天然气发热量间接测量不确定度评估方法再探——参比条件下天然气压缩因子不确定度评估

Further discussion on uncertainty evaluation of indirect measurement of natural gas calorific value:uncertainty evaluation of compression factor under reference condition

关键词:  天然气发热量  间接测量  参比条件下压缩因子  求和因子  不确定度评估 

Key words:  calorific value of natural gas  indirect measurement  compression factor under reference condition  summation factor  uncertainty evaluation

摘要:

前期的研究表明,参比条件下压缩因子不确定度是天然气发热量间接测量不确定度评估过程中引入的一个不确定度来源,并且其不确定度贡献较大。同时,参比条件下的压缩因子不确定度在天然气体积计量等过程中也有所使用。通过对参比条件下压缩因子的计算过程进行分析和推导,获取了参比条件下压缩因子不确定度评估公式,结合各类参考文献,分别对各类不确定度来源做A类或B类评估,形成了一套用于参比条件下压缩因子不确定度的评估方法。通过对天然气组成不确定度变化对参比条件下压缩因子不确定度的影响核算,发现天然气组成不确定度的变化对参比条件下压缩因子不确定度影响较小,超过20倍的组成不确定度变化仅引起压缩因子不确定度数值上的变化。 

Abstract:

The uncertainty of compression factor on reference condition is a big source to the uncertainty evaluation of indirect calorific value measurement according to the earlier study, it contributes a lot to the uncertainty of calorific value. On the other hand, the uncertainty of compression factor on reference condition is also applied in the volumetric measurement of natural gas. The calculation formula of natural gas is analyzed and derived in order to get the evaluation formula of compression factor. With the help of reference article, the uncertainty source is evaluated as type A or type B uncertainty. These two steps make a whole procedure to the uncertainty evaluation of compression factor on reference condition. The influence of different uncertainty of composition on the uncertainty of compression factor is tested by simulative calculation. With difference orders of magnitude composition uncertainty, compression factor uncertainty comes out to be quantitative.