hi Carl,
To measure the difference between the 2 sides of the tube.
if the left goes down, the right goes up. measure the distance (vertical) of the 2 fluid levels
edit: Tom C beat me at it
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Here are the parts I plan to use for a gasifier nozzle to power a 200cc cargo trike in Rwanda. 15 mm tungsten carbide nozzle screws into a Stainless 3/4 -1 coupling. Street 45 degree connector. Cross fitting for EGR and H2O drip. Flexible shaft for nozzle clean-out. The reactor body is 10" ID X 36" insulated chimney pipe.
I figure the insulated reactor will need some extra cooling.
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I like the baseboard radiator/cooler setup. I think I have some pieces
around here to put to use. I’m thinking their efficiency will give my
future cooler a smaller foot print and height.
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Very nice Bruce. As an aside, inspired by your MG project’s hydronic baseboard cooling system, I’ve also started using these, specifically the clamp-on style.
What I’m using is similar to this product from Fabtek
which uses 3/4" pipe and dissipates a (potential) max of 591 BTU per linear foot. The 1-1/4" pipe version dissipates 1527 BTU/ft, even better (and less restrictive). Caveat: the price for this stuff seems to be increasing a lot lately.
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I plan on twisting a long strip of 1/16" X 1" copper to go inside inside the 1 1/4 pipe to create turbulence. I think the turbulence will give better heat exchange than a normal laminar flow.
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Okay, round two of pressure readings on the small orifice (11/32") Leitinger nozzle 
First off, I had a strange mis-match in my water levels, about 1/16" that would not go away no matter what I did. I am not sure how to explain that, so all measurements are +/- 1/16" I guess?
@bsoutherland: I did a test on the filter resistance, and found it to be quite small. Here is the initial reading, with the fan pulling just shy of 1.5" of water through the filter. I figured that would be a good value, as it is what I will be shooting for with the engine draw.
Next, I pulled off the wool sock filter, and removed the wool batting that fills my ammo can.
Overall, my filter is reducing the suction by about 1/8" of water column. I cleaned it out - it had a little dust in the sock - and ran it again at a lower draw and got the same results.
Next i fired up the engine and took some readings of it during idle and under load. At first it was drawing about 3" at idle, but after maybe 5 minutes of warm up, it had settled down to about 2 1/4".
When I connected the space heater, it pulled a little harder, rising up to about 2 3/4"
I am curious about the drop in pressure as the engine warms up, any thoughts on that?
Seems like the takeaway here is that I am indeed choking the engine- it draws 57mm at idle, and about 70mm while at its maximum load. I think I will try boring the nozzle out to 1/2" next, and repeat the pressure testing at idle and under load. I will also check and see if that will give me more power to work with.
I figure while I have it torn down, I will also add an EGR system, and maybe slap some cooling fins on the sides of the reactor.
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It will do that. Most residential hot water heaters have a ‘spinner’ in the center tube. I am trying to go one better and make my heat exchangers both spiral path and counter current. But not yet up and running.
Rindert
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Hi Carl,
Don’t change more then one setting at the time. Then you learn most of your gasifier.
Stick with modifying the nozzle size alone at first. Then ad egr and test again
observe every little step you make and the outcome from those.
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That is a good design philosophy - I was thinking of just welding a section of pipe to my nozzle while I had the whole thing torn down anyway, and then testing the actual EGR later.
What are your thoughts on cooling my reactor with fins? It gets up to about 400F when running, which should not pose a problem for any of the materials, but just seems too hot to me. I suppose for a stationary application it doesnt really pose a fire risk or anything, and I could always put a cowling around it to keep fingers safe. I guess I will hold off on modifying it for now, and see if the change in nozzle, or EGR can eventually bring that temp down on its own.
