A HEAT INTEGRATION STUDY CONSIDERING VARIABLE PHYSICAL PROPERTIES

Abstract

The technology of energy integration is an outstanding approach for reducing the consumption of energy and increases the profit throughout the process. Due to continuous increase in the cost of energy and depletion of conventional resources of energy also day by day growing environmental problem there are strict need of to reduce the energy consumption by improving the existing process. In refineries except the cost of crude, energy took huge sum of money which can be modified if a better design being presented and has therefore become our focus. Lots of technique has been presented for the study of heat exchanger network problems like tree searching, mixed integer non linear programming, genetic algorithm, graphical method. Pinch technology also called graphical method. In all these method this work is limited to pinch technology because it is the most notable method in all method due its easy technique and robustness. In pinch technology the physical properties are taken as constant but in reality physical property especially heat capacity is a function of temperature which has significant effect on the design of heat exchanger network. So to show the temperature dependency of streams three problems have been taken and pinch technology has been applied. First two problems are formulated problem and the third one is industrial problem of sponge iron industry. First two problems have two hot and two cold streams while the problem 3 has four cold and four hot streams. Energy, area, no. of unit, cost and super targeting have been performed first by taking constant heat capacity and then by variation in heat capacity for all the three problems. It has been seen that for the problem 1 when consider variation in physical property both utility increases but area decreases, overall total annual cost increases. The same trend are observe in problem 2 and problem 3, which shows that by considering the variation in CP increases utility so it should be kept in mind while designing the heat exchanger network. Also the final design of HEN is presented for all the three problems taken so