LNG空温式气化器结霜机理及控制技术

Frosting Mechanism and Control Technology of LNG Air Temperature Vaporizer

分析LNG空温式气化器的结霜机理,将结霜过程分为霜晶生长期、霜层生长期、霜层充分生长期,应严格控制霜层生长期,防止气化器大面积结霜。在LNG气化站现场取样,通过实测,得到霜层孔隙率为6.13%。分析空气温度、空气相对湿度、气化器间距对气化器结霜的影响,通过实测霜层厚度,计算得出气化器霜层热阻随影响因素的变化规律,得出空气温度对气化器霜层热阻影响最大,因此要严格控制气化器周围空气温度。提出减少气化器结霜的控制措施(蒸汽加热气化器周围空气、机械排雾、气化器间距控制、SCADA智能监控),运行实践表明,采取控制措施后,有效控制了气化器的结霜现象,霜层厚度和结霜长度明显减小。

The frosting mechanism of LNG air temperature vaporizer is analyzed.The frosting process is divided into frost crystal growth period,frost layer growth period and frost layer full growth period.The frost layer growth period should be strictly controlled to prevent large area frosting of vaporizer.Sampling is taken at the LNG vaporizing station.Through the actual measurement,the porosity of the frost layer is 6.13%.The influence of air temperature,relative humidity and distance between vaporizers on the frosting of vaporizers is analyzed.Through the actual measurement of the thickness of frost layer,the variation law of the vaporizer frost layer thermal resistance with the influence factors is calculated.It is concluded that the air temperature has the greatest influence on the vaporizer frost layer thermal resistance,so the air temperature around the vaporizer should be strictly controlled.The control measures to reduce the frosting of vaporizer are put forward(using steam to heat the air around the vaporizer,mechanical mist removal,vaporizer spacing control,SCADA intelligent monitoring).The operation practice shows that the frosting phenomenon of vaporizer is effectively controlled after taking control measures,and the thickness and length of frost layer are significantly reduced.