大型合成氨厂循环水系统水锤分析

摘要

The cooling water system plays an important role in large scale ammonia plant,which is related to the safe and stable operation of the whole plant.It has the characteristic of large pipe size, long pipe length and complex pipe network.Therefore,water hammer phenomenon is easy to happen in transient conditions. In order to ensure the safe and stable operation of the system, water hammer analysis is carried out in different transient conditions in this article,the opening and closing time of check valve at outlet of cooling water pump is taken as variables, and the critical system pressure and maximum pump reverse speed are investigated when the transient condition occurs. The results show that increasing the opening and closing time of check valve at outlet of pump can reduce the system pressure fluctuation, and the pump reverse speed increases with the increase of valve closing time. Furthermore, when the opening time of check valve at pump outlet is between 10-40s,the closing time of check valve at motor driven pump outlet is between 10-30s and the closing time of check valve at steam driven pump outlet is between 20-30s,the system transient pressure can be reduced below the design pressure,and the safe operation of the system can be guaranteed.%循环水系统在大型合成氨厂中具有重要的作用,关系到全厂的安全稳定运行.该系统具有管径大、管道长及管网复杂等特点,在瞬态工况下容易发生水锤现象.为了确保系统的安全稳定运行,以循环水泵出口止回阀的打开和关闭时间作为控制参数,对该系统进行了不同瞬态工况下的水锤分析,重点考察瞬态工况发生时系统出现的极限压力及泵的最大反转转速.结果表明,增加泵出口止回阀的打开和关闭时间能减缓系统内压力波动,泵的反转转速随着关阀时间的增加而增加.当泵出口止回阀打开时间为10~40s,电驱泵出口止回阀关闭时间为10~30s,汽驱泵出口止回阀关闭时间为20~30s时,可以将系统瞬态压力降低到设计压力以下,保证系统的安全运行.