I am looking into one the energy efficiency of one the most CO2 emitting processes globally, e.g., calcination. There are lots of approaches for calcination on industrial scale. I wonder whether anyone at this forum has experience with Fluidized Bed Reactors for calcination, and especially if anyone has ever tried a catalytic FBR to reduce fuel consumption and hence CO2 emissions?
Thanks
Frank
Dr. Veroustraete,
Please see the attached paper. I hope that it will help you.
We have lot of fluid bed reactors at Cranfield University and has been used in many low carbon technologies. Also, we used the fluid bed concept for calcination of limestone as part of Ca looping activity. Ben Anthony is well known in this area and is currently working at Cranfield.
Hi All,
Thanks for the info. All very relevant. I will look into your contributions attentively.
I was just wondering when asking that question whether there would not be a less polluting (with respect to fuel as well as CO2 emissions) process for calcination. I read a short article on catalytic calcination which reduced CO2 emission quite strongly by reducing the calcination operating temperature from above 850 °C to less than 480 °C. That would give a very significant reduction in fuel consumption and hence CO2 emission reduction.
If I am not wrong about 5 % of global CO2 emissions (anthropogenic) originates from calcination. There are thousands of calcination plants worldwide. We all want to make cement and concrete don't we? Hence, the CO2 reduction potential is very significant if one would be able to reduce calcination operating temperature using FBR catalytic calcination.
Worth looking into. A company which is successful in developing this type of process, would dominate the market and thereby significantly reduce global CO2 emissions as well.
Just that you know that this is quite a technological opportunity which as far as I know has not been very well looked into, nor claimed or patented, let alone tested with a small scale FBR pilot plant. I smell lots of money here guys. THe catalyst is based on Au/TiO2. Expensive catalyst no doubt, but worth trying, especially if the Au comes from recycling. I hope that Umicore is listening here.
Cheers,
Frank
Hi Kumar,
Can you check whether there have been some papers published the fluid bed concept for calcination of limestone as part of Ca looping activity? Would help me a lot to see the concept of the FBR.
Thanks beforehand,
Frank
Hi Joerg,
Thanks for the paper. Looks interesting. Hope you are doin fine!
Cheers,
Frank
https://www.researchgate.net/profile/Edward_Anthony2
Hi Frank,
Please find some papers on Ben Anthony's researchgate profile for more details. Also, you can find some first experiences on the 1.7MWth Calcium looping pilot in La Pereda.
Cheers,
Kumar
Fluidized bed reactors are very efficient in terms of heat transfers, which can most certainly be an advantage when you perform a process that requires a lot of heat. Mass transfer in fluidized beds is very dependent on the particle size, as you can read in my Thesis and 1985 Fluidization Conference paper (Copenhagen, Engineering Foundation). Also, a fluidized bed has the dis-advantage that is more or less completely mixed which can interfere with conversion targets. When calcining a soft subtance (relatively soft!) like limestone please be aware of attrition effects. Some of your product may end up in the cyclones or dust filters. In my Thesis (Delft Univ, 1985) I had a chapter on attrition measurement. I hope this information is of any use to you - at least I find it an interesting topic and a good idea to try it. If you like further advise, based on relatively old experience nevertheless, do not hesitate to contact me at Groningen University ([email protected]).
Thanks Inge-Willem,
Did you try an immobilized catalytist in the FBR, like the ones immobilized on porous ceramics to reduce the endothermy of calcination? Lots of CO2 emissions can be avoided and evidently energy consumption reduced proportionally as well, if this principle would work.
Thanks again for the good advise Inge-Willem. There are evidently a lot of aspects to be taken into account like the attrition which you mentioned. Do you know whether this issue is solved more or less in state-of-the -art FBR's built as we speak? Or is it still problematic?
Frank
Limestone as such is not very soft but after calcination-decomposition, the remaining solid is much less firm and sensitive to attrition/abrasion/wear - as I found out in my research form ca 30 years ago. Some things however never change: I am afraid this is just a material property! Solutions may be found in carefully considering the fluidization gas velocity (after some attrition, the mean particle size will be smaller so at high gas flow the finer stuff will get blown out). Since some loss via the gas flow is perhaps unvoidable, you may also consider to collect the material that is entrained in well designed cyclones as a product. I have no recent experience in fluidization research since after my promotion I came to work on many other projects none of them connected to fluidization. Still, it feel honoured that my relatively old knowledge may be of use still.
In my PhD project, we immobilized calcium to an alumina catalyst (which has neglible attrition) to capture SO2 from coal combustion. I can not judge whether the endothermy of calcination can be effectively reduced but I think it is worth trying. You could test the principle perhaps in a small scale fluidized or fixed bed already.
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