低温甲醇洗亏冷原因分析及应对措施

Analysis of reasons of loss of cooling energy in rectisol process and coping measures

为了分析300 kt/a合成氨装置低温甲醇洗冷量亏损原因,将低温甲醇洗系统看成一个整体,对照设计进行全局性冷量平衡分析,找出影响冷量平衡的因素,逐项分析、验证、排除,找到冰机制冷效果差、贫甲醇冷却器换热效果差、冷区保冷效果差、抽氢气改造设计缺陷、硫化氢浓缩塔气提效果差等问题,采取更换换热器、更新保冷、增设冷量回收换热器、增设氮气气提塔等一系列有效应对措施,消除低温甲醇洗亏冷现象,使得低温甲醇洗生产负荷恢复到设计水平,不再成为合成氨装置的生产瓶颈,实现了企业节能降耗、提质增效的目标。本次采取的全局冷量平衡分析方法是一种全局、系统、有效分析问题的工具,分析问题全面准确,不容易丢项,可为同行业提供参考。

The reasons for the loss of cooling energy in rectisol plant were found out in 300 kt/a synthetic ammonia unit by analyzing the cool energy balance of the rectisol system according to the initial design.The relevant factors of influencing the cool energy balance were analyzed,verified and excluded item by item.Then some problems in the synthetic ammonia unit were found,including the poor cooling effect of the ice mechanism,the low heat transfer effect of the lean methanol cooler,the unsatisfactory performance of cold zone insulation,the lower gas extraction effect of hydrogen sulfide concentration tower and the design defects of hydrogen pumping plant and so forth.In view of these problems,a series of effective measures have been taken to improve the situation,such as replacing heat exchanger,renewing cooling protection,and adding cooling recovery heat exchanger and nitrogen gas lift tower and so on.The results show that the rectisol capacity is restored to the initial design level,and is no longer a bottleneck for synthetic ammonia unit.The goal of energy saving,consumption reduction,quality improvement and efficiency improvement.The systematic and entire analysis method of cooling energy balance adopted in this paper is an efficient analysis tool to exactly diagnose the loss of cooling energy in rectisol process,providing a reference for the industry.