Charcoal gasifier prototype for 5-7HP lawnmower engine

Small Engines Charcoal Gasification
#27

Well, I got everything put together today, and figured I would let the silicone gaskets cure overnight. Yeah right. I cleaned up the shop a little, tightened all the bolts, and then said, ‘screw it, lets fire this thing up.’

Here is a video. It was really easy to get a flare going with my little hand-cranked blower, what was not easy was figuring out the right number of turns on my valves to get the engine to actually turn over. In hindsight, I should have been a lot more systematic, but half an hour later I stumbled on a ratio that seems to work: 3.25 turns on the air, .75 on the throttle. And away it goes!

I have ordered a tach to help me dial in the idle, but I think I am going to need to make a few modifications first. With the engine pulling, my reactor thermocouple was registering over 2300F (1260C)! it is only rated for 800C, So I hope I didnt melt it. I might try moving it up higher to get it away from the hot core and I suppose I am also going to have to implement EGR. I also saw a puddle of water forming at the bottom of the hose coming from the reactor, at the filter inlet, so I might add a thin-walled cyclone onto the reactor to try and catch some of the water vapor.

Thanks for the input Steve, I have a couple of 12 volt 35AH SLA batteries that I can connect in series and hook up to it- that should work, right? I am going to mount a panel to the side of the generator for a multimeter, tach, and the kill switch for the engine.

And thanks everyone for the input, I will definitely check out that video about the cyclones.

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#28

I agree that a picture is worth a thousand words. That is why when I first read about cyclones working in a cylinder without cone shaped walls, I had to build one out of a clear lucite cylinder and run tests with charcoal dust. Seeing is believing!

Also, if you use a spiral air ramp, the tangential entry is not necessary. The inlet pipe can be cut off at an angle and entered straight into the side. The spiral air ramp creates the spin.

I have found this alternative geometry easier to build and very effective. There are actually two “cyclones” in this cylindrical arrangement. The central one that is cyclone shaped and the other which spirals down along the outer wall of the cylinder. The dust that descends along the outer wall comes to rest on the bottom and is then pulled in by the central cyclone and deposited in the collection chamber.

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Note that the larger diameter exit pipe slows the exiting air speed so fewer particles escape. The one inch exit mentioned above will work, but it is better to exit with 1 1/2 inch then reduce down to 1 inch.

Also note that this last picture was taken before the lid was installed.

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Small engine mobile fuel station
#29

I would like to see a cross section drawing of this Bruce. Very interesting.

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#30

I second Mr Don ! !

Marry Christmas !

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#31

I was thinking about the EGR this morning, and went back and looked for a picture I remember seeing (simple fire post 33):

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So, @glgilmore : I realize this is an old idea, but is it still sound? I notice there is no valve on the exhaust return line, either. Is that something that should have been implemented? My muffler not being threaded makes me think this is going to be the easiest way to keep things simple. What are your thoughts?

I hope everyone has been good this year, and you all get some charcoal in your stocking! Happy holidays to everyone on DOW!

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#32

Don & Jeff, Here is my current favorite small engine cyclone based on my research and clear cyclone experiments.

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Carl, yes you need a valve for EGR, but use a multi-turn gate valve instead of a ball valve for better control.

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Small engine mobile fuel station
#33

Oh, yeah, I use electrical lock nuts to fasten threaded pipes to the thin wall duct pipe and stove pipe plug lid. Seal everything with RTV. Notice in the photo above that I weld the 1 inch to the 1 1/2 for stability and alignment.

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#34

I like it. It is so simple of a design. Like the dust trap at the bottom. Thanks for sharing Bruce.
Merry Christmas to you and your Family.
Bob

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#35

Bruce, that is an excellent Christmas present you gave us ! ! I’m sold. I’ll add a sock filter on top.

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#36

Pruning has started up on the vineyard, so I have been trying to not spend all my time in the shop working on my generator project. The frame I built was starting to get covered in rust, so I slapped some paint on it, and now it looks pretty sharp. I got a free engine off a trashed old lawnmower that my brother had found somewhere - this one is a Honda OHC, and still has its carb.

I got it mounted to my generator frame today, and built an adapter to connect it up to my manifold. It was going to be a pain to implement a governor on that B&S flathead that I started with.

I also had been thinking about what people had said about using a drill to start an engine instead of the recoil start, but I did not want to damage the drill once the engine catches, so I put together a little 3/8" drive ratchet.

I cut the head off a crappy old ratchet that I got at goodwill, and then brazed on a short section of pipe with a piece off an old socket. You can buy something like this, but it cost like 40 bucks. I will probably put the pull rope back on at some point, as I feel like simple is best - but for testing this will no doubt save some frustration.

