Description

Many different exchanger configurations can be easily created by different combinations of front end, shell and rear end. Moreover, depending on how tube bundle is fixed to the front end or rear end cover, we have 3 broad types of shell & tube heat exchanger construction. Fixed Tube sheet Exchanger A fixed-tube sheet heat exchanger has straight tubes that are secured at both ends to tube sheets welded to the shell.The main advantage of the fixed tube sheet exchanger is its low cost because of its simple construction. Fixed tube sheet being the least expensive shell & tube exchanger type, as long as we don't use any expansion joint. But for the same reason, fixed tube sheet exchanger does not help much for services having large temperature difference between shell & tube sides. Because in such cases, an expansion joint would be needed. Other advantages are that the tubes can be cleaned easily by removing the channel cover or bonnet. Moreover, absence of flanged joints helps to minimize the leakage of the shell side fluid. But there is a disadvantage that the outsides of the tubes cannot be cleaned mechanically, as the tube bundle is fixed to the shell. Fixed tube sheet exchangers require that a clean fluid must be used on the shell side.When you have a dirty fluid on tube side, you may consider this type of exchanger. U tube exchanger As the name suggests, in this type the tube bundle is U shaped. Features:-Strong construction -Optimum quality-Durable finish standard The advantage of using a U tube bundle is that the tubes can freely expand as they are U turn end of the bundle is freely floating in the shell side. Hence a U tube exchanger is the preferred option where there is high temperature difference between shell & tube side fluids and tube expansion is expected. These exchangers are also cost effective, as expansion joints are not needed and tube bundle is free to expand. Floating head exchanger In this type of shell & tube exchanger, one end of the tubes is kept fixed in a tube sheet attached to the shell side. While the other end is free to expand or 'floating' in the shell side. But as the same time, this U shape of the tubes makes it difficult to mechanically clean them. Only chemical cleaning would be possible. Hence U tube exchangers are normally not preferred where we need to use a dirty or fouling service on the tube side. Applications:- Refineries-chemical industry-off shore Activities-Petrochemical industry -Pharmaceutical Industry-Food Processing Industry