Optimization Analysis of Multiple Steam Turbines and Condensers in Paper Mill Power Plant

Transcription

1 Europea Aocato for the Developet of Reeable Eerge, Evroet ad Poer Qualty (EA4EPQ) Iteratoal Coferece o Reeable Eerge ad Poer Qualty (ICREPQ 0) Graada (Spa), 3th to 5th March, 00 Optzato Aaly of Multple Stea Turbe ad Codeer Paper Mll Poer Plat Jog Tao, Huab Lu, Jgeg L, Yogju Y, Yag Zhou ad Jgja Ja State Key Laboratory of Pulp ad Paper Egeerg South Cha Uverty of Techology Tahe, Guagzhou, Guagdog, 50640(Cha) Phoe/Fax uber: , e-al: jtao@cut.edu.c Gold Eat Paper (Jagu)Co.,Ltd. No.8, Xg Gag Dog RD., Dagag, ZheJag, JagSu, 3 (Cha) Eal: j.j.ja@goldeatpaper.co.c Abtract. The coolg toer ater fluece o turbe ad codeer theral effcecy ere reearched th paper ad the codeer orkg codto pact to turbe theral effcecy a alo dcued. Baed o the bac odel of turbe, codeer ad coolg ater, the optzato odel for the yte of turbe, codeer, coolg ater ad coolg ater toer fa a propoed. Oe paper ll poer plat hch ha ultple turbe, codeer ad coolg ater toer a take a a cae to verfy the optzato odel, the reult hoed that the optzato odel a practcal ad ueful for paper ll poer plat; t ca prove poer plat effcecy ad brg good ecoocal perforace for paper ll. Key ord : ultple turbe ad codeer; coolg ater; load dtrbuto optzato; paper ll. Itroducto Paper ll, a kd of factory hch produce varou grade of paper, oaday are gettg ore ad ore heaver eergy cot preure Cha becaue of the rg prce of ra eergy ateral a ell a the fluece of Chee goveret eergy avg ad draage reduce polce []. Poer plat, the hgh level eergycoupto ecto paper ll, play a portat role o the ll de eergy effcecy. At preet, ay taff paper ll poer plat pay ore atteto o tea turbe, boler ad gore the codeer fluece. Actually, the codeer ork codto have a portat pact o tea turbe effcecy[]. Codeer, a kd of heat trafer hch ued to codee vapour to lqud, a dely ued the coalfred poer plat paper ll. Becaue the a purpoe tea poer plat paper ll to geerate axu electrcty at hgh effcecy, ad the ot effectve ay for reachg th a to ue codeer. Codeer creae the ethalpy drop ad turbe ork by loerg the turbe outlet preure. The loer the preure, the hgher the effcecy ad poer are. Codeer ca be clafed to group: urface ad drect cotact. At preet, the frt type otly ued paper ll poer plat[3]. Ad oe paper ll poer plat taff lke to cloe the fa of coolg toer to ave electrcal poer; actually, t ot a good ay for turbe effcecy. Th paper ll aalyze the codeer ad turbe charactertc ad focu o the reearch of the relato betee the tea turbe effcecy th the codeer orkg codto a ell a the coolg ater toer let ad outlet ater teperature ad flo rate ad get the ecoocal operato et for poer plat.. Model Extrapolato The prcpal cycle of the tea ege Rake Cycle. A cheatc of a ple tea poer plat th codeer ad t h- dagra are ho Fg.Rake h Fg. The cheatc of a ple tea poer plat ad t h- dagra 4 RE&PQJ, Vol., No.8, Aprl 00

