HEAT AND POWER INTEGRATION IN A CHEMICAL PLANT

Abstract

In the present investigation, heat and power integration has been carried out in a nitric acid plant, with the aim of utilizing the waste heat in the process and to simultaneously increase the work generation from the process. Usually in a chemical plant, the steam provides the main utility in the process, so the emphasis has been placed on the utility placement. Pinch design method has been used for the appropriate utility placement in the process, which results in the modifications of the base case process. It has been observed that, in all the modified cases, waste heat has been utilized successfully to increase the work generation; hence the goal of heat and power integration has been achieved successfully. The thermodynamic analysis has been carried out with the aim of reinforcing the design decisions made by pinch technology and to identify the various exergy losses occurring in the process. Exergy analysis has helped to locate the irreversiblities occurring in the process due to reaction as well as due to heat transfer. The irreversibilities due to spontaneous reaction are inevitable. Therefore an attempt has been made through pinch technology to reduce the avoidable irreversiblities occurring in the heat transfer system. It has been found that the modified cases suggested by the pinch technology have also achieved higher rational efficiency, ensuring that the heat and power integration has been successfully carried out in the nitric acid plant.