I am unfamiliar with that “water it down when done” step. Would you explain that?
Its fairly simple, when you go to restart your engine and engine is locked up and then you pull the valve cover to find bent push rods, broken rocker arm and a seized up intake valve. Thats is a really really good indication you made tar.
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Welcome Docblack to the site. If your gasifier is up to proper operating temps, there should be no tar getting into the cooling gas tubes. If you are speaking of the hopper cooling tubes they are vertical tubes and try not to have 90° bends going down into the holding condensation tanks. The drain should be 2" straight down from the bottom of the tank. Use a rubber cap to seal the drain and a screwclamp to hold it. The hopper is very warm when the gasifier is running and it takes hours to cool down. By this time the tars have run down into the holding tank. When I run my truck in very cold weather I drain the tar out of my tank. Some of the members have removable tar/water condensation tanks they can move in to a warm area. Mine is built into the truck so I dump while it is warm when it is going to be freezing weather.
This is for a wood gasifier, if it is a charcoal gasifier you should never have tar with good engine grade charcoal. If you mix wood/charcoal now it is possible to make tar. Many , many designs for gasifiers.
Bob
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Good to hear of more people here in MN interested in gasification! Welcome!!
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Matt, thanks! Is there any hope of avoiding this with a routine "shut the engine down after a gasoline/solvent (Seafoam?) running " step?
Is there a way to discern you are making tar when it is happening, before glueing an engine together? Does the flare gas look different? Running some gas over an ice bath? A white filter?
Thanks Bob! That does solve a question i had about WK hopper. Understanding the 25/75 % idea, and planning a stationary build, and seasonal use, wondering about a long loop to turn hot gas into Minnesota ambiant temperature gas. Would you guess that reaching 20 degrees Farenheit would assist in condensing out remaining tar? 10 degrees? Zero? Has anybody tried this?
Ending the run on gasoline is always a good idea. Maybe for a good 5 minutes.
If you go to start it the next day and the throttle is a little sticky, hard to move, it probably has tar. It would be a good idea to get some temperature probes, to determine if the gasifier is running too cold to convert the tars. Many put a probe at the grate, some at the exit gas on the gasifier body. I think the grate would be the most accurate.
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If your gasifier starts making tar pass the grate area or if it has no grate pass the bottom of the firetube, you can slow it down at the drop box, cyclone, cooling pipes even the filter. But you can not filter it out. If you are at a 1000 °f at the grate area the tars have been cracked. Up in the hot lobe area it is 2000 °f to 3000 °f. This area is just below the nozzle or nozzles on a down draft and above the nozzle or nozzles on a up draft unit.
So simply do not make it. If you do hopefully it is very little. The hay filter can catch some of it. But you have to change the hay out and put fresh hay in for a few runs each time.
A hot filter can catch some to. But again it will need to be cleaned.
If you think you made tar and ran it into your engine, switch it over to gasoline or diesel and run it for a while before shuting it down. You will need to do this every time until the tar as passed through the gasifier system or you have cleaned it out.
Bob
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How about putting some sort of white cloth screen between the gas metering valve and the carb. If you were making tar it would show up in the cloth. Also if you have a generator that you pull start or start with a drill then you can try and turn the crank over to see if things are locked up. I run on charcoal so tar is not an issue but my secondary fuel is propane. That would not clean anything up if ran through on shut down.
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Thanks, Tom! I was wondering if there was a visual, outside the engine, way to check for tar.
Hi Bob! Will you please elaborate on that “water it down when you are done” step? Is that just to wash off ash and cool charcoal once you have full container? How much water fo you use? How long is the drying afterwards? Thanks!
Okay Docblack, I use a old wheel barrel metal tub no frame or wheel on it. It even has holes in it from the old bolts rusting the tub out. Fill it with water laying on the ground. The hot coals are place into the water. Lots of steam ofcouse coming off it. After it cools in less then a minute, I can easly use my small metal leaf rake to get under the charcoal and lifed it and put in a wheel barrel. The ash and small fines stay in the water. I will clean it out when needed and refill with water. I then take this charcoal from my fire pit or retort and take out where I have my heavy dute plastic laying on the ground on a slope. On the bottom half I dump the charcoal out and spread it out the water drains out of the charcoal and travels down the slope and off the plastic. I can cover the charcoal with the top half so rain will not soak it when drying the Sun and wind does the drying. I can then rake it up and shovel it into my bags it is ready to use in my Down Draft Gasifier. It is not picky about fuel sizing. My up draft was on fuel size. The real big chunks it can chop it with a shovel, but it usally just falls apart. If I have any brands the shovel will not break it up and back to the fire it goes.
If it is winter time water freezing temps. I can just dump the hot charcoal into a air tight barrel seal it up and let it cool down cold. I like to leave it for two days. This charcoal now needs to be screened , I use 1/4" to 3/8" rabbit cage wire screening. I made a trommal out of 5 gallon buckets and wood. Run it though the ash and fines are removed. Black dusty and shower time by the time I am done bagging this up. Handling it wet is the best way to go.
One more way. Go ahead and do this water cooling down way in the freezing weather and haul it to the piling area on the plastic leave it in a pile. Forget it until spring let the snow pile on it. Then in the spring spead it out and let the sun and air dry it. Then bag it up. Make sure you dump the wheel barrel tub out in freezing weather. My fire pit and retort are next to a down hill slope that drains into a garden area. The Bio char area. My drying area is right next to my composting pile. Any fine that remains after bagging I shovel it on to the compost pile.
Bob
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