An algorithm for optimal waste heat recovery from chemical processes

• Waste heat recovery from chemical processes.
• Steam-raising using the pinch concept.
• Computational algorithm for maximum energy recovery.

We describe a computer algorithm designed to calculate the optimal energy extraction in the form of heat used for steam raising from chemical processes. The concepts are illustrated using chemical plant stream data in a process with multiple distillation columns. Pinch analysis is first applied to find the grand composite curve (GCC) of the problem, which is then used by the algorithm to determine the maximum mass flow rate of steam that can be produced from process waste heat. An analysis of the effects of the minimum temperature of approach ΔTmin on the optimal steam raising result is also conducted, and it is found that, in general, a higher ΔTmin will reduce the percentage heat recovery from the process.