Before Implementation (Delta) 415 18.5 0.5 6.72 1469 After Implementation (Star) 415 9.5 0.87 5.96 1454 Saving / Improvement 9.0 0.37 0.76

Table 3.2 Shows the effects of oversized motors on the energy bill and investment

Table - 3.2 : Increased Costs due to Oversized Motors
Motor Rating (kW) Motor Load Requirement (kW) Motor Efficiency % Input Power (kW) Input Energy (kWh) (for 6000 hrs/ annum) Motor Power Factor Input KVA Energy Difference (kWh) Increase in Running Cost (Rs.) Investment (Rs.) Increase in Investment (Rs.) 15 15 89 16.85 101100 0.89 18.93 25000 30 15 89 16.85 101100 0.75 22.44 55000 30000 55 15 84 17.85 107100 0.50 35.70 6000 24000 95000 70000

Voltage (V) Current (A) Power Factor Power Input (kW) Speed (rpm)

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Energy Saving Energy Savings Annual Saving Investment Payback Period : : : : 0.76 kW i.e. 11.3% 6080 kWh Rs.5000 10 months

Energy Saving Annual savings Annual saving Investment Payback period : : : : 1,16,000 kWh Rs. 0.47 Million Rs. 0.5 Million 13 months

Case Study 2: Use of Soft Starter to Facilitate Large Motor Starting with Power Supply from Captive D.G. Set Brief Measurements made in a continuous chemical process plant, where a soft starter was introduced to reduce the starting kick when the motor is started on D.G. set, are high-lighted below : Application Motor Details Starting Using Star/Delta Starter Initial Starting kick Maximum Starting Current Continuous Current Starting With Soft Starter : Settings Starting Current Kick : Current Limit - 200% ; Ramp Time - 30 seconds : 685 A which Reduces to 155 A in 30 seconds : 1800 A for 2 Sec. (Direct) : 480 A (star) / 536 A (delta) : 278 A : 250 hp Air Compressor : 250 hp, 415 V, 3-Phase, 1500 rpm, 313 A

Case Study 4: High Efficiency Gear in Place of Low Efficiency Gear (for a Reactor with Worm Gear ) Energy Saving Parameter Motor Rating (kW) Actual Motor Input (kW) Case Study 5: Brief The Ring Frame motor rating was 40 kW. A standard efficiency motor was compared with an energy efficient motor as given in table below: Energy Saving Standard Motor vs EE Motor Description Motor rating, kW Efficiency % Energy consumed, kWh/doff Standard Energy Efficient (Low Eff) Motor (EE) Motor 40 92 96.22 44 2.187 40 94.5 92.54 44.5 2.080 9564 5 Low efficiency gear 7.5 3.75 3.75 Worm gear 3.75 3.0 3.0 Saving/Improvement 3.75 0.75 0.75

Use of High Efficiency Motors in a Textile Plant

Benefits : Starting current kick reduced by about 60%. Any dip in voltage at the main busbar of DG Set is reduced. The expenditure on maintenance of the motor and the attached mechanical load is also reduced. Case Study 3 : VFD for Cooling Tower Pump in a Chemical Plant Brief This is a case study from a chemical plant manufacturing resins, used for manufacturing paints. A cooling tower with a 125 HP pump was used for process cooling applications. In the existing system, flow variation was through closing/opening valves at the end use points. Also, in the existing system, the return water line of the cooling tower was throttled to control the flow. After installation of an inverter to control the motor speed, this valve was fully opened, thus eliminating the throttling losses. Motor Rating : 125 hp, 415 V, 170A, 2975 rpm.

Weight of yarn per doff Specific energy consumption, kWh/kg yarn Annual electricity saving, kWh Pay back period on extra cost of EE motor, months

Valve position 20% open Fully open Power Saving

Power consumption 53.5 kW 40 kW 13.5 kW
80 81

Table shows comparative data of super efficient motors developed by one manufacturer. Super Efficient Motor
Standard Motor Output Frame Size Supply System RPM Efficiency Fan Ambient Taking annual running hours Input kW at full load Input kW difference Unit Rate (Rs/kWh.) Annual Savings Net Unit Price (Rs.) Price difference Payback 15 kW 160 L 415 V +_ 6%; 50 Hz V +_ 3% 1445 89% Plastic 40 ° C 7165 16.85 Super Efficient Motor 15 kW 160 L 415 V +_ 10%; 50 Hz V +_ 5% 1475 93% C.I 50 ° C 7165 16.13 0.72 4 20,635 32200 10,260 19 months

Energy Efficiency Estimates for Emerging Motor Technologies Table 3.3 : Energy Efficiency Estimates for Emerging Motor Technologies Technology New Motors Superconductor Copper Rotor Switched Reluctance Permanent Magnet Written Pole Controls MagnaDrive Up to 60 Savings are great compared to non- ASDs. Compared to ASDs (Ajustable speed drive )energy savings will be less. Savings are great compared to non -ASDs. Compared to ASDs energy savings will be less. Savings are compared to conventional ASDs 2 to 10 1 to 3 3 5 to 10 3 to 4 Higher efficiencies at partial load 5% has been reported Energy Savings (%) Notes

21940 -

PAYBACK drive 3.1.4 Emerging New Motor Systems Advanced ASDs

Up to 60

Emerging motor system improvements can be categorized into the following three areas of development opportunities: 1. Upgrades to the motors themselves, for example:

2

(Source : LBNL :Energy Efficient Techologies for Industries)

• • • • • •

super conductive motors permanent magnet motors copper rotor motors switched reluctance (SR) drives written pole motors very low loss magnetic steels

3.2

Electric Furnaces

2. System design optimization and management, such as: • • • end use efficiency improvements use of premium lubricants advanced system design and management tools

3. Controls on existing systems, for example: • • • multi-master controls on compressors sensor based controls advanced adjustable speed drives with improvements like regenerative braking, active power factor correction, better torque/speed control. Potential Energy Savings

Electricity is a very clean but costly fuel for heating and melting applications. There are number of advantages in electricity use like improved product quality due to absence of fuel impurities, excellent power control, clean environment (pollution is transferred to central power station) and high efficiency at end use point. But since conversion efficiency of fuel to electricity is only 35% at the power station, the overall efficiency from fuel to end use heating is likely to be 15 to 25%. Hence keeping the overall energy scenario in view, electricity should be used for only special heating applications. Fuel should be used directly to the extent possible. For many conventional heating applications like billet heating and heat treatment, alternate fuels, especially natural gas where available, must be considered. Many companies have changed over from electric heating to heating by other fuels to reduce costs.(However for Induction and Arc Furnances no alternatives are presently available ) Table 3.4 gives the inter-fuel substitution.

3.1.5

Primary specific electrical energy savings for particular motor applications are summarized in Table 3.3.
82 83

Table - 3.4 : Interfuel Substitution : Cost of Alternative Fuels
Energy Source Coal Oil Natural Gas Electricity Cost Rs. 2000/MT Rs. 20/Kg Rs. 8/Nm3 Rs. 4.50/kWh Heat Value 4000 kCal/Kg. 10000 kCal/Kg. 9000 kCal/Nm3 860 kCal/kWh Cost Per 1000 kCal Rs. 0.50 Rs. 2.00 Rs. 0.88 Rs. 5.23

Energy Balance Input Energy Useful Heat Coil I R Radiation Losses Conduction Losses Other Unaccounted
2

Energy Percentage (kWh/tonne) (%) 660 380 130 97.5 34 18.5 100 58.5 20 15 5.2 1.3

Electricity is used in arc furnaces, induction furnaces, heat treatment furnaces, billet heaters, ovens, infrared heaters, etc. Case Study 6 : Replacement of Electric Oven by Gas Fired Oven in an Engineering Industry Brief Electrical Oven Existing Oven : 18 kW Rating LPG Fired Oven Cost of Electricity / hr : 0.11 kW X Rs. 5.00 = Rs. 0.55 (For Auxillaries) Cost of Electricity/hr : 18 kW x Rs. 5= Rs. 90 Cost of LPG/hr : 1.55 Kg x Rs. 25 = Rs. 38.75 Total Running Cost/hr : Rs. 90.00 Total Running Cost / hr = Rs. 39.30

Table-3.6 : Heat Balance of a Heat Treatment Furnaces (Bell Type)
Energy Input Heat In Charge Surface Heat Losses Energy Soaking Heating Outer Bell Inertia Loss Inner Bell Inertia Loss Unaccounted Loss 204.00 kWh 136.10 kWh 250.90 kWh 44.50 kWh 20.25 kWh 822.75 kWh 167.00 kWh

Table-3.7 : Heat Balance in the Arc Furnace
kWh/Liquid Metal Tonne Steel Plant 1: 170 T Furnace Energy Input Electrical Energy Carbon Combustion Other Chemical Reactions (exothermic) Combustion of Graphite Electrodes Total Energy Output Useful Heat in Liquid Metal Exhaust Gases Sensible Heat in Slag Electrical Losses Losses During Operation Conduction, Radiation Heat Losses ---Electrodes Unaccounted Losses Total 426 126 70 48 670 392 104 57 47 40 12 18 670 682 126 70 64 942 426 120 76 60 170 60 12 18 942 Steel Plant 2 : 30 T Furnace

Savings per Hour Annual Savings: Cost of LPG Fired Oven Payback Period

= 90.00 - 39.30 = Rs. 50.70 (56%) = Rs. 50.70 x 24 hours x 25 Days x 12 = Rs. 3,65,040 Rs. 63,000 3 Months

3.2.1 Heat Balance and Energy Saving Opportunities In order to estimate the efficiency of furnaces and also to identify major losses, a heat balance is useful. A heat balance gives information on the energy input, useful energy and major losses. Table -3.5 : Energy Balance of Coreless Induction Furnaces Material Crucible Capacity Production Capacity Power Volt : : : : : Grey Iron 3200 Kg 1600 kg/hr. 733 kW 968 volts

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Table - 3.8 : Energy Balance of a Continuous furnace (Heat treatment furnace conveyor system) Energy Balance Total Energy Input per hour Losses Through Insulation Losses in Cooling Zone Losses Due to Conveyor Useful Heat Unaccounted Losses* Energy (kWh) 37.4 3.8 5 8.6 10 10 Percentage 100 10 13.0 23 27 27

Energy Saving Annual energy saving Investment Payback period : 30,000 kWh : Rs.61,000/: 13 months

3.2.2 Energy Savings by Operational Features a) Operate at full power and capacity as far as possible to get as high a utilization rate as possible. Poor capacity utilization of electric furnaces cause a large wastage of energy. Holding periods can be kept to a minimum. Separate holding furnaces can sometimes be useful. b) Minimise tapping time and frequency to reduce radiation losses and to reduce operation at low power levels. c) Charging system should be such that charging time and frequency are minimised. Possibility of charge compacting and preheating can be explored. d) Molten metal handling and transfer system including ladles can be designed in such a fashion that transfer time and loss in temperature are minimised. Ladle preheating system lead to savings. Well insulated ladles are also necessary. e) Opening of furnace lids, slagging door etc. must be minimised. f) For heat treatment furnaces, production can be so planned that once a furnace is started, it can be utilised continuously, otherwise a lot of energy is wasted in heating the furnace itself. Capacity utilisation is also very important. g) For many heat treatment applications, it may be worthwhile collecting jobs so that full capacity utilisation is achieved. h) Weight of jigs and fixtures for heat treatments should be minimised. i) Surface temperature may be kept at 45oC to 60oC for heat treatment furnaces to reduce radiation losses. j) Process parameters, like heat treatment cycle time and temperatures, have to be checked. Case Study 8 : Electrical Energy Conservation in a Foundry through operational improvement . Brief The plant is equipped to produce about 350 tonnes of Malleable Iron and S.G. Iron Castings per month. Steel scrap is melted in two 4 tonne / 1150 KVA mains frequency furnaces. The product mix consists of a large number of relatively low and medium weight castings. Moulds are made on automatic moulding machines (Pneumatic). The castings are shot blasted, annealed in electric furnaces (600 kW). Fettling and grinding also uses pneumatic tools. These are fed by two compressors of 93 kW each, working one at a time. The present production level is around 220 Tonnes / month. Energy consumption is about 700,000 kWh/month with a maximum demand of around 2700 kVA. Approximate percent consumption of major equipments are given in the Table below.

