Page 114 - Process Equipment and Plant Design Principles and Practices by Subhabrata Ray Gargi Das

4.7 Design illustration 111

Table 4.19 Nozzle thickness.
Nominal nozzle Corrosion allowance
size, mm (in.)
w1mm w3mm w6mm
00 Sch. 160
25:4ð1 Þ

38:1 1 1 00
2
Sch. 160 Sch. 160
00
50:8 ð2 Þ
00
76:2 ð3 Þ
Sch. 80
00
101:6 ð4 Þ
00
152:4 ð6 Þ
00
203:2 ð8 Þ
00
Sch. 80
254 ð10 Þ
00
304:8 ð12 Þ
Sch. 80
00
355:6 ð14 Þ
00
406:4 ð16 Þ
Sch. 40
00
457:2 ð18 Þ
Sch. 40
00
508 ð20 Þ
00
609:6 ð24 Þ
4.6.12 Exchanger support
Horizontal exchangers require saddle support which is designed as per the appropriate code of design for
unfired pressure vessels, i.e., IS 2825 for India, ASME code for TEMA exchangers or other codes that
may be mutually agreed by the manufacturer and the purchaser. When more than one shell is used, these
are usually stacked to reduce floor space requirement and also to keep the connecting piping short.
4.7 Design illustration
3
Design a shell and tube heat exchanger to cool 55 m /hr of light kerosene (55 API) from 130 Cto 50 C

using cooling water available at 33 C. Maximum return temperature of cooling water can be 45 C.

2
2
Cooling water supply header pressure is 4 kg/cm (g) and the return header pressure is 2.5 kg/cm (g).
2
Supply pressure of kerosene is 6 kg/cm (g). Maximum allowable total pressure drop for either flow is
2
0.7 kg/cm .
Collect rest of the fluid properties from literature. All other data can be taken from TEMA code or
the corresponding IS code. Intermixing of the codes needs to be avoided.
Solution: In this heat exchanger, hot fluid is kerosene and cold fluid is water. The thermal condition
is depicted in Table P4.1. Properties are evaluated at average temperatures as kerosene is a light
hydrocarbon with low viscosity, its viscosity variation with temperature is not drastic and also the
temperature range of water is fairly limited.
Since this is an illustrative example, sticking to a specific design code has not been adhered to. The
reader is advised to refer to the original document of any of the codes, generate the design and compare
the results with those presented.