Thanks Ray & Jeff. Hopefully this conversation will help guys looking around for filter ideas.
Instead of a sock in the middle of the charcoal bucket, a 1 1/2" threaded spa filter (40 square feet of pleated paper) would work nicely. But, a 5" X 10" filter (40 square feet of pleated paper) is $30 from Spa Depot.
I have a 1" inline filter with a clear body and a fine screen removable cartridge. I wrap the cartridge with white fiberglass cloth so I can visually judge the effectiveness of different filters. I think Koen did a test with a white cloth over his flare outlet ?
Let me throw in my 2c.
As for charcoal gasifiers, by far, the towel sack filter worked best for me. Its self cleaning, works is moist enviroment (unlike paper) and extracts ~99%+ of soot. And, its cheap.
As for woodgas, things get tricky. I tryed everything from hay to scrubers, hot filters, wet filtrarion, sack filters… but nothing satisfyed me enough. Ofcorse, the best way to go is by reheating the gas and passing trugh a paperfilter like Max recomends, but that takes lots of space.
I did get limited sucsess with the sack filter thugh. The problem is gas moisture. I didnt extract hopper juices so all the water from wood ended rinsing the soot out of the sack material. Now l plan to extract hopper juices, will see if the gas is dry enough dor this to work.
Ray keeps digging up old stuff:grinning: I’ve tried a lot of different filters and different mediums but have placed them aside as too complex or overkill. in my mind, the cyclone is very important since it removes the heaviest dust. Since you are using high quality engine char, there is no tar issue so don’t even worry about that, Therefore, all you have to do is remove some fine dust that gets past the cyclone. Here are some photos of a filter I use on my smaller gasifier. The plastic bucket is 6 gallons and has a Gemma screw on lid. The filter is a standard water filter you can buy for a few bucks and comes in different micron sizes. It is a press fit into the 4" PVC pipe cap and easy to remove and wash. You can put a wool sock around it if you want additional filtering, You can also put a foam rubber disk at the bottom of the filter to catch any dust that comes in the filter inlet which is at the bottom of the bucket. Heck you can even dispense with the water filter and just fill the filter bucket with wood shavings or grass clippings. It is a pretty simple system that does not rust out. Just a tip of the hat to Jeff who gave me the idea of heating the area of the plastic bucket where the 1.5" PVC pipe goes through. This creates an air tight seal and is easy to do, Like him, I do not glue the fittings on the pipe either.
Gary in PA
Gary, your simple, clever designs have made gasification accessible far and wide. I love this!
I know you said, “the cyclone is very important,” but what if making a cyclone was a barrier for someone or you needed to throw a gasifier together in a hurry? How long do you guess your filter setup (sock over water filter cartridge) would go between clean-outs with wood shavings in the bottom and no cyclone on a 5 HP engine?
Hi bruce,
I agree with you, Gary’s idea’s are inspiring and indeed making gasification accessible for all. Thumbs up Gary…
Dough i “never” use a cyclone, making one , or at least something similar functional, only requires a elbow pipe on the place you insert in the bucket and let the gas stream swirl…
As i have some allergy against long maintenance intervals, i choose to refresh filters and charcoal before every run, with the exception of the “big” sets on the tuk tuk and Pickup, those where cleaned when there was need…
In case of dust, any settle chamber or swirl effect will improve the gas quality and or the maintenance intervals.
Your idea does sounds nice, keep us posted if its running…
Hi Koen,
In my experience, fresh loads of charcoal do start and run better than running on leftovers. Matching reactor and filter to the required load and duration for a daily clean out is a good idea.
I don’t have my new reactor and filter built yet. A friend gave me some 10" ID insulated stove pipe in stainless steel that I want to use for the reactor body.
It finally turned cold here, so my projects are slowing down.
Wow this is a question i was going to ask about just the other day but was too busy working on something to sit down and type about it ,and here you are now talking about it now .
