石油焦和煤化学链燃烧发电系统能耗、效率和温室气体排放研究

Energy consumption, efficiency, and greenhouse gas emissions study of petroleum coke and coal chemical looping combustion for power generation systems

  • 摘要: 劣质石油焦由于其碳含量高和热值高常被用作燃料,但其在燃烧过程中会排放大量CO2。将石油焦用于化学链燃烧发电是实现其清洁利用的有效途径,但该过程仍面临石油焦转化率低的问题。将石油焦与煤混合作为燃料可显著提高石油焦的燃烧反应活性。因此,建立了石油焦−煤以质量比1∶1为燃料和煤单独为燃料的化学链燃烧发电系统,对燃料反应器中分解燃料充分反应所需载氧体循环量和空气反应器中再生载氧体所需空气流量进行优化,并从系统效率、生命周期化石能源消耗和温室气体排放方面将其与石油焦单独化学链燃烧发电系统的性能进行分析比较。结果表明,石油焦−煤化学链燃烧发电系统和煤化学链燃烧发电系统中所需循环载氧体和燃料的质量比为26.43和24.19,再生载氧体所需空气与燃料的质量比为9.22和8.43。石油焦−煤化学链燃烧电厂的效率为36.77%,分别比石油焦和煤单独为燃料的电厂高8.96%和2.20%。石油焦−煤混合为燃料电厂的生命周期化石能源消耗和温室气体排放为9.52 GJ/MWh和302.76 kg CO2 eq/MWh,分别比石油焦和煤单独为燃料电厂低2.56和0.27 GJ/MWh、35.27和4.03 kg CO2 eq/MWh。将石油焦与煤混合作为燃料提高石油焦的燃烧转化率后可显著提高发电系统的能量效率,同时降低发电过程的生命周期化石能源消耗和温室气体排放。

     

    Abstract: Poor-quality petroleum coke is often used as fuel because of its high carbon content and calorific value, but its combustion process will emit a lot of CO2. Using the petroleum coke chemical looping combustion (CLC) for power generation is an effective way to realize its clean utilization, but the process still faces the problem of low conversion rate of petroleum coke. Mixing petroleum coke with coal as fuel can significantly improve the reactivity of petroleum coke. Therefore, this study established a CLC power generation system with a mixture fuel of petroleum coke and coal at a mass ratio of 1:1 and coal as the only fuel. The amount of oxygen carrier circulation required for a full reaction of decomposed fuel in the fuel reactor and the air flow required for the regeneration of oxygen carrier in the air reactor were optimized. The novel system was compared with a petroleum coke CLC power generation system in terms of system efficiency, life cycle fossil energy consumption and greenhouse gas emissions. The results show that the optimum mass ratios of circulating oxygen carrier to fuel required in the petroleum coke-coal and coal CLC power generation systems are 26.43 and 24.19, while their optimum mass ratios of air to fuel required for regenerating oxygen carrier are 9.22 and 8.43. The energy efficiencies of the new CLC power plant are 36.77%, which are 8.96 and 2.20 percentage points higher than that of the CLC power plant using petroleum coke and coal as fuel alone. The life cycle fossil energy consumption and the greenhouse gas emissions of the petroleum-coal hybrid CLC power plant are 9.52 GJ/MWh and 302.76 kg CO2 eq/MWh, which are 2.56 and 0.27 GJ/MWh, 35.27 and 4.03 kg CO2 eq/MWh lower than that of petroleum coke and coal power plants alone. The energy efficiency of the power generation system can be significantly increased by mixing petroleum coke with coal to improve the combustion conversion rate of petroleum coke, while the life cycle fossil energy consumption and greenhouse gas emissions of the power generation system can be reduced.

     

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