A feed of 4360 kg/h of a 20wt % NaOH solution in water at 37.8°C enters continuously a single-effect evaporator and is being concentrated to 40%. The evaporation is at a pressure of 12.349 kPa (abs) and the heat transfer coefficient is 1560 W/(m²K). Saturated steam at 232.1 kPa (abs) is supplied for heating. (vapour heat capacity is 1.884 kJ/kg/K). a) Calculate the heat transfer area and the steam economy. b) For all operation conditions remain unchanged and the heat transfer coefficient is constant, if the evaporation pressure is decreased, what will the evaporator size change? Give the justification. c) For all operation conditions remain unchanged and the heat transfer coefficient is constant, if the steam pressure is decreased, what will the evaporator size change? Given the justification
A feed of 4360 kg/h of a 20wt % NaOH solution in water at 37.8°C enters continuously a single-effect evaporator and is being concentrated to 40%. The evaporation is at a pressure of 12.349 kPa (abs) and the heat transfer coefficient is 1560 W/(m²K). Saturated steam at 232.1 kPa (abs) is supplied for heating. (vapour heat capacity is 1.884 kJ/kg/K). a) Calculate the heat transfer area and the steam economy. b) For all operation conditions remain unchanged and the heat transfer coefficient is constant, if the evaporation pressure is decreased, what will the evaporator size change? Give the justification. c) For all operation conditions remain unchanged and the heat transfer coefficient is constant, if the steam pressure is decreased, what will the evaporator size change? Given the justification
Introduction to Chemical Engineering Thermodynamics
8th Edition
ISBN:9781259696527
Author:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Publisher:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Chapter1: Introduction
Section: Chapter Questions
Problem 1.1P
Related questions
Question
Please answer the whole question 3 a - b - v

Transcribed Image Text:Question 3
A feed of 4360 kg/h of a 20wt % NaOH solution in water at 37.8°C enters
continuously a single-effect evaporator and is being concentrated to 40%. The
evaporation is at a pressure of 12.349 kPa (abs) and the heat transfer
coefficient is 1560 W/(m²K). Saturated steam at 232.1 kPa (abs) is supplied for
heating. (vapour heat capacity is 1.884 kJ/kg/K).
a)
b)
Calculate the heat transfer area and the steam economy.
For all operation conditions remain unchanged and the heat transfer
coefficient is constant, if the evaporation pressure is decreased, what will
the evaporator size change? Give the justification.
c)
For all operation conditions remain unchanged and the heat transfer
coefficient is constant, if the steam pressure is decreased, what will the
evaporator size change? Given the justification

Transcribed Image Text:A.2-9 Properties of Saturated Steam and Water (Steam Table), SI Units
Specific Volume
(m²/kg)
Temper- Vapor
ature
Pressure
(°C)
(kPa)
0.01
3
69NEREZONASIN
12
15
18
21
24
25
27
30
33
36
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
125
130
135
'140
145
150
155
160
165
170
175
180
190
200
225
250
275
300
120.82
143.27
169.06
198.53
232.1
270.1
313.0
316.3
415.4
475.8
543.1
617.8
700.5
791.7
892.0
1002.1
1254.4
1553.8
2548
3973
5942
8581
Sat'd Vapor
0.0013168
0.0010436
Enthalpy
(kJ/kg)
Liquid
Sat'd Vapor Liquid
0.0010002
206.136
0.00 2501.4 0.0000
9.1562
12.57 2506.9 0.0457
9.0773
25.20 2512.4 0.0912
9.0003
8.8524
37.80 2517.9 0.1362 8.9253
50.41
2523.4 0.1806
62.99 2528.9 0.2245
75.58 2534.4 0.2679
88.14 2539.9
8.7814
8.7123
0.3109
8.6450
100.70 2545.4 0.3534 8.5794
104.89 2547.2 0.3674
0.6113
0.7577 0.0010001 168.132
0.9349 0.0010001 137.734
1.1477 0.0010003 113.386
1.4022 0.0010005 93.784
1.7051 0.0010009 77.926
2.0640 0.0010014 65.038
2.487 0.0010020 54.514
2.985 0.0010027 45.883
3.169 0.0010029 43.360
3.567 0.0010035 38.774
4.246 0.0010043 32.894
5.034 0.0010053 28.011
5.947 0.0010063 23.940
7.384 0.0010078 19.523
9.593 0.0010099 15.258
12.349 0.0010121 12.032
9.568
7.671
6.197
5.042
113.25 2550.8 0.3954
125.79 2556.3 0.4369
138.33 2561.7 0.4781
2567.1 0.5188
15.758
19.940
0.0010146
0.0010172
150.86
167.57 2574.3 0.5725
188.45 2583.2 0.6387
209.33 2592.1 0.7038
230.23 2600.9 0.7679
251.13 2609.6 0.8312
272.06 2618.3 0.8935
292.98 2626.8 0.9549
313.93 2635.3 1.0155
25.03
0.0010199
31.19
0.0010228
38.58
0.0010259
4.131
3.407
47.39
0.0010291
334.91 2643.7 1.0753
57.83
0.0010325
2.828
355.90
2651.9 1.1343
70.14
0.0010360
2.361
376.92
2660.1 1.1925
84.55
0.0010397
1.9819
397.96
2668.1 1.2500
101.35
0.0010435
1.6729
419.04
2676.1 1.3069
0.0010475
1.4194
440.15
2683.8 1.3630
0.0010516
1.2102
461.30 2691.5 1.4185
0.0010559
1.0366
482.48
2699.0 1.4734
7.1833
0.0010603
503.71 2706.3 1.5276
7.1296
0.0010649
0.8919
0.7706
0.6685
524.99 2713.5
1.5813
7.0775
0.0010697
546.31 2720.5 1.6344
7.0269
0.0010746
0.5822
567.69 2727.3
1.6870
6.9777
0.0010797
0.5089
589.13 2733.9 1.7391
6.9299
0.0010850
610.63 2740.3 1.7907
6.8833
0.0010905
632.20 2746.5 1.8418
6.8379
0.0010961
653.84 2752.4 1.8925
6.7935
0.4463
0.3928
0.3468
0.3071
0.2727
0.2428
0.0011020
675.55 2758.1 1.9427
6.7502
0.0011080
697.34 2763.5 1.9925
6.7078
0.0011143
719.21 2768.7 2.0419
6.6663
0.0011207
0.2168
741.17 2773.6 2.0909 6.6256
0.0011274
0.19405 763.22 2778.2 2.1396 6.5857
0.0011414
0.15654
0.0011565
0.12736
0.0011992
807.62 2786.4 2.2359 6.5079
852.45 2793.2 2.3309
6.4323
966.78 2803.3 2.5639 6.2503
1085.36 2801.5 2.7927 6.0730
5.8938
0.07849
0.05013
0.03279 1210.07 2785.0 3.0208
0.02167 1344.0 2749.0 3.2534
0.0012512
5.7045
Liquid
Entropy
(kJ/kg-K)
Sat'd Vapor
8.5580
8.5156
8.4533
8.3927
8.3336
8.2570
8.1648
8.0763
7.9913
7.9096-
7.8310
7.7553
7.6824
7.6122
7.5445
7.4791.
7.4159
7.3549
7.2958
7.2387
Source: Abridged from I. H. Keenan, F. G. Keyes, P. G. Hill, and J. G. Moore, Steam Tables-Metric Units. New York: John Wiley & Sons,
Inc., 1969. Reprinted by permission of John Wiley & Sons, Inc.
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