Fluid Bed Calcination

Hi Guys,

I just wanted to take a moment to talk about fluid bed calcination. As you know I work with he calcination process engineering groupfocused on improving, developing, optimizing and scaling up calcination processes. For alot of us here that means rotary kilns or roller hearth, but those arent always the best solution and I want to make sure we're considering all the options and possible benefits

First lets take a step back and consider calcination reactions in general, what are our goals and limits. "Calcination is the CONTROLLED application of TIME, TEMPERATURE and ATMOSPHERE to produce a PREDICTABLE CHANGE IN A MATERIAL". Lets think about that, control time, temperature and atmosphere. That usually means getting a defined amount of energy, as heat, into a product for a defined time and in defined atmosphere. Temperature, a minimum is required to drive reactions, but too much temperature can mean at best wasted energy, at worst ruined product - so the temperature should be tightly controlled. The atmosphere often can drive reactions too, for oxidation or reduction, the gas phase is part of the reaction, and diffusion may limit the rate. Other times the gs flow just carries away gaseous products. But again ensuring the product all sees the same atmosphere conditions makes more homogenous products. Finally time is usually a minimum required for the atmosphere or temperature related rate - the faster we can go that means throughput, productivity.

Now, for those of you unfamiliar, fluid bed involves upflowing fluid, usually a gas, and particles are suspended in the flow in a chamber. It's used often for granulation where the random flow and homogeneous distribution allows simple granule formation, and also for drying because the high gas/solid contact greatly speeds up both heat transfer to the particles and diffusion of water away to accelerate drying.

Fluid bed calcination involves temperatures up to around 8-900C, at which point materials of construction start to become a significant concern. the preheated gas comes up though a specially deigned distributor plate which fluidizes the particles. The major heating action is by the preheated air, which is in intimate contact with the suspended particles, ensuring high heat transfer both to and away from the particles. Because the inlet air temperature can be controlled tightly and the residence time of the fluidizing gas is low, the fluid bed allows tight control of the temperature, both heating for very homogeneous product, or cooling when exothermic energy needs to be controlled. Additionally when the gas diffusion limits the reaction, as is the case for drying or for example reduction reactions, again the intimate contact and high rate of gas turnover can dramatically accelerate reaction rates and ensure the entire batch is seeing nearly identical conditions. Cool!

Re: Fluid Bed Calcination

So lets compare that to other technologies.

Probalby the most familiar are rotary and roller hearth or saggar-based

In a rotary your material is rolling down a heated tube. Most of your heat transfer is through radiation of the tube and conduction from physical contact with the tube. This often has fair to good mixing, depending on how turnover is mixing it, lifters/flights or otherwise. and turnover ensures even temperature so that the bed sees nearly the same conditions. However that same mixing also means that the time may be short (bypass) or long, (backflow). This leads to a gradient of time with a narrower temperature distribution, and can make some both over and undercalcined material, usually the tolerance of this is made up once the product is blended. Gas phase interaction is poor to fair, (as seen in models by yanxiang xi) the gas by buyoancy rises to the top, while the product sits at the bottom. As a result the gas bypass is high, and only the top surface of the bed sees the furnace atmosphere, and the gas by the surface can be depleted off reactant or saturated in gas products.

Meanwhile in a roller hearth kiln, you have excellent control of the time, each sagger stays in the furnace for rigidly defined periods. However because of the thermal mass of the sagger, transfer through surfaces with poor heat transfer in the bed, and relatively stagnant flow in the product bed, the temperatures seen over the course of a pass may be very different from the edges to the center.

Contrast this to the fluid bed where batchwise operation ensures direct control of the time, and the high gas solid contact and rapid fluidized mixing enables direct control of the temperature and environment each particle is exposed to, with fast heat exchange and fast changes of the near-surface atmpshpere both thermal and diffusion limited reactions are accelerated and better controlled for consistent homogenous product.

Re: Fluid Bed Calcination

Dirty30 Dillon /

I wish I could understand any of this.

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Casting aluminum?

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He works in a cheese factory and thats the way you homoginize the milk.

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me:

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Fracking?

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There are two relevant examples I could share of this but won't. However one example might be the calcination of a ceramic material which contains binders. In the manufacture of the material it is impregnated with plastic based resins which hold it to it's shape. In order to finish the product it must get calcined, or cooked, but if it gets over-cooked it ceases to work. The problem with traditional routes is that the energy released when the resin burns rapidly overheats the material and overcooks it, but that resin still needs to burn. This is managed by very slow rates to ensure complete combustion without overheating.

In a fluid bed the gas phase is quickly exchanged so that the energy from the combustion is drawn away, and further the atmosphere can be controlled with low oxygen so there's both more diluted air to act as a heat carrier (this is the basic reason that oxy-acetylene is hotter than a torch in regular air - the extra inert nitrogen present that also needs to be heated and takes up some energy because of the oxygen dilution) but also there's less oxygen available to delay the rate of reaction. In this manner the temperature is closely controlled while still getting the resin combusted and removed in a rapid manner.

