间壁换热开采天然气水合物注入温度优化

Temperature Optimization of Natural Gas Hydrate Injection in Inter-Wall Heat Transfer Recovery

热力学法是目前公认可行的天然气水合物开采方法之一。关于如何在热采过程中提高注入能量利用率,使开采所得甲烷气体的总热值与注入热量之比最大的研究,目前大多集中于注入温度的优化方面。从获得最大产气速率的角度出发,在能量利用率的基础上,定义新的热效率为单位产气量下的水合物注热开采能量利用率。并引用无限长圆柱体换热反应釜概念,建立间壁换热开采水合物过程中等温边界条件下一维瞬态传热新模型,通过推导间壁换热过程中传热量和传热时间的解析表达式,求得在开采温度20～100℃的条件下,间壁换热开采水合物的热效率在0. 431～0. 536之间。最优注入温度为65℃,热效率为0. 536。

Thermodynamic method is currently recognized as one of the feasible exploitation methods for natural gas hydrate. How to improve the utilization ratio of injected energy in the thermal recovery process so as to maximize the ratio of the total calorific value of methane gas, the injected calorific value is mostly focused on the analysis of the optimal injection temperature. From the point of view of obtaining the maximum gas production rate, on the basis of energy utilization rate, this paper defines a new thermal efficiency as the energy utilization rate of hydrate heat injection under the unit gas production rate. Based on the concept of infinite cylindrical heat transfer reactor, a new one-dimensional transient heat transfer model under isothermal boundary conditions is established. By deriving the analytical expressions of heat transfer quantity and time in the process of inter-wall heat transfer, the thermal efficiency of inter-wall heat transfer for hydrate extraction is found to be between 0.431 and 0.536 at the mining temperature of 20~100 ℃. The optimum injection temperature is 65 ℃and the thermal efficiency is 0.536.