2 Cycle a deal cycle here all the proce take place a reverble. Actual cycle dffer fro deal cycle becaue of oe rreverblte. Theral effcecy of the actual cycle accordg to Fgure : η th = [( h h ) ( h h )]/( h h ) () Ad the turbe poer a () P = ( h h ) η () e here h the ethalpy (kj/kg), the tea a flo rate (kg/) ad η the echacal effcecy of the turbe. A ee () ad (), to axze the theral effcecy ad poer, the ethalpy drop the turbe ut be creaed. There are aly to ay to reach th a. Frt oe to creae the turbe let teperature ad preure, the other oe loerg the turbe ext preure, other ord to ue a codeer a Fgure. Fro Fgure ad Fgure, the heat fro the ext tea a (3) Q = ( h h ) (3) 3 3 Ad the heat that coolg ater get: Q = c ( T T ) (4) p o Fro the equalzato of Q 3 ad Q e get (5) = [ ( h h )]/[ c ( T T )] (5) 3 p o Where deote the coolg ater flo rate (kg/), c p the pecfc heat of the ater (kj/kgk) ad ( T T ) o the teperature dfferece of the coolg ater. Q = A k T (6) here k the heat trafer coeffcet (W/ K), A the heat trafer area of the codeer ( ) ad ea teperature dfferece, a (7) T the log T = [( T T )]/[l( T / T )] (7) e e T dfferece betee aturato tea teperature ad coolg ater let teperature ( T T T T = ), e dfferece betee aturato tea teperature ad coolg ater ext teperature Te = ( T To ). If e take the legth of the coolg ater tube a L, er daeter of the tube a d, outer daeter a d a ad tube uber a, A ca be rtte a (8) A π d L Coolg ater velocty the tube: = (8) a v = /[( ρd )( π / 4)] (9) here ρ the dety of ater. Coolg ater heat trafer coeffcet a (0) α = ( av / d )( + b T ) (0) v here T the ea teperature of the coolg ater ad a, b,, are the cotat factor. If e deote the drte factor a ϕ the α ' = ϕ α () ϕ value ca be take betee 0.65 ad 0.75[4]. The overall heat trafer coeffcet k ca be dra fro () = + + () ' / k (/ α) ( δ / λ) (/ β ) here δ the tube thcke, λ the theral coductvty of the tube ateral ad β the heat trafer coeffcet of the tea β value take betee 000~ 6000 (W/ K). Fg. The cheatc of a urface type codeer The heat traferrg codeer a (6) The poer of the coolg toer fa P = P η (3) f r f 43 RE&PQJ, Vol., No.8, Aprl 00

3 here effcecy. P the rated poer of the fa, r η f the fa Whe e decreae T through opeg the coolg fa, the coolg ater ll decreae T hch ll fluece h ad T ca be calculated th the theral balace th the help of (6), (8) ad (). Ad the fal electrcal eergy geerato optzato odel a (4) (4) E = [ '( h h ) η ( h h ') η ] ( P η ) r f 3. Reult ad Dcuo There are four boler ad four turbe. Turbe #,,3 ad boler #,, 3 ere bult frtly ad hare a a tea ppe. Turbe #4 ad boler #4 ere bult after everal year.turbe a paraeter are a Table I. Table I.-Ma capacty parater of tube Ite Ut Deg capacty paraeter # #,3,4 Rate poer k Stea preure Mpa.3.3 Medu preure extractg tea preure Medu extractg tea aout lo preure extractg tea preure lo preure extractg tea aout Mpa.6.6 t/h 30 50/50/90 Mpa t/h 45 95/95 /300 Exhaut preure Mpa A. Turbe Effcecy Effcecy 85.00% 80.00% 75.00% 70.00% 65.00% 60.00% 55.00% # # #3 #4 Turbe Exergy Effcecy Theral Effcecy Fg.3 Exergy ad Theral effcecy of the turbe 3 The turbe exergy ad theral effcecy ca be got a Fgure 3. For Table I, e ca fd turbe #, 3, ad 4 are the ae rated poer turbe, but fro Fgure 3, ther theal effcecy are dffret ad turbe #4 ha the hghet effcecy ad turbe #,,3 theral effcecy are lo. B. Codeer Operato Paraeter The codeer operato paraeter are a Table II. Table II.-Codeer operato paraeter Ite Codeer Teperature, Teperature outlet coolg ater, To, Teperature let coolg ater, T, Turbe codeer T o -T, Fro Table II, e ca fd the teperature dfferece of #,, 3 betee outlet coolg ater ad let coolg ater are too bg hch exceed the oral rag, th a portat caue lead to a lo turbe effcecy for trube #,, 3. C. Coolg Water Toer Boler #,, 3 ad turbe #,, 3 hare oe group coolg toer hch e aed coolg toer group #, after exteo project of the paper ll, boler #4, ad turbe #4 ue oe e group coolg toer hch e ae group #. Fro the data provded by the paper ll poer plat taff, the coolg capacty of group # lack of the dead of turbe #,, 3 codeer; th aother caue to lead to turbe #,, 3 lo theral effcecy. But coolg toer group # coolg capacty f exce for turbe #4, ad the taff cloe group # oe fa to ave eergy. D. Optzato Strategy Fro Equato (4), e ca adjut the codeer let tea ad coolg ater teperature to optze the total yte theral effcecy. For turbe #4 ad coolg ater toer group #, e fd turbe #4 ha hgh theral effcecy, ad the atched coolg ater toer capacty exce, o e ca ru ore coolg fa to deceae the coolg ater teperature to prove the tea aout cooled by coolg ater, ad reduce turbe #4 extractg tea aout to let t produce ore electrcty ad produce le extractg tea. For turbe #, ad 3, e ca deceae the aout hch flo to the codeer ad prove extractg 44 RE&PQJ, Vol., No.8, Aprl 00

