AM-08-75 Refinery Off Gas Treatment and Recovery – Challenges of Designing ROG Units

Description:

Refinery off-gas (ROG) is produced in the refinery units that manufacture conversion products such as hydrotreaters, alkylation units, FCC, and Platformers. Valuable products including hydrogen, olefins, natural gas liquids (NGL) and higher Btu fuel gas can be recovered from the off-gas if a ROG processing unit is installed. The incremental economics of product recovery as opposed to using the entire off-gas for fuel provides the incentives for installation of ROG units. The composition of the refinery off-gas stream will vary appreciably depending on the source. The refinery off-gas may contain a number of trace components such as oxygen, ammonia, nitriles, acetylenes, sulfur compounds, butadiene, chlorides, arsenic, mercury, and water in addition to acid gases H2S, CO2, and COS. The specifications of the recovered products and catalyst requirements will dictate the allowable limits of these contaminants in the feed stream Methods for removal of the individual contaminants in the off-gas are detailed in the paper. Various configurations of the ROG plant and associated units are compared depending on the type of product and feed stock. Optimization strategies required for the design are also discussed in the paper.