Thanks Steve and Wallace for very good information. I have learned to turn it over with my hands, by turning the harmonic ballancer before starting, just to avoid rattlebones noise from old lifters. Think I’ll just continue the habbit to avoid bent valves when if I ever actually achieve woodgas.
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Today I did a little test of the exact blower recommended by Ben in the book.
I wanted to make sure I had the right suction of 9 inches of water column, as he recommended in the book.
Although the book says you need the blower to suck at least 9 inches of water column, I could only get about 7.15 inches.
There is a short video of the test on YouTube - https://youtu.be/u--tWBaWsrw
The specs from the pump manufacturer say the blower’s static pressure reaches a maximum of 2000 Pa at zero air flow, which is only 8.03 inches of water column. So it seems the blower recommended in the book doesn’t make enough suction to reach the minumum that Ben recommends.
Can anybody see any errors in my understanding?
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Hi Greg, my question is this. Why is it so important on the suction with this gasifier. Imbert, WK, and other gasifier designs do not have this mandatory suction requirements. A lot of builds use air mattress pumps. The only thing I see here is that your start up time for a flammable gas would be quicker.
Bob
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Nice looking blower. Expensive? Where do you buy it? Confusing that your vacuum sensor tube is connected to what is normally the outlet on other air pumps. I’m with Bob, on the amount of vacuum required.
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Hi Bob, I’m just going by what Ben wrote in the book. I’d like to ask him why the blower suction is so important, since it’s the engine that provides the suction and the blower is not even used after it gets going. Maybe this gasifier can’t even get going properly unless there is enough suction. It repeatedly says in the book that 9 inches of water column suction (negative pressure) is necessary.
Here are some excerpts from the book where Ben talks about blower suction:
Page 11: “. . . not having a good blower motor
with deep suction” causes gasifier to make tar."
Page 22: “Air Flow/ Suction Measurement-
In most common uses, airflow is measured in cubic feet per minute. But in a wood gasifier
we need very deep suction to pull air into a gasifier, through a bed of charcoal and
through a filter. This deep suction is measured in inches of water column, or the ability of
the suction to raise water by one inch in a vertical column. 9” of suction is the minimum
for engine grade gas. Your typical fan motor will not work because it doesn’t have deep
suction. The right suction source is critical. It needs to be a correctly sourced blower motor
for start-ups, then the engine can take over as a suction source after that.”
Page 31: 'Suction Blower-
The blower creates the vacuum needed for gas production. 9” of water column is the minimum."
Page 233: "3- Deep Suction-
Deep suction is what pulls air into the gasifier, across the hot charcoal bed and through the tubing. It’s
not about CFM. (volume) It’s about inches of water column. (suction)
9” is the bare minimum. Even more? Great!
The difference between a bad blower and good blower is like the difference between lightning bugs and
lightening in how your gasifier performs. A quality blower like the one recommended in this book is a
great start. If you are making gas for a medium sized or larger engine, then I would suggest getting two
blower motors to handle the additional gas flow needs. It’s always nice to have a backup.
Engine selection is another critical source of suction. . . . . . … "
Page 239: “Problem: Gas has tar.-
Solution: This usually comes down to bridging or weak suction from the blower. Use vibration
to combat bridging and use the specified blower (or two for big engine start-ups). . . . .”
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Ben is being overly specific, probably to cover himself. He uses the fan he recommends, that’s why he recommends it. As others have said, we don’t use anywhere close to 9" to start our gasifiers. 4-5" is usually fine.
Run it.
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I agree Chris, he is making sure you are way above the needed suction to make sure no tar is created.
Bob
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Yes when it comes to coving all of his bases as they say, Ben has done this, because it is necessary when you are selling a precise plans for building a gasifier.
One way to get a quick start up is add charcoal at start up before you add more wood. This give you more good quality gas and gives the gasifier time to warm up. Some of the other 75% we talk about on this forum.
Bob
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Hi Greg & all Mr Thicky here , having never used let alone seen such a posh looking instrument for measuring the suction on your fan would it not work slightly better if you were sucking rather than blowing ? i mean from my screen it looks like you have the pipe going into the blower outlet pipe rather than into the suction in the middle ,
Dave
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Good point!
