Power generation and cooling capacity enhancement of natural gas processing facilities in harsh environmental conditions through waste heat utilization

Most natural gas (NG) producers in the Persian Gulf face increasing challenges in meeting their domestic gas demands and therefore seek to reduce their NG consumption. Concurrently, the on-site power generation and cooling capacities of local NG processing facilities are constrained by extreme climatic conditions. A combined cooling and power scheme based on gas turbine (GT) waste heat-powered absorption refrigeration is techno-economically assessed to reduce the NG consumption of a major gas processing plant in the Persian Gulf. The scheme utilizes double-effect water-lithium bromide absorption refrigeration activated by steam generated from GT exhaust gas waste heat to provide both GT compressor inlet air and process gas cooling. Based on a thermodynamic analysis, recovery of 150MW of GT waste heat is found to enhance the plant cooling capacity by 195MW, thereby permitting elimination of a 32.6MW GT and existing cooling equipment. On-site power generation is enhanced by 196GWh annually through GT compressor inlet air cooling, with energy efficiency (i.e., 64%) improved by 35% using cogeneration relative to the existing power generation plant. The overall net annual operating expenditure savings contributed by the combined cooling and power system are of $US13 million to 34 million based on present and projected local utility prices, with an economic payback period estimated at 2 to 5years. These savings translate to approximately 94 to 241MMSCM of NG per year, highlighting the potential of absorption refrigeration to both enhance the power generation and cooling capacity of hydrocarbon processing plants exposed to harsh environmental conditions and to realize substantial primary energy savings.