Alexis Hamels wrote:Thanks for all the answers so far.
It becomes clearer to me what I need to do.
I'll take the information to a local stove-builder and see what comes out of it.
The wall is made of red brick. I suppose it conducts the heat well, so that it radiates on both sides. That's what I wanted to make sure.
Another concern is how much fuel it would need. I definitly don't want to have to feed it all day long.
As a nice first job, I should problably best build a small standard rocket stove and experiment with it. I can see that now.
Consider - the smaller the rocket, the more time it'll have to burn. And smaller rockets take more tending.
ETA: I wrote that thinking you meant 'small ... rocket stove' feeding the bell/wall, but on rereading I guess that's not what you meant.
If you do away with the coil you're moving away from the double boiler. It could be OK if the pot is not closed - pump water into it and let it overflow. If the pot is closed and it gets low you might have a problem (bomb).
Having your flue gasses in contact with the sides of the pot gives a lot more area for heat transfer. The chimney probably improves draw but you could also set it up with an open top (with proper gap) instead. Go to
http://www.aprovecho.org/lab/rad/rl/stove-design/category/1 and look at items 5, 8, 19, and any others that may catch your eye.
First, the 'double boiler' method is much safer. In your pic I see a couple things "less than optimal". The inside of the heat riser is not the place to take heat from. Let the combustion complete or you'll get soot and/or creosote in the rest of the system. And your water flow is backwards, you want the cooler water in contact with the cooler gasses - flowing hot water past the cooler gasses is not productive. But exposing the piping to the intense heat makes things critical. Pump failure is not an option, the water will flash to steam and likely blow a pipe apart. Mineral buildup may become a problem, depending on your water.
Byron Campbell wrote:Yes I believe you've got a good handle on it Rob. The way the system is described in "the book", the two barrels are joined by their ends that would normally accept their removable lids (joined lip to lip with the standard barrel band clamp). So in your application one option would be to cut your top barrel to length with clamping end intact. Then close the cut end with a welded on lid, or even make one from a disk of heavier gauge steel for a nice heavy cook surface.
Here's another idea that may help you avoid the welding chore. Common 55 gal. drums have two molded in strengthening or stiffening bulges encircling their circumference, one at about 1/3 the barrels length and the other at about the 2/3 point. If the barrel was shortened by cutting it at the apex of one of those molded in bulges it would make for a nicely flared opening to facilitate clamping to the other barrels lip. Best to try this out first with a scrap barrel.
As to the gasket to seal the two barrel sections together, Wisner mentions using fiberglass woodstove door gasket, high heat foil tape, then the original ring clamp (band clamp).
That's what I was thinking but it might fit better against another apex (cut the barrel just above one). The clamp has a V shape doesn't it? Been a while since I looked at one.
My insurance also says I have to have a UL approved woodstove. By the time I get one of those and a professional installation it will take a long time to break even. Value of the mobile home is about nil anyway, and my personal possessions are not documented. The main reason I keep insurance is liability, so if I do install a wood burning device I figure I'm on my own and I'm careful. They didn't give me fire insurance on the garage anyway.
I do try to follow codes where it's practical, but last time I installed a flue to code, the code changed shortly after.
I can't imagine a 0.4 carbon file being useful for long, even in wood. Files aren't specified for use other than coarseness AFAIK (you wouldn't want to use a rasp on metal in most cases but double and single cut work fine on wood). One that I recall reusing for a hot cut was a 1" wide Nicholson single cut mill file. Most wood tools are high carbon steel, with 0.4 carbon content you really don't get much hardening. I don't expect spike knives to hold an edge very well, and I don't bother with tempering.
Here are some spectro analysis of files, about the middle of the page:
I'm not sure what you mean by most of the carbon being at grain boundaries or how they would be 'liquified'. At forging temps the grains are consolidating and growing, but hammering breaks them down. The carbon migrates around until the metal cools, and can get trapped within the iron crystals if cooled fast (quenched).
