1
ANSH ENERGY SOLUTIONS PVT. LTD.
[email protected]
COMPREHENSIVE ENERGY AUDIT REPORT of 6.6 MW
COGENRATION THERMAL CAPTIVE POWER PLANT
CLIENT: M/S Magnum Ventures Ltd., Shaibabad
June, 2010
Audit conducted by:
ANSH ENERGY SOLUTIONS PVT. LTD., Gayatri Dham, Lower
Bazar, Modinagar – 201204 (UP)
Auditor BEE Registration: EA-10465 (Anubhav Gupta) & EA-
3267(Anshul Singh Yadav)
Report No. AESPL/10-11/AG/12
i
Cont ent s
Acknowledgement ii
Audit firm and Audit Team Details iii
List of Abbreviations iv
Executive Summary v
Chapter 2: INTRODUCTION TO ENERGY AUDIT AND METHODOLOGY 1
2.1. Audit Objective and purpose of Energy Audit 1
2.2. Scope of Work 1
2.3. Methodology and approach followed 1
2.4. Time Schedule for Conducting the energy audit 2
2.5. Details of the Instruments used 2
2.6. Description of the Plant 2
2.7. Energy Consumption Profile and Energy Management System 3
2.8. Equipment and Major Areas for Energy Audit 5
2.10. List References 6
Chapter 3: Boiler
3.1 BACKGROUND 7
3.2 Operational efficiency of the boiler 7
3.3 Blow down losses 10
3.4 Blow Down Rate Estimation 10
3.5 Boiler Water Treatment 14
3.6 Boiler blow down heat recovery applications 14
3.7 Energy Saving by Flash steam recovery
3.8 Energy Saving by Flue gas heat impingement on feed stock conveyor
3.9 Energy Saving by re‐insulation of damaged areas
16
17
18
Chapter 4: Water Pumping 19
4.1 Background 19
4.2 Energy consumption pattern for pumps: 19
4.3 Observations & Recommendations 20
Chapter 5: Turbine 22
5.1 Background 22
5.2 Turbine Efficiency evaluation 22
5.3 Effect of Steam inlet pressure 24
5.4 Effect of Steam inlet temperature 25
5.5 Effect of exhaust pressure/ vacuum 26
Chapter 6: Condenser Cooling 28
6.1 Background 28
6.2 Cooling Tower 28
6.3 Observations 29
6.4 Conclusion Recommendation 30
Chapter 7: Electrical Systems and Motors 32
7.1 Background 32
7.2 Transformers 32
7.3 Power Factor Analysis 33
7.4 Loading pattern of motors 34
7.5 Motor Efficiency Calculation 36
7.6 Harmonic Measurement 38
7.1 Power Supply Quality 40
ii
A A C C K K N N O O W WL LE ED D G G E EM M E EN N T T
Investment Grade Energy Audit has been done with the objectives to identify & quantify the
energy saving opportunities for 6.6MW Cogeneration Captive Thermal Power Plant of M/S
Magnum Ventures Ltd., Shaibabad, Uttar Pradesh.
We would like to thank Shri Pradeep Jain, MD, Magnum Ventures Ltd., Mr. Ritesh Jain for
their giving us this opportunity and continuous support and encouragement during the
course of Energy Audit. We also the commitment of Shri Pradeep Jain and his team towards
cost reduction and energy conservation for betterment of the company and the environment.
We extend our gratitude towards Mr. Anil Bana, Head Power Plant, and entire power plant
team for their steadfast support extended to us during this study. We would like to convey
our special thanks to field staff for their inputs.
Energy Audit Team
Anubhav Gupta
Anshul Singh Yadav
Vikram Pal Singh
iii
Audit Firm and Audit Team Details
Ansh Energy Solutions Pvt. Ltd. is energy efficiency consultancy and practice areas are project
feasibility, DPR preparation, Impact assessment studies, monitoring and verification assignments as
independent evaluators, energy Audits, analyze the energy consumption and evaluate cost effective
opportunities to save electricity and fuels. We also undertake advisory services for industries related
to environmental aspects and works in the areas of Green Buildings, Climate change activities and
Sustainable development.
Ansh Energy Solutions Pvt. Ltd. is a professionally managed company with a team of full time
engineering professionals and Energy Auditors who are available to help and address clients specific
utility needs. Ansh Energy Solutions Pvt. Ltd. advices its clients on energy efficiency and energy
conservation plans, which are of paramount importance to them. The areas of our expertise in this
regard are:
a) Energy Audit
b) End Use Efficiency Improvement Programmes
c) Monitoring & Verification (M&V)
d) Energy Conservation Management plan
Audit Team
Anubhav Gupta, Director Ansh Energy Solutions Pvt. Ltd. Certified Energy Auditor from BEE having
experience of umpteen project implementations including, manufacturing facility setup, power plant
setups, refurbishing building envelopes, organization and coordination of various BEE seminars and
workshops. By qualification a Chemical Engineer from IT‐BHU, MBA in Sales and Marketing and a
certified Six Sigma Black belt he brings and all round experience of industry, institutions and
academics together in one place.
Anshul Singh Yadav Mechanical Engineer by basic qualification and MBA from the Management
Development Institute (MDI), Gurgaon, Certified B.O.E (Boiler Operation Engineer First class
proficiency) having over 12 years of hands on experience in in O&M of Power Plants and other
utilities. Power sector experience, spans in the diverse aspects of energy business from Plant
operations management, Maintenance planning, Fuel management and Strategic Planning, Plant
Commissioning, etc.
Vikram Pal Singh (PGDBM, BSc., DEE) is having 7 years of experience in energy audits, energy
efficiency projects, project management and training. His area of interest is green buildings and CDM
linked funding mechanism for Small size green projects.
iv
Abbreviations
ACs Air Conditioners
BEE Bureau of Energy Efficiency
CT Cooling Tower
ECO Energy Conservation Opportunity
EMP Energy Management Plan
M
3
/hr Cubic Meter Per Hours
FTL Fluorescent Tube Light Lamp
HPSV High Pressure Sodium Vapour
KVA Kilo Volt Ampere
KWH Kilowatt Hour
KVAH Kilo Volt Amperes Hour
KVAr Kilo Volt Amperes Reactive
KW Kilo Watt
LPD Litres Per Day
MW Mega Watt
O&M Operation and Maintenance
P.F Power Factor
PV Photo Voltaic
SPC Specific Power Consumption
STC Standard Test Condition
SWH Solar Water Heater
SQ. M. Square Meter
TR Ton of Refrigeration
V Volt
v
1.1. Brief Company Profile: Magnum Ventures Ltd, one of the largest paper manufacturing
mills of Northern India having installed capacity of 85000 TPA. This includes equal quantity of
Cream wove Paper, Maplitho, Copier, and Coated Duplex Board. The Company is having large
infrastructures 65000 Square Meter and Five Lacs Square feet Building Area in Sahibabad
Industrial Area, Ghaziabad (U.P.). This energy audit study was carried out for 6.6MW thermal
captive power plant of paper mill. This power plant was commissioned in the year 2004 as 4.4
MW unit and expanded to 6.6 MW in year 2008.
Power Plant comprises of 31 Tph, Thermax make, Bi‐drum, natural circulation, under bed,
balanced draft, atmospheric fluidisation bed combustion, bottom supported, and membrane
wall construction type of a boiler. Two sets of Trevani make turbo generator with 1st Turbine is
of 4.4 Mw extraction cum condensing type and 2nd Turbine is of 2.2Mw condensing Type and
other power plant auxiliary and power distribution system.
1.2. Scope of the audit study: The main objective of this exercise is to carry out specific energy
consumption analysis and make recommendations for reduction in auxiliary power, optimize
specific fuel consumption and to achieve a reduction in recurring expenditure on energy to
improve business viability by plugging the waste energy and through improvement in the
operational and maintenance practices of the facility. Major areas covered under energy audit
study of the Power Plant were Boiler and its auxiliaries, water pumping system, cooling towers,
motors and electrical distribution system.
1.3. Time Schedule for Conducting the energy audit
Field study – 4th June 2010 to 11th June 2010
Report Preparation – 12th June to 30th June
1.4. Energy Consumption and Energy Generation of the Plant:
The average daily power production is 1,30,000 units and monthly power production average is
of 39lacs unit of Power out of which 33.87lacs of unit is supplied to paper plant and rest 4.84 lac
units per month is the Auxiliary Power Consumption, break‐up of this auxiliary power is
graphically represented in following chart.
Figure: Share of different equipments in Auxiliary Power Consumption
59%
25%
11%
5%
Auxiliary Power Components
Pumps Boiler Auxiliary CT Fan Others
1. EXECUTIVE SUMMARY
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The major part of this auxiliary power is being consumed by water pumping system, followed by
Boiler auxiliaries like FD Fan, ID Fan, PA Fan and Coal handling system and Coal mill, around 11%
of the auxiliary power is being consumed by cooling tower fans and rest 5% is consumed by
remaining equipments and lighting load.
Table: Monthly Fuel Consumption, Steam & Power Production and Supply position
Month FEB March April May
Total Coal Consumption in Ton 6368 6200 6238 4969
Cost of Coal (in Rs.) 2,54,62,199 2,61,71,530 2,57,54,803 2,41,85,169
Total Steam Generation (in Ton) 25,103 25,283 24,994 26,169
Steam supply to Plant (in Ton) 13,236 13,353 13,067 13,141
Total Power Generated (KWh) 37,59,000 38,54,500 38,28,000 40,45,000
Power Supply to Plant (Kwh) 33,39,000 34,04,000 33,18,000 34,87,000
Fuel Cost per unit of Power (Rs/Kwh) 6.77 6.79 6.73 5.98
Cost of steam (in Rs/ton) 1014.31 1035.14 1030.44 924.19
Aux Power Consumption Kwh 420,000 450,500 510,000 558,000
Aux Power Consumption Ratio % 8.95 8.56 7.51 7.25
Summary of the Baseline Energy Consumption
1 Average annual electricity production 4,64,59,500 kWh
2 Average annual electricity supply to main Plant 4,06,44,000KWh
3 Average annual auxiliary power consumption 58,15,500KWh
4 Average annual steam generation 3,04,647Ton
5 Average Auxiliary Power consumption ratio 8.07%
6 Average annual Coal consumption for co‐generation 71325ton
7 Average heat rate of 4.4 MW turbine 4700Kcal/kg
8 Average heat rate of 2.2 MW turbine 2800Kcal/kg
9 Average Boiler Efficiency 80%
10 Average turbine cycle efficiency 4.4Mw 18.3%
11 Average turbine cycle efficiency 2.2Mw 30.2%
1.5. Major observations:
 Boilers
The method of performance assessment chosen for Boiler performance test is the indirect method
of heat loss and boiler efficiency as per BIS standard 8753. The test method employed is based on
abbreviated efficiency by loss method (or indirect method) tests, which neglects the minor losses
and heat credits.
The Boiler efficiency is observed as 80.91% against the 83 ±2% design efficiency, there is a margin of
about 2‐3% improvement by various measures, which are largely O&E related and R&M related.
About 1‐2% improvement is possible by various O&E related aspects such as providing improved
insulation at furnace, APH, Economiser, manhole doors and by providing internal lining of fire proof
cement on furnace doors. For further improvement in efficiency, R&M activities are required
especially in the area of super heater so that design parameters of super heated steam can be
vii
achieved; in this regard detail techno economic and cost benefit analysis is being carried out in
chapter on turbines.
Overall boiler water, CBD & Steam water quality & chemistry is observed within the prescribed limit
of OEM, however it was observed that parameters like O2, residual hydrazine, metal contents like
copper and iron and conductivity are not being monitored on regular basis.
CBD flow rate is observed in the range of 600‐900Liters/hr at temperature of 170 °C leaving scope
for heat recovery through flash steam recovery system.
Observed loss due to moisture in fuel is 0.86 % which can be brought down to a value of 0.20% detail
is discussed in 3.8 sections.
 Water Pumping System
Water pumping is vital energy consuming area in the power plant. Major pumps which were studied
in this report are:
¾ Condensate Extraction pumps
¾ Boiler feed water pumps
¾ RO/DM water plant pumps
¾ Make‐up/transfer pump
¾ Cooling water circulation pumps
¾ Raw water pumps
Total approximate energy consumption of pumping system = 10754 Kwh per day
Total auxiliary power consumption per day = 16200Kwh
Almost two third of the auxiliary power is consumed by water pumping system.
From the pump performance analysis based on the actual operating parameters we have observed
efficiency of 4.4MW turbine condenser cooling water pumps less than 60% which is on lower side.
There is no energy and flow meters installed for major pumps in the power plant
 Turbine
The average heat rate of 4.4 MW turbine is observed as 4700Kcal/kg and for 2.2MW turbine is
2800Kcal/kg with turbine cycle efficiency of 18.3% and 30.2% respectively. In absence of
performance GTR data it is difficult to identify deviation from that. It is also observed that steam
generated in the boiler is of specification 65kg/cm2 and Temperature 445°C against the design
temperature of 490°C ±5°C. An increase in inlet steam temperature, i.e., an increase in superheat at
constant inlet pressure and condenser pressure gives a steady improvement in cycle efficiency and
lowers the heat rate due to the increase in inlet temp and rising the inlet temperature also reduces
the wetness of the steam in later section of the turbine and improves internal efficiency of the
turbine.
If the turbine inlet steam temperature is increased to 490°C ±5°C as per the design conditions then
the heat energy input to the turbine will be increased and corresponding effect in cycle efficiency is
achieved @ 5.5% to 6.5% reduction in specific steam consumption for same amount of power
generated and turbine efficiency will improve by of 0.6% to 0.72%.
 Cooling Tower
¾ CT ‐1 range found to be 7.9 and CT‐2 range found to be 11.6 against design of 8
¾ CT‐1&2 approach found to be 10.73 and 8.8 against design 4 indicates, poor heat transfer.
