Large heat exchangers are used in downstream petrochemical processing, for example to recover heat from a fluid that would either be cooled for its next process, or would release the heat to atmosphere as waste energy.
This heat can be used to pre-heat another fluid as part of its own process. Such an application would be the pre-heating of hydrocarbon feed stock in a refinery.
A variation on the shell and tube exchanger is its use as a condenser at the outlet of a steam turbine. In this case steam at near vacuum in the pressure vessel flows over cooling water in the tube bank to condense and be returned to the process.
Shell & Tube
Shell and Tube Heat Exchangers are the most commonly used method of transferring heat between two fluids at different temperatures in a pressurised flow. A large pressure vessel carrying one fluid contains a bundle of tubes carrying the other fluid. As they flow past each other, the thermal transfer occurs in a controlled way.