Abstract: The accurate measurement of boiler drum liquid level and the prevention of liquid level exceeding the limit are important prerequisites to ensure the stable operation of the boiler and affect the safety of the device. The balance vessel type differential pressure liquid level gauge is often used to measure the boiler drum liquid level in oil refining unit. Based on the measurement principle of the balance vessel and the physical characteristics of saturated water and saturated steam in the boiler drum, the defects of the balance vessel that is easily affected by the ambient temperature and cannot be measured under all working conditions are analyzed. This paper introduces the measuring principle of multi-stage capacitance level gauge. From the point of view of preventing common cause failure of similar instruments, it is suggested that the multi-stage capacitive liquid level gauge with automatic compensation function be used as an effective supplementary means for boiler drum liquid level measurement in oil refining unit.

Key words: oil refining unit, boiler drum, liquid level measurement, balance vessel, capacitance level gauge

摘要： 精准测量锅炉汽包液位，防止液位超限，是保证锅炉平稳运行、装置安全的重要前提。炼油装置中常采用平衡容器式差压液位计测量锅炉汽包液位。基于平衡容器的测量原理及锅炉汽包中饱和水及饱和蒸汽的物理特性，分析了平衡容器易受环境温度影响、无法全工况测量的缺陷。文中介绍了多段式电容液位计的测量原理，从防止同类仪表共因失效的角度出发，建议将带自动补偿功能的多段式电容液位计作为炼油装置中锅炉汽包液位测量的补充手段。

关键词: 炼油装置, 锅炉汽包, 液位测量, 平衡容器, 电容液位计