Shell and tube heat exchanger is the heat exchanger type that is most widely used in industrial process. This is because the type of shell and tube can be used for processes with large range of variations in pressure and temperature. In addition, another advantage of shell and tube heat exchanger type is can be constructed with wide range of material variations. Shell and tube heat exchanger can be divided into three main types. The composition of shell and tube heat exchanger type is conventionally classified according to nomenclature of Tubular Exchanger Manufacturers Association (TEMA).
The three classifications of tube and shell heat exchanger as following below:
- Fixed Tubesheet Type of Shell and Tube Heat Exchanger
This type is very modest when compared with the two next types. The characteristic of fixed tubesheet type is the presence of fixed or stationary tubesheet. In terms of maintenance, mechanical or chemical method can be applied to the inner side of pipe. Mechanical method is done by using cleaning brush, while chemical method uses chemical liquid that is sprayed into pipe. The difficulty will occur is if there is crust, scale, or deposit attached on on the outside of pipe, so the cleaning method cannot be performed because construction of fixed tubesheet will not allow technician clean the crust from the outside.
The disadvantage of fixed tubesheet type is it cannot resist high thermal expansion that will cause leak on the side of tubesheet. Therefore, this heat exchanger type is not recommended for use at too high temperature. The addition of expansion space is needed to overcome thermal expansion problem.
- U - Tube Type of Shell and Tube Heat Exchanger
U - Tube has form that is not too complex like fixed tubesheet type so that the cost of manufacture is not too expensive. This heat exchanger type has U-shaped pipe. The advantage of this type is the ease of maintenance at the outside of pipe by remove tube bundle. After tube bundle are removed from shell, the mechanical cleaning on the outside of pipe or on the side of shell can be easily done.
In contrast to U-shaped pipe, the cleaning by mechanical method is quite difficult for the inside of pipe due to due to the U-bend causes scrubber brush can not reach this part. Furthermore the cleaning method is more recommended to use chemical liquid. Another advantage of this type is thermal expansion will occur on the side of pipe bend so it can resist thermal expansion well.
- Floating Head Type of Shell and Tube Heat Exchanger
This heat exchanger type has most complex arrangement when compared with the previous two types. This is because of floating head cover that causes the cost of manufacture is more expensive. Floating head type is very appropriate when working at high pressure and temperature condition. The existence of thermal expansion will be received by floating head cover. Tube bundle of heat exchanger consists of straight pipe arrangement which is strongly installed on the edges.
Tubesheet diameter on the inlet side of fluid has larger diameter than the diameter of shell, whereas on the other side, the tubesheet diameter has smaller dimension than the diameter of shell. The purpose of election of this configuration is to make easy for move in translational if thermal expansion occur on the side of floating head cover. The maintenance at the isnside and outside of pipe can be done easily. Maintenance for outside pipe can be done by removing tube bundle while for inside pipe can be carried out by using scrubber brush or chemical liquid.