* Mostly due to convective heat loss due to cold air ingress Case Study 7 : Replacement of an Inefficient, Oversized Oven Brief In a fuse gear industry, the major energy consuming equipment was an oven used for drying ink on ceramic parts and softening of brass components. During the energy audit, some measures suggested to reduce the energy consumption were; a) Reduction of internal volume of the oven to match the basket size. b) Proper sealing of the door to reduce the heat loss. c) Repair of the rear wall of the oven, which had developed cracks, to reduce heat loss. d) Reduction of weight of basket from 30 kg to 10 Kg. e) Use of ceramic fibre insulation in place of fire bricks to reduce starting time and reduce thermal inertia. It was decided to replace the 28 kW oven with a smaller 12 kW oven. The important difference between the old oven and the new oven are highlighted in Table below. Comparison of Performance of Old and New Ovens

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% Distribution Among Major Loads On A Typical Day
Total load 100 Melting Furnaces 60 Annealing furnaces 17.14 Compressors 11.48 Sand Plant 2.55 Other Loads 6.52 Lighting 2.28

Case Study 10: Modification Annealing Ovens in a cable manufacturing industry Brief A cable manufacturing industry, has several annealing ovens, which account for a significant portion of the electricity consumption. A 317 kW oven is used for annealing aluminum conductor in large drums. The oven was large for the jobs being handled. It was redesigned for the job, cutting ceiling height and the insulation was changed to ceramic fibre. The observations are as follows :
Parameters Before Implementation Energy Consumption (kWh) Time needed (hrs.) (5 Tonne charge) Production (Charges per day) 3.0 5.0 1930 8.5 After Implementation 500 3.5 Savings/Improvement

% of Total load

Energy saving was achieved through operational improvement like compacting the scrap and loading it with crane, closing the furnace lid, shutting off the ventilation fans for capacitor cooling during favorable ambient conditions etc. Energy Saving
Parameter SEC (kWh / T) Charging time (hrs.) Annual Saving (kWh) Radiation loss (kWh/day) Ventilator fan for capacitors (HP) Before Implementation 900 10 500 15 After Implementation 700 4 NIL ( - ) 200 (-)6 ( - ) 1,22,070 ( - ) 1,00,000 ( - ) 30,000 kWh/annum Saving/Improvement

( - ) 1430 ( - ) 5.0 (+ ) 2.0

Energy saving Annual Savings Investment Payback period 3.3 Compressed Air System Compressed air is one of the most expensive utilities in manufacturing facilities. First used more than a century ago in pneumatic drills for mining, compressed air has now become an indispensable and a productivity improvement tool for a number of applications ranging from air powered hand held tools to advanced pneumatic robotics. Cost of energy in the compressed air is at least 5 times that of electricity. The energy content in compressed air is further reduced by pressure drop in distribution systems, leakage etc. as shown in fig.3.5. Hence it is important to manage generation, distribution and utilisation of compressed air from energy efficiency viewpoint. : Rs. 1.2 Million : Rs. 0.25 Million : 3 months

Case Study 9: Replacement of inefficient arc furnace with induction furnace Brief Background : A leading automobile components casting foundry had two indirect arc furnaces of capacity 30kg and 80kg respectively. These furnaces were used for producing specialized automobile components. Smaller capacities of the existing furnace meant the number of melting batches was high and correspondingly the fixed heat loss component was very high. These inefficient arc furnaces were replaced with one medium frequency (3000 Hz) induction furnace of capacity 125 kW, having two pots 50 kg and 100 kg respectively. The 50-kg pot is rated at 90 kW while for the 100-kg pot rating is 125 kW. Energy Saving :
Particulars Units Before implementation (Indirect arc Furnaces) 30 kg IAF 14434 13970 438 968 173208 621816 80 kg IAF 6280 2100 27 2990 75360 270542 Total / avg. 20714 16070 465 1085 248568 892359 After impleme ntation 8267 13974 330 592 99204 356142 149364 536217 1000000 1.86 2 Improve ment % Improve ment 60 -13 -29 60 -60 -60

Monthly energy consumption Metal tapped per month No of heats per month Specific energy consumption per Mt. Annual energy consumption Cost of energy Annual energy savings Annual cost savings Investment incurred Payback period

kWh Kg No kWh kWh Rs kWh Rs Rs Years

12447 -2096 -135 494 -149364 -536217

Fig . 3.5 : Energy Flow Diagram

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89

3.3.1 Analysis of Compressed Air System 3.3.1.1 Data Collection As a first step towards managing energy use in compressed air system, the following information should be collected. This exercise if done systematically can be extremely useful for identifying energy saving potential. 1) Specifications of each compressor such as capacity, pressure, motor ratings etc. 2) Loading and unloading pressure setting of each compressor 3) How many compressor normally operate and whether any shift-wise or daily variation in number of compressors operated 4) Collect data on end- use of compressed air in the plant, such as : Pressure, flow, end use, dryers, regulators, etc. 5) Pipe size and its layout 3.3.1.2 Analysis Of Equipment and System Performance The following actions need to be taken to estimate the compressed air system parameters: a) Estimation of capacity of each compressor b) Measurement of power input to the compressor at full load and part load conditions c) Estimation of total compressed air leakage in the plant and section-wise leakage estimation if possible d) Conduct a survey of compressed air leakage points by soap solution method or by using ultrasonic leakage detector. e) Estimate pressure drops in headers. f) Loading & unloading pressures and loading and unloading time of compressors . 3.3.1.3 Estimation of Capacity of Compressors The ideal method of estimating air compressor capacity is to use flow meters. In the absence of flow meters, the capacity can be estimated on site by the Pump-Up test. The compressor capacity can then be estimated by using the following formula: (P2 - P1) x Vr x Tc Pa t Where, Q= Q = Capacity of the air compressor, Nm3/min P1 = Initial pressure, (kg/cm2 a ) P2 = Final pressure, (kg/cm2 a ) Pa = Atmospheric pressure (kg/cm2 a ) Vr = Receiver volume, m3(including piping from compressor to receiver and up to receiver outlet valve and also oil separator volume for screw compressors) t = time taken to raise the pressure from P1 to P2, minutes Tc= Temperature correction factor (= Tr/Ta) Tr = Air temperature in receiver, °K (i.e. °C + 273 ) Ta = Ambient temperature, °K (i.e. °C + 273 )

The pump-up test described above gives only an estimate of the compressor capacity and cannot be considered as very accurate. It is only a simple practical method under site conditions with minimal instrumentation. A more scientific method of conducting the pump-up test with proper installed instrumentation is available in IS:5456-1985. The power consumption can be measured with portable power meter or energy meter and the specific power consumption (kW/100cfm) can be calculated. Some of the common causes of higher Specific Power Consumption are: Poor inter-cooler performance. Malfunctioning of discharge and/or suction valves. Worn out piston rings. Choked suction side filters.

Case study 11 : Installing Refrigeration dryers in Compressed Air system Brief It is recommended to replace absorption type air dryer with refrigeration type dryer as absorption dryer uses 10% - 15% purge air for re-generation of desicant . Energy Saving Saving Obtained by installing Refrigeration Dryer in Compressor
Parameter Actual load (kW) Total running hours / year
Annual Energy consumption (kWh)

Before Implementation 16.6 1800 29880 -

After Implementation 14.11 1800 25398 -

Saving / Improvement 2.49 4482 15780 94000 6

Annual savings (Rs.) Investment (Rs.) Payback period (years)

Case Study 12 : Installation of automatic drain traps in compressed air network Brief In an engineering unit, moisture traps were found stuck up in either open or closed condition thus making a loss of compressed air continuously or corroding of pipeline and other networking devices. On rectifying the faults, savings were as under: Energy Saving
Particulars Annual total energy savings, kWh Annual Cost savings, Rs. (million) Cost of implementation Rs. (million) Simple payback period (months) Actual energy savings 84,000 0.42 0.10 3

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Case Study 13 : Improving the performance of 500 cfm reciprocating compressor Brief In an engineering company, plant was having 3 nos - air compressors of IR make. All the three compressors were run continuously totaling to air requirement of 980 cfm. While the performance of 2 nos air compressors of 240 CFM each was found satisfactory, the 3rd compressor of 500 cfm was performing sub standard. The volumetric efficiency was only 87 % and the power consumption was more (20 kW/100 cfm) as against 19.4 kW/100 cfm. Efficiency of the compressor 3 had gone down. By improving the performance of this compressor, one compressor of 240 cfm was totally stopped. After maintenance the savings effected were as under: Energy Saving
Particulars Annual total energy savings, kWh Annual Cost savings, Rs. (million) Cost of implementation Rs. (million) Simple payback period (months) Actual energy savings 74,000 0.340 0.100 4

Leakage tests can be done separately for each section of the plant by isolating the supply to compressed air to the remaining sections of the plant during the leakage test. Case Study 14 : Cost of compressed air leakage from holes at different pressures
Orifice Diameter (in inches) At 3 bar (45 psig) pressure
1/64 1/32 1/16 1/8 1/4 0.211 0.845 3.38 13.5 54.1 0.0207 0.083 0.331 1.323 5.3 744 2981 11925 47628 190865

Air Leakage Scfm

Power Wasted kW

Cost of Wastage, Rs. (for 8000 hrs/year) @ Rs. 4.50/kWh

At 7 bar (100 psig) pressure 1/64
1/32 1/16 1/8 1/4

0.406
1.62 6.49 26 104

0.069
0.275 1.10 4.42 17.68

2485
9915 39719 159120 636480

3.3.1.4 Estimation Of Air Leakage Level Leakage of compressed air is a major reason for the poor overall efficiency of compressed air systems. It may be noted that, at 7 bar (100 psig), about 100 cfm air leakage is equivalent to a power loss of 17 kW i.e. about Rs. 0.62 million per annum. The leakage level can be estimated by observing the average compressor loading and unloading time, when there is no legitimate use of compressed air on the shop floor. Air Leakage in m3/min, q = Where, Q = Compressor capacity, in m3/min (as estimated from the pump-up test) T = Time on load ,min t = Time on unload, min Leakage points can be identified from audible sound. For small leakage, ultrasonic leakage detectors can be used. Soap solution can also be used to detect small leakage in accessible lines. The following points can help reduce compressed air leakage: a) b) c) d) e) f) g) Reduce the line pressure to the minimum acceptable. Selection of good quality pipe fittings. Provide welded joints in place of threaded joints. Sealing of unused branch lines or tappings. Provide ball valves (for isolation) at the main branches at accessible points. Install flow meters on major lines. Avoid installation of underground pipelines to avoid corrosion & leakage. QxT T+ t

Estimation of Pressure Drop The pressure loss from the air compressors to the end-use points may be kept at as low a level as possible, i.e., below 0.3 to 0.5 bar. The air compressors should be located close to the equipment requiring large quantum of air for reducing pressure drops. If the end-uses are spread over a large area, a ring main header can help reduce pressure drop. The pressure drop in pipelines is approximately proportional to the square of the air velocity. The pressure loss can also be calculated for straight pipe lines by the following formula Pressure drop (in bars) = 7.5 x 10 4 x Q1.85 x L d5 x p where, Q = Air flow in m3 /min. (Free air) L = Length of pipeline (m) d = Inside diameter of pipe, mm p = Initial pressure, bar (absolute) Case Study 15 : Pressure drop calculation for a 3" header and a 4" header for a flow of 100 scfm and a pressure of 7 bar, based on the above equation

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Brief Description Inlet pressure Air flow Length of pipe Pressure drop Units bar, abs scfm meter bar psi 3" Header 7 100 100 75 2.1 30.9 4" Header 7 100 100 100 0.5 7.3

3.3.2 Identifying Energy Saving Opportunities It is very important to have a systematic approach for saving energy in compressed air system. The fundamentals of this approach are basically: Manage end use of air. This includes proper understanding of end use requirement, often termed as the ultimate goal to be achieved. 2. Match the system with the end use requirement in the most efficient way. 3. Improve the efficiency of compressors and related equipments through maintenace. 4. Scouring (moisture removal) by compressed air can be replaced by high pressure blowers. The energy saving can be 80%. 5. Material conveying applications can be replaced by blower systems or preferably by a combination of belt/screw conveyers and bucket elevators. 6. For applications like blowing of components, use of compressed air amplifiers, blowers or gravity-based systems may be possible. 7. Use of compressed air for cleaning should be discouraged. 8. Replacement of pneumatically operated air cylinders by hydraulic power packs can be considered. 9. Use of compressed air for personal comfort cooling can cause grievous injuries and is extremely wasteful. If a ¼" hose pipe is kept open at a 7 bar compressed air line for personal cooling for at least 1000 hours/annum, it can cost about Rs. 1.0 lakh/annum. Operating cost of a 1.5 TR window air conditioner for the same period would be only about Rs. 12,000/- per annum. 10. Use vacuum systems in place of venturi system. 11. Mechanical stirrers, conveyers, and low-pressure air may mix materials far more economically than high-pressure compressed air. 12. Air conditioning systems can cool cabinets more economically than vortex tubes that cool by venting expensive high pressure air. Case Study 18 : Brief Installation of VSD on a compressor to avoid the compressed air blow-off in the system 1.

