Thanks, David and Arvid… We plan on beating it up good, and testing it with all kinds of variables… We’ll be testing temperatures with thermocouples, fuel sizes, fuel types (carbon from different species), and spectral analysis on the gas and exhaust – with and without steam.
Since this is open source, I don’t mind so much that people see some potentially poor design decisions… The more bright minds involved, the better it will be down the road. At this point, we still have yet to even flare this thing off yet… And nobody is going to want to become involved until we have a viable product…
My two biggest concerns are:
How much charcoal bits will flow down into the air nozzle (since it’s an updraft with an upward-facing nozzle) on shut down?
Will the ash flow into the ash bin without a shaker, and will small pieces of charcoal come with it?
Both problems are easily fixed because each of those components are detachable and small…
If #1 is a problem, we have 2 choices for a blan “B” with regards to nozzle plugging:
go with 3-5 smaller nozzles, pointing up at a 45 degree angle (inverted imbert nozzle arrangment).
same, but nozzles point down at a 45 degree angle (similar to an imbert).
If #2 is a problem, we can either try different sized perforated metal grates and/or try implementing a shaker system
First flare should be coming very soon… I’ll keep you guys posted.
Troy, on the colored rough diagram a few posts above you show a sealed water container. Does sealed mean it creates a small vacuum when the water goes out? It also shows lighter colored bubbles in the container. Are those steam bubbles that rise through the needle valve to pressurize the sealed container? Does the needle valve drip really slow so that the coil is mainly filled with steam and not water? Would 3 or 4 coils around do the same job or do you think you need the 7 or 8 shown? What advantage do you get by taking the gas out just above the reaction zone vs up higher in the hopper? I probably have more questions but this is enough for now. Thanks for this open source project!
There is a valve on top of the aluminum water tank (10 gallons), which will be left open when running the drip. No pressure. No vacuum. Please forgive my concept drawing for any confusion We control the drip rate with a simple valve. Ultimately, it the core isn’t hot enough for steam, it just drips out onto the group, harmlessly. If we get too much steam, we’ll look at bigger tubing size (i.e. less turns on the wrap), or just just less turns with the same tubing.
The idea, based largely on Koen’s work, is to find the “Goldielocks zone” where we get a good volume of steam for cracking, but not too much so it lowers our reaction zone temps… We need those very high, with or without steam. But even 10% H2 in a predominantly CO gas flow will act as kindlings for the much slower flame front of CO.
In short, we’d love to hit a 50/50 ratio of H2/CO – like Koen has done in the past, but even if it’s 20/80 we’ve increased ignition speed… 50/50 would be amazing, because we would be able to pull energy from water, which is essentially free.
The advantage of pulling the gas out above the core is pressure drop… We will be working with very small feedstock sizes in order to get massive surface area for the various reactions. Sizes will range from 5/8 - 1/16th of an inch. We can go bigger if necessary. We placed the breather tube high enough so that we’ll still get cooler gas, but low enough to avoid having to suck through another 20+ inches of small feedstock.
Troy after a really hot shutdown I get a slag plug in front of the nozzle. So far a simple steel rod rammed up through the plug pushes it as side, exposes fresh charcoal and shatters the pieces near the nozzle to give more surface area too. First few pieces fall out coverered in slagged ash, a few more pokes and the crumbs are charcoal again.
Carl, The Titanium “nozzles” are M15 threads, so the outside diameter is 0.59" or a little less than 5/8", right? What is the inner diameter where the air flows? (So… these are the bolts that hold the front sprocket and crank arms together.) On Gilmore’s Simple-Fire design, the nozzles were 1" pipe wrapped in a piece of stainless. KVL and Troy are specifiying a smaller nozzle size for the Open-Fire. I’m not sure if that is because TIG ceramic nozzles and KVL’s “found” nozzles are only available in smaller sizes, or if they want the higher air velocity. Gotta think on this… Ray
I’m not at all good with metric nomenclature. These might work for a very small version, or in multiples. I was drawn back to these TI models because Al D melted his SS nozzle shield at Marshall. A couple errors were involved, but SS will melt! Would you rate ceramic plasma cutter nozzles at about 2500F?
