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.

► Feasibility study on application of AHP (Adsorption Heat Pump) to Ethylene process was conducted.
► The propylene refrigerant for the ethylene process was partially replaced by ChW (Chilled Water) from the AHP.
► The AHP was operated by utilizing low temperature waste heat sources of the process for the desorption step of water vapor from the adsorbent of the AHP.
► The required power for PRC (Propylene Refrigerant Compressor) of the process got down 10% by partially replacing the refrigerant by the ChW.
► The ChW was utilized for Depropanizer condenser and CGC (Charge Gas Compressor) 5th stage chiller as cooling source.