Oxyfuel Combustion - Academic Programme for the UK

如果煤燃烧发电时产生的二氧化碳能被集中收集起来，那么它就能被压缩成致密的液体，并被挤压到地下一公里或更深的岩石颗粒之间的孔隙中。通过将二氧化碳（CO2）放入多孔岩石被一层非多孔岩石密封的地方，我们可以非常确信，大部分二氧化碳将在那里停留数万年，因此它不会增加危险的气候变化的风险。但目前的燃煤电厂并没有以浓缩的形式释放二氧化碳；它与燃烧煤炭的空气中大约五倍体积的氮和氧混合在一起。避免这种情况的一种方法是在纯氧中而不是在空气中燃烧煤。我们知道这在理论上是可行的，但是如果纯氧——或者实际上是一种由氧气和循环燃烧产物组成的“合成空气”，而不是氮气——被用来燃烧煤炭，那么许多事情将与使用空气不同。这个项目将发展对电厂建设者和运营者需要预测和应对这些差异的科学理解。为了更好地科学理解含氧燃料燃烧，我们将在一个150千瓦的实验室燃烧器上进行实验。与真正的发电厂燃烧器相比，这是很小的（尺寸的1% !），但它将使用相同的氧气/烟气混合物。将开发计算机模型来分析煤在实验室规模燃烧器中的燃烧情况。这些模型可以应用于全尺寸燃烧器。利用现代计算机系统提供的能量，现在有可能跟踪火焰中所有旋转气体和粒子的行为，并观察它们在非常短的时间间隔内的运动和反应。这是可能的，但我们仍在学习如何正确地做到这一点。为了帮助我们做到这一点，我们正在对实验室的氧燃料火焰进行高速（每秒1000帧）视频记录，以了解它们如何真正流动和闪烁，并使用激光发出的明亮而精确的光束来帮助跟踪粒子如何移动，并告诉我们存在哪种气体混合物。我们也在特殊的测试设备中重现火焰中发生的一些事情，这样我们就有了更简单的东西来测量。然后将这些测量结果输入计算机模型。煤颗粒首先如何着火，然后如何烧焦和燃烧尤为重要。我们也对煤中的灰分如何表现感兴趣。它可能会导致空气火力发电厂的墙壁涂层出现问题，但经过大量的经验，我们知道如何避免这种情况。其中一些经验教训可能要重新学习氧燃料燃烧和专家谁帮助整理空气燃烧现在开始做我们的项目。我们还在研究含氧燃料燃烧产物如何影响锅炉中使用的钢材；可能需要新的材料，特别是在炎热或尘土飞扬的地区。最后，我们需要训练有素的科学家和工程师来帮助设计和建造这些新型发电厂。我们的项目将帮助培训其中的一些人，并在学术界积累经验，以便在工业界建造和运营新的含氧燃料工厂时提供建议。我们还将开发一些新的测量技术，可用于帮助调整第一批工厂，以提供最佳性能。但是没有一个项目可以做到这一切。因此，我们正在与英国和海外的其他组织密切合作——国际能源署温室气体计划协调了一个我们也属于的优秀网络。随着我们了解的越来越多，我们也希望能提出更多需要回答的问题，以及一些解决问题的好主意。

If the carbon dioxide produced when coal is burnt to make electricity can be collected in a concentrated form then it can be compressed into a dense liquid and squeezed into the pores between rock grains a kilometre or more underground. By putting the carbon dioxide (CO2 ) in places where the porous rocks are sealed by layer of non-porous rocks we can be very confident that most of it will stay there for tens of thousands of years, so it won't increase the risk of dangerous climate change. But current coal power stations don't release the CO2 in a concentrated form; it is mixed with about five times its volume of nitrogen and oxygen, from the air used to burn the coal. One way to avoid this is to burn the coal in pure oxygen instead of air. We know this can theoretically be made to work, but if pure oxygen - or really a 'synthetic air' made up of oxygen and recycled combustion products instead of nitrogen - is used to burn coal then many things would be different from using air. This project will develop the scientific understanding that power plant builders and operators need to predict and cope with these differences.To help develop a better scientific understanding of oxyfuel combustion we will undertake experiments in a 150 kW laboratory burner. This is small (1% of the size!) compared to real power plant burners, but it will use the same oxygen/flue gas mixture. Computer models will be developed to analyse how the coal burns in the laboratory scale burner. These models can then be applied to full scale burners. Using the power available from modern computer systems it is now possible to track the behaviour of all of the swirling gases and particles in a flame ands see how they move and react over very small intervals of time. It's possible - but we are still learning how to do it properly. To help us do this we are taking high speed (1000 frames per second) video recordings of our laboratory oxyfuel flames to see how they really flow and flicker and using the bright and precise beams from laser to help track how particles move and to tell us what sort of gas mixtures are present.We are also reproducing just some of the things that happen in flame in special test equipment so that we have simpler things to measure. These measurements then go into the computer models. How coal particles first catch alight and then how they char and burn are particularly important. We are also interested how the ash in the coal will behave. It can cause problems coating the walls of air-fired power plants, but after a lot of experience we know how to avoid that. Some of those lessons are probably going to have to be re-learned for oxyfuel combustion and the experts who help to sort out air combustion are now starting to do that on our project. We are also looking at how oxyfuel combustion products might attack the steels used in boilers; new materials might be needed, especially in hot or dusty locations.Finally, we need to have trained scientists and engineers to help design and build these new types of power plants. Our project will help to train a number of these, and also build up the experience in the academic community that can be used to advise industry when they come to build and operate new oxyfuel plants. We will also have developed some of the new measurement techniques that can be used to help tune the first plants to give the best possible performance.But no project can do it all. So we are working closely with other groups in the UK and overseas - the IEA Greenhouse Gas Programme coordinates an excellent network that we belong too. And as we learn more we also expect to come up with more questions that need to be answered plus some good ideas for ways to do that.