CFD modeling investigation of oxy-fuel combustion application in an industrial-scale FCC regenerator

IF 5.6 2区 工程技术 Q2 ENERGY & FUELS Journal of The Energy Institute Pub Date : 2024-08-16 DOI:10.1016/j.joei.2024.101796
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Abstract

The increase in atmospheric CO2 concentration and its consequential impact on climate change have elicited increased public concern. The refinery units including fluid catalytic cracking (FCC) generate substantial quantities of CO2. To mitigate the emission from the FCC process, oxy-fuel combustion has emerged as a prospective carbon capture and storage technology. This study presents the first trial for the modeling investigation of a 70 kt/a industrial FCC regenerator under the scenario of retrofitting it with oxy-fuel combustion technology. Employing the Eulerian-Eulerian model, a CFD model integrating heat transfer and coke combustion reactions has been established. The detailed hydrodynamics, temperature, and species concentration distribution inside the regenerator are obtained under both air-firing and oxy-firing conditions, which are further compared to exploit the possibility of oxy-fuel combustion retrofitting. As has been found, decreases in gas temperature and carbon conversion rate were observed for 21 % O2/79 % CO2 atmosphere in comparison to the air reference case due to the differences in gas properties between N2 and CO2. This discrepancy resulted in a drop of 17 K in dilute phase temperature and 2 K in dense phase temperature. The bed density also exhibited a large with the oxy-firing conditions, with notable observations revealing a lower bed density below a height of 4.2 m, transitioning to a higher density above said height. Sensitivity analysis was also conducted for three principal operating parameters, including superficial gas velocity, oxygen partial pressure, and catalyst circulation rate. An increase of oxygen partial pressure to 27 % or a decrease of the catalyst circulation rate to 20.7 kg/s proved effective in achieving the same temperature profile and even a slightly better carbon conversion in comparison to air-firing regeneration.

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全氧燃烧在工业规模催化裂化再生器中应用的 CFD 建模研究
大气中二氧化碳浓度的增加及其对气候变化的影响引起了公众越来越多的关注。包括流体催化裂化(FCC)在内的炼油装置会产生大量的二氧化碳。为减少催化裂化过程中的二氧化碳排放,富氧燃烧技术已成为一种前景广阔的碳捕集与封存技术。本研究首次尝试了在 70 kt/a 工业催化裂化再生装置改造为全氧燃烧技术的情况下,对该装置进行建模研究。采用欧拉-欧拉模型,建立了一个集成传热和焦炭燃烧反应的 CFD 模型。在空气燃烧和全氧燃烧条件下,获得了再生器内部详细的流体力学、温度和物种浓度分布,并对其进行了进一步比较,以探讨全氧燃烧改造的可能性。研究发现,由于 N2 和 CO2 的气体特性不同,在 21%O2/79%CO2 的气氛中,气体温度和碳转化率与空气参考情况相比都有所下降。这种差异导致稀相温度下降 17 K,浓相温度下降 2 K。床层密度也随着全氧燃烧条件的变化而变化,值得注意的是,在 4.2 米高度以下的床层密度较低,而在该高度以上的床层密度较高。还对三个主要操作参数进行了敏感性分析,包括表层气体速度、氧分压和催化剂循环速率。事实证明,将氧分压提高到 27% 或将催化剂循环速率降低到 20.7 kg/s,可有效实现相同的温度曲线,与空气燃烧再生相比,碳转化率甚至略有提高。
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来源期刊
Journal of The Energy Institute
Journal of The Energy Institute 工程技术-能源与燃料
CiteScore
10.60
自引率
5.30%
发文量
166
审稿时长
16 days
期刊介绍: The Journal of the Energy Institute provides peer reviewed coverage of original high quality research on energy, engineering and technology.The coverage is broad and the main areas of interest include: Combustion engineering and associated technologies; process heating; power generation; engines and propulsion; emissions and environmental pollution control; clean coal technologies; carbon abatement technologies Emissions and environmental pollution control; safety and hazards; Clean coal technologies; carbon abatement technologies, including carbon capture and storage, CCS; Petroleum engineering and fuel quality, including storage and transport Alternative energy sources; biomass utilisation and biomass conversion technologies; energy from waste, incineration and recycling Energy conversion, energy recovery and energy efficiency; space heating, fuel cells, heat pumps and cooling systems Energy storage The journal''s coverage reflects changes in energy technology that result from the transition to more efficient energy production and end use together with reduced carbon emission.
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