THERMODYNAMIC EVALUATION OF A PROCESS PLANT

Abstract

Energy management plays key role in the economy of a process plant. Exergy analysis is relatively new energy management technique which takes into account the quality of energy and its degradation in real process. The analysis identifies avoidable as well as unavoidable irreversibilities in the various sub-regions of the plant. It helps in locating sub-regions in the plant which call for an improved operation. In the present work exergy analysis of an existing synthesis gas plant has been carried out. The irreversibilities and rational efficiencies of all sub-regions in the plant have been estimated. Results show the greatest irreversibility in the primary reformer, which is mainly due to the combustion of fuel and heat transfer across large temperature gradients .The irreversibility due to combustion of fuel is intrinsic due to uncontrolled nature of combustion process. The irreversibility of waste heat boiler after secondary reformer is quite high due to large temperature gradients between the reformed gas and steam it is shown that this irreversibility can be reduced by replacing waste heat boiler by the combination of superheater and waste heat boiler.