循环流化床中颗粒内循环与循环流化床锅炉的设计

本文从循环床锅炉密相区的热平衡计算出发，探讨了密相区内受热面面积及密相区高度与飞灰循环倍率、密相区燃烧份额的关系，并以４种典型煤种为例，分析了煤种变化对密相区高度的影响。设计计算和运行经验相结合，在密相区热平衡分析中，引入了床内粒子循环的概念，从而对密相区内热平衡和受热面面积的确定有更深入的理解。

In Bed Recirculation of Particle and Design of Circulating Fluidized Bed Boiler

The circulating fluidized bed combustion technology was extensively developed in recent years in China.The size of coal fed ranges from 0 mm to 10 mm and the mean diameter of coal ranges from 2 mm to 3.5 mm leading to that the fluidized bed consists of a dense phse zone and dilute phase zone.This means that the coal combustion fraction in the dense phase zone is larger,so the heat balance and heat exchange surface area of the dense phase zone are very important.If the heat exchange area is designed too much or not enough,the circulating fluidized bed bolier can not run stably.This paper analyses the heat balance and conducts the design of heat exchange surface of the dense phase zone for a circulating fluidized bed boiler of 75 t/h steam capacity.The effect of coal type,recirculation ratio of fly ash and coal combustion fraction on amount of heat exchange surface and height of dense phase zone are also described.