Hey BillS.
Man I’ve already said enough above for any three people. Not much more I can add that would not further confuse. Now off of my started topic on to your own personal project topic I’ve even been going back up and editing out to shorten, and hopefully clarfy.
Regards
Steve Unruh
First off Steve, I want to thank you for all the understanding you have given me so far.
Secondly, I need to be honest about what I am confused about.
1). The difference between the Imbert versus the WK other than the utilizing the gas heat to warm up the incoming air.
2). Hour glass shape versus a flat plate restriction. I like the flat plate because how I understand it, I can alter the diameter to the size I need for a different size motor, or just for getting the correct diameter for my 12hp Honda. I also like the flat plate because I feel I will have an easier time utilizing the reduction zone to preheat the incoming air.
3). What needs to be insulated? The fuel in the hopper?
4). Restriction size. When I first posted my unit, I was with the understanding by Steve U. that the 4 inch should work. It was also the suggested size by FEMA. It also made my ICE run.
When I decided to redo the hearth, I received the ‘Imbert Nozzle and Hearth Diameters’ sheet. Basing the CFM on 24.4 for the Honda, my calculations came up with a 3" diameter.
Now I have two proven builders/operators suggesting a 2" diameter restriction
5). If I go by that sheet, it suggested a length for the reduction zone. It shows the reduction zone flaring out which allows more coals than a straight tube. If I opt to go straight, do I allow more length to make up for the lost volume?
This it for now, it will get me started for my design. Any input would be appreciated.
Bill Schiller
Im getting in here a little late but if you run with a tighter restriction this may cause a reduction in flow. However, keep in mind this will also cause you to get into higher temperatures. Higher temperature will yield more H2 and as long as the materials you build out of can take it this is a better way to go. Even though volume is restricted the higher H2 will more than make up for the loss in flow and produce cleaner gas.
Your reduction should be designed around your fuel density. From my experience the reduction depth layed out in the “Hand Book” is good for most chipped or chunked fuels. However, I have to shorten this up for smaller denser fuels to prevent grate clogging. In my experience a straight tube will work but in a smaller system it may be prone to clogging or inconsistent fuel flow depending on fuels used. If you use this to create a short throat and then open this back up to create a wider but short reduction it will flow better. You want your char bed to be as HOT as possible and as large as possible.with the longest dwell time as you can with out restriction flow. The better you can do this the more chances the gases will have to shed the oxygen. The way I understand this is that whats happening above the restriction and below it are two different things. Above you are simplifying and below you are dismantling. So above your restriction you want to break down the fuels into there simplest chains. The better you do this here, the more chances and the easier it will be to reduce these chains bellow.
Thanks Matt. So when I read about having a char bed before the start up, is a person filling up the reduction under the restriction with char and then filling it with fuel? Also I could or should have up to a 6-8" diameter reduction zone even for a 2-4" restriction or choke plate? I imagine it is possible for the reduction to be too big? As I type this I believe it is possible for it to be too big because that space would need to constantly have char in it in order for the reaction to take place. So if one is ‘overpulling’, it is possible to change up the fuel density or the size of the fuel to maybe alleviate that a little?
Ok Matt that all makes sense. I really appreciate this info.
Bill Schiller
Pepe and Arvid,
Thank you for those diagrams. I will study them and see how they compare and see what I can/should implement.
Bill Schiller
I found air leaks by sealing off any openings and using a LITTLE compressed air to pressurize it and going over welds with a paint brush and water/detergent mix.
i know with our little unit, with an eight hp briggs is almost not being pulled on hard enough. i suspect a sixteen wouldn’t be to much for it.
what is the displacement of your honda?
Hi Bill,
The first time you light a virgin gasifier yes you will need to fill the reduction zone of the gasifier with char. It will not work without this, and you will need to establish this before the machine will work. After you have this established and built up you should not need to do this again. You never want to run your machines fuel below 4" above your jets.
The size of your reduction zone does have some limitations and will depend on a few things. Like I mentioned above your reduction zone needs to very hot to work most efficient. The hotter the more H2O to H2 that will be converted and also the lesser the chance of it recombining. However, the bigger this is the more work it will take to keep it hot. So if it is to big it can get too cool and things can then go the other way and the machine will crash. So yes you can make the char bed to big.
As for the fuel density question this is exactly what you should do. Changing fuels will tell whats happening and what direction to take if you need to make changes.
Arvid,
The displacement of the GX390 is 389 cm3.
Thank Matt,
So apparently some things are starting to make sense with me. But when you say it “needs to be very hot”, I imagine this is controlled by having the restriction, reduction zone and air jets fine tuned to the ICE?
