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TRUNG TM TH NGHIM IN

CCH TNH HIU SUT V CC GII PHPNNG CAO HIU SUT L HI CNG SUT NH

H ni, nm 2007


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http://www.ebook.edu.vn 2

NI DUNG:

Phn I: Cc phng php tnh hiu sut l hi .......................... Trang 3

1. Phng php tnh hiu sut l theo cn bng nghch ......... Trang 31.1 L hi t than .................................................................... Trang 31.1.1 Tn tht nhit q4 ............................................................ Trang 41.1.2 Tn tht nhit q2 .......................................................... Trang 41.1.3 Tn tht nhit q5 ........................................................... Trang 51.1.4 Tn tht nhit q6 ........................................................... Trang 61.1.5 Tn tht nhit q3 .......................................................... Trang 61.1.6 Tiu hao nhin liu ca l .............................................. Trang 61.2 L hi t du .................................................................... Trang 61.2.1 Tn tht nhit q

2................................................................ Trang 7

1.2.2 Tn tht nhit q3 ................................................................. Trang 81.2.3 Tn tht nhit q5 ................................................................. Trang 82. Phng php tnh hiu sut l theo cn bng thun ................ Trang 82.1 L hi t du ...................................................................... Trang 92.2 L hi t than ................................................................... Trang 10

Phn II: Nhin liu v c tnh ca nhin liu ............................ Trang 111. c tnh ca nhin liu rn v lng ....................................... Trang 112.Tnh th tch khng kh v khi khit nhin liu rn v lng .......................................................... Trang 123. c tnh nhin liu kh............................................................ Trang 14

Phn III: Cc yu tnh hng n hiu sut l v ccbin php nng cao hiu sut l hi ................................................. Trang 17

1. nh hng ca thit b ln hiu sut lv bin php khc phc .......................................................... Trang 172. nh hng ca ch vn hnh l ln hiu sut ca l ........ Trang 183. Th nghim nng hiu sut, xc lpch vn hnh ti u cho l....................................................... Trang 193.1 Th nghim phn phi gi ti u ......................................... Trang 193.2 Th nghim xc nh h s khng kh tha ti u ................ Trang 203.3 Th nghim cn bng nhit, lpbng ch vn hnh ti u ...................................................... Trang 21

Phn IV: Cc i lng chnh cn phi o lng trong thnghim hiu chnh l hi v mt s thit b phc v th nghim......Trang 23


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q2 l tn tht nhit ca l theo khi thi. Tn tht ny ln hay nh lty thuc vo nhit khi thot, h s khng kh tha, lt gi vo l.q3l tn tht nhit do chy khng hon ton v mt ha hc. Tn thtny chng k khi l thiu gi, hoc thiu gi cc b. Tn tht ny s

khng ng k khi l gi.q4 l tn tht nhit v mt chc. Tn tht ny thng l ln nht - ivi l hi t than ph thuc vo lng cht chy (C) cha ht cn litrong tro bay v x l.q5 - l tn tht nhit t l ra mi trng xung quanh. Tn tht ny phthuc vo cng sut l (l ln hay b) v tnh trng bo n ca l tt hayxu.q6 l tn tht nhit vt l theo x. Tn tht ny thng rt nh, n chng k khi tro ca than rt ln v nhit x thi ra ln. Trong thct vi l hi cng sut nh ta c th b qua tn tht ny.Di y chng ti s trnh by ln lt phng php xc nh cc tntht trn.

1.1.1 Tn tht nhit v chc q4c tnh theo cng thc:q4 = lv

t

lv

Q

A.7830 (abt

t

C

C

100+ ax

x

x

C

C

100) % (1.1-2)

Trong :

Alv

- tro lm vic ca than (%)Qtlv - Nhit tr thp lm vic ca nhin liu (kcal/kg)

ab - T l tro bay theo khi.i vi l than phun : ab = 0,9 ; ax = 0,1i vi l ghi : ab = 0,2 ; ax = 0,8.

Vi l hi t than cng sut nh ch yu l l ghi hoc ghi xch.Ct - Hm lng cacbon cn li trong tro bay (%).Cx - Hm lng cc bon cn li trong x (%).

1.1.2 Tn tht nhit theo khi thi q2 tnh theo cng thc:q2 = (Ikt -kt.Iokkl) x (

4

4

100 qq

), %

(1.1-3)Vi: Ikt - Entanpi ca khi thot, tnh theo cng thc (2- 4).

kt - H s khng kh tha khi thot.Ikkl - Entanpi gi lnh vo l, tnh theo cng thc (2-3).

Trong trng hp khng phn tch c thnh phn ho hc ca than,m ch phn tch cng nghip, tn tht nhit q2 c th tnh theo cng thc gnng:


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( ) ( )%10100

112,0

38,0.53,3 242

++=

qttq gl

kt

ktktkt

(1.1-4)

Trong :kt - l h s khng kh tha khi thot ra khi l.tkt - l nhit khi thot ra khi l (oC)tgl- l nhit gi lnh vo l (

oC)

1.1.3 Tn tht nhit ra mi trng xung quanh q5c tnh:q5 = q5

m xqn

dm

D

D, % (1.1-5)

Vi: q5m - Ly theo thit kph ti nh mc hoc tra theo cng sut

l.

i vi l hi 2T/h: q5m = 3,2 %i vi l hi 4T/h: q5

m = 1,9 %

i vi l hi 6T/h: q5m = 1,5 %

i vi l hi 8T/h: q5m = 1,2 %

Dqn - c tnh theo lu lng hi quy dn khi th nghim o c.Dm - Sn lng hi nh mc ly theo thit k.

Ngoi ra q5 c th tnh theo cch khc chnh xc hn nu o c nhit trung bnh b mt l hi, nhit mi trng trung bnh xung quanh l hi.

Nhit b mt l hi phi c o vi s lng im o ln (mi imcch nhau khong 0,5 m). Nhit mi trng xung quanh l hi cng phic o nhiu im, cch xa ti thiu b mt l 1 m. Khi cng thc tnh q5s l:

q5 = 100. 0,86 . (Hl + Hbx) . Fbm . (Tbm - Tmt)/(B.lv

tQ ), % (1.1-6)

Trong cng thc (1-6):Tbm l nhit trung bnh b mt l hi (

oC).Tmt l nhit mi trng xung quanh l hi (

oC).

