Oxy-CFB锅炉燃烧系统动态模型及其耦合特性研究

Oxy-fuel circulating fluidized bed (Oxy-CFB) combustion technology is one of the most promising main technologies in application for carbon dioxide capture in power plant. More and more researchers have paid attention to the basic problems of this technology. The recycled flue gas system and the oxygen concentration will effect on the several major balancing process in the dynamic characteristics of the Oxy-CFB boiler combustion system. Its dynamic characteristics become more complex and the research on it has not yet started.This study will build a dynamic mechanism model and an identification model for the Oxy-CFB combustion system. After an intensive study of this dynamic model, not only we will get the law of the coupling characteristics between some key parameters which will be adjusted in the Oxy-CFB combustion, but also it will show the synergy mechanisms on the combustion made by the flue gas recycle and the circulating coal. How the main operation parameters change when the combustion method switchs will also be showed. The research findings will provide scientific basis and direction for the design, the performance prediction, the automatic control and the operation adjustment in the Oxy-CFB boiler.

循环流化床富氧燃烧(Oxy-CFB)技术是目前最具应用前景的燃煤电站二氧化碳捕集技术之一，相关应用基础问题正受到国内外研究者的重视。新增的烟气再循环系统以及进口氧浓度的改变将会对主导Oxy-CFB锅炉燃烧系统动态特性的几个平衡过程产生新的影响，使其动态特性变得更加复杂，目前相关研究尚未展开。本项目拟对Oxy-CFB锅炉燃烧系统动态模型及其耦合特性进行研究，建立包含烟气再循环系统在内的Oxy-CFB锅炉的床温动态机理模型和基于混合比较建模的动态响应辨识模型，获得燃烧方式切换过程中主要运行参数的动态变化规律,阐明烟气再循环率及其组分对炉内床温、烟气含氧量的影响机制,揭示Oxy-CFB锅炉再循环烟气与其它运行调整参量对燃烧过程参数的耦合作用特性以及烟气再循环系统、物料循环等子系统对燃烧过程的协同作用机制，为Oxy-CFB锅炉的设计制造、性能预测、自动控制和运行调整提供理论依据和技术支撑。

本项目采用试验与理论相结合的研究方法对热输入功率为50kW的富氧燃烧循环流化床中试装置开展Oxy-CFB动态特性建模研究。建立了反映Oxy-CFB锅炉主要特性的简化动态数学模型；全面深入分析模型所反映的Oxy-CFB锅炉动态特性，初步获得Oxy-CFB锅炉的控制模型；得到了不同O2浓度氛围对煤的燃烧过程、化学反应、污染物生成等的影响规律；拓展了智能辨识方法和动态过程模拟平台在热工动态特性分析中的应用，获得基于智能进化算法和热工系统认识经验的辨识软件；揭示了Oxy-CFB锅炉由空气燃烧向富氧燃烧方式切换过程中床温、氧浓度等主要过程参数的动态变化规律；获得Oxy-CFB燃烧方式下，入炉煤量、O2量、再循环烟气量等输入参数的阶跃变化对床温、烟温、烟气含氧量以及烟气中CO/CO2/SO2等浓度的影响规律。相关研究成果可为后续控制系统的设计提供动态数学模型，并为逐步解决Oxy-CFB锅炉的应用基础问题提供理论依据和技术支撑，最终可为Oxy-CFB中试乃至Oxy-CFB锅炉的示范性工程以及商业设备运行进行前瞻性技术储备。