Settings for the tube side and shell side
Thread Content
Yesterday, I discussed the issue of ammonia coolers with my colleagues: In a typical ammonia synthesis unit (at 32 Mpa), the ammonia synthesis gas flows through the inner tube side of the ammonia cooler, while liquid ammonia flows through the outer shell side. My colleagues believe this arrangement is mainly due to the large evaporation area available for the liquid ammonia on the shell side; however, I think it is primarily because the pressure of the ammonia synthesis gas is high (32 Mpa) whereas the pressure of liquid ammonia is low (1.6 Mpa). Having the synthesis gas flow through the inner tube side helps to reduce the thickness of the shell of the ammonia cooler, thereby lowering the cost of manufacturing the equipment. By extension, the layout of the waste heat boiler tubes and the shell-side fluid is also determined by the costs associated with equipment manufacturing. To spark discussion, in your opinion, what are the main factors taken into consideration when determining the media for the equipment’s shell and tube sides? Safety, evaporation space, cost, heat transfer coefficient, or...? :loveliness:
In most cases, it is determined through comprehensive consideration.
The ammonia synthesis gas in question has high pressure and a fast flow rate; using it in the tube side facilitates heat transfer. Liquid ammonia, on the other hand, has lower pressure and a slower flow rate, so it is more suitable for use in the shell side where flow can reach turbulent conditions, thereby aiding heat transfer. In my opinion, the choice between tube side and shell side actually depends on many factors, as mentioned by the person above – factors such as the corrosiveness of the medium, its viscosity, and flow rate, all of which affect heat transfer