LNG工厂混合冷剂液化工艺冷箱提量研究

Study on cold box lift of mixed refrigerant liquefaction process in LNG plant

关键词:  混合冷剂  冷箱  提量调整  换热

摘要:

为了研究LNG工厂混合冷剂液化方式的运用及调整情况,以湖北500×10⁴ m³/d LNG工厂国产化示范工程实际生产情况(400×10⁴ m³/d提至500×10⁴ m³/d)为例,收集提量期间各测点温度、混合冷剂组分变化、差压变化、操作调整等数据进行综合分析。分析结果表明:湖北500×10⁴ m³/d LNG工厂兼具传统阶式制冷循环与混合冷剂制冷循环优点,在系统稳定性与可调节性能上均具优势,在冷箱换热不均的情况下仍可正常生产；但提量前系统中就出现冷剂混合不均、冷箱出现两相流等情况,提量中虽进行降量复热、曲线提产等操作,同时也针对性地进行提高压缩机转速、优化BOG放空等措施来提高系统稳定性,但都不能彻底弥补冷剂混合不均所带来的影响。因此,提量期间各个阶段都应制定切实可行的预案,并且做阶段性验证。 

Abstract:

In order to study the way of mixed refrigerant liquefaction situation and its adjustment in LNG plant, taking the actual production conditions of Hubei 5 million cubic meters/day LNG plant localization demonstration project (from 4 million cubic meters/day to 5 million cubic meters/day) as an example, the data about each measuring point temperature changes, mixed refrigerant components, differential pressure, and adjusting operation collected from the quantity improving were analyzed comprehensively. The results showed that:5 million cubic meters/day LNG plant in Hubei combined traditional cascade refrigeration cycle with mixed refrigerant refrigeration cycle, which has advantages both on the system stability and adjustability. In the case of uneven heat transfer of cold box, the plant can still operate normally. However, before improving quantity the system occurs uneven cooling mixing and two phase flow in the cold box, etc. During improving quantity, although taking the measures of dropping amount and recovering heat, raising production by curves, and improving rotating speed of compressor and optimizing BOG for enhancing the system stability, the influence by uneven refrigerant mixing cannot be solved entirely. For this reason, we should made the feasible plans and the periodic verification at the each stage during improving quantity.