B l tiu hao nhin liu ca l hi (kg/h hoc T /h)Fbm l tng din tch b mt ngoi ca l hi (m

2)Hl l h s truyn nhit i lu c tnh nh sau:

Hl = 1,1354 . (Tbm - Tmt)(1/3) W/m2.oC (1.1-7)

Hbx = 5,677. {0,847 + 2,367.10(-3). (Tbm -Tmt) + 0,294. 10

(-6)(Tbm - Tmt)2

+ 1,37 . 10(-9) (Tbm - Tmt)3 W/m2.oC (1.1- 8)

Khi p dng cng thc ny do tiu hao nhin liu B cha bit nn ta phi

chp nhn ly B theo s liu thit k ri tnh lp i lp li cc tham s q5 , , Bkhong 3 ln t c chnh xc cn thit.


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1.1.4 Tn tht nhit mang theo x q6c tnh theo cng thc:q6 =

)100(

...

x

lv

t

xpxx

lv

CQ

tCaA

% (1.1-9)

Vi: Cpx - Nhit dung ring ca x.tx - Nhit ca x ri vo phu thi x.

i vi l ghi c th ly: xC = 0,933 kj/kg.oC, tx = 600

oC hoc o trctip.1.1.5 Tn tht nhit q3c tnh theo cng thc:

q3 =).(

..6,56

2 COROQ

COKlv

t

P

+, % (1.1-10)

Vi:CO, RO2 - % th tch cc kh CO, RO2 trong khi, c xc nh bng

my phn tch khi. RO2 l tng % th tch ca cc kh CO2 v SO2.CO - % th tch kh CO trong khi, khi phn tch bng my thng chota n v l ppm, mun bin i v % th tch phi chia cho 10000.Kp H s cacbon qui dn, sc cp phn sau.

Ngoi ra q3 cng c th tnh theo cng thc thc gn ng sau:

q3 = 3,2 . kt . CO (%) (1.1- 11)1.1.6 Tiu hao nhin liu ca l B c tnh theo cng thc:

B =lv

tQ.

)i-(i'.D)i-(i.D ncbhxncqnt

+, (T/h hoc kg /h) (1.1-12)

Vi:Dx- Lu lng nc x ca l, c th ly theo nh mc thit k. i vi

l hi cng sut nh c h thng x lin tc, Dx c th ly gn bng 1,5% n2% lu lng hi thc. i vi l hi cng sut nh khng c h thng x lintc, khi xc nh hiu sut l khng x cn c th coi Dx = 0.

i'bh- entanpi ca nc bo ho tra bng theo cc thng s p lc hocnhit ca hi.

iqn, inc - entanpi ca hi qu nhit v nc cp theo tra bng theo cc

thng s p lc, nhit ca hi v nc cp.Dt - Lu lng thc ca hi qu nhit (hoc bo ho nu l khng c bqu nhit). Lu lng hi thc c tnh nh sau:

Dt = D.(P/Ptk)(1/2)

Vi: D- lu lng hi c o bng ng h lu lng hi iu kin vnhnh, P - p lc hi iu kin vn hnh, Ptk- p lc hi iu kin thit k.

Trong trng hp l khng c ng ho lu lng, c th xc nh Dtca l theo lu lng nc cp, nhng khi phi tm dng x l.

1.2i vi l hi t du :Hiu sut l c tnh theo phng php cn bng nghch nh sau:


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= 100 - q2 - q3 - q5 , % (1.1-13)

1.2.1 q2 - Tn tht nhit do khi thi c tnh: fxff q2 =

dv

kt

Q

).-(I kklktI , % (1.1-14)

kt - H s khng kh tha khi thi.

- Ikkl - Entanpi ca khng kh lnh c tnh:Ikkl = Vkkl. Ckkl . Tkkl , kcal/kg (1.1-15)

Vi :

Vokkl- Th tch khng kh l thuyt cho t 1 kg nhin liu - cch tnhxem cng thc (2.2-5) .

Ckkl - Nhit dung ring ca khng kh lnh, tra bng theo cch sch k

thut nhit.Tkkl - Nhit khng kh lnh, o thc t ti hin trng.

- Ikt - Entanpi ca khi thi c tnh:Ikt = (CRO2VRO2+CN2VN2+CH2OVH2O).Tkt +(kt - 1).Vkkl. Ckk.Tkt (1.1-16)

Vi:

+ VRO2, VN2, VH2O - th tch cc kh RO2, N2, v hi nc trongkhi thot.

+ CRO2, CN2, CH2O - T nhit ca cc kh RO2, N2, v hi nctrong khi thot, nhit Tkt.

+ Tkt - Nhit khi thot.- Qdv - Lng nhit n va vo l c tnh:

Qdv = Qtlv + Cd. Td + gtd. itd +bl. (ikk- ikkl), kcal/kg. (1.1-17)

Vi:

Qtlv Nhit tr thp lm vic ca du, (kcal/kg) c xc nh theo

kt qu phn tch du.gtd T l hi tn du tnh bng kg.hi / kg.du, thng thng gtd

= 0, 1. Thng s ny ch tnh n khi vi phun du dng hi tn du tngun ngoi l hi.

itd- entanpi ca hi tn du, tra bng theo cc thng s nhit , plc hi tn du.

Td Nhit du vo l, sau b sy du, c o trc tip ti hintrng. Thng s ny cng ch tnh n khi s dng b sy du bng

ngun nhit ngoi l hi (v d nh s dng b sy du bng in).


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Cd Nhit dung ring ca du nhit Td , c tra theo cc tiliu k thut.

bl - c xc nh theo kt qu phn tch khi trc b sykhng kh.

ikk, ikkl - Entanpi khng kh sau v trc b sy khng kh sb,c tnh theo cng thc:

ikk= Ckk . Tkk kcal/m3 (1.1-18)

Vi: Ckk nhit dung ring ca khng kh nhit Tkk

Thng thng cc l hi t du cng sut ln v va, s dngcc b sy sb khng kh vo l bng ngun nhit ngoi l c thbng hi, in chng n mn phn ui l. Khi ta buc phi tnhn ikk v ikkl. Nhng a s cc l hi cng sut nh khng c b sy sb khng kh vo l nn ta khng cn tnh n cc thng s trn.

