Absorption-compression hybrid refrigeration analysis and application for energy conservation of cryogenic separation in propane dehydrogenation

Cryogenic separation is an energy extensive process in chemical industries and compression refrigeration (CR) is the most common refrigeration technology with huge energy consumption and carbon emission. Based on the principle and thermodynamic analysis of absorption refrigeration (AR) and CR, this paper puts forward serial AR-CR combined absorption-compression hybrid refrigeration (ACHR) technology as a substitution for traditional CR to conserve both power consumption and carbon emission. Industrial propane dehydrogenation is employed and the ACHR is introduced to accomplish the cryogenic separation by refrigerating temperature and load division. The phase transition of refrigerated streams encompassed by AR is crucial to the performance of ACHR. When the inter-connected temperature is determined to be 6 °C, the optimal refrigeration scenario is obtained. Through partial substitution of AR driven by waste heat for CR, the results show that the hybrid refrigeration can save 48.73% of power consumption and 110.8 GW h of energy per year, which is equivalent to the annual reduction of 39.8 kt standard coal and 0.12 Mt carbon emission. This work demonstrated that absorption-compression hybrid refrigeration is prospective in energy consumption and emission reduction industrially.