¾ CT‐1 &2, effectiveness found to be 42.40% and 56.86% against design 66.66%, which indicates
poor heat transfer in CT.
viii
¾ Power measurements indicate under loading on CT fan motors and power factor is in the
range of 0.52 to 0.74. This is poor.
¾ In Cooling Tower ‐1, Fly ash & other foreign particles are presented in reasonable quantity at
most of the places like lowers, frills etc.
¾ As per the water quality concerned, makeup water quality is very good, here the scaling
chances in the system are very less but corrosion is taking place aggressively specially in MS
pipelines.
¾ At some places in cooling water piping system corrosion observed due to which water
leakage/seepage is existing.
¾ The corrosion in the system is suspected due to improper functioning of corrosion inhibitor
treatment. As PH in circulating water is around 8.5, Zn as corrosion inhibitor will not work
perfectly at higher PH. As Zinc will precipitate at higher PH & not inhibit the surfaces perfectly.
¾ Alkalinity in the makeup water is very less; treatment philosophy must be designed to take
care of low alkalinity system to control corrosion.
 Electrical system and motors
¾ There is no sub metering of the transformers and major equipments.
¾ The cumulative transformation capacity is 8500 KVA for 4300 MW (5625 KVA) Alternator.
¾ The earthing pits for transformer are not adequately spaced.
¾ The overall power factor of the plant is being maintained at above 0.93 lagging, but the power
factor of some of the individual feeders is below the satisfactory level.
¾ The motors of Main elevator 1&2, Reject elevator 1, Ash Handling Motor, and all cooling
tower fans are operating at less than 60% of loading.
¾ The average total voltage harmonic distortion is 6.45%.
¾ The average total current harmonic distortion is 9.3%.
¾ The variation between the terminal voltage and specified voltage is under 5% which is a
healthy sign.
1.6. Summary of recommendations and energy saving measures:
 Boilers
To carry out modification and retrofit in super heater section of Boiler in order to achieve design
parameter of main steam temperature of 490°C ±5°C will result in saving of 8 tons of coal per day
and will reduce loading on Boiler by almost 1.8TPH, and improvement in boiler insulation will result
in efficiency gain of 1% in boiler. The tentative investment for this work will be approximately INR
25,00,000/‐ and simple payback period of 58days.
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Energy and Fuel saving by installing Flash steam recovery system for Boiler Continuous Blow down
(CBD) the tentative saving of fuel through this measure should be 53580Kgs of coal and tentative
investment for installing this system will be of INR 4,50,000/‐ and simple payback period of 557days.
About 1‐2% improvement in boiler efficiency is possible providing improved insulation and re‐
insulation of damaged areas around, APH, Economiser, manhole doors, and at various other ducting
points need to be redone and by providing internal lining of fire proof cement on furnace doors cost
of this work is already taken in account in first point. The tentative saving from this step will be
saving of 500Ton per annum of coal consumption on account of improved boiler efficiency even if
1% gain in boiler efficiency is achieved. Resulting into monetary saving of INR27,50,000/‐.
Loss due to moisture in fuel is 0.86 % which can be brought down to a value of 0.20% by employing
method for fuel moisture removal through piping a portion of flue gases at stack temperature on to
the hooded conveyor of coal feed suing nozzles. Tentative investment for the duct and pipe work
should be INR 3,00,000/‐ and overall boiler efficiency gain of 0.66% will result in annual saving of
INR. 19,15,465/‐. Hence a simple payback period of 2 months.
 Water Pumping System
By replacing cooling water circulating pumps with the energy efficient pumps which will have less
specific energy consumption with respect to volume of water pumped and will give recurring energy
saving of 190,895units per annum if motor is also replaced by energy efficient class of Motors and
113,880 units if only pump is replaced and existing motors are utilised.
Payback period for proposed replacement of pumps in case‐1 is 87days and in case ‐2 is 146days.
Quotation in this regard is attached as annexure for your reference.
We also recommend installation of Flow and Energy meters for all major power consuming pumps
and observe flow and power pattern on regular basis (Shift and Daily basis). So that pumps having
deviation in specific power consumption can be identified by plant operation team.
 Cooling Tower
For energy savings and better air flow consider replacement of Aluminum alloy cooling tower fan
blades, with energy efficient FRP hollow fan blade. Estimated saving on account of each set of blades
replaced will of 52560Kwh in case ‐1 when both Fan and motor are replaced and 26280 Kwh in case ‐
2 when only fan blades are replaced with utilizing same motor. The investment for each set of blades
is of INR 85,000/‐ and simple payback period on account of saving through reduced recurring energy
consumption, for each set of fan blades replaced is 4months in case ‐1 when FRP Hollow Fan blades
are installed with new high efficiency motor and 8 months in case‐2 if only new set of FRP Hollow
Fan blades are installed with existing motor. Quotation in this regard is attached as annexure for
your reference.
Cooling tower fills needs to be checked for fill chocking and poor water distribution. Equal and
uniform water flow to each cell to be ensured for proper distribution of water as this will improve
effectiveness of Cooling Tower. Improved CT performance will allow to stop one CT fan during cold
weather conditions.
Monitor approach, effectiveness and cooling capacity for continuous optimisation efforts, as per
seasonal variations as well as load side variations.
A good chemical treatment with proper monitoring of the system will overcome all the water related
problems in the system and the corrosion in the system is suspected due to improper functioning of
corrosion inhibitor treatment. As PH in circulating water is around 8.5, Zn as corrosion inhibitor will
x
not work perfectly at higher PH. As Zinc will precipitate at higher PH & not inhibit the surfaces
perfectly, so consider organic treatment which will be a good option for corrosion control.
Corrosion rack must be installed on monthly basis to check corrosion rate (mpy) in the system this
system can be installed by cooling water treatment programme vendor at FoC.
 Electrical system and Motors
The earthing pits provided for transformer are also not adequately spaced. This causes the earthing
currents to either keep circulating in the system or is injected into the ground at various stages thus
increasing heat losses. Due to this a major amount of energy which is produced is not recorded in
the meters and a low efficiency is recorded. The proper earthing also enhances the protection relays
to function as per the design parameters and will improve system safety and reliability.
The installed capacitors need to be tested and relocated and some new capacitors need to added in
the system so that the plant transmission and distribution losses are reduced. The expected annual
savings from this measure should be approximately INR 36,44,160/‐. The tentative investment
required for purchase of capacitors of 750Kvar is INR 3,59,950/‐ and simple payback period of 1.2
months.
12 motors are recommended to be changed with proper rating of energy efficient motors as
suggested in following table:
Table: Techno economic analysis for replacement suggested motors
The capital investment required for replacing the above mentioned motors is INR 6,77,700/‐
The cumulative tentative annual saving in energy is 681959 KWH
The cumulative monetary saving should be INR 34, 09,797/‐
The cumulative simple payback period is 3 months
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 Summary of overall saving
The f ol l owi ng Tabl e presents the summary of vari ous energy conservati on
measures suggested after conducti ng the Energy Audi t of M/s Magnum Ventures
Power Pl ant Shai babad (UP)
SNO. ENERGY SAVING PROPOSAL
ANNUAL
SAVINGS
INVESTMENT
REQUIRED
SIMPLE PAY
BACK PERIOD
Rs. Rs. Months
1
R&M in super heater section of boiler
1,56,58,500 25,00,000 2
2
improving insulation for boiler and steam
piping and by providing internal lining of fire
proof cement on furnace doors
27,50,000
Nil
as cost of insulation is
considered in above
immediate
3
Flash steam recovery system for Boiler CBD.
294,690 4,50,000 18.5
4
Energy Saving by Flue gas heat
impingement on feed stock conveyor
19,15,465 3,00,000 2
5
Replacing cooling water circulating pumps
with EE Pumps Case‐1 when motor+ pump
both replaced
Case‐2 only pump replaced
9,54,475
227,560 3
5,69,400 227,560 5
6
Replace CT Fan blade by EE FRP hollow fan
Blades Case‐1 blade and motor both replaced
Case‐2 only fan blade replaced
15,76,800 5,10,000 4
7,88,400 5,10,000 8
7
Adequately spacing earthing pits of
transformer
8 Relocating and installing capacitors 36,44,160 3,60,000 1.2
9
Replacing 12 motors with high efficiency
proper size of motors
34,09,797 6,77,700 3
Total
2,90,30,412 50,25,260 2.1
Page 1
2 2. . I IN NT TR RO OD DU UC CT TI IO ON N T TO O E EN NE ER RG GY Y A AU UD DI IT T A AN ND D M ME ET TH HO OD DO OL LO OG GY Y
2.1. Audit Objective and purpose of Energy Audit
The main objective of this exercise is to carry out specific energy consumption analysis and make
recommendations for reduction in auxiliary power, optimize specific fuel consumption and to achieve a
reduction in recurring expenditure on energy to improve business viability by plugging the waste energy
and through improvement in the operational and maintenance practices of the facility.
2.2. Scope of Work
The aim and scope of audit is to quantify the fuel and energy consumption of the facility. It further aims
to identify the loss avenues in the systems and establish total and specific steam generation, boiler
efficiency monitoring, load balancing, run‐ability optimization and achieving best possible fuel to steam
ratio. The audit will thus cover parameter detection of:
1. Feed water inlet flow.
2. Blow Down flow estimation (If possible).
3. Inlet air temperature.
4. Temperature of exhaust to stack.
5. Feed water quality.
6. Cycle of concentration
7. Variance in phase loading of motors ACB’s and Transformer
8. Operation of motors
9. Losses due to poor capacitor behaviour or installation faults.
10. Load curves.
The completion of audit will achieve identification of all types of boiler losses and possible ECOs (Energy
Conservation Opportunities). It will highlight the efficiency improvement possibilities in motors,
capacitors and voltage variations.
The Audit has been done specifically for the steam generating unit, HVAC and Electricity Load
Distribution.
This inspection report reflects the conditions of the equipment at the time of the inspection only. Please
note that equipment conditions change with time and use and the conditions noted in this report may
change in appearance and severity as time progresses or with mishandling. Hidden or concealed defects
cannot be included in this report. An earnest effort was made on our behalf to discover all fallacies;
however in the event of an oversight no liability is acceptable. No warranty is either expressed or
implied. This report is not an insurance policy, nor a warranty service.
2.3. Methodology and approach followed
ANSH ENERGY SOLUTIONS PVT. LTD, conducted the investment grade energy audit study for the
6.6MW Cogeneration Captive Thermal Power Plant of M/S Magnum Ventures Ltd., Shaibabad,
Uttar Pradesh, during June, 2010. As a part of the study, the energy audit team visited the
Page 2
premises for undertaking performance assessment of various energy consuming equipments
installed in the building using sophisticated energy audit instruments. The following
methodology was adopted for successful conduct of the study:
• Monitoring of energy related parameters of various equipments using sophisticated and
portable energy audit instruments.
• Online measurement of operating data with various instruments.
• Collection of details regarding electricity consumption in the past, maximum demand and
power factor.
• Discussion with concerned officials to take note of energy conservation activities already
undertaken, if any.
• Critical analysis of data collected during field visit.
o Identification of opportunities having possible energy conservation potential and
quantification of energy losses.
o Identification of suitable measures for reducing energy consumption.
o Preparation of financial analysis for recommended measures.
2.4. Time Schedule for Conducting the energy audit
Field study – 4
th
June 2010 to 11
th
June 2010
Report Preparation – 12
th
June to 30
th
June
2.5. Details of the Instruments used
Following major instruments were used during the field study and data collection
1. Power and Harmonics Analyser
2. Ultrasonic Flow Analyser
3. Contact type and non‐contact type infrared temperature sensors
4. Anemometer
5. Lux meter
6. Oxygen Probe and Flue gas analyser
7. Distance meter
8. Contact type digital tachometer
2.6. Description of the Plant
Magnum Ventures Ltd. is a Paper Plant and Energy audit of its 6.6MW captive thermal power plant
was carried out in the month of June 2010.
The Magnum Ventures Power Plant is having following major Plant and Apparatus:
Boiler: Thermax make, Bi‐drum, natural circulation, under bed, balanced draft, atmospheric
fluidisation bed combustion, bottom supported, and membrane wall construction type of a boiler.
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This boiler is normally operated @ 35‐37Tph
Turbine: Plant is having two sets of turbo generator both of Trevani make 1
st
Turbine is of 4.4 Mw
extraction cum condensing type and 2
nd
Turbine is of 2.2Mw condensing Type.
Cooling Tower: Plant is having 2 Nos of Paharpur make 1200 m
3
/hr flow rate, induced draft cross flow
type of cooling towers.
Coal handling system: Magnum Ventures Power Plant receives coal through road and coal is stored in
yard. The process flow diagram is represented as under:
Yard Coal Breaking Screen Conveyer Screen Coal Crusher
Top Screw Main Elevator Screw Shoot Reject elevator
Bunker Coal Feeder
2.7. Energy Consumption Profile and Energy Management System
Table: Monthly Fuel Consumption, Steam & Power Production and Supply position
Month FEB March April May
Total Coal Consumption in Ton 6368 6200
6238 4969
Cost of Coal (in Rs.) 2,54,62,199 2,61,71,530
2,57,54,803 2,41,85,169
Total Steam Generation (in Ton) 25,103 25,283 24,994
26,169
Steam supply to Plant (in Ton) 13,236 13,353 13,067
13,141
Total Power Generated (KWh) 37,59,000 38,54,500
38,28,000 40,45,000
Power Supply to Plant (Kwh) 33,39,000 34,04,000 33,18,000
34,87,000
Fuel Cost per unit of Power (Rs/Kwh)
6.77 6.79 6.73 5.98
Cost of steam (in Rs/ton) 1014.31 1035.14 1030.44 924.19
Aux Power Consumption Kwh 420,000 450,500 510,000
558,000
Aux Power Consumption Ratio % 8.95 8.56 7.51
7.25
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Figure: Feed water consumption, Steam Generation and Process Steam supply
Figure: Power Production, Power Supply to Plant and Auxiliary Power Consumption
0
5000
10000
15000
20000
25000
30000
Feb/10 Mar/10 Apr/10 May/10
Steam Genration
Steam Supply to Plant
Feed Water Consumption
0
5,00,000
10,00,000
15,00,000
20,00,000
25,00,000
30,00,000
35,00,000
40,00,000
45,00,000
Feb/10 Mar/10 Apr/10 May/10
Prower Genrated
Power Supplied to Plant
Aux Power
Page 5
Figure: Auxiliary Power ratio and cost of Steam & Power
Figure: Share of different equipments in Auxiliary Power Consumption
2.8. Equipment and Major Areas for Energy Audit
Major areas of energy audit in Magnum Ventures Power Plant were Boiler and its auxiliaries, water
pumping system, cooling towers, motors and electrical distribution system. The objective of this audit
was to carry out specific energy consumption analysis and make recommendations for reduction in
auxiliary power.