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if you can keep the heat inside the reactor , not pulling the heat ou by the walls, the gas gets better… and less Co2 in the gas
a nozzle protruding a bit further inside, a nice balance in corn size charcoal… fine and coarse mixed well…
Works a a charm…
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In post 184 the picture shows the tie strap holding on leg to be putting a crimp in the tube— possible causing this discrepancy
I know the amount of time the vacuum runs high on start up, seems rather long, but every engine has to warm up the oil, and bearings, etc. During this time the governor is trying to hold a certain RPM. During this time there are drags on the engine that slow it down. To keep the RPMs up the governor opens the butterfly in the carburetor. The butterfly restricts the vacuum that is pulled on the venture of the carburetor. So as the butterfly is opened by the governor, more vacuum is pulled on your manometer. More simply, if you open the butterfly all the way, you are removing the restriction that it causes and you are directly reading the vacuum pulled by the piston. ( I think ) TomC
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Could it be that the liquid in both ends of the transparent pipe does not have the same density? The dye would not have been diluted homogeneously?
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I thought that too, and I squeezed the crimp out with pliers, and it still was off. I opened up the filter housing thinking that maybe there was a little residual pressure in the system - still nothing. I thought maybe the whole assembly was out of level, so it just looked wrong - but no, a spirit level confirms that the discrepency is real. @trigaux, a drop of dye seems unlikely to have changed the density (viscosity?) enough to cause it, but i am at a loss.
If I build another one of these, I might opt for larger ID than 1/4, as it seems to me that there must be some surface tension or friction related explaination. The bend in the bottom maybe being too constricted so that the water column doesnt have enough weight to force it all the way back down?
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Hi Carl , a quick fix for your size reactor would be as Koen mentioned would be to reduce the size of your feed stock down in size and or as a temporary measure wrap some insulation around the outside of your reactor to contain as much heat as you can .
Dave
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I have been mulling over this discussion about heat in the reactor, and went back and reread the whole original thread on nozzles to reacquaint myself with what has already been discussed. It dawned on me that I do not really have a very good “big picture” idea of what it is that we are actually shooting for in the reactor. It seems to me that I need to answer the following:
1: The ideal temperature in the lobe - With the heavy steel nozzle, or Dave’s tungsten carbide version, we seem to have overcome the difficulty of catastrophic oxidation or outright melting, so what temperature are we looking for to create the best gas? It we are creating fused clinkers that suggests that without EGR the lobe must be reaching around 1300 C, right?
2: Where is the heat actually going inside the reactor? We know we are limited to around 50C on the outlet gas, or else it becomes too dilute to run the engine, and our plastic hoses start to melt. I looked up the heat capacity for charcoal (.24 BTU/(Lb * F)) which its similar to clay or stone, about twice the value of steel. But, its density is quite low, maybe 2lb/gallon? Okay, going back to standard units here… I have ~8gallons of charcoal = 16lb, and assuming 60 F of acceptable temperature rise (120F max minus 60 degree ambient) If I am doing my math right
BTUS = (lbs * F)/.24 or BTUS = 4000.
In another thread, @k_vanlooken you said
So what I am arriving at is that gasifying 1lb of fuel should liberate enough heat to bring my hopper temp up 60F (assuming no outside losses, no loss to the steel parts, etc). That actually seems like it might be about right, once you figure in those other heat sinks. I am getting to that temp before I manage to burn more than a gallon. (of course all these values are quite sketchy)
I drew a couple of reactor diagrams to try and illustrate what I think you are talking about (please correct me if I am wrong).
Koen, you say
By this I imagined you meant something like figure 2 - fins on the reactor are dumping heat and thereby pulling down the reaction temperature all the way to the lobe?
In figure 3 I imagined a layer of insulation keeping the heat from escaping as Dave suggested, which would presumably raise the temperatures throughout the hopper.
So what I am wondering is; if the goal is to keep the heat in, is the only way to increase runtime to add more mass of charcoal? Could heat be bled out of the system higher up in the hopper where it wouldnt interfere with the reaction? Also, how does the size of the charcoal factor into this? Is it simply increasing the density by being more tightly packed? For that matter, could I store my engine grade charcoal in the freezer?
Lots of questions, but that just means there must be lots of answers
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bear with me for a week at least, until the bandages comes of, then i can type with my right hand again…
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Carl , my first attempt at a charcoal Simple fire was in a 25 liter container the same as yours i think , what i found was was that it would run a lawn mower engine no problem at all for nearly an hour or more before the whole thing got too hot , but once you put that engine to work and actually load down that engine then it changes quickly and maybe 15 mins worth of run time before mine got too hot .
