天然气深冷装置投产前循环干燥技术的应用

Application of circulating drying technology before puttinginto operation of natural gas cryogenic unit

目的塔里木油田天然气乙烷回收工程的部分系统设计压力达到8.0 MPa,采用水压试验模式,以保证工程施工过程中管线设备强度试压安全。为避免水压试验装置运行冻堵,保证装置顺利试车及长期平稳运行,需要高效完成天然气深冷回收装置投产前的干燥操作。方法在较全面地调研分析目前国内天然气深冷装置普遍采用的干燥方法及其存在不足的基础上,对塔里木油田天然气乙烷回收工程的循环干燥工艺技术进行优化改进。结果经过装置后期投产运行检验,优化后的循环干燥工艺流程的干燥效果好,实现了干燥气体“近零排放”,有效避免了装置水压试压后的冻堵问题。结论①即使采用气压试验装置,建议投产前同样要开展系统干燥工作;②结合工程实践情况,明确了循环干燥压力、流量、温度、水露点检测等参数确定原则;③针对实践中存在的不足,提出了切实可行的解决措施及建议,可为其他天然气深冷装置的干燥操作和相关设计提供参考。

Objective The design pressure of partial system of natural gas ethane recovery project in Tarim oilfield reaches 8.0 MPa,and hydraulic pressure test mode is adopted to ensure the safety of pipeline equipment strength pressure test in the construction process.In order to avoid freezing and blocking of hydrostatic test unit and ensure smooth test run and long-term stable operation of the unit,it is necessary to efficiently complete the drying operation of the gas cryogenic recovery unit before it is put into operation.Methods On the basis of a comprehensive investigation and analysis of the drying methods commonly used in domestic natural gas cryogenic units and their shortcomings,the cyclic drying technology is optimized and improved in the natural gas ethane recovery project of Tarim oilfield.Results After the later commissioning and operation test of the device,the fumble cycle drying technology has good drying effect,and the"nearly zero discharge"of drying gas is realized,the freezing and blocking problems after the hydraulic pressure test of the device are effectively avoided.Conclusions(1)Even if the pneumatic test device is used,it is recommended to carry out the system drying before production;(2)Based on engineering practice,the determination principles of parameters such as cyclic drying pressure,flow rate,temperature and water dew point detection are defined;(3)In view of the shortcomings existing in practice,practical solutions and suggestions are put forward,which can provide reference for drying operation and related design of other natural gas cryogenic units.