Operating pinch point analysis and bypass optimal control of heat exchanger networks
Pinch design method of heat exchanger networks(HEN)can be done for a specific operational condition,however the operational condition always fluctuates in a certain range.During practical process operation,it is often difficult to implement optimal control,since operating pinch point and the minimum temperature difference deviate from the design values.Therefore the study of pinch technology and the bypass optimal control of HEN have caught more attention,but integration of pinch technology with HEN optimal control is still not well established.The operating pinch point was studied for a given HEN,and the change of operating pinch point was qualitatively analyzed.Bypass optimal control was proposed and the bypasses were placed around the operating pinch point.Through the bypass optimal control of HEN,to which pinch point technology was applied,the total utility cost was minimized,and at the same time the commands on control performance could be reached,which was shown by the simulation of a heat exchanger network.