水气转化对超临界水煤气化的抑制特性

doi:10.11949/0438-1157.20240231

摘要/Abstract

摘要：

水气转化是煤炭超临界水气化技术中关键的均相化学反应。然而，水气转化反应对煤颗粒孔隙内非均相气化反应的影响尚不清楚。通过三维数值模拟，研究了颗粒孔隙内部水气转化反应对不规则煤颗粒超临界水气化过程的作用机理。研究结果表明，孔隙内的水气转化反应掉了大量用于煤的非均相气化反应的超临界水，降低了颗粒的气化反应速率，同时大量生成二氧化碳并富集于颗粒孔隙中，减小了孔隙中超临界水的扩散系数。定义了有效气化因子以定量表征水气转化反应对颗粒气化的抑制程度，发现了该抑制作用随颗粒粒径的增大而增强，且由于该抑制作用而增加的颗粒气化反应时间与有效气化因子呈简单对数关系。

关键词: 多孔颗粒, 多相反应, 煤炭, 超临界水气化

Abstract:

Water-gas shift reaction (WGSR) is a key homogeneous reaction in the supercritical water gasification (SCWG) of coal, but the impact of the WGSR on the heterogeneous reaction of coal in the particle pores remains unclear. The mechanism of intrapore water-gas shift reaction on the SCWG of irregular-shaped coal particles was investigated through three-dimensional numerical simulation. It is revealed that the intrapore WGSR consumed a significant amount of supercritical water intended for the heterogeneous reaction of coal, inhibiting the gasification rate. Additionally, a large amount of CO₂ was generated and accumulated in the particle pores, reducing the diffusion coefficient of the supercritical water. An effective gasification factor was introduced to quantitatively characterize the inhibition by the intrapore WGSR, showing that the inhibition effect increased with the particle size. The increased gasification time of the coal particle due to the inhibition was found to have a simple logarithmic relationship with the effective gasification factor.

Key words: porous particles, heterogeneous reaction, coal, supercritical water gasification

中图分类号:

TQ 541

赵帅琪, 张瑞, 黄瀚, 赵昆鹏, 白博峰. 水气转化对超临界水煤气化的抑制特性[J]. 化工学报, 2024, 75(8): 2960-2969.

Shuaiqi ZHAO, Rui ZHANG, Han HUANG, Kunpeng ZHAO, Bofeng BAI. Inhibition of water-gas shift reaction on coal gasification in supercritical water[J]. CIESC Journal, 2024, 75(8): 2960-2969.

图/表 6

表1 数值模拟算例设置

Table 1 Simulation case set-up

算例	颗粒当量直径/mm	水气转化反应	算例	颗粒当量直径/mm	水气转化反应
Case1	0.2	考虑	Case10	0.2	忽略
Case2	0.4	考虑	Case11	0.4	忽略
Case3	0.6	考虑	Case12	0.6	忽略
Case4	0.8	考虑	Case13	0.8	忽略
Case5	1.0	考虑	Case14	1.0	忽略
Case6	1.4	考虑	Case15	1.4	忽略
Case7	1.8	考虑	Case16	1.8	忽略
Case8	2.0	考虑	Case17	2.0	忽略
Case9	2.4	考虑	Case18	2.4	忽略

图1 超临界水气化过程中煤颗粒内部非均相反应锋面形貌、流体组分分布、温度分布和孔隙率分布随颗粒转化率的演化

Fig.1 Evolution of heterogeneous reaction front morphology, fluid species distributions, temperature distribution and porosity distribution inside the coal particle during the SCWG

图2 分别考虑与忽略颗粒孔隙内部水气转化反应时，气化反应的对比和组分扩散的对比

Fig.2 Comparison of heterogeneous reaction as well as comparison of species diffusion in the SCWG with or without the intrapore WGSR

图3 超临界水气化过程中不同粒径颗粒的传热速率、传质速率、气化反应速率和有效因子随颗粒转化率的变化

Fig.3 Variation of heat transport rate, species diffusion rate, heterogeneous reaction rate and effectiveness factor with particle conversion of particles with different sizes

图4 分别考虑与忽略颗粒孔隙内部水气转化反应时，不同粒径颗粒到达85%转化率时的气化时间（tc1—考虑, tc2—忽略），不同粒径颗粒的有效气化因子

Fig.4 Gasification time (when particle conversion X = 85%) of particles with different sizes in the SCWG with or without intrapore WGSR (tc1—with, tc2—without), effective gasification factor of particles with different sizes

图5 分别考虑与忽略颗粒孔隙内部水气转化反应时，颗粒转化率到达85%时的气化时间之比随颗粒有效气化因子的变化（tc1—考虑, tc2—忽略）

Fig.5 Ratio of gasification time (when particle conversion X = 85%) of the SCWG with and without intrapore WGSR versus effective gasification factor of particles (tc1—with, tc2—without)

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