0
1
2
3
4
5
6
7
8
9
10
Feb/10 Mar/10 Apr/10 May/10
Auxilary Power Ratio %
Cost of Steam Rs./kg
Cost of Power Rs./Unit
59%
25%
11%
5%
Auxiliary Power Components
Pumps Boiler Auxiliary CT Fan Others
Page 6
2.9. Energy Management Action Plan
2.10. References
¾ The Steam and Condensate Loop Book – Best practice guide to energy saving solutions
¾ Power Plant Engineering – P.K. Nag
¾ BEE Manual on Energy Efficiency testing (Book 4)
¾ Perry’s Handbook of Chemical Engineers (2003)
¾ Spirax Sarco website
¾ www.emerson.com
¾ www.lenntech.com/boiler‐feedwater.htm
¾ MCT31 Harmonic Calculation software and Energy Box energy savings calculation software
¾ Online turbine performance analysis by Engineering toolbox
Page 7
3 3. . B BO OI IL LE ER R
BOILER
3.1 BACKGROUND
The boiler of Magnum Ventures Power Plant is used to produce steam at the high pressure and
temperature required for the steam turbine that drives the electrical generator and extracted steam from
extraction cum condensing turbine is supplied to process plant used in paper manufacturing process. The
boiler has furnace, steam drum, mud drum, super heater coils, and economiser and air pre‐heaters.
The air and flue gas path equipment include forced draft fan(FD), PA Fan, induced draft fan (ID), air
preheaters (APH), boiler furnace, fan, fly ash collectors (electrostatic precipitators) and the flue gas stack.
Brief schematic diagram of a typical system is given below.
The brief specifications of this boiler are as follows:
Particulars Unit
Details at Normal Continuous
rating, NCR
Make Thermax
Type Water tube Bi‐drum
Capacity Tph 31
Main steam pressure Kg/cm
2
65kg/cm
2
Main steam temperature °C 490 ± 5°C
Boiler efficiency % 83 ± 2
Super heater outlet flow Tph 31
Coal calorific value‐GCV Kcal/kg 5680 (70%Coal and 30% Pet coke)
Coal consumption Tph NA
Total combustion air Tph
LTSH outlet temperature °C 340
Water‐economiser inlet temperature °C 125
Water‐economiser outlet temperature °C 185
Oxygen content at economiser outlet % 3.5
3.2 Operational efficiency of the boiler
The boiler efficiency trial was conducted to estimate the operational efficiency under as run conditions.
The efficiency evaluations, by and large, follows the loss components mentioned in the reference
standards for boiler testing at site using indirect methods mentioned in BS 845:1987 as amended on date.
The method of performance assessment chosen is the indirect method of heat loss and boiler efficiency
as per BIS standard 8753. The test method employed is based on abbreviated efficiency by loss method
(or indirect method) tests, which neglects the minor losses and heat credits. The major losses covered
are:
• Heat loss due to dry flue gas losses.
• Heat loss due to moisture in fuel
• Heat loss due to moisture in air.
• Heat loss due to hydrogen in fuel
Page 8
• Heat loss due to un‐burnt carbon in fly ash and bottom ash.
• Heat loss due to radiation to be assumed depending on emissivity of surface
• Unaccounted losses as declared by the boiler supplier
Following formula are used for estimation and calculation of Losses by indirect method:
a. Calculation for Dry Flue gases:
b. Heat loss due to dry flue gas
This is the greatest boiler loss and can be calculated with the following formula:
Page 9
c. Loss due to un‐burnt carbon in ash, L
uca
Loss due to un‐burnt carbon in ash, L
uca
=
d. Loss due to moisture in fuel, L
mf
Loss due to moisture in fuel, L
mf
= M*[(0.45*(FGT‐ABT)) + 584]
GCV of Fuel
Where:
M = is kg of moisture in 1 kg of fuel
Cp = Specific heat of superheated steam in kCal/kg°C
FGT = Flue gas temperature in °C
ABT = Ambient temperature in °C
584 = Latent heat corresponding to partial pressure of water vapour
e. Loss due to hydrogen in fuel, L
hf
Loss due to hydrogen in fuel, L
hf
= 9*H
2
* [(0.45 * (FGT‐ABT)) + 584] * 100
GCV
Where
H
2
is kg of H
2
in 1Kg of Fuel
f. Loss due to moisture in air, L
ma
Loss due to moisture in air, L
ma
= AAS*humidity*0.45*(FGT‐ABT)*100/GCV
Where
AAS = Actual mass of air supplied
Humidity = Humidity of air in kg/kg of dry air
g. Radiation and un‐accounted losses these losses considered as given in PG test/Design
documents.
Alternatively, the radiation losses can be estimated by measuring the surface temperatures and
surface areas of the boiler section.
Normally surface loss and other unaccounted losses are assumed based on type and size of the
boiler as given below.
For industrial fire tube / packaged boiler = 1.5 to 2.5%
L
uca
= CV of carbon in Kcal/kg * [(C%FA*F
Ash
) + (C% BA* B
Ash
)]
GCV of Fuel Kcal/Kg
Where
C% BA ‐ % of Carbon in Bottom Ash
C%FA ‐ % of Carbon in fly ash
B
Ash
– Bottom ash quantity in Kg/Kg
F
Ash
– Fly ash quantity in Kg/Kg
Page 10
For industrial watertube boiler = 2 to 3%
For power station boiler = 0.4 to 1%
These losses can be calculated if the surface area of boiler and its surface temperature are known as
given below:
L
G
= 0.548 X [{T
S
/55.55}
4
] + 1.957 X (Ts‐Ta)
1.25
X √V
m
Where
L
G
= Radiation loss in watts/m
2
V
m
= Wind velocity in m/s
T
s
= Surface temperature (°K)
T
a
= Ambient temperature (°K)
3.3 Blow down losses :
Dissolved salts find entry to the boiler through make‐up water which is continuously fed by the Boiler
Feed Water pump ( bfw). In the boiler, there is continuous evaporation of water into steam. This leaves
behind the salts in the boiler. Concentration of these salts, tend to increase in the boiler drum and starts
precipitation after certain concentration level.
Water from the drum should be blown down to prevent concentration of salts beyond certain limits.
Since the water in the boiler drum is at a high temperature (equivalent to it's saturation temperature at
boiler drum pressure), excess blow‐down will lead to loss of energy known as 'blow‐down losses'.
Blow‐down rate reduces the boiler efficiency considerably as could be seen from the figure. Hence it is
imperative that blow‐down rates are optimized, based on the hardness levels of boiler drum water which
is a function of the operating pressure.
In boiler operation practice, rate of blow down increases with steam pressure as the scaling tendency
increases with high temperature because the hardness limits are very stringent. While figure gives an
estimate of % blow down on losses, the same may be calculated from the hardness levels of make‐up
water , flow rate ,steam generation rate and the hardness level of drum water (observed).
Model given below could be used to determine the maximum limits of TDS (total dissolved solids) that
could be tolerated in the boiler drum operating at various pressures. The correlation is based on
American Boiler Manufacturers' Association code of practice.
However, if the limits stipulated by the Boiler Designer are less than this value, the lower of the two must
be taken as the tolerance limit.
Where TDS is the permissible Total Dissolved Solids in ppm at the boiler drum and Pr is the drum pressure
in psig.
The quantity of blow down to maintain the given status of boiler water in terms of TDS is determined by
the material balance of solids across the boiler drum as given in the figure below.
3.4 Blow Down Rate Estimation :
For estimating the boiler drum blow down rates, following nomenclatures are used.
Let
F = feed water in t/hr
C
m
= Concentration of TDS in make‐up water in ppm
C
f
= Concentration of TDS in feed water in ppm.
C
b
= Concentration of TDS in blow‐down water
m = weight fraction of make‐up water in feed water.
Page 11
Figure: Impact of Blow down Rate of fuel loss.
For establishing the blow‐down rate, a material balance on TDS is developed as shown.
TDS balance:
W
bd
* C
b
= F * m * Cm ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐i
F = W
s
+ W
bd
‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ii
Therefore equation i may be written as
Wbd * Cb = ( Ws + Wbd) * m * Cm ‐‐‐‐‐iii
Page 12
If C
f
is the TDS present in the combined feed water to the boiler, above equation may be written as
W
bd
* C
b
= ( W
s
+ W
bd
) * C
f
‐‐‐‐‐iv
If more than the required quantity (i.e W
bd
t/hr) is blown down, the excess quantity will result in
lower boiler efficiency . Hence, it is imperative that boiler blow down rate is monitored continuously
for achieving high boiler efficiency. An optimal blow down rate may be calculated taking into
consideration the impact of high TDS on poor heat transfer vs boiler efficiency.
Table : Data Sheet for Boiler efficiency evaluation
Parameters Unit Design As run
data
Duration 0900hrs to 1500hrs 07‐
06‐2010
Hr
Average Unit Load Tph 35.54
% of NCR 114.65%
Coal Consumption Kg 35000
Ambient parameters
Dry bulb temperature °C 35
Wet bulb temperature °C 21.1
Relative humidity % 42.8
Moisture content in air Kg/kg
of air
0.014
Coal Parameters – Ultimate
Analysis
Carbon (C) % 58.96
Hydrogen (H) % 7.16
Sulphur (S) % 0.56
Nitrogen % 2.02
Oxygen % 9.88
Total moisture (H
2
O) % 7.43
Ash % 13.99
Gross calorific value Kcal/kg 5491
Steam Parameters
Main steam flow Tph 35.54
Main steam pressure Kg/cm
2
65.09
Main steam temperature °C 446.41
Air/Flue gas parameters (APH
inlet)
Oxygen content at inlet % 2.8
Flue gas temperature at inlet °C 205.6
Air Temperature at inlet °C 32
Air/Flue gas parameters (APH
outlet)
Flue gas temperature at outlet °C 153.27
Oxygen content at outlet %
Air temperature at outlet °C 155
Oxygen content at ID fan inlet % 3.7
Carbon content in fly ash % 4
Carbon content in bottom ash % 8
Bottom ash quantity (dry basis) Kg/kg of Coal 0.3
Fly ash quantity (dry basis) Kg/Kg of Coal 0.7
Page 13
The Boiler efficiency calculations are given in following table:
Table: Boiler efficiency calculation for trial run period on 07
th
June 2010 by direct method
S.No.
Feed water
supplied
(ton)
Steam
Produced
(ton)
Fuel
Fired (kg)
Moisture
content
in Fuel
(%)
Time
Duratio
n
(Hours)
Dry fuel
weight
available
Fuel
Calorific
value
(kcal/kg)
Available
energy (gcal)
Energy
attained in
steam at
65kg/cm2
Overall
Efficienc
y
1 217 212 35000 5.8 4 38220.0 5491 209866.02 166976.50 79.56%
Table: Steam & Power Production, Plant fuel rate and Boiler efficiency calculations
Date
Feed water
consumption
(ton)
Steam
Production
(ton)
Coal
Consum
ption
Power Generated
(units)
Overall
plant
fuel rate
kg/kWh
Boiler
Efficiency
4.4MW 2.2MW Total
06‐06‐2010 914 890 139 91000 44000 135000 1.03 79.25%
07‐06‐2010 872 847 136 93000 37000 130000 1.05 77.08%
08‐06‐2010 916 893 141 99000 38000 137000 1.03 78.39%
09‐06‐2010 822 796 125 89000 34000 123000 1.02 78.82%
10‐06‐2010 927 900 142 101000 39000 140000 1.01 78.44%
Table: Efficiency evaluation of Boiler by indirect method during trial run period on 07
th
June 2010
Parameters Unit
Design
Value
Actual
Value
%
Deviation
Load Ton
Fuel GCV Kcal/Kg 5491
loss due to dry flue gases, L
dfg
% 5.52
Loss due to Hydrogen in Fuel % 7.49
Loss due to moisture in air % 0.15
Loss due to unburnt carbon in ash,
L
uca
%
0.67
Loss due to moisture in fuel, L
mf
% 0.86
Radiation Loss % 2.2
Unaccounted loss and
manufacturers margin
%
Na
Heat loss due to blowdown % 1.4
Loss due to furnace door draft % 0.8
Total Loss 19.09%
Boiler Efficiency (1‐Total Loss) % 83 ± 2% 80.91% 0.09%
The heat loss profile covering losses through unburnt in ash, sensible heat loss in flue gases,
moisture in combustion air, loss due to presence of hydrogen and moisture in coal, radiation and
unaccounted loss, are represented in above table. Above trial data is average value during 30 min.
interval.
It may be observed that as against 83% design efficiency, there is a margin of about 2‐3%
improvement by various measures, which are largely O&E related and R&M related. About
1‐2% improvement is possible by various O&E related aspects such as providing improved insulation
at furnace, APH, Economiser, manhole doors and by providing internal lining of fire proof cement on
furnace doors. For further improvement in efficiency, R&M activities are required specially in the
Page 14
area of super heater so that design parameters of super heated steam can be achieved, in this
regard detail techno economic and cost benefit analysis is being carried out in chapter on turbines.
