THERMODYNAMIC ANALYSIS OF SULPHURIC ACID PLANT

Abstract

Energy conservation is a key goal of our economy now and will continue to be so in the future as well. The most effective way to reduce energy demand is to use energy more efficiently which in turn, emphasizes the need for an appropriate energy management technique. It is now established that the appropriate technique should take into account the differentiation among various grades or qualities of energy, which are otherwise neglected the conventional energy balances. A universal standard of quality of energy is exergy. This thesis presents a theoretical investigation on thermodynamic analysis of sulphuric acid plant, using the concepts of exergy. Degradation of energy in various processes is expressed in terms of irretrievable loss of exergy. Thus the relative values of irreversibilities and exergies at various locations in the plant demonstrate the degradation of energy sequentially. This is represented quite vividly through the Grassmann diagram. The significant aspects of the sulphuric acid plant are two types of exothermic reactions releasing large quantities of thermal energy, which is used partly for internal processes while the remainder is employed fdr external applications as process steam. Hence the total exergy output of the plant comprises the exergy of the process steam and that of sulphuric acid produced. Since the magnitudes of both the components, in exergy terms are comparable, their production should be properly integrated for high overall plant rational efficiency, Computations show that the sulphur burner incurs the largest irreversibility, which is mostly intrinsic in nature, due to the uncontrolled nature of the oxidaion reaction. The irreversibilities in different converter passes though intrinsic, are relatively small. The irreversibilities in other sub-regions of the plant, associated with heat transfer, can be reduced through better process integration. (