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L4slides - Ex Multieffect Evaporator Seawater which...

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Unformatted text preview: Ex. Multieffect Evaporator Seawater which contains 3.5 wt% salt (assume all NaCl) is Fed to triple effiect evaporator at 30,000 lbmfh. The mole fracticm NaCl in outlet from last stage is 0.01593. Rppvaximately same quahtity of water is boiled off in each atage. Fihd the evaporatioh rate in each stage and wt% NaCl between End &'3Pd Stages. // “wwmmm 4K' \ ‘\a¢L_m__WW“wflmemwiflm . 1 - . ' .. . ......,v , 'Izlg ' 2 13:." ' 1"3‘ . ' '.ll. -- .1: - .L‘ . .1'. . :1’:'-:--.:; I ,l l' :‘I' ’ I l. , ‘ l‘ 'l Lecllal'e#45altEx.ub Inmm m: {(1, 1, 1, o, o, 0}, (1, o, o, o, o, 0}, {"1" "1r 1: 1-: 1r 0}! {'11 or or 3-: Gr 0}: {0, U, 1, ml, -1: 1}: {0, o, o, —1, 0, 0.04981} 0mm: (('1,1,1,0, 0, 03, {1, o, o, o, o, 0), {-1,-—1,1,1,1,0}, {—1,o,o,1,o,o), {0,0,1,w1,~1,1),{0,0,0,~1,0,0.0498}) Ian}:= m.{nsl, nwl, w, 1192, an, Qp} == {30000, 1050, 0, 0, 0, 0} Outf2}= {nsl +nw1+w, nsl, —nsl+ n52 unwl +nw2 +w, —nsl +1132, ——n52 ~nw2 +Qp+w, «n52 + 0.0498 Qp}l== {30000, 1050, 0, 0, 0, 0} 113(3):: Solve[%, {nsl, nwl, w, 1152, nw2, Qp}] Out[3]= {{nsla 1050., 3:1le 25978.1, w—) 2971.89, 1132—) 1050., nw2 —:-23006.2, Qp-e 21084.3}} InI4J:m 3.050. / (1950. +23806.2) Outf41= 0. 0436478 recycle, without to refer naterial ,l enters system overall des the reasons : of the include 5, them. :arately :15 in a 0 high, v The following example illustrates a material balance calculation for a nonreactive process that includes recycle. EXAMPLE 4.5-1 An Evaporative Crystallization Process The flowchart of a steady-state process to recover crystalline potassium chromate (K2004) from an aqueous solution of this salt is shown below. Fitter cake K20r04 (solid crystals} 49.4% rtztnro4 Crystallizer and fitter 4500 kg/h 33.3% K2004 Evaporator 36.36% K; Cr04 solution {the crystals constitute 95% by mass of the fitter cake) Fittrate 35.36% KZCrO4 solution Forty—five hundred kilograms per hour of a solution that is ~§~K2Cr04 by mass is joined by a recycle stream containing 36.36% KzCrO4, and the combined stream is fed into an evaporator. The concentrated stream that leaves the evaporator contains 49.4% K2Cr04; this stream is fed into a crystallizer in which it is cooled (causing crystals of KzCrO4 to come out of solution) and then filtered. The filter cake consists of KZCrO4 crystals and a solution that contains 36.36% KZCrO4 by mass; the crystals account for 95% of the total mass of the filter cake. The solution that passes through the filter, also 36.36% K2004, is the recycle stream. Calculate the weight of water removed in the evaporator, the rate of production of crystalline K2CrO4, the ratio (kg recycle)/(kg fresh feed), and the feed rates that the evaporator and crystallizer must be designed to handle. LectuI'chRecycleEthb 111(5)::- m=[{-1, 1, 1, o, o, o, 0}, {-0.3636, 1, O, 0, 0, 0, U}, {0, r1, -1' 3., 1r 0, O], {0, —1, O, 0, 0.494, G, 0}, (1! 0: or or “'71! 1: 1}: {0.3636, 0-, G, 0, -D.494, 1, 0.3636}, [0, o, 0, 0, 0, «0.05263, 1}} Out[5}= {{-1,1,1,0,o, 0,0}, {—0.3636, 1, 0, o, 0, U, 0), (or “'11 “1: 11 1r Or 0}: {or "1: or 0: 0-494r 0: O}! {1: ol Or 0! "‘11 1: 1}: {0.3636, 0, O, 0, —0.494, 1, 0.3635}, {0, 0, 0, O, 0, "0.05263, 1}} I:1[6}:= m. {3, mek, mew, Qw, Fe, PC, PS] (4500., 4500. /3, o, o, o, o, 0} Outf61= {mek+mew—R, mek~0.3636R, Fcumek—mew+Qw, 0.494FC—mek, ~FC+PC+PS+R, ~0.494FC+PC+U.3636 Ps+0.3636R, —O.05263PC+PS]=={4500.,1500., 0, 0, 0, 0, 0} In1'7]:= Solve[%, (R, mek, mew, Qw, Fc, Pa, 135)} Outr7l== {UK—25633.8, meek-e 3548.45, mew-a 5585.35, Qw—a2950.7, 1313-9718109, Fez-41471.83, PS ->’7'7.4627}] I:1[8}:== 5633.8 [4500 OutI8J= 1.25196 Inf9}:= 4500 +5633.8 Out[9]= 10133 . 8 Humidily H20 Urine Woler Reciomolion Reclamation lOO % 300 % Wash Woler ReclamatiOn lOO °/o / Metabolic H20 2 H20 in Food 0.66 ab 02 for Leak 0.15 lb Moke up 0.23m Figure 2.17 Water and oxygen recycle in a space vehicle. In addition, balances can be made about combinations of subsystems, such as the process plus the separator (3 + 4). Only three of the four balances (a «~(d) are ;nr1ahnnr10nf Fnr nnP. cnmnnnenL However. balance 1 will not include the recycle ...
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L4slides - Ex Multieffect Evaporator Seawater which...

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