I think K.V. Looken and T. Martz may have a solution to the nozzle problems using the TIG lens. On my Miller Synchrowave 250 I use the pink shielding gas cups made from Aluminum Oxide which has a melting point of 2800 F. In my Simple-Fire I started out with 1" black iron water pipe, then wrapped it with a stainless shield, and it slowly burnt away, so I screwed in another one and continued. One day, I took one of our kitchen ceramic coffee cups, and slowly drilled a hole in the bottom of it, and put it over the nozzle assembly. The air came out the big end of the cup, where my inlet pipe was, and burnt the paint of my gasifier (by the inlet). Then I wrapped the 1" pipe with stainless, and wrapped that with ceramic wool insulation which was actually packed into the big end of the cup, so the air HAD to go out the hole in the bottom of the cup. Max “Gasman” suggested a dog house arrangement, where the air came out of the nozzles and travelled a bit to the charcoal, so the charcoal could not fall around the nozzle and “forge” it. This was my dog house. The glaze on the cup bubbled and fried. Then the cup cracked. (It is still cracked but is holding shape.) To replace my nozzle, I have to remove all the charcoal through the top of the unit. My plasma cutter is a Miller Spectrum 375, and I’ve never replaced anything. I has a hard black cup, and it is about an inch away from the tip (XT30C Torch). If you are asking about plasma plasma cutter nozzles, and they are pink then they could be aluminum oxide–2800 F. BTW, I took your advice about the Eastwood 135 MIG machine on sale, and I really like it, although it seems to use a lot of shielding gas. (set at 25 cf/h, per the manual.) As K.V.Looken and Martz recommend, small charcoal is the key to running a charcoal unit. It took me a long time to catch on! (My Simple-Fire has the air inlet on the side, not the bottom.)
Since english is not my native language its sometimes difficult for me to express myself to give good explanations.
Using the smaller nozzle sizes comes from the old style gasifiers as the “kalle gasifier”
I use the small nozzles to “choke” the incoming air to a ratio income/output 0,6 to 1 ( theoretical starting point )
Balancing with airspeed and grain size of the charcoal completes the game.
Using the vertical nozzle in my case , had to do with to little space but it turned out to be a good position for obtaining good quality gas.
Since the goal of the gasifier is to make gas from, in our case, charcoal, i try to use as much knowledge available as possible.
The amount of air intake at the nozzle is smaller then the amount of gas exiting the gasifier.
Giving that air velocity and a “blowtorch” shape , is gaining more control in the process of gasifying the charcoal.
By focussing the air on a single point and a certain length, the reduction zone is getting more defined hence better controlled and the gas quality is optimized. ( the temperature at the focus point is doing the work )
Controlling the temperature that way, decreases the heat losses and the air escaping-bypassing in the charcoal, and gives a utmost complete reduction.
Using the ancient knowledge in different configurations, observe, learn and share…
This weekend i will work on the explanatory with some tables and graphics
Last night, we tried something new… We used a common wood chipper to make our feedstock, and attempted to pyrolyze it. Long story short… Success!
We knew that because the wood chips are extremely small and flaky (compared to branches, twigs, and split hardwood) – and that a pile of wood chips acts as its own insulation – that the very center of our double barrel retort would have un-pyrolyzed chips. So, we added a 4-inch pipe to the very center, welded it to the 30-inch inside barrel, drilled some holes on the inside pipe as well… Now, any chip would never be more than 7 inches away from a very hot metal surface… We also insulated it, added a very tall chimney… etc.
Here is what we didn’t expect… The whole process took 1.5 hours to complete. In the past, it would routinely take ~4 hours. How the heck did this happen? The massive surface area of chipped wood released an incredible amount of wood gas at about the same time… The retort was literally glowing hot. In reflection, It is obvious to me now that bigger chunkier wood & branches take much longer because the wood gas has to work it’s way out of the center of the wood.
I’m also not saying that faster is better… In fact, a lot of BTU’s went out the top as a blow torch when this thing was at peak (see image). Maybe we need to drill smaller holes, to regulate the woog gas flow, and to utilize some of that heat???
