Power Plant Engineering
Content
* M.P.NACHIMUTHU M.JAGANATHAN ENGINEERING COLLEGE B.E. DEGREE EXAMINATION EE 2252 - Power Plant Engineering
SHORT UESTIONS AN! ANS"ERS
#. Na$e t%e &o'r $a(or )ir)'it* in *tea$ +ower +lant. • • • • Coal and ash circuit Air and flue gas circuit Feed ater and stea! circuit Cooling ater circuit
2. "%at )on*i*t* o& air an, &l'e ga* )ir)'itAir and flue gas circuit consists of forced draught fan" air#$re#heater" %oiler" furnace" su$er heater" econo!iser" dust collector" induced draught fan and chi!ne&. .. "%at )on*i*t* o& &ee, water an, *tea$ &low )ir)'it in *tea$ +owerThe feed ater and stea! flo su$er heater" tur%ine and condenser. circuit consists of feed $u!$" econo!iser %oiler dru!
/. "%at )on*i*t* o& )ooling water )ir)'it an, )oal 0 a*% )ir)'it in *tea$ +ower +lantThe cooling ater circuit consists of a $u!$" condenser and cooling to er. The coal and ash circuit consists of coal deli'er&" $re$aration of coal" handling of coal to the %oiler furnace" ash handling and ash storage. 5. "%at i* t%e $ain +'r+o*e o& t%e re*er1oirThe !ain $ur$ose of reser'oir is to store ater recei'ed fro! catch!ents areas during the rain& seasons and su$$l& the sa!e during the dr& season. 2. "%at i* t%e $ain +'r+o*e o& t%e ,a$The !ain $ur$ose of the da! is to increase the height of the or(ing head of the h&draulic $o er $lant. 3. "%4 tra*% ra)5 i* '*e,The trash rac( is used to $re'ent the entr& of de%ris" runners and choc( u$ the no))le of i!$ulse tur%ine. 6. "%at i* t%e '*e o& *'rge tan5The surge tan( is used to $ro'ide %etter regulation of ater $ressure in the s&ste!. The surge tan( controls the ater hen the load on the tur%ine decreases and su$$lies ater hen the load on the tur%ine increases. Thus" surge tan( controls the $ressure 'ariations resulting fro! the ra$id changes in ater flo in $enstoc( and hence $re'ents ater ha!!er. 7. "%at i* t%e &'n)tion o& 8ore 9a4hich !ight da!age the tur%ine ater le'el and also to increase
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Fore %a& is considered as naturall& $ro'ided surge tan(. It is te!$orar& ater storage hen the load on the $lant is reduced and $ro'ides ater for initial incre!ent on increasing load. #:. E;+lain a9o't +en*to)5The $i$e %et een surge tan( and $ri!e !o'er is (no n as $enstoc(. It is designed to ithstand high $ressure. It is !ade u$ of reinforced concrete. In 'er& cold areas" the $enstoc( is %uried to $re'ent ice for!ation and to reduce the e+$ansion ,oints. ##. "%at i* t%e '*e o& *+ill "a4*-$ill a& is li(e a safet& 'al'e of the da!. It discharges !a,or flood da!. It (ee$s the reser'oir le'el %elo the !a+i!u! le'el allo ed. #2. "rite a9o't +ri$e $o1er*.ri!e !o'er con'erts the (inetic energ& of ater into !echanical energ& to $roduce electrical energ&. .elton heel" tur%ine" Francis tur%ine" /a$lan tur%ine and .ro$eller tur%ine are $ri!e !o'ers used in h&draulic $o er $lants. #.. "%at are t%e '*e* o& air &ilter an, *'+er)%arger* in ,ie*el engine +ower +lantThe $ur$ose of air filter is to filter the air fro! dust and other sus$ended $articles. The $ur$ose of su$er charger is to increase the $ressure of the engine to increase $o er of the engine. #/. "%at i* t%e '*e o& ,ra&t t'9eThe draft tu%e is used to regain the (inetic energ& of ater co!ing out of reaction tur%ine. It ena%les the reaction tur%ine to %e $laced o'er tailrace le'el. #5. "%at i* t%e &'n)tion-o& )ooling *4*te$ in !ie*el +ower +lantThe function of cooling s&ste! is to re!o'e heat fro! the engine c&linder to (ee$ the te!$erature of the c&linder in lo range and e+tend engine life. #2. "%at )on*i*t* o& l'9ri)ation *4*te$ in ,ie*el engine +ower +lantThe lu%rication s&ste! consists of oil $u!$s" oil tan(s" filters" coolers and connecting $i$es. The $ur$ose of the lu%rication is to reduce the friction of !o'ing $arts and also $i$es to reduce the ear and tear of !o'ing $arts. #3. "%at i* t%e +'r+o*e o& inter)ooler in ga* t'r9ine +ower +lant-ince the $o er re0uired to co!$ress the air is less in isother!al $rocess it is re0uired to !aintain the" te!$erature of air constant as far as $ossi%le. 1ence the air lea'ing the 2... co!$ressor is cooled %& intercooler and then $assed to the 1.. co!$ressor. #6. Na$e two )o$9ine, +ower )4)le*• • Co!%ined c&cle of gas tur%ine and stea! $o er $lant. Co!%ined c&cle of gas tur%ine and diesel $o er $lant. ithout da!aging the
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#7. !e&ine t'r9o )%arging in )o$9ine, ga* t'r9ine an, ,ie*el )4)le*In the co!%ined c&cle" the e+haust gas fro! the diesel engine is e+$anded in the tur%ine" hich is cou$led ith co!$ressor hich su$$lies $ressuri)ed air to the diesel engine. This increases diesel engine out$ut. This arrange!ent is (no n as tur%o charging. 2:. "%at i* t%e $ain +'r+o*e o& %ig%-+re**'re 9oiler*The high#$ressure %oilers are used to increase the efficienc& of the $lant and to reduce the cost of electricit& $roduction. 2#. State i$+ortant a,1antage* o& %ig%-+re**'re 9oiler*• • The a!ount of scale for!ation is less" since the 'elocit& of ater through $i$es are !ore. All $arts of the s&ste! are heated unifor!l&" so there is no danger of o'erheating.
22. Na$e i$+ortant %ig% +re**'re 9oiler*• • • • 2a Mont %oiler Benson %oiler 2oeffler %oiler 4elo+ %oiler.
2.. "rite a9o't La Mont 9oiler- "%at i* t%e $a(or ,i*a,1antage o& La Mont 9oiler2a Mont %oiler is a forced circulation high $ressure ater tu%e %oiler. The !a,or disad'antage is the for!ation of %u%%les" salt and sedi!ent on the inner surfaces of the heating surfaces. This reduces the heat flo and stea! generation.
2/. "rite a9o't <en*on 9oiler- State *o$e i$+ortant a,1antage* o& <en*on 9oilerBenson %oiler is the high $ressure" 'ertical fire tu%e %oiler. This %oiler has no dru! and is 5designed to o$erate at critical $ressure of 336 %ar. Benson %oiler has no dru!. -o the total eight of the Benson %oiler is reduced %ź" hen co!$ared to other %oilers. o The erection of Benson %oiler is easier and 0uic(er. 25. "rite a9o't Loe&&ler 9oilerThe !a,or disad'antage in 2a Mont %oiler is the de$osition of salt and sedi!ent on the inner surface of the ater tu%es. It reduces the heat transfer and ulti!atel& the stea! generating ca$acit&. In 2oeffler %oiler" this $ro%le! is sol'ed %& $re'enting ater fro! flo ing through the %oiler tu%es. The stea! is generated outside the tu%es. 22. E;+lain Re%eat )4)leIf the dr&ness fraction of stea! lea'ing the tur%ine is less than 7.99" then" corrosion and erosion of tur%ine %lades occur. To a'oid this situation" reheat is used.
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In the reheat c&cle" the e+$ansion of stea! ta(es $lace in one ;or< !ore#tur%ines. -tea! is e+$anded in the 1. tur%ine first" and then it is reheated. The reheated stea! is again e+$anded in. the 2. tur%ine. 23. "%at are t%e i$+ortant a,1antage* o& Re-%eating• • • • Due to reheating" net or( done increases 1eat su$$l& increases Ther!al efficienc& increases Due to reheating" the tur%ine e+it dr&ness fraction increases so !oisture decreases # so %lade erosion %eco!es !ini!u! # so life of the tur%ine ill %e increased.
26. Na$e ,i&&erent $et%o,* o& re%eating;a< Gas Reheating ;%< 2i'e # stea! reheating ;c< Co!%ined gas li'e stea! reheater. 27. !e&ine 9lee,ing in *tea$ +ower +lantAssu!e I (g of stea! is e+$anded in the tur%ine. Before co!$lete a!ount of stea! #is e+$anded" so!e a!ount of stea! ;! (g< is #e+tracted = E+tracting the stea! in the tur%ine %efore e+haust is called %leeding. This %led stea! is used to heat the feed ater. .:. E;+lain t%e ter$ RegenerationRegeneration !eans heating the feed ater %& stea! ta(en fro! the tur%ine. The stea! is e+hausted ;%led< fro! the tur%ine at se'eral locations %efore e+haust and is su$$lied to regenerator ;feed ater heater< to heat the feed ater. .#. State *o$e a,1antage* o& Regeneration )4)le• • • 1eat su$$lied to %oiler %eco!es reduced Ther!al efficienc& is increased since the a'erage te!$erature of heat addition to the c&cle is increased. Due to %leeding in the tur%ine" erosion of tur%ine due to !oisture is reduced.