3.5 Boiler Water Treatment
Water quality influences the performance of boiler internals. As energy auditors we observed
the present water treatment parameters pertaining to:
Type and rated capacity
Operating capacity of the internal and external treatment methods
Water quality parameters
Control of blow down (CBD & IBD)
Condensate polishing
Table: DM water, feedwater, CBDand Steam parameters as on 04
th
June 2010
Particulars Unit MB Feed water CBD Steam
Ph 6.5 9.0 9.5 8.5
P Alk ppm Nil 1.0 6.0 1.0
T Alk ppm 3.0 5.0 12 4.0
Total Hardness ppm Nil nil Nil nil
Chlorides ppm 4.0 4.2 6.3 4.0
TDS ppm 0.0 2.6 23.3 1.6
: DM water, feedwater, CBDand Steam parameters as on 01
st
June 2010
Particulars Unit MB Feed water CBD Steam
Ph 6.5 9.0 9.5 8.5
P Alk ppm nil 1.0 5.0 1.0
T Alk ppm 4.0 5.0 10 4.0
Total Hardness ppm nil nil nil nil
SiO
2
ppm ‐ 0.02 1.3 0.02
Chlorides ppm 4.2 4.2 6.3 3.5
TDS ppm 0.0 2.6 23.3 1.6
Observations
¾ Overall boiler water, CBD & Steam water quality & chemistry is observed within the
prescribed limit of OEM, however it was observed that parameters like O
2
, residual
hydrazine, metal contents like copper and iron and conductivity are not being
monitored on regular basis.
¾ CBD flow rate is observed in the range of 600‐900Liters/hr at temperature of 170 °C
leaving scope for heat recovery through flash steam. The amount of flash steam which
can be released by the CBD water blow down flow rate of 600Kg/hr at 1 bar g would be
199.3 kg/h of flash steam.
¾ This flash steam recovery will reduce load on DM plant by 200Kg/hr as pure water can
be recovered by installing Boiler continuous blow down (CBD) heat recovery system.
3.6 Boiler blow down heat recovery applications
Continuous blow down of boiler water is necessary to control the level of TDS (Total Dissolved
Solids) within the boiler. Continuous blow down lends itself to the recovery of the heat content of
the blow down water and can enable considerable savings to be made.
Page 15
Boiler blow down contains massive quantities of heat, which can easily be recovered as flash steam.
After it passes through the blow down valve, if the lower pressure water flows to a flash vessel. At
this point, the flash steam is free from contamination and is separated from the condensate, and can
be used to heat the boiler feed tank/condensate tank or can be supplied back to Deaerator tank (see
Figure for a typical application of flash steam recovery system).
The residual condensate draining from the flash vessel can be passed through a plate heat exchanger
in order to reclaim as much heat as possible before it is dumped to waste. Up to 80% of the total
heat contained in boiler Continuous Blow Down can be reclaimed in this way.
Figure: Typical heat recovery system from boiler blow down
Consider the CBD water and process plant condensate is being discharged to a flash vessel
pressurized at 1 bar g and at temperature of 170°C. If the return line were connected to a vessel at a
pressure of 1 bar g, then it could be seen from steam tables that the maximum heat in the
condensate at the trap discharge would be 505 kJ/kg and the enthalpy of evaporation at 1 bar g
would be 2201 kJ/kg.
The proportion of the condensate flashing off at 1 bar g can then be calculated as follows:
Heat in condensate at 4 bar g = 640 Kj/kg
At 1 bar g saturated condensate can only hold = 505 Kj/Kg
Surplus heat in saturated condensate at 1 bar g = 135 Kj/kg
Heat in steam at 1 bar g = 2201 Kj/kg
Proportion of flash steam = 135 Kj/kg/ 2201 Kj/Kg
Proportion of flash steam from the condensate = 0.061 (6.1%)
In this case, if the equipment using steam at 4 bar g were condensing 15000 kg/h of steam, then the
amount of flash steam released by the condensate at 1 bar g would be 0.061 x 15000 kg/h = 919.5
kg/h of flash steam.
Therefore, the amount of flash steam produced can depend on the type of steam trap used, the
steam pressure before the trap, and the condensate pressure after the trap.
Similarly for CBD water flash recovery
Page 16
The proportion of the condensate flashing off at 1 bar g can then be calculated as follows:
Heat in condensate at 64 bar g = 1236 Kj/kg
At 1 bar g saturated condensate can only hold = 505 Kj/Kg
Surplus heat in saturated condensate at 1 bar g = 731 Kj/kg
Heat in steam at 1 bar g = 2201 Kj/kg
Proportion of flash steam = 731 Kj/kg/ 2201 Kj/Kg
Proportion of flash steam from the condensate = 0.332 (33.2%)
In this case, if the CBD water at 64 bar g were released @ 600 kg/h of saturated water, then the
amount of flash steam released by the condensate at 1 bar g would be 0.332 x 600 kg/h = 199.3 kg/h
of flash steam.
Flash vessels are used to separate flash steam from condensate. Following Figure shows a typical
flash vessel constructed in compliance with the European Pressure Equipment Directive 97/23/EC.
After condensate and flash steam enter the flash vessel, the condensate falls by gravity to the base
of the vessel, from where it is drained, via a float trap, usually to a vented receiver from where it can
be pumped. The flash steam in the vessel is piped from the top of the vessel to any appropriate low
pressure steam equipment.
Figure: A typical flash vessel
3.7 Energy Saving by Flash steam recovery
Energy and Fuel saving through Flash steam recovery can be calculated as under:
Page 17
The heat requirement for increasing the temperature of 199kg of cold make‐up water by 140°C
(fresh make up water temperature as 30°C and flash steam temperature of 170°C), by using
following Equation
Where:
Q = Quantity of energy (kJ)
m = Mass of the substance (kg)
c
p
= Specific heat capacity of the substance (kJ/kg °C)
ΔT = Temperature rise of the substance (°C)
In our case m is 199Kg; ΔT is the difference between the cold water make‐up and the temperature of
returned flash steam from CBD water; c
p
is the specific heat of water at 4.19 kJ/kg °C.
199 kg x 4.19 kJ/kg °C x 140°C = 116733.4 kJ/kg
Basing the calculations on an average for a plant in operation 8 400 h/year (350 days of operation),
the energy required to replace the heat in the make‐up water is:
116733.4 kJ/kg x 8 400 h/year = 980 560.56 GJ/year
Or 27900Kcal/kg X 8400 h/year = 234360 Gcal/year
If the average boiler efficiency is 81%, the energy supplied to heat the make‐up water is:
2S4S6u ucal¡yeai
u.81
= 289SSS.SS uCal¡yeai
Amount of Fuel saved considering calorific value of coal as 5400Kcal/kg = 53580Kgs
Cost of fuel saved per year considering cost of coal as Rs 5500 per ton – Rs. 294,690/‐
Cost of installing flash heat recovery system for continuous blow down shall be Rs 4.5 lacs
Simple payback period is 1.53 years or (557 days/ 80 week)
3.8 Energy Saving by Flue gas heat impingement on feed stock conveyor
Observed loss due to moisture in fuel is 0.86 % which can be brought down to a value of 0.20%.
The easiest method for fuel moisture removal is piping a portion of flue gases at stack temperature
on to the hooded conveyor of coal feed suing nozzles.
A picture for example of fuel heating and moisture removal is attached below.
The saving of 0.66% amounts to ‐ 0.66% x Rs. 24185169 (May Consumption) = Rs. 1,59,622
Thus the annual savings are 1,59,622 x 12 = Rs. 19,15,465/‐
Tentative investment for the duct and pipe work = Rs. 3,00,000/‐
Hence a simple payback period = (300000/1915465) x 12 = 1.87 Say 2 months
Page 18
3.9 Energy Saving by re‐insulation of damaged areas
The damaged insulation at Economizer and APH ducts and at various other ducting points need to be
redone. The reduction in radiation loss will be from 2.2% to standard 1%
Thus the savings will be = 1.2% i.e. 1.2% x Rs. 24185169 (May Consumption) = Rs. 290222 monthly or
Rs. 34,82,664/‐ annually.
The cost for insulation work is Approx. 10 lacs and the simple payback comes to 10/34.82 = 3.44 or
say 4 months.
The final savings are as below:
a) Savings due to Blowdown flash heat recovery = 0.4%
b) Savings due to Moisture in fuel = 0.66%
c) Savings due to radiation reduction = 1.2%
d) Savings due to Furnace door drafts = 0.6%
Hence the boiler efficiency will be improved in total by 2.86%
Page 19
4 4. . W WA AT TE ER R P PU UM MP PI IN NG G
Water Pumping
4.1 Background
Water pumping is vital energy consuming area in the power plant. Major pumps in Magnum
Ventures Power Plant are:
Condensate Extraction pumps
Boiler feed water pumps
RO/DM water plant pumps
Make‐up/transfer pump
Cooling water circulation pumps
Raw water pumps
4.2 Energy consumption pattern for pumps:
The daily energy consumption by pumping system is as follows:
Sno. Equipment Instantaneous KW Daily Consumption KWh
Submersible pump 1 24.31 583
Submersible pump 2 15.3 367
Submersible pump 3 18.8 451
HP 2‐1 RO 15.34 276
HP 1‐1 RO 15.8 284
HP 1‐2 RO 10.96 197
HP 2‐2 RO 10.3 185
Boiler Feed Pump 1 160 3840
Boiler Feed Pump 2 148 3552
2.2 MW
CT Pump 1 41.8 1003
CT Pump 2 42.6 1022
CT Pump 3 0
CEP 1 10.1 242
CEP 2 0
4.4 MW
CT Pump 1 50.3 1207
CT Pump 2 46.6 1118
CT Pump 3 0 0
CEP 1 11 264
Total Kwh/Day 10754
Total energy consumption of pumping system = 10754 Kwh per day
Total auxiliary power consumption per day = 16200Kwh
Page 20
Almost two third of the auxiliary power is consumed by water pumping system.
Table: Design, operating parameters and efficiency of pumps
Description of
Pump
Pump Specification
Measured
Paremeters
Power
input by
Motor
in KW
Motor
Efficiency
Pump
efficiency
Make
Q(flow)
in
m
3
/hr
Head
in
Meter
Motor
KW
RPM Flow
Discharge
Pressure
in kg/cm
2
BFP-1 KSB 40 850 137 2980 42 80 160 88.3% 64.5%
BFP-2 KSB 40 850 137 2980 40 85 148 90.5% 68.9%
Transfer Pump Grundfos 45 50.7 11 2900 24.5 5.5 6.5 90.0% 62.5%
CEP-1 (4.4 MW) KSB 12.1 89 12.1 2900 12.8 8.8 9 85.9% 52.1%
CEP-1 (2.2 MW) Sulzer 13.5 90 9.7 2920 13.6 8.8 8.1 84.9% 55.8%
I
ST
RO HP Pump-1 Grundfos 21 207 15 2920 20 14 15.8 87.2% 65.1%
I
ST
RO HP Pump-3 Grundfos 21 207 16 2920 19 14 15.34 87.2% 63.9%
2
nd
RO HP Pump-2 Grundfos 17 135.6 11 2920 17 13 10.96 84.2% 65.0%
2
nd
RO HP Pump-3 Grundfos 17 135.6 11 2920 17 13 10.3 86.5% 67.3%
CT Pump-1 (4.4) NA NA NA NA 1440 400 2.2 50.3 85.8% 55.3%
CT Pump-2 (4.4) NA NA NA NA 1440 390 2.2 46.6 83.9% 58.6%
CT Pump-1 (2.2) NA NA NA NA 1440 380 2.2 41.8 73.3% 74.0%
CT Pump-2 (2.2) NA NA NA NA 1440 390 2.2 42.6 69.4% 78.7%
Raw Water Pump-1
32 2 3.6 82.0% 61.7%
Observation
From the pump performance analysis based on the actual operating parameters we have
observed efficiency of 4.4MW turbine condenser cooling water pumps on lower side.
There is no energy and flow meters installed for major pumps
In case of pumping system pump efficiency as per industry standards is considered as
Normal ‐ 60 – 75%
Best ‐ 78 ‐‐ 80% (upto 89% efficiency in case of horizontal split casing pumps)
Worst ‐ 30 – 60%
(Reference: CII‐LM Thapar Centre for Competitiveness for SMEs)
Recommendation
We suggest replacing cooling water circulating pumps with the energy efficient pumps which will
have less specific energy consumption and will give recurring energy saving of 190,895units if
motor is also replaced by energy efficient class of Motors and 113,880 units if only pump is
replaced and existing motors are utilised.
Payback period for proposed replacement of pumps in case‐1 is 87days and in case ‐2 is 146days.
We also recommend installation of Flow and Energy meters for all major pumps and observe flow
and power pattern on regular basis (Shift and Daily basis). So that pumps having major power
consumption can be identified.
Page 21
Table: Saving potential and cost analysis for replacing circulating cooling water pumps with new energy efficient pumps
Parameters
Present
Pumping
System
Proposed Pumping System
Case‐1
With New Motor
Case ‐2
With existing motor
Pump Specifications
No. of Pumps 2+1 and 2+1
Replace 2+2 by EE Pumps &
EE Motors
Replace 2+2 Pumps only and
utilise existing motors
Pump Type Hori Hori. B.P.O. Hori. B.P.O.
Capacity NA 450m3/hr 450m3/hr
Total Head 20mtrs 20mtrs 20mtrs
Efficiency 86% 86%
BKW at Shaft NA 22.57 22.57
Required Motor 45KW 30 KW 30 KW
Energy Consumption 41‐51Kw
25.2KW at 80% loading and
95% efficiency motor
With present motor efficiency
projected motor load 30 to 35 KW
Energy consumption per
day
1128KWh 605Kwh 816Kwh
Annual Energy Saving Nil 190895Kwh 113880Kwh
Saving in recurring
Energy cost per annum
(@Rs5/Kwh)
Nil 9,54,475 INR 5,69,400 INR
Cost of New Pumps 227,560/‐ INR for 4 Pumps @56890.00 each pump
Simple pay back 3months (87Days) 5months (146Days)
Note:
Quote for new energy efficient pump is attached as annexure for your reference.
