Thermodynamic assessment of a novel combined cycle to provide the power of the refrigerated warehouse and eliminate the environmental emissions

One of the city gate stations in Tabriz, Iran, which has a capacity of 120,000 SCMH, has been investigated in this research. Energy recovery has been achieved by replacing pressure reduction equipment with a turbo-expander for generating electrical power. The research's innovations include completely eliminating the preheater as a source of natural gas combustion, which eliminates the CO2 emissions and produces refrigeration load from the natural gas's recovery energy. Alongside this station, a refrigerated warehouse has been set up, utilizing its condenser as a preheater for natural gas before it enters the turbo expander. The proposed system produces 9.34 GWh of electrical energy yearly through the turbo-expander, with 4.32 GWh allocated to the refrigerated warehouse compressor and 5.02 GWh supplied to the power grid. The cash generated from electricity sales to the power grid totals $903,600, while the economic savings from stopping electricity purchases for the compressor of the proposed system reach $777,600. The reduction in natural gas consumption resulting from the elimination of the preheater at the CGS station totals 63.4 × 103 m3, corresponding to an annual economic value of $114,597. The total elimination of CO2 emissions by the proposed system is estimated to be around 9,503 tons annually. This action will thus remove around $855,270 in yearly penalties for CO2 emissions. The maximum refrigeration load of the refrigerated warehouse is established at 490.63 TR, and the maximum exergy efficiency is computed at 28.04%.