Pipe inside dia. mm

Normally, the velocity of compressed air should not be allowed to exceed 6 m/s. Pipe fittings like valves, elbows & no. of bends etc. also contribute to additional pressure losses. Case Study 16 : Pressure Drop (in bar) In different Pipe sizes of 100 ft. Length Brief

Nominal FAD, cfm pipe size (Free Air (in inches) Delivery) 1 2 3 4 6 10 20 50 100 200

Line Pressure, psig 40 4.39 0.54 0.43 0.41 0.24 50 3.70 0.46 0.36 0.34 0.21 75 2.68 0.33 0.26 0.25 0.19 100 2.09 0.26 0.20 0.19 0.16 125 1.72 0.21 0.17 0.16 0.14 150 1.46 0.18 0.14 0.14 0.11

Case Study 1 7 : Reduction in pressure drop in the compressed air. Brief A leading bulk drug company has three reciprocating compressors having the capacity of 280 cfm and the corresponding power consumption was 58 kW at 7.5 kg/cm2. The actual air requirement at user end was only 6.0 kg/cm2. The pressure drop in the system was taking place of the order of 1.5 kg/cm2. On analysis, it was found that high pressure drop in the system was due to under sizing of the piping. The existing(2") piping was replaced by suitable sized piping (3"). Overall saving in energy was as under: Energy Saving Particulars Annual total energy savings, kWh Annual Cost savings, Rs. (million) Cost of implementation Rs. (million) Payback period (years) Actual energy savings 35,000 0.123 0.25 2
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The chemical plant has five process fermentors, where the compressed air is used as raw material and as well as for the agitation. Five large compressors in use were of reciprocating, single stage, double acting, horizontal, non-lubricated type having the capacity of 4000 m3/hr, rated pressure 1.5 kg/cm2, rated motor 200 kW. In view of the variations in the load and the energy lost due to bleed off, variable speed drive was installed to adjust the speed based on requirement. Energy Saving
Particulars Average bleed air quantity(m /hr) Annual total energy savings, million kWh Annual Cost savings, Rs. (million) Cost of implementation Rs. (million) Payback period (months)
3

Actual energy savings 1320 0.580 1.52 2.0 16

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Case Study 19 : Brief

Energy saving in compressed air system by eliminating artificial demand

Case Study 21 : Monitoring of air consumption using hour meter installed at compressor motor and reduction of air leakages Brief In a paper and pulp industry, for supplying instrument air, two compressors working at 10 kg/cm2 and 1 m3 per minute were running. The air leakage in the system increased and the air compressors started running for more than 20 hrs a day to meet the requirement. Upon installation of the hour meters, it became easy to monitor the running hours of compressors and also estimate the air consumption as well as leakages .The leakages were arrested and also a reduction in total running hrs of compressors was achieved . Savings effected were as under: Energy Saving

In a manufacturing industry, compressed air is the major utility used in many applications. The industry has 2 centrifugal compressors of 3000 cfm each and 3 reciprocating compressors of 1000 cfm each. 1 centrifugal compressor and 2 reciprocating compressors are always running totaling to 5000 cfm. It was observed that there was a fluctuation of pressure from 98 psi to 67 psi. Two intermediate control stations each of 4500 cfm have been installed which reduced the fluctuation of pressure from 31 psi to 2 psi. Energy saving potential was as under: Energy Saving

Particulars
Particulars Actual energy savings Annual total energy savings, million kWh 0.873 Annual Cost savings, Rs. (million) 2.9 Cost of implementation Rs. (million) Payback period (months) 2.0 9

Actual energy savings 75,000 0.3 2,000 <1

Annual total energy savings, kWh Annual savings, Rs. (million) Cost of implementation Rs. Payback period (months)

Case Study No. 20 : Saving due to pressure optimization Brief In an automobile plant, it was reported that the maximum air pressure requirement at machine end is 6.5-7.0 kg/cm2 but plant is maintaining 7.0- 8.5 kg/cm2. Generating higher pressure than required is a loss of power i.e roughly 4% loss in maintaining 1 kg/cm2 higher pressure. The details of losses are as follows: Energy Saving Pressure requirement : 6.5-7.0 kg/cm2 Pressure maintained : 7.0-8.5 kg/cm2 Rated Compressor power : 75 kW for 458 cfm compressor Rated Avg. compressor power : 65 kW ( ON and OFF load) Avg. compressor power (ON and OFF load) after reduction in pressure by 1 kg / cm2 : 62.4 kW Particulars Annual total energy savings,kWh Annual Cost Savings, Rs. Cost of Implementation Payback Period Actual energy savings 10,000 61,000 Nil Immediate

Case Study 22 : Arresting of air leakages in an automobile unit Brief A leading automobile unit, which produces 2 wheelers, has seven large compressors with a rated output of 7500 cfm. Compressors consume about 60 lakh units annually (i.e about 12 % of total power consumption). The compressed air is mainly used in pneumatic tools, instruments, control valves. During the recently concluded energy audit, it was observed that the leakage in the system was 1400 cfm, which was about 20% total air consumption. After arresting the leakages, the savings to the company were as under: Energy Saving Particulars Annual total energy savings, kWh Annual Cost savings, Rs. (million) Cost of implementation Rs. (million) Payback period (month) Actual energy savings 0.864 3.0 0.2 1

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3.4

Pumps, Blowers, Fans & Variable Speed Drives

Pumping of water and blowing of air are very basic needs. This can be done by either positive displacement systems like reciprocating pumps, gear pumps, roots blowers etc. or by the centrifugal pumps and blowers. Centrifugal devices do not use a rubbing barrier as in positive displacement equipments but depend upon the kinetic energy imparted to water or air due to rotating motion. They are used in majority of applications needing FLOW due to their inherent reliability, ruggedness and reasonably good efficiency. Basic energy is proportional to the product of FLOW and TOTAL PRESSURE HEAD. The head is mainly friction head and static head. The static head is a function of choice of location and inherent system design while the friction head varies inversely with fifth power of pipe diameter and other flow passages as also to the square of FLOW. The friction based energy is thus decided by CUBE OF FLOW. The equations relating rotodynamic pump performance parameters of flow, head and power absorbed, to speed are known as the Affinity Laws and are as follows: Q N H N2 3 P N Where: Q = Flow rate H = Head P = Power absorbed N = Rotating speed Efficiency is essentially independent of speed Flow: Flow is proportional to the speed Q1 / Q2 = N1 / N2 Head: Head is proportional to the square of speed H1/H2 = (N1²) / (N2²) Power (kW): Power is proportional to the cube of speed kW1 / kW2 = (N1³) / (N2³) Optimizing the energy efficiency of a pumping system needs attention, action and investments to use the highest possible pump efficiency, to use the pump around its Best Efficiency Point (BEP) which is at a unique flow, to minimize pipe and exchanger losses, minimize/eliminate use of valves and select Minimum Needed Flow under ALL operating conditions. This may call for variable flow systems in many cases to suit operation or to SAVE energy. Changing flow will need retuning the system for optimization. Incorporating efficient pump and method of flow capacity control at the design stage or as a retrofit by using variable speed, trimming of impellers, variable pitch designs (axial flow), changing impellers and change of pumps along with minimal flow concept and better (bigger) heat exchangers, summarises the total concept of energy saving measures.
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The operation of fan is similar. There is no static head. The head in the heat exchanger is small compared to head lost in ducts, bends and dampers. In addition to the elegant universally applicable variable speed method of capacity control, we can use variable pitch designs and inlet guide vane control for fans. 3.4.1 Energy Saving in Pumps Basically, for an ideal system with given piping, the open valve system characteristics should cut the pump curve at BEP flow (Best Efficiency Point Flow). But this is rarely possible. Hence, a practical system suffers in varying degrees by : 1. 2. 3. 4. 5. Loss due to drop in efficiency of the pump for off duty point operation. Loss in throttling valve to some extent. Piping size of historical value and layout which can be changed. A pump of old design which has room for improvement. An old heat exchanger, where the design emphasis may be on lesser material content (low first cost) and smaller space giving relatively higher drop for same function. It is very important to realise that the effects of flow may be proportional to first power of Q (heat exchangers have even Q0.8), so that reduction in flow by even marginal percentage brings about considerable energy savings. An unquestioned Static Head can be altered in some cases by re-layout and other innovative changes. Very large drop (relative) in throttling valve which can be minimised or eliminated. There is a fair chance of improving new working point pump efficiency to increase savings.

6.

7. 8. 9.

The methods for saving energy by altering the pump characteristic are briefly as under : 1. 2. 3. 4. 5. 6. By trimming the impeller i.e. reduction in impeller diameter. By changing the impeller to get a different characteristic. By a change of blade angle in axial flow type if that feature exists/or installed. By changing the pump if the change is drastic/also for more efficiency. By change of Speed - Most elegant and universally applicable method. By stopping of pump, if parallel operation is properly planned.

Case Study 23 : Eliminating Throttling Losses by Use of Variable Speed Drive Brief Figure below shows a system with an unthrottled flow of 12000 lpm and a variation upto 6000 lpm. The pump efficiency figures are shown on the head-flow curve. The best efficiency of 85% is at 12000 lpm which is lowered to 69% at 6000 lpm. Static head is 10 metres. The throttled operation parameter are shown in the Table below.

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Case Study 24 : Modification of Pumps at a Fertilizer Plant : Brief An in-house energy audit by Technical Services department revealed mismatches due to insufficient data at design stage or extra safety margins. A large number of impellers were trimmed. In the Ammonia plant, 6 numbers of cooling water pumps of 960 kW motors were being operated to maintain cooling water pressure at 5 Kg/Sq. cm. Gauge. After the system study, it was decided to operate at lower head and higher flow. One heat exchanger at a height was served with a booster pump. This measure saved 500 kW. Table below summarises different saving measures resulting in a saving of 774.4 kW. Energy Saving Modification on Pumps at a Fertilizer Plant
Description Power Original Data Flow M3/hr Condensate 150 150 82.1 60.2 102 125 186 Dia Mm 321 346 258 250 280 306 350 350 Cons. kW 159 83 57 45 63 60 125 125 Head M 220 175 155.3 158 158 128 102.6 102.6 Flow M3/hr 150 150 82.1 60.2 102 125 186 186 Dia Mm 291 320 202 203 NA 294 320 320 After Modification Cons. kW 130 70.2 35 27 38 55.4 104.5 104.5 Head M 180 150 146 95 95 118 86 86 Saving kW 29 12.8 22 18 20.2 20.5 20.5 20.5

Throttling Losses and Savings By Use of Variable Speed Pump Performance With Throttling Control
Flow lpm System Pressure (m) Pump Pressure (m) Pump Efficiency (%) Pump Input (kW) Motor Load (%) F.L Motor Efficiency (%) Motor Input (kW) Starter Efficiency (%) Input (kW) 12000 23.50 23.20 86.00 53.58 97.41 90.00 59.53 99.80 59.65 9000 17.93 27.50 79.50 50.87 92.49 89.60 56.77 99.80 56.88 6000 13.35 29.50 69.00 41.92 76.20 89.00 47.10 99.80 47.20

Hot Condensate C/X - 102 Conds. C/X - 701 Conds. C/X - 101 Conds. D.M. Transfer Treated Amm. Conds.

Treated Ammonia Conds. 186

Additionally 1. 2. Ammonia CW pump was totally stopped saving 500 kW . One G.S.W. pump was stopped due to inter-connection of C.W and G.S.W, thereby saving 80 kW. Replacing the inefficient pumps with energy efficient pumps matching the characteristics with the others connected in parallel

Energy Saving The same system was equipped with an inverter with 97.5%, efficiency changing to 89.5% at reduced load (See Table below). Pump Performance With Variable Speed

Case study 25 :

Brief Flow lpm System / Pump Pressure (m) Pump Efficiecny (%) Pump Input (KW) Motor RPM Motor Load % F.L. Motor Efficiency (%) Motor Input (kW) Controller Efficiency % Input (kW) Savings Inputs (kW) % Saving (Throttled - Input) 12000 23.50 86.00 53.58 1450 97.40 93.70 57.18 97 58.95 0.70 1.12 9000 17.93 85.50 31.02 1210 56.40 93.60 33.14 94 35.25 21.63 38.03 6000 13.35 78.00 16.78 1000 30.50 90.00 18.64 89.50 20.83 26.37 55.80 In one of the Jal Board boosting stations, there were 6 nos pumps-3 of 125 HP and other 3 of 100 HP pumps. While the 125 HP pumps were giving their efficiency near to the rated efficiency of 58 %, the 100 HP pumps were giving efficiency in the range of 13% to 19 %. The efficiency had gone down as these were run in parallel with 125 HPpumps, which were having different characteristics. Further, the head generated by these pumps was much higher than required as the flow was being throttled. Energy Saving Replacement of 100 HP pump by energy efficient pump with VFD Energy saving Annual saving Investment Payback period
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: : : :

0.185 Million kWhr 0.74 Million 1.2 MIllion 20 months

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Case study No. 26 : Use of one high capacity pump in place of 4 nos of small capacity chilled water pumps Brief No. of Pumps in parallel Capacity of pumps Valve throttled New pumps (1 no.) : 4 (20 HP each) : 20.5 lps, 43.75m : 60%-80% : 50 HP

3. 4. 5. 6. 7. 8.

By Inlet guide vane - Introduces prerotation to add tangential velocity at inlet to improve entry conditions with reduced flow. Better compared to dampers. Changing to better suited blower/fan. By changing blade angle in axial flow fans if applicable. By changing the speed, which is applicable to all blowers/fans. By stopping redundant fans/blowers. Improved design FRP fans for cooling towers have given 10% to 30% savings.

