Oxyfuel Combustion - Academic Programme for the UK

如果煤燃烧发电时产生的二氧化碳能以浓缩的形式被收集起来，那么它就能被压缩成稠密的液体，并被挤入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）放在多孔岩石被非多孔岩石层密封的地方，我们可以非常有信心，其中大部分将在那里停留数万年，因此不会增加危险的气候变化的风险。但目前的燃煤发电站并不以浓缩的形式释放二氧化碳;它与大约五倍于其体积的氮气和氧气混合，这些氧气来自用于燃烧煤炭的空气。避免这种情况的一种方法是在纯氧而不是空气中燃烧煤。我们知道这在理论上是可行的，但是如果纯氧--或者说是由氧气和循环燃烧产物而不是氮气组成的“合成空气”--被用来燃烧煤炭，那么很多事情都会与使用空气不同。该项目将发展发电厂建设者和运营商需要预测和科普这些差异的科学理解。为了帮助发展对富氧燃烧的更好的科学理解，我们将在150千瓦的实验室燃烧器中进行实验。这个很小（尺寸的1%！）与真实的发电厂燃烧器相比，它将使用相同的氧气/烟道气混合物。将开发计算机模型来分析煤如何在实验室规模的燃烧器中燃烧。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，现在可以跟踪火焰中所有旋转气体和颗粒的行为，并观察它们在很小的时间间隔内如何移动和反应。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，（每秒1000帧）我们的实验室氧燃料火焰的视频记录，以了解它们如何真正流动和闪烁，并使用明亮而精确的激光束来帮助跟踪粒子如何移动，并告诉我们存在何种气体混合物。我们还在特殊的测试设备中再现火焰中发生的一些事情，以便我们有更简单的事情来衡量。然后这些测量数据进入计算机模型。煤颗粒如何首先着火，然后如何炭化和燃烧特别重要。我们也对煤灰在煤中的行为感兴趣。它可能会导致空气燃烧发电厂的墙壁涂层问题，但经过大量的经验，我们知道如何避免这种情况。其中一些教训可能必须重新学习氧燃料燃烧，帮助整理空气燃烧的专家现在开始在我们的项目中这样做。我们还在研究富氧燃烧产物如何侵蚀锅炉中使用的钢材;可能需要新材料，特别是在炎热或多尘的地区。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，当他们来建造和运营新的氧燃料工厂时，可以用来为工业提供建议。我们还将开发一些新的测量技术，用于帮助调整第一批工厂，以提供最佳性能。但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团体密切合作-国际能源署温室气体计划协调一个优秀的网络，我们也属于。随着我们了解的越来越多，我们也希望提出更多需要回答的问题，以及一些好的想法。

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.