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Glycerine fired boilers
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What glycerine burning boilers available out there? I'm building a small commercial plant and had been planning on burning glycerine for process heat but have yet to find many boiler manufactures with glycerine experience. I'm needing a 15hp(500,000 btu/hr) boiler.

There's a hot water boiler from Agsolutions that may work but I was really looking for a steam boiler. Peter J Schiller Corp in NY is working on a design for a steam boiler, but has nothing proven yet.

Is anybody out there got any experience here or heard of any other companies with a boiler capable of burning this stuff?
 
Location: Texas | Registered: July 29, 2006Reply With QuoteReport This Post
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i think my burner could burn the glycerol byproduct. i don't know for sure cause i dont get much glycerol out of my biodiesel without water washing, get some left over in methanol distillation dregs, but mixed with too much water and sodium sulfate salts to burn. id burn glycerol byproduct if i had it (recover methanol first) but start the burner with wvo or biodiesel then add byproduct up to point of when you see smoke. i dont get any smoke from my burner after i turn the blower on.glycerol smoke very toxic-dont make smoke.
 
Registered: April 26, 2005Reply With QuoteReport This Post
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There are some glycerine burners being tested in the UK right now. They are designed for factory/workshop use and appear to throw out huge amounts of heat. I think they are waiting for certification before going on sale, but I'll find out a bit more.
 
Registered: September 24, 2006Reply With QuoteReport This Post
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hi!!

Bionic man....do you know if that boilers have any system or filter that eliminates the acrolein.....I think that burning glycerol is a good alternative for using this product but I am afraid of the production of acrolein that as China Sea Pirate says is very toxic!
 
Registered: February 26, 2006Reply With QuoteReport This Post
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I guess I'll answer my own question. After looking around, I would suggest talking to Agsolutions. They sell hot water boilers but I believe could also build a steam boiler. Their boilers are used in 20+ biodiesel plants and will burn up to 80% glycerine mixed with biodiesel. Seemed pretty cheap too, $8200 for 500,000 btu/hr.
 
Location: Texas | Registered: July 29, 2006Reply With QuoteReport This Post
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In my day job as a environmental engineer working in air quality for state government, we have fielded requests to use the glycerol waste stream from biodiesel as boiler fuel. The sodium content of the stream pretty much makes it a non-starter. As I recall, the typical sodium content would give a particulate matter (PM) emission rate of over 3 lbs/mmBtu. I'm told the sodium (hydroxide and/or methoxide) would convert to an oxide of sodium (Na2O2, Na20, or Na02 depending on combustion conditions) upon combustion, then combine with atmospheric water to form NaOH mist. This process is used to recycle caustic from the "black liquor" stream in the Kraft paper industry, where of course they use the appropriate pollution control equipment to recover the stuff. Our resident paper mill expert has regaled me with stories of "recovery boiler" upsets that caused this caustic to rain down on the employee parking lot, ruining the paint on all the cars. The pollution control equipment required to control the PM emissions would be prohibitive on a small scale.

When you add up the following:
1. Sodium particulate emissions
2. Possibility of acrolein emissions
3. Lack of experience operating a boiler firing this material
4. Lack of comprehensive knowledge of the pollutant emissions from burning this stream..
you'll have a hard time getting air quality regulators to approve the use of the glycerol waste stream as a boiler fuel.

brbd


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Location: Raleigh, NC, USA | Registered: June 19, 2003Reply With QuoteReport This Post



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Do you think a similar thing would happen with KOH catalyst glycerine? i.e., K2O formation, reacting to form KOH mist?
 
Location: Southern WI, USA | Registered: May 18, 2006Reply With QuoteReport This Post
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quote:
Originally posted by Ryan P.:
Do you think a similar thing would happen with KOH catalyst glycerine? i.e., K2O formation, reacting to form KOH mist?


I just edited the previous post to correct my reference to NaO.

