Energy saving for ethylene process by Adsorption Heat Pump

The Ethylene production plant is one of the most important plants in the petrochemical industry. The process requires a huge amount of low temperature cooling but at the same time it discharges a large amount of low temperature heat. This low temperature heat source can be utilized to run an Adsorption Heat Pump (AHP) for chilled water (ChW) generation, or for direct process cooling. In this paper, a process integration study is performed that applies an AHP to partially replace some of the cooling loads in the propylene refrigeration system that is a part of the cooling system in an ethylene process. This integration successfully reduces the overall compressor power of the propylene refrigerator by 10%. Other potential benefits are also reported, along with the capital investment and pay back time of the heat integration project. The potential modifications identified in this study include utilizing the chilled water (ChW) generated by AHP for both the depropanizer condenser and the charge gas chiller at the 5th stage of the charge gas compressor (CGC). If the modification of the depropanizer condenser was applied to all the ethylene plants around the world, a reduction in emissions of 4.6 Mt of CO2 could be made each year.