天然气气化炉内介质乙二醇非稳态耦合热流场研究

目的 在天然气工业化应用中,液化天然气的高效气化是关键影响因素,为了在国家能源改革的大背景下,尽可能提升现有气化设备的运行效能,采用 ANSYS Fluent 软件对一种采用乙二醇作为中间载热介质的天然气气化炉内非稳态耦合热流场进行数值模拟。 方法 通过深入研究天然气气化炉传热传质机理,在总结前人研究仅考虑对流换热情况不足的情况下,将辐射换热加以考虑,构建出大空间非稳态自然对流及介质参与性辐射耦合传热模型,通过天然气加热、传热流动试验装置,对边界条件进行实验校准,验证数值分析模型的正确性。 结果 中间载热介质为乙二醇的气化炉运行时长达到 2. 0 h 后,传热量趋于稳定,内部热流场不再发生明显扰动,表明气化炉进入稳定运行阶段,此时炉内整体加热效率仅为 87. 35%,其中介质参与性辐射占总传热量的 27. 01%,气化炉底部形了范围较小的低温带,表明该工况下其内部运行存在难以消除的流动死角。 结论 在本文设置的工况下成,大筒体天然气气化炉内部流场分布情况不佳,气化炉的加热效率和启动时间有待进一步优化,炉内主要换热形式仍是自然对流,但不可忽略介质参与性辐射对总传热的贡献。

Unsteady Coupled Heat Flow Field of Medium Ethylene Glycol in Natural Gas Gasifier

Objective The efficient gasification of liquefied natural gas LNG is a key influencing factor in the industrialapplication of natural gas. In order to improve the operation efficiency of the existing gasification equipment in the contextof national energy reform ANSYS Fluent software was used to numerically simulate the unsteady coupled heat flow field ina natural gas gasifier using ethylene glycol as the intermediate heat-carrying medium. Methods The heat and masstransfer mechanism of natural gas gasifiers was studied in depth. It was found that previous studies only consideredconvective heat transfer. Considering the radiative heat transfer a coupled heat transfer model of unsteady naturalconvection and medium participating radiation in a large space was constructed. The boundary conditions were verified andcalibrated by natural gas heating and heat transfer flow experimental equipment. The correctness of the numerical analysismodel was verified. Results When the running time of the gasifier with ethylene glycol as the intermediate heat-carryingmedium reached 2. 0 h the heat transfer tended to be stable. As the internal thermal flow field was no longer obviouslydisturbed the gasifier entered a stable operation stage. At this time the overall heating efficiency in the furnace was only87. 35% in which the medium participating radiation accounted for 27. 01% of the total heat transfer. In addition asmall range of low-temperature zones was formed at the bottom of the gasifier indicating that there was a flow dead angle that was difficult to eliminate in its internal operation under this working condition. Conclusion Under the working conditions set in this paper the internal flow field distribution of the large cylinder natural gas gasifier is not good and theheating efficiency and start-up time of the gasifier need to be further optimized. The main form of heat transfer in thefurnace is still natural convection but the contribution of medium participating radiation to the total heat transfer cannot beignored.