EXERGY ANALYSIS OF CHEMICAL LOOPING PROCESS

Abstract

A model for the methane cracking chemical looping combustion is developed in ASPEN PLUS V8.6 software. Chemical looping combustion has an advantage of better carbon capture efficiency. The exergy analysis is done for the whole process through HSC CHEMISTRY 9 software and also the exergy destruction is calculated for each device for the given operating values given in the previous literature. The results calculated were compared with the literature results. The next part includes the optimization which is done through DESIGN EXPERT software. Optimization is done for the fuel reactor and the air reactor i.e. the chemical looping combustion unit. For the fuel reactor exergy analysis is done by varying the input variables of the reactor i.e. temperature, pressure and NiO/CH4 ratio to a certain range. The results showed that high temperature of about 700 ℃, a low pressure of 1.65 and a molar flow ratio of 4 will give the minimum exergy destruction which is desirable. High CO2 and H2O production is desirable in the fuel reactor case. After that the output of the fuel reactor is fixed which comes through the optimum points calculated through the software. The input variables of the air reactor for a certain range is then varied with respect to the output which is exergy destruction. A little high temperature of 900℃, high pressure value of 4.8 and a Ni/Air ratio of 1.9 will favour the nickel oxide reaction which is taking place in the air reactor. Minimum exergy destruction is obtained for this value also which is desirable