.2. Na$e ,i&&erent $et%o,* '*e, to e;tra)t *tea$ &or %eating t%e &ee, water• • • • Direct contact heater Drain $u!$ !ethod All drains to hot ell Cascade s&ste!
... !e&ine t%e ter$ wa*te %eat re)o1er4>aste heat is the heat hich is not at all used and e+hausted out as a aste $roduct. >aste heat is nor!all& a'aila%le fro! the industr& in the for! of $rocess stea! and ater at high te!$erature. Also" the aste heat is discharged ith the e+haust gases in so !an& industries. This heat can %e reco'ered for useful $ur$ose. This $rocess is (no n#as aste heat reco'er&. ./. "%at are t%e wa*te $aterial*= w%i)% )an 9e '*e, &or &'el &or +ower generation-
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• Munici$al aste • Industrial aste • .a$er aste • Ru%%er aste. .5 "rite a9o't wa*te %eat 9oiler*The aste heat %oilers use the aste heat in gases co!ing out of diesel engines and gas tur%ines at high te!$erature ;or< use the aste as a fuel in the incineration. -o!e %oilers use the industrial dirt& gases for $o er generation. .2. "rite a9o't &l'i,i*e, 9e, 9oiler*>hen the high 'elocit& gas is $assed through a $ac(ed %ed of finel& di'ided solid $articles" the $articles %eco!e sus$ended in the gas strea! and the $ac(ed %ed %eco!es a fluidised %ed. >hen the gas 'elocit& is 'er& high" the fluidised %ed %eco!e tur%ulent and ra$id !i+ing of $articles occurs. @lti!atel&" the" %eha'iour of !i+ture solid $articles and #gas %eco!e a fluid. Burning of a fuel in such a state is (no n as Fluidised Bed Co!%ustion. The %oiler $lant using this fluidised %ed co!%ustion is (no n as fluidised %ed %oilers. .3. State *o$e a,1antage* o& &l'i,i*e, 9e, 9oiler*• • • • An& t&$e of fuel # solid" li0uid ;or< gaseous fuel ;or< do!estic and industrial aste can %e used in FBC s&ste!. An& t&$e# of co!%usti%le !atter can %e %urned %& ad,usting the factors as si)e" air 'elocit& and rate of feed. 1igh heat transfer rate is $ossi%le to the surfaces i!!ersed in the %ed" %ecause solid !i+ing is e+tre!el& $ossi%le. 1igh co!%ustion efficienc&. The solid fuel need not %e $ul'erised in fluidised %ed %oilers.
.6. Na$e t%e two t4+e* o& )oal %an,ling• • Out $lant handling In#$lant handling.
.7. "rite a9o't o't-+lant %an,lingOut $lant handling includes the handling of coal!ine to the ther!al $o er $lant. These handlings are outside the $lant in the follo ing a&s. • Trans$ortation %& sea ;or< ri'er • Trans$ortation %& rail • Trans$ortation %& road • Trans$ortation of coal %& $i$eline. /:. "rite a9o't in+lant %an,ling o&-)oalIn order to handle large 0uantit& of coal inside the $lant" so!e !echanical handling s&ste!s are $ro'ided fAr s!ooth" eas& and %etter controlled o$eration. The in$lant coal handling is di'ided" into follo ing categories. • Coal unloading • Coal $re$aration • Coal transfer • Coal storage
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/#. "%4 t%e +re+aration o& )oal i* ne)e**ar4The coal fro! coal nines cannot %e directl& fed into the furnace. .ro$er $re$aration of coal should %e done %efore feeding the coal to the furnace. In the coal $re$aration" the coal $asses through the different e0ui$!ents li(e *. Crushers 3. -i)ers :. Driers and Magnetic -e$arators. /2. Na$e t%e ,i&&erent t4+e* o& )oal tran*&or$ing e>'i+$ent**. Belt con'e&ors 3. -cre con'e&ors :. Buc(et ele'ators ?. Gra% %uc(et ele'ators 6. -(i$ hoists A. Flight con'e&ors. The coal transfer starts %& carr&ing of coal fro!#unloading $oint to the storage site. /.. "%at i* t%e '*e o& 9elt )on1e4or*Belt con'e&ors are !ostl& used for trans$orting coal o'er long distance ith large 0uantit&. An endless %elt is !ade to run o'er a $air of end dru!s and $ulle&s and su$$orted %& series of roller at regular inter'als. //. "rite a9o't *)rew )on1e4or an, 9')5et )on1e4or*In scre con'e&or" an endless helicoid scre is fitted to the Bhaft. On one end of the shaft" the dri'ing !echanis! is fitted and the other end of the shaft is su$$orted on a %all %earing. >hile the scre is rotating" the coal is transferredC fro! one end to the other end. Buc(et con'e&ors are used as 'ertical lifts. The coal is loaded at the %otto! and unloaded at the to$ in the %uc(et con'e&ors. /5. !e&ine ,ra'g%t= w%at i* t%e '*e o& ,ra'g%t in t%er$al +ower +lant*Draught is defined as a s!all $ressure difference re0uired %et een the fuel %ed ;furnace< and outside air to !aintain constant flo of air and to discharge the gases through chi!ne& to the at!os$here. Draught can %e o%tained %& chi!ne&" fan" stea! ,et ;or< #air ,et ;or< co!%ination of these. The uses are • To su$$l& re0uired 0uantit& of air to the furnace for co!%ustion of fuel. • To dra the co!%ustion $roducts through the s&ste!. • To re!o'e %urnt $roducts fro! the s&ste! /2. "rite a9o't )la**i&i)ation o& ,ra'g%tDraught is classified as *. Natural draught 3. Artificial draught The artificial draught is further classified as ;a< -tea! ,et draught ;%< Mechanical draught ;c< Induced draught ;d< Forced draught /3. !e&ine t%e ter$ Nat'ral ,ra'g%t an, w%at are t%e a,1antage* o& nat'ral ,ra'g%t *4*te$-
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The tall chi!ne& creates the natural draught %& the te!$erature difference %et een hot gases in the chi!ne& and cold at!os$heric air outside the chi!ne&. The ad'antages are • No e+ternal $o er is re0uired • Air $ollution is less since gases are discharged at high le'el. • No !aintenance cost • Ca$ital cost is less than artificial draught. /6. "rite a9o't arti&i)ial ,ra'g%tIn !ode! $o er $lants" the draught should %e fle+i%le to !eet the fluctuating loads and it should %e inde$endent of at!os$heric conditions. To achie'e this" the aid of draft fans %eco!es !ust and %& e!$lo&ing the draft fans" the height of the chi!ne& ould %e reduced. /7. "rite a9o't &or)e, ,ra'g%t *4*te$In this s&ste!" the %lo er ;forced draft fan< is located at the %ase of the %oiler near the grate. Air is forced to the furnace %& forced fan and the flue gases are forced to chi!ne& through econo!iser and air $reheater. 5:. "%at are t%e a,1antage* o& &or)e, ,ra'g%t *4*te$ • • • -ince the fan handles cold air" the fan si)e and the $o er re0uired are less. No need of ater cooled %earings %ecause the air %eing handled is cold air" .ressure throughout the s&ste! is a%o'e at!os$heric $ressure so the air lea(age into the furnace is reduced.
5#. How t%e in,')e, ,ra'g%t i* wor5ingIn an induced draught s&ste!" a %lo er ;induced draft fan< is $laced near ;or< at the %ase of the chi!ne&. The fan suc(s the flue gas fro! the furnace creating a $artial 'acuu! inside the furnace. Thus at!os$heric air is induced to flo through the furnace to aid the co!%ustion of fuel. The flue gases dra n %& the fan $asses through chi!ne&" to the at!os$here. 52. "%4 t%e 9alan)e, ,ra'g%t *4*te$ i* +re&erre, t%an ot%er *4*te$In the induced draught s&ste!" hen the furnace is o$ened for firing" the cold air enters the furnace and dilate the co!%ustion. In the forced draught s&ste!" hen the furnace is o$ened for firing" the high $ressure air ill tr& to %lo out suddenl& and furnace !a& sto$. 1ence the furnace cannot %e o$ened for firing ;0< ins$ection in %oth" s&ste!s. Balanced draught" hich is a co!%ination of induced and forced draught" is used to o'erco!e the a%o'e stated difficulties. 5.. "%at i* t%e ,i&&eren)e 9etween *to)5er &iring an, +'l1eri*e, &'el &iringThe stoc(er firing !ethod is used for firing solid coal here as $ul'erised firing !ethod is used for firing $ul'erised coal. 5/. "%at are-t%e ,i&&erent t4+e* o& *to)5er**. O'er feed stoc(ers Tra'elling grate stoc(ers -$read stoc(ers 3. @nder feed stoc(ers -ingle retort stoc(er Multi retort stoc(er
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55. "%at i* t%e '*e o& +'l1eri*er an, na$e ,i&&erent t4+e* o& +'l1eri*ing $ill*The $ul'eriser is used to $ul'erise the coal in order to increase the surface e+$osure. .ul'erised coal ena%les ra$id co!%ustion. The different t&$es of $ul'erising !ills are *. Ball !ill 3. 1a!!er !ill :. Ball and race !ill. 52. Na$e t%e two $et%o,* o& +'l1eri*e, &'el &iring *4*te$*. @nit ;or< direct s&ste! 3. Bin ;or< central s&ste!. 53. "%at are a,1antage* o& 'nit ?or@ ,ire)t *4*te$ o& +'l1eri*e, &'el &iring*. The la&out is si!$le and econo!ical 3. It gi'es direct control of co!%ustion :. Coal trans$ortation s&ste! is si!$le ?. Maintenance cost is less 56. How t%e a*% %an,ling *4*te$ i* )la**i&ie,*. Mechanical handling s&ste! 3. 1&draulic s&ste! :. .neu!atic s&ste! ?. -tea! ,et s&ste! 57. "%4 a*% %an,ling *4*te$ i*A nee,e,• • • To re!o'e the ashes fro! the furnace ash ho$$er To trans$ort the ashes fro! furnace ash # ho$$er to a storage To dis$ose the ashes fro! the storage
2:. Na$e ,i&&erent t4+e* o& ,'*t )olle)tor**. Mechanical Dust collector Gra'itational se$arators Bag house dust collector There are three t&$es of %ag house dust collector • O$en $ressure t&$e • Closed $ressure t&$e • Closed suction t&$e 3. C&clone. -e$arators :. Elector -tatic .reci$itator ;E-.< 2#. "%at i* t%e $ain +'r+o*e o& )%i$ne4The !ain $ur$ose of chi!ne& is to e!it the flue gases at a considera%le height to a'oid nuisance to the surrounding $eo$le. 22. "%at are t%e ,i&&erent t4+e* o& loa, a)t on t%e )%i$ne4There are t o t&$es of loads acting on the chi!ne& na!el&.