Looking around the 'net I can't find much pertinent, but it seems iron has a much greater 'affinity' for sulphur than carbon and it forms iron sulphide, which is a better explanation IMO. In this piece:
the 5th paragraph echoes what I was saying about the fire and 6th paragraph talks about the condensing smoke. I have seen that advocated as a finish. However when he talks about steel absorbing carbon from the fire I wonder. I think that lies somewhere between "unproven" and "wives tale" which smithing has more than it's share of. That's why I had wondered about absorbing sulphur.
and this here looks pretty promising and awesome. thanks for posting! (should have looked at you link right away)
the look makes me instantly think of a bloomery (which is basically a rocket stove with extra air blown into it, that is fuel-fed from the top)
is there already a way to regulate the fire? would you say it needs more fuel than a regular rocket? would you mind maybe posting a crosssection sometime?
great inspiration anyway...
it is the final straw for me. i am just gonna build a prototype myself as soon as possible. (and then i can find out how much of a problem the sulphur will be for my purposes, if it has enough power and so on...)
maybe to build it like a bloomery isn`t the worst idea. the forced secondary air could provide a means of regulation, too.
i don`t know how easily the sulphur stuff compares to carburizing, because sulphur is already fatal in traces whereas you need significant amounts of carbon to make temperable steel; also for most works including tool steel you have to reheat more often and often use only thin sheets that than get welded together, but do expose a lot of surface before. and as i said before, for ornamental stuff and non-load bearing funktional stuff like your scoop made from regular construction steel this is probably never a problem. maybe it isn`t for any purpose. it`s just that i mend a lot of tools and during the beginnings of my apprenticeship i wrecked a pickax (my own pickax i wanted to fix after work) and was told it was because i had used fresh coal. then, when i started making knives a few years ago i experienced "red brittleness" on my first try with welding high carbon sheet steel on an anthracite fire. i changed to charcoal or charcoalmix for these purposes and never had any problems since, but the burnt child dreads the fire...(or the sulphur)
and you wouldn`t need to take material of, because the problem only occurs with "red" heat. i guess you already know about the structure of steel; "red brittleness" is caused by the lower melting point of the sulphur-carbon-compound on the grain-boundaries.
I had the gasifier regulated with a shutter over the blower opening, set so there was 1/8" crescent (out of a 2 3/4" hole) opening. Basically using very little of the blower's capacity. As I recall, more opening didn't help. After the blower box I had a divider box to get most of the air to the secondary 'jets' (holes). If I were to set it up again I'd do something like this:
but with as little metal as possible. Regulating voltage plus the butterflies should give great control (the upper fan needs a larger duct too). I used a 3" throat, a bit larger would probably be a good thing. A more insulative oven might help too. I used mud/perlite/straw with a couple brick pieces to reinforce the sides of the opening. There was also a 'mousehole' in the back I could cover with a brick. It took a while (1/2 hr) to get up to good temp and glowed for a while after shutdown.
I can't compare it to a rocket as I haven't tried such a thing for forging (and I think the excess air would be a big hindrance). But gasifiers burn fuel completely, there was never much ash to clean out even after a long day. I never noticed any ash other than from paper being blown out but I can't imagine where else it went.
I have seen sulphur condense on iron from the fumes of green coal, I know what you're talking about. Fire management... but in most cases that means having some coal 'coking' around the edges of the fire and no guarantee the sulphur is not drawn into the fire - especially when you stop feeding air from the bottom. Making enough coke beforehand avoids that. Now you have me wondering. I made some tools from files and haven't had any trouble with them. Then again I've never smelled anything like green coal fumes coming from my gasifier.
I've made a couple primitive knives with the forge finish right up to the edge, but I was thinking most knives and other "good" work are finish ground/filed. From your experience the problem goes much deeper anyway, so moot point.
I know about the various stages of coal/coke in a forge fire but it's impossible to fully control where the sulphur goes in the fire.
This is more like a gas forge than a coal forge, but I built and ran this for almost nothing (mostly salvaged parts). I'm sure it could be refined, and would need to be for professional use. With a single iron there was some waiting but two would keep you busy.
Won't reach welding temp as is (camera makes it look hotter), but the upside is it won't burn steel. Considering how hard it is to get carbon to migrate into steel (see case hardening techniques) I'm not worried about sulphur at this temp. How far could it penetrate? How much do you take off finishing a piece?
The fuel scoop was one of the first things I made from a spike.
