Pore-scale study of coke formation and combustion in porous media using lattice Boltzmann method
Pore-scale study of coke formation and combustion in porous media using lattice Boltzmann method
复制标题
使用格子玻尔兹曼方法研究多孔介质中焦炭的形成和燃烧
DOI：
10.1016/j.proci.2022.09.053
复制
发表时间：
2023
影响因子：
3.4
通讯作者：
Lei T
中科院分区：
文献类型：
--
作者：
Lei T
火烧油层技术是一种很有前途的稠油开采技术。然而，ISC包括多个物理化学过程，这仍然是知之甚少，难以预测和控制。本研究建立了一个格子Boltzmann（LB）模型，在孔隙尺度上模拟ISC的两个重要方面：焦炭的形成和燃烧。LB模型包括热膨胀效应，并解决了反应性空气焦炭界面没有迭代。此外，该模型通过考虑焦炭形成和两步焦炭燃烧以及固体几何形状的增长，改进了以前的模型。结果表明，LB模型正确地捕捉焦炭燃烧特性。同时，新引入的焦炭形成和两步燃烧产生重要的发现。随着燃烧释放的热量向下游转移，成功地跟踪了燃烧前沿之前的油裂解和焦炭形成。产生的焦炭为上游燃烧提供燃料，使系统自我维持。在焦炭的形成和燃烧过程中，四个焦炭过渡态被确定。此外，参数研究表明，大的入口氧含量和驱动力是可取的，但应避免太高的驱动力，因为它会导致高的燃烧温度。此外，建议应适当设置进气温度。一方面，高温可能促进焦炭的形成并阻碍锋面扩展。另一方面，即使温度足够高以确保焦炭1的点燃，低温也可能减慢焦炭2的燃烧。焦炭2燃烧减速可能进一步导致热量释放不足和焦炭形成失败，从而导致燃烧提前终止。入口温度的这种影响表明考虑焦炭形成和两步焦炭燃烧的必要性。这些结果有助于提高对ISC的认识，促进ISC的发展。
In-situ combustion (ISC) has long been recognized as a promising technique for heavy oil recovery. However, ISC includes multiple physicochemical processes, which are still poorly understood and difficult to predict and control. This study establishes a lattice Boltzmann (LB) model to simulate the two important aspects of ISC at the pore scale: coke formation and combustion. The LB model includes thermal expansion effects and solves the reactive air-coke interface without iterations. Moreover, this model improves upon previous models by considering both coke formation and two-step coke combustion, as well as the growth of solid geometry. Results show that the LB model correctly captures coke combustion properties. Meanwhile, the newly introduced coke formation and two-step combustion yield important findings. As heat released from combustion transfers downstream, oil cracking and coke formation ahead of the combustion front are successfully tracked. The generated coke fuels the upstream combustion, making the system self-sustained. During coke formation and combustion, four coke transition states are identified. In addition, a parametric study demonstrates that the large inlet oxygen content and driving force are desirable, while too high a driving force should be avoided as it causes high burning temperature. Furthermore, it suggests that the inlet air temperature should be set appropriately. On one hand, a high temperature may promote coke formation and retard the front propagation. On the other hand, a low temperature may slow down the combustion of coke 2, even though it is high enough to ensure the ignition of coke 1. The decelerated coke 2 combustion may further cause the insufficient heat release and the failed coke formation, thus inducing the early termination of combustion. Such effects of the inlet temperature indicate the necessity of considering coke formation and two-step coke combustion. These results help to improve the understanding and facilitate the development of ISC.