Likewise another material may be very sensitive to oxygen, more oxygen favors the final product. better mixed it can react faster. for a more energetic example compare lighting a puddle of gas to lighting a mist of gasoline. WHoosh! one's much faster because the oxygen needed to react is more readily available! If you need that oxygen to contribute to reactions with a solid, again it's much faster in the fluidized case leading to savings and increased productivity! DOPE ON A ROPE that's some hotboy shit

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Other topics that could be interesting to discus are how to make it continuous, existing fluid bed units and processes in-use in the world today and how they could be better, or the need for additional study and development of the technology!

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> Born to be WillD Wrote:

> -------------------------------------------------------

> Other topics that could be interesting to discus are how to make it

> continuous, existing fluid bed units and processes in-use in the world

> today and how they could be better, or the need for additional study and

> development of the technology!

I've got a better one involving a fluidized bed for creating uranium oxide out of off=gassed nuclear material of low assay.

Can't really go into detail though. It's a patented process.

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patented you can go into lotsa detail, it'd be publically released at that point. can probably google it - But yea that sounds like one where the high gas contact helps oxidize the material, while the high airflow helps limit the exotherm (assuming its exothermic) from oxidation, to get to a relatively inert uranium waste. Or you use the uranium oxide? dump into ducrete

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I do this when I have to give a random presentation, it helps organize my thoughts into a coherent story to just sortof tryn talk through it to yall. thanks fellers

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> Born to be WillD Wrote:

> -------------------------------------------------------

> patented you can go into lotsa detail, it'd be publically released at

> that point. can probably google it - But yea that sounds like one where

> the high gas contact helps oxidize the material, while the high airflow

> helps limit the exotherm (assuming its exothermic) from oxidation, to

> get to a relatively inert uranium waste. Or you use the uranium oxide?

> dump into ducrete

NO air allowed,Will……………..KA-BOOM! A scientist from Washington owns the system. DOE bought it from him.

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You lost me at Hi guys.

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> Don Ohio Wrote:

> -------------------------------------------------------

> > Born to be WillD Wrote:

>

> > -------------------------------------------------------

>

> > Other topics that could be interesting to discus are how to make it

>

> > continuous, existing fluid bed units and processes in-use in the world

>

> > today and how they could be better, or the need for additional study

> and

>

> > development of the technology!

>

> I've got a better one involving a fluidized bed for creating uranium

> oxide out of off=gassed nuclear material of low assay.

>

> Can't really go into detail though. It's a patented process.

Lol once something's patented it's out there for all to see, it's one thing firms have to consider when deciding if they want to patent something. Give me the patent number and I'll summarize it

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wow you are in deep...my fam are wife masters, youngest D masters and oldest D bach.....with my limited understanding in the procedures. the successes are limited to production vessel. my guess is Quartz as a tunable material that can handle the criteria of calcination.....did i win?

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It's patented in general, but proprietary info. is classified. Surely you can understand DOE keeping proprietary info.?

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> Don Ohio Wrote:

> -------------------------------------------------------

> It's patented in general, but proprietary info. is classified. Surely

> you can understand DOE keeping proprietary info.?

Proprietary and patented are mutually exclusive so what you said really doesn't make sense. It's not patented if it's proprietary, or else it wouldn't be a secret. I understand the reasoning behind keeping info proprietary; I'm trying to go to law school for patent law

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Well, maybe the scuttlebutt at work that it WAS patented was wrong. I signed DOE non-disclosure to work there, and I'm not gonna disclose.

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I worked for the DOE for a while at Oak Ridge. Most all of that work was published just because public funded work by definition gets shared. Gotta make sure public funded works are publically available in general. the nuclear stuff is pretty tight lipped though I think for the potential that people use it for more nefarious purposes.

If it's waste treatment I'd expect they wanna protect the non-patented parts upsteam from exposing details about the waste?

As far as quartz, definitely really common reactor material, very inert. Also you dont think of glass being that high temp but pure quartz will outlast most metals at highT, good and inert - except unless it's containing a glass modifier - which urania can be. any salts get pretty bad too. My guess would be if they're really trying to keep it oxygen free it'd be graphite lined, or you make the lining with uranium - its super expensive but not uncommon for the real high performance heat treatments

Re: Fluid Bed Calcination

> Don Ohio Wrote:

> -------------------------------------------------------

> > Born to be WillD Wrote:

>

> > -------------------------------------------------------

>

> > patented you can go into lotsa detail, it'd be publically released at

>

> > that point. can probably google it - But yea that sounds like one

> where

>

> > the high gas contact helps oxidize the material, while the high

> airflow

>

> > helps limit the exotherm (assuming its exothermic) from oxidation, to

>

> > get to a relatively inert uranium waste. Or you use the uranium oxide?

>

> > dump into ducrete

>

> NO air allowed,Will……………..KA-BOOM! A scientist from Washington owns the

> system. DOE bought it from him.

I heard about this on Art Bell, I think.

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and just like that. He was gone...

giphy-44.gif

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At temps of 1100 C degrees, `POOF' is very possible, Pot.

