?D2r2t1?t2??W2??2??（Fc?Wc）p01pw?r???r2?2??W1r2t1?t2????2??（Fc?Wc）p01pw?r? r???? ②
22?1???2177.3?2230.2W?4.183W132.86?112.93?1?(10347.22?3.51)2230.2???0.9404W1?307.29 对于第Ⅲ效，同理可得
W??D3r3t2?t3?3??3??r?（Fc?Wc?Wc?3?p01pw2pw）r3??????W2r3t2?t3?3????r?（Fcp0?W1cpw?W2cpw）3?r3??? ?1???2230.2?2354.9w.183W112.93?63.76?2?(10347.22?3.5?41?4.183W2)2354.9????0.0873W1?0.8599W2?756.17 又因为W1?W2?W3?6898.15kg/h ④ 联解上面①②③④式，可得
W1?2092.78kg/h
W2?2275.34kg/hW
3?2530.03kg/hD1?3008.94kg/h4.5蒸发器传热面积的估算
SQii?KΔt iiQ1?D1r1?3008.94?2138.5?103/3600?1.7874?106W
?t1?T1?t1?143.4?132.86?10.54℃
SQ11.7874?1061?Kt??84.79m2
1?12000?10.54Q2?W1r1??2092.78?2177.3?103/3600?1.2657?106W
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③
?t2?T2?t2?T1??t2?130.5?112.93?18.12℃
Q21.2657?106S2???69.85m2
K2?t21000?18.12Q3?W2r2??2275.34?2231.0?103/3600?1.4105?106W
?t3?T3?t3?T2??t3?110.47?63.76?46.71℃
Q31.4105?106S3???60.39m2
K3?t3500?46.71误差为1?SMIN60.39?1??0.29?0.05，误差较大，应调整各效的有效温度差，重复SMAX84.79上述计算过程，使三个蒸发器的传热面积尽量相等。
4.6有效温度的再分配
S?S1?t1?S2?t2?S3?t384.79?10.54?69.85?18.12?60.39?46.71??66.08m2
10.54?18.12?46.71??t重新分配有效温度差，可得
S184.79?t1??10.54?13.52℃ S66.08S69.85?t?2?2?t2??18.12?19.15℃
S66.08S360.39?t???t??46.71?42.69℃ 33S66.08???t14.7重复上述计算步骤 4.7.1计算各效料液
由所求得的各效蒸发量，可求各效料液的浓度，即
x1?Fx010347.22?0.15??0.188 F?W110347.22?2092.78Fx010347.22?0.15??0.260
F?W1?W210347.22?2092.78?2275.34x2? x3?0.4 5
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4.7.2计算各效料液的温度
因末效完成液浓度和二次蒸气压力均不变，各种温度差损失可视为恒定，故末效溶液的温度仍为63.76℃,
即
t3?63.76℃
则第Ⅲ效加热蒸汽的温度（也即第Ⅱ效料液二次蒸气温度)为
??63.76?42.69?106.45℃T3?T2??t3??t3
??2246在此温度下汽化潜热r2.66kJ/kg 用公式 ???f??a 再次对料液温度进行估算
0.0162?(106.45?273)2??2?f??a?(102.3?100)?2.39℃
2246.66 不计液柱静压力及流动阻力而引起的温度差损失，故第Ⅱ效料液的温度为
.45?2.39?108.84℃ 2?106 t2?T2???? 同理
T1??t2???t2?108.84?19.15?132.08℃
在此温度下汽化潜热：
.65kJ/kg r1??21710.01162?(132.08?273)2??f??a??1??101.5?100??1.84℃2171.65
??132.08?1.84?133.92℃t1?T1???1
由于不考虑液柱静压和流动阻力对沸点的影响，且溶液温差损失变化不大，故有效总温差不变,即
12
??t?13.52?19.15?42.69?75.36℃
温度差重新分配后各效温度情况列于下表：
表4-2 三效蒸发器各效的温度
效次 加热蒸汽温度，?C
有效温度差,?C 料液温度，?C
Ⅰ T1=143.4
Ⅱ T'1=132
Ⅲ T'2=106.
??13.52?t1t=133.9 ?t11?9.3??19.15?t2t2=108.
??42.69?t3t3=63.76
4.7.3各效的热量衡算
效次 Ⅰ Ⅱ Ⅲ Ti?，?C
ri?,?C
132.08 2171.65
106.45 2246.6
60.1 2354.9
第Ⅰ效
?D1r1t0?t1??W1??1??Fcp0?r??r1??1?.580?133.92??2138?1??D1?10347.22?3.5?? ①
.652171.65??2171?0.9847D1?899.19 第Ⅱ效
?D2r2t1?t2???W2??2??（Fcp0?W1cpw）r2???r2???W1r2t1?t2????2??（Fc?Wc）p01pw?r??r2??2?.65133.92?108.89??2171?1??W1?(10347.22?3.5?4.183W1)?.662246.66?2246??0.8200W1?403.47
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②
第Ⅲ效
?D3r3t2?t3???W3??3??（Fcp0?W1cpw?W2cpw）r3???r3???W2r3t2?t3????3??（Fc?Wc?Wc）p01pw2pw?r?r3???3?.66108.89?63.76??2246?1??w2?(10347.22?3.5?4.183W1?4.183W2)?.92354.9?2354???0.0802W1?0.8739W2?694.04 又因为
③
W1?W2?W3?6898.15kg/h ④
联解上面①②③④式得
W1?2060.70kg/hW2?2299.31kg/hW3?2538.14kg/hD1?3005.88kg/h 与第一次计算结果比较，其相对误差为
1?1?1?2060.70?0.01422090.352299.31?0.0001
2299.382538.14?0.01182508.42计算相对误差均在0.05以下，故各效蒸发量的计算结果合理。其各效溶液无明显变化，不需要重新计算。
4.7.4 蒸发器传热面积的计算
Si?Qi KiΔtiQ1?D1r1?3005.88?2138.5?103/3600?1.7856?106W
??13.52℃ ?t1
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