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final exam 2007 solutions

# final exam 2007 solutions - Chemical Engineering 140 Final...

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Unformatted text preview: Chemical Engineering 140 December 14, 2007 Final Examination Solutions (100) 1. A Steam Heated CSTR (20) a. Steady mass balance on species A for CSTR is 0 =CSSSQ—CSQ—kSCSV So CA/CASS =1/{l+knr) where er/Q Finally, conversion is XSHS) =kSr/(l+kSr) (3 O) b. Steady energy (enthalpy) balance on CSTR 0 = Q pSIJ'SS — Q pSﬁSm + Q where Q = QAH; —T) is the heat ﬂow into the reactor Likewise HSSS — HSS = (7S. (1" * TS ) Solving for T gives Clearly, heat transfer characteristics of the steam condenser LIA along with the thermal mass of the inlet stream Qggém weight the inlet and steam temperatures to set the reactor temperature. (30) c. Conversion at Thy insPection is XA(T)=kr/(l+kr) where k=kS(T/?:S) Hence we can solve for MA /XS (3;) as AX _ k; _ gar/To) _ {Caz-(T/SQ—l) A 1+knr I+kor(T/Y;) [1+kar][1+knr(T/I;)] Therefore, AXA _ (Tm—1) Xian) ‘ [1 mar/m (10) d. An unsteady mass balance on Species A over the reactor gives ac}; a: V = CAmQ _ CAQ __. kCAV Rearrangement gives V ) dCA C CAinQ ( ‘—'+ A“ . Q+kV d: Q+kV InSpection gives the characteristic time as 1' 21+kr (10) e As long as the exiting condensate contains some amount of vapor so that TS remains ﬁxed the steam mass ﬂow rate plays no role. Wmﬁ wm& Ctr—"Mal 75H Eul‘bmd “R j Um: 10 EM“ H" °R a m Wagon 0% ’11 aha am 3'5] msvohm 60Z muelr be, 4% Imam rm‘l'ad. 1 TILED!“ 3 5615 me] mw.OMm®-%6 = 55m‘ d3 '— H w mm Low (molar 15 ! Cﬂolaﬂ‘l’. J M 3W 81/ i : a) N"; EDI-l: ”45%;,“ bij/jmol- I ’3ch (4;.qu 2' "L‘Hbsal Li‘s/51:19] ARM“ -‘-l?5|b.5|l K51»! 5" CON/41+ has [I] KS/ﬁm‘ M40 KSlmL. E r :9 AHcﬁgHm =' 5+” ELmolag‘ !—\EDQD(€ K3 \ mo {3.3 : K3 5 I -54] g; I I ml [0.73 .m K5 J}AHC’IOL+ : (jhwl ”42-3 ”IL _ 5551-1 “1'.— ' MC, 3le “,1: 042(2572) + 0.250355% = 391.5% ‘ij, ,5 a assume [L 03} 001mm: MM = ”325.6% x4000 =— 535%; 143. WM“ 41> 36? 60M A” w‘ ﬂqsoLwl- How Web 1.5 W7 33610 = ’51.5%\/ .—_> \/= 1062 mL, : f 7— so 50 W "B12530 ~:. LEM/“L: ﬂy Q mm, M +13 gd- 44% 3am. amoorf 0{ M61" ‘E’om 3450M" d5 vFro-m burn‘vi IL OOHML. How WIULh od'qnmis 'm +MT gawkot . M WK 61: we, £00m W mm, mm ’[OQZWL . 6% BQSOL‘Ol +0 (30" “My Same, MUM Vol/«IQ, as IOOO “L! 0% odnm. ' LOU. mL x 0-23 h“ll— 0(7qu 7:. Qﬁﬁb H1L- {Dd—QM. WL aasdm H 1000—- %qu.(p __ __ o . [ % ————————————-IOOO .. ,Lso ->'l57 M Stu/m6.) i I 50/ L03”) 2070 EA’OH, Wt NH SGML \5'70 edema, 1 :0) Th. \$553; gvm‘ﬂ 0+ HOP) 15 lay ”Hm/L W 65‘ n—ocbm baa-use, (air ‘gvorahlax 'Inermoteiwb/ Ir/I‘I'Q/GOQOIIS (Ml, Hwﬂff 6n Jamil) ‘Hd' OCCUK WFH‘) EH)” 301' “0+ in mmmrbon. idqp‘ Ewﬁ’d ’15 (Mi Sold, [@1ch Of (305 R91; ‘Hmﬂ' ‘Is oﬁmvai “Rom biomass. Soda as Weed, 00an or oH-w PW‘Jﬂv- Q) Emmgs. muer bm mnwhéqub 1% MM, use. "We «quires Wni my usmﬁ sheen . E“ramﬁb WM [3L . mum (mi. kawdeciu .1} urn/5+ be, fl'farsPorf'QJk “lb (L Edit)“ 4'0 be, 1590615366” 1+ VIM/5+ “PM he, twig!” wwﬁei 41> RM, (M W ”MHjPofM ‘For CQASITJbaLon i Emma mam-L Lin {Moémhar’n ‘1‘1: Pmr‘mulh (HP, ["irrx—Ewb. ...
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