Bill Schiller
Correct, core temps should be above 1400F and to get into the higher H2 yields you need to be around 2000 F. The hotter the better but then you are getting close to melt down mode. 1800F is a decent temp to create engine quality gas with out sacrificing the longevity of the machine. But if your reduction, restriction and jets can take higher temps then you can crank it up. Our gen 4 machines are averaging well over 2000 F with out any damage to the machine. We now use a very heavy duty cast stainless steel reduction cone. The gen 5 machines need lab testing yet, but I am hoping they will average 2400*F or higher without damage.
based on 389 cc and 3600 rpm using standard imbert math you’d get 4.033 L/s or 8.546 cfm. that would put you in the 1" restriction range… I’d never build anything smaller than 2" hense my previous recommendation.
I run softwood chips in a unit with a restriction that size with out any real problems. I use a 8 hp briggs.
Thanks Arvid. Can you tell me where I can find ‘the math’ applicable to engine CFM? If that’s the case, I need to change all the other dimensions as well.
I’ve been scratching my head how Wayne adjusts his restriction. The best I can tell, his restriction is at the bottom of the fire tube? I watched the video a few times and that’s what I can tell. Is that the difference between An Imbert and a WK?
In this picture I have not included the air jets which will be mounted on top of the brake drum. I was thinking of welding a 8" sleeve to the bottom of the reduction zone to insulate. Question: can air be the insulation? Or would it be preferable to use a material such as this?
High Temperature Heat Flame Resistant SilicaXT Insulation Batt
Take care,
Bill Schiller
http://jamclasses.drbanjo.com/static/dimages/Drawing.jpg
Good Morning Bill,
I have to deal with mud, rain, cattle and miles ( the miles part will be fun, SWEM ) this morning . I was able to trap cattle yesterday and hauled most to the cattle sale but need to take five more this morning.
As soon as I can turn loose I will build a model of the burn tube and adjustable plates. I will take pictures and video and post in the builders section ( constriction #36 choke plates ) I should have it there by tonight.
BBB
from Dutch John’s site woodgas.nl
G = V x n x 0.5 x 0.48 x 0.72 [l/s]
60
G is the needed quantity of gas in liters per second
V is the engine displacement in liters
n is the rpm
0.5 is the four stroke factor
0.48 is the mixture composition (1: 1.1)
0.72 is the filling degree of the engine (assumption)
60 for the conversion to seconds
that finds out how many L/s you need. you can convert this to cfm… lots of places on line that do it for you.
DJ’s example G = 2.32 x 2,750 x 0.5 x 0.48 x 0.72 = 18.4 [liter cold gas per second]
60
d = square root from (4/pi x G/Vi)
d is the restriction diameter
pi is 3.142
G is quantity of cold gas per second
Vi is the superficial velocity being: 2.5 [m/s] = 25 [dm/s] for an Imbert
calculates the restriction after knowing the L/s requred.
DJ’s example d = square root from ((4/3,142) x (18,4/25)) = 0.97 [dm] = 97 [mm]
for simplicity I use Max’s math G = V (in L’s) x n (in 1000’s) x 3 to calculate L/s
5L engine at 2000 rpm would be
G= 5 x 2 x 3
G= 30 L/s… gets you in the ball park for designing… you would calculate the rest from that.
I made a correction in my last post . It should have read " construction video #36 , choke plates "
Thanks
Ok, I believe I have decided I’m going to build a mini WK as a stationary unit. I noticed there have been a couple of people on here that had mentioned they too were going to make an attempt. I was unable to find any follow up on how the units turned out. If anyone has info on some do’s and don’ts with a small version of a WK, I would appreciate any input. This will be for a GX390 Honda which is 11.7 hp.
It was suggested to me to go with a 12" diameter fire tube with a restricter. I on the other hand want to keep this as small as I can. I would like to keep this in a 16 gal. oil can if I am able. That may be a reach so I have a 30 gallon can available. I would like to be able to possibly run a 1000cc engine on it as well. So I decided to go with a 8" tube. and will try a 4" restricter for the 12 hp.
So if I proceed with an 8" pipe, any suggested lengths? 10, 12 or 14"? I was thinking 6- 1/4" air holes.
I really don’t want to reinvent the wheel, so if someone has better info, I will gratefully accept.
Bill Schiller
Hello Bill, Give me a call when you can 608-623-3000. This where I usually am during the day. I looked through the last year of yahoo mail and didn’t spot an e-mail there and also my local mail. I replied to your post a while back. I tried calling a 763-208-9–4 number and the voicemail is full. I will post best route on the Argos thread. Mike
This is what has taken up my time this past month and a half. There is so much snow atop of the buildings that the bottom layer melts a little even in all the sub zero weather we’ve been having. So the buildings with this style drainage will experience these ice formations and in return start leaking through the walls. On this building, it encased the electric meter and the gas meter. It was about -7°F with a wind chill of about -20°F and we use a hot pressure washer. When we’re done with a job, we have 1/4" of ice on us and completely soaked through all our layers. I am so ready for this winter to be over.
