PDF《对天然气推荐性国家标准 GB/T 31253 的讨论》

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87 ・ 对天然气推荐性国家标准 GB/T

31253 的讨论 周理1,2,3 陈赓良

2 郭开华

1 1.

中山大学工学院 2. 中国石油西南油气田公司天然气研究院 3. 中国石油天然气质量控制和能量计量重点实验室 摘要2014 年发布的推荐性国家标准 天然气 气体标准物质的验证 发热量和密度直接测量法 GB/T

31253 是以 ISO/TR

24094 技术报告为基础、以修改采用的方式编制而形成的.基于对上述 ISO 技术报告的分析,认为 GB/T

31253 在确认方法、气体标 准物质确认程序等方面存在着一些问题并对其进行了讨论和质疑.研究认为 : ① ISO/TR

24094 的标题宜修改为 天然气分析― ―气 体标准物质的确认方法 ,该技术报告不宜转化为推荐性国家标准 ;

② VAMGAS 研究项目使用的

2 个多元标准气体混合物是以称量 法制备的基准级标准气混合物(PSM) ,使用的参比热量计(或密度天平)也必须是基准级的,其测量不确定度应优于 0.1%,这样 才能合理地与 PSM 进行统计比较 ;

③水流式热量计测量天然气发热量的扩展不确定度仅为 1.0%(k=2) ,不能作为天然气发热量测 定的基准仪器 ;

④天然气能量计量涉及气体体积流量计量、直接法和间接法测定天然气发热量等

3 种计量技术,其量传、溯源方式、 不确定度评定方法及其适用标准各不相同 ;

⑤ GB/T

31253 及其附录中存在着一系列的计量技术规范(JJF)及标准的误用问题,因 而其附录 B、D、E 皆不能成立.最后建议 : 撤销 GB/T 31253,将ISO/TR

24094 以等同采用的方式转化为指导性国家标准. 关键词 天然气 能量计量 直接法测定发热量 间接法测定发热量 溯源性 化学计量溯源性

0 级热量计 不确定度评定 DOI: 10.3787/j.issn.1000-0976.2017.12.014 A discussion on the Chinese national standard GB/T 31253: From Recommendatory (GB/T) to Guidance (GB/Z) Zhou Li1,2,3 , Chen Gengliang2 &

Guo Kaihua1 (1. Faculty of Engineering, Sun Yat-Sen University, Guangzhou, Guangdong 510006, China;

2. Natural Gas Research Institute of PetroChina Southwest Oil &

Gas Field Company, Chengdu, Sichuan 610213, China;

3. CNPC Key Labora- tory of Natural Gas Quality and Energy Measurement, Chengdu, Sichuan 610213, China) NATUR. GAS IND. VOLUME 37, ISSUE 12, pp.87-91, 12/25/2017. (ISSN 1000-0976;

In Chinese) Abstracts: The recommendatory national standard GB/T

31253 Natural Gas C Validation methods for gaseous reference materials (RGM) -Calorific value-Density direct measurement method issued in

2014 was compiled and modified from the ISO/TR

24094 standard. Based on the analysis of ISO/TR 24094, we made a discussion and presented some queries on the existing problems in the aspects of determi- nation methods, RGM validation procedures, etc. The following results were concluded. (1) The keyword of validation in the ISO/TR

24904 should be better interpreted as a confirmation method and this international standard is not proper for being transformed as a recommendatory national standard in China. (2) Two multiple reference air mixtures (RAMs) in the VAM Gas Standards Project are made from the primary standards materials (PSMs) by the weighting method, the referenced calorimeter (or density balance) should be in the reference level, and its uncertainty of measurement should be at least bigger than 0.1%, then it will be much more reasonable to refer to or compare with the PSM. (3) The expanded-standard uncertainty of the calorific capacity of a natural gas water-flow calorimeter?is only 1.0% (k=2) can not be taken as the primary standard measuring device. (4) Natural gas energy metered by the volumetric flowrate, direc- tion and indirect methods will be varied by different quantity-transfer, traceability modes, uncertainty determination and adaptable stan- dards (codes). (5) Some misuse problems have been found in the technical specifications JJF of the GB/T