Fixed Tube Sheet Heat Exchangers
A Fixed Tube Sheet heat exchanger is the most common type of heat exchanger in all Industries. Mostly used in higher-pressure and Higher Temperature applications.
Fixed tube Sheet heat exchangers are the one that are very much used in process chemical industries and refinery services, as there is absolutely no chance for intermixing of fluids. This type of heat exchanger is employed where even slightest intermixing of fluids can not be tolerated. A fixed-tube sheet heat exchanger has straight tubes that are secured at both ends to tube sheets welded to the shell. The construction may have removable channel covers , bonnet-type channel covers , or integral tube sheets. The principal advantage of the fixe tube sheet construction is its low cost because of its simple construction. In fact,the fixed tube sheet is the least expensive construction type, as long as no expansion joint is required.
Application :
The tube sheets at both ends of the fixed tube-sheet heat exchanger are connected and fixed with the shell by means of the welding method. fixed tube-sheet type heat exchanger features simple and compact structure, and low manufacturing cost for the same diameter of shell, the biggest number of caladria is available in tubular heat exchangers is widely applied in engineering. The Fixed tube-sheet heat exchanger are that shell pass cannot be cleaned with the mechanical method and the maintenance is difficult. The Fixed tube -sheet heat exchanger is applicable to all services where the temperature difference between the shell and tube is small, the temperature difference is slightly great but the pressure of shell pass is not high with media in the shell pass not easy to scale, or the shell pass can be cleaned with chemical method after the scaling is formed.
Advantages :
Other advantages are that the tubes can be cleaned mechanically after removal of the channel cover or bonnet, and that leakage of the shell side fluid is minimized since there are no flanged joints. A disadvantage of this design is that since the bundle is fixed to the shell and cannot be removed, the outsides of the tubes cannot be cleaned mechanically. Thus, its application is limited to clean services on the shell side. However, if a satisfactory chemical cleaning program can be employed, fixed-tube sheet construction may be selected for fouling services on the shell side. In the event of a large differential temperature between the tubes and the shell, the tube sheets will be unable to absorb the differential stress, there by making it necessary to incorporate an expansion joint. This takes away the advantage of low cost to a significant extent.