Cindy Mathieu wrote:If you want to go vertical, consider bells. Also, heat rises, so its much easier to heat the second floor.
Our designs utilize clay chimney flue liners rather than cob because we are using bells and chimney flue liners are designed to support their own weight. In order to create a cob shape of the same height, you would have to create an very large pile at the base. Clay chimney flue liners can't handle temperature changes greater than 50° per hour, so they have to be insulated by ceramic fiber blanket, dense fireclay bricks, or an inside layer of smaller flue liners.
If I build the battery of bricks and cob on one side of it, would the wall itself function as a thermal battery to radiate in the other room?
Of what is the wall made? Standard frame construction does not a good thermal battery make.
The blog in my signature has an article explaining the difference between bells & flues.
It looks to me like your 'vertical double bell' could grow into a wall. With the divider near the ceiling of the first floor it would help keep the heat downstairs. Sounds like a good solution to heating multiple rooms with radiant heat.
mike Splendid wrote:>Are you trying to heat living quarters or water?
A Small pool.
Yes I take your point about fighting physics. Perhaps the way to do this is to go up and then come down in another vermiculite board tunnel before entering the heat exchanger i Have built. ie no 55gal drum. contain the neat on the way back down... so wait, does that mean I could use a riser that is half as high?
What physics allows pushing the heat back down without penalty to (canceling out) the draw?
I'd build a rocket/barrel stove and heat the water on top of the barrel in an open container that could overflow into the pool. You don't have to use a big heavy container.
I still cannot vie that file. Can you post a .jpg?
>but rather use bells.
I understand. I guess I am not clear why the riser is vertical? I assume because hot air rises and we want that to cause draw, but if that were true then what about the downdraft designs?
So if we can go donw whay cant we go horizontally and let the hot ir rising in the chimney section cause the draw in the system?
So to go a lkittle further into the logic here, I am heating a 5gal propane tank filled with water (that is slowly circulating under slight pressure from a sump pump)
I DO NOT want 5 gals of hot water perched atop a 5 ft riser. That meas building a large superstructure to hold it al and it ends up looking butt ugly and makes me nervous. I want the propane tank CofG LOW. Really I want it sitting at the end of a horizontal tunnel and for it to be the base of a chimney that encloses it.
The next part is that while I could cut and grind for week and whip out the MIG, I want to do this in a few hours with some fire bricks on the ground. Simple. Easy. Love it! So Really I want a long tunnel that is part firebox and part "riser". My idea is to run a number of smalled metal tubes into the "riser through the firebox to provide more air for the secondary burn. This will heat the air on the way through the firebox and its easy to lay some lengths of metal pipe at the base of the tunnel protruding out.
I am just not sure about the functioning of the "riser" portion of the tunnel.
What downdraft designs are you talking about? Rising heat is what powers a rocket stove, or any wood stove without a fan for combustion. Even long burn tunnels reduce draft, requiring a taller riser. Establishing draft with a long tunnel isn't easy.
Why do you think you need secondary air before you've done any testing? Excess air will just cool things off and require more 'makeup air' to be heated.
Extracting heat at the base of the chimney will also reduce draft. Extracting heat at the top of the heat riser helps the gasses flow downward.
ronald bush wrote:thanks ill check out your suggestion. it still seems to me that 6 sticks burning would give off more heat than 4 sticks burning. but thats why i ask questions, to learn from those that know.
Consider that it takes more air to burn 6 sticks than 4, and that the air has to be heated. Temperature produced will depend largely on air/fuel ratio, but BTUs are dependent on volume.
Are you looking for internal temperature or BTU output?
O.K. Now that I have your attention, this is really about how to apply caulk to seal a bathtub base to the Bathtub/shower surround !
First you fill the bathtub, then you climb in! Depending on your own and other peoples sensibilities depends on whether you you undress
First !!! In any case I still recommend warm water ! It reduces personal shrinkage !
The crack between the tub base will now be at its largest, and the floor and floor joists are deflected, any future live loading will be a small
fraction of the whole load .
Making sure the gap is clean and there are no lose particles you apply and smooth out the caulk, let cure 24 hours and drain the tub. From
now on the caulk itself is going to be under compression almost all off the time and when the tub is again filled it will return to its normal
shape and coverage !
