Dry gas cleaning process by adsorption of H_2S into activated cokes in gasification of carbon resources

摘要

Gasification of carbon resources including biomass and coal is one of promising energy production technologies. The R&D on effective and convenient gas cleaning processes for removal of contaminants as well as high efficient reliable gasifiers is essential for industrial application in broad fields. In this study, a dry process of synthesis gas cleaning by adsorption of H_2S into activated cokes was proposed as a candidate of desulfurization technologies in gasification. The H_2S adsorption performance of activated coke produced from coal, which are used industrially for de-SO_x and de-NO_x, was evaluated by the thermogravimetric analyses and the adsorption examination in a fixed bed under the atmospheric and high pressures. Activated coke was not only the most active at about 423 K for the H_2S adsorption rate but also regenerative over 573 K by H_2S desorption with a sufficient rate under an inert gas flow of nitrogen. The H_2S adsorption performance of the activated coke was not inhibited by the co-existence of CO_2 or COS but enhanced rather by the co-existence. The adsorbent was promisingly active for both H_2S and COS adsorption as well. These behaviors suggest that the activated coke are available for simultaneous desulfurization of H_2S and COS. The H_2S breakthrough examination in the fixed bed revealed that it was possible to remove H_2S to lower level than 1 ppm for a long time depending on the residence time of gas flow in the bed. When the adsorption operation was carried out under high pressures up to 0.6 MPa, the regeneration of activated coke by H_2S desorption took place under the pressure reduced to the atmosphere. As the results, it was implied that the present activated coke could be applicable to the desulfurization process in coal gasification.