谭厚章,王学斌,杨富鑫,等. 大型燃煤发电机组低碳技术进展[J]. 煤炭学报,2024,49(2):1052−1066. DOI: 10.13225/j.cnki.jccs.ZZ24.0060
引用本文: 谭厚章,王学斌,杨富鑫,等. 大型燃煤发电机组低碳技术进展[J]. 煤炭学报,2024,49(2):1052−1066. DOI: 10.13225/j.cnki.jccs.ZZ24.0060
TAN Houzhang,WANG Xuebin,YANG Fuxin,et al. Progress in low carbon technologies for large-scale coal-fired power plants[J]. Journal of China Coal Society,2024,49(2):1052−1066. DOI: 10.13225/j.cnki.jccs.ZZ24.0060
Citation: TAN Houzhang,WANG Xuebin,YANG Fuxin,et al. Progress in low carbon technologies for large-scale coal-fired power plants[J]. Journal of China Coal Society,2024,49(2):1052−1066. DOI: 10.13225/j.cnki.jccs.ZZ24.0060

大型燃煤发电机组低碳技术进展

Progress in low carbon technologies for large-scale coal-fired power plants

  • 摘要: 当前我国碳排放总量约110亿t,其中约40%的CO2由燃煤机组产生,如何降低燃煤发电机组的碳排放是实现双碳目标的关键。针对燃煤发电机组大规模减碳技术,重点介绍低碳/零碳燃料替代技术(生物质、污泥、氢/氨等)和CCUS技术的研究进展:燃煤电厂耦合生物质包括直接耦合和间接耦合,但均受制于生物质原料供应和价格,生物质“种植—收割—转运—储存—预处理—燃烧”全链条控制掺烧模式可有效解决上述问题。660 MW机组掺烧试验表明,CO2排放可减少77.25万t/a;市政污泥含水率高达80%,进入锅炉前需干化处理,目前蒸汽或烟气干化均存在投资运行成本高、干化后的污泥水分较大且有臭气等问题,导致掺烧比例一般低于8%。基于生物质热源的污泥炭化技术可直接在污水厂生产无臭污泥炭,热值达10.26 MJ/kg左右,电厂掺烧比例可提高至20%~30%;掺烧氢/氨燃料需解决大比例掺烧下氨逃逸和NOx排放问题,国内已开展皖能集团300 MW和国家能源集团600 MW氨煤掺烧实验,通过燃烧调控可在NOx排放略微增加的情况下实现较高的NH3燃烬率,但商业化推广还受制于氢/氨成本;燃烧前脱碳技术(IGCC电站)的商业化运行案例极为有限,由于高居不下的成本,国外多个示范项目均已停运,推动该技术商业化需解决建设成本、发电成本和设备可靠性等问题。燃烧中碳捕集包括富氧燃烧和化学链燃烧,由于空分、再循环等过程能耗,常压富氧发电效率比空气燃烧低8%~12%,从常压富氧到加压富氧可进一步提高净发电效率;我国已建成全球最大的4 MW化学链燃烧示范装置,该技术也有望应用于气化领域;燃烧后碳捕集目前以溶液吸收技术为主,固体吸附技术的再生能耗更低,但大规模商业化需要继续降低能耗和成本。

     

    Abstract: China’s total carbon emissions are approximately 11 billion tons, with around 40% of CO2 being produced by the coal-fired power plants (CFPP). Therefore, reducing carbon emissions from the CFPP is critical in achieving the Dual-Carbon target. This paper focused on the advancements in the low-carbon/carbon-neutral fuel substitution technologies (such as biomass, sludge, hydrogen/ammonia, etc.) and the CCUS (carbon capture, utilization and storage). The CFPP coupled with biomass includes direct and indirect coupling, but are subject to the supply and price of biomass feedstock. To address these challenges, a comprehensive “planting-harvesting-transportation-storage-pretreatment-combustion” approach was recommended to ensure an effective control throughout the entire chain. Initial pilot test on a 660 MW CFPP revealed a substantial reduction in CO2 emissions by 772500 tons annually. The high-water content of municipal sludge, reaching up to 80%, necessitates drying prior to entering the boiler. Current steam drying and flue gas drying technologies entail substantial investment and operational costs, with the dried sludge still retaining high water content and associated problems such as odor. Consequently, the blending ratio in the CFPP remains below 8%. A sludge carbonization technology based on a biomass heat source can address these challenges, which allows for the direct production of odorless sludge char in sewage plants with a calorific value of about 10.26 MJ/kg. This technology enables an increased blending ratio in the CFPP to 20%−30%, thereby significantly reducing coal consumption and CO2 emissions. The blending of hydrogen/ammonia necessitates addressing the issues of ammonia escape and NOx emission under high blending ratios. Experiments for co-firing of coal and ammonia were conducted on 300 MW and 600 MW CFPP in China to address the challenges of ammonia escape and NOx emissions under high blending ratios. The results showed that combustion control can achieve a higher NH3 burn-up rate with a slight increase in NOx emissions. However, the commercialization of hydrogen/ammonia blending in the CFPP is constrained by the cost of hydrogen and ammonia. The commercialization of pre-combustion decarbonization technology, such as IGCC, faces significant limitations due to high costs. Several foreign demonstration projects were discontinued. The construction costs and equipment reliability are crucial for promoting the commercialization of this technology. Carbon capture technologies in combustion processes include oxygen-enriched combustion and chemical chain combustion. The power generation efficiency of atmospheric oxyfuel combustion is lower by 8%−12% compared to air combustion due to the energy consumption associated with air separation and recycling processes. Transitioning from atmospheric oxyfuel combustion to pressurized oxyfuel combustion can further increase the net power generation efficiency. Notably, China has constructed the world’s largest 4 MW chemical-looping combustion (LCL) demonstration plant. The LCL also has a potential application in the gasification industry. Post-combustion carbon capture predominantly employs the solution absorption technology, while the solid adsorption technology offers a lower regeneration energy consumption. However, some challenges remain in reducing energy consumption and costs to facilitate the large-scale commercialization of this technology.

     

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