Next up is EGR, then I should be ready to do a few more start-up tests.

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#37

I have been looking for a ratchet, 3/8” drive to serve as a starter.

Voila… you built one!

Now why didn’t I think of that
Thanks

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#38

Bruce,
I like your vent pipe cyclone and using your ideas will try to build a totally no-weld version. Electrical lock nuts are the only type of pipe thread nuts available here locally, but I have found that black iron pipe lock nuts are better and have started to use them where I can. They do require a little more space, however. I have bought those and most of my other pipe fittings and nipples from supplyhouse.com. Thanks for the cyclone ideas. Also, I have seen high-temp aluminium tape and thought of adding that to the outside of the pipe seam in addition to filling the seam with high-temp RTV compound.

#39

Great overrunning clutch development OrCarl.
Two other that could be utilized would be an actual out of an vehicle engine starter starter/gear drive unit. Nippon Denso offset spur drive units have this as a self supporting unit.
10 speed bicycle rear wheel hubs have an overrunning unit in the gear cluster.
Regards
tree-farmer Steve unruh

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#40

Steve,
So that’s what they are called! I have bumped into those stronger pipe thread nuts, but didn’t know what they were called or where to find them. Definitely better for tightening and heat resistance. However, I have had no problems with steel electrical lock nuts and they usually have a curved shape which helps to conform somewhat to round vessels. Their tabs make them easier to tighten in tight spots using various punches, chisels, drivers, pliers, spanners, etc. where regular wrenches don’t fit. There are some electrical nuts that are cast from a softer alloy that don’t bear heat well. I use spiral duct that can be ordered from home depot’s online store. Comes in 5 feet lengths in various diameters. Strong, true round with solid seams and smooth interior.

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#41

Hi Carl, Looks like it is about ready to go! A suggestion is to move the air mixing valve closer to the carburator. Right now you need to remove about two feet or so of gas from the fuel line before the O2/chargas mixture gets into the engine. If it is too rich, you will need to add more O2 and it will take quite a few turns of the engine to see if that gas mixture is OK…or not. What I’m trying to say is by placing the O2 inlet closer to the carb, you will have quicker feed back on whether the O2/gas mixture is correct.
Make sense?
Gary in PA

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#42

Bruce,
Thanks for the additional photo. I may have to try the spiral pipe if I do a 6 inch cyclone.

#43

I got the electrical parts hooked up for my generator today, and finished up the EGR.

I welded on a stub of 1" tube to the muffler, cut slits in some flexible exhaust hose, and then clamped it on to the muffler tube with a hose clamp.

I drilled a bunch of holes for the exhaust to vent out, and the other end goes to a valve on the bottom of the reactor.

I got it up and running, and it really starts pretty well. Takes a minute or two of cranking to get the gas through all the lines - but it flared pretty much right away. I have been keeping the charcoal sealed up, so I think it has dried out now.

I put the pull starter back on, as the ratchet made bad noises - I think the jarring was bumping the latching mechanism over to reverse. Once I got a flare, it only took 2 pulls to get the engine to start. Gary: I get what you say about having better fine control with the air valve closer, but the response seems adequate, and I like not having the extra weight hanging on my carb. I ran it for 0.4 hours today, and played around a little bit with the valve settings. It seemed to rev up and down a bit every few minutes, and I would have to adjust the valves to keep it running smooth. Not sure what that means.

So, the engine seems to be more or less functional, the gasifier is working beautifully, but the alternator… well, all it does is turn. I was using a 1:1 pulley ratio, so it should have been spinning at about 2100-2500 rpm. I might try it again tomorrow with a larger pulley, and see if that fixes it.

This is the alternator I ordered. I am confused by the “Polarity: Negative” I think I may have hooked it up backwards! I saw a red insulator on the output stud and assumed that it must be positive - but the case is from a 12 volt alternator, they just swapped in a different regulator to make it function for 24 volts. I hope I didnt cook it.

Well, I will try reversing it tomorrow and see if that does it.

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#44

I installed a Underwood welder on my 1990 Bronco which has a 120 amp alternator.
It will not generate until the motor is blipped to about 3000 rpm.
After “energized” it remains generating even at 700 rpm idle speed.
I would try speeding it up before reversing polarity as that may hurt it.

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#45

Ditto what Michael said. The key words are: “one wire self energizing” it needs to turn faster until it energizes, your polarity is probably right. If you are lucky Steve is reading the thread and will chime in… also when the alternator is loading down the motor some of those engine blips should go away…

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#46

I will try it today with a bigger pulley and not reverse the hook-up polarity. I really wish the manufacturer had included some sort of spec sheet with this unit that would clearly indicate polarity, cut-in RPMs, etc. Well, I will give it a try and report back.

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