Tm li i vi cc l hi t du cng sut nh, hu ht khng sdng hi tn du v b sy khng kh sb, nn cng thc (2-5) ch cnn gin nh sau:

Qdv = Qtlv + Cd. Td, kcal/kg (1.1-19)

1.2.2 q3 - Tn tht nhit ho hc c tnh:q3 =

).(

..6,56

2 COROQ

COK

dv

P

+

, % (1.1- 20)

Vi: CO, RO2 - % th tch cc kh CO, RO2 trong khi thot.

Ngoi ra q3 cng c th tnh theo cng thc thc gn ng sau:

q3 = 3,2 . kt . CO (%)

1.2.3 Tn tht nhit q5 , ging nh l t than, c tnh theo cng thc(1.1-5) hoc (1.1-6).

2. Phng php tnh hiu sut l theo cn bng thun (u vo - u ra):Nh ni phn u, phng php xc nh hiu sut theo cn bng thun

ch thng p dng vi cc l hi c h thng o m y , chnh xccao, t nht l 0, 5. Cc ng ho sau nht thit phi c v phi t c chnh xc cn thit:

- ng ho lu lng hi hoc lu lng nc cp.- ng ho nhit hi, nhit nc cp.- Nhit khng kh vo l.-ng ho nhit nhin liu u vo (du, kh).- ng ho p lc hi.


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- ng ho lu lng nhin liu u vo (du, kh) hoc cn than uvo.

- Kt qu phn tch nhin liu phi tht chnh xc, nht l i vi nhittr.

- Lu lng nc x l.- Lu lng khng kh vo l.

Khi t c cc yu cu trn c th xc nh hiu sut l theo phng phpcn bng thun nh s trnh by di y.

2.1i vi l hi t du :Hiu sut l c tnh theo phng php cn bng thun nh sau:

=vlQ

Q1 x 100, % (1.1-21)

Trong :

Q1 - Tng lng nhit hu ch m l nhn c tnh theo:

Q1 = Dqn(iqn- inc) + Dx(inl- inc)+ Gtd(itd-inc) kcal/h (1.1-22)

Vi:

Dqn, Dx, Gtd - Lu lng hi qu nhit, lu lng nc x l, lulng hi tn du (kg/h). Ch Dqn - L lu lng hi thc ca l. Hi

tn du - Gtd c th bao gm c hi sy du nu hi sy du ly t l.iqn, inc, inl, itd - Entanpi ca hi qu nhit, nc cp, nc l v hi tndu.

Nu hi tn du, sy du ly theo ngun ngoi l hoc ly t ngun tbn ngoi l, khng c h thng x lin tc v trong thi gian th nghimkhng xnh k (x cn) th khng tnh n trong cng thc ny. Khi cng thc (2.1-2) c dng n gin nh sau:

Q1 = Dqn(iqn- inc) , kcal/h (1.1-23)

Qvl - Tng lng nhit a vo l tnh theo:Qvl = B. Qt

lv + Gkk(ikk- ikkl)+ Gtd. Itd+ B.Cd. Td, kcal/h (1.1-24)Vi:

B - Tiu hao du kg /h o theo bn hoc cng tdu (ch l d odu theo bn du hay theo cng tu phi c kim nh t chnhxc cn thit v c du ca cquan chc nng c thm quyn).

Qtlv - Nhit tr thp lm vic ca du.

Gkk- Lu lng gi qua b sy khng kh bng hi (m3/h).

ikk, ikkl - Entanpi khng kh sau v trc b sy khng kh bng hi.Cc thng s khc c cp phn trn.


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Cd Nhit dung ring ca du nhit Td , c tra theo cc tiliu k thut.

i vi cc l hi cng sut nh, c th khng c b sy khng kh sbly ngun nhit t bn ngoi, khng tn du bng hi ly ngun nhit t ngoil th cng thc (2.1-4) ch c dng n gin nh sau:

Qvl = B. Qtlv + Gkk.ikkl +B.Cd. Td, kcal/h (1.1-25)

2.2i vi l hi t than :V nguyn tc chung, tnh hiu sut l t than theo cn bng thun cng

ging vi l hi t du. Cng thc tnh hiu sut vn l:

=vlQ

Q1 x 100, % (1.1-26)

Trong :

Q1 - Tng lng nhit hu ch m l nhn c tnh theo:

Q1 = Dqn(iqn- inc) + Dx(inl- inc)+ Gtd(itd-inc) kcal/h (1.1-27)

Vi:

Dqn, Dx - Lu lng hi qu nhit, lu lng nc x l.

Gtd - y c hiu l hi t dng ca l, (kg/h).

iqn, inc, inl, itd - Entanpi ca hi qu nhit, nc cp, nc l v hi tdng.

Nu hi t dng ly ngun t bn ngoi l hoc khng c hi t dng,khng c h thng x lin tc v trong thi gian th nghim khng xnh k(x cn) th khng tnh n trong cng thc ny. Khi cng thc (2.2-2) cdng n gin nh sau:

Q1 = Dqn(iqn- inc) , kcal/h (1.1-28)

Qvl - Tng lng nhit a vo l tnh theo:

Qvl = B. Qtlv + Gkk. ikkl + B.Ct. Tt , kcal/h (1.1-29)Vi:

B - Tiu hao than kg /h tnh theo cn than in t (ch l cn thanphi c kim nh t chnh xc cn thit v c du ca cquanchc nng c thm quyn), hoc cn than th cng.

Qtlv - Nhit tr thp lm vic ca than.

Tt Nhit than vo l.

Ct Nhit dung ring ca than nhit Tt .

Gkk- Lu lng gi vo l (m3/h).


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ikkl - Entanpi khng kh trc b sy khng kh.

Cc thng s khc c cp phn trn.

Qua cch tnh hiu sut l theo cn bng thun va cp trn ta thyphng php ny gip cho ta tnh c hiu sut l, nhng khng cho ta thynguyn nhn gy ra tn tht nhit t c cc bin php gim cc tn thtnhit, nng cao hiu sut l hi. V vy phng php xc nh hiu sut theocn bng thun khng c khuyn khch dng nht l i vi cc l hi tthan.

