Iron Oxide Based Desulfurizer Preparation And Its Application In Natural Gas Removing H₂S Production

With the constant further development of heavy oil in Liaohe Oilfield, the problem of oilfield associated gas containing sulfur gradually is exposed. Hydrogen sulfide（H₂S） has been found in associated gas of Block Qi-40, Shu1 area, Wa-38 block, block Jin 45 etc in Liaohe Oilfield. Hydrogen sulfide contained in associated gas will accelerate corrosion of gas transmission pipeline and related equipment and facilities, have a serious impact on the health of workers and the surrounding people, and cause serious pollution to the environment. Along with the extension of the production period of Liaohe oilfield, the H₂ S content in associated gas shows an increasing tendency, and carbonyl sulfide（COS） content gradually increases. In this paper, iron oxide-based desulfurizer was prepared with sludge containing iron in Dawn sewage treatment plant as raw material, which provides a new way for the treatment of sludge containing iron. The modification to iron oxide-based desulfurizer prepared with sludge containing iron was carried out to improve the treatment efficiency of iron oxide-based desulfurizer for removal of H₂ S and COS. Contrasted experiments on site were done in the Block Qi-40 of Liaohe Oilfield with the modified iron oxide-based desulfurizer to investigate the adaptability of operation in presence of CO₂.In the preparation process of iron oxide-based desulfurizer from iron sludge, the optional acid leaching conditions was as follows. The concentration of sulfide acid was 70%, the reaction time was 2h, the reaction temperature was 120℃, the hydrochloric acid dosage was15 ml per 10 g raw material（drier）, co-solvent dosage was 10 g per 10 g raw material（drier） and the highest iron leaching yield reached 95.19%. Claybank ordinary striped iron oxide-based desulfurizer particles were successfully prepared from iron sludge. The strength of the desulfurizer is higher than 40N/cm, the bulk density is 0.80⁰.90g/ml, the specific surface area is 50⁷0m2/g, pore rate is 39% and particle size is φ（4±0.3）×（5¹5）mm. With H₂ S concentration of feed gas of 50mg/m3, room temperature（25℃）, atmospheric pressure, space velocity of 1000h-1, water vapor content of 1% and oxygen free conditions, the breakthrough sulfur capacity of the iron oxide-based desulfurizer from iron sludge prepared in above conditions is around 34.8% and the saturated sulfur capacity is 43%.The iron oxide-based desulfurizer from iron sludge were modified through impregnation with carbonate as the active component. The optimum conditions of removing the carbonyl sulfide in natural gas on the modified iron oxide-based desulfurizer were investigated as follows. Carbonate loading of the modified iron oxide-based desulfurizer was 5%, the space velocity of feed gas was 2000h-1 and water vapor content was 1.5%. By comparing the capacity of removing H₂ S and carbonyl sulfide on unmodified and modified iron oxide-based desulfurizer, the results show that desulfurization of carbonyl sulfide on modified desulfurizer enhances greatly with an increase of sulfur capacity of H₂ S and CS2.The modified iron oxide-based desulfurizer with larger pore volume and specific surfacearea, higher purification speed and sulfur capacity, high-strength, and good water resistance,is suitable for application in high CO₂ content system. According to the inner and practical application experiments, the breakthrough sulfur capacity of desulfurizer can reach above20% and high sulfur capacity can reach more than 25%.