Hydrogen Pinch Analysis of Preemraff Göteborg and Preemraff Lysekil - A systematic analysis of hydrogen distribution systems
Examensarbete för masterexamen
Harder regulations regarding dearomatization and desulphurization of fuels in addition to increased yield of valuable products are making hydrogen scarce in the refinery process. Hydrogen demands not covered with gas from reforming of naphtha must be met by steam reforming. Hydrogen production from steam reforming is both costly and energy intensive, and refineries therefore aims at avoiding this. In this thesis a relatively new tool, hydrogen pinch analysis, is used to review the hydrogen distribution system of two refineries: Preemraff Göteborg and Preemraff Lysekil. The reasons for the two refineries to participate in the project have been different, but the goal on both has been to identify shortcomings of the hydrogen distribution system. Preemraff Göteborg wants to be able to run their refinery at design capacity for all units, even after a revamp has been made in order to produce renewable based diesel. Preemraff Lysekil wants to cut down on their production of hydrogen from the steam reformer. The analysis of the hydrogen distribution systems in Göteborg and Lysekil resulted in two respectively three suggestions for better hydrogen economy. This has mostly been achieved through redirection of off gases from the fuel gas net to an upgrading facility. The suggestions are all independent of each other, and have therefore been combined into a larger case covering all suggestions. At Preemraff Göteborg, fresh hydrogen to the unit not working at maximum capacity was increased by 23 % with a payback time of 1.4 years. This could be achieved via one of the presented cases, which included purchase of a new compressor. At Preemraff Lysekil, hydrogen production in the steam reformer could be lowered with 19 %, from approximately 70 100 Nm3/h to 55 600 Nm3/h. The suggestion achieving this also included a new compressor, since off gases with high purity but low pressure was found to be the most promising hydrogen source.
Kemiska processer , Chemical Process Engineering