PHN II: NHIN LIU V CC C TNH CA NHIN LIU.

xc nh c hiu sut l hi v tm cc bin php nng cao hiusut l hi, ta khng th khng quan tm n nhin liu dng cho l v cc ctnh ca n.

Nhin liu dng cho l hi c 3 dng chnh: rn, lng, kh.Nhin liu rn thng dng l cc loi than, ci, b ma.Nhin liu lng thng dng l du FO, du maztNhin liu kh thng dng l kh ho lng, kh thin nhin, kh cng

nghipDi y chng ti khng trnh by su vc tnh nhin liu m ch

trnh by mt sc tnh chnh ca nhin liu lin quan n vic th nghimxc nh hiu sut l tm cch nng cao hiu sut ca n.

1. c tnh nhin liu rn v lng:Thnh phn ho hc ca nhin liu rn v lng bao gm cc cht sau:

Cacbon k hiu l: C Hydro k hiu l: H Lu hunh k hiu l: S Nitk hiu l: N Oxy k hiu l: O tro k hiu l: A m k hiu l: W

Trong thc t khi em nhin liu i phn tch l trng thi lm vic,nn cc thnh phn trn cng c biu din trng thi lm vic. Chng tacng ch quan tm n trng thi lm vic ca nhin liu m thi. trng thilm vic, cc thnh phn trn c k hiu nh sau: Clv, Hlv, Slv, Nlv, Olv, Alv,Wlv .

Sau khi phn tch, chng ta s thu c kt qu nh sau:Clv + Hlv + Slv + Nlv + Olv + Alv + Wlv = 100 % (2.2-1)

Trong cc thnh phn trn, ch c Clv, Hlv, Slv, Olv l tham gia vo qu trnh

chy, to ra mt nhit lng iu kin thc t gi l nhit tr thp lm vic


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k hiu l Qtlv. Cc thnh phn cn li u khng li cho qu trnh chy. Tuy

nhin khi phn tch nhin liu ta phi phn tch tt c cc thnh phn trn.Cc c tnh cng ngh ca nhin liu:

Ngi ta coi cc thnh phn sau mang c tnh cng ngh:

m k hiu l W, %: m l lng nc n cha trong nhin liu.S c mt ca chng lm gim thnh phn chy, hn th na cn tiutn thm mt lng nhit bc hi m khi chy nhin liu. V vy nl thnh phn c hi trong nhin liu.

tro k hiu l A, %: tro l cc khong cht cn li sau khi chyht nhin liu. S c mt ca chng trong nhin liu lm mi mn, lmbm bn cc b mt chu nhit dn n gim h s truyn nhit. Hn thna n cn l nguyn nhn dn n hin tng ng x l hi nu nhit cng tc ln hn nhit nng chy ca tro. tro cng l thnhphn c hi trong nhin liu.

Cht bc k hiu l Vc, %: Cht bc ca nhin liu l cc kh nh CH4 ,cacbua hydro, COsinh ra trong qu trnh nhit phn giai on uca qu trnh chy. Cht bc ng vai tr rt quan trng, n quyt nhnhin liu c d bt chy v chy kit hay khng. Nhin liu cng nhiucht bc cng d chy v chy kit.

Nhit tr k hiu l Q, kcal/kg: Nhit tr l lng nhit sinh ra khi chyhon ton 1 kg nhin liu rn hoc lng (hoc 1m3.tc nhin liu kh).

Nhit tr ca nhin liu xc nh trong phng th nghim bng bomnhit lng kc gi l nhit tr cao lm vic ca nhin liu, khiu l Qc

lv. Khi t nhin liu trong thit b thc t nh l hi ta thuc mt nhit lng thp hn c gi l nhit tr thp lm vic, khiu l Qt

lv.Nhit tr thp lm vic Qtlv v nhit tr cao lm vic c quan h nh sau:

Qtlv = Qc

lv - 6 (9Hlv + Wp ), kcal/kg (2.2-2)Khi phn tch mu nhin liu, ngoi vic phn tch thnh phn ha hccn phi phn tch 4 c tnh cng ngh nu trn.

Ngoi 4 c tnh cng ngh trn, chng ta cng quan tm thm n 2 ctnh sau:- c tnh thnh phn cacbon qui dn:- KP = Clv + 0,375Slv. (2.2-3)- H s:

= 2,35P

lvlvlv

K

NOH 04,0126,0 + (2.2-4)

2. Tnh th tch khng kh l thuyt cn thit v sn phm khi khi tnhin liu rn hoc lng:


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Tnh lng khng kh l thuytiu kin tiu chun cn cho chy 1 kgnhin liu nhsau:

Vkko =0,0889(Clv + 0,375 Slv ) + 0,265 Hlv - 0,0333 Olv, m3.tc/kg. (2.2-5)

Tnh thtch khi kh khi t chy hon ton 1 kg nhin liu nhsau:Vkkh = VRO2 + VN2 , m

3.tc/ kg. (2.2-6)

Trong :

- VRO2 - Th tch thnh phn cc kh CO2 v SO2 trong khi c tnh:VRO2 = 1,866

100

375,0 lvlv SC + , m3.tc/kg (2.2-7)

VN2 - Thtch thnh phn kh N2 trong khi c tnh:VN2 = 0,008 N

lv

+ 0,79 . . Vkko

, m3

.tc/kg. (2.2-8)H s khng kh tha sc cp phn sau.

Tnh thtch khi m khi t chy hon ton 1 kg nhin liu nhsauT:Vk= Vkkh + VH2O , m

3.tc/kg. (2.2-9)

Trong : Th tch hi nc VH2O trong khi c tnh:

VH2O = 0,112 Hlv + 0,0124 Wlv + 1,24 gtd + 0,0161. . Vkk

o, m3.tc/kg(2.2-10)

Vi gtd - l lng hi tn du cho 1 kg nhin liu. Vi l hi t thanhoc l hi t du khng dng hi tn du cng thc (2.2-10) trthnh:

VH2O = 0,112 Hlv + 0,0124 Wlv + 0,0161. . Vkk

o, m3.tc/kg (2.2-11)

Tnh h skhng kh tha theo sliu phn tch khi:- H s khng kh tha c nh ngha l t s gia lng khng kh

thc t cp cho l v lng khng kh cn thit cho chy ht nhinliu:

= Vkktt/ Vkkot c s chy khng hon ton v mt ha hc, trong l hi thc t

bt buc phi ln hn 1. Khi 1 c thcoi l l gi.

