中国首套LNG液力透平系统开发与工业化测试

天然气液化装置中采用低温液力透平替代传统LNG或MR混合冷剂J-T节流阀实现节流降压是提高天然气液化装置效率的先进技术,也是全球天然气液化技术发展的一种趋势。我国目前已拥有超过136座的天然气液化工厂,但尚未实现低温液力透平的国产化和工业化应用。为此,通过对LNG液力透平工艺及控制系统开发、本体水力模型优化设计、样机结构设计与制造等关键技术进行攻关,开发了国内首套LNG液力透平系统(设计流量为40 m3/h),用于回收LNG冷箱出口LNG压力能。LNG液力透平系统在中海石油广东液化天然气有限公司天然气液化装置完成了系统启停、变流量、变转速多工况工业化测试。测试结果表明:1样机本体运转平稳,低温机械性能良好,运行性能参数基本达到设计预期;2工艺及控制系统、变频发电系统设计可行,可与已有天然气液化装置上的LNG产品J-T节流阀自动平稳切换使用,平均可提高LNG产量2%,发电8.3 k W。

Development and industrial tests of the first LNG hydraulic turbine system in China

The cryogenic hydraulic turbine can be used to replace the conventional J-T valve for LNG or mixed refrigerant throttling and depressurization in a natural gas liquefaction plant. This advanced technology is not only to enhance the efficiency of the liquefaction plant, but to usher a new trend in the development of global liquefaction technologies. China has over 136 liquefaction plants, but the cryogenic hydraulic turbines have not been deployed in industrial utilization. In addition, these turbines cannot be manufactured domestically. In this circumstance, through working on the key technologies for LNG hydraulic turbine process & control system development, hydraulic model optimization design, structure design and manufacturing, the first domestic cryogenic hydraulic turbine with a flow rate of 40 m³/h was developed to recover the pressure energy from the LNG of cold box. The turbine was installed in the CNOOC Zhuhai Natural Gas Liquefaction Plant for industrial tests under multiple working conditions, including start–stop, variable flow rates and variable rotation speeds. Test results show that the domestic LNG cryogenic hydraulic turbine has satisfactory mechanical and operational performances at low temperatures as specified in design. In addition, the process & control system and frequency-conversion power-generation system of the turbine system are designed properly to automatically and smoothly replace the existing LNG J-T valve. As a result, the domestic LNG cryogenic hydraulic turbine system can improve LNG production by an average of 2% and generate power of 8.3 kW.