An extended energy saving method for modification of MTP process heat exchanger network

Pinch Technology has been widely adopted and considered to be one of the most successful techniques in process energy integration. But according to limitation and defect of pinch analysis in heat exchanger retrofit, a new conceptual diagram is proposed for super-ambient and sub-ambient temperature process. This diagram is based on heat flow rate as a function of temperature. By using this diagram, it can be achieve to the concepts such as: 1- retrofit of the HEN for energy saving, 2- the best location of hot and cold utility, 3- The actual amount of required hot and cold utility. Composite curve, the grand composite curve and the energy transfer diagram have been constructed for analysis of the HEN of a methanol to propylene plant. In this novel design it was attempted to improve the HEN's efficiency of MTP process and get the maximum economic return. Annual profit percentage reach to 13.2% by improving HEN via bridge method. Results showed that utilities consumption have been decreased significantly in the novel design by bridge method (about 9.3%) to pinch analysis (5.0%). Finally, it can be said, bridge analysis provides more detail about heat savings modifications, than traditional pinch analysis.