Trong thc t th nghim l hi ngi ta xc nh h s khng kh tha bng cch phn tch cc thnh phn khi thot. Cc thnh phn l O2,RO2(bao gm CO2 + SO2), CO, NOx, SOx, ...

Ngi ta c bit ch n nng CO trong khi thot. Khi nng COtrong khi bng 0 th ch chy c coi l chy hon ton v ho hc,ngc li c coi l chy khng hon ton v mt ho hc.


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ch chy khng hon ton v ho hc, c th coi thnh phn th tchkhi kh l: RO2 + O2 + CO + N2 = 100%. V lng hm lng CO trong khic th tnh (nu khng o c) theo cng thc:

CO =65,0

1

+[ 21- RO

2- (RO

2+O

2)], % (2.2-12)

Tnh h s khng kh tha ca l theo kt qu phn tch khi nh sau: =

)5,0(21

21

2 COO (2.2-13)

O2 Nng O2 phn tch c trong khi, tnh theo % th tch.

CO Nng CO phn tch c trong khi, tnh theo % th tch.Thng thng, cc thit b phn tch khi cho ta kt qu CO theo n v

ppm, mun bin i v % th tch ta chia cho 10000.Trong trng hp t chy hon ton v ho hc CO = 0. Cng thc trn

trthnh:

=221

21

O(2.2-14)

3. c tnh nhin liu kh:3.1- Phn loi :

- Nhin liu kh gm hai loi, kh t thin nhin v kh t nhn to.Trong nhin liu kh thin nhin, thnh phn ch yu l kh mtan (CH4), mtlng nh cc kh cacbua hydro CmHn v nhng kh trkhc nh CO2, N2,H2O.i vi kh nhn to, thnh phn ch yu l CO. Thnh phn mt s loi khc trnh by theo bng sau :

Thnh phn ca cc loi kh thin nhin v nhn totrng thi kh ( % th tch)

Nhin liu CH4 CmHn CO2 H2S N2 H2 CO Qc,kJ/m3

Kh thinnhin

97,8 0,85 0,05 - 1,3 - - 36000

nt 77,8 7,1 0,2 1,0 13,5 - - 34000

7,8 1,6 72,3 - - 3 15,5 6520Kh bn cc :- Than bn- Than m 50,8 6,4 0,2 1,7 2,4 20,4 7,7 31000Kh l cc 25,3 2,6 2,8 - 8,4 54,5 5,7 17000Kh l sinh kh 0,8 - 5,9 - 3,2 53,5 36,4 10700

c tnh cc thnh phn c trong kh t


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Tn gi K hiu T khi ringkg/mm3

Nhit chyQCHkcal/mm

3

Hydro H2 0,090 2579Nit N2 1,251Oxy O2 1,428Oxit cacbon CO 1,250 3018Cacbon nic CO2 1,964Sunphit hydro H2S 1,520 5585Metan CH4 0,716 8555Etan C2H6 1,342 15226Propan C3H8 1,967 21795Butan C4H10 2,593 28338Pentan C6H12 3,218 34890Etylen C2H4 1,251 14107Pronylen C3H6 1,877 20541Bulyten C4H8 2,503 27111Benzen C6H6 3,485 33528

Nhit tr ca kh t trng thi kh c th xc nh theo cng thc sau :

Qtk= 0,01. [QCO.CO + QH2.H2 + QH2S.H2S + (QCmHn.CmHn)], kJ/m

3tc

Trong : - QCO , QH2 , ... L nhit tr chy ca cc thnh phn kh trongnhin liu , kJ/m3tc.

- CO,H2,H2S,CmHn - Thnh phn ca kh trong nhin liu, %- Th tch khng kh l thuyt cn thit cho qu trnh chy : L lng

khng kh cn thit cho qu trnh chy hon ton 1m3tc nhin liu kh, xc nhtheo cc phng trnh phn ng ho hc theo cng thc sau :

V0kk = 0,0476. [0,5CO + 0,5H2 + 2CH4 + 1,5H2S + (m + n/4)CmHn - O2 ],

m3tc/kg.- Trong thc t, gia nhin liu v khng kh khng th tip xc vi nhau

mt cch l tng nn th tch khng kh thc (Vkk) bt buc phi ln hn thtch khng kh tnh theo cng thc trn. T s gia th tch khng kh thc tvi th tch khng kh l thuyt gi l h s khng kh tha :

= Vkk/V0

kk> 1- Tnh th tch sn phm chy : trng thi l thuyt, khi chy hon ton nhin liu, th trong khi gm

c RO2, N2, H2O. thun li cho vic tnh ton, ngi ta chia thnh hai loi :

Khi kh v khi thc. Khi thc gm c khi kh v hi nc.


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Khi t nhin liu kh, th tch l thuyt ca cc sn phm chy ctnh nh sau :V0kkh = V

0RO2 + V

0N2, m

3tc/kg.V0k= V

0kkh + V

0H2O, m

3tc/kg.

V0

RO2 = 0,01 (CO2 + CO + CH4 + H2S + mCmHn), m3

tc/kgV0N2 = 0,79V0kk+ 0,01N2, m

3tc/kgV0H2O = 0,01(H2 + 2CH4 + H2S + [(n/2)CmHn]) + 0,0124dk + 0,0161V

0kk,

m3tc/kgTrong CO2,CO,CH4,H2S,CmHn,H2,N2 - T l tnh theo phn trm so

vi th tch cc kh trong nhin liu, %; dk- m ca nhin liu kh, g/m3tc.

Trong thc t v h s khng kh tha > 1 nn th tch khi thc t lnhn th tch khi l thuyt. Nhng v th tch VRO2 ch ph thuc vo hmlng cc bon v lu hunh c trong nhin liu nn th tch VRO2 khng thay

i khi thay i.VN2 = V0N2 + 0,79(-1)V

0kk

VH2O = V0

H2O + 0,0161(-1)V0kk

Th tch khi thc t l :Vkkh = V

0RO2 + VN2

Vk= Vkkh + VH2O.