Case study 27 : Replacement of Inefficient fans Brief The test results for the individual fans show that there is mismatch between fan selection and the exact requirements and the operating static pressure of these fans is between 13% and 60% of the rated pressure and the flow of fans is between 90% and 150% of the rated flow. This mismatch has resulted in low operating efficiency of the fan system. It is suggested to replace the low efficiency fans with high efficiency fans. Sl. No. 1 2 3 4 5 6 7 8 Fan Name Cooler fan A Cooler fan B Cooler fan C Air fan Reverse fan Mill fan Cement fan ESP fan % of Flow 89.78 127.36 86.74 119.32 99.65 35.03 19.41 30.99 % of Static Pressure 55.65 45.84 59.09 27.99 27.00 39.08 13.43 13.54 Static Efficiency 55.00 65.10 58.84 36 .88 16.93 18.70 4.19 9.97

Instead of 4 nos. of Pumps, one big pump of 50 HP motor and energy efficient pump was installed. Savings effected were as follows: Energy Saving Annual energy saving Annual cost saving Investment in modification Simple payback 3.4.2 : 0.123 Million kWhr : Rs 0.637 Million : Rs 0.370 Million : 7 months

System Operation and Energy Saving Methods for Blowers/Fans :

Fig. 3.6 shows a fan performance curve for flow reduction from 0.66 per unit to 0.50 per unit. The system head characteristic does not have static head in the case of blowers and fans. The system resistance consists of dampers, ducts with bends etc. and diffusers or such other equipments. The system curve follows the expression KQ2 which is a parabola starting from origin.

Energy Saving Calculation for kVA Savings by Changing the Fan Motor (OnlyCooler Fan-1 is taken for example) Parameter Power consumption (kW) Power factor Annual saving (Rs.) Fig 3.6 : Fan Performance with Variable Speed Operation All the points listed under pumps are applicable to blowers/ fans. The loss in damper at reduced flow is shown in Fig. 3.6 by shaded areas. Due to absence of static head, a larger proportion of energy is dissipated in dampers. Capacity control saving methods are listed below alongwith energy related comments: 1. 2. By outlet damper - Reduces energy use but relatively large damper loss. By inlet damper - Reduced suction reduces effective density to give reduced head/flow. Better compared to outlet damper.
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Before Implementation 108 0.80 -

After Implementation 78 0.85 -

Saving/ Improvement ( - ) 30 ( + ) 0.05 ( + ) 4,92,480

* The impeller power for the new fan is calculated by taking 10% margin in present flow. 15% margin in present static pressure and 90% fan efficiency for cooler than (for other fans - 75% fan efficiency) Total energy saving for all the fans in above table (kWh/t clinker) : 1.037 Annual saving : Rs.2.2 Million Investment : Rs.2.4 Million Payback period : 13 months

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Case Study 28: Speed Reduction of Vacuum Blowers and Agitators in Pulp & Paper Industry Brief (a) Some of the vacuum blowers of PM 1 were being operated with dampers closed to a greater degree. The blowers are belt driven. The pulley sizes are changed to reduce the speed of the fans. (b) Speed reduction was carried out on new bleached high density tower agitator. (c) The plant personnel decided to operate the blower at 2100 rpm and keep the damper fully open. After implementation, the power consumption was measured to be 17.4 kW. Energy Saving (a) Annual Saving Investment Payback period (b) Annual Saving Investment Payback period (c) Energy Saving Annual energy saving Annual saving Investment Payback period : Rs. 0.12 Million : Rs. 0.1 Million : 10 months : Rs.93000 : Rs.15000 : 2 months : : : : : 16 kWh 96000 kWh Rs. 0.48 Million Nil Immediate

Energy saving Average running kW of ID fan with VFC Average running kW of ID fan with VFD Energy saved/day (42 x 24 hours) Annual saving Investment Payback period : : : : : : 55 kW 13 kW 1008 kWh Rs. 0.647 Million Rs. 1.2 Million 2 years

Case Study 31: Installation of Variable Frequency Drive for Control of ID Fans in place of Inlet Damper Control in Pulp & Paper Industry Brief 50 tph AFBC boiler was provided with 2 nos. ID fans. The furnace draft was being controlled by varying the inlet damper position of ID fans. Each ID fan is driven by 90 kW motor, 750 rpm. The normal damper opening when boiler was at full load awas 55%. It was decided to install 2 nos. 90 kW VFDs for fan control. Energy Saving Power consumption before VFD Power consumption after VFD Annual Saving Investment Payback period Case Study No. 32 : VFD in Pump in Paper Plant Brief Industry Application Motor Rating : : : Paper Pump (Water Suction) 3 Phase AC Induction Motor Rating : 130 HP - Volt : 415 V Current : 160 A - RPM : 1440 Motor was run through Star-Delta Starter 1. Excess Water drained & hence wastage of water 2. Energy loss due to drain control 3. Mechanical wear & tear Water outlet controlled by varying the speed of AC motor using V.F.D. : : : : : 84 kW (each motor) 58 kW (each motor) Rs. 0.75 Million Rs. 1.1 Million 18 months

Case study 29 : Interconnection of Blowers in the plant Brief There are 7 nos. of 3000 cfm (6" head) blower for machine exhaust. It is suggested to inter-connect the blower with damper so that minimum number of blowers can be run common to all machines and can also be run independently if required. Energy Saving Annual saving Investment Payback period : Rs. 1,62,940 : Rs. 25000 : 2 months

Previous System Problem Observed

: :

Present System

:

Case Study 30 : Replacement of Variable Speed Fluid Coupling (VFC) with Variable Frequency Drive (VFD) in Pulp & Paper industry Brief The variable fluid coupling was replaced with a variable frequency drive for I.D. fan of soda recovery boiler, for furnace draft control. The fan was operating around 740 rpm, whereas motor speed was 970 rpm. Recognizing the efficieny difference between VFC and VFD, VFD was installed to replace VFC.

Previous System Present System

Freq (Hz) 50 25 to 40

Amp. 100 40 to 50

kW 60 40

Water m3 / hr. 130 130

Drain Valve 50 to 70 open 100% (Average)

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Energy Saving Actual capacity of 100 kW motor Actual requirement for process Without drive power consumption With AC Drive power consumption Energy Saving Annual Saving Investment Payback period 3.4.3 Sample Calculations A) An industrial fan with measured flow rate of 90 m3/s has 80 mm WC static pressure developed across it. The motor power drawn is 120 kW and motor efficiency of 86%. We first find out the fan static efficiency. For the above fan, the bagfilter in the system was replaced with ESP (Electrostatic Precipitator). The pressure drop across the bagfilter was 65 mm WC. With ESP, pressure drop was 20 mmWC. Flow rate increased by 20%. The original flow can be obtained by two options: a) Impeller trimming : : : : : : : : 500 m3/hr 130 m3/hr 60 kW 40 kW 480 kWh/day Rs 0.65 Million Rs 0.325 Million 5 months

Option (a) = 90 x 1.2 = 108 m3/hr Pressure developed across fan, H2 = 80-(65-20) = 35 mm WC New fan static efficiency = 68 -5 = 63% For flow Q1 = 90 m3/s, H1 =?, Q2 = 108 m3/s and H2= 35 mm WC (Q2/ Q1)2 = (H2/H1) (108/90)2 = (35/H1) H1 = (90/108)2 x35 = 24 mm ) Power developed at fan shaft = 90 x 24 102 x 0.63 = 33.61 kW New impeller diameter (D2) Considering the fan law (D1 / D2) = (Q1/Q2) = (N1/N2) D1 = 70 mm, Q1=108, Q2 = 90, D2 = 58 mm, N1= 850 RPM New impeller diameter, D2 = 58 mm New RPM = 90/108 x 850 = 708 RPM Option (b) Efficiency at reduced RPM Power developed at fan shaft Differential power savings = 66% = 90 x 24 102 x 0.66 = 32.08 kW = 1.53 / 0.86 x 8760 hours/annum x Rs.4 / kWh = Rs. 62340 New Flow rate, Q2

b) Reduced RPM with pulley diameter change For option (a), if original impeller size were 70 mm in diameter, what would be the new impeller diameter if efficiency drops by 5%? For option (b), what would be the required reduction in RPM if fan was originally running at 850 RPM and efficiency at reduced RPM is expected to be 66%? We finally find out the differential energy savings between the two options at 8760 hours/annum and at Rs.4 / unit. = 120 kW = 120 x 0.86 = 103.2 kW Flow, Q1 = 90 m3/s Pressure developed across fan, H1 = 80 mm Original impeller diameter (D1) = 70 mm Original RPM = 850 RPM Fan static efficiency = Flow x Pressure developed across fan x100 102 x Power developed at fan shaft = 90 x 80 x 100 102 x 103.2 = 68 % Motor power drawn Power input at fan shaft (BHP)

B) A centrifugal pump pumping water operates at 35 m3/hr and at 1440 RPM. The pump operating efficiency is 68% and motor efficiency is 90%. The discharge pressure gauge shows 4.4 kg/cm2. The suction is 2m below the pump centerline. If the speed of the pump is reduced by 50 % estimate the new flow, head and power Flow = 35 m3/hr Head developed by the pump = 44 - (-2) = 46 m Hydraulic Power = Q (m3/s) x Total head, hd - hs (m) x (kg/m3) x g (m2/s)/1000 Power drawn by the motor = (35/3600) x 46 x 1000 x 9.81 1000 x 0.68 x 0.9 (i.e. efficiency of pump & motor) = 7.2 kW Flow at 50 % speed Q2 : 35 / Q2 = 1440/720 Q2 = 17.5 m3/hr Head at 50 % speed H2 : 46 / H2 = (1440/720)2 H2 = 11.5 m Power at 50 % speed P2 : 7.2/kW2 = 14403 / 7203 P2 = 0.9 kW

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3.5 Refrigeration & Air Conditioning System Refrigeration systems are used for process cooling by chilled water or brine, ice plants, cold storage, freeze drying, air-conditioning systems etc. The refrigerant temperatures for process cooling applications may range from 15°C to as low as 70°C. Comfort air-conditioning requires refrigerant temperatures in the range of 0°C to 5°C. Air-conditioning generally implies cooling of room air to about 24°C and relative humidity of 50%-55%. In some applications, air-conditioning involves humidification of air up to 70%80% relative humidity (as in textile industry) or dehumidification of air to less than 20% (e.g.in some pharmaceutical industries, rooms housing sophisticated electronic equipment, storage rooms for hygroscopic materials etc.). There are types of refrigeration system : a) Vapour Compression System b) Vapour Absorption System Vapour compression machines are used extensively for refrigeration. This system requires motive power to drive a compressor, which is supplied by an electric motor or engine. With increasing electricity prices, there is renewed interest in Absorption Refrigeration machines, wherein heat is used for cooling. Users having waste heat or economical heat energy sources are using the absorption chillers. 3.5.1 Energy Consumption in Refrigeration Systems The cooling effect of refrigeration systems is generally quantified in tonnes of refrigeration. 1 Tonne of Refrigeration (TR) = 3023 kcal/hr = 3.51 kWthermal = 12000 Btu/hr

The other commonly used and easily understood figure of merit is Specific Power Consumption = Power Consumption (kW) Refrigeration effect (TR) A lower value of Specific Power Consumption implies that the system has better efficiency. 3.5.1.1 Specific Energy Consumption in Refrigeration andAir-conditioning Systems Table 3.9 shows the figures of merit for Vapour Compression systems using reciprocating and centrifugal compressors. Table 3.10 shows the figures of merit for steam heated and also direct natural gas / LDO fired absorption chillers; here, in addition to COP and EER, the specific steam consumption in kg/hr/TR is mentioned. Table 3.9 : COP, EER & Specific Power for Vapour Compression Systems (for chilled water at 8oC with water cooled condensers)
Capacity TR 10.78 32.20 48.30 64.40 9.26 13.90 42.00 563.67 1.5 Power kW 6.62 21.38 32.06 42.75 7.00 12.10 34.50 329.94 1.8 to 2.3 COP 5.75 5.32 5.32 5.32 4.62 4.03 4.28 6.00 2.9 to 2.3 EER Btu/hr/W Specific Power kW/TR 19.7 18.2 18.2 18.2 15.8 13.8 14.6 20.5 7.8 to 10 0.61 0.66 0.66 0.66 0.76 0.87 0.82 0.59 1.2 to 1.5

Open Type Reciprocating Compressors

Semi-hermetic Reciprocating Compressors

Open Type Centrifugal Compressors Window Air-conditioners & Split Units

Note : The above data is based only on the compressor power consumption, auxiliary power for pumps, fans etc. is excluded. Table 3.10 : COP, EER & Specific Power for Vapour absorption Systems (for chilled water at 8oC with water cooled condensers)

The commonly used figures of merit for comparison of refrigeration systems are Coefficient of Performance (COP), Energy Efficiency Ratio (EER) and Specific Power Consumption (kW/TR). The definition of these terms are given below. If both refrigeration effect and the work done by the compressor (or the input power) are taken in the same units (TR or kcal/hr or kW or Btu/hr), the ratio is COP = Refrigeration Effect Work done If the refrigeration effect is quantified in Btu/hr and the work done is in Watts, the ratio is EER = Refrigeration Effect (Btu/hr) Work done (Watts)

Capacity TR

Steam pressure Steam cons. kg/cm2 K=Kg/hr.

COP

EER Btu/hr/W

Specific steam cons. Kg/hr/TR 8.75 4.90 4.75 4.76 4.59 0.35 m3/hr/TR 0.36 lit/hr/TR

Higher COP or EER indicates better efficiency.