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• • Its o n eight hich is considered to as a single 'ertical force acting through the centroid" and The >ind $ressure" hich is considered as the hori)ontal force acting on the centroid of 'ertical $ro,ected area.
2.. Na$e ,i&&erent t4+e* o& )%i$ne4*. -teel chi!ne& 3. -ite constructed chi!ne& :. .lastic chi!ne& 2/. !e&ine &or)e, ,ra&t an, in,')e, ,ra&t )ooling tower*
If the fan is located at the %otto! of the to er and air is %lo n %& the fan u$ through the descending ater it is called as forced draft cooling to ers If the fan is located at the to$ of the to er and air enters through the lou'ers located on the to erEs side and dra n u$ and discharge through the fan casing" it is called as induced draft. 25. "%at are t%e a,1antage* o& in,')e, ,ra&t )ooling tower o1er &or)e, ,ra&t )ooling toweri. The outlet ater co!es in contact ith the driest air and ar!est ater co!es in contact ith !ost hu!id air. ii. The re#circulation is seldo! a $ro%le!. iii. The first cost is lo due to the reduction in $u!$ $o er consu!$tion. 22. "%at are t%e a,1antage* o& %4+er9oli) nat'ral-,ra&t )ooling tower*• • • • -ince no fans are used $o er cost and au+iliar& e0ui$!ents cost is reduced. 1&$er%olic to er chi!ne& creates its o n draft e'en hen there is no ind Ground fogging and ar! air re#circulation are a'oided in h&$er%olic to ers The structure is !ore or less self#su$$orted.
23. "%at are t%e &a)tor* t%at a&&e)t t%e rate o& e1a+oration o& water in )ooling tower*• • • • • A!ount of ater surface area e+$osed The ti!e of e+$osure The relati'e 'elocit& of air $assing o'er the dro$lets The R1 of air The direction of airflo relati'e to ater.
26. "%at i* t%e wor5ing +rin)i+le o& Cooling Tower*The hot ater is s$ra&ed fro! the to$ of the to er" hile the air is !ade to flo fro! the %otto! of the to er to the to$. This air cools the hot ater in the cooling to er. Air 'a$orises a s!all $ercentage of ater" there %& cooling the re!aining ater. The air a%sor%s the heat and lea'es at the to$ of the to er and cooled ater lea'es at the %otto! and recirculated to the condenser.
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27. Na$e ,i&&erent t4+e* o& )ooling tower*The cooling to ers are classified as follo s. ;a< According to the construction of !aterial *. Ti!%er # for s!all to er 3. Ferro concrete # for large ca$acit& stations. :. Multi dec( concrete to ers # for large stea! stations ?. Metallic ;%< According to the nature of air draught# *. At!os$heric ;or< Natural draught cooling s&ste! 3. Mechanical draught cooling to er. 3:. How t%e at$o*+%eri) ?or@ nat'ral ,ra'g%t )ooling tower*- are )la**i&ie,In at!os$heric ;or< natural cooling to ers" the natural air $ro'ides the re0uired cooling ithout the use of fans. This is classified into three t&$es. *. Natural draft s$ra& filled to ers 3. Natural draft $ac(ed t&$e to ers.= :. 1&$er%olic cooling to ers 3#. How $e)%ani)al ,ra&t )ooling tower* are )la**i&ie,Mechanical draft cooling to er is classified into three t&$es *. Forced draft to er. 3. Induced draft counter flo to er :. Induced draft cross flo to er. 32. How t%e ,r4 t4+e )ooling tower* are )la**i&ie,The dr& t&$e cooling to ers are classified into t o t&$es =as follo s. *. Indirect dr& t&$e ;or< 1eller cooling s&ste! 3. Direct dr& t&$e#cooling s&ste! 3.. "%at are t%e $et%o,* to re,')e t%e e&&e)t* o& +arti)'late*The effects of $articulates can %e reduced %& the follo ing !ethods. • Coal cleaning • @sing i!$ro'ed electrostatic $reci$itator design • Controlling the dust ithin allo a%le li!it. This can %e done %& increasing the height of chi!ne& there%& reducing the concentration 3/. "%at are t%e e>'i+$ent* '*e, &or a*% )olle)tion• • • • Electrostatic $reci$itator Fl& ash scru%%ers Cinder catcher C&clone dust collector
35. "%at i* $eant 94 A!e*'l+%'ri*ationA an, na$e t%e $et%o,* a,o+te, &or ,e*'l+%'ri*ation-
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Desul$hurisation of fuel is the $rocess of reducing the sul$hur content in the fuel. The follo ing !ethods are ado$ted for desul$hurisation. *. Che!ical treat!ent 3. Forth flotation :. Magnetic se$aration 32. "%at are t%e $et%o,* a,o+te, to re$o1eA S:2 &l'e ga*e**. >et scru%%ing 3. -olid a%sor%ent :. Catal&tic o+idation 33. "rite a9o't C:2 re)or,er*In ther!al $o er $lants" it is necessar& to (ee$ the concentration Of C73 as lo is necessar& as $ossi%le. To achie'e this" a constant recording of concentration Of C73 These recorders are %ased on the three different $rinci$les" as gi'en %elo . *. Ther!al conducti'it& cell 3. Che!ical a%sor$tion cell :. Densit& %alance B3. >hat is the# necessit& of Auto!atic controls for feed aterF The electrical load on $o er $lant 'aries in an irregular !anner. The auto!atic control $ro'ided at a stea! $o er $lant successfull& !eets o'er the 'aria%le load. The auto!atic control for feed ater is necessar& sine the su$$l& of feed ater de$ends u$on $lant load. 36. Na$e *o$e o& t%e a'to$ati) )ontrolling $et%o,* &or &ee, water*. -ingle ele!ent $ilot o$erated s&ste! 3. -ingle ele!ent self o$erated s&ste! :. T o ele!ent $ilot o$erated s&ste! ?. Three ele!ent $ilot o$erated s&ste! 37. "%at i* t%e +'r+o*e o& a'to$ati)= )o$9'*tion )2#ritrolThe !ain $ur$ose of #auto!atic co!%ustion= control s&ste! is to !aintain load against de!and" to $re'ent s!o(e" to increase %oiler house efficienc&" to carr& out routine ad,ust!ents and to $ro'ide interloc(ing safe guards. 6:. "%at are t%e a++lian)e* 5nown a* 9oiler a))e**orie*The a$$liances used to increase the efficienc& of the %oiler are (no n as %oiler accessories. The i!$ortant %oiler accessories are *. Econo!iser 3. -u$erheater :. Air $reheater ?. Feed $u!$ 6. In,ector 6#. "%at are t%e $et%o,* a,o+te, to re$o1e SO 2 &ro$ ,'e ga*e**. >et scru%%ing 3. -olid a%sor%ent :. Catal&tic o+idation 62. "rite a9o't C:2 re)or,er*In ther!al $o er $lants" it is necessar&" to (ee$ the concentration of C73 as lo as $ossi%le. To achie'e this = a constant recording of concentration of C73 is necessar&.
*3
These recorders are %ased on the three different $rinci$les" as gi'en %elo . *. Ther!al conducti'it& cell 3. Che!ical a%sor$tion cell :. Densit&# %alance 6.. "%at i* t%e ne)e**it4 o& A'to$ati) )ontrol* &or &ee, waterThe electrical load on $o er $lant 'aries irregular !anner. The auto!atic !an control $ro'ided at a stea! $o er $lant successfull& !eets o'er the 'aria%le load. The auto!atic control for feed ater is necessar& sine the su$$l& of feed ater de$ends u$on $lant load. 6/. Na$e *o$e o& t%e a'to$ati) )ontrolling $et%o,* &or &ee, water• • • • A single ele!ent $ilot o$erated s&ste! -ingle ele!ent self o$erated s&ste! T o ele!ent $ilot o$erated s&ste! Three ele!ent $ilot o$erated s&ste!
