摘要
含硫天然气的泄漏会造成人员中毒,严重威胁管道附近人员的生命安全,ASME标准中推荐的潜在影响半径计算模型不适用于含硫天然气管道。常用气体扩散模型忽略泄漏气体的喷射作用导致中毒影响半径计算结果过于保守,因此首先分析含硫天然气管道泄漏特点,考虑泄漏气体喷射高度和泄漏速率的变化对硫化氢地面体积分数的影响,基于天然气泄漏扩散规律建立了不同时刻烟团和烟羽体积分数叠加表征的硫化氢中毒潜在影响半径R计算模型。考虑截断阀紧急关闭影响,按照30 s时间提出了泄漏速率分段计算依据,并合理确定了瞬时泄漏气团质量Q、连续性泄漏源强q、扩散参数以及泄漏气团中心高度H等基本参数。针对不同压力、管径、硫化氢体积分数条件,进行了中毒影响半径、热辐射潜在影响半径及忽略喷射高度的影响半径对比分析,合理提出了按照中毒潜在影响半径确定含硫天然气管道潜在影响半径的计算方法。
The present article is inclined to offer a model we have developed for calculating the impact of the potential poisoning radius in ASME B31 on the leakage of the acidic natural gas in the pipe. As is known,since the current model for doing such calculations recommended in the ASME standard proves not to be suitable for its being a bit too conservative due to its main concern about the natural gas dispersion rather than the poisoning radius.Therefore,it is necessary to analyze first of all the particular features of the natural gas pipeline and the R radius effects of the hydrogen sulfide poisoning while full attention has to be paid to the hydrogen sulfide concentration of the discharging height and the variation of the discharging rate of the pipeline. It is just on the aforementioned basis that we have developed a method for determining the acidic natural gas pipeline potential impact radius. To build up the said model,we have first of all analyzed the characteristics of the acidic natural gas pipeline discharge and dispersion. Based on the natural gas dispersion law,we have established a potential poisoning radius calculation model while considering the effects of the emergent releasing height and the variation of the releasing rate on the hydrogen sulfide concentration. To determine the chief parameters of the model,we have attributed the atmospheric stability to class A. At the same time,taking into careful account the cut-off emergency shutdown effects,we have segmented all the calculating pipeline releasing rates in a period of time of 30 seconds. Later,we have also defined the instantaneous release mass Q and the continuous release accidence strength q reasonably by working out the releasing rate of the pipeline in different cases. With all the rest basic parameters determined,such as the flow coefficient and the central height of the release puff H in accordance with the relative literature,we have finally determined the potential poisoning radius,the thermal radiation potential impact radius and the jet height-neglected impact radius while a comparison is made between the pipe diameters and hydrogen sulfide content at the different pressures. Thus,it can be seen that this study presents a reasonable way for calculating the acidic natural gas pipeline potential affecting radii in accordance with the potential poisoning radius. Thus,it is certain that the model we have developed for calculating the impact of the potential poisoning radius in ASME B31 which can serve as a reasonable reference for establishing a innovated identification method for the gas pipeline risk-zone consequence area.
引文
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