【作者】 关威；

【导师】 张述伟；

【作者基本信息】 大连理工大学 ， 化学工艺， 2007， 硕士

【摘要】 采用煤加压气化技术生产的城市粗煤气中含有一定量的轻烃物质、二氧化碳、硫的氧化物、氨气以及苯等有害杂质，必须在并入城市煤气管网前脱除。低温甲醇洗净化法是一种典型的物理吸收净化气体中酸性组分的方法。它利用了甲醇在低温下对H₂S，CO₂等气体的吸收量大、选择性高等特点，能很好地净化粗煤气。目前国内引进的大型煤气化装置中采用低温甲醇洗方法净化的已有多套。多数装置由于扩产或原料改变都面临着改造，其中低温甲醇洗净化系统的工艺设备改造是最繁杂的任务。采用通用模拟软件实现低温甲醇洗工艺全流程模拟更是鲜有报道，在软件平台上对低温甲醇洗净化系统进行全流程模拟，有利于弄清原有系统工艺原理，进而实现改造工况各个工艺参数的研究开发，从而显著缩短方案设计时间，并达到工艺优化、节能降耗目的，因此具有重要意义。某气化厂低温甲醇洗工艺在生产中发现净化气硫含量大于1ppm，且由于原料气组成发生变化，新增加的氨气和苯对工艺影响很大，必须对现有装置及工艺流程进行改造；同时，工厂希望对低温甲醇洗工艺进行扩产改造，使生产能力提高10％。由此，本文利用通用模拟软件强大的流程模拟功能和准确的物性库，采用改进的PSRK热力学模型成功完成设计工况的全流程模拟，分析了导致净化气含硫的原因，对各个工艺参数进行优化，提出了合理的工艺改造方案和优化设计方案：采用增加水洗塔和共沸塔的方式，较好的解决了在低温甲醇洗系统内部脱除氨气和苯的问题；采用增加氮气气提塔的方法，解决了多功能吸收塔吸收能力瓶颈和H₂S浓缩塔塔顶硫含量过高问题，为工厂装置的扩产改造提供了依据。更多还原

【Abstract】 The pressurized coal gasification technology producing rough city gas leads to generate a certain amount of hydrocarbon material, carbon dioxide, sulfur oxides, ammonia, benzene and other harmful impurities, which must be cleaned up before merged into the pipeline net of coal gas. Rectisol is a typical purification method to eliminate acid components in gas by physical absorption. The advantage of its large absorption capacity and high selectivity to H₂S, CO₂ of methanol at low temperature makes Rectisol process a good purification technique in crude gas treatment.At present, there are some large coal gasification plants using Rectisol as their purifying method in China. Most plants need to be reformed for increasing capacity or to accommodate changes in the feedstock. As an important purification part of gasification plants, the Rectisol process is usually the most complicate unit to be reformed. However, it is seldom reported by using universal simulation software to simulate the whole process. Therefore, if Rectisol process is simulated and analyzed by simulation software, technology support for existed process revamp and new process development of the Rectisol process in large scale purification plants can be provided.During the operation of a gasfication plant, many problems occur including the over limited sulfide existing in purified gas and tail gas in the rectisol process, as well as great detriment to the rectisol due to the existence of ammonia and benzene newly-added in the feed stocks. Meanwhile, the factory hopes to expand its productivity by 10%. Therefore their equipments have to be revamped in the light of great change in feed stack and for other purposes. Presently, the universal simulation software is applied, and an ameliorate PSRK thermodynamic model is adopted based on the powerful functions and an accurate property database. All kinds of units are connected step by step until the simulation of the whole flowsheet is completed. Moreover, the simulation results of all output streams had better accordance with the corresponding design data by all means. At last, the reasons for occuring over limited sulfide in purified gas are analyzed and the technologic parameters are optimized, with reasonable transformation of the program etc. Several revamp measures are proposed based on the successful simulation analysis of the design case. By introducing the azeotropic water tower and water wash tower into the process, the ammonia and benzene existed in the orginial Rectisol are efficiently gotten rid of; By newly adding a nitrogen gas stripper column, the bottlenecks of gas absorption capacity and H₂S concentration in tail gas are erased, providing necessary technical support and theoretical guidance for the transformation of the plant, as well as a reference for the revamp of similar units.更多还原