65. "%at i* t%e +'r+o*e o& a'to$ati) )o$9'*tion )ontrolThe !ain $ur$ose auto!atic co!%ustion control s&ste! is to !aintain load ad,ust de!and" to $re'ent s!o(e" to increase %oiler house efficienc&" to carr& out routine ad,ust!ents and to $ro'ide interloc(ing safe guards. 62 "%at i* t%e '*e o& air +re%eaterAir $re heater is used to transfer heat fro! the flue gases to the air %efore it $asses into the furnace for co!%ustion. It is $laced %et een the econo!i)er and chi!ne&. The o'erall efficienc& of the $lant !a& %e increased %& *7 $er cent %& the use of air $reheater. 63. "rite a9o't 9oiler $o'nting*The de'ices used for the efficient o$eration" $ro$er !aintenance" and safe o$eration %oiler !ountings. The different %oiler !ountings are *. >ater gauge ;or< ater le'el indicator 3. .ressure gauge ;or< stea! gauge :. -afet& 'al'es ?. Fusi%le $lug 6. -to$ 'al'e A. Blo off coc( D. Feed chec( 'al'e. 66. "%at i* $eant 94 9oiler trial-tea! is generated in %oilers under certain conditions of feed ater and e+ists as stea! hile a certain a!ount of fuel is %urnt. To stud& the $erfor!ance of %oiler" so!e e+$eri!ents are conducted %& o$erating" the %oiler for a certain length of ti!e and recording the data. This $rocedure is (no n as %oiler trial. 67. State t%e o9(e)ti1e o& 9oiler trial*.To deter!ine the ther!al efficienc& of the %oiler hen or(ing at a definite $ressure. 3.To dra u$ heat %alance sheet for the %oiler to chec( the $erfor!ance of the %oiler.
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7:. !e&ine ,e$an, &a)tor• • • De!and factor is defined as the ratio of !a+i!u! de!and to connected load. Connected load is the su! of ratings in (> of e0ui$!ent installed in the consu!er=s $re!ises. Ma+i!u! de!and is the !a+i!u! load" hich a consu!er uses at an& ti!e.
7#. !e&ine loa, )'r1e2oad cur'e is a gra$hical re$resentation %et een load in (> and ti!e in hours. It. sho s 'ariatiAn of load at the $o er station. The area under the load cur'e #re$resents the energ& generated in a $articular $eriod. 72. !e&ine loa, &a)tor2oad factor is defined as the ratio of a'erage load to the $ea( load ;or< !a+i!u! de!and. 7.. "%at in)l',e* &i;e, )o*tFi+ed cost includes the follo ing cost. *. Cost of land 3. Cost of %uilding :. Cost of e0ui$!ent ?. Cost of installatiAn 6. Interest A. De$reciation cost D. Insurance 9. Manage!ent cost 7/. "%at in)l',e* o+erating )o*tO$erating cost includes the follo ing cost. *. Cost of fuel 3. Cost of o$erating la%our" :. Cost of !aintenance la%ours and !aterials. ?. Cost of su$$lier li(e >ater for feeding %oilers" for condenser and for general use. 2u%rication oil and" grease. >ater treat!ent che!icals. 75. "%at i* t%e nee, o& ,e+re)iation )o*tDe$reciation cost is the a!ount to %e set aside $er &ear fro! the inco!e of the $lant to !eet the de$reciation caused %& the age of ser'ice" ear and tear of the !achiner& and e0ui$!ents. De$reciation a!ount collected e'er& &ear hel$s in re$lacing and re$airing the e0ui$!ent. 72. "rite a9o't ato$i) n'$9erThe nucleus contains $rotons and neutrons. The nu!%er of $rotons in a gi'en ato! is an ato!ic nu!%er ;G<. The ato!ic nu!%er for 1 is * and 1e #is 3. 73. "rite a9o't i*oto+e* o& an ele$ent-o!e ele!ents ha'e the sa!e nu!%er of $rotons in the nucleus %ut different nu!%er# of neutrons. As a result" these ele!ents ha'e the sa!e ato!ic nu!%er %ut different !ass nu!%er. -uch t&$e of ele!ents hich = ha'e the sa!e ato!ic nu!%er H sa!e nu!%er of $rotons # the #sa!e che!ical $ro$erties %ut different !ass nu!%ers due to different nu!%er of neutrons" are (no n as I the isoto$es of an ele!ent.
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76. "%at are t%e re>'ire$ent* to *'*tain &i**ion +ro)e**• • • • The %o!%arded neutrons !ust ha'e sufficient energ& to cause fission The nu!%er of neutrons $roduced !ust %e a%le to create the rate of fission The fission $rocess !ust generate energ& The fission $rocess !ust %e controlled
77. !e&ine $'lti+li)ation &a)tor o& a &i**ion +ro)e**. nu!%er of neutrons of an& one generation (I nu!%er of neutrons of i!!ediatel& $receding generation. #::. !e&ine &ertile $aterial* an, 9ree,ing in rea)tor* There are !aterials li(e @3:6 and Th3:3 hich are not fissile %ut can %e con'erted into fissile !aterials %& the %o!%ard!ent of neutrons. -uch !aterials are (no n as fertile !aterials. The $rocess of con'erting !ore fertile !aterial into fissile !aterial in a reaction is (no n as %reeding. #:#. "%at are t%e ,e*ira9le +ro+ertie* o& a goo, $o,erator• It !ust %e as light as $ossi%leIt !ust slo do n the neutron as 0uic( as $ossi%le • It !ust ha'e resistance to corrosion • It !ust ha'e good !achina%ilit& • It !ust ha'e good conducti'it& and high !elting $oint #:2. "%at are t%e ,e*ira9le +ro+ertie* o& a )oolant• It should not a%sor% neutron • 1a'e high che!ical and radiation sta%ilit& • Non#corrosi'e • 1a'e high %oiling $oint • Non#to+ic #:.. Na$e &ew t4+e* o& rea)tor*. Fast reactors" Ther!al reactors" natural fuel reactors" Enriched @raniu! reactors" ater !oderated reactors" hea'& ater !oderated reactor" gra$hite !oderated reactor" gas cooled reactors and -odiu! cooled reactors. #:/. "%at are t%e a,1antage* '*ing CO2 a* )oolant• Gases do not react che!icall& ith the structural !aterials • Gas can attain an& te!$erature for a $articular $ressure • The& do not a%sor% neutron • The lea(age of gas ill not affect the reacti'it& • The gas coolant $ro'ides %est neutron econo!& #:5. "%at are t%e a,1antage* o& 9ree,er rea)tor*• It gi'es high $o er densit& than an& other reactor • 1igh %reeding is $ossi%le • 1igh %urn#u$ of fuel is achie'a%le
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• The o$eration of the reactor is not li!ited %& Xe $oisoning
#:2. "%at are t%e ,e$erit* o& 9ree,er rea)tor• 1ighl& enriched fuel is re0uired • Control is difficult and e+$ensi'e • -afet& !ust %e $ro'ided against !elt do n • 1andling of sodiu! is a !a,or $ro%le! #:3. "%at are t%e a,1antage* o& So,i'$ in &a*t-9ree,er rea)tor*• -odiu! has 'er& lo a%sor$tion cross#sectional area • It $osses good heat transfer $ro$erties at high te!$erature and lo $ressure • It does not react ith an& of the structural !aterials used in $ri!ar& circuits #:6. Na$e t%e ,i&&erent t4+e* o& MH! generator* • O$en c&cle M1D • Closed c&cle M1D • Closed c&cle M1D ith li0uid !etal #:7. "%at i* t%e wor5ing +rin)i+le o& $agneto %4,ro,4na$i) +ower +lantThe or(ing $rinci$le of M1D is as li(e that of d&na!o. Instead of solid conductor high te!$erature $las!a is $assed through the !agnetic field at sonic s$eed. >hen the gas is $assed through !agnetic field" current is induced. Electrodes collect this induced current. ##:. "%at i* t%e +'r+o*e o& )ontrol ro,*The control rods are used to start the chain reaction" !aintain the chain reaction at re0uired le'el and to shut do n the reactor during e!ergenc&. ###. "%at are t%e ,i&&erent t4+e* o& loa, a)ting on t%e )%i$ne4• Its o n eight hich is considered to act on a single 'ertical force acting through the centroid • The ind $ressure" hich is considered to act on the hori)ontal force acting on the centroid of 'ertical $ro,ected area.
##2. "%at i* $eant 94 N')lear &i**ion@raniu! e+ists in different isoto$es of @3:9" t.:? and @3:6. Out of these" E.:6 is !ost unsta%le. >hen unsta%le hea'& nucleus is %o!%arded ith high#energ& neutrons" it s$lits u$ roughl& into t o e0ual frag!ents and a%out 3.6 neutrons are released and a large a!ount of energ& is $roduced. This $rocess is called nuclear fission. ##.. Na$e t%e ,i&&erent )o$+onent* o& n')lear rea)tor*. Nuclear fuel 3. Moderator :. Control rods ?. Reflectors 6. Reactor 'essel A. Biological shielding D. Coolant ##/. • • State *o$e a,1antage* o& Pre**'riBe, "ater rea)torThe $ressuri)ed ater reactor is co!$act In this t&$e" ater is used as coolant" !oderator and reflector ater is a'aila%le in $lent&< • It re0uires less nu!%er of control rods. ##5. "%at are t%e a,1antage* o& ga* )oole, rea)tor n')lear +ower +lant-
chea$
and
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*. Fuel $rocessing is si!$le 3. The use of C73 as coolant co!$letel& eli!inates the $ossi%ilit& of e+$losion in reactor. :. No corrosion $ro%le! ##2. "%at i* 9ree,ing in n')lear rea)torThe $rocess of $roducing fissiona%le !aterial fro! a fertile !aterial such as uraniu! 3:9 ;@3:9< and thoriu! 3:3 ;Th 3:3 < %& neutron a%sor$tion is (no n as %reeding. ##3. Na$e t%e )oolant* )o$$onl4 '*e, &or &a*t 9ree,er rea)tor*2i0uid !etal ;Na ;or< Na /< 1eliu! ;1e< Car%on dio+ide.