Congratulations, this is another side of the same coin we were just looking at, and you now know how to FillCaulk a tub BIG AL !
This topic is officially hijacked and OFF- TOPIC A.L.
Unless you have a LOT of flywheel mass, you still have to vary tool pressure with pedal strokes on a treadle lathe. Look at the horsepower ratings on motorized lathes and figure what fraction of that you can provide with each stroke while balancing on one foot and manipulating the tool. Sharp tools are essential but make it trickier.
John Abacene wrote:...
Brancjing up from that, there might be potential for central home vacuum - start the fire raging, vaccum the floors, the dirt is instantly removed and incinerated. - No bags or filters to change!
Wood gas does not affect steel. I have built and used a gasifier forge, forging spikes into more useful (or at least artistic) stuff. I used Virginia pine (sappy, knotty) and can't see a better use for it.
I'd start with something like this (google "institutional rocket stove"):
Either use it as a 'double boiler' with pool water going through tubing coiled in water in the pot*, or as an open (no pressure) system with the pool water able to freely overflow into the pool. A large vat with multiple burners might be needed at your scale.
*Make sure the pot doesn't boil dry, maybe with a float valve controlled supply.
ronald bush wrote:i see talk of risers being too short. can a riser be too tall? when (if) and why does it hamper the performance?
also can the space in the barrel be really big? like 6" on all sides? if there is a lot of open barrel space does that mandate a larger pipe in the mass? as to not choke it down after opening it up in the barrel.
can the riser be offset inside the barrel, with no ill affects?
wow, learning about these stoves is an addiction! lol
In the PDF: www.aprovecho.org/lab/rad/rl/stove-design/doc/18/raw they discuss a heater with a tall internal chimney and how they prevent the fire 'being pulled off the fuel'. I'd have to see it myself.
In, "...flue transition area...",... are you referring to the 'C' or 'D' cross-section ?
The cross-section of the space outside the barrel which bring the gases to the 'D' opening is, as shown in the picture above, equal to 47sqin, which is more that twice the surface area of each of the other cross-sections... I cannot find any 12sqin cross-sections anywhere... can you tell me exactly where you can see that ?
About "laminar flow restriction"... you mean adding surfaces to generate turbulence ?
For your heat riser recommendation not to made it out of metal, i did hesitate between metal and a refractory cylinder... I will change the model to your recommendation. (Metal would get deformed ?)
Thanks and let me know where exactly you spotted 12sqin cross-section.
Satamax Antone wrote:Hi Ted,
Well, the first thing which comes to mind, your barrel to flue transition area is way too small. Even more regarding your barrel side gap which seems in the range of 11/16. Your flue transition hole has a perimeter of 18inches or thereabouts, X 11/16 that's a surface area of about 12 sqin. Too small compared to the 20sqin or thereabouts system size. Plus, the bottom of that transition area hole doesn't do much. And furthermore, you haven't accounted for laminar flow restrictions.
So, make your flue transition about 40 sqin, low and wide. Increase your barrel side gap to 1"1/2 or 2"
And please, don't use metal for the heat riser.
J.D. Ray, i think it's solidworks, as stated in the first post
At the transition from barrel to flue (shown in C) the insulation around the riser blocks all but a circle at the edge of the pipe. 11/16 (the gap) times the circumference of the pipe is all the flow area available. If you make the transition wider it will help promote flow down the other side of the barrel.
Thanks for the welcome and information. I will be looking at all of that. The unit I have designed is very proprietary, sorry but I won't be providing any information on how it works. My plan is to have any major servicing paid for in advance and for the product to have a 40 year warranty, but be designed to operate for more than 70 years. This is a critical aspect of a unit that is designed to enable reliable off the grid living. The owner/operator would need to do minor maintenance which would be dumping ash that collects in a bucket, cleaning fire tubes out once a month and cleaning air filters once every six months. Other than that the unit would require no maintenance. It would provide the things I already posted. The gas would be "wood gas" and would be stored in a conventional way under low pressure. It should be noted that using wood gas for cooking is more dangerous than using methane (aka natural gas), or biogas and precautions would have to be taken, most notably carbon monoxide detectors and ventilation during cooking. Also the unit is extremely different than other units on the market. It is a pure gassifier with new gas cleanup technology. It also enables the production of biochar if wanted for soil amendments among other things. Another benefit is that the unit is capable for running for weeks at a time without any additional fuel input. So if someone was sick or left for a few weeks it would provide everything they needed without any work. The unit could be integrated with solar hot water and other electricity generation as well as well systems integration. The idea setup would integrate all these systems and be custom engineered for the home size, climate, etc. This unit is designed for climates like alaska, canada, etc. It would not be competitive in sunny climates where there is little heat demand and where heat demand can be met primarily with solar hot water and passive solar.
