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(已知:25℃水的饱和蒸汽压为3.1684kPa;40℃水的饱和蒸汽压为7.3766 kPa 、汽化潜热为2401.1kJ/kg)
9. 在常压干燥器内干燥某湿物料,将500kg/h湿物料从最初含水量20%降至2%(均为湿基)。t0?20℃,H0?0.01kg/kg(绝干气)的空气经预热器升温至100℃后进入干燥器,废气温度为60℃,忽略热损失。试计算:
(1)完成上述干燥任务所需的湿空气量; (2)空气经预热器获得的热量。
参考答案
一、判断题
1. A 2. B 3. A 4. B 5. B 6. B 7. B 8. B 9. A 10. A 11. B 12. A 13. B 14. A 15. B
二、单选题
1. D 2. D 3. B 4. A 5. C 6. A 7. A 8. B 9. A 10. C 11. D 12. C 13. B 14. D 15. B 16. B 17. C 18. A 19. C 20. B 21. D 22. D 23. C 24. C
三、多选题
1. ABD 2. ABC 3. ABC 4. BC 5. AC 6. AD 7. ADE 8. BC 9. BD 10. BCD 11. ABC 12. BCD 13. BD 14. AC 15. ABC
四、计算题
1. 解:(1)y2?y1(1??)?0.02?(1?0.92)?0.0016
y1?y2y1?y20.02?0.0016?L?????1.220 ??Gx?xym?x0.021.3?0.0003??min1e212∴
L?L??1.6?61.?220???1.GG??min1.952
根据全塔物料衡算,得:
x1?x2?G10.0003?2?y1?y?2???0.0?L1.9520.?6?001 0.00943?3(2)?y1?y1?mx1?0.02?1.3?0.00943?7.75?10
?y2?y2?mx2?0.0016?1.3?0.0003?1.21?10?3
?y1??y2(7.75?1.21)?10?3?ym???3.52?10?3
ln??y1?y2?ln?7.751.21?(3)NOG?y1?y20.02?0.0016??5.23 ?3?ym3.52?10G0.015??0.5m Kya0.03HOG?H?HOG?NOG?0.5?5.23?2.62m
2. 解:(1)M丙酮?58
∴ x1?6058?0.01828
6058?100018Ly1?y20.05?0.0026???2.59 Gx1?x20.01828?0由全塔物料衡算:
1m2???0.772 ALG2.59NOG???1?y?mx21?1ln??1??1??1?1A??A?y2?mx2A?
10.05???ln?(1?0.772)?0.772??7.191?0.772?0.0026?H5??0.69m 5NOG7.19G Kya∴ HOG?∵ HOG? G??VT02250273???9?2.kmol/h 022.4T22.4298∴ Kya?G92.0?0.69?5s) 0.0kmol/(m4693·
HOG?4?12?3600(2)每小时回收的丙酮量为:
G?(y1?y2)M?92.0?(0.05?0.0026)?58?252.9kg/h
3. 解:(1)y2?y1(1??)?0.06?(1?0.96)?0.0024
??L?y1?y2y1?y?G???minx1e?x?22y1m?x?0.06?0.002420.062.2?0?2.112 ∴
LG?1.2??L??G???1.?22.?1122. 5344min根据全塔物料衡算,得:
xG1?x2?L?y1?y?2?02.?15344??0.06?0.0?024?(2)
1A?mGL?2.22.5344?0.868 N?1ln??1?1??1?1?y1?mx21?OGA??y?mx?A?A??22? ?1?0.06?1?0.868ln???1?0.868?0.0024?0.868???10.81H?HOG?NOG?0.8?10.81?8.65m?8m
故此塔不能用。
4. 解:(1)D?xF?xWxF?0.4?0.1?100?37.5kmol/h
D?xW0.9?0.1 W?F?D?100?37.5?62.5 (2)对于露点进料:
V?V?F?(R?1)D?F
∵ ye?xF?0.4
0. 0227 xe?ye0.4??0.2105
??(??1)ye2.5?1.5?0.4xD?ye0.9?0.4??2.64
ye?xe0.4?0.2105∴ Rmin?R?1.5Rmin?1.?52.?64 3.96V?V?F?(R?1)D?F?4.96?37.5?100?86.0kmol/h
(3)对塔顶第一块塔板 y1?xD(全凝器)
x1?由精馏段操作线方程:
y10.9??0.7826
??(??1)y12.5?1.5?0.9y2?xR3.960.9x1?D??0.7826??0.8063 R?1R?13.96?13.96?1xF?xW0.5?0.05F??150?74.18Kmol/h
xD?xW0.96?0.055. 解:(1)由全塔物料衡算: D? W?F?D?150?74.18?75.82Kmol/h (2)∵ 泡点进料:q?1 ∴ xe?xF?0.5
ye??xe2.5?0.5??0.714
1?(??1)xe1?1.5?0.5xD?ye0.9?60.714??1.15 0ye?xe0.71?40.5∴最小回流比: Rmin?回流比: R?1.2Rmin?1.2?1.15?1.38 (3)精馏段操作线方程:
yn?1?xR1.380.96xn?D?xn??0.580xn?0.403 R?1R?12.382.38y平衡方程: x???(??1)y?y
2.5?1.5y从塔顶往下计算: xD?y1?0.96