SHORT UESTIONS AN! ANS"ERS
#. Na$e t%e &o'r $a(or )ir)'it* in *tea$ +ower +lant. • • • • Coal and ash circuit Air and flue gas circuit Feed ater and stea! circuit Cooling ater circuit
2. "%at )on*i*t* o& air an, &l'e ga* )ir)'itAir and flue gas circuit consists of forced draught fan" air#$re#heater" %oiler" furnace" su$er heater" econo!iser" dust collector" induced draught fan and chi!ne&. .. "%at )on*i*t* o& &ee, water an, *tea$ &low )ir)'it in *tea$ +owerThe feed ater and stea! flo su$er heater" tur%ine and condenser. circuit consists of feed $u!$" econo!iser %oiler dru!
/. "%at )on*i*t* o& )ooling water )ir)'it an, )oal 0 a*% )ir)'it in *tea$ +ower +lantThe cooling ater circuit consists of a $u!$" condenser and cooling to er. The coal and ash circuit consists of coal deli'er&" $re$aration of coal" handling of coal to the %oiler furnace" ash handling and ash storage. 5. "%at i* t%e $ain +'r+o*e o& t%e re*er1oirThe !ain $ur$ose of reser'oir is to store ater recei'ed fro! catch!ents areas during the rain& seasons and su$$l& the sa!e during the dr& season. 2. "%at i* t%e $ain +'r+o*e o& t%e ,a$The !ain $ur$ose of the da! is to increase the height of the or(ing head of the h&draulic $o er $lant. 3. "%4 tra*% ra)5 i* '*e,The trash rac( is used to $re'ent the entr& of de%ris" runners and choc( u$ the no))le of i!$ulse tur%ine. 6. "%at i* t%e '*e o& *'rge tan5The surge tan( is used to $ro'ide %etter regulation of ater $ressure in the s&ste!. The surge tan( controls the ater hen the load on the tur%ine decreases and su$$lies ater hen the load on the tur%ine increases. Thus" surge tan( controls the $ressure 'ariations resulting fro! the ra$id changes in ater flo in $enstoc( and hence $re'ents ater ha!!er. 7. "%at i* t%e &'n)tion o& 8ore 9a4hich !ight da!age the tur%ine ater le'el and also to increase
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Fore %a& is considered as naturall& $ro'ided surge tan(. It is te!$orar& ater storage hen the load on the $lant is reduced and $ro'ides ater for initial incre!ent on increasing load. #:. E;+lain a9o't +en*to)5The $i$e %et een surge tan( and $ri!e !o'er is (no n as $enstoc(. It is designed to ithstand high $ressure. It is !ade u$ of reinforced concrete. In 'er& cold areas" the $enstoc( is %uried to $re'ent ice for!ation and to reduce the e+$ansion ,oints. ##. "%at i* t%e '*e o& *+ill "a4*-$ill a& is li(e a safet& 'al'e of the da!. It discharges !a,or flood da!. It (ee$s the reser'oir le'el %elo the !a+i!u! le'el allo ed. #2. "rite a9o't +ri$e $o1er*.ri!e !o'er con'erts the (inetic energ& of ater into !echanical energ& to $roduce electrical energ&. .elton heel" tur%ine" Francis tur%ine" /a$lan tur%ine and .ro$eller tur%ine are $ri!e !o'ers used in h&draulic $o er $lants. #.. "%at are t%e '*e* o& air &ilter an, *'+er)%arger* in ,ie*el engine +ower +lantThe $ur$ose of air filter is to filter the air fro! dust and other sus$ended $articles. The $ur$ose of su$er charger is to increase the $ressure of the engine to increase $o er of the engine. #/. "%at i* t%e '*e o& ,ra&t t'9eThe draft tu%e is used to regain the (inetic energ& of ater co!ing out of reaction tur%ine. It ena%les the reaction tur%ine to %e $laced o'er tailrace le'el. #5. "%at i* t%e &'n)tion-o& )ooling *4*te$ in !ie*el +ower +lantThe function of cooling s&ste! is to re!o'e heat fro! the engine c&linder to (ee$ the te!$erature of the c&linder in lo range and e+tend engine life. #2. "%at )on*i*t* o& l'9ri)ation *4*te$ in ,ie*el engine +ower +lantThe lu%rication s&ste! consists of oil $u!$s" oil tan(s" filters" coolers and connecting $i$es. The $ur$ose of the lu%rication is to reduce the friction of !o'ing $arts and also $i$es to reduce the ear and tear of !o'ing $arts. #3. "%at i* t%e +'r+o*e o& inter)ooler in ga* t'r9ine +ower +lant-ince the $o er re0uired to co!$ress the air is less in isother!al $rocess it is re0uired to !aintain the" te!$erature of air constant as far as $ossi%le. 1ence the air lea'ing the 2... co!$ressor is cooled %& intercooler and then $assed to the 1.. co!$ressor. #6. Na$e two )o$9ine, +ower )4)le*• • Co!%ined c&cle of gas tur%ine and stea! $o er $lant. Co!%ined c&cle of gas tur%ine and diesel $o er $lant. ithout da!aging the
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#7. !e&ine t'r9o )%arging in )o$9ine, ga* t'r9ine an, ,ie*el )4)le*In the co!%ined c&cle" the e+haust gas fro! the diesel engine is e+$anded in the tur%ine" hich is cou$led ith co!$ressor hich su$$lies $ressuri)ed air to the diesel engine. This increases diesel engine out$ut. This arrange!ent is (no n as tur%o charging. 2:. "%at i* t%e $ain +'r+o*e o& %ig%-+re**'re 9oiler*The high#$ressure %oilers are used to increase the efficienc& of the $lant and to reduce the cost of electricit& $roduction. 2#. State i$+ortant a,1antage* o& %ig%-+re**'re 9oiler*• • The a!ount of scale for!ation is less" since the 'elocit& of ater through $i$es are !ore. All $arts of the s&ste! are heated unifor!l&" so there is no danger of o'erheating.
22. Na$e i$+ortant %ig% +re**'re 9oiler*• • • • 2a Mont %oiler Benson %oiler 2oeffler %oiler 4elo+ %oiler.
2.. "rite a9o't La Mont 9oiler- "%at i* t%e $a(or ,i*a,1antage o& La Mont 9oiler2a Mont %oiler is a forced circulation high $ressure ater tu%e %oiler. The !a,or disad'antage is the for!ation of %u%%les" salt and sedi!ent on the inner surfaces of the heating surfaces. This reduces the heat flo and stea! generation.
2/. "rite a9o't <en*on 9oiler- State *o$e i$+ortant a,1antage* o& <en*on 9oilerBenson %oiler is the high $ressure" 'ertical fire tu%e %oiler. This %oiler has no dru! and is 5designed to o$erate at critical $ressure of 336 %ar. Benson %oiler has no dru!. -o the total eight of the Benson %oiler is reduced %ź" hen co!$ared to other %oilers. o The erection of Benson %oiler is easier and 0uic(er. 25. "rite a9o't Loe&&ler 9oilerThe !a,or disad'antage in 2a Mont %oiler is the de$osition of salt and sedi!ent on the inner surface of the ater tu%es. It reduces the heat transfer and ulti!atel& the stea! generating ca$acit&. In 2oeffler %oiler" this $ro%le! is sol'ed %& $re'enting ater fro! flo ing through the %oiler tu%es. The stea! is generated outside the tu%es. 22. E;+lain Re%eat )4)leIf the dr&ness fraction of stea! lea'ing the tur%ine is less than 7.99" then" corrosion and erosion of tur%ine %lades occur. To a'oid this situation" reheat is used.
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In the reheat c&cle" the e+$ansion of stea! ta(es $lace in one ;or< !ore#tur%ines. -tea! is e+$anded in the 1. tur%ine first" and then it is reheated. The reheated stea! is again e+$anded in. the 2. tur%ine. 23. "%at are t%e i$+ortant a,1antage* o& Re-%eating• • • • Due to reheating" net or( done increases 1eat su$$l& increases Ther!al efficienc& increases Due to reheating" the tur%ine e+it dr&ness fraction increases so !oisture decreases # so %lade erosion %eco!es !ini!u! # so life of the tur%ine ill %e increased.
26. Na$e ,i&&erent $et%o,* o& re%eating;a< Gas Reheating ;%< 2i'e # stea! reheating ;c< Co!%ined gas li'e stea! reheater. 27. !e&ine 9lee,ing in *tea$ +ower +lantAssu!e I (g of stea! is e+$anded in the tur%ine. Before co!$lete a!ount of stea! #is e+$anded" so!e a!ount of stea! ;! (g< is #e+tracted = E+tracting the stea! in the tur%ine %efore e+haust is called %leeding. This %led stea! is used to heat the feed ater. .:. E;+lain t%e ter$ RegenerationRegeneration !eans heating the feed ater %& stea! ta(en fro! the tur%ine. The stea! is e+hausted ;%led< fro! the tur%ine at se'eral locations %efore e+haust and is su$$lied to regenerator ;feed ater heater< to heat the feed ater. .#. State *o$e a,1antage* o& Regeneration )4)le• • • 1eat su$$lied to %oiler %eco!es reduced Ther!al efficienc& is increased since the a'erage te!$erature of heat addition to the c&cle is increased. Due to %leeding in the tur%ine" erosion of tur%ine due to !oisture is reduced.
.2. Na$e ,i&&erent $et%o,* '*e, to e;tra)t *tea$ &or %eating t%e &ee, water• • • • Direct contact heater Drain $u!$ !ethod All drains to hot ell Cascade s&ste!