Single Effect Chiller (Steam heated) 3.0 2101.0 240 Double Effect Chiller (Steam heated) 100 8.0 490.2 155 8.0 736.5 270 8.5 1284.0 500 8.0 2296.0 Double Effect Chiller (Direct fired) 3 78 27.3 m /hr natural gas 150 54.6 lit/hr LDO
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0.61 1.10 1.13 1.13 1.17 0.96 0.96

2.10 3.76 3.86 3.86 4.00 3.28 3.27

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Comments : a) Well designed and well maintained vapour compression systems, using reciprocating compressors, for chilled water at about 8°C have COP of 4 to 5.8, EER in the range of 14 to 20 Btu/hr/W and Specific Power Consumption in the range of 0.61 to 0.87 kW/TR. It may be noted that Open-type compressors are more efficient than semi-hermetic compressors.

(b)

Operate at Higher Temperature

The approximate thumb rule is that for every 1oC higher temperature in the evaporator, the specific power consumption will decrease by about 2% to 3%. (c ) Accurate Measurement and Control of Temperature

b) Centrifugal compressors, which are generally used for cooling loads about 150 TR, can have COP of about 6, EER greater than 20 and Specific Power Consumption of 0.59 kW/TR. c) Double Effect Absorption chillers at about 8°C have COP in the range of 1 to 1.2, EER in the range of 3.3 to 4 Btu/hr/W. The Specific Steam Consumption of double effect machines is in the range of 4.5 to 5.25 kg/hr/TR, at a steam pressure of 8 to 8.5 bar. The specific fuel consumption figures of directly fired double effect chillers are 0.35m3/hr/TR (natural gas) and 0.36 lit/hr/TR (LDO). In comparison with compression system, it can still save energy cost if waste heat or any other cheaper alternative fuel is available.

When the refrigeration system's cooling capacity is significantly more than the actual cooling load, expansion valve control based on superheat sensing often leads to supercooling, resulting in an energy penalty due to unnecessarily lower temperature and also lower COP at lower temperatures. (d) Reduce Air-conditioning Volume and Shift Unnecessary Heat Loads • • • • (e) • • • • • • • • • • (f) Unnecessary heat loads may be kept outside air-conditioned spaces. Use False Ceilings Use Small "Power Panel" Coolers Use Pre-Fabricated, Modular Cold Storage Units Minimise Heat Ingress Check and Maintain Thermal Insulation Insulate Pipe Fittings & Flanges Use Landscaping to the Reduce Solar Heat Load Reduce Excessive Window Area Use Low Emissivity (Sun Control) Films Use Low Conductivity Window Frames Provide Insulation on Sun-Facing Roofs and Walls. Provide Evaporative Roof Cooling Use Doors, Air-Curtains, PVC Strip Curtains Use High Speed Doors for Cold Storage Using Favourable Ambient Conditions • • • Use Cooling Tower Water Directly for Cooling in Winter Design New Air-conditioning Systems with Facility for 100% fresh air during winter Use Ground Source Heat Pumps

The system efficiency of both vapour compression and absorption systems is critically dependent on the performance of the heat exchangers i.e. evaporator, condenser and cooling tower. Any deterioration in these equipment leads to huge energy penalties. 3.5.2 Energy Saving Opportunities (a) • • Avoid Refrigeration & Air-conditioning to the Extent Possible Use Evaporative Cooling for Comfort Cooling in Dry Areas : Use Cooling Tower Water at Higher Flows for Process Cooling :

Table 3.11 : Effect of Evaporator and Condenser Temperatures on Refrigeration Machine Performance Evaporator Temperature o C +5 Capacity +35 151 94 0.62 129 90 0.70 103 84.2 0.82 Condens er Temperature o C +40 143 102.7 0.72 118 96.8 0.82 96 89.6 0.93 +45 135 110.6 0.82 111 103 0.93 90 94.7 1.05 +50 127 117.8 0.93 104 108.9 1.05 84 99.4 1.19

(g) Use Evaporators and Condensers with Higher Heat Transfer Efficacy • Use Heat Exchangers with Larger Surface Area 1°C higher temperature in the evaporator or 1°C lower temperature in the condenser can reduce the specific power consumption by 2 to 3%. Use Plate Heat Exchangers for Process and Refrigeration Machine Condenser Cooling Plate heat exchangers have a temperature approach of 1oC to 5oC instead of around 5oC to 10oC for shell and tube heat exchangers. Avoid the Use of Air Cooled Condensers for large cooling loads . Use evaporative Pre-coolers for Air-cooled Condensers

Capacity (TR) Power cons. (kW) Sp.Power (kW/TR) Capacity (TR) Power cons. (kW) Sp.Power (kW/TR) Capacity (TR) Power cons. (kW) Sp.Power (kW/TR)

0

•

-5

• •

110

111

Case Study 33 : Replacement of Existing Evaporator with a New Evaporator with Better Heat Transfer Efficacy Brief

The methods used for air purging are : • • Direct venting of the air-refrigerant mixture, which is a primitive manual technique. A small compressor draws a sample of the refrigerant gas and compresses the mixture, condensing as much as possible of the refrigerant, and vents the vapour mixture that is now rich in non-condensibles. A low temperature evaporator, in-built in the system, condenses most of the refrigerant from the refrigerant-air mixture drawn from the condensor or receive and vents the non-condensibles. This method does not require a separate compressor and is used widely.

After achieving the saving by reduction in speed of compressors, a decision was taken to replace the existing "Ammonia Evaporator Coil in Tank" with "Shell & Tube Heat Exchanger". The comparative measurements are as follows. Parameter Power consumption (kW) Operating hrs./day Energy Consumption (kWh/day) Energy Saving Annual savings Annual savings Investment Payback period : : : : 18371 kWh Rs. 82670 Rs. 0.12 Million 1.5 years Before Implmentation 39.9 10 323 After Implementation 32.3 6.7 267 Saving / Improvement 7.6 3.3 56

•

Purging of non-condensibles plays an important role in maintaining the efficiency of refrigeration machines. Case Study 34 : Modification in Chilled Water Pumping System Brief The chilled water system had primary (chiller side) and secondary (process side) pumps with a hot well and cold well arrangement. Since the chilled water requirement for the plant was reasonably steady, it was decided to eliminate the primary pump and connect the warm chilled water from the secondary side directly to the chiller, bypassing the hot well. In view of the increased pressure requirement, a new, efficient pump of appropriate head requirement was recommended. The power consumption scenario before and after this change is as follows: Energy Saving Parameter Operating hrs. of primary pump (hrs.) Energy consumption (kWh/day) Operating hrs. of secondary pump (hrs.) Energy consumption (kWh/day) Total power consumption (kWh/day) Before Implementation 10 85 24 271 356 After Implementation NIL NIL 24 139 139 Saving / Improvement 132 217

3.5.2.1 Energy Saving Opportunities in Normal Operation • • • • • • • • • Use Building Thermal Inertia Put HVAC Window Air Conditioners and Split Units on Timer or Occupancy Sensing Control Interlock Fan Coil Units in Hotels with Door Lock or Master Switch Improve Utilisation Of Outside Air. Maintain Correct Anti-freeze Concentration Install a Control System to Co-ordinate Multiple Chillers. Permit Lower Condenser Pressures during Favourable Ambient Conditions. Optimise Water/Brine/Air Flow Rates Defrosting : The most widely used methods for defrosting are: 1. Shutting down the compressor, keeping the fan running and allowing the space heat to melt the frost. 2. Using out side warm air to melt the frost after isolating the coil from the cold room. 3. Using electric resistance heaters in thermal contact with the coil. 4. Bypass the condenser and let the hot gas into the evaporator to melt the frost. 5. Spray water on the coils to melt the frost. Match the Refrigeration System Capacity to the Actual Requirement Monitor Performance of Refrigeration Machines

Case study 35 : Replacement of inefficient condensers of central AC plant of administrative building of a corporate house Brief In the administrative building, there are two compressors installed by a company. Each compressor is of 60 TR rating as per normal perception of the operating staff. Originally there were two 10 HP pumps for circulation of condenser cooling water and the cooling was achieved by spray nozzles. Subsequently an induced draft cooling tower was installed for condenser water cooling. Further one 15 HP pump was put in parallel to existing 10 HP pumps because of poor cooling and high discharge problem, it was thought that the water supply was inadequate. There are two independent DX coils (Air Handling Units).
113

• •

3.5.2.2 Maintenance to Ensure Energy Efficient Operation • • • • Clean Fouled Heat Exchangers Specify Appropriate Fouling Factors for Condensers Do Not Overcharge Oil Purging the Condenser of Air

112

During the study the pressures, temperatures & water flow in the cooling water circuit were measured. It was observed that there was a high discharge pressure and low suction pressure due to heavy scaling in condenser. Consequent upon study, the condensers were replaced. Valves were replaced with butterfly valves and cooling coils were cleaned. Filters of AHU units were also replaced. Energy Saving Annual energy saving Annual Saving Investment Payback period : : : : 21275 kWh Rs. 75,000 Rs. 0.16 Million 2 years

-

-

Case study 36 : Savings due to stopping bypass through idle pumps and idle condensers. Brief In an automobile plant, condenser water was flowing through the idle pumps and the idle condensers resulting in loss of head as the valves had broken down and were passing. By stopping by-pass though idle pumps and idle condensers the energy savings was as follows : Energy Saving Annual Energy Saving Annual Saving Investment Payback 3.5.3 Cooling Towers : : : : 2760 kVAh Rs.979800 Nil Immediate

Periodically clean plugged cooling tower distribution nozzles. Install new nozzles to obtain a more uniform water pattern. Replace splash bars with self-extinguishing PVC cellular film fill. On old counterflow cooling towers, replace old spray type nozzles with new square spray ABS practically non-clogging nozzles. Replace slat type drift eliminators with low pressure drop, self extinguishing, PVC cellular units. Follow manufacturer's recommended clearances around cooling towers and relocate or modify structures that interfere with the air intake or exhaust. Optimize cooling tower fan blade angle on a seasonal and/or load basis. Correct excessive and/or uneven fan blade tip clearance and poor fan balance. Use a velocity pressure recovery fan ring. Consider on-line water treatment. Restrict flows through large loads to design values. Shut off loads that are not in service. Take blow down water from return water header. Optimise blowdown flow rate. Send blowdown water to other uses or to the cheapest sewer to reduce effluent treatment load. Install interlocks to prevent fan operation when there is no water flow. Replace ordinary Aluminium fans by more energy efficient aerodynamically designed FRP fans (Fibre Reinforced Plastic).

Case study 37 : Replacement of existing metal (aluminum alloy) blades by FRP blades for cooling towers. Brief The cooling tower specification is given below: Sl. No. 1. Location Cooling Plant Cooling tower Specification Capacity 200 TR Fan M otor Rated Power (kW) 11.5 Actual Power kW 5.93

In many plants, after the cooling tower has been in service for a few years, the need for improving its performance is felt. This may be due to: a) Deterioration of efficiency of the cooling tower, b) Deterioration in the efficiency of the heat exchangers (coolers, condensers etc.) at the end-use side, c) Additional heat rejection due addition of equipment, plant capacity etc. Two parameters, which are useful for determining the performance of cooling towers, are the Temperature Range and Temperature Approach. 3.5.3.1 General Tips to Save Energy in Cooling Towers Control cooling tower fans based on leaving water temperatures. Control the optimum temperature as determined from cooling tower and chiller performance data. Use two-speed or variable speed drives for cooling tower fan control if the fans are few. Stage the cooling tower fans with on-off control if there are many. Turn off unnecessary cooling tower fans when loads are reduced. Cover hot water basins to minimize algae growth that contributes to fouling. Balance flow to cooling tower hot water basins.
114

Replace the aluminum blades by new energy efficient FRP blades. By using FRP blades there will be a minimum saving of 10% in the energy. Savings obtained by conversion of aluminium blades to FRP blades. Energy Saving Actual power on cooling tower fan motor : 5.93 kW Percentage of power savings by conversion to FRP blades : 10% Working hrs/ day : 24 Working days/ year : 355 Tariff (Rs./unit) : Rs. 3.53 Annual saving : 5.93 x 0.10 x 24 x 355 = 5,052,36 kWh Annual saving @ of Rs 3.53/kWh : Rs.17,834 Investment : Rs.10,000 Payback period : 7 months

-

115

Case study 38 : Installation of automatic temperature controller in the cooling tower systems. Brief Install automatic temperature controller for cooling towers (28-30 C). The controller switches off the fan when the cold well temperature goes below the set temperature and switches on when temperature goes above the set temperature (2830 0C). Energy Saving
Parameter Annual Power Consupmtion (kWh) Before Implementation 114423 After Implementation 80096 Saving/ Improvement % 30%
0

3.6.2 Transformer Operation 3.6.2.1 Variation of losses during operation The losses vary during the operation of a transformer due to loading, voltage changes, harmonics and operating temperature. Case Study 39: Parallel operation of transformers in a Tea Industry Brief Energy Audit for Tea Factories making C.T.C. Tea, was conducted. Power is received at 22 kV and 11 kV by separate lines. This is stepped down by two 500 kVA Transfromer 22 kV/433V which feeds segregated loads. The typical loss figures for 500 kVA transformers are 1660 W for no load and 6900W as load losses for 100% load. It was recommended to parallel both transformers for a total 500 kVA load on secondary side. Also, cut off one transformer from H.V. side in lean season and holidays when the load is 5% to below 25%. Calculations For total load of 500 kVA, there are three options. a) Only one transformer takes full 500 kVA Load. Losses = 1 . 66 ( No L oad) + ( 500 /500 ) 2 x 6 . 9 k W ( l oad l osses )=8.56 kW b)One transformer takes segregated 300 kVA while second takes 200 kVA segregated load. Losses = 1 . 66 + ( 300 /500 )2 x 6 . 9 + 1 . 66 + ( 200 /500 ) 2 x 6 . 9 k W=6.90 kW c) Both are paralleled to take 250 kVA each. Losses = 2 (1.66 + (250/500)2 x 6.9) kW= 6 .77 kW. Thus on major load, the losses are minimum by paralleling both transformers. Operation at part load during lean season : a) Two paralleled transformers Losses = 2 { 1 . 66 + ( 0 . 25 /2 ) 2 x 6 . 9 } = 3 . 54 k W at 25 % load Losses = 2 { ( 1 . 66 ) + ( 0 . 05 /2 ) 2 x 6 . 9 } = 3 . 33 k W at 5 % load b) Only one transformer is energized Losses = 1 . 66 x ( 0 . 25 ) 2 x 6 . 9 = 2 . 09 k W at 25 % load Losses = 1 . 66 x ( 0 . 05 ) 2 x 6 . 9 = 1 . 68 k W at 5 % load Thus losses are minimum at low loads using only one transformer . The tariff was kVA of M. D. x R s . 60 + R s . 0 . 89 x k Wh + R s . 150 meter rent. The total annual consumption for the factory was 1.85 Million kWh per year and the electricity bill was Rs 2.04 Million giving Rs 1.10/kWh as average cost.

