jacob
New Member
Posts: 14 
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Post by jacob on Jan 14, 2014 23:25:00 GMT -8
I am planning on casting some cook stoves in 5 gallon buckets for outdoor use.
I was wondering, if I mix perlite or vermiculite with portland to lighten it up and give the burn tunnels and riser more insulating properties, does the perlite or vermiculite send small glass particles in to the air while cooking that one could inhale, or that lands in food? Or does it simply "glassify" from the heat?
For my outdoor cookstove experiments I want to use inexpensive materials since I will likely be filling up several 5 gallon buckets willy nilly trying different things.
for my indoor heating RMH's I plan on using hi quality insulating refractories in all cores and risers.
My outdoor stoves I was planning on trying different diameters to create different size "burners". But all in same size 5 gallon buckets. Since the feed tubes and risers will be same length in all of them, will the burn efficiency change as the diameter changes?
Also, will I get better burn efficiency if the back of the burn tunnel is rounded? Or 90 degrees. Also difference in rectangular air path, as opposed to round? If rectangular is better, I could use rectangular gutter for inner forms.
Thanks.
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hpmer
Full Member
Posts: 240
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Post by hpmer on Jan 17, 2014 7:54:57 GMT -8
I can't answer some of your questions, but can say that the output improves dramatically with increases in size.
For example, a 6" will be much more than a 50% improvement over a 4".
I've been disappointed with anything below 4" (and I will likely never build anything less than 5" in the future).
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Post by Donkey on Jan 18, 2014 0:03:35 GMT -8
I am planning on casting some cook stoves in 5 gallon buckets for outdoor use. I was wondering, if I mix perlite or vermiculite with portland to lighten it up and give the burn tunnels and riser more insulating properties, does the perlite or vermiculite send small glass particles in to the air while cooking that one could inhale, or that lands in food? Or does it simply "glassify" from the heat? Firstly, don't use portland. It can't handle the heat and will crumble very shortly. You might get a burn or two out of it before it does.. Maybe. You want clay. Locally sourced, dig-it-up-for-free clay is what I prefer, If you can't find something appropriate near you, then buy fire-clay in bags. Make clay slip, mix it with the perlite, pour (pack actually) into forms, let dry and fire in-situ (as you use it). If you plan to trap all of your cook-stoves inside buckets, you will find a sweet spot (in width), (4 or 5 inches maybe) much larger than that will want to be taller than the bucket will allow. I like 6 inch cookers, but you need to stack a second bucket to hold it in that way. Both round and square will work.. There are issues with square pipe, dead space in the corners making for a smaller column than is readily apparent. You can round the back, but you do want a certain amount of turbulence for fuel/air mixing. If you round things off too much, you'll have to build in a different way to mix or risk dirty burn. |
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jacob
New Member
Posts: 14
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Post by jacob on Jan 20, 2014 19:14:32 GMT -8
Both round and square will work.. There are issues with square pipe, dead space in the corners making for a smaller column than is readily apparent. You can round the back, but you do want a certain amount of turbulence for fuel/air mixing. If you round things off too much, you'll have to build in a different way to mix or risk dirty burn. What if I "square" the back? I thought turbulence was a result of air forced through angular airpath. There is a lot more round material available for forms than rectangular. Especially if I want to burn it out, cardboard usually comes in round tubes. If I use a round riser form cut at 45 degree angle, which meets a round burn tunnel form cut at 45 degree angle, will the 90 degree angle create enough turbulence with round air path? Or would it be good to have use a rectangle on the bottom, and round riser coming down to meet it? I was thinking of skimming the bottom/ sides of the burn tunnel with pure refractory to prevent breakdown of perlite particles flying into airpath after being chipped off by wood scraping the bottom sides. skimming the botom of the burn tunnel would be much easier if burn tunnel was rectangular. |
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Post by woodburner on Jan 23, 2015 6:50:13 GMT -8
Have a search in the experimenter's corner. Look for Peterburg's info on J-tubes. You will find some revelations which show how complex these simple looking tubes get when they are built for optimum performance. Maybe cunning is a better word than complex.
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Post by patamos on Jan 28, 2015 9:47:59 GMT -8
for 5-gallon buckets i have found a 4" Winiarski L-feed to be a good way to make the most of the short heat riser. Although a j-feed is nicer in many respects, i haven't gotten one to pull as well in that short a system. I have been playing with ways to keep the wood vertical without having to draw the air down from the top of the feed tunnel, but haven't got it dialled. Perhaps other folks had figured it out.
Otherwise, there are 7 (or so) gallon buckets out there that may be more ideal
To keep the riser as tall as possible, I have been placing only 1/2" of ceramic felt under the burn chamber, and setting the bucket up on 1/4" shims to allow airflow below.
Once the chambers are formed, mixing sodium silicate with fine sand and a bit of water to create a creamy putty, and applying it by hand onto the walls is a good way to create a thin hard shell. Clay and fine sand works pretty good too. This is also a good way to anchor in the pot rests
just rambling...
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