... !e&ine t%e ter$ wa*te %eat re)o1er4>aste heat is the heat hich is not at all used and e+hausted out as a aste $roduct. >aste heat is nor!all& a'aila%le fro! the industr& in the for! of $rocess stea! and ater at high te!$erature. Also" the aste heat is discharged ith the e+haust gases in so !an& industries. This heat can %e reco'ered for useful $ur$ose. This $rocess is (no n#as aste heat reco'er&. ./. "%at are t%e wa*te $aterial*= w%i)% )an 9e '*e, &or &'el &or +ower generation-
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• Munici$al aste • Industrial aste • .a$er aste • Ru%%er aste. .5 "rite a9o't wa*te %eat 9oiler*The aste heat %oilers use the aste heat in gases co!ing out of diesel engines and gas tur%ines at high te!$erature ;or< use the aste as a fuel in the incineration. -o!e %oilers use the industrial dirt& gases for $o er generation. .2. "rite a9o't &l'i,i*e, 9e, 9oiler*>hen the high 'elocit& gas is $assed through a $ac(ed %ed of finel& di'ided solid $articles" the $articles %eco!e sus$ended in the gas strea! and the $ac(ed %ed %eco!es a fluidised %ed. >hen the gas 'elocit& is 'er& high" the fluidised %ed %eco!e tur%ulent and ra$id !i+ing of $articles occurs. @lti!atel&" the" %eha'iour of !i+ture solid $articles and #gas %eco!e a fluid. Burning of a fuel in such a state is (no n as Fluidised Bed Co!%ustion. The %oiler $lant using this fluidised %ed co!%ustion is (no n as fluidised %ed %oilers. .3. State *o$e a,1antage* o& &l'i,i*e, 9e, 9oiler*• • • • An& t&$e of fuel # solid" li0uid ;or< gaseous fuel ;or< do!estic and industrial aste can %e used in FBC s&ste!. An& t&$e# of co!%usti%le !atter can %e %urned %& ad,usting the factors as si)e" air 'elocit& and rate of feed. 1igh heat transfer rate is $ossi%le to the surfaces i!!ersed in the %ed" %ecause solid !i+ing is e+tre!el& $ossi%le. 1igh co!%ustion efficienc&. The solid fuel need not %e $ul'erised in fluidised %ed %oilers.
.6. Na$e t%e two t4+e* o& )oal %an,ling• • Out $lant handling In#$lant handling.
.7. "rite a9o't o't-+lant %an,lingOut $lant handling includes the handling of coal!ine to the ther!al $o er $lant. These handlings are outside the $lant in the follo ing a&s. • Trans$ortation %& sea ;or< ri'er • Trans$ortation %& rail • Trans$ortation %& road • Trans$ortation of coal %& $i$eline. /:. "rite a9o't in+lant %an,ling o&-)oalIn order to handle large 0uantit& of coal inside the $lant" so!e !echanical handling s&ste!s are $ro'ided fAr s!ooth" eas& and %etter controlled o$eration. The in$lant coal handling is di'ided" into follo ing categories. • Coal unloading • Coal $re$aration • Coal transfer • Coal storage
A
/#. "%4 t%e +re+aration o& )oal i* ne)e**ar4The coal fro! coal nines cannot %e directl& fed into the furnace. .ro$er $re$aration of coal should %e done %efore feeding the coal to the furnace. In the coal $re$aration" the coal $asses through the different e0ui$!ents li(e *. Crushers 3. -i)ers :. Driers and Magnetic -e$arators. /2. Na$e t%e ,i&&erent t4+e* o& )oal tran*&or$ing e>'i+$ent**. Belt con'e&ors 3. -cre con'e&ors :. Buc(et ele'ators ?. Gra% %uc(et ele'ators 6. -(i$ hoists A. Flight con'e&ors. The coal transfer starts %& carr&ing of coal fro!#unloading $oint to the storage site. /.. "%at i* t%e '*e o& 9elt )on1e4or*Belt con'e&ors are !ostl& used for trans$orting coal o'er long distance ith large 0uantit&. An endless %elt is !ade to run o'er a $air of end dru!s and $ulle&s and su$$orted %& series of roller at regular inter'als. //. "rite a9o't *)rew )on1e4or an, 9')5et )on1e4or*In scre con'e&or" an endless helicoid scre is fitted to the Bhaft. On one end of the shaft" the dri'ing !echanis! is fitted and the other end of the shaft is su$$orted on a %all %earing. >hile the scre is rotating" the coal is transferredC fro! one end to the other end. Buc(et con'e&ors are used as 'ertical lifts. The coal is loaded at the %otto! and unloaded at the to$ in the %uc(et con'e&ors. /5. !e&ine ,ra'g%t= w%at i* t%e '*e o& ,ra'g%t in t%er$al +ower +lant*Draught is defined as a s!all $ressure difference re0uired %et een the fuel %ed ;furnace< and outside air to !aintain constant flo of air and to discharge the gases through chi!ne& to the at!os$here. Draught can %e o%tained %& chi!ne&" fan" stea! ,et ;or< #air ,et ;or< co!%ination of these. The uses are • To su$$l& re0uired 0uantit& of air to the furnace for co!%ustion of fuel. • To dra the co!%ustion $roducts through the s&ste!. • To re!o'e %urnt $roducts fro! the s&ste! /2. "rite a9o't )la**i&i)ation o& ,ra'g%tDraught is classified as *. Natural draught 3. Artificial draught The artificial draught is further classified as ;a< -tea! ,et draught ;%< Mechanical draught ;c< Induced draught ;d< Forced draught /3. !e&ine t%e ter$ Nat'ral ,ra'g%t an, w%at are t%e a,1antage* o& nat'ral ,ra'g%t *4*te$-
D
The tall chi!ne& creates the natural draught %& the te!$erature difference %et een hot gases in the chi!ne& and cold at!os$heric air outside the chi!ne&. The ad'antages are • No e+ternal $o er is re0uired • Air $ollution is less since gases are discharged at high le'el. • No !aintenance cost • Ca$ital cost is less than artificial draught. /6. "rite a9o't arti&i)ial ,ra'g%tIn !ode! $o er $lants" the draught should %e fle+i%le to !eet the fluctuating loads and it should %e inde$endent of at!os$heric conditions. To achie'e this" the aid of draft fans %eco!es !ust and %& e!$lo&ing the draft fans" the height of the chi!ne& ould %e reduced. /7. "rite a9o't &or)e, ,ra'g%t *4*te$In this s&ste!" the %lo er ;forced draft fan< is located at the %ase of the %oiler near the grate. Air is forced to the furnace %& forced fan and the flue gases are forced to chi!ne& through econo!iser and air $reheater. 5:. "%at are t%e a,1antage* o& &or)e, ,ra'g%t *4*te$ • • • -ince the fan handles cold air" the fan si)e and the $o er re0uired are less. No need of ater cooled %earings %ecause the air %eing handled is cold air" .ressure throughout the s&ste! is a%o'e at!os$heric $ressure so the air lea(age into the furnace is reduced.
5#. How t%e in,')e, ,ra'g%t i* wor5ingIn an induced draught s&ste!" a %lo er ;induced draft fan< is $laced near ;or< at the %ase of the chi!ne&. The fan suc(s the flue gas fro! the furnace creating a $artial 'acuu! inside the furnace. Thus at!os$heric air is induced to flo through the furnace to aid the co!%ustion of fuel. The flue gases dra n %& the fan $asses through chi!ne&" to the at!os$here. 52. "%4 t%e 9alan)e, ,ra'g%t *4*te$ i* +re&erre, t%an ot%er *4*te$In the induced draught s&ste!" hen the furnace is o$ened for firing" the cold air enters the furnace and dilate the co!%ustion. In the forced draught s&ste!" hen the furnace is o$ened for firing" the high $ressure air ill tr& to %lo out suddenl& and furnace !a& sto$. 1ence the furnace cannot %e o$ened for firing ;0< ins$ection in %oth" s&ste!s. Balanced draught" hich is a co!%ination of induced and forced draught" is used to o'erco!e the a%o'e stated difficulties. 5.. "%at i* t%e ,i&&eren)e 9etween *to)5er &iring an, +'l1eri*e, &'el &iringThe stoc(er firing !ethod is used for firing solid coal here as $ul'erised firing !ethod is used for firing $ul'erised coal. 5/. "%at are-t%e ,i&&erent t4+e* o& *to)5er**. O'er feed stoc(ers Tra'elling grate stoc(ers -$read stoc(ers 3. @nder feed stoc(ers -ingle retort stoc(er Multi retort stoc(er
9
55. "%at i* t%e '*e o& +'l1eri*er an, na$e ,i&&erent t4+e* o& +'l1eri*ing $ill*The $ul'eriser is used to $ul'erise the coal in order to increase the surface e+$osure. .ul'erised coal ena%les ra$id co!%ustion. The different t&$es of $ul'erising !ills are *. Ball !ill 3. 1a!!er !ill :. Ball and race !ill. 52. Na$e t%e two $et%o,* o& +'l1eri*e, &'el &iring *4*te$*. @nit ;or< direct s&ste! 3. Bin ;or< central s&ste!. 53. "%at are a,1antage* o& 'nit ?or@ ,ire)t *4*te$ o& +'l1eri*e, &'el &iring*. The la&out is si!$le and econo!ical 3. It gi'es direct control of co!%ustion :. Coal trans$ortation s&ste! is si!$le ?. Maintenance cost is less 56. How t%e a*% %an,ling *4*te$ i* )la**i&ie,*. Mechanical handling s&ste! 3. 1&draulic s&ste! :. .neu!atic s&ste! ?. -tea! ,et s&ste! 57. "%4 a*% %an,ling *4*te$ i*A nee,e,• • • To re!o'e the ashes fro! the furnace ash ho$$er To trans$ort the ashes fro! furnace ash # ho$$er to a storage To dis$ose the ashes fro! the storage
2:. Na$e ,i&&erent t4+e* o& ,'*t )olle)tor**. Mechanical Dust collector Gra'itational se$arators Bag house dust collector There are three t&$es of %ag house dust collector • O$en $ressure t&$e • Closed $ressure t&$e • Closed suction t&$e 3. C&clone. -e$arators :. Elector -tatic .reci$itator ;E-.< 2#. "%at i* t%e $ain +'r+o*e o& )%i$ne4The !ain $ur$ose of chi!ne& is to e!it the flue gases at a considera%le height to a'oid nuisance to the surrounding $eo$le. 22. "%at are t%e ,i&&erent t4+e* o& loa, a)t on t%e )%i$ne4There are t o t&$es of loads acting on the chi!ne& na!el&.
