加油站气液比检测方法及其影响

Test method of air to liquid volume ratio and its influence in service station

气液比(A/L)是加油站油气回收系统的一项重要控制指标,利用A/L测试仪、光离子化VOCs检测仪和油气排放因子测试装置,研究了不同A/L检测连接方式对A/L检测结果、检测人员暴露浓度、油气排放和油气回收效率等的影响。结果表明,不同连接方式和是否预先向检测油桶注油会导致A/L检测结果不一致,如果油桶与流量计不连接,A/L检测值将是实际A/L的1.04倍,当按照A/L=1.00~1.20调整加油枪A/L时,实际A/L将在0.96~1.15之间;按照国标GB20952-2007连接方式检测A/L可以减少检测过程中约80%的加油油气排放,夏季检测人员暴露油气浓度将由451×10-6(体积浓度)下降至91×10-6(体积浓度),油气排放因子将由1 056 mg/L下降至242 mg/L,更可减少因油罐吸入空气造成额外的汽油挥发排放,但不能减少倒油油气排放。

Air to liquid volume ratio(A/L) is an important controlling index of vapor recovery system of the service station. We used the A/L tester,photoionization detector of VOCs,and test devices of vapor emission factor to study the impact of the A/L tester's different connection modes on the A/L test results,exposure concentration of testers,vapor emission and vapor recovery efficiency. The results showed that different connection modes and whether pre-refueling to the test tank would cause different A/L test results. If test tank and flow meter are not connected while testing A/L,detected A/L value would be 1. 04 times that of the actual value,and the actual A/L value would be between 0. 96 and 1. 15 if adjusting the A/L of nozzle in the range of 1. 00 to 1. 20. Testing A/L with GB 20952-2007 connecting method can reduce the vapor emission by approximately 80%,the vapor exposure concentration of testers in summer would decrease from 451 × 10-6to 91 × 10-6,and the vapor emission factor would decrease from 1 056 mg/L to 242 mg/L. Further more,the extra gasoline evaporating emission caused by inhaling air into the gasoline storage tank can also be reduced without reducing the vapor emission of pouring oil.