Please let me know how much you think something like this would be worth.
Thanks for your time.
A 40 year service contract on an unusual and expensive/critical product, from a small company?? Not this guy...
J.D. Ray wrote:I've been trying to reign in my ADD enough to do a thorough body of research on rocket stoves lately, with the intent of building an experimental version in the next couple of weeks. Next month, I'll have the resources to buy some instructional material (book, DVDs, etc.), but I thought I'd take a shot at building one in the mean time to learn from my mistakes.
I've read several references to cross-sectional area of the burn tunnel versus that of the heat riser. Do I understand correctly that the burn tunnel cross section needs to be no larger than (and preferably smaller than) the cross section of the riser? This makes sense to me, given my understanding of actual rocket engine design (which is at best spotty).
If I'm using a 6" tube for the center of the heat riser, with a cross section of ~28 1/4", then the cross section of the burn tunnel should be less than that? Or no less than that? Exactly the same?
I think "rocket" refers to the sound, not the design. We're not going for thrust...
'The burn tunnel should be equal to or slightly smaller than the riser' is the general wisdom. I wouldn't sweat it too much.
bob golding wrote:i am cross posting this from the other forum. hope that is ok.
as i want to use the heater in my yurt i like the idea of having the feed outside as done by fishermans Daugher a few years ago. as i want to be able to cook on the top of the drum i don't want it too high. i can bury the burn chamber to some extent but was wondering about the ratios. if i keep the burn tunnel the same CSA as the 6inch riser but use a 8 inch riser would that allow me to have a longer burn tunnel with out increasing the height of the riser too much?
Not much experience to draw from, but since nobody else has answered I'll put my 2c in.
I think the CSA doesn't make much difference as long as it's not restrictive. A column of mercury under a vacuum will read the same atmospheric pressure no matter the diameter, and I think the same principle applies. Vertical distance and temperature will determine how strong the draw is.
Garry Hoddinott wrote:NO TRIANGLE??? Interesting design Bob. I know there are many UNCONVENTIONAL bicycles - but i had kinda figured some triangularity in the frame was important. Can you comment on the torsion forces and structural stability of this little baby? For sure the seat looks like a reproductive enhancement over the horn destroying horned seat. Actually it almost looks like a mobile birthing conveyance - haha
Zach explained it well, let me reinforce:
The frame is under compression from the chain tension. Along with some side-to-side force there is a net downward force at the bottom bracket - not much torsion. Pushing against the seat back/stays produces a bending force but the large diameter tube handles it well, whether steel, aluminum, titanium, or CF. I have examples of the first three.
Recumbents go back to the early 1900s but UCI (oops, said UCA in other post) outlawed them when a second class racer started whipping up on the big boys with one.
Fred Morgan wrote:If you have back issues, you might want to look at a recumbent. I have been a cyclist for years and I know a lot of my friends as they get older will try one, and then fall in love with them.
I don't have back problems but I started riding recumbents a few years ago for the efficiency and fell in love with the comfort. I wish I'd switched years ago. They're a little more aerodynamic than regular bikes and usually (except for high end ones) a bit heavier. This means you will go slower uphill and faster down, so they have wide gear ranges. And it takes getting used to not only the balance but a different set of muscles. When I get done riding, my legs may be sore but my butt isn't, and my hands haven't been numb. Not staring at the front wheel is an added bonus.
Once you're used to a recumbent they're not much different on the road than a regular bike. Other than the attention they draw... I've gotten dozens of 'cell phone salutes' - pictures taken. I ride "high racers" so I'm pretty much at eye level with drivers, but some ride "low racers" and tadpole trikes on roads.