4 tea aout, deceae the codeer teperature, to let turbe #, ad 3 produce ore extractg tea ad le electrcty. E. Optzato Reult To get the good ecoocal perforace, the optzato tep ere carred out a the follog: Frt, the ele three coolg toer fa group # coolg toer ere opeed to cool the ater fro 3 to 4.5 for turbe #4, ad keep the ater flo rate a a cotat. Secod, creae tea let aout for turbe #4 ad deceae t extractg tea aout; eahle, decreae tea let aout for turbe #,, ad 3 ad creae ther extractg tea aout, through turbe #4 ad turbe #,, 3 adjutet to keep the total extractg tea aout a a cotat value to eet the producto requreet. Fally, the tea let flo rate for turbe #4 ll creae hch ll reult geeratg ore electrcty, but the heat ll be carred aay by the cooler ater through opeg three ele coolg ater fa ad the codeer teperature ll keep a cotat value. Turbe #, ad 3 codeer teperature ll deceae th the deceae of tea let hch ll lead to geeratg le electrcty. The codeer operato paraeter optzato reult ere a Table III. Table III.- Codeer operato paraeter before ad after optzato Ite # # # 3 # 4 Before After Before After Before After Before After Heat trafer area, Coolg ater let teperature, Coolg ater outlet teperature, Stea codeg teperature, Coolg ater teperature dfferece, Heat trafer teperature dfferece, Log ea teperature dfferece, t K value Stea let flo rate, t/h Stea flo rate dfferece, t/h Fro Table III, the ecoocal perforace a lt Table IV, ad t ca be foud there 660 Kh/h electrcty ll be produced after optzato. Table IV.- the optzato reult for geeratg ore electrcty Ite Turbe # Turbe # Turbe #3 Turbe #4 Coolg toer Total RE&PQJ, Vol., No.8, Aprl 00

5 Before After Before After Before After Before After Before After Stea let flo rate, t/h Geerated electrcty, Kh/h Electrcty dfferece, Kh/h fa 4. Cocluo The optzato for turbe, codeer ad coolg ater toer ca creae the paper ll poer plat electrcty geerato, ad obta good ecoocal reult through adjutg oe operato paraeter thout captal vetet. Th kd of optzato trategy ca be appled to the ultple coolg toer, codeer ad turbe paper ll poer plat. Ackoledgeet The author ould lke to ackoledge the facal upport of Guagdog-KogHog Key Feld Reearchg Foudato ( Grat No ), Guagdog Provce Scece ad Techology Project Foudato (Grat No. 007B ), Natural Scece Foudato of Cha (Grat No ) ad State Key Laboratory of Pulp ad Paper Egeerg Youth Iovato Progra Foudato,South Cha Uverty of Techology. Referece [] B.Agele, C. Negro, C. Mote. ad E. Fuete. The Challege of utaable paperakg, Evroetal Scece &Techology, (004), pp [] Y.J.Y, J.S. Tao, J.G. L ad H.B.Lu. Exergy aaly of Co-upply of Heat ad Poer yte the pulp ad paper ll. Proceedg of Iteratoal Coferece o Pulpg ad Paperakg ad Botechology Najg, pp [3] H. Taguch, T. Nakahara ad N. Ara, Exergy aaly o cobuto ad eergy covero procee. Eergy, (005). 30: pp. -7. [4] G. YAN ad J. ZHOU, The deg ad applcato of evaporato codeer. Refrgerato ad Ar Codtog (003). 3( (3) ): Pp RE&PQJ, Vol., No.8, Aprl 00