Annual Saving Investment Payback period 3.6 Energy Savings in Transformers

: Rs.137300 : Rs.50000 : 5 months

Transformer is the most efficient equipment in an electrical system. Distribution transformers are very efficient, with efficiencies of 97% or above. It is estimated that transformer losses in power distribution networks can exceed 3% of the total electrical power generated. In India, for an annual electricity consumption of about 500 billion kWh, this would come to around 15 billion kWh. 3.6.1 Losses in Transformers

Transformer losses consist of two parts: No-load loss and Load loss 1. No-load loss (also called core/iron loss) is the power consumed to sustain the magnetic field in the transformer's steel core. Core loss occurs whenever the transformer is energized; core loss does not vary with load. Core losses are caused by two factors: hysteresis and eddy current losses. Hysteresis loss is that energy lost by reversing the magnetic field in the core as the magnetizing AC rises and falls and reverses direction. Eddy current loss is a result of induced currents circulating in the core. 2. Load loss (also called copper loss) is associated with full-load current flow in the transformer windings. Copper loss is power lost in the primary and secondary windings of a transformer due to the ohmic resistance of the windings. Copper loss varies with the square of the load current. (P = I²R) For a given transformer, the manufacturer can supply values for no-load loss, PNOLOAD, and load loss, PLOAD. The total transformer loss, PTOTAL, At any load level can then be calculated from: PTOTAL = PNO-LOAD + (%Load/100)² x PLOAD Where transformer loading is known, the actual transformers loss at given load can be computed as:
2

kVA Load = No load loss + Rated kVA x (full load loss)

116

117

Energy saving Annual energy saving Annual saving Investment Payback period : 1000 kWh : Rs.10000 : Nil : Immediate

Saving in load losses = (Per unit loading as per kW) 2 x Load losses at full load x 1 [( pf ) - 1]
2

Thus, if p.f. is 0.8 and it is improved to unity, the saving will be 56.25% . Case study 40 : Reallocation of the load of transformer Brief Presently there are 3 numbers of transformers in a plant. From the data given it can be seen that Transformer No.3 i.e. 1250 kVA transformer is loaded only 28.70% i.e. 359 kVA against 1250 kVA. It is recommended to shift the load to a lower capacity transformer of 750 kVA which is lying idle. Transformer Loading:
Transformer 1 2 3 4 Rated kVA 2000 2000 1250 750 Voltage 440 440 440 440 Current 1200 1280 471 Loading kVA 914.94 953.29 358.87 Loading % 45.72 47.66 28.70 Idle

3.6.2.2 Energy Saving by optimum -utilisation of transformers Table 3.12 summarises the variation in losses and efficiency for a 1000 kVA transformer and also shows the difference in losses by using a 1600 kVA transformer for the same. The 1000 kVA transformer has a no load loss of 1700 watts and load loss of 10500 Watts at 100% load. The corresponding figures for 1600 kVA transformer are 2600 Watts and 17000 Watts respectively. Loading is by linear loads. Temparatures assumed equal. Table 3.12 : Comparison of transformer losses
TRANSFORMER-1 1000 kVA, No load losses = 1700 W Per unit Load 0.1 0.2 0.4 0.6 0.8 1.0 Load losses 105 420 1680 3780 6720 10500 Total losses 1805 2120 3380 5480 8420 12200 Output kW 100 200 400 600 800 1000 Efficiency % 98.23 98.9 5 99.16 99.09 98.96 98.18 TRANSFORMER-2 1600 kVA. No load losses = 2600 W Load losses, W 60 265 1062 2390 4250 6640 Total losses, W 2660 2865 3662 4990 6850 9240 861 745 282 -490 -1570 -2960 Difference in losses, W

Savings obtained by reallocating transformer No.3 load to idle transformer: Calculations Existing average load Existing transformer No.3 rating Percentage loading of TR : 3 Recommended Transformer rating with respect to average load Copper loss for existing 1250 kVA transformer = 358.87 kVA = 1250 kVA = 28.70% = 750 kVA

= (0.2870)2 x 6 x 24 x 330 = 3914 kWh = 0.59 kW (where 6 kW = full load copper loss of existing 1250 kVA transformer-considering 330 days 24 hrs operation in a year) Iron loss for 1250 kVA transformer = 2.5 x 24 x 365 = 21900 kW (Where 2.5 kW = iron loss for1250 kVA transformer) Total loss for 1250 kVA transformer = 21900 + 3914 kWh = 25814 kWh

The efficiency of 1000 kVA transformer is maximum at about 40% load. Using a 1600 kVA transformer causes under loading for 1000 kW load. The last column show the extra power loss due to oversized transformer. As expected, at light loads, there is extra loss due to dominance of no load losses. Beyond 50% load, there is saving which is 2.96 kW at 1000 kW load. The saving by using a 1600 kVA transformer in place of a 1000 kVA transformer at 1000 kW load for 8760 hours/annum is 25930 kWh/year @ Rs .5.0/kWh, this is worth Rs 0.129 Million. The extra first cost would be around Rs 1.5 Million. Hence deliberate oversizing is not economically viable. 3.6.2.3 Reduction of losses due to improvement of power factor Transformer load losses vary as square of current. Industrial power factor vary from 0.6 to 0.8. Thus the loads tend to draw 60% to 25% excess current due to poor power factor. For the same kW load, current drawn is proporational to kW/pf. If p.f. is improved to unity at load end or transformer secondary, the saving in load losses is as under.
118

On replacement of 1250 kVA transformer with 750 kVA transformer, the average loading of 750 kVA transformer will be = 359 = 47.85% 750 Copper loss for 750 kVA transformer =(0.4785)2 x 4 x 330 x 24 = 7255 kWh (where 4 kW = full load copper loss of 750 kVA transformer-considering operating hours – 24 for 330 days) = 1.95 x 365 x 24 = 17082 kWh (where 1.95 kW = iron loss for 750 kVA transformer) Total losses for 750 kVA transformer
119

Iron loss for 750 kVA transformer

= 7255 + 17082 = 24337 kWh

Energy Saving Savings in kWh Annual Savings @ Rs.4.20 per kWh Case study 41: Brief Power is received from the electricity board and 3 nos. of 10000 kVA, 33kV/ 433 volts transformer are installed for stepping it down to 433 volts for plants distribution. Each transformer feeds its own P.C.C. and facility is available to run the transformer in parallel. Now the transformers are run independently and the loads in them are not balanced. The load on the T.R. 2 and 3, which were in service, was monitored for 24 hrs. These transformers have their maximum efficiency at 25 to 50% of loading. As per monitoring, transformer 3 is loaded around 50% and transformer 2 is loaded at less than 25% of their respective rated capacities both operating outside their maximum efficiency ranges. These transformers were run in parallel. Energy Saving Total losses before parallel operation Total losses after parallel operation Energy saving by parallel operation Monetary saving/yr. Operation Load on each transformer in day time Load on each transformer in night time Investment Payback period : : : : : : : : : 75.2 kW 64.5 kW 4035 kWh Rs.14,204 24. x 365 hrs 66% - 77% 15% - 20% Nil Immediate = 25814 – 24337 = 1477 kWh =1477 x 4.20 = Rs. 6203

Monetary saving Investement Payback period 3.7 Energy Savings in Lighting

: Rs.52,000 : Nil : Immediate

Operating the two transformers in parallel to reduce transformer losses.

Lighting energy consumption contributes to 20 to 45% in commercial buildings and about 3 to 10% in industrial plants. Most industrial and commercial energy users are aware of energy savings in lighting systems. Significant energy savings can be realized with a minimal investment of capital and common sense. Table 3.13 : Recommended lighting levels

Illuminance Examples of Area of Activity level (lux)
General Lighting for rooms and areas used either infrequently and/or casual or simple visual tasks 20 50 70 100 150 General lighting for interiors 200 300 Minimum service illuminance in exterior circulating areas, outdoor stores , stockyards Exterior walkWays & platforms. Boiler house. Transformer yards, furnace rooms etc. Circulation areas in industry, stores and stock rooms. Minimum service illuminance on the task. Medium bench & machine work, general process in chemical and food industries, casual reading and filing activities. Hangers, inspection, drawing offices, fine bench and machine assembly, colour work, critical drawing tasks. Very fine bench and machine work, instrument & small precision mechanism assembly; electronic components, gauging & inspection of small intricate parts (may be partly provided by local task lighting) Minutely detailed and precise work, e.g. Very small parts of instruments, watch making, engraving.

450

1500

Case study 42 : Power saving by optimizing transformer operation in large Government building Brief One transformer is dedicated to one separate annexe building, the other 4 nos are connected in the configuration of 2 each on east and west wing of the buildings. Switching off one transformer each on west and east wing load during weekly off days and transferring the load on the other transformers in line shall save the the no-load losses of the transformer & the maximum efficiceny of the other 2 transformers can be attained by loading at 40-50 % load. Energy Saving Energy Saving per hour Total energy saving : 2kW : 13,000 kWh
120

Additional localised lighting for visually exacting tasks

3000

(Source : CIE, IES) Indian standards IS 3646 & SP-32 describes the illuminance requirements at various work environments in detail. 3.7.1 Energy Saving Opportunities 3.7.1.1 Use Natural Day Lighting The utility of using natural day lighting instead of electric lighting during the day is well known, but is being increasingly ignored especially in modern air121

conditioned office spaces and commercial establishments like hotels, shopping plazas etc. Industrial plants generally use daylight in some fashion, but improperly designed day lighting systems can result in complaints from personnel or supplementary use of electric lights during daytime. Light pipe: This is a reflective tube that brings clean light from the sky into a room, no need for lighting or incandescent bulbs. These are aluminium tubes having silver lining inside. One 13" light pipe can illuminate about 250 sq.ft of floor area with an illuminance of 200 lux. A 9" dia pipe can give the same iilluminance over a 100 sq.ft area. A 4 ft length of light pipe of the above size provides a daytime average of 750 watts worth of light in June, 250 watts in December. If the pipe length increases to 20 ft, 50% of the light reaches the surface. These are expensive, costing between 150 to 250 dollars and is one of the emerging technologies in day lighting. Case study 43 : Installation of solar energy systems in canteen/guest houses Brief Solar water heaters in canteen were installed in place of electric heaters. By installing these heaters, at least 8 months in an year, solar energy could be used. Existing heaters were retained for supplementing these units in case of bad weather or rainy season. Energy Saving Annual saving Annual saving Investment Payback period : 0.216 Million kWh : Rs. 0.68 Million : Rs. 0.45 Million : 8 months

Table 3.14 :Information on Commonly Used Lamps
Lamp Type Lamp Rating in Watts (Total Power including ballast losses in Watts) Efficacy (including ballast losses, where applicable) Lumens/Watt 8 to 17 Color Lamp Rendering Life(hrs) Index

General Lighting Service 15,25,40,60,75,100,150,200, (GLS) (Incandescent bulbs) 300,500 (no ballast) Tungsten Halogen (Single ended) Tungsten Halogen (Double ended) Fluorescent Tube lights (Argon filled) Fluorescent Tube lights (Kryptonne filled) Compact Fluorescent Lamps (CFLs) (without prismatic envelope) Compact Fluorescent Lamps (CFLs) (with prismatic envelope) Mercury Blended Lamps 75,100,150,500,1000,2000 (no ballast) 200,300,500,750,1000,1500, 2000 (no ballast) 20,40,65 (32,51,79) 18,36,58 (29,46,70) 5, 7, 9,11,18,24,36 (8,12,13,15,28,32,45)

100

1000

13 to 25 16 to 23

100 100

2000 2000

31 to 58

67 to 77

5000

38 to 64 26 to 64

67 to 77 85

5000 8000

9,13,18,25 (9,13,18,25) i.e. rating is inclusive of ballast consumption 160 (internal ballast, rating is inclusive of ballast consumption) 80,125,250,400,1000,2000 (93,137,271,424,1040,2085 ) 250,400,1000,2000 (268,427,1040,2105) 70,150,250 (81,170,276) 70,150,250,400,1000 (81,170,276,431,1060) 35,55,135 (48,68,159)

48 to 50

85

8000

3.7.1.2 De-lamping to reduce excess lighting De-lamping is an effective method to reduce lighting energy consumption. In some industries, reducing the mounting height of lamps, providing efficient luminaires and then de-lamping has ensured that the illuminance is hardly affected. De-lamping at empty spaces where active work is not being performed is also a useful concept. 3.7.1.3 Task Lighting Task Lighting implies providing the required good illuminance only in the actual small area where the task is being performed, while the general illuminance of the shop floor or office is kept at a lower level; e.g. Machine mounted lamps or table lamps. 3.7.1.4 Selection of High Efficiency Lamps and Luminaires Details of common types of lamps are summarised in table 3.14 below. From this list, it is possible to identify energy saving potential for lamps by replacing with more efficient types.

