| dc.description.abstract | A Hysys simulation of a CO2 capture process by absorption in a monoethanol amine (MEA) solution from the flue gas from a 500 MW natural gas power plant has been developed as a verification of earlier simulations at TUC. The major improvements in this work are new calculation methods for make-up water and MEA and simulation of a direct contact cooler (DCC) unit. For cost estimation purposes, calculations of overall heat transfer coefficient and correction factor for heat exchangers have been performed. On the basis of the base case simulation output, installed cost estimates for equipment have been made. Only equipment related to flue gas cooling and the CO2 absorption and regeneration process have been included in the simulation and cost estimation scope. Variation in cost changes has been monitored when changing process parameters like minimum approach temperature in the lean/rich heat exchanger, absorber packing height, absorber gas feed temperature. The parametric studies have been performed for CO2 removal efficiencies of 80, 85 and 90 %. In most of the calculations, one meter of packing was specified with a Murphree efficiency of 0,15. When optimizing feed gas temperature, a temperature dependent efficiency was used. The base case with an CO2 removal efficiency of 85 % has been estimated with a specific energy consumption of 3,61 MJ/kg CO2, and equipment installed cost is estimated to 1400 MNOK. The annual operational utility cost has been found to be 203 MNOK, where 61 % is related to steam consumption in the desorber reboiler. The amine package in Aspen Hysys with Kent Eisenberg was used. The Li-Mather model was checked for comparison with the base case, this resulted in a 1,5 % increase in the annual operational utility cost and 0,8 % increase in the equipment installed cost. Parametric studies at a CO2 removal efficiency of 85 % have resulted in optimum minimum approach temperature in the lean/rich heat exchanger between 10-14 K, absorber packing height 15 m, and absorber feed gas temperature approximately 40 0C. At 90 % efficiency the effect of varied process parameters is greater then at 85 %. Economic parameters like uptime and calculation period also influence on the optimum parameters. This study shows how significant process parameters are to overall cost of CO2 capture. Major improvements in cost savings can be made by optimization. Aspen Hysys is a suitable tool for such calculations. | |
