循环流化床锅炉燃烧系统烟气氧含量控制

循环流化床锅炉(CFBB)具有燃煤效率高、燃料适应性广等诸多优点而广泛应用于电厂及其他工业生产过程中。通过分析循环流化床锅炉的燃烧任务与控制特点,发现锅炉燃烧系统是一个具有多参数、非线性的、时变且多变量紧密耦合的系统,其中烟气氧含量控制的好坏更是提高锅炉燃烧效率,节能环保的关键。为使锅炉运行始终保持在最佳燃烧点,可以采用带有氧量校正的串级送风调节系统或带氧量校正的送风调节系统。同时在负荷变化的过程中,为保证送风量始终略大于燃料量,采用燃料、送风的双交叉限制措施。最后,通过在某热岛中心项目所用的490t/h循环流化床锅炉上实施,验证了此烟气氧含量控制方案。

Oxygen Content Control of Flue Gas in Combustion System of Circulating Fluidized Bed Boiler

Circulating fluidized bed boiler(CFBB)has many advantages such as high coal burning efficiency and wide fuel adaptability,which is widely used in power plants and other industrial production processes.Through the analysis of the combustion task and control characteristics of CFB boiler,it is found that the boiler combustion system is a multi-parameter,nonlinear,time-varying and multi-variable tightly coupled system,in which the control of flue gas oxygen content is the key to improve the boiler combustion efficiency,energy saving and environmental protection.In order to keep the boiler operating at the optimal combustion point,cascade air supply regulating system with oxygen correction or air supply regulating system with oxygen correction can be used.At the same time,in the process of load change,in order to ensure that the air supply is always slightly greater than the amount of fuel,the use of fuel,air supply double cross limit measures.Finally,the smoke oxygen content control scheme is verified by the 490t/h circulating fluidized bed boiler used in a heat island center project.