B
• • Its o n eight hich is considered to as a single 'ertical force acting through the centroid" and The >ind $ressure" hich is considered as the hori)ontal force acting on the centroid of 'ertical $ro,ected area.
2.. Na$e ,i&&erent t4+e* o& )%i$ne4*. -teel chi!ne& 3. -ite constructed chi!ne& :. .lastic chi!ne& 2/. !e&ine &or)e, ,ra&t an, in,')e, ,ra&t )ooling tower*
If the fan is located at the %otto! of the to er and air is %lo n %& the fan u$ through the descending ater it is called as forced draft cooling to ers If the fan is located at the to$ of the to er and air enters through the lou'ers located on the to erEs side and dra n u$ and discharge through the fan casing" it is called as induced draft. 25. "%at are t%e a,1antage* o& in,')e, ,ra&t )ooling tower o1er &or)e, ,ra&t )ooling toweri. The outlet ater co!es in contact ith the driest air and ar!est ater co!es in contact ith !ost hu!id air. ii. The re#circulation is seldo! a $ro%le!. iii. The first cost is lo due to the reduction in $u!$ $o er consu!$tion. 22. "%at are t%e a,1antage* o& %4+er9oli) nat'ral-,ra&t )ooling tower*• • • • -ince no fans are used $o er cost and au+iliar& e0ui$!ents cost is reduced. 1&$er%olic to er chi!ne& creates its o n draft e'en hen there is no ind Ground fogging and ar! air re#circulation are a'oided in h&$er%olic to ers The structure is !ore or less self#su$$orted.
23. "%at are t%e &a)tor* t%at a&&e)t t%e rate o& e1a+oration o& water in )ooling tower*• • • • • A!ount of ater surface area e+$osed The ti!e of e+$osure The relati'e 'elocit& of air $assing o'er the dro$lets The R1 of air The direction of airflo relati'e to ater.
26. "%at i* t%e wor5ing +rin)i+le o& Cooling Tower*The hot ater is s$ra&ed fro! the to$ of the to er" hile the air is !ade to flo fro! the %otto! of the to er to the to$. This air cools the hot ater in the cooling to er. Air 'a$orises a s!all $ercentage of ater" there %& cooling the re!aining ater. The air a%sor%s the heat and lea'es at the to$ of the to er and cooled ater lea'es at the %otto! and recirculated to the condenser.
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27. Na$e ,i&&erent t4+e* o& )ooling tower*The cooling to ers are classified as follo s. ;a< According to the construction of !aterial *. Ti!%er # for s!all to er 3. Ferro concrete # for large ca$acit& stations. :. Multi dec( concrete to ers # for large stea! stations ?. Metallic ;%< According to the nature of air draught# *. At!os$heric ;or< Natural draught cooling s&ste! 3. Mechanical draught cooling to er. 3:. How t%e at$o*+%eri) ?or@ nat'ral ,ra'g%t )ooling tower*- are )la**i&ie,In at!os$heric ;or< natural cooling to ers" the natural air $ro'ides the re0uired cooling ithout the use of fans. This is classified into three t&$es. *. Natural draft s$ra& filled to ers 3. Natural draft $ac(ed t&$e to ers.= :. 1&$er%olic cooling to ers 3#. How $e)%ani)al ,ra&t )ooling tower* are )la**i&ie,Mechanical draft cooling to er is classified into three t&$es *. Forced draft to er. 3. Induced draft counter flo to er :. Induced draft cross flo to er. 32. How t%e ,r4 t4+e )ooling tower* are )la**i&ie,The dr& t&$e cooling to ers are classified into t o t&$es =as follo s. *. Indirect dr& t&$e ;or< 1eller cooling s&ste! 3. Direct dr& t&$e#cooling s&ste! 3.. "%at are t%e $et%o,* to re,')e t%e e&&e)t* o& +arti)'late*The effects of $articulates can %e reduced %& the follo ing !ethods. • Coal cleaning • @sing i!$ro'ed electrostatic $reci$itator design • Controlling the dust ithin allo a%le li!it. This can %e done %& increasing the height of chi!ne& there%& reducing the concentration 3/. "%at are t%e e>'i+$ent* '*e, &or a*% )olle)tion• • • • Electrostatic $reci$itator Fl& ash scru%%ers Cinder catcher C&clone dust collector
35. "%at i* $eant 94 A!e*'l+%'ri*ationA an, na$e t%e $et%o,* a,o+te, &or ,e*'l+%'ri*ation-
**
Desul$hurisation of fuel is the $rocess of reducing the sul$hur content in the fuel. The follo ing !ethods are ado$ted for desul$hurisation. *. Che!ical treat!ent 3. Forth flotation :. Magnetic se$aration 32. "%at are t%e $et%o,* a,o+te, to re$o1eA S:2 &l'e ga*e**. >et scru%%ing 3. -olid a%sor%ent :. Catal&tic o+idation 33. "rite a9o't C:2 re)or,er*In ther!al $o er $lants" it is necessar& to (ee$ the concentration Of C73 as lo is necessar& as $ossi%le. To achie'e this" a constant recording of concentration Of C73 These recorders are %ased on the three different $rinci$les" as gi'en %elo . *. Ther!al conducti'it& cell 3. Che!ical a%sor$tion cell :. Densit& %alance B3. >hat is the# necessit& of Auto!atic controls for feed aterF The electrical load on $o er $lant 'aries in an irregular !anner. The auto!atic control $ro'ided at a stea! $o er $lant successfull& !eets o'er the 'aria%le load. The auto!atic control for feed ater is necessar& sine the su$$l& of feed ater de$ends u$on $lant load. 36. Na$e *o$e o& t%e a'to$ati) )ontrolling $et%o,* &or &ee, water*. -ingle ele!ent $ilot o$erated s&ste! 3. -ingle ele!ent self o$erated s&ste! :. T o ele!ent $ilot o$erated s&ste! ?. Three ele!ent $ilot o$erated s&ste! 37. "%at i* t%e +'r+o*e o& a'to$ati)= )o$9'*tion )2#ritrolThe !ain $ur$ose of #auto!atic co!%ustion= control s&ste! is to !aintain load against de!and" to $re'ent s!o(e" to increase %oiler house efficienc&" to carr& out routine ad,ust!ents and to $ro'ide interloc(ing safe guards. 6:. "%at are t%e a++lian)e* 5nown a* 9oiler a))e**orie*The a$$liances used to increase the efficienc& of the %oiler are (no n as %oiler accessories. The i!$ortant %oiler accessories are *. Econo!iser 3. -u$erheater :. Air $reheater ?. Feed $u!$ 6. In,ector 6#. "%at are t%e $et%o,* a,o+te, to re$o1e SO 2 &ro$ ,'e ga*e**. >et scru%%ing 3. -olid a%sor%ent :. Catal&tic o+idation 62. "rite a9o't C:2 re)or,er*In ther!al $o er $lants" it is necessar&" to (ee$ the concentration of C73 as lo as $ossi%le. To achie'e this = a constant recording of concentration of C73 is necessar&.
*3
These recorders are %ased on the three different $rinci$les" as gi'en %elo . *. Ther!al conducti'it& cell 3. Che!ical a%sor$tion cell :. Densit&# %alance 6.. "%at i* t%e ne)e**it4 o& A'to$ati) )ontrol* &or &ee, waterThe electrical load on $o er $lant 'aries irregular !anner. The auto!atic !an control $ro'ided at a stea! $o er $lant successfull& !eets o'er the 'aria%le load. The auto!atic control for feed ater is necessar& sine the su$$l& of feed ater de$ends u$on $lant load. 6/. Na$e *o$e o& t%e a'to$ati) )ontrolling $et%o,* &or &ee, water• • • • A single ele!ent $ilot o$erated s&ste! -ingle ele!ent self o$erated s&ste! T o ele!ent $ilot o$erated s&ste! Three ele!ent $ilot o$erated s&ste!
