煤制合成气中温变压吸附H_(2)/CO_(2)分离研究与示范

Study and demonstration of H_(2)/CO_(2) separation of syngas from coal by elevated temperature pressure swing adsorption

煤制合成气净化工段位于水气变换后,脱除H_(2)S、CO_(2)等气体杂质,获取较高纯度的工业H_(2)。目前成熟净化工艺为以低温甲醇洗、液氮洗为代表的湿法以及变压吸附脱碳为代表的干法技术。中温变压吸附(ET-PSA)技术在与来流变换气一致的中温温度区间运行,采用自行合成的疏水富氮活性炭吸附剂,将传统变压吸附操作温度提升至170~220℃,实现中温高湿环境下的硫碳共脱。引入N_(2)充洗和低压N_(2)清洗2个新变压吸附步序,可使H_(2)回收率提高至99%。以丰喜泉稷厂煤制变换气为中试侧线原料,搭建了原料气处理量5 000 m^(3)/h(标况下)的中温变压吸附H_(2)/CO_(2)分离中试试验装置,H_(2)经两级中温变压吸附纯度达到燃料电池H_(2)水平(含有效气N_(2)),中试装置已累计运行超过2 800 h。并以公用工程运行数据计算中试装置能耗,仅折算电耗,中试H_(2)净化运行成本相比丰喜泉稷厂内低温甲醇洗H_(2)净化电耗可节约成本约35%。该技术突破了常规固体吸附净化温度限制,采用中温下选择性吸附性能好的吸附剂实现H_(2)中杂质定向脱除,为实现高效高品质H_(2)净化提供新的工艺路线。

Purification section of syngas from coal is located after water gas shift to remove hydrogen sulfide,carbon dioxide as the main gas impurities and obtain high purity hydrogen.At present,the mature purification processes include wet method represented by low temperature methanol scrubbing and liquid nitrogen scrubbing,and dry method represented by pressure swing adsorption decarburization.The operating temperature of the elevated temperature pressure swing adsorption technology proposed is consistent with the temperature of the incoming shift gas.Self-made hydrophobic nitrogen-rich activated carbon adsorbent was deployed to achieve desulfurization and carburization by increasing the traditional pressure swing adsorption operating temperature to 170-220℃and high humidity environment.Two new PSA steps,high pressure steam rinse and low pressure nitrogen purge,were adopted to improve H_(2) recovery to above 99%.The elevated temperature pressure swing adsorption H_(2)/CO_(2) separation demonstration with a processing capacity of 5000 m^(3)/h(standard condition)was built and operated using coal based shift gas from Quanji Plant as the feedstock for the pilot plant.The purity of hydrogen reaches the hydrogen fuel level(including N_(2))through two-stage ETPSA,and the pilot plant has been running for more than 2800 hours in total.In addition,the energy consumption of the pilot plant was calculated based on the utilities expenses.When taking power consumption into consideration,the operation cost of H_(2) purification for the pilot test can be significantly reduced by about 35%compared with the power consumption of H_(2) purification by low temperature methanol scrubbing at Fengxi Plant.This technology breaks through the limitation of temperature of conventional adsorption and purification for solid adsorbents,and realizes directional removal of impurities in hydrogen by using adsorbents with preferred selective adsorption performance at elevated temperature,which confirms a new process route for efficient and high-quality hydrogen purification.