Cost of motor is not considered in above scenario as it is worked out in Electrical & motor chapter.
For the pump used in above example calculating power requirement
450m
3
/hr = 125l/s Powcr obsorbcJ =
125Ips x 9.81
m
s2
x15m
0.86 x 1000
=21.38Kw (approx)
Therefore Motor input power will be 21.38/0.95 = 22.51Kw
Therefore annual running cost = 22.51Kw x 24h x 350 day x Rs 5/Kwh = INR 945,420/-
The approximate costs to an industrial purchaser are as follows:
Bare shaft pump alone INR 56,000/-
Or
Pump + Motor INR 1,37,000/-
Running costs for pump lifetime say 20 years = INR 1,89,08,400/- at present energy cost.
Comparing above costs with the running costs of pump during lifetime
Initial capital cost of pump + motor - 1.5%
Maintenance Costs - 2.5%
Running costs - 96%
The main conclusion to be drawn from these figures is that running costs far outweigh capital costs and should be
considered far more important when specifying new equipment. Pumps and motors should be sized according to
short‐term requirements. If they are oversized to cater for potential increase in water demand, then running cost,
as well as capital cost, will be elevated. The pumps and their operation should be well matched to the water
requirements of the process, and it important to maintain pump operation at high efficiencies for the economy of
production.
Page 22
5 5. . T TU UR RB BI IN NE E
TURBINE
5.1 Background
Steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and
converts it to useful mechanical work. In Magnum Ventures Power Plant 2 steam turbines 1
st
is of
4.4MW Extraction cum condensing and 2
nd
is of 2.2MW condensing type. Following is the process
flow diagram
h
1
Figure: Process Flow Diagram for Magnum Ventures Cogeneration Power Plant
5.2 Turbine Efficiency evaluation
Turbine heat rate can be calculated as
Turbine heat rate (Kcal/Kwh) = mass flow rate of Steam(in kg/hr) X (h
1
‐ h
4
)
P(Average power generated in KW)
where
h
1
= enthalpy of inlet steam in kCal/kg
h
2
= enthalpy of extracted steam in kCal/kg
h
3
= enthalpy of steam at condenser in kCal/kg
h
4
= enthalpy of feed water in kCal/kg
Turbine cycle efficiency can be calculated as
Turbine cycle efficiency % = __860 X 100____
Turbine heat rate
Boiler
4.4 Mw Extraction cum
Condensing Turbine
h
2
Extraction at
4kg/cm
2
and 210°C
H
3
G
2.2Mw
Condensing
Turbine
G
Page 23
Table: Monthly average of Steam Supply, Power Generation, Heat rate and Turbine cycle efficiency
M
o
n
t
h
Steam supply to
Turbines
S
t
e
a
m
E
x
t
r
a
c
t
i
o
n
Power Generated
C
o
a
l
C
o
n
s
u
m
p
t
i
o
n
O
v
e
r
a
l
l
p
l
a
n
t
f
u
e
l
r
a
t
e
k
g
/
k
W
h
4
.
5
M
w
T
u
r
b
i
n
e
H
e
a
t
R
a
t
e
(
K
c
a
l
/
K
g
)
2
.
2
M
w
T
u
r
b
i
n
e
H
e
a
t
R
a
t
e
(
K
c
a
l
/
K
g
)
4
.
5
M
w
T
u
r
b
i
n
e
c
y
c
l
e
e
f
f
i
c
i
e
n
c
y
%
2
.
2
M
W
T
u
r
b
i
n
e
c
y
c
l
e
e
f
f
i
c
i
e
n
c
y
%
4
.
5
M
W
2
.
2
M
W
T
o
t
a
l
4
.
5
M
W
2
.
2
M
W
T
o
t
a
l
FEB 679 180 859 472 94179 40071 3759000 227 1.70 4780 2980 18.0% 28.9%
March 654 160 814 448 91259 38222 129481 205 1.59 4753 2772 18.1% 31.0%
April 644 154 798 436 91167 36433 127600 208 1.64 4683 2815 18.4% 30.6%
May 646 164 811 424 92323 38161 130484 160 1.24 4638 2846 18.6% 30.2%
Table: Monthly Fuel Consumption, Steam & Power Production and Supply position
Month FEB March April May
Total Coal Consumption in Ton 6368 6200
6238 4969
Cost of Coal (in Rs.) 2,54,62,199 2,61,71,530
2,57,54,803 2,41,85,169
Total Steam Genration (in Ton) 25,103 25,283 24,994
26,169
Steam supply to Plant (in Ton) 13,236 13,353 13,067
13,141
Total Power Genrated (KWh) 37,59,000 38,54,500
38,28,000 40,45,000
Power Supply to Plant (Kwh) 33,39,000 34,04,000 33,18,000
34,87,000
Fuel Cost per unit of Power (Rs/Kwh)
6.77 6.79 6.73 5.98
Cost of steam (in Rs/ton) 1014.31 1035.14 1030.44 924.19
Aux Power Consumption Kwh 420,000 450,500 510,000
558,000
Aux Power Consumption Ratio % 8.95 8.56 7.51
7.25
Observations:
It was observed that steam generated in the boiler is of specification 65kg/cm
2
and Temperature
445°C against the design temperature of 490°C ±5°C. An increase in inlet steam temperature, i.e., an
increase in superheat at constant inlet pressure and condenser pressure gives a steady improvement
in cycle efficiency and lowers the heat rate due to the increase in inlet temp and rising the inlet
temperature also reduces the wetness of the steam in later section of the turbine and improves
internal efficiency of the turbine.
If the turbine inlet steam temperature is increased to 490°C ±5°C as per the design conditions then
the heat energy input to the turbine will be increased and corresponding effect in cycle efficiency is
achieved as illustrated in following table:
Page 24
Table: illustration of impact of inlet steam temperature on operating conditions and cycle efficiency
Present Case in which
Steam at 65kg/cm
2
and 445 °C
Projected Case
If Steam Temp is 485°C and Pr. 65kg/cm
2
Enthalpy of input steam at 445°C and
65kg/cm2
785.37kcal/kg
Enthalpy of input steam at 485°C and
65kg/cm2 is 808.102kcal/kg
Saturation temp °C 280.86 °C 280.86°C
Enthalpy :@ saturation temperature 664.17 kcal/kg 664.17 kcal/kg
Enthalpy @ outlet conditions : 647 mmhg
vacuum = 113 mmhg pressure absolute
= 620.5 kcal/kg 620.5 kcal/kg
Saturation temperature = 53.5 oC 53.5 oC
Net energy input = steam rate
(kg/hr) *Δ Enthalpy kcal /hr
=35000 * (785.37 –
620.5)
35000 * (808.10 – 620.5)
=5770450 Kcal/hr 6566000 Kcal/hr
Carnot cycle efficiency
= (445 – 53.5) x 100
(445+273)
= 54.53%
= (485 – 53.5) x 100
(485+273)
= 56.93%
Steam Turbines are a major energy consumer. Optimising process operating conditions can
considerably improve turbine water rate, which in turn will significantly reduce energy requirement.
Various operating parameters affect condensing and back pressure turbine steam consumption and
efficiency.
5.3 Effect of Steam inlet pressure
Steam inlet pressure of the turbine also effects the turbine performance. All the turbines are
designed for a specified steam inlet pressure. For obtaining the design efficiency, steam inlet
pressure shall be maintained at design level. Lowering the steam inlet pressure will hampers the
turbine efficiency and steam consumption in the turbine will increase. Similarly at higher steam inlet
pressure energy available to run the turbine will be high, which in turn will reduce the steam
consumption in the turbine. Figure ‐ a & b represents the effects of steam inlet pressure on steam
consumption and turbine efficiency respectively, keeping all other factors constant for the
condensing type turbine.
Fig a: Effect of steam pressure on steam
consumption in condensing type turbine
Fig b: Effect of steam pressure on turbine
efficiency in condensing type turbine
Page 25
Figure ‐ a & b indicates that increase in steam inlet pressure by 1 kg/cm
2
in condensing type turbine
reduces the steam consumption in the turbine by about 0.3 % and improves the turbine efficiency by
about 0.1 % respectively.
In case of back pressure type turbine increase in steam inlet pressure by 1 kg/cm
2
reduces the steam
consumption in the turbine by about 0.7 % and improves the turbine efficiency by about 0.16 % as
shown in figure ‐ c & d. Improvement in back pressure type turbine is more than the condensing
type turbine.
Fig c : Effect of steam pressure on steam
consumption in back pressure type turbine
Fig d: Effect of steam pressure on turbine
efficiency in back pressure type turbine
5.4 Effect of Steam inlet temperature
Enthalpy of steam is a function of temperature and pressure. At lower temperature, enthalpy will be
low, work done by the turbine will be low, turbine efficiency will be low, and hence steam
consumption for the required output will be higher. In other words, at higher steam inlet
temperature, heat extraction by the turbine will be higher and hence for the required output, steam
consumption will reduce. Figure ‐ e & f represents the effects of steam inlet temperature on steam
consumption and turbine efficiency respectively, keeping all other factors constant for the
condensing type turbine.
Fig e:Effect of steam temperature on steam
consumption in condensing type turbine
Fig f: Effect of steam temperature on turbine
efficiency in condensing type turbine
Page 26
Figure ‐ e & f indicates that increase in steam inlet temperature by 10 deg C in condensing type
turbine reduces the steam consumption in the turbine by about 1.1 % and improves the turbine
efficiency by about 0.12 % respectively.
Fig g : Effect of steam temperature on steam
consumption in back pressure type turbine
Fig h: Effect of steam temperature on turbine
efficiency in back pressure type turbine
In case of back pressure type turbine increase in steam inlet temperature by 10 deg C reduces the
steam consumption in the turbine by about 1.5 % and improves the turbine efficiency by about 0.12
% as shown in figure ‐ g &h. Improvement in back pressure type turbine is more than the condensing
type turbine.
5.5 Effect of exhaust pressure/ vacuum
Higher exhaust pressure/ lower vacuum, increases the steam consumption in the turbine, keeping all
other operating parameters constant. Exhaust pressure lower than the specified will reduce the
steam consumption and improves the turbine efficiency. Similarly exhaust vacuum lower than the
specified , will lower the turbine efficiency and reduces the steam consumption. Figure 2a & 2b
represents the effects of exhaust vacuum on steam consumption and turbine efficiency respectively,
keeping all other factors constant for the condensing type turbine. Figure 2a & 2b indicates that
improvement in exhaust vacuum by 10 mm Hg, reduces the steam consumption in the turbine by
about 1.1 %. Improvement in turbine efficiency varies significantly from 0.24 % to 0.4 %.
Fig 2a : Effect of exhaust vacuum on steam
consumption in condensing type turbine
Fig 2b : Effect of exhaust vacuum on turbine
efficiency in condensing type turbine
Page 27
The above figures also demonstrate that considerable in cycle efficiency with decrease of condenser
pressure. Such decrease is mainly depending on the available cooling water temperature and thus
on climatic condition of a place.
Taking the current steam condition and projected steam condition the efficiency gain is projected in
following tables:
Table: impact of steam temperature on 2.2 MW turbine efficiency
Rated Power 2200 kW 2200 kW
HP Steam Pressure 66 bar abs 66 bar abs
HP Steam Temperature 445 °C 485 °C
Exhaust Steam Pressure 0.15 bar abs 0.15 bar abs
Full Load Isentropic Efficiency 76.0 % 80.1 %
Full Load Specific Steam Consumption 4.3 kg/kWh 4.1 kg/kWh
Source: Sugar Engineers Engineering Data software
5.6 Conclusion:
On the basis of above assumptions and theory if the turbine inlet steam temperature is maintained
@ 485°C with keeping all other conditions & factors constant then the projected gain will be:
Table: cost benefit analysis for suggested modification to achieve desired steam temperature
Present average steam demand per day 850 ton per day
Improved steam temperature will reduce steam consumption
by 5.5%, projected steam demand
803 ton per day
Saving in steam for same output 46.75 ton per day
quantity of coal saved due to avoided steam generation 7.8 ton per day
Cost of coal saved 42900 Rs per day
Annual fuel saving 2847 ton
Annual Saving 1,56,58,500
Tentative investment on boiler modification Rs.25,00,000
Simple Payback period 60 days
Page 28
6 6. . C CO ON ND DE EN NS SE ER R C CO OO OL LI IN NG G
6.1 Background
In power plant, the cooling tower, water pumping and condenser are involved
in condensing the exhaust steam from a steam turbine and transferring the
waste heat to the atmosphere.
6.2 Cooling Tower
In the following table specifications of cooling tower are given
Table: Cooling tower specifications
Particulars
Cooling Tower‐1 Cooling Tower‐2
Design Operating Design Operating
Make & Model Paharpur 452‐293 Paharpur 452‐293
Type Induced Draft Cross Flow Induced Draft Cross Flow
No of Cells 3 3 3 3
Rated flow 1200 800 1200 750
Fill Details Treated wood splash bars Treated wood splash bars
No of CT fans 3 3 3 3
CT fan KW 30 15.78/14.35/14.7 30 14.15/11.3/12.1
No. Of blades per fan 9 9 9 9
Dia of Blade assembly 144” 144” 144” 144”
Blade material Cast Al alloy Cast Al alloy Cast Al alloy Cast Al alloy
Hot water inlet temp °C 40 45 40 46.8
Cold water outlet temp °C 32 36.9 32 35
Wet bulb temp. °C 28 26.2 28 25.7
Cooling Tower Performance
Figure: Range and Approach
Page 29
The important parameters, from the point of determining the performance of cooling
towers, are:
Range ‐ is the difference between the cooling tower water inlet and outlet temperature.
