Hello all! Awesome place we have here! I am relatively new to both hydronic heating and wood burning. I am not an engineer, but I am a damned good mechanic.at any rate i have a weil mclain gv6 "twinned" with an old style round over round wood add-on boiler. i would like to build an afterburner or reburner. i have plenty of room from the exit at the back of the woodie to the thimble. even have a nice concrete shelf to put it all on. i have access to free materiels (fire brick,plate,pipe etc) everything but the materials to make a catalytic afterburner. platinum is a bit out of my price range lol. i have been reading your forums and didnt find anything specific. apologies if i missed it. thanks in advance for any/all input.
reburner
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I am curious as to why you would need an after burner. I have operated and maintained a marine incinerator with a package oil burner located in the stack but it was primarily to burn any garbage trying to escape. It seems to me that if you want to make sure there is no unburned fuel going up the stack you should think about something simple like going with a wood gasifier. But hey, I like seeing somebody with an imagination trying to make it work. Keep us posted.
I'd read up on gasification theory. Afterburners using additional fuel are not necessary - you just need a combustible fuel /air mix coming out of your primary combustion chamber. If you do use an afterburner, you would need a way to ensure that you had enough fresh air to completely burn the unburned hydrocarbons. Just passing them through a flame is not enough if there isn't enough oxygen.
i will be able to post pics soon. the usb cale is at one of my rental units, across town. grr. my interest in attempting to reburn/afterburn/gasify the unburned fuel going up the stack is one of efficieny. i do know of the gasify units available and have decided to get one (econoburn) but its not in the budget this year. so in the mean time i thought i would "tinker" with the idea of trying to reburn the flue gasses. as i mentioned i am a pretty good mechanic, i can fix or figure out most things. basically i can build it if someone else draws/designs it. so, i am looking for ideas. thanks :}}
okay here are some pics of my current set up.
or maybe not? The size of your attachments must not exceed 350 mine is 1.7M
or maybe not? The size of your attachments must not exceed 350 mine is 1.7M
i thought technology was supposed to make our lives easier?
evidently i am ill equipped to handle posting in here. not that it matters dont seem to be getting much relevant response anyway.sorry if i caused problems with your forum.
evidently i am ill equipped to handle posting in here. not that it matters dont seem to be getting much relevant response anyway.sorry if i caused problems with your forum.
Zee, try using a site like photobucket.com. You upload the pics to that site. Then there will be options such as message board links, thumbnails, etc... It takes care of the code then all you do is copy/paste...
Glad to see you got it working Zee. Unfortunately I have not a clue how to make an afterburner. When I had a older Buderus, I looked into ways of doing the same thing you are trying. Catlyitic converters wont work because the flu temps don't get high enough. I guess that is where the extra fuel comes in. If you can figure it out and make it work safely you may become a rich man!
I think you would have better luck introducing secondary air to the fire box at the top of the boiler. Depending on how the vessel is designed as not to interfere with the heat exchanger. I found this a while ago, it may give you a few ideas... http://www.nepadigital.com/bb/post21201.html?hilit=berlin#p21201 I can not find the exact thread but a guy named Berlin modified his stove with secondary air. This link may get you started. Coal burners love to twink their stoves. Good Luck!
Well Zee, if you are a mechanic then you probably understand how a smog pump and catalytic converter work. This is how I believe you need to build your afterburner. You have to have some kind of refractory or thermal mass in the stack to keep the temps up above 1000-1200* like the platinum in cats. and pump in secondary air (superheated) so as to not cool down the exhaust. I was thinking of using a cat. converter like off a diesel truck and then place a tube in the top or bottom of the stove firebox and route it to the start of the chimney. You may also want to insulate the stack up to and around the converter with ceramic fiber blanket insulation. It will take temps up to 2300* F
good morning. i should clarify. when i said i am a damned good mechanic i did not really mean an automobile mechanic. although i have made all repairs to my vehicles over the years. for the past 20+ years i have worked in the steel erection,sheet metal and structural iron fields. i should also clarify that i would like to make an add-on gasifier. i mean something that would more completely burn the fuel that is presently exiting up the flue. my idea is to construct a "box" that could set on that concrete shelf, seen in my pics above, connect on one side to the outlet flue of the woodie. and the other to the thimble(chimney). i know, based on my own research that this is a daunting task. i have a basic grasp of the importance of the variables ( gas temps, refractory temps, air velocity/volume) but beyond that i am lost. :} so, if anyone has any ideas on how best to construct such a beast. i would gladly listen. thanks again
As Garnification mentioned PREHEATED secondary air is just the ticket. I would avoid the catalyst though as it should be unnecessary if the air is preheated well enough; for example run a stainless pipe (304 or 316) through the firebed then have it come up to the top of the combustion chamber, once it reaches the end oposite the flue outlet, drill numerous 1/4-1/8" holes in the pipe facing down, but also at random angles up to 45º (cap the open end obviously). also put an old fisher-style air regulator on the intake of the secondary air tube(s) so that they can be properly tweaked.
Berlin, Can you post the pics of your rebuild? It was very interesting. I don't know if you ever posted them here but I saw them on a different site...
I would say that your best bet is to try to increase secondary combustion inside the existing firebox, I think you'll have problems getting anything to work as an in the flue type add-on box, as there are lots of people that tried back in the "smoke dragon days" and none of those solutions really worked well.
To do that I'd also not use a cat, as they are far trickier to get going than secondary air...
I would say that your first step ought to be looking at keeping as much heat inside the firebox as you can - insulate the outside of the unit to keep the heat in the woodie, and then line as much of the firebox as you can with firebrick. If your firebox has a straight shot into the flue, try to add a baffle that the smoke has to go around to get to the flue - the longer the "residence time" in the burner, the better chance it has to burn. In addition do the earlier suggestion of adding seriously pre-heated air to the top of the firebox. The key thing to remember is that you have to keep the area where the secondary combustion will be occurring at well over 1,000*F in order to light off the smoke. A cat requires a lower temperature (~500*F, but it is tricky to plumb a cat in such a way that it has the needed airflow and smoke without subjecting it to damage from the fire itself.
Trying to do something as an after the firebox technique is going to be VERY difficult simply because it is going to be incredibly hard to just keep the smoke and air at high enough temperatures long enough to get to a reburn box.
Gooserider
To do that I'd also not use a cat, as they are far trickier to get going than secondary air...
I would say that your first step ought to be looking at keeping as much heat inside the firebox as you can - insulate the outside of the unit to keep the heat in the woodie, and then line as much of the firebox as you can with firebrick. If your firebox has a straight shot into the flue, try to add a baffle that the smoke has to go around to get to the flue - the longer the "residence time" in the burner, the better chance it has to burn. In addition do the earlier suggestion of adding seriously pre-heated air to the top of the firebox. The key thing to remember is that you have to keep the area where the secondary combustion will be occurring at well over 1,000*F in order to light off the smoke. A cat requires a lower temperature (~500*F, but it is tricky to plumb a cat in such a way that it has the needed airflow and smoke without subjecting it to damage from the fire itself.
Trying to do something as an after the firebox technique is going to be VERY difficult simply because it is going to be incredibly hard to just keep the smoke and air at high enough temperatures long enough to get to a reburn box.
Gooserider
daleeper said:
Hmmm... Hadn't thought of that, it might depend a lot on how clean the woodie burns going "flat out" and if he has to modulate it down to keep it from either over firing, or making more heat than the rest of his heating system can accept... I don't know the answer to either of those questions, but it's worth thinking about.
Gooserider
I have suggested to a few owb owners to try using storage to help get more btus and less creosote from their units.
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