Page 72 - Process Equipment and Plant Design Principles and Practices by Subhabrata Ray Gargi Das

CHAPTER

4
Shell and tube heat exchanger

4.1 Introduction
Shell and tube exchangers are the most common equipment in process industries for heat transfer
betweenflowingfluidstreams.These canhave heat transfer area ranging from 0.1 to 100,000 m 2
and can be used over a wide range of pressure and temperature conditions ranging from vacuum to
2
1000 kg/cm pressure and from cryogenic temperature to 1000 C. In addition, these can be

fabricated using a wide range of materials and are suitable for high pressure operations. Ease of
cleaning enables their usage for dirty fluids and slurries. They also provide a relatively larger heat
2 3
transfer surface per unit volume and weight (typically 50e100 m heat transfer area per m of
equipment volume) and require a minimum number of connections. Well-established design pro-
cedure and fabrication techniques make these exchangers versatile for a wide range of applications,
namely (i) steam generators, condensers, boiler feed water heaters and oil coolers in power plants;
(ii) condensers and evaporators in air conditioning and refrigeration applications and (iii) waste
heat recovery and heating and cooling applications involving process liquids and gases/vapours
with and without phase change. They can also be designed for special operating conditions like
vibration, heavy fouling, highly viscous fluids, erosion, corrosion, toxicity, etc. Nevertheless, they
are not normally used in automotive and aircraft applications because of their relatively large size
and weight.

4.1.1 General description
The major components of a shell and tube exchanger are shell, front end head, rear end head, baffles,
tubes and tube sheet. The tube sheet assembly comprising of tube bundle, baffles, tie rods, and spacers
is fitted in the exchanger shell and closed at the ends with heads.

Shell
Shells are available with inside diameters up to 3 m ð120 Þ. Shells with 610 mm ð24 Þ or
00
00
lower diameters are generally made from steel pipes, while larger sizes are made from rolled steel
plates.
Exchanger Head(s)
Inside the shell, the tubes are arranged in a bundle and held in place by a pair of header plates (tube
sheet). One end has a tube sheet fixed to the shell. This is the stationary tube sheet and the head

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