Industrial case studies in the petrochemical and gas industry in Qatar for the utilization of industrial waste heat for the production of fresh water by membrane desalination

Abstract

An investigation into the potential of using industrial low-grade waste heat in desalination using membrane distillation (MD) has been carried out. This investigation highlighted the need to work on fresh water production using economic and environmentally friendly techniques. Using an approach based on heat integration and heat recovery principles, process streams in three industrial processes, namely the liquified natural gas (LNG), Ethylene and Vinyl Chloride Monomer (VCM) were screened to eliminate unsuitable sources of low-grade heat. This approach is appropriate to Qatar, being one of the countries that have large natural gas reserves and an emerging petrochemical industry. The criteria for selecting suitable low-grade heat sources led to the elimination of LNG and Ethylene processes for further consideration. The VCM process on the other hand showed a promising outlook, in particular in the direct chlorination section where a major vapor stream is condensed through the temperature range 118-46 C. This is precisely the ideal range for low-grade heat recovery for the MD application. A method for the implementation of low-grade heat recovered from the VCM process in a MD application was presented.