I think for proof of concept the small reactor is worth having a play with to get your feet wet , but once confidence in your design is sorted then i think the whole system should be upgraded to a much larger version one that will have a run time of maybe 2 hours with no real change in temps .
This is my findings on my systems and may not be the same as others so take what i say with a pinch of salt , also no water or EGR and all charcoal around 5/16 up to just about 3/4 in size.
My 100lb propane tank with a horizontal nozzle would run my 7kva generator under load for a MAX time of 2 and a bit hours before it was starting to get hot up top , i would then get another 1.5 hours out of it before the top was too hot to touch and gas quality was bad enough to stop the engine , i would always have maybe about 10 inches of charcoal on top of the nozzle left .
My smaller portable gasifier was a little under 9 inches in dia and 30 inches high with a vertical nozzle in the bottom going in about 2 inches , this ran my small inverter generator for maybe an hour under about a 1.5 kw load before getting too hot to run anymore due to the hoses starting to collapse under the heat .
The largest simple fire i built was from a 220 litre drum with a vertical nozzle from the bottom and going upwards about 4 inches , this has the longest run time , but only just
what i have noticed is that from about 2 inches from the top full of normally graded charcoal this will also only run fully loaded for just over 4 hours before it starts getting very hot up top but by then the batteries that are charging off the generator are coming up to 80% DOC and so the current drops off and the generator isn’t working as hard and so will run for another 1.5 maybe before engine stops due to hot or no gas , again there is about 10 inches of charcoal left on top of the nozzle , if you look at the photo of the blue drum you can see a plastic label half way up the drum and the bottom half of the label has melted but not the top part , so thats as far as the real high heat travels on my drum .
I think the best sizes for charcoal and reactor would be as Koen says try and get charcoal around corn or thumb size and a reactor diameter of around 12 or 15 inches by about 4 or 5 ft tall would give a perfect run time of around 3 or 4 hours .
One day i will do some better pics and video’s of my running systems but this is just so you see what i am talking about , the small Gasifier i use a extra filter and cooler while running the larger one .
As its been in the 30’s and 40’s c the past couple of months i have not even been near to clean up the brambles and posom poo around it let alone be able to run it in this heat .
Dave
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Dave, Thanks for the pics and explanation. It is so helpful to have someone like you who is actually using this technology for real work and can give great advice.
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Thanks for the great runtime info, very interesting. I am really excited by the idea that the simplefire is starting to mature as a technology -especially on the topic of nozzles. Going back and reading the early posts there were so many unknowns, and a lot of good experiments have been done. Now, it seems like the basics are starting to be understood, and so the question becomes “what is the next thing that we make it better?” (dont worry Steve U, I did not say perfect 
).
There is a nagging feeling in my mind that there is a heat problem. Basically that too much fuel has to stay in the hopper just to keep the heat from escaping the lobe. I realize it will never be possible to run a charcoal hopper as dry as a gas tank, But it is a topic that I feel could be expanded on and studied. Perhaps this should be split into a new thread?
I was looking at your dimensions on the 55 gallon drum, and from the picture it looks like its about 36" tall. It sounds like you fill it to within 2" of the top, and have 4" of dead space at the bottom:
With the 10" left on top of the nozzle at the end of the run then, you have used about 55% of the volume of your fuel. That is heaps better than i suspect is possible with a smaller hopper (I did some math on my run today, and came up with a fuel consumption of only 19% before the temperature started to climb at the outlet) I realize that with a stationary application this is not really very important; it is at best a nuisance when you want to dig out the nozzle and clean out clinker and such. What I am curious about is if there are simple enough ways to better the fuel consumption percentage (and if anyone else thinks this is worth exploring ). Anyway, I will post some numbers from my tests when I get a chance to type them up.
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Carl , one thing i forgot to mention , and i guess its the same even for the smaller reactors , that on my large drum as fuel is used up it takes new fuel from the center outwards and so i end up with a very low level of charcoal spanning maybe 14 inches in dia from the centre above the nozzle and the outer dia of the drum stays pretty well high until you give the drum a good shake and get the charcoal to fall down and build up some more height , on my 100 lbs propane tank it does not seem to be as bad and so i am thinking a taller but smaller dia drum is really needed to get the longer run times , or a good shaking or bashing of the sides after a few hours will help the run time a bit better .
Dave
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