Approach ‐ is the difference between the cooling tower outlet cold water temperature and ambient wet
bulb temperature. Although, both range and approach should be monitored, the 'Approach' is a better
indicator of cooling tower performance.
Cooling tower effectiveness (in percentage)‐ is the ratio of range, to the ideal range, i.e., difference
between cooling water inlet temperature and ambient wet bulb temperature.
Cooling capacity ‐ is the heat rejected in kCal/hr or TR, given as product of mass flow rate of water,
specific heat and temperature difference.
Table: Cooling tower operating and efficiency calculations
Parameter
Cooling
Tower‐1
Cooling
Tower‐2
Cooling
Tower‐1
Cooling
Tower‐2
Inlet Cooling Water Temperature °C 45 46.8 44.9 46.1
Outlet Cooling Water Temperature °C 36.9 35 37 34.5
Air Wet Bulb Temperature near Cell °C 26.27 25.7 26.27 25.7
Air Dry Bulb Temperature near Cell °C 38.33 38.8 38.33 38.8
Number of CT Cells on line with water flow 4 4 4 4
Total Measured Cooling Water Flow m3/hr 800 770
CT Range 8.1 11.8 7.9 11.6
CT Approach 10.63 9.3 10.73 8.8
% CT Effectiveness =
43.25% 55.92% 42.40% 56.86% Range ___X 100
(Range + Approach)
Rated % CT Effectiveness (Design Data) 66.66% 66.66% 66.66% 66.66%
Present water quality of makeup water & circulating water for cooling tower at Magnum Ventures,
(Power Plant) Sahibabad are given in following table
Table: Water Chemistry of Cooling Tower make‐up and circulating water
Parameters Makeup water Circulating water
PH 7.0 8.5
P‐ Alkanity Nil 14
M‐ Alkanity 12 70
Chloride 54 504
TDS 102 1217
Total Hardness 8 40
Observations:
¾ Cooling tower ‐1 is having low effectiveness compared to Cooling Tower‐2
¾ CT ‐1 range found to be 7.9 and CT‐2 range found to be 11.6 against design of 8
Page 30
¾ CT‐1&2 approach found to be 10.73 and 8.8 against design 4 indicates, low ambient temp
and poor heat transfer.
¾ CT‐1 &2, effectiveness found to be 42.40% and 56.86% against design 66.66%. which
indicates poor heat transfer in CT
¾ Power measurement indicate under loading on CT fan motors and power factor is in the
range of 0.52 to 0.74. This is poor.
¾ In Cooling Tower ‐1, Fly ash & other foreign particles are presented in reasonable quantity at
most of the places like lowers, frills etc.
¾ Regarding cooling water circulation pumps observations and recommendations are made in
chapter on pumps.
¾ As per the water quality concerned, makeup water quality is very good, here the scaling
chances in the system are very less but corrosion is taking place aggressively specially in MS
pipelines.
¾ At some places in cooling water piping system corrosion observed due to which water
leakage/seepage is existing.
¾ As metal used in the cooling system are MS & Admiral brass so corrosion due to Chloride is
not possible as it attacks only against SS metal, also the Chlorite level in circulating water is
not very high for any trouble, with such metals (MS &AB) system may be run upto 2000ppm
chloride level in the circulating water.
¾ Water in contact with metal surface sets up an electrolytic cell where by metal undergoes
slow but steady dissolution. The metal is constantly oxidized to the metal oxide in presence
of water with its dissolved oxygen, unless controlled properly.
¾ The corrosion in the system is due to improper functioning of corrosion inhibitor treatment.
As PH in circulating water is around 8.5, Zn as corrosion inhibitor will not work perfectly at
higher PH. As Zinc will precipitate at higher PH & not inhibit the surfaces perfectly. So
organic treatment will be a good option for corrosion control.
¾ Alkalinity in the makeup water is very less; treatment philosophy must be designed to take
care of low alkalinity system to control corrosion.
6.4 Conclusion and recommendation:‐
¾ For energy savings and better air flow consider replacement of Aluminium alloy cooling
tower fan blades, with energy efficient FRP hollow fan blade. Refer table below for detail
cost benefit analysis.
¾ Cooling tower fills needs to be checked for fill chocking and poor water distribution. Equal
and uniform water flow to each cell to be ensured for proper distribution of water. This will
improve effectiveness of CT. Improved CT performance will allow to stop one CT fan during
cold weather conditions.
¾ Periodically clean plugged cooling tower nozzle
¾ Monitor approach, effectiveness and cooling capacity for continuous optimisation efforts, as
per seasonal variations as well as load side variations.
¾ A good chemical treatment with proper monitoring of the system will overcome all the
water related problems in the system.
¾ Corrosion rack must be installed on monthly basis to check corrosion rate (mpy) in the
system.
¾ Also Fly ash & other foreign particles adding microbiological load to the cooling system , a
side stream filter may be installed to remove suspended particles from cooling towers along
Page 31
with proper bio‐dispersant dosing & Chlorine Di‐Oxide treatment in place of using
oxidizing/non oxidizing biocide.
Table: Cost benefit analysis with proposed modification of cooling tower fans blade material
Parameters Present Fan
System
Proposed Cooling Tower Fan System
Case‐1
With New Motor
Case ‐2
With existing motor
Fan Specifications
No. of Fans 3
Replace Fan blade by EE
FRP hollow fan Blades &
EE Motors of proper rating
Replace Fan blade by EE
FRP hollow fan Blades only
and utilise existing motors
No. of Blades per fan 9 8 8
Dia of Blade assembly 144” 144” 144’
Blade Material Cast Al alloy FRP hollow fan Blades FRP hollow fan Blades
CT Fan Motor KW 30Kw 15 30
Required Motor 30KW 15 KW 15 KW
Energy Consumption 18 Kw
12 KW at 80% loading and
95% efficiency motor
With present motor
efficiency projected motor
load ‐ 15 KW
Energy consumption per
day
432KWh 288Kwh 360 Kwh
Annual Energy Saving Nil 52560 Kwh 26280 Kwh
Saving in recurring
Energy cost per annum
(@Rs5/Kwh)
Nil 2,62,800 INR 1,31,400 INR
Cost of New blade set
For each set of
blades
85,000/‐ INR for each set
Simple pay back
For each set of
blades
4 months (118Days) 8 months (236Days)
The payback period through saving of recurring energy cost and consumption reduction by new FRP
hollow CT fan blades, for each set of fan blades replaced is 4months when FRP Hollow Fan blades are
installed with new high efficiency motor and 8 months if only new set of FRP Hollow Fan blades are
installed with existing motor.
Page 32
7 7. . E EL LE EC CT TR RI IC CA AL L S SY YS ST TE EM M & & M MO OT TO OR RS S
7.1 Background
Different types of electrical motors are used in a power plant to drive the various equipments like:
¾ Pumps
¾ Fans
¾ Blowers
¾ Coal handling equipments
¾ Crushers
¾ Others
These motors and connected equipments consume significant amount of energy, which contributes
to auxiliary power consumption.
The auxiliary power consumption of this plant varies from 7.25% to 9% during the different months.
Electrical system and Motors
7.2 TRANSFORMERS
The facility is having two transformer which are installed to step down the 6.6 KV voltage supply
generated by 4.4 MW transformer.
The transformers at Magnum Ventures Limited are naturally oil cooled. They are provided with
Manual Off‐load Load Tap Changer. The 2000 KVA transformer is plinth mounted and 6500 KVA
transformer is mounted at height.
OBSERVATION
1. There is no sub metering of the transformers.
2. The cumulative transformation capacity is 8500 KVA for 4300 MW (5625 KVA) Alternator.
3. The earthing pits are not adequately spaced.
Page 33
RECOMMENDATION
1. There is no sub metering of the transformers. It is highly recommended to install a sub
meter on each of the transformer for monitoring the loading of the transformer.
2. The earthing pits provided are also not adequately spaced. This causes the earthing currents
to either keep circulating in the system or is injected into the ground at various stages thus
increasing heat losses. Due to this a major amount of energy which is produced is not
recorded in the meters and a low efficiency is recorded.
3. The proper earthing also enhances the protection relays to function as per the design
parameters and will improve system safety and reliability.
7.3 POWER FACTOR ANALYSIS
The primary purpose of the capacitor is to reduce the maximum demand. The additional benefits
can be derived by capacitor location. Maximum benefit of capacitor is derived by locating them close
to the load. In this way the KVAr are confined to the smallest possible segment, decreasing the load
current. This reduces the power losses of the system substantially.
The overall power factor of the plant is being maintained at above 0.93 lagging, but the power
factor of some of the individual feeders is below the satisfactory level as given in the following bar
chart.
OBSERVATION
1. The installed power factor compensating capacitors through ensures an overall good PF,
since they are concentrated in few panels therefore the lagging currents are circulated in the
whole distribution and transmission system.
Transmission losses of plant are the losses occurring in main transformers, H.T. Cables,
Switch Gear etc. = 3 % (Of total yearly Consumption). Distribution losses of plant are the
losses occurring in main L.T. Cables, L.T. Switch Gear, L.T. Bus ‐Bar etc. = 7 % (Of total yearly
Consumption)
Page 34
The following feeders were monitored using 3 phase power analyzer and the tentative
savings at Rs. 3 per unit has been calculated for the purpose of payback period.
Table: Annual Monetary Losses due to plant Distribution and Transmission Losses
Annual Monetary Losses due to plant Distribution and
Transmission Losses
Units generated at 0.8 PFL and availability Units
4400 KW Generator 24107520
2200 KW Generator 12334080
Total units generated in KWH 36441600
Plant distribution losses and transmission
losses (3%) in KWH 728832
Losses in monetary terms at Rs. 5/ unit 3644160
RECOMMENDATION
1. The installed capacitors need to be tested and relocated so that the plant transmission and
distribution losses are reduced. The expected annual savings are Rs. 36, 44,160.
Table: Capacitors installation Pay Back Period Calculations
Si mpl e Pay Back Peri od Cal cul ati ons
Total l oad of the f eeders 1358. 5 KW
Average PF of the i ndi vi dual f eeders 0. 75 l aggi ng
I mproved PF 0. 95 l aggi ng
KVAr requi red 749. 892 KVAr
I nvestment needed Rs. 3, 59, 948. 16
Si mpl e Pay Back 1. 2 months
7.4 LOADING PATTERNS OF MOTORS
The motors are desi gned to run at maxi mum ef f i ci ency when they are l oaded more
than 60%. The power f actor of the motors al so decreases drasti cal l y when the
motor i s under l oaded. Si mi l arl y, i n the over l oaded condi ti on the effi ci ency,
power factor, heati ng i . e. overal l performance of the motor decreases. Therefore,
i t becomes one of the vari ous cri teri ons to eval uate the motor perf ormance. Thi s
not onl y hel ps i mprovi ng the ef f i ci ency as wel l as takes hel ps i n the ri ght sel ecti on
of the motor capaci ty.
The l oadi ng pattern of the pl ant motors i s gi ven i n fol l owi ng tabl e.
Page 35
Tabl e: Loadi ng pattern of pl ant motors
OBSERVATI ON
1. The fol l owi ng motors are operati ng at l ess than 60% l oadi ng. I D Fan motor
l oadi ng i s bei ng opti mi zed wi th the hel p of VFD.
Tabl e: Li st of motors operati ng at l ess than 60% l oadi ng
Page 36
RECOMMENDATION
1. The f ol l owi ng motors are recommended to be changed wi th the l ower
capaci ty and ef f i ci ent motors.
Tabl e: Li st of motors recommended for repl acement wi th the l ower capaci ty
and energy effi ci ent motors.
The Pay Back peri od of the motors has been i ncl uded i n the motor ef f i ci ency
secti on of the report.
7.5 MOTOR EFFICIENCY
There are 48 motors in the power plant of capacity more than 3.5 HP. In all the operating
parameters of 25 motors were successfully measured. There efficiency was calculated with the help
of the measured and design data. The results are presented in the following table.
Motor Efficiency Calculation
Page 37
Table: Power Plant Motor efficiency
RECOMMENDTIONS
After calculating the efficiency and monitoring the motor loading, the following motor have been
suggested to be replaced with optimum capacity efficient motors. The annual savings in KWH and
monetary terms has been calculated to determine the pay back period of each of the motor.
Page 38
Table: Techno economic analysis for replacement suggested motors
The total investment to replace the above mentioned motors is Rs. 6, 77,700
The cumulative annual saving in energy is 681959 KWH
The cumulative monetary saving is Rs. 34, 09,797
The cumulative simple pay back period is 3 months
7.6 HARMONIC ANALYSIS
We have measured Harmonic Level in the plant and results are mentioned as under.
