Automation of Shell and Tube Heat Exchanger using PLC

Heat exchanger is a unit operation used in many industrial processes for transfer of thermal energy. The main purpose of HE is to maintain specific temperature conditions, which is achieved by controlling the exit temperature of the process fluid in response to the variations of operating conditions. In this paper PLC control schemes to maintain exit temperature of process fluid is discussed. Here process fluid (i.e. cold fluid) temperature is maintained using hot fluid. Simple feedback temperature control loop can be implemented to regulate controlled variable i.e. outlet temperature of cold fluid with manipulation of hot fluid flow. Experimental results for more optimum control using cascade loop with temperature controller (primary feedback controller) combined with disturbance function cold fluid inlet flow controller are used to regulate the temperature of outlet fluid of shell and tube HE system to overcome due to deviations in the input fluid flow.[4].