加气站LNG低温储罐液位计比选及优化方案

Comparison and optimal scheme of level gauge for low-temperature LNG tank in gas filling station

加气站LNG低温储罐液位多采用差压式液位计进行计量,无法准确测量储罐液位,从而无法对LNG的真实库存和损耗情况做出科学和准确判断,更不能真正实现LNG的库存和损耗管理。为了解决LNG低温储罐使用环境下出现的压力波动、液体饱和状态变化等因素而导致计量偏差较大的问题,介绍了多种适应LNG低温介质的液位计的测量原理及组成,探讨了常见的探头类型、仪表安装方式和注意事项,比较其性能优缺点。最后,提出采用LNG储罐安装改进后的伺服液位计的工艺方案,可以实现LNG储罐的精准计量、安全操作,解决了天然气加气站行业中低温储罐计量难题。

In gas filling stations, pressure differential level gauge is often used to measure the level of low-temperature LNG tank, which, however, fails to provide accurate results. In this case, actual stock and loss of LNG can not be estimated rationally and accurately, to say nothing of corresponding LNG stock and loss management. In order to address huge error in measurement due to the pressure surge and change of liquid saturation state when LNG tank is used, principles and components of several level gauges which adapt to low-temperature LNG medium are presented. Common types of probes, installation of devices and precautions are discussed. Advantages and disadvantages of such gauges are compared. Finally, the optimized scheme of installation of servo-level gauge on LNG tank is put forward, which can achieve the accurate measurement and safe operation of LGN tank, thereby removing the difficulties in measuring low-tempera^re tanks in gas filling stations. （2 Figures, 3 Tables, 11 References）