改性UDS溶剂提高天然气中甲硫醇脱除效率的研究

采用量子化学计算方法优选对甲硫醇具有高效吸收溶解性能的活性组分,并设计与原UDS溶剂进行复配,获得改进的UDS复合脱硫溶剂。测定甲硫醇(MeSH)在改进前后2种UDS溶剂中的溶解平衡行为,考察各溶剂对MeSH的溶解性能。研究改进后UDS溶剂的热稳定性及抗发泡性能。在常压吸收实验装置上对比考察改进前后UDS溶剂对模拟川西海相气田高酸性天然气的吸收净化效果。结果表明:聚乙二醇二甲醚(PEGDME)与MeSH分子间的相互作用力最强,是提高MeSH吸收溶解性能的适宜组分;改进后UDS溶剂对MeSH较原UDS具有更高的平衡溶解度。改进后UDS溶剂具备良好的热稳定性能及优异的抗发泡性能,可以满足天然气净化脱硫工艺的要求。在常压、吸收温度为40℃、气液体积比为360的吸收操作条件下,改进后UDS溶剂对MeSH的脱除率较原UDS溶剂提高10.3百分点,总有机硫脱除率提高5.7百分点,净化气中总硫浓度由70.0mg/m~3降低至54.1mg/m~3,产品气质量由国标二类气升级至一类气。采用改进后UDS溶剂处理以甲硫醇为主要有机硫的高酸性天然气,将有助于降低产品气总硫含量,提高产品气质量。

STUDY OF IMPROVING MeSH REMOVAL EFFICIENCY BY MODIFIED UDS SOLVENT FROM NATURAL GAS

The active component that can enhance the adsorption for MeSH was successfully screened by applying quantum chemistry computation method and then was formulated mixed with the original UDS solvent to obtain a modified high efficiency UDS solvent. The equilibrium solubilities of MeSH in the original UDS solvent and the updated solvent were investigated and compared. In addition, the thermal stability and anti-foaming performance of both UDS solvents were evaluated. The absorption experiments were conducted in an atmospheric unit using simulated Chuanxi natural gas as raw material. The results indicate that polyethylene glycol dimethyl ether (PEGDME) has the strongest intermolecular interaction with MeSH molecule, therefore, is expected to be the promising component for improving the removal of MeSH. As compared with the original solvent, the improved UDS solvent shows a higher solubility of MeSH and has a better thermal stability and anti-forming performance. The modified solvent has 10.3 percentages higher removal rate of MeSH and the total sulfur content decreases in purified gas from 70.0 mg/m3 to 54.1 mg/m3, 5.7 percent points higher than original one at the adsorption conditions of gas/liquid volume ratio of 360 and absorption temperature 40 ℃, and atmospheric pressure. The gas quality is improved from the national standard II to the top one.