18

50

5000

High Pressure Mercury Vapour (HPMV) Metal Halide Lamps (Single ended) Metal Halide Lamps (Double ended) High Pressure Sodium Vapour Lamps (HPSV) Low Pressure Sodium Vapour Lamps (LPSV)

38 to 53

45

5000

51 to 79 62 to 72 69 to 108 90 to 133

70 70 25 to 60 --

8000 8000 >12000 >12000

Source : Best Practice Manual-Lighting : MEDA

122

123

Table- 3.15 Summarises the replacement possibilities with the potential savings. Table 3.15: Savings by Use of More Efficient Lamps
Lamp type Sector Existing Domestic/Commercial Industry GLS GLS GLS TL HPMV HPMV Replace by Watts 75 4 40 4 100 150 % 75 31 20 10 37 35 100 W *CFL 25 W 13 W *CFL 9W 200 W Blended 160 W 40 W TLD 36 W 250 W HPSV 150 W 400 W HPSV 250 W Power saving

Case study 46 : Conversion of High pressure mercury vapour lamp and Halogen lamp with High pressure sodium vapour lamp. Brief High pressure mercury vapour lamp of 250W & 400W capacity, halogen lamp of 500 W were used for street lighting in a manufacturing plant. 250W and 400W High pressure mercury vapour lamp used for street lighting could be replaced with 70W & 150W High pressure sodium vapour lamp respectively. 500W Halogen lamps used for street lighting and outside the factory could be replaced with 70W Highpressure sodium vapour lamp. Energy Saving Annual saving Investment Payback period : Rs.97,700/: Rs.20,000 : 3 months

Industry/Commercial

* Wattages of CFL includes energy consumption in ballasts.

(Source : Website of Bureau of Energy Efficiency)

Case study 44: Brief

Replacement of Incandescent lamps and blended mercury vapor lamps by compact fluorescent lamps (CFL)

Case study 47 : Replacement of filament type indicating lamps by LED type indicating lamps, assuming 0.8 as load factor: Brief In a refractory manufacturing unit, there were 150 nos of 10 W filament type lamps for indication purpose. These used to be glowing for 24 hrs for all the days of the year. It was consuming 1.2 kW. The total energy consumed was 10512 units on yearly basis. During the energy audit, it was decided that these can be replaced by LED type lamps consuming only 1 w power. After replacement by 10 nos of 1 W LED lamps, the total consumption became of 1051 units per year. The saving annually was observed of 9461 units, resulting in monetary saving of Rs 0.43 lakh per year (Rate of Rs 4.50 per unit). Energy Saving Annual Saving Investment Payback period : Rs.43,000/: Rs.15000/: 4 months

The lighting conversion efficiency of the incandescent lamp is 13.8 lumens per watt which is very low. Blended mercury vapor lamps of 160 W installed had much higher luminous intensity than required. Blended lamps were very inefficient and the lighting conversion efficiency was only 18 lumens per watt. Replaced incandescent and blended type mercury vapor lamps with CFL. Energy Saving Annual energy saving Investment Payback period : Rs. 2.07 Million : Rs. 1.24 Million : 8 months

Case study 45 : Utilization of natural light by installing translucent sheets for roofs in plant. Brief Fluorescent lamps were used to illuminate 100 rooms even during daytime, since natural lighting was not sufficient. Plant had already installed translucent sheets in many offices and wanted to install in other offices in a phased manner. Installed translucent sheets in the roofs to utilize natural lighting. After installing translucent sheets, lamps could be switched off for 8 hrs a day. Energy Saving Annual Saving Investment Payback period : Rs.21,500 : Rs.20000 : 11 months

3.7.1.5 Reduction of Lighting Feeder Voltage Fig. 3.7 shows the effect of variation of voltage on light output and power consumption for fluorescent tube lights. Similar variations are observed on other gas discharge lamps like mercury vapour lamps, metal halide lamps and sodium vapour lamps. Table-3.16 summarises the effects. Hence reduction in lighting feeder voltage can save energy, provided the drop in light output is acceptable.

124

125

Case Study 48 : Use of lighting voltage controller to reduce lighting energy consumption Brief A paper manufacturing plant has a connected lighting load of nearly 370 kW. This consists of fluorescent fittings, HPSV,HPMV & CFL lamps for plant, office and area lighting. The lighting load is fed from 3.3 kV bus by 4 nos. of LT transformers. These transformers have lighting loads apart from other loads. Each transformer is connected to a Lighting circuit Distribution box. The total actual load varies between 300 to 350 kW during night. Meters are fitted at each DB to measure power consumption. The voltage levels at lighting DBs vary between 225 & 240 V. Lighting loads consume less power at lower voltages. The installation of lighting voltage controllers, of different kVA, on each DB brought down the lighting consumption by 20%. The output voltages were set at 210 V. Energy Saving No. of DB lighting circuits Total Power consumption After installation Total Power consumption Annual Total energy savings Annual Cost savings Cost of Implementation Simple payback period : 4 : 338 kW : 275 kW : 0.245 Million kWh : Rs. 0.49 Million : Rs. 1.24 Million : 2 .5 years

Fig 3.7: Effect of Voltage Variation on Fluorescent Tube light Parameters Table 3.16 : Variation in Light Output and Power Consumption
Particulars Fluorescent lamps Light output Power input HPMV lamps Light output Power input Mercury Blended lamps Light output Power input Metal Halide lamps Light output Power input HPSV lamps Light output Power input LPSV lamps Light output Power input 10% lower voltage Decreases by 9 % Decreases by 15 % Decreases by 20 % Decreases by 16 % Decreases by 24 % Decreases by 20 % Decreases by 30 % Decreases by 20 % Decreases by 28 % Decreases by 20 % Decreases by 4 % Decreases by 8 % 10% higher voltage Increases by 8 % Increases by 8 % Increases by 20 % Increases by 17 % Increases by 30 % Increases by 20 % Increases by 30 % Increases by 20 % Increases by 30 % Increases by 26 % Decreases by 2 % Increases by 3 %

Case study 49 : Installation of Automatic Voltage Regulator (Energy Saver) in Lighting Circuit. Brief The lighting to the plant was provided mainly by discharge lamps like blended mercury vapour lamps, sodium vapour lamps and fluorescent lamps. In discharge lamps, the light output is roughly proportional to the input voltage. A reduction in voltage of about 5% does not cause a proportional reduction in light output. The light output is reduced marginally by 2%, but there is a substantial reduction of about 10% in power consumption. Similarly, a higher voltage does not give proportionally higher light output, but the power consumed is substantially high. The lighting & other electrical loads were segregated into different circuits and energy saver was connected to the lighting load only. The total lighting load worked out to 900 kW. Nearly 25% of lighting energy consumed could be saved by installing Energy Saver. Energy Saving Annual Energy saving Annual Saving Investment Payback period : : : : 7,68,960 kWh (considering 10% saving) Rs 3.5 Million Rs 3.2 Million 11 months

(Source : Website of Bureau of Energy Efficiency)

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3.7.1.6 Electronic Ballasts Conventional electromagnetic ballasts (chokes) are used to provide higher voltage to start the tube light and subsequently limit the current during normal operation. Table-3.17 shows the approximate savings by use of electronic ballasts. Table - 3.17 : Savings by use of Electronic Ballasts

Twilight switches can be used to switch the lighting depending on the availability of daylight. Care should be taken to ensure that the sensor is installed in a place, which is free from shadows, light beams of vehicles and interference from birds. Dimmers can also be used in association with photocontrol; however, electronic dimmers normally available in India are suitable only for dimming incandescent lamps. Dimming of fluorescent tube lights is possible, if these are operated with electronic ballasts; these can be dimmed using motorised autotransformers or electronic dimmers (suitable for dimming fluorescent lamps; presently, these have to be imported). Infrared and Ultrasonic occupancy sensors can be used to control lighting in cabins as well as in large offices. Simple infrared occupancy sensors are now available in India. However ultrasonic occupancy sensors have to be imported. In developed countries, the concept of tube light fixtures with in-built electronic ballast, photo-controlled dimmer and occupancy sensor is being promoted as a package. 3.7.1.9 Exterior Lighting Control Use a lighting control panel with time clock and photocell to control exterior lighting to turn on at dusk and off at dawn and turn non-security lighting off earlier in the evening for energy savings. Case study Brief 51 : Installing Photo Electric Controls in identified areas to control artificial lighting

Type of Lamp

With Conventional Electromagnetic Ballast

With Electronic Ballast

Power Savings, Watts

40 W Tubelight 70 W HPSV

53 81

42 75

11 6

(Source : Website of Bureau of Energy Efficiency) Electronic ballasts have also been developed for 20W and 65W fluorescent tube lights, 9W & 11W CFLs, 35W LPSV lamps and 70W HPSV lamps. These are now commercially available. Case Study 50: Brief No. of electronic blasts Hours/annum operation Energy Saving Annual Energy Saving through electronic ballast Annual additional saving due to reduced heat load on air-conditiong (kWh) Total annual energy saving Annual saving Investment Payback period : 8,83,200 kWh : 1,39,100 : : : : 10,22,300 kWh Rs 6.29 Million Rs 3.6 Million 7 months : 24000 : 2400 Use of Electronic Ballasts at Electrical Switchgear Manufacturing Plant

The lighting in the plant was mainly provided by fluorescent lamps. The shop areas were provided with north light in the roof which provided good lighting in the shop floor during day time when sky was clear. Apart from this, the machines were also provided with work lights. In spite of all these provisions the shop artificial lights were always switched on. Segregated lighting and fan circuits provided distribution boards exclusively for lighting. Installed photo electric switches to switch off light in identified areas. Energy Saving Annual Energy saving Annual saving Investment Payback period : : : : 43,800 kWh Rs.1,57,000/Rs.80,000/6 months

3.7.1.7 Low Loss Electromagnetic Chokes for Tube Lights The loss in standard electromagnetic choke of a tube light is likely to be 10 to 15 Watts. Use of low loss electromagnetic chokes can save about 8 to 10 Watts per tube light. The saving is due to the use of more copper and low loss steel laminations in the choke, leading to lower losses. 3.7.1.8 Timers, Twilight Switches & Occupancy Sensors Automatic control for switching off unnecessary lights can lead to good energy savings. Simple timers or programmable timers can be used for this purpose. The timings may have to change, once in about two months, depending upon the season. Use of timers is a very reliable method of control.
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Case study 52 : Providing Day Light Switches to control lamps in identified areas. Brief The process area of the plant was provided with enough lighting by means of Fluorescent Lamps. Fluorescent lamps were ON throughout the day. It was observed that translucent sheets were not provided in the roof.

