天然气液化用拉伐尔管结构设计数值模拟分析

Numerical simulation on structure design of Laval nozzle used in natural gas liquefaction

拉伐尔喷管是天然气超音速液化分离管的核心部件,对制冷和分离效果具有重要影响。采用Fluent软件对天然气超音速液化拉伐尔喷管结构设计进行数值模拟,分析了渐扩段尺寸和渐缩段线型对天然气降温效果及气流运动规律的影响。结果表明,渐扩段锥度减小导致天然气不完全膨胀,将减少温降,不利于制冷;锥度过大导致天然气过度膨胀,压降过大,不利于旋流分离;渐缩段采用维托辛斯基曲线可以保持气流较好的均匀性,有利于气液分离。

As the core component of natural gas supersonic swirling separator, Laval nozzle has an important influence on the refrigeration and separation. Fluent software was used to simulate the structure design of Laval nozzle for natural gas supersonic liquefaction. The influences of the expanding section size and the reducing section line shape on the cooling effect of natural gas and the law of airflow movement were analyzed. The results show that small taper of divergent section will cause incomplete expansion of natural gas, which will reduce the temperature drop and is bad to refrigeration. Larger taper of divergent section will cause excessive expansion of natural gas and larger pressure drop, which is bad to cyclone separation. The Vitosinsky curve in the reducing section can maintain better gas flow uniformity.