I think sodium and potassium combust similarly:
Combust at Low O2 -> oxide formation (Na2O, K2O)
Combust at "Normal" O2 - peroxide formation (Na2O2, K2O2)
Combust in high O2 -> superoxide formation (NaO2, KO2)

In a glycerol waste-fired boiler you'd probably get some of each oxide. All of the various oxides form the respective hydroxide with water. If there's an anion present in the fuel, such as SO4- or Cl-, you'd also likely get formation of the corresponding salt (i.e. NaSO4, KCl) as fly ash or bottom ash, but I don't know how that reaction would compete with the oxide formation.

brbd


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Location: Raleigh, NC, USA | Registered: June 19, 2003Reply With QuoteReport This Post
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OK, one more thing. There are people who make glycerine logs (byproduct soaked into wood chips/sawdust/etc.) that they throw on campfires, wood stoves, etc once they are good and glowing hot. They avoid the acrolein formation this way, but your thinking they still produce "caustic mist".
 
Location: Southern WI, USA | Registered: May 18, 2006Reply With QuoteReport This Post
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The glycerol logs are burned differently than liquid boiler fuel. Liquid fuel is atomized or sprayed into the firebox which has combustion air flowing through it. That tends to keep the combustion products suspended in the exhaust gas. Solid logs burning in a natural draft (i.e without a fan-forced or -induced draft) would likely produce more "bottom ash" and less "fly ash". Folks used to get their lye for soapmaking from wood ashes. I would suspect the ash from glycerol logs would be a lot more caustic than regular wood ashes, though there may be some Cl- or SO4- in the wood chips/sawdust to form salts.

brbd


1986 VW Golf 1.6NA
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Location: Raleigh, NC, USA | Registered: June 19, 2003Reply With QuoteReport This Post
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I wonder if an oil burning foundry furnace would adequately burn byproduct.

The combustion temperatures are *hot* and any stuff that drops to the bottom would land on a refractory surface >1500 degrees.

http://www.metalwebnews.com/howto/furnace2/furnace.html
 
Location: Montesano, WA | Registered: October 31, 2006Reply With QuoteReport This Post
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quote:
Originally posted by lumberjack_jeff:
I wonder if an oil burning foundry furnace would adequately burn byproduct.

The combustion temperatures are *hot* and any stuff that drops to the bottom would land on a refractory surface >1500 degrees.

http://www.metalwebnews.com/howto/furnace2/furnace.html


Well I'm no chemist but I don't think you can burn sodium at any temperature.. it changes but its still sodium.. Sodium is an element and as I understand it, the only way to get rid of an element is fission or fussion.. IE: change it to something else.

In other words, it doesnt really matter how hot you get the glycerin.. the byproducts of combustion are bad news in the way of being very caustic..

or am I not understanding something?


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Registered: March 09, 2006Reply With QuoteReport This Post



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OK, here is one thing I don't understand, both of the hydroxides are dangerous because they are highly reactive. But doesn't this high reactivity also makes them rapidly pick up carbon from the air and rather quicky turn to nice, neutral sodium bicarbonate or potasium bicarbonate? Baking soda, basically?

How rapidly they "degrade" into other neutral compounds is part of the reason you have to keep your catalyst containers sealed and dry and why some guys go so far as to vaccuum seal quantities for longer term storage, right?

So unless its actually raining and your exhaust is dissolving in the rain immediately after exiting the smoke stake, isn't it going to neutralize with atmospheric CO2 rather quickly?

I know just enough to be confused...
 
Location: Southern WI, USA | Registered: May 18, 2006Reply With QuoteReport This Post
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sounds like a fair point; especially as heat speeds reactions...

Regarding acrolien. You won't get it if you have flames rather than smouldering so it should not be a problem in normal operation. Bear in mind that you should be working at 850 deg C plus to burn glycerine cleanly.

Regarding the salts you can pretreat the byproduct, to remove most of the caustic as a harmless precipitate, using acid.

Some of the precipitate will remain dissolved in the glycerine I am told but the byproduct will also seperate into two layers. The top layer is a mixture of biodiesel and FFA and conatains no sodium or pottasium salts, or so I am lead top believe. The middle lowwer layer is glycerie, more or less pure with salts dissolved in it; again, so I am led to believe.