65. "%at i* t%e +'r+o*e o& a'to$ati) )o$9'*tion )ontrolThe !ain $ur$ose auto!atic co!%ustion control s&ste! is to !aintain load ad,ust de!and" to $re'ent s!o(e" to increase %oiler house efficienc&" to carr& out routine ad,ust!ents and to $ro'ide interloc(ing safe guards. 62 "%at i* t%e '*e o& air +re%eaterAir $re heater is used to transfer heat fro! the flue gases to the air %efore it $asses into the furnace for co!%ustion. It is $laced %et een the econo!i)er and chi!ne&. The o'erall efficienc& of the $lant !a& %e increased %& *7 $er cent %& the use of air $reheater. 63. "rite a9o't 9oiler $o'nting*The de'ices used for the efficient o$eration" $ro$er !aintenance" and safe o$eration %oiler !ountings. The different %oiler !ountings are *. >ater gauge ;or< ater le'el indicator 3. .ressure gauge ;or< stea! gauge :. -afet& 'al'es ?. Fusi%le $lug 6. -to$ 'al'e A. Blo off coc( D. Feed chec( 'al'e. 66. "%at i* $eant 94 9oiler trial-tea! is generated in %oilers under certain conditions of feed ater and e+ists as stea! hile a certain a!ount of fuel is %urnt. To stud& the $erfor!ance of %oiler" so!e e+$eri!ents are conducted %& o$erating" the %oiler for a certain length of ti!e and recording the data. This $rocedure is (no n as %oiler trial. 67. State t%e o9(e)ti1e o& 9oiler trial*.To deter!ine the ther!al efficienc& of the %oiler hen or(ing at a definite $ressure. 3.To dra u$ heat %alance sheet for the %oiler to chec( the $erfor!ance of the %oiler.
*:
7:. !e&ine ,e$an, &a)tor• • • De!and factor is defined as the ratio of !a+i!u! de!and to connected load. Connected load is the su! of ratings in (> of e0ui$!ent installed in the consu!er=s $re!ises. Ma+i!u! de!and is the !a+i!u! load" hich a consu!er uses at an& ti!e.
7#. !e&ine loa, )'r1e2oad cur'e is a gra$hical re$resentation %et een load in (> and ti!e in hours. It. sho s 'ariatiAn of load at the $o er station. The area under the load cur'e #re$resents the energ& generated in a $articular $eriod. 72. !e&ine loa, &a)tor2oad factor is defined as the ratio of a'erage load to the $ea( load ;or< !a+i!u! de!and. 7.. "%at in)l',e* &i;e, )o*tFi+ed cost includes the follo ing cost. *. Cost of land 3. Cost of %uilding :. Cost of e0ui$!ent ?. Cost of installatiAn 6. Interest A. De$reciation cost D. Insurance 9. Manage!ent cost 7/. "%at in)l',e* o+erating )o*tO$erating cost includes the follo ing cost. *. Cost of fuel 3. Cost of o$erating la%our" :. Cost of !aintenance la%ours and !aterials. ?. Cost of su$$lier li(e >ater for feeding %oilers" for condenser and for general use. 2u%rication oil and" grease. >ater treat!ent che!icals. 75. "%at i* t%e nee, o& ,e+re)iation )o*tDe$reciation cost is the a!ount to %e set aside $er &ear fro! the inco!e of the $lant to !eet the de$reciation caused %& the age of ser'ice" ear and tear of the !achiner& and e0ui$!ents. De$reciation a!ount collected e'er& &ear hel$s in re$lacing and re$airing the e0ui$!ent. 72. "rite a9o't ato$i) n'$9erThe nucleus contains $rotons and neutrons. The nu!%er of $rotons in a gi'en ato! is an ato!ic nu!%er ;G<. The ato!ic nu!%er for 1 is * and 1e #is 3. 73. "rite a9o't i*oto+e* o& an ele$ent-o!e ele!ents ha'e the sa!e nu!%er of $rotons in the nucleus %ut different nu!%er# of neutrons. As a result" these ele!ents ha'e the sa!e ato!ic nu!%er %ut different !ass nu!%er. -uch t&$e of ele!ents hich = ha'e the sa!e ato!ic nu!%er H sa!e nu!%er of $rotons # the #sa!e che!ical $ro$erties %ut different !ass nu!%ers due to different nu!%er of neutrons" are (no n as I the isoto$es of an ele!ent.
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76. "%at are t%e re>'ire$ent* to *'*tain &i**ion +ro)e**• • • • The %o!%arded neutrons !ust ha'e sufficient energ& to cause fission The nu!%er of neutrons $roduced !ust %e a%le to create the rate of fission The fission $rocess !ust generate energ& The fission $rocess !ust %e controlled
77. !e&ine $'lti+li)ation &a)tor o& a &i**ion +ro)e**. nu!%er of neutrons of an& one generation (I nu!%er of neutrons of i!!ediatel& $receding generation. #::. !e&ine &ertile $aterial* an, 9ree,ing in rea)tor* There are !aterials li(e @3:6 and Th3:3 hich are not fissile %ut can %e con'erted into fissile !aterials %& the %o!%ard!ent of neutrons. -uch !aterials are (no n as fertile !aterials. The $rocess of con'erting !ore fertile !aterial into fissile !aterial in a reaction is (no n as %reeding. #:#. "%at are t%e ,e*ira9le +ro+ertie* o& a goo, $o,erator• It !ust %e as light as $ossi%leIt !ust slo do n the neutron as 0uic( as $ossi%le • It !ust ha'e resistance to corrosion • It !ust ha'e good !achina%ilit& • It !ust ha'e good conducti'it& and high !elting $oint #:2. "%at are t%e ,e*ira9le +ro+ertie* o& a )oolant• It should not a%sor% neutron • 1a'e high che!ical and radiation sta%ilit& • Non#corrosi'e • 1a'e high %oiling $oint • Non#to+ic #:.. Na$e &ew t4+e* o& rea)tor*. Fast reactors" Ther!al reactors" natural fuel reactors" Enriched @raniu! reactors" ater !oderated reactors" hea'& ater !oderated reactor" gra$hite !oderated reactor" gas cooled reactors and -odiu! cooled reactors. #:/. "%at are t%e a,1antage* '*ing CO2 a* )oolant• Gases do not react che!icall& ith the structural !aterials • Gas can attain an& te!$erature for a $articular $ressure • The& do not a%sor% neutron • The lea(age of gas ill not affect the reacti'it& • The gas coolant $ro'ides %est neutron econo!& #:5. "%at are t%e a,1antage* o& 9ree,er rea)tor*• It gi'es high $o er densit& than an& other reactor • 1igh %reeding is $ossi%le • 1igh %urn#u$ of fuel is achie'a%le
*6
• The o$eration of the reactor is not li!ited %& Xe $oisoning
#:2. "%at are t%e ,e$erit* o& 9ree,er rea)tor• 1ighl& enriched fuel is re0uired • Control is difficult and e+$ensi'e • -afet& !ust %e $ro'ided against !elt do n • 1andling of sodiu! is a !a,or $ro%le! #:3. "%at are t%e a,1antage* o& So,i'$ in &a*t-9ree,er rea)tor*• -odiu! has 'er& lo a%sor$tion cross#sectional area • It $osses good heat transfer $ro$erties at high te!$erature and lo $ressure • It does not react ith an& of the structural !aterials used in $ri!ar& circuits #:6. Na$e t%e ,i&&erent t4+e* o& MH! generator* • O$en c&cle M1D • Closed c&cle M1D • Closed c&cle M1D ith li0uid !etal #:7. "%at i* t%e wor5ing +rin)i+le o& $agneto %4,ro,4na$i) +ower +lantThe or(ing $rinci$le of M1D is as li(e that of d&na!o. Instead of solid conductor high te!$erature $las!a is $assed through the !agnetic field at sonic s$eed. >hen the gas is $assed through !agnetic field" current is induced. Electrodes collect this induced current. ##:. "%at i* t%e +'r+o*e o& )ontrol ro,*The control rods are used to start the chain reaction" !aintain the chain reaction at re0uired le'el and to shut do n the reactor during e!ergenc&. ###. "%at are t%e ,i&&erent t4+e* o& loa, a)ting on t%e )%i$ne4• Its o n eight hich is considered to act on a single 'ertical force acting through the centroid • The ind $ressure" hich is considered to act on the hori)ontal force acting on the centroid of 'ertical $ro,ected area.
##2. "%at i* $eant 94 N')lear &i**ion@raniu! e+ists in different isoto$es of @3:9" t.:? and @3:6. Out of these" E.:6 is !ost unsta%le. >hen unsta%le hea'& nucleus is %o!%arded ith high#energ& neutrons" it s$lits u$ roughl& into t o e0ual frag!ents and a%out 3.6 neutrons are released and a large a!ount of energ& is $roduced. This $rocess is called nuclear fission. ##.. Na$e t%e ,i&&erent )o$+onent* o& n')lear rea)tor*. Nuclear fuel 3. Moderator :. Control rods ?. Reflectors 6. Reactor 'essel A. Biological shielding D. Coolant ##/. • • State *o$e a,1antage* o& Pre**'riBe, "ater rea)torThe $ressuri)ed ater reactor is co!$act In this t&$e" ater is used as coolant" !oderator and reflector ater is a'aila%le in $lent&< • It re0uires less nu!%er of control rods. ##5. "%at are t%e a,1antage* o& ga* )oole, rea)tor n')lear +ower +lant-
chea$
and
*A
*. Fuel $rocessing is si!$le 3. The use of C73 as coolant co!$letel& eli!inates the $ossi%ilit& of e+$losion in reactor. :. No corrosion $ro%le! ##2. "%at i* 9ree,ing in n')lear rea)torThe $rocess of $roducing fissiona%le !aterial fro! a fertile !aterial such as uraniu! 3:9 ;@3:9< and thoriu! 3:3 ;Th 3:3 < %& neutron a%sor$tion is (no n as %reeding. ##3. Na$e t%e )oolant* )o$$onl4 '*e, &or &a*t 9ree,er rea)tor*2i0uid !etal ;Na ;or< Na /< 1eliu! ;1e< Car%on dio+ide.
