Abstract: It is one of the requirements to ensure an oil storage tank equipped with breather valves for limiting its vented oil-gas capacity and keeping it in safety. As the variations of physical parameters caused with the time by surroundings of the oil storage tank, the uncertainty of the design of breather valves is increased. There are many physical parameters affecting the gas flow rate through valves. Temperature change is a main factor. Based on temperature variations, a new method, peak mass conversation(PMC), was presented to calculate the gas flow rate through breather valve. The method is referred to the mass change process of both gas phase and liquid phase as an independent mass conservation, taken the gas phase component of the conservation as a research object, and determined its peak gas flow rate under the saturated vapor pressure as the gas flow rate through breathing valve. By applying the principle of mass conservation, the formula for calculating gas flow rate through breather valve was obtained. Compared to the common methods, the PMC is helpful to get actual values as well as improves the accuracy of breather valve design and selection.

Key words: oil storage tank, breather valve, tank temperature, tank pressure, flow rate, peak mass conversation

摘要： 呼吸阀是减少油气排放量、保证储油罐使用安全性的必要措施之一.由于储油罐所处环境条件的不同,罐内物性参数随时间而发生变化,增加了呼吸阀设计条件的不确定性.影响呼吸阀气通量的各种物理量是多种多样的,其中温度变化是影响呼吸阀气量的主要因素之一.本文以温度变化作为研究呼吸阀气通量的出发点,提出了新的呼吸阀气通量计算方法——峰值守恒法.即将气相与液相的质量变化过程视为一个独立的质量守恒体,把该守恒体的气相介质分量变化过程作为研究对象,并设定其饱和蒸气压状态下的峰值变化过程为呼吸阀气通量,利用质量守恒原则,推导出了呼吸阀气通量计算方法.该方法与目前常用的公式方法相比,其计算气通量更接近实际情况,提高了呼吸阀的设计与选用的准确性.

关键词: 储油罐, 呼吸阀, 油罐温度, 油罐压力, 气通量, 峰值守恒法