Table: Harmonic Measurement of Main Feeders
Page 39
OBSERVATION
1. The average total vol tage harmoni c di storti on i s 6. 45%.
2. The average total current harmoni c di storti on i s 9. 3%.
Tabl e: Harmoni cs Measurement of Motors
Sno. Description of Motor
Voltage Harmonics Current Harmonics
3
rd
5
th
7
th
THD 3
rd
5
th
7
th
THD
1 FD Fan 0 22.4 7.7 8.6 21.8 72.9 27.7 52.6
2 ID Fan 0 22.5 6.1 6.5 4.8 22.5 11.4 47.7
3 Boiler FP 1 0 20.9 7.4 6.2 18.1 69 22.5 9.6
4 Boiler FP 2 0 19.7 4.6 5.3 5.2 21.1 6.5 9.7
5 Coal crusher 1 0 15.3 6.1 3.8 0.3 1.6 0.8 8.3
6 Coal crusher 2 0 14.7 6 5 0 2.2 0.5 9.9
7 Main elevator 1 0 15 1.2 5.3 0 0.9 0.3 9.5
8 Main elevator 2 0 5.3 1.2 5.6 1.1 9.5 2.1 10.8
9 Belt conveyor 0.5 14.2 4.1 20 4.1 9.7 3.1 13.2
10 Reject elevator 1 0 22 7 5.9 22 30 15.5 45
11 Reject elevator 2
12 Submersible pump 1 0 23.1 6.3 5.6 0.3 1.5 0.3 3.8
13 Submersible pump 2 0 8.3 4.8 2.6 0.5 0.7 1.2 3.7
14 Submersible pump 3 0 25.1 11.6 7.6 0.7 3.7 1.4 10.4
15 Ash handling motor 0 19.7 7.5 6.4 0.4 0.8 0.4 12.6
16 PA Fan 0 18.8 7 6.1 6.7 16.7 6.1 43
17 HP 2‐1 RO 0 16.3 6.1 4.5 0.3 1.9 0.6 8.2
18 HP 1‐1 RO 0 15.8 5.3 4.3 0.3 1.8 0.4 7.2
19 HP 1‐2 RO 0 16.8 7.2 4.3 0.4 1.6 0.6 8.5
20 HP 2‐2 RO 0 14 6.1 4.1 0.3 1 0.5 7.5
21 Top screw 1 0 5 1.4 5.7 2.2 12.4 2.2 16
29 2.2 MW CT Pump 1 0 5.4 0 1.3 0 0.4 0.3 1.2
30 2.2 MW CT Pump 2 0 5.2 0 1.5 0.3 0.5 0.4 2.6
31 2.2 MW CT Pump 3
32 2.2 MW CT Fan 1 0 5.2 3.1 1.5 0.4 0.8 0.4 3.9
33 2.2 MW CT Fan 2 0 4.7 0 1.4 0 0.8 8.4 3.6
34 2.2 MW CT Fan 3 0 4.6 3.1 1.4 0.4 0.6 0.4 3.8
35 2.2 MW CEP 1 0 4.5 0 1.4 0 0.5 0.3 2.9
38 4.4 MW CT Fan 1 0 20.1 5.7 5.3 0.8 3.5 1.3 14.8
39 4.4 MW CT Fan 2 0 18.1 5.5 4.8 1.5 3.2 0.6 13.4
40 4.4 MW CT Fan 3 0 15.6 7 4 0.8 2.9 1.5 10.8
OBSERVATION
1. The average total vol tage harmoni c di storti on i s 5. 34%.
2. The average total current harmoni c di storti on i s 13. 59%.
Page 40
7.7 POWER SUPPLY QUALITY
The BI S standard speci f i es that a motor shoul d be capabl e of del i veri ng i ts rated
output wi th a vol tage vari ati on of 6%. The conti nuous vol tage vari ati on causes
motors to heat up and thus tri ggeri ng the deteri orati on of i nsul ati on system. The
Power Factor, Sl i p and torque of the motor i s al so aff ected by the vol tage
vari ati on.
Tabl e: Power suppl y qual i ty and Vol tage Vari ati on
OBSERVATION
1. The vari ati on between the termi nal vol tage and speci fi ed vol tage i s under
5% whi ch i s a heal thy si gn.
REF - JCTE/09-10/29791 Dated : 26-06-2010
M/s Modinagar Paper Mills ltd.
Modinagar
U.P
Sub : Quotation for FRP Fan Assembely for Cooling Tower.
Kind Atten : Mr.Anubhav Gupta
Dear Sir,
We are receipt of your enquiry No –nil Dated :26-06-10 regarding requirement of FRP Fan
Assembly for cooling tower . Now we are quoting our best.
SI. NO. DESCRIPTION OF ITEM QTY UNIT RATE AMOUNT
01. FRP HOLLOW FAN BLADES
COMPLETE WITH HUB .
(Statically Balanced) 1Set 85,000/- 85,000.00
of 8blades
No. Of Blades -8
MOC of Blades – FRP Hollow type
TERMS & CONDITIONS :
Delivery : With in 2-3 Weeks after receipt of your P.O.
Payment : 40% Payment along with P.O. and balance payment on submission of P.I Prior to
dispatch.
Sales Tax : 2% against form "c"
Valadity : 30 Days.
Packing & Forwarding Charges : Nil
Freight Charges : Extra At Actual.
Insurrance : By Customer.
Guarantee : 1 year from the date of supply.
Thanking You
Your"s Faithfully
For JITENDRA COOLING TOWER (ENGS)
Authorised Signatuory (J.D.Sharma)
cell-9313784391
‐ 1 ‐
APPENDIX 1
What is Harmonics:-
At the time of the designing any A.C. machine, it is assumed that voltage and current wave from
at the output terminals of A. C. machines is assumed to be sinusoidal and consists of only one
frequency which is called fundamental frequency or 1
st
harmonics and such sinusoidal wave
from dose not contain harmonics of other frequency.
Due to non linear system load such as thyristorised control, variable frequency drive and D. C.
motor, a harmonics are generated at the output side of the A.C. machines and hence original
sinusoidal wave form are disturbed and wave form becomes complex and non sinusoidal in
nature generating 2nd, 3rd, 4th and so on frequencies of the fundamental frequency.
The above phenomenon is shown in the below given diagram.
These 2
nd
, 3
rd
, 4
th
frequencies are called harmonics of the fundamental frequency. In short
waveform with frequencies other than fundamental frequency is called harmonics.
2
nd
, 4th etc frequencies are called even harmonics and 3
rd
, 5
th
, 7
th
, etc frequencies are called
harmonics.
Harmonics in transformer:-
The non‐sinusoidal nature of the magnetizing current necessary to produce a sine wave of flux
produces harmonics in current and voltage wave –forms of the three phase transformers.
The effects of current harmonics:‐
1. Increased heating of winding.
2. Inductive interference with communication circuits.
3. Increased iron losses.
The effects of voltage harmonics:-
a) Increased heating of winding.
b). Capacitive interference with communication circuits.
c). Production of large resonant voltages.
Maj or Causes of Harmoni cs
Devi ces that draw non‐si nusoi dal currents when a si nusoi dal vol tage i s appl i ed
create harmoni cs. Some of these devi ces are l i sted bel ow:
El ectroni c Swi tchi ng Power Converters
1. Computers, UPS, Sol i d‐state recti fi ers.
2. El ectroni c process control equi pments
3. El ectroni c Li ghtni ng Bal l asts.
‐ 2 ‐
4. Reduced vol tage motor control l ers.
Arci ng Devi ces
1. Di scharge l i ghti ng.
2. Arc furnaces, wel di ng equi pments.
Ferromagneti c devi ces.
1. Transformers operati ng near saturati on l evel .
2. Magneti c bal l asts.
3. I nducti on heati ng equi pment chokes.
Appl i ances
1. TV sets ai r condi ti oners, washi ng machi nes, and mi crowave ovens.
2. Fax machi nes, photocopi ers, and pri nters.
Hi gher RMS current and vol tage i n the system are caused by harmoni c
currents, whi ch can resul t i n any of the probl ems l i sted bel ow:
1. Bl i nki ng of I ncandescent Li ghts‐ Transformer Saturati on.
2. Capaci tor Fai l ure‐ Harmoni c Resonance.
3. Ci rcui t Breakers Tri ppi ng‐ I nducti ve Heati ng and Overl oad.
4. El ectroni c Equi pment Shutti ng down‐ Vol tage Di storti on.
5. Fl i ckeri ng of Fl uorescent l i ghts‐ Transformer Saturati on.
6. Fuses Bl owi ng for no apparent reason‐ I nducti ve heati ng and Overl oad.
7. Motor Fai l ures (overheati ng) – Vol tage Drop.
8. Conductor Fai l ure‐ I nducti ve heati ng.
9. Neutral conductor and termi nal fai l ures – Addi ti ve Tri pl en currents.
10. El ectromagneti c Load Fai l ures – I nducti ve heati ng.
11. Overheati ng of Metal Encl osures‐ I nducti ve heati ng.
12. Power I nterference on voi ce communi cati on‐ harmoni c noi se.
13. Transformer fai l ures‐ I nducti ve Heati ng.
Overcomi ng Harmonics
Tuned Harmoni cs fi l ters consi sti ng of a capaci tor bank and reactor i n seri es are
desi gned and adopted for suppressi ng harmoni cs by provi di ng l ow i mpedance
path for harmoni c component. The harmoni c fi l ters connected sui tabl y near the
equi pment generati ng harmoni cs hel p to reduce THD to acceptabl e l i mi ts. For
overcomi ng and troubl eshooti ng of some probl ems i n the el ectri cal power
system
‐ 3 ‐
HARMONICS WAVE FORM
‐ 4 ‐
APPENDIX 2
Power factor improvement with the use of static capacitors:‐
In case of alternating current power supply system current is always lag behind the voltage. This
is due to the fact that the A.C. machines works on the principle of electromagnetic induction
and these A.C. machines consume reactive power for their own needs for formation of
magnetic flux and this phenomenon will cause current vector to lag behind the voltage vector
and this will generates the P.F. in the system. The above fact is shown in below sine wave
diagram.
What is Power Factor:‐
The P. F. = CosØ is the ratio of KW = Active Power
KVA Apparent Power
Methods of improving power factor:-
1. With the use of static capacitors.
2. With the help of synchronous condenser.
3. With use of phase advancers.
‐ 5 ‐
Here we can discuss the use of static capacitor and there advantages for improving
How Power factor improves with the use of static capacitors:‐
The static capacitor generates reactive current of opposite nature at leading power factor when
connected to the supply mains parallel to inductive load and compensates reactive current of
the inductive load, which is running at lagging power factor.
∴ When static capacitor is connected parallel to the inductive load, the inductive load starts
receiving reactive power of opposite nature at leading power factor from the capacitors and
thus this reactive power neutralizes the inductive power requirement of the load and thereby
improves the P. F. of the load.
The above Explanations are made simple with the below mentioned Vector Diagram.
The P. F. = Cos0 is the iatio of KW = Active Powei
KvA Appaient Powei
Vector diagram and physical diagram of inductive load with use of capacitor
‐ 6 ‐
Effect of Different Power Factor on 100 KW Industrial Motor Working Load:
Assume 3 phase, 100 KW rating inductive motor., V = 415, P.F. = Cos ↓ = Cos 0° = 1,
∴↓ = 0°,
F = 50 HZ, Efficiency = 90 % Sin ↓ = Sin 0° = 0
η 0f Notoi = 0utput Input = 1.7S x v x I x Cos ↓ = output x 1uu
Input η
I = 1uu x1uuu
1,7S x 41S x1 x u.9u
I (line) = 1SS Amp.
Active Cuiient = I active = I(line) x Cos ↓ = 1SS x 1 = 1SS Amp.
Reactive Cuiient = I ieactive = I(line) x Sin ↓ = 1SS x u = u Amp.
The KvA = KW = 1uu =1uu KvA
Cos ↓ 1
KW = KvA x Cos ↓ = 1uux1 = 1uu
‐ 7 ‐
KvAi = KvA x Sin ↓ = 1uuxu = u
Vector Diagram
Active Powei – (KW) = 1uu
Reactive powei‐(KvAi) = u
Appaient oi iesultant powei – (KvA) = 1uu
(B) 100 KW load working at Cos ↓ = P. F. =0.90, ∴↓ = 25°
The KVA = KW = 100 = 111 KVA
Cos ↓ 0.90
Line Cuiient = I (line) at P.F of u.9u = 1SS Amp.¡ u.9u = 172 Amp
Active Cuiient = I active = I(line) x Cos ↓ = 172 x u.9u = 1SS Amp
Reactive Cuiient = I ieactive = I(line) x Sin ↓ = 1SS x u.422 = 64.4 Amp.
KW = KvA x Cos ↓ = 111xu.9u = 1uu
KvA = 111
KvAi = KvA x Sin ↓ = 111xu.422 = 47
: Vector Diagram :
Active powei – (KW) = 1uu KW
↓ = 2S° voltage vectoi ‐ v
Cuiient vectoi – A . Reactive powei–(KvAi) = 47
Appaient oi iesultant powei – (KvA) = 111
(C) 100 KW load working at Cos ↓ = P. F. = 0.80, ∴↓ = 36.8°
Line Cuiient = I (line) at P.F of u.9u = 1SS Amp.¡ u.8u = 194 Amp
Active Cuiient = I active = I(line) x Cos ↓ = 194 x u.8u = 1SS Amp
‐ 8 ‐
Reactive Cuiient = I ieactive = I(line) x Sin ↓ = 194 x u.S99 = 116 Amp
The KvA = KW = 1uu = 12S KvA
Cos ↓ u.8u
KW = KvA x Cos ↓ = 12Sxu.8u = 1uu
KvA = 12S
KvAi = KvA x Sin ↓ = 12Sxu.S99 = 7S
: Vector Diagram :
Active powei – (KW) = 1uu KW
↓ = S6.8°
voltage vectoi ‐ v
Reactive powei–(KvAi) = 7S
Cuiient vectoi ‐ A
Appaient iesultant powei – (KvA) = 12S
Fiom the above vectoi uiagiams anu below mentioneu calculation it can be
seen that at
(A) 1uu KW loau anu P. F. = 1 ∴KvA = 1uu KvA
∴ Bemanu chaiges = 1uu x Rs.2uu = Rs.2uuuu¡‐
(Assuming Bemanu Chaiges = Rs. 2uu ¡KvA)
(B) 1uu KW loau anu P. F. = u.9u ∴KvA = 111 KvA
∴ uemanu chaiges = 111 x Rs. 2uu = Rs.222uu¡‐
‐ 9 ‐
APPENDIX 2A
Methods of testing & checking of capacitors:‐
• With the help of AVO meter ‐ A good capacitor will show dead short between
any two terminals first & then charge up to battery voltage.
• Megger test‐ A good capacitor will show infinity resistance between any
terminals & earth.
• With the help of Ampere meter ‐ A good capacitor will draw rated current at
rated voltage.
We suggest checking the APFC capacitor current ratings, every week and replacing any
faulty capacitors as soon as possible.
Importance of good Power Factor and various benefits thereof: ‐
1. The KW capacity of the prime movers is better utilized.
2. The KVA capacity of the transformers and cables are increased.
3. The efficiency of every plant is increased.
4. The overall production cost per unit decreased.
5. Heat losses in any electrical machine = k x 1/P.F. and hence high P. F. will generate less
heat.
