In-depth Studies of OxyCoal Combustion Processes through Numerical Modelling and 3D Flame Imaging

由于煤炭供应稳定、生产成本低，在可预见的未来，煤炭可能仍将在世界能源结构中占据重要地位。然而，要在未来碳约束的能源市场中生存，燃煤发电行业必须大幅减少污染物排放。从烟气中捕集二氧化碳的含氧煤燃烧是一项新兴技术，可适用于新的和现有的燃煤发电站，从而大幅减少碳排放。各种评估表明，氧煤技术是可行的，而且比其他CCS（碳捕集与封存）技术（如后碳捕集）更有利。目前，煤氧燃烧技术还处于实验室和技术示范阶段，对这项新技术的认识差距较大。燃烧过程中存在许多不确定性，其中传热和燃烧特性的变化是主要关注的问题。系统设计的问题，如最佳氧浓度及其影响需要进行研究。其他并发症包括高浓度的硫和汞，以及锅炉和下游元件中沉积和腐蚀的变化。如果要在发电行业广泛采用CCS技术，那么必须充分了解这些变化对燃烧过程的影响，并确定减轻所遇到问题的经济解决方案。拟议的研究旨在深入了解氧煤燃烧过程，开发过程预测的关键建模能力，并为发电行业设计新的和/或改造现有的含氧煤燃烧技术发电厂提供指导。由于进行大规模测试的高成本，过程建模通常被用作技术开发的替代方法。在本项目中，将采用先进的计算流体动力学（CFD）技术对含氧煤燃烧过程进行详细的模拟。由于氧煤燃烧与传统的空气煤燃烧有很大的不同，为了获得准确的模拟结果，将开发新的针对氧煤的CFD子程序。在CFD建模的同时，将进行控制良好的实际测量，以建立一个关于含氧煤燃烧的综合数据库，并为CFD模型的开发提供验证。此外，将开发一种独特的3D火焰监测系统来监测氧煤燃烧火焰。这种先进的计算建模、详细的实验测试和3D火焰成像的综合方法形成了一个相互验证和互补的系统，以确保可靠的研究产出，从而深入了解氧煤对燃烧过程中火焰特性、临界反应动力学以及脱挥发和焦化反应的影响。该项目财团由来自利兹、肯特和帝国理工学院的三个专业学术中心组成。中国三家领先的能源研究机构正在联合开展这项研究。双方已安排合作研究项目，在中英两国开展实验测试和理论模拟。该项目还得到了领先的发电公司和商业CFD开发商的大力支持，为氧煤燃烧测试和燃烧模型开发提供了实用的建议。该项目为英国领先的集团和中国领先的合作伙伴提供了一个平台，共同解决与氧煤燃烧技术相关的重大问题，预计该技术将为减少两国电力行业的二氧化碳和其他温室气体排放做出重大贡献。

Coal will likely remain in an important position in the world energy mix in the foreseeable future because of its stability in supply and low cost in production. However, coal fired power generation industry has to substantially reduce its pollutant emission to survive in the future carbon constrained energy market. Oxycoal combustion with CO2 capture from flue gas is an emerging technology that can be adapted to both new and existing coal-fired power stations leading to a substantial reduction in carbon emission. Various assessments suggest that oxycoal technology is feasible and more favourable than other CCS (Carbon Capture and Storage) technologies, such as post-carbon capture. Currently, oxycoal combustion technology is still in its laboratory and technology demonstration stages and there is a significant knowledge gap in this new technology. A number of uncertainties exist in the combustion process where the changes in the heat transfer and combustion characteristics are, among others, the major concerns. Issues with system designs such as the optimum oxygen concentrations and its impact need to be investigated. Other complications include such as high concentrations of sulphur and mercury and changes in deposition and corrosion in the boiler and the downstream elements. If the technology is to be widely adopted in power generation industry for CCS then it is imperative that the impacts of these changes in the combustion processes are well understood, and that economic solutions to mitigating the problems encountered are identified.The proposed research aims to achieve an in-depth understanding of the oxycoal combustion processes, to develop key modelling capabilities for process prediction, and to provide guidelines to the power generation industry on design new and/or retrofitting existing power plant with oxycoal combustion technology. Because of the high costs of performing large scale tests, process modelling is commonly used as an alternative in technology development. In this project, advanced Computational Fluid Dynamics (CFD) techniques will be employed to perform detailed simulations on the oxycoal combustion processes. Because the oxycoal combustion is very different from the conventional air-coal combustion, new oxycoal specific CFD sub-programmes will be developed in order to achieve accurate modelling results. In parallel to the CFD modelling, well controlled practical measurements will be carried out to setup a comprehensive database on the oxycoal combustion and to provide validation to the CFD model development. In addition, a unique 3D flame monitoring system will be developed to monitor the oxycoal combustion flames. This integrated approach of advanced computational modelling, detailed experimental testing, and 3D flame imaging forms a mutual validating and complementary system to ensure a credible research output so that an in-depth understanding of the impact of oxycoal on flame characteristics, critical reaction kinetics, and devolatilsation and char reaction in the combustion processes may be achieved.The project consortium comprises of three academic centres of expertise from Leeds, Kent and the Imperial College. Three leading energy research institutes in China are joint force on the research. Collaborative research programmes have been arranged to carryout experimental testing and theoretical simulation in both UK and China. The project has also gained strong supported from leading power generation companies and commercial CFD developer providing practical advice on oxycoal combustion tests and combustion model development. The project provides a platform for the leading UK groups and leading Chinese partners to work together in tackling the significant issues related to the oxycoal combustion technology, which is expected to contribute significantly in cutting the CO2 and other greenhouse gases emissions in the power industry in both countries.