I have like i guess most of us have a fairly large container for the charcoal so we get a decent length of run time , well last weekend i put together a 55 gallon drum simple fire for a friend , i have used a vertical 25mm tube into the centre of a ss dog dish and then covered it in refractory material , after a couple of days i did the first run , within 20 seconds …the time it took for me to get up off my knees and walk over to the flare tube with my gas torch i had one of the best roaring flares and another 1 min later it was attached to the larger of my inverter generators and running as good as anything , ran it for about 4 hours under a 2KW load and then shut down for the day .
Next run i opened up the lid and checked the level and topped back up to the top and relight the gasifier , but this time it took around 2 mins to get a flare going , and this flare was not the roaring flare of the first time , and the same with the 3rd time i ran it, and after every run i had refilled with fresh charcoal , i only ever had to top up the drum around 8 to 10 inches and so there was always a lot of the older charcoal left underneath , and every run since the first i notice that the gas is getting weaker, now it takes the generator maybe 10 mins to settle down to be able to put out over the 2KW mark .
I think Koens tall but fairly small dia tubes are a better way to go for smaller engines with a run time of about 1 hour and fresher charcoal with every refill , my smaller tank units run better than this big one i made ,once the charcoal is used .
Dave
Dave, Thierry,
Is there any other reason for a narrow vessel to perform better other than that a greater portion of the the fuel will be freshly added?
There is a tool used for aerating compost piles that consists of wings that fold against a shaft/handle for easy penetration into the pile. When the shaft/handle is pulled out, the wings flip out and tear apart the compacted compost. I’m wondering if this tool could be pushed down through the charcoal bed to touch the nozzle then pulled out. Perhaps this would supply some freshly broken charcoal surfaces for better startup? There is also a screw version. See both below.
I never used a large producer but keeping the reactor consistent was the idea behind separating the reactor char from the fuel magazine. No idea if this would solve the too big of a producer problem
This what I see going on here with the big hopper and not using a fresh load of charcoal on every start up. First most of these gasifier are pulling the gas up though the charcoal feed hopper and this is changing the charcoal, with fine ash dust and the charcoal is also absorbing other gases, that whats charcoal does, it is a sponge being so Prose in It’s structure. When everything cools down it is still there in the charcoal and it locks in. Contaminated charcoal is now what you have for your next start up and it gets worse as you continue to operate.
This is why I have decided to go a different route in my charcoal gasifier, side draft design on one and on my simple fire it will be down draft. Both will always have fresh charcoal feeding the nozzle and the reduction will be burned up into ashes. Also you will be able to run them on lower hopper levels before filling the hopper again.
I do not have the equipment to do the testing but I think my observation of what I have seen in what everyone has been experiencing is correct. If someone would like they could do a lab test on the charcoal before and after to see what is in the charcoal vs. the contaminated charcoal.
Bob
Dave, what you saw is a common phenomenom with charcoal. This effect is seen best by those who make their own charcoal for blackpowder. The wood type is important yes, but moreso, the temperature at wich the wood is retorted. If cooked too hot, black powder speed will fall.
The reason is, in contrairy to common belive,“fast”, reactive charcoal is not just pure carbon and mineral ash. I dont remember exactly but l think the rough molar ratio of formula is somewhere in the neighbourhood of C16H5O. Lots of hydrogen. Now, that is FRESH charcoal. Once it has been exposed to extreme heats and oxigen in the burning zone, all the hydrogen and oxigen evaporate, leaveing just pure carbon (chemicaly graphite) at cooldown. Graphite is much harder to ignite.
I saw a interasting chart once, showing ignition temp of charcoal cooked for longer times at lower times has a ignition temperature at about 350c. The high temp cooked charcoal ignites at 600c.
Thanks Kristijan for the explanations what is happening in the reduction or heat zone lobe area. Cleaning this area out before a start up would really help on the performance of the gasifier. The clean out box below my nozzle on my simple fire should work great in solving this problem that occurs in charcoal gasifiers.
Now I just have finish this gasifier project up, one of my no weld indoors winter jobs to do.
Bob