Another surprise was that we expected 50-60% volume losses… Our finished charcoal was still 2/3 full. Although we lost space by using a center tube, I kind of feel like we ended up with the same amount of finished charcoal… And we don’t have to grind it! It was perfectly sized… 5/8" - 1/16" … very little powder (maybe 5-8% will fall through he 1/16th" sieve. No dust!!!
We are going to make some minor adjustments, and see if we can regulate the heat a little more… because it was insanely hot!
In the future, when we productize a custom retort, we’ll make use of the extra heat, so I at least have ground to stand on regarding the BTU debate with the biomass guys
I forgot to mention that when the wood gas began to be released, the massive flare/heat lasted for about 30 mins. And this was WITH afterburners slits at the top of the outside barrel… I’ve never witnessed such a release of energy before in a double barrel retort… Amazing.
Of course, this was done in Riverside, CA, and I’m in Puerto Vallarta… So I didn’t get to “feel” the heat like Jared did… but I watched it live on his cell phone, and could distinctly hear him crying about the heat
Hi Troy, nice job!
I am trying to charcoal wood chips right now as we speak. I was questioning whether it will work. I guess I’ll find out in a couple of hours if my method works. Your set up is very neat and clean. Here is my set up.
I’ve checked it a few times now and not too optimistic. This is related to your above comment regarding the insulating factor. The diameter of the pail with the wood chips is about 12".
Nice looking retort troy. I also feel that it is important to recycle that heat. I have been using chunks myself feeling that the energy needed to chip charcoal chunks is less then that needed to chip wood. The retort looks like what hookeway? Was proposing. Am I right that you are heating inside and outside? Do you have one of your great drawings of the retort?
Best regards, David Baillie
Similar to the Hookeway, but it’s not a rocket stove. It’s just a center tub with small holes drilled on the inside (just like what is typically done on the outside of the inner barrel). Also the whole inner barrel is slightly raised (2 inches) above the ground level – which is the bottom of the outer barrel. I think that gap helps homogenize the burn temps in and out…
The whole key here, in my opinion, is to negate the insulation effect of wood chips, which can’t be understated… We had a big FAIL the night before the success… And to make it even better, we are going to add more insulation, and weld some “fins” onto the inner tube. The fins will penetrate into the wood chips, and act as another heated surface for pyrolysis. And the fins take up no space!
I’m finding that surface area is key to so many things lately…
David, I’m leaving on vacation early in the morning (6 days), but I’ll draw a diagram when I get back… Thanks!
I just wanted to report that we had a second successful burn tonight, validating what we experienced the other day. We even tried a different species of wood… Results are 100% charcoal with zero dust. It’s perfect sizing for our gasifier. The largest pieces are about 1/2" and the smallest are about 1/10th". (we did throw a few bigger pieces on top, just to see what happened, so if you see a few 3-inchers, that was that was.
We think that the sawdust-like and small particles that came with the chipped wood just vaporized with the intense heat. We started with 24 gallons of wood chips and finished with ~18 gallons. There was only a 1/4th reduction in the height of the feed inside the barrel. For us, this is a no-brainer… No sifting, no sorting, no grinding, no dust… FAST.
We’re going to put those extra BTU’s to work soon by making a green feedstock dryer, by wrapping an aluminum coil on the inside of the chimney, routed to a car radiator (laying flat) that sits under another 55 gallon barrel (upside down). The bottom of the barrel (now on the top) will have a 3" hole and a bilge blower to suck the hot air through. It should work pretty good. That radiator will be piping hot, and all that heat will drive any water out of the newly chipped green wood.
Guys, it’s all about having a hot surface a few inches away from any single piece of wood. You eliminate the insulation effect of chipped wood. Even though chipped wood is tightly packed when compared to branches and twigs, there are plenty of pathways for gas (and steam) to escape.
If you buy into Koen’s recommendations of smaller feed sizes (more charcoal surface area = more reduction), then this is a PERFECT method. We’ll shared diagrams and instructions soon… Or try your own!
We control the drip rate with a simple valve. Ultimately, it the core isn’t hot enough for steam, it just drips out onto the group, harmlessly. If we get too much steam, we’ll look at bigger tubing size (i.e. less turns on the wrap), or just just less turns with the same tubing.
