TABLE OF CONTENTS Up to this chapter, attention has been given to mass integration. As mentioned in Chapter One, there are two main commodities handled in the process: mass and energy. Both contribute to the overall performance of the process and both affect the capital and operating costs of the process. Heat is one of the most important energy forms in the process. The current chapter provides an overview of heat integration. First, the problem of synthesizing networks of heat exchangers is discussed while highlighting the analogy with synthesizing networks of mass exchangers. Next, targeting procedures are presented with the objective of minimizing heating and cooling utilities while maximizing heat exchange among the process streams.
In a typical process, there are normally several hot streams that must be cooled and several cold streams that must be heated. The usage of external cooling and heating utilities (e.g., cooling water, refrigerants, steam, heating oils, etc.) to address all the heating and cooling duties is not cost effective. Indeed, integration of heating and cooling tasks may lead to significant cost reduction. The key concept is to transfer heat from the process hot streams to the process cold streams before the external utilities are used. The result of this heat integration is the simultaneous reduction of heating and cooling duties of the external utilities.
The problem of synthesizing HENs can be stated as follows:
Given a number N H of process hot streams (to be cooled) and...
