钙基吸收剂循环吸收烟气CO2过程耦合生物质焦还原NOx机理研究

The CO2 capture process from flue gas of coal-fired power plants using calcium-based sorbents coupled with NOx reduction by biochar is proposed in this project. Calcium-based sorbents after calcination is used as a heat carrier for biomass pyrolysis. CO2/SO2 capture by calcium-based sorbent and NOx reduction by biochar from biomass pyrolysis are simultaneously achieved in carbonation process of calcium-based sorbents. And then the mutual promotion of different pollutions (such as CO2, SO2 and NOx) control processes would take place. In this project, the pyrolysis performance of biomass and the physical/chemical properties of biochar under calcined calcium-based sorbents as the heat carrier will be investigated. The mechanism of influence of calcium-based sorbent and particle flow behavior on physical/chemical properties of biochar will be discussed. The effects of chemical components, crystal structure, microstructure and CO2 capture activity of calcium-based sorbent and the particle flow behavior in gas-solid two phase flow on NOx reduction by biochar will be revealed. The coupled control approach on CO2 capture capacity of calcium-based sorbent and NOx reduction activity of biochar will be developed. The method to simultaneously improve CO2 capture capacity and NOx reduction activity will be studied and the mechanism will be revealed. The matching and optimization of the process of biomass pyrolysis and the process of CO2 capture by calcium-based sorbent/ NOx reduction by biochar will be discussed. The project research will provide a theoretical basis to develop a new technology for high-efficiency clean usage of coal energy in China.

提出钙基吸收剂循环吸收燃煤烟气CO2过程耦合生物质焦还原NOx的思路，利用煅烧钙基吸收剂作为载热体热解生物质，在钙基吸收剂碳酸化反应过程同时实现CO2/SO2吸收和生物质焦还原NOx，在各污染物协同脱除之间形成相互促进的格局，突破设置多个反应过程分别脱除污染物的局限。研究煅烧钙基吸收剂作为载热体时生物质热解和成焦特性，阐明钙基吸收剂和颗粒流动对生物质热解及其焦物理化学特性的影响机制；揭示钙基吸收剂化学组分、晶体结构、微观结构、吸收CO2活性及两相流中颗粒流动状态对生物质焦还原NOx反应的影响机理，发展钙基吸收剂循环吸收CO2与生物质焦还原NOx的耦合控制方法；提出改性方法同时提高钙基吸收剂吸收CO2性能和生物质焦还原NOx性能，并揭示机理；探讨生物质热解过程与钙基吸收剂循环吸收CO2/生物质焦还原NOx耦合过程的匹配和优化；以期为发展我国煤炭能源的高效清洁利用新技术提供理论基础。

提出钙基吸收剂循环捕集燃煤烟气CO2过程耦合生物质焦还原NOx的思路，利用煅烧钙基吸收剂作为载热体热解生物质，在钙基吸收剂碳酸化反应过程同时实现CO2/SO2吸收和生物质焦还原NOx。3年来主要开展了以下工作并获得了一系列成果：研究了钙基吸收剂作为载热体对生物质焦热解特性及同时捕集CO2和脱除NOx的影响，揭示了钙基吸收剂作为载热体制得的生物质焦脱除NO反应机理；获得了钙基吸收剂循环吸收CO2过程对生物质焦还原NOx反应特性的影响规律，探讨钙基吸收剂作用下生物质焦的化学组分、微观结构与其还原NOx反应活性之间的内在联系，发现了Cu修饰生物质能大幅度催化生物质焦还原NOx性能；揭示了经历多次捕集CO2的钙基吸收剂高温催化生物质焦还原NOx和脱除SO2的反应机理，可实现NOx和SO2超低排放；采用挤出-滚圆将钙基吸收剂与生物质混合制备球粒，研究钙基吸收剂球粒抗磨损特性、机械性能、脱碳特性及直接脱硫脱硝特性，获得了最佳造粒工艺；提出了结构可控的自组装钙基吸收剂制备方法，采用生物质模板制备微米管状、和微米球型钙基复合吸收剂，发现该类型吸收剂具有很高的CO2捕集性能和催化生物质焦脱除NOx性能；分析了Ce、Mg、Mn等多种材料对钙基吸收剂循环捕集CO2的影响规律；建立了热力学模型探讨钙基吸收剂循环捕集CO2/生物质焦还原NOx耦合过程的匹配和优化；提出基于经历多次循环捕集CO2的钙基吸收剂可用于CaO/Ca(OH)2热化学体系储热的新思路。本项目研究为基于钙循环的燃煤电站CO2、SO2和NOx协同脱除技术提供了理论指导和数据支持，有望促进高效低碳能源技术的发展。