Accelerating gas production of the depressurization-induced natural gas hydrate by electrical heating
Accelerating gas production of the depressurization-induced natural gas hydrate by electrical heating
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电加热加速天然气水合物减压产气
DOI：
10.1016/j.petrol.2021.109735
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发表时间：
2021-10-30
影响因子：
--
通讯作者：
Sun, Baojiang
中科院分区：
文献类型：
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作者：
Liu, Shuyang;Li, Hangyu;Sun, Baojiang
天然气水合物(NGH)具有清洁能源和储量大的特点，将成为未来的主要能源之一。降压是从水合物中提取天然气的一种有效方法，但在单次降压过程中，由于供热不足，水合物分解产气可能会受到结冰和水合物重整的干扰。为解决这一问题，本工作对电加热降压甲烷水合物产气进行了模拟研究。采用连续加热和间歇加热两种方式，优化了电加热方案，实现了高能效、高产气率的综合效果。结果表明，电加热有利于快速分解水合物产气。在连续加热中，高初始水化饱和度、低初始含水饱和度、低比热容和高导热系数导致高产气率和高效电能利用(高能效比)。间歇加热比连续加热具有更高的电能利用效率。采用AdaGrad软件的梯度下降法确定最佳方案为前半段加热方式，最佳电加热功率为25.6W，加热时间为12.5min。与基线连续供热方案相比，优化方案的能效比(10.70)提高了24.7%，平均产气率(2.55SML/S)提高了18.2%。希望这项工作的发现能为从天然气水合物矿床中提取天然气提供一些见解。
Natural gas hydrate (NGH) will be one of the major future energy sources due to its properties of clean energy and large reserves. Depressurization is proposed as an effective method to extract natural gas from hydrate, however, the gas production from hydrate dissociation may be interrupted by ice generation and hydrate reformation due to insufficient heat supply in the single depressurization process. To solve this issue, this work conducted simulation on accelerating gas production from the depressurization-induced methane hydrate by electrical heating. The continuous heating and intermittent heating modes were employed and then the electrical heating scheme was optimized for the comprehensive effect of high energy efficiency and high gas production rate. The results show that electrical heating is conducive to gas production from hydrate dissociation at a rapid rate. In the continuous heating, a high initial hydration saturation, low initial water saturation, low specific heat capacity, and high thermal conductivity result in the high gas generation rate and efficient electrical energy utilization (a large energy efficiency ratio). The intermittent heating has a higher efficient utilization of electrical energy than continuous heating. The optimal scheme is determined as the first-half heating type with the optimized electrical heating power of 25.6 W and the heating time of 12.5 min by the gradient descent method of AdaGrad. Compared to the baseline continuous heating case, the energy efficiency ratio (10.70) of the optimal scheme is enhanced by 24.7% with the average gas production rate (2.55 SmL/s) enhanced by 18.2%. It's hoped that the findings of this work can provide some insights into extracting natural gas from gas hydrate deposits.