- H s khng kh tha trong thc t vn hnh c xc nh trn csphntch khi. i vi nhin liu kh tnh theo cng thc :

[ ]mnHCCHHCOONN

325,05,021

794222

2

=

Lng N2 trong cng thc trn c tnh nh sau :

N2 = 100 - (RO2 + O2 + CO + H2 + CH4 + 2CnHm), %- Trong trng hp chy hon ton, cc i lng CO,H2,CH4,CnHm bngkhng.


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PHN III: CC YU TNH HNG N HIU SUT L VCC BIN PHP NNG CAO HIU SUT L HI.

C rt nhiu yu tnh hng n hiu sut l, nhng c th phn thnh 3yu t chnh: Thit b l, ch vn hnh l v cui cng l cht lng nhinliu. Trong phm vi gio trnh ny, chng ti ch cp n 2 yu t ch yu l

thit b l v ch vn hnh. Yu t nhin liu ph thuc vo khch quan, nnch c th ni rng cng dng nhin liu c c tnh gn vi c tnh nhin liuthit k cho l bao nhiu cng tt by nhiu.

1. nh hng ca thit b l ln hiu sut l v bin php khc phc:Mun l vn hnh c hiu sut cao trc ht thit b l phi m bo. Ccthit bnh hng ln nht n hiu sut l phi kn l:

- Cc b mt truyn nhit nh: cc dn ng sinh hi, dn ng qu nhit,dn ng b hm v b sy khng kh. Khi cc b mt chu nhit ny b

bm bn hoc ng cu cn s dn n h s truyn nhit km, nhit khi thot cao v tn tht nhit q2 tng cao v tt nhin hiu sut l s suygim.

Bin php khc phc l v sinh nh k cc b mt chu nhit, nh k racu cn cc ng ng chu nhit v s dng nc cp cho l t tiu chunthit k l.

- Bn th l v ui l: Khi bn th l v ui l khng kn, b hs sinh ralt gi lnh vo bung la v ui l dn n tng h s khng kh thakhi thot v dn n tng tn tht q

2theo khi thot. Ngoi ra n cn

lm qu trnh chy khng n nh c bit lu vi l c b sy khngkh thng xy ra hin tng lu ngy b sy khng kh bn mn hocmi mn dn n lt gi t b sy sang ng khi rt ln. Hin tngny khng nhng lm tng tn tht q2 m cn lm tng tiu thin choqut gi v qut khi, nu nghim trng cn dn n hin tng khngtng c cng sut l ln cng sut thit k.

Bin php khc phc l: nh k kim tra lt gi vo bung la v uil xc nh c cc im lt gi c bin php chn kn hoc nt cc

ng b sy khng kh b thng.


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- Qut gi: Khi qut gi khng nng sut (lu lng) v p lc s dnn hin tng thiu gi cp vo l. iu ny dn n hin tng chykhng hon ton v ha hc, tn tht q3, q4 tng cao, c hiu sut l vcng sut l u suy gim..

Bin php khc phc l: nh ko nng sut v p lc ca qut xem qutc nng lc hay khng. Nu khng phi tm nguyn nhn c th dorto qut, hoc do lp t khng t yu cu k thut.

- Vi t du hoc kh: i vi l hi t du hoc kh (L hi t thancng sut nh thng khng c vi t than), vi phun nh hng rt lnn qu trnh chy. Khi vi phun b mi mn, b bm bn hoc tc cc bthng dn n kh nng tn sng km hoc hn hp vi gi khng tt.iu ny s dn n gim hiu sut l.

Bin php khc phc l nh k v sinh, kim tra vi t, nu khng t yucu k thut phi thay th.

- H thng bo n: H thng bo n bao gm bn th l, ng khi,ng ng hi, nc nng, du nngnu khng t yu cu s dn ntng tn tht ra mi trng xung quanh q5. Thit bc bo n tt cngha l b mt ngoi ca n phi c nhit < 50oC.

- i vi l hi t than cng sut nh cn lu thm v ghi l (ghi cnh hoc ghi xch). Nu b mt ghi khng t yu cu k thut s dnn hin tng lt than qua ghi nhiu hoc phn phi gi khng thu.

iu ny dn n tng tn tht nhit chc q4 rt ln lm hiu sut l suygim.

Bin php khc phc l kim tra, thay th kp thi cc b mt ghi b rnghoc b hng.

2. nh hng ca ch vn hnh l ln hiu sut l:Thng thng cc l hi cng sut nhc trang b rt t cc ng ho

cc thng s vn hnh l nh: Lu lng hi sn xut, lu lng nhin liu tiuth, lu lng gi cp vo l, nng O2 trong khi thot, nhit khi thot.

Hn na cng nhn vn hnh thng ch quan tm n vn hnh an ton, tquan tm vic vn hnh sao cho kinh t nht tc l hiu sut cao nht.

V nhng l do trn, ch vn hnh l thng cht c yu cu v mtan ton, t khi t c yu cu v mt kinh t ngha l khng t c ch vn hnh ti u nht, c hiu sut cao nht.

Ch vn hnh khng ti u th hin nhng mt sau:

- L vn hnh ch thiu gi hoc tha gi - v khng c ng h theodi hay thit b kim tra. Khi vn hnh ch thiu gi, tn tht nhit

chy khng hon ton v ha hc v chc q3 v q4 s tng cao. Khi vnhnh ch tha gi s tng tn tht theo khi thi q2 v nng lng


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in tiu tn cho qut gi, qut khi. Trong c hai trng hp u lmgim hiu sut l.

- Phn phi gi khng hp l - c bit l i vi cc l hi t than.Thng cc l hi cng sut nh l cc l ghi xch, cp gi theo tng giai

on chy. Nhng do khng c ng ho tng hc gi, nn vic phnphi gi khng hp l vi tng giai on chy gy ra hin tng thiu gicc b khu vc ny nhng li tha gi cc b khu vc kia. iu ny dnn tng c tn tht nhit q2, q3, ln q4.

