I saw recently that another group at Chalmers have found that by replacing the sand in a fluidised bed combustor with an iron mineral (ilmenite) that they got the furnace to perform better. This reminds me of how many car exhaust catalysts include some cerium oxide in the washcoat, the idea is that when the engine is running lean that the cerium oxide absorbs oxygen from the gas mixture and it is able to release it when the engine runs rich for a moment.
When I get the chance I will look up the crystallography of ilmenite, I would like to know how well cerium dioxide would work as a replacement for this iron mineral. I do not know the melting point of ilmenite but I know that cerium dioxide is a solid with a very high melting point. I know it makes a reasonable surogate for plutonium dioxide. I know that some people hate the idea of working with surogates (they say you must always use the real thing), but I would say that a surogate is a useful thing which allows you to test methods and equipment at a lower cost. The use of the model compound should then be followed with a test with the real thing before moving to an industrial scale.
But back to cerium dioxide, I know it should not sinter with great ease. I know that one of the problems with fluidised beds is that if the sand starts to melt or sinter then it will cause chaos in the boiler. With some luck I will be able to tell you something about this issue some time.
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