文档介绍：摘 要
近年来“温室效应”日益严重。CO2 是导致温室效应最主要的原因。如何减小和控制 CO2 的排放问题已经引起世界各国的高度重视。增压富氧燃烧技术作为有效控制煤燃烧 CO2 排放的技术之一,由于其具有突出的技术经济优势受到了广泛关注。然而,增压富氧燃烧研究中存在的许多问题还有待解决,增压富氧燃烧时炉内传热特性就是这样一个急需解决的问题之一。所以针对增压富氧燃烧炉内传热特性进行研究势在必行。
本文在已有研究的基础上,结合真实气体方程,考虑炉内流动、燃烧特性建立了一个增压富氧燃烧 CFB 传热模型。利用模型针对一台 440t/h CFB 锅炉, 分析各运行参数对传热的影响。发现颗粒粒径和空隙率增大,传热系数减小;温度升高,传热系数增大,由于气体发射率随温度升高而减小气体传热系数减小;压力升高,传热系数增大,压力越高,增幅越小,说明当压力升高到一定程度时,继续升高压力对传热没有太大影响。通过与其他研究者的相关实验结果进行比较检验模型的正确性。最后,根据模型对 440t/h CFB 锅炉进行初步概念性设计。在炉膛吸热量不变的情况下,压力升高,炉膛受热面减小。这就需要通过外部受热面内移或者增加外置换热床、降低返回物料量温度等来维持锅炉正常运行。该工作对增压富氧 CFB 锅炉的设计和优化运行,具有一定参考意义。
关键词:增压富氧燃烧;循环流化床;传热;模型
Abstract
Recently the “greenhouse effect” es increasingly serious and CO2 emissions are the primary source of greenhouse to reduce and control CO2 discharge problem has been paid highly attention by all the oxygen-bustion as one of the effective control of bustion CO2 emissions technology has received wide public attention because of its prominent technology and economic , many problems waiting to be solved in the study of pressurized oxygen-bustion, the heat transfer in the pressurized oxygen-enriched CFB boiler is such one urgent problem. So the research directing at the heat transfer of pressurization oxygen-enriched CFB boiler is imperative.
This paper based on the existing researches bined with real gas equations and built a model for heat transfer in a pressurized oxygen-enriched CFB boiler, which consideres flow bustion characteristics. Using the model to analyze influence of operation parameters to heat transfer. with an example of 440t/h CFB boiler. Then it found heat transfer was reducing when the particle diameter and porosity was increasing; heat transfer was increasing when the temperature was rising, gas emission rate was decreasing with temperature rising, so heat transfer was decreasing; heat transfer was increasing when pressure was rising and the higher the pressure, the greater the growth, it showed when pressure raised