Seems like there is scope to mitigate any potential emmisions and highlights the need to distinguish between byproduct and actual glycerine when discussing what to do with it. Byproduct is a mixed variable waste stream. Glycerine is a single product when pure.
 
Location: Manchester UK | Registered: June 03, 2003Reply With QuoteReport This Post
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Ant,

where did you get the 850C figure? I see people throwing around all kinds of numbers like that but haven't found what the source is. My half-hearted research on this (mostly chatting with a biomass energy burner engineer who's looked at glycerine combustion a bit, and Neutral's posts saying that acroleine has a distinctively noxious odor) has led me to tell people that the important factor seems to be to give the burner enough oxygen- I dont' worry about checking the burner temperature. But I see people get really hung up on 'which temp is correct'. Can you shed some more light on this, ignoring the sodium issue?

Hi, BRBD- I think we met in Iowa a few years back? I can't remember your real name though, sorry! Interesting info on this thread. Any idea how some of this exhaust can be tested in a lab or real-world environment?
 
Location: Pittsboro, North Carolina | Registered: March 07, 2001Reply With QuoteReport This Post
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You only need to exceed the boiling point of glycerine and maintain flames to avoid acrolien; well below 850degC, 290DegC boiling point. Auto gnition temp is 370deg C so that would be a good temp for avoiding acrolien.

850degC is to provide complete combusion without crud left over, Clean Burn. No idea now where it came from but I am 99.9% confident of both he figure and it's releavance. Of course my source could have been flawed...

try searching the forum for 850 using the google search and see what comes up.


mathematical elegance -- desired result achieved with minimal complication
 
Location: Manchester UK | Registered: June 03, 2003Reply With QuoteReport This Post
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I heard today about glycerine being sold to cement kilns (industrial).

farmer
 
Location: Chambersburg, PA | Registered: January 01, 2001Reply With QuoteReport This Post
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Yeah maybe. cement kiln fuel uses a mixed solvent waste stream. Whatever they can get I think.

I expect they would be happy to burn anything they can get cheaply and are well capable of maintaing the temps needed for a clean burn.


mathematical elegance -- desired result achieved with minimal complication
 
Location: Manchester UK | Registered: June 03, 2003Reply With QuoteReport This Post



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After some searching I have found the following post that I was a part of...

http://biodiesel.infopop.cc/eve/forums/a/tpc/f/739605551/m/2841051601

Homestead says:

"I built 3 glycerin burners before I got one right. Seems that glycerin burns above 850 degrees, and a lower temperature leaves the black gunk. So the last burner is masonry lined, to retain the heat. It has to be fired with a babington burning vegetable oil, and when hot the glycerin is added to the stove as a separate stream"

So it seems my Brit brain auto added deg C from memory and as a Yank he could have meant either.

So the actual temp could be 850degC or 454degC.

To summarise what I know about burning glycerine so far:

It can produce acrolein if you burn it badly with smouldering smoke.

Very toxic.

This starts at around 290 deg C which is the boiling point and where thermal decompostion takes place. http://nationaldiagnostics.com/images/HS-106.pdf

It will however vaporise and burn at temps between 130 deg C and 264 deg C.

Auto ignition temp is 370 deg C so it can certainly be burnt safely at that temp or above.

It can still leave unburnt residues when it burns though. This may be more due to impurities in the glycerine than the glycerine itself.

Sugar and dextrin for example.

It depends partly on whether you intend to treat the by-product with acid to convert the soap to ffa or not.

Experiments by Homestead indicate a temp of 850 deg leaves no residue with simple un treated by-product.

He neglected to say if it was deg C or deg F. So it could mean 850 or 454 deg C.

Soaps are the issue there so I would not like to speculate without further research or info from others who might know.

There is a lovely 1898 article on glycerine you might like to read. It is where I got the vapourisation temps and impurity info from.

http://www.henriettesherbal.com/eclectic/kings/glycerinum.html


mathematical elegance -- desired result achieved with minimal complication
 
Location: Manchester UK | Registered: June 03, 2003Reply With QuoteReport This Post
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Ant, I think the 850C probably comes from WID
 
Location: Ashford | Registered: March 12, 2001Reply With QuoteReport This Post
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