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I once instinctively reached out and momentarily touched a metal sample at 1300C. my finger burst into flames instantaneously. it was wild, like there was a little candle flame that was my finger burnng. it didnt even really hurt, seared it

still it was wild to witness a flame of my own body physically combusting.

Anyway, gave this presentation just now. crushed it. thanks yall.

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I once did the opposite wearing leather gloves, while trying to locate a liquid O2 leak I the `snow' it had created in the area. FOUND IT! YIPES! If it hadn't been for that leather glove, they'd have called me `nine fingers'.

As it was, it froze my finger at the tip and I was worried,but circulation came back.

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Overpriced Parts /

> Don Ohio Wrote:

> -------------------------------------------------------

> I once did the opposite wearing leather gloves, while trying to locate a

> liquid O2 leak I the `snow' it had created in the area. FOUND IT!

> YIPES! If it hadn't been for that leather glove, they'd have called me

> `nine fingers'.

>

> As it was, it froze my finger at the tip and I was worried,but

> ut circulation came back.

Yeah some of that liquid gas is super cold!

While working at the cleve clinic, research building all the huge gray liquid nitrogen cryo-genic storage containers/liquid nitrogen containers that were supposed to be moved before we could do the demo, of the lab flooring (that was ruined by them to begin with because they dripped the stuff on the floor on every time they got some out)

After hour of calling everybody we could think of at 6:30 in the morning no one knew what to do with these huge 7-800+ pound containers that the wheels are basically stuck into the flooring,

Finally some research doctor who was is the size and wt of a 12-year-old kid (like 110 pounds) and was very hard to understand and didn’t understand what we were doing at around 7:30 in the morning said he would get his team to move them but his team of four barely weighed a bit more what one roll of our linoleum Weighed,

So we started to bring in 2 meter wide Forbo real linoleum from the Netherlands that weighed 200 to 220 kg per roll,

It was very difficult on a two wheel dolly with one man (not really for me though because my dolly was perfect and I weighed 200 pounds the time) down the hall that we were supposed to use and cannot be blocked due to fire concerns) to move a big roll of Lino to begin with and we had several rolls, glue and other equipment and supplies

This research doctor guy’s team of 4 people probably didn’t weigh 240 kg when all put together so they could barely move these huge containers so they just put them outside in the hall that wasn’t supposed to be blocked,

It was very hard to get by those huge containers and other crap they put in the hall blocking the hall with stuff staggered everywhere while carrying almost foot seven foot wide (well 7’ tall on roll with wrapping material) 200-220 kg material,

Well someone lost a 218kg roll and it fell hitting into one of those unsecured liquid nitrogen Cariogenic containers that had a loose lid lid to begin with and some spilled on the floor and wall as well as messing up whatever they had inside of it, (man some of these research people are book smart but not not street smart, moving smart or any common sense smart)

Man that Lino roll completely destroyed a 2 x 3 meter part of the hallway flooring and a 1st year apprentice moving the end of linoleum to get it out-of-the-way he got some on his glove and ended up getting some frostbite blister damage on a few fingers but some masking tape took care of it ha ha,

The first 6 layers of that 212kg Roll of Lino were completely destroyed cracked/pulverized beyond belief making us come short on the amount of square yards/meters we had to do to finish the job,

Book smart means nothing if you’re not street-smart and survival smart!

You would think that somebody with eight years or more of college wouldn’t think that something cold could could be very hazardous but they act and they always acted like it was nothing when they destroyed floor wall and counter surfaces due to their spilling/miss handling of liquid nitrogen!

I mean it was good that that these PhD’s peeps give us more work but man these research people were so stupid, leaving broken test tubes on the floor with who knows what was in them, leaving hoods open contaminating work areas, pouring toxic waste in the wrong drain causing plumbers and pipefitters to get malaria and other diseases,

I mean no clue, in a research lab you have two different water supplies and two different drains,

These eight year PhD research doctors had no clue after eight years of education which ones to use as well as eating their fish bait lunches right in lab area!

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We used to use liquid nitrogen to cool our beers. You couldn't put the beer into it, itd cause ice to form little crystals on the inside that were perfect nucleation points for bubbles to form, kinda how mentos work in diet coke, and its definitely overflow dramatically when you opened it. Nah, you dump it straight in the beer, it's like putting ice in it but it's just nitrogen so it evaporates and you're left with a quick chilled cold one!

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That's some helpful knowledge for if i ever get in a situation where there's liquid nitrogen but no fridge.

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I felt intimidated but I wanted play along. Thanks, and glad you crushed it. I kind of knew quartz was too fundamental for the procedures. I was on the machinists end of things. I made parts out of a lot of materials, graphite being one. With the large variety of materials machined, I did my best to interpret the applications of these parts I made.

8552CCDC-5F83-4DB5-9AD7-96CEE9CBE326.jpeg

Pic shows one actual part I made. The extra came home with me as it looked to be a nice oney. The rest was crap I made on my lunch hour out of landfill.

Re: Fluid Bed Calcination

> ID OD Wrote:

> -------------------------------------------------------

> Pic shows...

Still love all the arrowheads, do you have any stone/flint axes?

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