循环流化床实时动态数学模型研究

A Real Time Dynamic Mathemtical Model of CFBC.

与常规煤粉燃烧相比，循环流化床的特点在于：首先，床内存在大量并不断循环的物料，其质量、粒度分布、循环程度、浓度分布、热容量等对动态特性有重大影响；其次，床料内存在着大量的未燃尽残碳，其动态燃烧及消耗过程以及燃烧放热位置对炉温及其分布影响很大。针对上述特点，建立了以给煤量、给风量、排渣量为输入的动态数学模型，它由氧质量平衡、残碳动态燃烧过程的碳质量平衡、挥发份燃烧及残碳燃烧的动态能量平衡以及以排渣量为主动操作量的动态床料质量平衡４个方程组成。计算结果表明：该模型能够正确地反映各种操作量变化时循环流化床的动态特性，而且计算速度满足实时要求。

Abstract Compared to conventional purverized coal combustion, CFBC has some distinguished feature. In CFBC, the bed inventory is very large, its mass, size distribution, circulating rate, concentration distribution and heat capacity have great influence on dynamic behavior. Furthermore, there is large amount of unburned carbon in bed inventory, which kinetic combustion and consumption process and location have great influence on the temperature level and distribution in combustion chamber. Considering above features, this paper established a dynamic model by taking the rates of coal feed, air feed and bottom ash removal as inputs. The model mainly consists of four balance equations. They are separately the mass balance of oxygen, dynamic carbon mass balance considering the kinetic reactions of all unburned carbon, dynamic mass balance of total bed inventory by taking ash removal as operator mainipulating variable and a total energy balance with consideration of the combustion of volatile and unburned carbon. A series of model tests are made for different operation conditions. The calculation results show that the model can correctly reflect the dynamic processes when changing the above mentioned operation inputs and the computing speed meets the requirement of real time simulation. Fig 1 and refs 2.