6. Reduction of plant electrical losses due to improvement of P. F. = 1 -
0Id PP
2
Ncw PP
2
7. KVA reduction =Im x |
1
PP 1
-
1
PP 2
|
Disadvantages of poor power factor: ‐
1. Losses in any electrical equipment are proportional to i² which means proportional to
1/P.F.² thus losses at P.F. = Unity = 1 and losses at P.F. = 0.8 are 1/ [0.8] ² = 1.57 times
higher than those at unity P. F.
‐ 10 ‐
2. Rating of motors and transformers etc. are proportional to current hence to 1/P. F.
therefore large motors and transformers are required.
3. Poor P. F. causes a large voltage drop, hence extra regulation equipment is required to
keep voltage drop within prescribed limits.
Indirect benefits of improved P. F.:- (Example for understanding)
1. Losses reduction of the plant due to improvement in P. F. from P. F. 1 (0.92) to P. F. 2
(0.98)
Now we are raising the existing P. F. of 0.92 to new P. F. of 0.98.
Therefore, monthly energy loss reduction in the plant, due to improvement of PF
= 1 -
PP 1
2
PP 2
2
= 1 -
0.92
2
0.98
2
= 1 – 0.8812
= 0.1188
= 11.88 %
When current I amperes flow through any electrical machines having resistances R ohms for t
seconds the electrical energy expended is I² x R x t joules.
∴Heat produced = I² x R x t / 4187 kilocalories.
∴Heat produced at PF 1 (0.92) = k [1/ (PF 1)
2
] & Heat produced at PF 2 (0.98) = k [1/(PF 2)
2
]
∴Reduction in heat generation due to improvement of P. F.
= k x |
1
PP 1
2
-
1
PP 2
2
|
= k x [ 1.1814 – 1.0412 ]
= k x 0.1402 Calories
‐ 11 ‐
APPENDIX 3
Motor Efficiency Test (No Load Method)
We have taken measurement 10 HP motor for calculation of efficiency.
Motor Specifications
Rated power = 7.5 kW/10 HP
Voltage = 415 Volt
Current = 17 Amps
Speed = 935 RPM
Connection = Delta
No load test Data
Voltage, V = 424 Volts
Current, I = 5.9 Amps
Frequency, F = 50 Hz
Stator phase resistance at 20 °C = 2.5 Ohms
No load power, P
nl
= 156 Watts
( a) Let Iron Plus Friction and windage Loss , Pi + fw
No load Power P
nl
– 156 Watt
Stator copper Loss, P
st
@ 20
o
C (P
st.Cu
)
= 3 x (5.9/1.73)
2
x 2.5
= 87.23 Watt
Now Pi + fw = Pnl – Pst.cu = 156 – 87.23 = 68.77 Watt
(b) Stator Resistance at 120
C
R
120
= 2.S x
120+235
20 + 235
= S.48 0bms
(c) Stator Copper Losses at Full Load P
st.cu
120
0
C
= 3 x (17/1.73)
2
x 3.48
= 1008.32 Watt
‐ 12 ‐
(d) Full Load Slip =
P
Out
(1-S)
=
(1000-935)
1000
= 0.065
Thus, Input to Rotor =
P
Out
(1-S)
=
7500
(1-0.065
=
7500
0.935
= 8021.40
(e) Total Full Load Input Power
= 8021.40 + 1008.32 + 68.77 + 37.5 ( stray Losses 5 % of rated Output)
= 9135.99 Watt Say 9136 watt
(E) Motor efficiency at Full Load =
P
Output
P
Input
x 1ûû
= 82.09 % say 82 %
Above test clearly shows that Old and many times rewind Motors have very low
efficiency as compared to new Energy efficient Motor. New Energy Efficient
Motors have efficiency up to 95%.
So you are advised to avoid the use of old rewound motors or motor with stated
efficiency of less than 90% on test certificate in future.
Above motors have total measured running load as 463.75 KW and average
efficiency of 83.6%.
Replacement of motors can bring the efficiency of 95% on running load thus
improving efficiency by 11.4% and subsequently reducing the load by 52.86 KW.
This will result in savings of 52.86 x 20 hrs per day x 30 days = 31716 KWH each
month = 31716 x 4.19 = INR 1,32,890 each month
Tentat
Salvag
Thus n
Hence
We re
motor
: Pow
tive invest
ge Value of
net investm
simple pa
commend
s and mai
wer Stag
tment of 4
f old moto
ment = 11
ayback = 9
d use of B
ntain very
ges In An
410.88 KW
ors = 400 x
109382 – 1
924182/13
aldor mot
y high effi
n Induct
W = 410.88
x 463 KW
185200 = I
32890 = 6
tors which
ciency eve
tion Mo
8 x 2700 p
= INR, 1,8
INR 9,24,1
.95 say 7
h are NEM
en at 25%
tor:
er KW = IN
85,200
182
Months.
MA Premiu
loading.
NR 11,09,
um efficie
‐ 13 ‐
382
ncy range
‐
e
‐ 14 ‐
Variation of Motor Efficiency /P. F / Stator Current / Torque & Speed
with receipt to Load Demand
Power Loss Due to Under Load Operation of Induction Motor
(% of Power Loss in Motor):
Whenevei inuuction motois iuns in unuei loau conuitions, heavy powei
losses aie obseiveu anu hence unuei loauing anu no loau iunning of the
inuuctions motoi aie to be avoiueu.
Foi oui customeis knowleuge a following chait of powei losses is attacheu.
Power Loss Due to Under Load Operation of Induction Motor
(% of Power Loss in Motor) :
Notoi Capacity in
B.P.
No Loau 2S % Loau Su % Loau Full Loau
S Su 4u 2S 18
7.S 4S Su 2u 17
1u 44 26 18 17
1S 4S 2S 17 14
2u 42 2u 1S 14
2S 41.S 19 1S 1S
Su 41 18 14 1S
4u 4u 17 1S.S 1u.S
Su 4u 16 12.S 1u
6u S9 1S.S 12.S 1u
7S S8.S 1S 12 9
1uu S8 1S 12 9
Motor Rati ng
(HP)
Capaci tor rati ng (kVAr) f or Motor Speed
3000 1500 1000 750 600 Suu
S 2 2 2 3 3 S
7. S 2 2 3 3 4 4
1u 3 3 4 5 5 6
1S 3 4 5 7 7 7
2u 5 6 7 8 9 1u
2S 6 7 8 9 9 12
Su 7 8 9 10 10 1S
4u 9 10 12 15 16 2u
‐ 15 ‐
Su 10 12 15 18 20 22
6u 12 14 15 20 22 2S
7S 15 16 20 22 25 Su
1uu 20 22 25 26 32 SS
12S 25 26 30 32 35 4u
1Su 30 32 35 40 45 Su
2uu 40 45 45 50 55 6u
2Su 4S Su Su 6u 6S 7u
Table – Rating of Capacitor required for different rating and
speed.
‐ 16 ‐
‐ 17 ‐
APPENDIX 4
Peifoimance Evaluation of Notois
Electrical motors accounts for a major part of the total electrical consumption. So
a careful attention should be given to the performance of this utility.
Measurements of the different electrical parameters of the major motors of the
plant are given in Table
The efficiency of the induction motor and loading condition of the motors are
directly proportional to each other. Higher the loading and higher is the efficiency
of the motors. The best efficiency of the motors is achieved at a load very much
near to the rated load.
Moreover at lower loads the power factor is on the lower side increasing the load
current and thereby increasing the copper losses, resulting in lower efficiency, the
rating of the motors should be decided after carefully understanding the process
requirement in the absence of which the motor might come out to be oversized.
Also one should run a motor, which has been rewound more than once as every
time a motor is rewinded it losses 2 – 5% of its actual efficiency.
Motor performance is affected considerably by the quality of input power that is
the actual volts and frequency available at motor terminals, vis‐à‐vis rated values
as well as voltage and frequency variations and voltage unbalance across the
three phases.
Mostly all the motors are old or rewound at least once. A good saving can be
achieved if higher efficient ones replace them. Though it’s a scheme with higher
initial investment but can be implemented phase wise. Induction motors are
characterized by power factors less than unity, leading to lower overall efficiency
(and higher overall operating cost) associated with a plant’s electrical system.
Capacitors connected in parallel (shunted) with the motor are typically used to
improve the power factor. The impacts of PF correction include reduced KVA
demand (and hence reduced utility demand charges), reduced I
2
R losses in cables
‐ 18 ‐
(leading to improved voltage regulation), and an increase in the overall efficiency
of the plant electrical system.
It should be noted that PF capacitor improves power factor from the point of
installation back to the generating side. It means that, if a PF capacitor is installed
at the starter terminals of the motor, it won’t improve the operating PF of the
motor, but the PF from starter terminals to the power generating side will
improve, i.e., the benefits of PF would be only on upstream side.
The size of capacitor required for a particular motor depends upon the no‐load
reactive KVA (KVAR) drawn by the motor, which can be determined only from no‐
load testing of the motor. Higher capacitors could result in over‐voltages and
motor burnouts. Alternatively, typical power factors of standard motors can
provide the basis for conservative estimates of capacitor ratings to use for
different size motors.
‐ 19 ‐
APPENDIX 4A
We are suggesting some Measures to Improve Efficiency of Motors and
Distribution system
1: Electrical Distribution Correction
Measures available to improve power quality and reduce electrical losses are
1. Maintain voltage level close to nameplate level as far as possible, with a
maximum deviation of 5% (at 5% under voltage, copper loss is increased to
10%).
2. Minimize phase imbalance within a tolerance of 1%. As deviation of one
phase voltage from average phase voltage increases, it will result in
increased winding temperature.
3. Maintain high power factor to reduce distribution losses.
4. Avoid excessive harmonic content in the power supply system, as increased
harmonic content in power supply system will increase motor temperature.
5. Use oversize distribution cable in the new installation to reduce copper
losses. This will also help in reducing voltage drop during starting and
running and minimizing the motor losses.
2: Motor Efficiency Improvement
The measures available to improve motor efficiency are:
1. If motor is running at partial load then convert motor from delta to star
connection. This will improve motor efficiency.
2. Replace rewound induction motor (with reduced efficiency) with new
energy efficient motor.
3. If process demands oversized motor then possibility of use of VFD may be
explored to save energy. This is also applicable in case of varying load duty
cycle motor application.
4. Control the motor drive temperature. This will reduce copper losses and
increase motor life.
‐ 20 ‐
3: Better System Matching
Measures available are:
1. Use an on/off control system using timer, PLCs, etc to provide motor power
only when required.
2. Size the motor to avoid insufficient low load operation. Motor should run at
65% to 95% of its nameplate rating to get maximum efficiency.
4: Driven Load and Process Optimization
Measures available to optimize the process and its operation are:
1. Change or reconfigure the process or application so that less input power is
required.
2. Downsize the over sized pumps, fans, compressors or other driven loads if
possible.
3. Install more efficient mechanical subsystems. Check that coupling, gearbox
fan or pump must be energy efficient.
Miscellaneous Measures to Improve Motor Efficiency
Maintenance Energy savings of 10 to 15 percent of motor energy consumption
can typically be realized, depending on change from existing maintenance
practices.
These are:
1. Proper lubrication: it will minimize wear on moving parts. Lubrication is best
done on a regular schedule to ensure wear is avoided. Once it occurs, no
lubricant can undo it. It is crucial that the correct lubricant is applied in the
right quantities.
2. Correct shaft alignment: It ensures smooth, efficient transmission of power
from the motor to the load. Incorrect alignment puts strain on bearings and
shafts, shortening their lives and reducing system efficiency. Shafts should
be parallel and directly in line with each other. It is necessary to use
precision instruments to achieve this. Shaft alignment is an important part
of installation and should be checked at regular intervals.
3. Proper alignment: Belts and pulleys must be properly aligned and tensioned
when they are installed, and regularly inspected to ensure alignment and
‐ 21 ‐
tension stay within tolerances. Abnormal wear patterns on belts indicate
specific problems that may require correction. Loose bests may squeal and
will slip on the pulleys, generating heat. Correctly tensioned pulleys run
cool. Excess tension strains bearings and shafts, shortening their lives.
4. Painting of motor: Avoid painting motor housing because paint acts as
insulation, increasing operating temperatures and shortening the lives of
motors. One coat of paint has little effect, but paint buildup accumulated
over years may have a significant effect.
‐ 22 ‐
APPENDIX 5
Maintenance Schedule of MOTOR for Energy Conservation
i). Daily: ‐
Clean the motor and starter.
ii). Weekly: ‐
Clean slip rings with soft brush dipped in white spirit.
iii). Monthly: ‐
Check earth connections of motor and starter.
Blow through motor and starter with dry compressed air at 2 Kg/Cm
2
.
Check tightness of cable connections.
Check motor for overheating and abnormal noise / sound, sparking and for proper
bedding of brushes.
Tighten belts and pulleys to eliminate excessive losses.
iv). Quarterly: ‐
Check motor terminal voltage for balanced supply. If more than +1% of average, then
check from transformer onward.
Carry out SPM checks viz. vibrations and sound of bearing. Record reading and
compare With earlier / other motor readings.
Slip Ring: ‐ Inspect the brushes and make sure that they move freely in the
brush holder clips.
Clean brushes, holder chip and wipe with cloth dipped and in gasoline. Replace
the brush if they are worn out less than 5 mm in length from brush holder.
Clean the starter and motor contacts with white spirit.
v). Six Monthly Maintenance: ‐
Check over load mechanism of starter.
Check alignment of motor with driven equipment.
Check no load current and compare with earlier / original.
Check / change lubrication as per lubrication schedule given on next pages.
Check the securing foundation nuts for tightness.
Inspect the paint coating and do‐touching wherever required.
Check IR(Insulation) Resistance of motor and starter with 500 V megger. It should be
more than 2 MΩ