Numerical simulation and experimental study of the conversion of refinery gas to syngas via thermal plasma

doi:10.11949/0438-1157.20250350

Abstract

Abstract:

Thermal plasma technology shows great potential in the reforming reaction of CO₂ and hydrocarbon-rich gases due to its exceptionally high temperature, enthalpy, and electron density. In this study, numerical simulations were performed to elucidate the influence of feed ratios on the spatiotemporal evolution of species in the thermal plasma reforming system from both thermodynamics and kinetics and to predict the product composition. The simulation results indicate that the CH₄ and CO₂ reforming reaction is an ultra-fast process in thermal plasma, with complete conversion achieved within milliseconds. Owing to differences in bond dissociation energy, the dissociation of CO₂ is harder than that of CH₄, resulting in a lower formation rate of CO compared to H₂. Furthermore, as the CO₂ flow rate increases, side reactions such as CH₄ cracking are suppressed. Further experimental studies were conducted on the reforming behavior of CH₄ and refinery gas (containing CH₄, C₂H₆ and other hydrocarbons) with CO₂ in a thermal plasma reactor. The relationships were established between feed ratio, input power, and product composition. It was found that the predominant products of refinery gas reforming remained H₂ and CO. Under optimal conditions, the conversion rates of CH₄ and CO₂ reached 99.6% and 93.2%, respectively, with H₂ and CO selectivities of 83.7% and 98.3%. The above results provide a new idea for the synergistic conversion of refinery gas and CO₂ into high-value syngas.

Key words: thermal plasma, refinery gas, reforming, syngas, reaction kinetics

摘要：

热等离子体技术以其高温、高焓、高电子密度的特性，在CO₂与富烷烃气体重整领域展现出巨大潜力。本文首先通过数值模拟，从热力学和动力学两个层面揭示了原料配比对热等离子体重整体系粒子时空演化行为的影响机制并预测产物组成，表明热等离子体重整CH₄和CO₂的反应速度极快，可在毫秒尺度内完成转化；受键能影响，CO₂的解离难度大于CH₄，导致体系内CO的生成速率低于H₂的生成速率。进一步实验研究了CH₄以及复杂炼厂气（含CH₄、C₂H₆等组分）与CO₂在热等离子体反应器中的重整行为，建立了原料配比、输入功率等关键参数与产物组成的关系，发现炼厂气重整的产物仍以H₂和CO为主，最佳条件下，CH₄和CO₂的转化率分别达到99.6%和93.2%，对应H₂和CO的选择性分别为83.7%和98.3%。上述结果为炼厂气与CO₂协同转化制备高附加值合成气提供了新的思路。

关键词: 热等离子体, 炼厂气, 重整, 合成气, 反应动力学

CLC Number:

TQ 039⁺.3

Jiaqi XU, Wenjun ZHANG, Yanping YU, Baogen SU, Qilong REN, Qiwei YANG. Numerical simulation and experimental study of the conversion of refinery gas to syngas via thermal plasma[J]. CIESC Journal, 2025, 76(9): 4462-4473.

徐佳琪, 张文君, 余燕萍, 苏宝根, 任其龙, 杨启炜. 热等离子体重整炼厂气制合成气过程数值模拟与实验研究[J]. 化工学报, 2025, 76(9): 4462-4473.

Figures/Tables 14

Fig.1 Schematic diagram of the experimental process of reforming1—cathode; 2—DC power supply; 3—anode; 4—magnetic coils; 5—heat exchanger; 6—gas chromatography

Fig.2 Thermodynamic equilibrium composition of reforming reaction (CO2/CH4=1.0)

Fig.3 CH4 and CO2 equilibrium conversion rates under different feed ratios and temperatures

Fig.4 Dry reforming reaction path diagram of CH4-CO2

Fig.5 Distribution of concentration, reactor temperature and residence time in the reactor (CO2/CH4=0.43)

Fig.6 Distribution of concentration, reactor temperature and residence time in the reactor (CO2/CH4=1.0)

Fig.7 Distribution of concentration, reactor temperature and residence time in the reactor (CO2/CH4=3.00)

Fig.8 Mole fraction distribution of main components under different feed ratio

Fig.9 Comparison of simulated and experimental results of CH4 reforming with different feed ratios

Table 1 Main composition and content of refinery gas

气体	体积分数/%	气体	体积分数/%
H₂	18.93	C₃H₈	1.35
CH₄	46.49	C₃H₆	0.32
C₂H₆	15.72	C₄H₁₀	0.37
C₂H₄	0.89	N₂	14.05
CO₂	1.20

Fig.10 Rate of production analysis of C2 components

Fig.11 Reforming reaction path of C2H6

Fig.12 Refinery gas reforming at different input power: product gas composition; conversion rate of CH4 and C2H6

Fig.13 Comparison of results between refinery gas reforming and CH4 reforming under different input power

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