摘要
目的 天然气掺氢是大规模、长距离输氢的有效方式,但高压掺氢天然气在放空过程中,由于压力、温度、化学反应和静电摩擦等多种因素的作用而存在自燃风险,因此,对掺氢天然气放空自燃条件进行分析.方法 基于流体力学、化学反应和电场理论,建立了放空过程流场、温度场、化学反应和电场耦合模型,研究了模型解耦求解算法;以西气东输一线管道某阀室放空管道为对象,分析了掺氢比、放空管内径、放空立管高度和放空压力对自燃的影响.结果 掺氢比、放空管内径、放空立管高度与放空压力增大均会导致放空管各区域内气体最高温度升高与OH-质量分数增大,而水平管长度对气体温度与OH-质量分数无显著影响;在最接近自燃的放空工况下,气体温度与OH-质量分数均未达到自燃条件.结论 该阀室放空管道在现有的设计及运行条件下放空掺氢天然气时,不具备发生自燃形成稳定燃烧火焰的条件.
Abstract
Objective Doping hydrogen into natural gas pipelines is an effective way to transport hydrogen on a large scale and long distances.However,during the venting process,high-pressure hydrogen-doped natural gas poses a risk of spontaneous combustion due to various factors such as pressure,temperature,chemical reactions,and electrostatic friction.Therefore,the conditions leading to spontaneous combustion during the venting process of hydrogen-doped natural gas were analyzed.Methods Based on fluid mechanics,chemical reactions,and electric field theory,a coupled model of the flow field,temperature field,chemical reaction field,and electric field for venting hydrogen-doped natural gas was established,and the model decoupling solution algorithm was studied.Then,taking the venting system of a valve chamber in the West-East Gas Pipeline as an example,this study analyzed the effects of hydrogen doping ratio,inner diameter of vent pipe,height of vent riser,and vent pressure on spontaneous combustion.Results The increase in hydrogen doping ratio,inner diameter of the vent pipe,height of the vent riser,and vent pressure not only leads to the rising of maximum temperature but also promotes the increase of OH-mass fraction,while the length of the horizontal pipe has no significant effect on gas temperature and OH-mass fraction.In addition,even under the most prone conditions to spontaneous combustion,the gas temperature and OH-mass fraction have not reached the spontaneous combustion criterion.Conclusion Under the existing design and operation conditions of the valve chamber venting system mentioned above,hydrogen-doped natural gas venting does not have the conditions for spontaneous combustion to form stable combustion flames.
维普
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