“双碳”战略下,煤电是以新能源为主要电源的电网的安全保障,其中循环流化床(cir‐culatingfluidizedbed,CFB)燃烧发电技术在煤电深度调峰中担当着重要角色,但其热惯性大,制约了CFB锅炉的变负荷速率。降低粒径、改善燃料燃烧特性等燃烧调控行为可降低CFB锅炉的流动、传热和燃烧等热惯性,对提升CFB锅炉的灵活性具有重要意义。焦炭燃烧是固体燃料燃烧的主要放热过程,通过总结并对比常见的焦炭燃烧速率模型(包括动力/扩散表面反应速率模型、焦炭缩核燃烧模型和Coats-Redfern积分法),得出了焦炭燃烧的影响因素。结果表明:焦炭燃烧速率的主要影响因素为给煤粒径、床温、一二次风氧气体积分数和燃料种类;总结了上述主要影响因素对炉内燃烧速率和其他燃烧行为的影响,降低给煤粒径、升高床温、提高氧气体积分数和改善燃料特性均能改善燃料燃烧过程,提升CFB锅炉变负荷速率;基于粒径、燃料特性等因素对循环流化床炉内燃烧行为的影响,国内外研究者开发了不同技术(包括粉煤循环流化床燃烧(powderedcoalcirculatingfluidizedbedcombustion,PC-CFB燃烧)和燃料高温预热等技术)以提高CFB锅炉灵活性,亦可采用绿色低碳多元燃料掺烧等技术提高CFB锅炉的升负荷速率。

Under the “dual carbon” strategy, coal power serves as a security guarantee for  grids primarily powered by renewable energy.  Circulating fluidized bed (CFB) combustion tech‐ nology plays a crucial role in deep peak shaving for coal power, but its high thermal inertia limits the  load variation rate of CFB boilers.  Combustion control measures, such as reducing particle size and  improving fuel combustion characteristics, can effectively reduce the flow, heat transfer, and combus‐ tion inertia of CFB boilers, significantly enhancing their flexibility.  The primary heat release process  during solid fuel combustion is char combustion.  The common char combustion rate models, includ‐ ing the kinetics/diffusion surface reaction rate model, the shrinking core combustion model, and the  Coats-Redfern integration method were summarized and compared.  The results indicate that the main  factors affecting char combustion rate include coal particle size, bed temperature, volume fraction of  oxygen in primary and secondary air, and fuel type.  The effects of these factors on combustion rate  and other combustion behaviors in the furnace were summarized.  Reducing coal particle size, increas‐ ing bed temperature, raising volume fraction of oxygen, and improving fuel characteristics all con‐ tribute to improving the combustion process and enhancing the load variation rate of CFB boilers.   Based on the impacts of particle size, fuel characteristics, and other factors on combustion behavior in  CFB furnaces, researchers both domestically and internationally have developed various technologies  to improve CFB flexibility, including powdered coal circulating fluidized bed combustion and high- temperature fuel preheating.  Additionally, green low-carbon multi-fuel co-combustion technologies  can also be employed to increase the load-ramping rate of CFB boilers.