低温甲醇洗工艺模拟及工况优化

发布时间：2018-05-05 23:52

本文选题：低温甲醇洗 + PSRK方程修正　；参考：《青岛科技大学》2015年硕士论文

【摘要】：低温甲醇洗工艺是一种以低温甲醇为吸收剂,通过物理吸收净化合成气中酸性组分的方法。它利用低温下CO2、H2S、H2、 CO等气体在甲醇中的溶解度差异,选择性脱除酸性气体,同时回收H2和CO。作为一种高效的气体净化工艺,低温甲醇洗在煤化工、合成氨等行业有着广泛应用。本文基于Aspen Plus软件平台,考察了低温甲醇洗系统的热力学特性,通过对比不同热力学方程对该工艺模拟的准确性,确定了PSRK状态方程的热力学方法。针对液相密度、气液两相粘度以及甲醇饱和蒸汽压等物性参数计算偏差较大的问题,通过修正缺省的物性计算路线与内置关联式,实现了合成气及低温甲醇多组分体系热力学性质的准确表征。在上述基础上,对国内某厂低温甲醇洗工艺流程进行模拟,重点研究了变换气吸收塔、非变换气吸收塔、H2S浓缩塔、热再生塔和甲醇／水分馏塔,模拟结果与实际生产数据吻合良好,最大偏差为5%,平均偏差在3%以内。对主要流股中重要组分的浓度分布情况进行了分析,符合各塔实际情况。为了实现适应市场需求的灵活生产策略,考察了变换气吸收塔等主要设备的负荷能力,对原料气中硫化物含量、贫甲醇用量、N2用量等操作条件进行了灵敏度分析,确定了在满足控制指标条件下,各操作参数的极限值。对于生产负荷提升20%的工况,通过水力学校核和分析,确定了主要塔设备的制约瓶颈,提出通过改造设计余量最小的H2S浓缩塔塔板结构来满足负荷提升的方案。本文的研究提供了准确模拟低温甲醇洗的方法,同时对生产有一定的参考价值与指导作用。
[Abstract]:Low temperature methanol washing process is a method of purifying acid components in syngas by physical absorption with low temperature methanol as absorbent. By using the solubility difference of CO _ 2H _ 2S _ 2H _ 2, CO and so on in methanol at low temperature, the acid gas is selectively removed and H _ 2 and CO _ 2 are recovered at the same time. As an efficient gas purification process, low-temperature methanol washing is widely used in coal chemical industry and ammonia synthesis industry. Based on the Aspen Plus software platform, the thermodynamic characteristics of the low-temperature methanol washing system were investigated. The thermodynamic method of the PSRK equation of state was determined by comparing the accuracy of different thermodynamic equations to the simulation of the process. In order to solve the problem that the calculation deviation of physical property parameters such as liquid density, gas-liquid two-phase viscosity and saturated vapor pressure of methanol is large, by modifying the default physical property calculation route and the built-in correlation formula, The thermodynamic properties of synthesis gas and methanol multicomponent system at low temperature have been accurately characterized. On the basis of the above, the process flow of methanol washing at low temperature in a domestic plant was simulated, with emphasis on the study of a shift gas absorption tower, a non-shift gas absorption tower, a H _ 2S condenser, a thermal regeneration tower and a methanol / water fractionator. The simulation results are in good agreement with the actual production data, the maximum deviation is 5 and the average deviation is less than 3%. The concentration distribution of important components in the main stream is analyzed, which accords with the actual conditions of each tower. In order to realize the flexible production strategy to meet the market demand, the load capacity of the main equipment such as the shift gas absorber was investigated. The sensitivity analysis of the operating conditions, such as the content of sulphide in the feedstock gas and the amount of N _ 2 used for the poor methanol consumption, was carried out. The limit value of each operating parameter is determined under the condition of satisfying the control index. For the working condition where the production load is increased by 20%, the bottleneck of the main tower equipment is determined through hydraulics check and analysis, and the scheme is put forward to meet the load lifting by modifying the H2S concentrator tray structure which has the minimum allowance. The research in this paper provides an accurate simulation method for methanol washing at low temperature, and has certain reference value and guiding function for production at the same time.
【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ028.2

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