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Installed Day Light Switches to switch off lamps and provided translucent sheets in the roof to get natural light in daytime. Energy Saving Annual Energy Saving Annual saving Investment Payback Period Case Study 53: Brief Conventionally, streetlight planning in a Municipal Corporation was not systematic - it was normally quantity based and not lighting design based. Photometric & Installation terms were totally ignored and the Selection criteria for Lamps & Luminaires ignored. The corporation realized the need for uniform & required level of illumination with increased energy efficiency. As a part of this innovation, they decided to develop street lighting on new roads in a scientific and systematic manner by implementing "Code of practice for lighting of Public thoroughfares IS 1944 (Part I & II), 1970". During different seasons street light ON / OFF timings are changed. • • • • The ON time varies from 6:00 pm during winters to 7:45 pm during summers. The OFF time varies from 7:15 am during winters to 5:30 am during summers. It is necessary to fix ON / OFF timings for the entire year according to sunset and sunrise timings. For this purpose annual programmable time switches are preferable rather than the conventional manual ones to switch ON & OFF exactly at the required timings throughout the year. : : : : 2,74,176 kWh Rs.11,67,990 Rs.68000/1 months

Energy Saving Annual Energy Saving Annual Saving Investment Payback period 3.7.1.10 T5 Fluorescent Tube Light The Fluorescent tube lights in use presently in India are of the T12 (40w) and T8 (36W). T12 implies that the tube diameter is 12/8" (33.8mm), T8 implies diameter of 8/8" (26mm) and T5 implies diameter of 5/8" (16mm). This means that the T5 lamp is slimmer than the 36W slim tube light. The advantage of the T5 lamps is that due to its small diameter, luminaire efficiencies can be improved by about 5%. However, these lamps are about 50mm shorter in length than T12 and T8 lamps, which implies that the existing luminaires cannot be used. In addition, T5 lamp can be operated only with electronic ballast. Case Study 54 : Use of T5 fluorescent lamps in Pharmaceutical industry Brief Prior to the installation of T5 lamps, the administration, Clean room and R&D areas of the plant were using T8 (36W) lamps. There were about 1500 lamps altogether. The lamps were having electromagnetic ballasts which consume about 12 watts/lamp. After consultations with the manufacturer of T5 tube lights, a deferred payment scheme was evolved where in the cost of the lamp will be repaid in 12 months. Warranty was also given for 12 months, during which if a lamp fails, free replacement is ensured. The price of one T5 lamp was Rs 875/-. Energy Saving Power consumption of 36w T/L Power consumption of 28 w T5 T/L Energy saving per T/L Annual energy saving Annual savings Investment Payback period 3.7.1.11 Lighting Maintenance Maintenance is vital to lighting efficiency. Light levels decrease over time because of aging lamps and dirt on fixtures, lamps and room surfaces. Together, these factors can reduce total illumination by 50 percent or more, while lights continue drawing full power. The following basic maintenance suggestions can help prevent this. • • • • Clean fixtures, lamps and lenses every 6 to 24 months by wiping off the dust. Replace lenses if they appear yellow. Clean or repaint small rooms every year and larger rooms every 2 to 3 years. Consider group re-lamping. : : : : : : : 48 W 29 W 19 W 0.13 Million kWh Rs 0.6 Million Rs. 1.2 Million 2 years : : : : 24400 kWh Rs.167100 Rs. 240 Million for 21 major roads 54 months

Street lighting modifications at Municipal Corporation

Almost 5 to 10% savings are achieved by using annual programmable time switch.
Parameter Pole height (m) Meters Mounting height Span between Poles Over hang (m) Meters Angle of Tilt (degrees) Wattage of Luminaries No. of poles No. of HPSV lamps Cost of Installations (Rs.) Annual Electrical Consumption (kWh) Average Illumination Before Implementation 8.5 to 10 7 to 8 30 1.5 to 3 15 250 33 66 7,57,100 74,500 Less than10 Lux After Implementation 8.5 to 10 10 42 0.9 to 1.25 5o-10 o 250 22 (33% reduction) 44 5,90,000 (22% saving) 50,100 (32.75% saving) 30 Lux with 40% uniformity
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3.8

Towards Energy Efficient Homes

Home uses of energy constitute the following: • • • • • For cooking (LPG, kerosene, electricity, biogas, biomass) For lighting (electricity, kerosene, biogas) For heating (electricity, kerosene, coal, biomass) For cooling (electricity, use of home gadgets) For transportation (petrol, diesel, electricity) Electricity

Energy saving can be achieved in homes and our day-to-day life by adopting the following simple measures. 3.8.2 • • • • • • • Lighting & Fans

3.8.1

Consumption level of some of the commonly used household electrical appliances is given in the following table-3.18. Table 3.18 : Electricity Consumption of Electrical Appliances
Appliances Instant Geyser Immersion Rod Air Conditioner Air Cooler Fan Refrigerator Electric Kettle Hot plate Oven Toaster Iron Incandescent Lamp Fluorescent Lamp Slim Tube Compact Fluorescent Lamp TV Vacuum Cleaner Desktop Cleaner Capacity 3000 Watt 1000 Watt 1500 – 2500 Watt 170 Watt 60 Watt 200/300/500 Watt 1000 – 2000 Watt 1000 – 1500 Watt 1000 Watt 800 Watt 750 Watt 100/ 60/ 40 Watt 40/ 20 Watt 36 Watt 7/ 9/ 11/ 13 Watt 180 Watt 800 Watt 120 Watt Consumption 3 units/ hour 1 unit/ hour 8.5 – 14.5 units/ day 1.7 units/ day 0.6 unit/ day 2/3/5 unit/ day 1 – 2 units/ hour 1 – 1.5 units/ hour 1 unit/ hour 0.8 unit/ hour 0.65 – 0.75 unit/ hour 0.5/ 0.3/ 0.2 unit/ day 0.28/ 0.15 unit /day 0.26 unit/day 0.06-0.09 unit/ day 0.2 unit/ hour 0.8 unit/ hour 0.13 unit/ hour

Use natural lighting during the day. Replace incandescent lamps with a CFL. Payback period of CFL assuming its cost as Rs. 110/- is less than 6 months. Switch off the light when not in use. Use 28W tubelight in place of 40W tubelight. Replace the conventional choke with electronic blast. Use electronic regulators for energy saving. Lubricate the fans regularly. Air-conditioner

3.8.3 • • • • • • •

Use stabilizer with air conditioner & act the voltage to 220 V. Clean the filters, condenser coils and thermostat at regular intervals. Avoid frequent opening of doors and windows. Avoid direct sunlight in the air conditioned space. Installation of reed screens in air-conditioners. Save Re. 1/- per hour by setting the room temperature to 250C. Purchase 'Star' rated energy efficient Air Conditioners only. Electric Water Heater

3.8.4 • • •

Change of heating element every 5 to 6 years. Set the thermostat at 50 0C to save power. Put on the water heater only 15 minutes before use. Refrigerator

3.8.5 • • • • • • •

Use stabilizer with refrigerator & set the voltage to 220 volt. Check the gaskit to avoid ingress of heat from outside. Avoid frequent opening of refrigerator door. Do not place the refrigerator in kitchen or congested area. Regular defrosting to avoid ice accumulation in the freezer. Cool the food before putting it in the refrigerator. Purchase 'Star' rated Energy Efficient Refrigerators only. Washing Machine

The following appliances typically can be attributed as electricity guzzlers: • • • • • • • Air conditioner Electric Water heater Refrigerator Washing machine Television Incandescent lamp Computer

3.8.6 • • • •

Using the machine at full load, the water consumption remains the same irrespective of load of clothes. Switch on the washing machine after loading. Put off the machine from the main switch after use. Same about 15%-20% of power by setting thermostat to 500C. Television

3.8.7 • •

Rational Use of Energy Rational use of energy does not mean that we sacrifice the need for comfortable existence. Rational use of energy strictly means to use the available energy more efficiently and avoid wastage of energy when a particular appliance is not in use. Energy saving potential in a typical house is 20%-25%. If the electricity bill is Rs. 2000/- p.m., one saves about Rs. 400/- p.m. by proper use of electrical appliances.
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Switch off the TV from the main switch and not through remote control. Don't leave TV on stand-by mode as it consumes around 80 watts of power even when not being viewed.

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3.8.8 Computers • • Switch on the computer when required to be used . Don't leave the computer in stand-by mode when not in use as in stand-by mode, it consumes 60 watts of power (monitor plus CPU) while no useful work is being done. Energy Audit Study Conducted by PCRA

3.9

D. Air Conditioning System: 1. Effectiveness of existing Units is only 64% and 8,10,000 kWh specific power consumption is high 2. Cooling water and chilled 1,20,000 kWh water is flowing in idle Units.

-Install Screw Chillers of 39.69 75.00 23 months total 600 TR capacity -Keep the idle Units isolated Immediate by closing the appropriate valves.

5.88

Nil

Case Study 55 : Energy Audit of a Bank's Head Quarter building in New Delhi Brief Punjab National Bank- with its beginning in April, 1895 at Lahore- is at present one of the foremost banks in India with a network of 4500 offices, serving more than 3.7 crore customers and having a business turn over exceeding Rs 1,94,000 crores. The focus areas during the Energy Audit were: 1.1 1.2 1.3 1.4 1.5 Review of Electricity Bills, Contract Demand & Power Factor Study of DG Set Study of Motor Loading Study of Illumination Study of Air Conditioning System References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.
4,23,420 kVAh 20.75 4.00 3 months -Monitor and Maintain Power Factor. - Connect capacitors through APFC (Automatic Power Factor Controller - Install capacitors of 800 kVAR. -The engine needs service. Consult the dealer or Immediate manufacturer - Replacing existing incandescent and 3 months halogen lamps with CFLs Replacing existing 2000 nos. of tube lights with 28 W T/L having electronic chokes.

Energy Savings
Sl Equipment / No. Observation Reason A. Load Management: 1. Power Factor is poor and is sometimes leading Expected Savings Expected Savings per annum per annum (kWh/kVAh, kL) (Rs in lakh) Expected Investment (Rs in Lakh) Payback Period Action Required

14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28.

B. DG Set: 1. Specific Power Generation of DG sets very low. C. Illumination: 1. Use of energy efficient lights Use of 28 W, T5 tube lights

12 kL of HSD

3.96

Minimal

11,497 kWh

0.56

0.14

2.

2,26,000 kWh

11.07

16.00

18 months

Designing with Light- A lighting Handbook - Anil Walia-International Lighting Academy Handbook of Functional requirements on Industrial Buildings-SP-32- Bureau of Indian Standards Energy Savings in Electric Motors : PCRA Energy Savings in Electric Furnaces : PCRA Energy Savings in Compressed Air System : PCRA Energy Savings in Pumps, Fans & Variable Speed Drives : PCRA Energy Savings in Refrigeration & Air Conditioning System : PCRA Energy Audit Reports of PCRA IS : 325 - "Three Phase Induction Motors - Specifications" IEC: 60034 (1to 18) - Rotating Electrical Machines IS : 4722 - Rotating Electrical Machines IS: 8789 - Values of Performance characterstics for Three-Phase Induction Motors IS : 12615 - Induction Motors :Energy Efficient Three-Phase squiral cagespeficiation IS : 13555 - Guide for selection & Application of Three-phase A.C. Induction Motors for different types of driven equipment. NEMA MG-1 : National Electrical Mnaufacturers Association, USA EEMA -19 : Energy Efficeint Indution Motors - Three phase - squiral cage Preformance, Selection & Application of Large A.C. Motors by Devki Energy Consultancy Pvt. Ltd., Vodadora Induction Machines by P.L. Alger Electrical Machies by M. Mostenko 'Industrial Furances' (Book), E.I. Kazantsev, Mir Publishers, Moscow. 'Handbook of Electrical Heating for Industry': C.James Erickson, IEEE Press The Institute of Electrical and Electronics Engineers Inc., (IEEE), New York 'Efficient Use and Management of Electricity in Industry' Devki Energy Consultancy Pvt. Ltd, Vadodara. 'Energy Audit Manual' (Series No.1) - 'Steel Foundary', National Productivity Council, New Delhi. 'BCIRA' Publication - UK 'Industrial Furnaces' W.Trinks - M.H. Mawhinney - John Wiley 'Induction Heating Handbook' John Davies & Peter Simpson - Mcgraw Hill Compressed Air System - A Guidebook on Energy and Cost Saving, E.M. Talbott, The Fairmont Press Inc., Zilburn, USA. Compressors-Selection & Sizing, Boyce & Brown, Gulf Publishing Co., Houstonne, USA

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29. 'Pump Hand Book'-I.J. Karassik, WC Krutzsch, W.H. Fraser, J.P. Messina, McGraw Hill International. 30. 'Analysis of Water Distribution Systems'- T.M. Walski CBS Publishers, Delhi. 31. Refrigeration and Air Conditioning' - W.F. Stoecker and J.W. Jones - Tata McGraw Hill. 32. 'Technology Menu for Efficient Energy Use'-National Productivity Council, India and Centre for Energy and Enviornmental- Studies of Princetonne University. 33. 'Good Practice Guide No. 2' - Energy Efficiency Office, Deptt. of Energy, U.K. 34. 'Energy Saving, with Adjustable Frequency Drive'- Allen Bradley Publication. 35. Saving Electricity in Utiltiy Systems of Industrial Plants, Devki Energy Consultacny Pvt. Ltd., Vadodara. 36. Industrial Refrigeration Handbook, Wilber F. Stoeker, McGraw Hill . 37. Refrigeration and Air conditioning, M. Prasad, New Age International (P) Ltd. 38. ASHRAE Handbooks, ASHRAE, Atlanta, Georgia, USA. 39. Cooling Tower Technology- Maintenance, Upgrading and Rebuilding, Robert Burger, The Fairmont Press Inc., Georgia, USA 40. Low-E Glazing Design Guide, Timothy E. Johnson, Butterworth Architecture. 41. Best Practice Manual - Electric Motors Transformers, Lighting : MEDA. 42. Energy Efficient Technologies for Industries, LBNL ,USA. 43. Bureau of Energy Efficiency-Course Material for Energy Manager/Auditor. 44. Websites/Product Information CDs of the following manufacturers: 1. www.energymanagertraining.com 2. Cromptonne Greaves Lighting Division 3. Bajaj Electricals 4. GE lighting, USA 5. Watt Stopper Inc, USA 6. Vergola India Ltd 7. Lighting reasearch centre, USA

Section 3 Energy Conservation in the Hydrocarbon sector
Ø Chapter - 4 Ø Chapter - 5 Ø Chapter - 6 Ø Chapter - 7

Refining Sector Exploration & Production LPG Bottling Plants Marketing Terminals/ Depots

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