- Khi thay i ph ti (cng sut l) theo yu cu sn xut thng thay ich cp gi khng ph hp vi thay i lng nhin liu cp vo l.V vy, ch vn hnh c khi hp l mc ph ti ny nhng li khnghp l mc ph ti khc.

-

Cha ch n cc yu t thit bnh hng ti hiu l nh tnh trngvi t, tnh trng ghi, lt gi...Cha ch thay i ch vn hnhph hp vi s thay i cht lng nhin liu nht l than.

loi b cc yu t vn hnh nu trn nh hng xu n hiu sut l,chng ta cn th nghim, hiu chnh xc lp mt Bng ch vn hnh tiu cho l. Da vo Bng ch vn hnh ti u , ngi cng nhn s vnhnh l va m bo an ton va m bo kinh t nht, mi ph ti. Phngphp th ngim nng cao hiu sut, xc lp ch vn hnh ti u cho l sc trnh by di y.

3. Th nghim nng cao hiu sut, xc lp ch vn hnh ti u chol:

3.1.Th nghim phn phi gi ti u:i vi cc l hi t du, t kh cng sut nh, vic cp gi cho qu trnhchy rt n gin nn khng cn thit phi thc hin th nghim ny. Nhngvi l hi t than, nht l l ghi xch cn phi thc hin th nghim ny.

Trong l hi t than kiu ghi xch, gi thng c a vo l theo cp.

Gi cp I l gi t chy chnh c a vo l theo 4 hc gi di ghi cung cp cho qu trnh chy theo 4 giai on. Gi cp I thng chim trn90% tng gi vo l. Hc s 1 cp gi cho qu trnh sy. Hc s 2 cp gicho qu trnh chy cht bc v bt chy cc. Hc s 3 cp gi cho qu trnhchy cc. Hc s 4 cp gi cho qu trnh chy kit. mi hc gi c l chniu chnh ring phn phi gi cho hp l.

Gi cp II, hay cn gi l gi xit c a vo l trn ghi (phn ngngcun l). Gi cp II ch chim t 5 - 10% tng lng gi vo l t chycc sn phm chy hon nguyn.


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Th nghim phn phi gi thc cht l iu chnh v tr 4 l chn gi cp Isao cho ph hp nht vi tng giai on chy v iu chnh lng gi cp IIsao cho chy ht kh hon nguyn. Phng php tin hnh nh sau:

- Th nghim phn phi gi ti u c tin hnh cng sut l nh mcv c gin nh, h s khng kh tha c iu chnh v gimcgn thit k trong sut qu trnh th nghim.

Th nghim phn phi gi cp I ti u:+iu chnh ln lt v tr 4 l chn ti 4 hc gi cp I 4 5 v tr xung

quanh v tr thit k. Mi v tr c coi l mt ch th nghim. Trongmi ch th nghim o c v ghi cc thng s nh:

+ Phn tch cc thnh phn ca khi thot.+o lu lng gi vo tng hc gi, v tng lu lng gi vo l u

ht qut gi.

+ Ly mu than cp vo l phn tch cc thnh phn ca than.+ Ly mu x v tro bay phn tch cht chy cn li trong tro bay v x.+ Da vo kt qu th nghim, lp c tuyn: S ph thuc cc tn tht

nhit q2, q4, ph thuc vo v tr cc l chn gi cp I: (q2+ q4)= f(v tr lchn gi cp I).

+ Phn phi gi cp I c coi l ti u khi tng cc tn tht nhit q2+ q4nh nht.

Th nghim phn phi gi cp II ti u:+ Gi v tr cc l chn cp I v tr ti u xc nh c th nghim

trc.

+iu chnh ln lt v tr l chn gi cp II 4 5 v tr xung quanh vtr thit k. Mi v tr c coi l mt ch th nghim. Trong mi ch th nghim o c v ghi cc thng s nh:

+ Phn tch cc thnh phn ca khi thot.P+o lu lng gi cp II.+ Da vo kt qu th nghim, lp c tuyn: S ph thuc tn tht nhit q3

ph thuc vo v tr l chn gi cp II: q3 = f(v tr l chn gi cp II).

+ Phn phi gi cp II c coi l ti u khi tn tht nhit q3 nh nht.3.2.Th nghim h s khng kh tha ti u.Sau khi th nghim xc nh c ch phn phi gi cp I ti u, gicp II ti u cn phi th nghim xc nh h s khng kh tha ti u. y

l th nghim chnh nh hng quyt nh n hiu sut ca l. Th nghimny p dng cho c l hi t than, t du v t kh.


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H s khng kh tha c nh hng chnh n tn tht nhit ho hc, tntht nhit chc v tn tht nhit theo khi thot. Khng kh tha cn nhhng n ng x bung t v dn ng feston v b qu nhit.

- Trong th nghim ny h s khng kh tha ti u c xc nh cho 3n 4 ph ti l (cng sut nh mcc, ti thiu v hai ph ti gia).

- Ln lt iu chnh lng khng kh tha bng cch thay i tng lnggi vo l bng l chn u ht qut gi.

- mi ph ti, th nghim nn tin hnh t nht bn gi tr khng khtha: Ti a, ti thiu, v hai gi trgia.

- Trng hp l hi t than trn ghi, ghi xch, h s khng kh thathng t trong di gi tr t 1, 2 n 1, 4. Trng l hi t du, h skhng kh tha t trong di gi tr t 1, 05 n 1, 25. Mi gi tr h s

khng kh tha c coi l 1 ch th nghim.- Trong mi ch th nghim, o c, phn tch v ghi chp cc s liu

nh:

+ Phn tch cc thnh phn ca khi thot.+o lu lng gi vo tng hc gi, v tng lu lng gi vo l u

ht qut gi.

+ Ly mu than cp vo l phn tch cc thnh phn ca than.+

Ly mu x v tro bay phn tch cht chy cn li trong tro bay v x.

- Dng th quan h cc tn tht q2 = f(), q4 = f(), q3 = f()v cc tngtht nhit v (q2 + q4 + q3 ) = f().

- Da theo cc th dng c, xc nh h s khng kh tha ti u. Hs khng kh tha c coi l ti u khi cho tng cc tn tht nhit trn lnh nht: (q2 + q4 + q3 ) = f() = min.

