Page 396 - Chemical process engineering design and economics

376 Chapter 7

Table 7.5 Continued

10. Determine if Qc is sufficient from Equation 7.4.14.

11. If not, determine if the jacket + coil area is sufficient.
12. Calculate the jacket plus coil heat-transfer rate, Qj + Q c.

13. Determine if Qj + Qc is sufficient from Equation 7.4.14.

14. If not, then an external heat exchanger is necessary. The area may be estimated
from the approximate method outlined in Chapter 4.
15. Finally, calculate the mixer power, P n, by from Equations 7.4.15 and 7.4.16.

Table 7.6 Approximate STR Overall Heat-Transfer Coefficients
a
Source Ref. 7.33 ).
Coil/Agitated Liquid
Coil Side Agitated Liquid U b
Btu/h-°F-ft 2
Steam Aqueous Solution 90 - 160
Steam Organic Solution 60 - 130
Steam Heavy Oil 30-60
Hot Water Aqueous Solution 90-130
Hot Water Organic Solution 60 - 100
Cooling Water Aqueous Solution 80 - 120
Cooling Water Organic Solution 50-90
Brine Aqueous Solution 60 - 100
Brine Organic Solution 50-90
Organic Oil Heavy Organic 60-110

Jacket/Agitated Liquid

Steam Aqueous Solution 70-130
Steam Organic Solution 60-110
Cooling water Aqueous Solution 60-110
Cooling Water Organic Solution 50-80
Organic Oil c Heavy Organic 30-50

a) For additional data see Reference 11.
2
b) To convert to W/m -K multiply by 5.678.

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