Application of exergy analysis to improve the heat integration efficiency in a hydrocracking process

Abstract

Heat integration techniques are now widely used for energy saving in petroleum processes. In this paper, an industrial hydrocracking process (UOP license) is retrofitted by pinch analysis as a significant tool for heat integration. The hydrocracking process is a main important conversion process in oil refineries and there has been sustained effort to improve its energy efficiency. Application of pinch analysis in retrofit of this process shows the heat exchanger network is operated efficiently. However, a large amount of energy is wasted from the hydrocracking unit, which their condition make no of use directly by the process during pinch analysis. Actually, most of the refining petroleum processes use considerably more energy than the operational minimum energy requirements because of their energy losses. These external energy losses are due to many factors, including normally inefficient or outdated equipment and process design, inadequate heat recovery, and poor integration of heat sources and sinks. However, without identifying the quality of the energy losses, it is difficult to determine how much of that energy is feasible to recover under realistic plant operating conditions. This is where exergy analysis can significantly assist in determining energy recovery opportunities. Thus, this paper is addressed to researchers who are assessing the quality of energy wasted in hydrocracking process, by using the principles of both pinch and exergy analysis. Based on the result obtained, the flue gas exhaust and the high pressure drop in reaction section can be considered as the exergy loss sources in this process. Moreover, the portion of waste energy that can be practically recovered is quantified.