3.3.Th nghim cn bng nhit, xc lp bng ch vn hnh ti u.- Mc ch cc th nghim ny l xc nh cc tn tht nhit trong nhngiu kin vn hnh ti u cc ph ti khc nhau. T xc nh cph ti kinh t nht (c tuyn kinh t - k thut) ca l v lp Bng ch vn hnh ti u cho l.

- Th nghim c tin hnh da trn cc ch chy ti u tm ratrong cc th nghim trc nhT: phn phi gi cp I, cp II ti u, h skhng kh tha ti u.

- Cc mc ph ti nhit cn th nghim l: Cng sut l = 70% cng sutnh mc; Cng sut l = 80% cng sut nh mc; Cng sut l = 90%

cng sut nh mc v Cng sut l = 100% cng sut nh mc. Thi


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gian th nghim cho mt ph ti nhit t 3 n 4 gi. Mi mc ph tithng lm 4 5 ch th nghim.

- Ghi chp s liu, mi ch 30 pht mt ln.-

Trong cc th nghim ny phi o c v ghi chp tt c cc thng s sau:1. Nhin liu:- Ly mu nhin liu trong sut 1 ch th nghim, xc nh cc

c tnh trung bnh ca nhin liu.2. Ph ti nhit, Lu lng v cc thng s hi:- Lu lng hi v nc cp c xc nh theo cc ng ho lu

lng hi v nc cp. Cc ng ho lu lng phi c kim tra,hiu chnh chnh xc trc khi th nghim.

- Lu lng hi t dng v lu lng nc x ly theo ng h vnhnh (nu c) c kim nh trc khi th nghim, hoc lp tmi.

- p lc, nhit hi qu nhit, nhit nc cp, nhit nc phungim n, lu lng nc gim n o theo ng h vn hnh ckim tra trc khi th nghim.

- i vi l t du o lu lng hi sy du, hi sy gi, hi ho mdu theo ng h ti ch kim tra trc khi th nghim. o nhit hi u vo - u ra cc b sy du, b sy khng kh bng hi,nhit hi ho m trc cc vi t bng cc ng h ti ch

kim tra.3. Nhit v thnh phn khi:

- Nhit bung la o bng cc loi ho quang k xch tay.- Nhit tuyn ng khi o bng ng h vn hnh c

kim tra trc khi th nghim, c tho kim tra bng nhit kthu ngn hoc nhit kin tr.

- Phn tch thnh phn khi cc thit din: Ra khi bung la, saub sy khng kh cp I, sau b kh bi.

- mu ht qut khi, sc ht bung la.4. Lu lng v nhit gi nng lnh:

- o lu lng gi cc im: u ht qut gi, cc ng gi nngsau b sy, ng gi vo vi phun cc cp: I, II. ng thi ghi mtt c cc l chn trn cc ng ng k trn.

- o nhit gi lnh u ht qut gi, trc v sau b sy khngkh.

5. Ly mu tro, x ti cc im ly mu phn tch cht chy cn litrong tro, x. T l tro bay / tro trong x ly theo s liu thit k.


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6. Tnh ton cc tn tht nhit, hiu sut l theo cc mc ph ti thnghim. Lp c tuyn = f(D), v xc nh ph ti kinh t nht cal. Lp Bng ch vn hnh ti u cho l hi.

PHN IV: CC I LNG CHNH CN O LNG TRONG THNGHIM HIU CHNH L HI V MT S THIT BO LNG

PHC V CHO CNG TC TH NGHIM HIU CHNH.4.1- Cc i lng chnh cn phi o lng trong th nghim hiu chnh :4.1.1. Nhin liu :a, Lng tiu hao nhin liu :- i vi l hi t du hoc kh t phi o lu lng du hoc kh t. Vi lhi t than th lng than a vo l xc nh bng cch cn trc tip i vil hi nh hn 50T/h. Vi loi l t than ln hn th lng tiu hao than xcnh theo cn bng nhit ngc.b, Thnh phn cbn ca nhin liu v nhit tnh ca tro, xc xc nh theo

mt mu trung bnh trong khong thi gian lm th nghim.4.1.2. Lu lng v cc thng s hi :- Lu lng hi v nc cp c xc nh bng cc ng h lu lng vnhnh kim tra. Nhit hi, p lc hi, nhit nc cp cn c o bngcc ng h c kim tra, hiu chnh.4.1.3. Nhit v thnh phn khi :- Nhit bung la o bng cc ho quang k qua cc ca xem la. Nhit khi trn ng khi o bng nhit k thu ngn v cc loi nhit k khc.- Phn tch khi bng cc my phn tch khi xc nh h s khng kh tha

v cc kh thnh phn (RO2, O2, CO, H2, CH4, CnHm).4.1.4. Lu lng v nhit gi :- Lu lng gi : o bng cc thit bo p lc hoc vn tc. Lu lng gic o ti u ht qut gi, trc cc vi phun cc cp, cc ng gi nng sauthit b sy khng kh.- Nhit gi : Nhit gi o trc v sau qut gi, sau b sy khng kh,trc vi phun gi cp 1.4.1.5. in t dng :- Lng in t dng o bng cc cng tin vn hnh kim tra.

4.1.6. Mu tro, x


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25/25

Annual steam production == steam production rate x annual operation hours= 10,000 kg/hr x 7,200 hr/yr = 72,000,000 kg/yrEnergy (Q) required for 72,000,000 kg steam == mass x (hg hf) boiler efficiency

= 72,000,000 kg steam/yr x (660 60) kCal/kg steam 0.72= 60,000,000,000 kCal/yrMass of coal (amount of coal required for annual steam production)= Qrequired GCVcoal=60,000,000,000 kCal/yr 4,200 kCal/kg coal= 14,285,714 kg coal = = 14,285 tons coal per year3. Calculate the annual fuel cost savings in million US$Cost of fuel oil= Mass of oil x Cost of oil= 5,268 ton oil/yr x US$ 300/ton= US$ 1,580,400 per year

Cost of coal= Mass of coal x Cost of coal= 14,285 ton oil/yr x US$ 45/ton= US$ 642,825 per yearFuel saving for coal boiler= Fuel cost oil boiler Fuel cost coal boiler= US$ 1,580,400 US$ 642,825= US$ 937,575 per year

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