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中小城镇是我国当前天然气利用快速发展的区域,工程设计中其天然气管网多采用中压A级配气管网,而忽略了中压B级管网具有的特性。为此,比较了中压B级和中压A级管道的爆破能量比和泄漏质量流量比,分析了压能转移利用的贡献,对中压A级管道所需的最小街道宽度进行了定量分析,论证了中压B级管道的适用性。进而用虚拟环网覆盖中小城镇供气区域,推导出等流速工况下中压天然气配气管网管径表达式,计算了相同管网构成时不同供气规模、不同最大管路长度时,中压B级管网与中压A级管网的管材耗量比。结果表明:中小城镇天然气配气管网采用中压B级比采用中压A级投资增加20%以上,经济性相对较差;但中压B级在压力安全和敷设条件方面却具有明显的优势。因此对于老城古镇等区域较窄的街道,要考虑各种方案并综合决策。结论认为:中压B级配气管网在中小城镇的应用具有广阔的前景。
Small and medium-sized towns are the regions where natural gas utilization is developing rapidly in our country. In natural gas pipeline network of engineering design, medium-pressure grade A gas distribution pipelines are mostly used, while those of medium-pressure grade B pipelines are neglected. Therefore, the ratio of blasting energy to leakage mass flow rate of medium-pressure B-stage and medium-pressure A-stage pipelines was compared, the contribution of pressure energy transfer utilization was analyzed, and the minimum street width required for medium-pressure A-level pipelines was quantitatively analyzed , Demonstrating the applicability of medium-pressure class B pipelines. Then, the virtual ring network is used to cover the gas supply area of middle and small cities. The pipe diameter formula of medium pressure natural gas distribution pipe network under constant flow rate is derived. When the same pipe network is composed of different gas supply pipelines and different maximum pipe lengths, Pressure B-level pipe network and medium-pressure pipe network A pipe consumption ratio. The results show that the gas economy of medium and small town natural gas distribution network with medium pressure B grade is more than 20% higher than that with medium pressure grade A investment, but the medium pressure B grade has obvious advantages in terms of pressure safety and laying conditions. Therefore, the ancient town of the old town and other narrow streets, to consider a variety of programs and integrated decision-making. The conclusion is that the application of medium-pressure B-class gas distribution network in medium and small cities and towns has broad prospects.