H2S removal with short time contactors in a pressurized black liquor gasification plant, 2010 TAPPI/PAPTAC International Chemical Recovery Conference

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Chemrec operates a pressurized black liquor gasification demonstration plant in Piteå called DP-1. The gasification of black liquor generates a synthesis gas with major components of H₂, CO and CO₂. A smaller amount (1-2%) of H₂S is also formed. There is a need to remove the H₂S before the synthesis gas can be converted to e.g. transportation fuels. Removing the H2S from the synthesis gas and feed it back to the pulp mill with the green liquor is a very interesting alternative from a sulfur recovery perspective. The synthesis gas in DP-1 can be fed to a series of 3 short time contactors (in DP-1) in which the gas can be contacted with different absorption liquids. In this work the performance of the contactors was evaluated using water, white and green liquor. The liquid flow and temperature had an effect on the removal of H₂S. Up to 78% of the H2S in the synthesis gas could be removed with green liquor in a limited number of experiments carried out during October 2009 in the demonstration plant. These results are very promising and it is believed that the system is far from optimized and further work may follow in which this will be done. Also, the effect of mill integration will then also need to be taken into further account.