Is the polarity reversed as well?
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@bsoutherland , @d100f , @Terry_Lavictoire - It cost me $310 for two of these blowers, including DHL shipping from China. They would have cost more each if I only bought one, so I have an extra, just in case. They came from http://www.sohon.cn/. Seems like I spent too much.
I didn’t think it would make any difference if I tested the pressure on the blowing or sucking side of the blower. So the first time I did put it on the blowing side, which isn’t completely realistic because it’s the sucking side that is connected to the gasifier. So now I have reversed the placement of the pressure detector, putting it on the sucking side. I was able to get a little higher pressure, 7.44 inches instead of 7.15.
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Thanks, Chris, for the big picture. It’s nice to know what others are using. I’m waiting a few days for a kiln thermocouple to arrive before running it, so I can monitor the hearth temperature and avoid melting it.
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Phew !! no one laughed at me ! lol only from what i know about fans is that they are designed to suck or blow and are not good at doing both , just make sure the direction is correct and maybe connect straight to the battery instead of through a pwm just in case its holding back some voltage /speed .
How did you get on with your charcoal retort , have you fired it up yet ?
Dave
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Well I can answer this from VictoryShop experiences.
It is mostly about just how LONG you want to wait until the system is sucked/or blow up to good gas making hot enough.
BenP sells/supplies mostly to guys who will be stationary and “experimenters” with different fuel(s) inputs for different expected gasifier outputs.
Meaning flare-guys. NOT engine guys.
So 9"'s was the average lowest found that would satisfy the flare-guys.
Engine guys like ChrisKY, WayneK, and others do not even flare. Just get the gasifer going just enough to engine run and let a LARGE engine run some and then let the large engine VOLUME flows suck the gasifier into good producing.
I am now converted to the Mike LaRosa, Tom Collins, Dutch John way of using a good-and-plenty all metal carpet vacuum powered by a cheap Chinese inverter and just sucking the gasifier/and/system HARD and quick to performance.
Much less early cool gas crap system coating then.
BenP’s recommendation was for those why wanted a direct 12vdc blower with variable speed.
GregC the stronger sucking AMETEX made-in-America ones were nearly $400. USD.
Since you have two of the Chinese ones you can series run these if you want a higher static pressure.
WayneK and other do this with 6-5-6 very low pressure marine bilge blowers. Ha! Ha! Check their electrical watts needed and you can do more with less, man. (Doesn’t matter - they only blower run for mere minutes! Not flare staring hours.)
There are no to the third decimal point, importance’s in any real applicable wood gasification. Just broad overlapping spheres of numerical possibilities. It is not two dimensional chess - computer predictive. Not three dimensional chess - computer intuitive. Woodgassing has a fourth dimension needed. Human determination to make it work.
The difference between a by-the-numbers food manufacturer to the masses. And really, really good true scratch cook.
When numbers predictability can play billiards, soccer, tennis, baseball all of the human challenge will be gone.
This is why I have consistently refused to play the woodgasing numbers games.
But do insist on real make-power applications. That is real. And comparable to other ways to make power.
Regards
tree-farmer Steve unruh
Parallel run them if you want more flow volume.
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Here is a 12 volt option for higher vacuum and a lower price ($42) :
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@d100f Dave, I tried it without the pwm and it was the same as the maximum with pwm.
Charcoal retort is finished. I might fire it up tomorrow or wait a few days for a kiln thermocouple I ordered so I can monitor the temperature inside it. I had some challenge making the insulated lid and I’m still not completely happy with it. There is also a 5 foot ‘chimney’ made out of furnace ducting which is not shown because the ceiling of my garage is too low. I plan to add fuel to the burn pipe through a 2" x 8" slot in the chimney. I’ll post updates to this topic.
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Bruce, are those brushed motors so that they can be speed controlled easily?
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Also do these have plastic body ? it only says black in the description , and does not ship to Australia
Sad Dave
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Yes, plastic body but good for engine compartment temps. Works good with a 40 amp PWM.
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Them things are junk, dont waste your money they will burn up in a heart beat.
The blower was one of the greatest challenges for me and why I build my own now. Its very important the motor is sealed from the wood gas. Two factors are heat and the acids getting into the copper wiring and bearings.
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