Chevrolet s10 4.3

General Discussion
#1480

I am not worried about making a fool out of myself, if I dont know something i fid out how it is and sometimes that is asking :slightly_smiling_face:

Is this also because of the free’d up oxygen from the h2o that reaction is further down in the charbed?

But this would depend on how wet the wet fuel is, there must be a turning point. Perhaps my thinking in the previous post was too extreme to the ends of the scale, i.e. very wet fuel.

This straightens out a questionmark or two in my head about hot systems :+1:
At work in one of the superheaters we cool the tubes with 500*c (930f) steam, I should have thought of that

Sorry Jan if I am cluttering your thread.

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#1481

Wood, chemicly, has theoreticly about ideal ratio of carbon to water. But air dry wood contains about 20% water and we have to deal with that. Most use condensing hoppers wich is fine but it adds complexity, space and the condensing part needs energy to operate. Energy that it steals from the hearth.
I preffer to add charcoal that among other benefits deals with those exess 20% water. Then, your hopper realy is just a container to hold fuel. No need to fuss with double walls etc an it stays cold.

Or, like Tone is experimenting, pre bake the wood. This gets rid of that moisture and actualy puts the carbon to water ratio in a deficit. Only downside is in this way we do not have the bonus of geting more fuel in the hopper like if we mix rocket fuel, as there are still voyds between the baked peaces.

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#1482

Facts and characteristics of wood gasification in a gasifier:
-completely dry wood would release a slight excess of water vapor in an ideal gasifier in addition to the strong calorific gas

  • because in all gasifiers there are quite large heat losses, for the processes to proceed, it is necessary to add fresh air, which burns part of the fuel so that the processes take place, thus H2O is produced in addition to CO and CO2 and we have an additional amount of water vapor, some people call this phenomenon " chemically bound water in wood"
  • the use of torrefied wood or a mixture of wood and charcoal thus represents an almost ideal fuel for a gasifier, but be careful, the ideal fuel at the nominal capacity of a “classic” gasifier, if the gas consumption is small, the ratio breaks down, excess water vapor is produced again, as heat losses the gasifier does not reduce gas consumption in direct proportion
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#1483

Haha, I’m way too slow :smile: While I struggeled composing a couple rows of text, Kristijan and Tone both managed to beat me to it. I considered deleting my part, but I’ll leave it as is


Could be - to some degree - but as long as oxygen is present any produced H2 and CO will burn. Not until we consumed all the oxygen the remaining useful gasses can be harvested. A self-regulating balancing act constantly takes place in the charbed - reactions shifting their locations depending on power demand, fuel size, moisture content, available heat - you name it. All we know for certain with a wood gasifier is that there’s always a shortage of heat and an excess of moisture do deal with. Batteling that fact is where diminishing returns come into play. Complexity vs simplicity and effort vs benefit - individual preferences.

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#1484

Why not put charcoal in anyway in between the voids, even moist charcoal however wrong that may seem going through the trouble of torrefying it with then the benefit to actually control the moisture content to get the best gas possible without producing steam which calls for a bigger cooler then or am I missing something?

@Tone does the torrefied wood not take in the air humidity while storing it to equalize the humidity or does it have to be stored air tight? Or is the cells of the wood changed/closed so no moist enters?

@JO_Olsson @Tone @KristijanL thank you, I am now up to half a percent of the 75

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#1485

Very well said JO .

:blush:

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#1486

How many of you have noticed this? You are driving down the road and you know by the miles you have driven you are getting low in your hopper. But you also notice you have more power and richer gases. It is usally the last fews miles and my hopper temp has risen alittle before my hopper temps starts to rise quickly showing it is time to reload the hopper with more wood.
Have you ever just pulled over and open your hopper up at this point. I have done this and noticed very little brownish smoke/steam will come out of my hopper. It has condensed the moisture out in my hopper. Looking inside all my work has been torified. Looks like what Jan is doing with his wood.
Now in my WK Gasifier, it has added heat in the begining by preheating the air. By using the exhaust system, then by heating it some more by the drop box heat exchanger. Then the hot air goes through the WK Firetube heating it more before going out the nozzles holes. Yes a more complex system to build. But all of it helps in torrifing of the wood in the bottom of the hopper and makes up for the energy lost by the condensing hopper tubes getting rid of the extra moisture. Yes, added weight to the vehicle. But it works.
So Jan is doing some steps here with torrifing the wood before it is put into the hopper.
This is what I see in my hopper at the end of the load before refueling it with more raw wood. Charcoal and torrified wood with very little moisture or steam coming out the hopper when opening it up.
I have stopped using really small charcoal in my hopper for my WK Gasifier, it makes my charbed to tight, It works better to use larger pieces. But this is my gasifier and they are all different in operations. Find whats works and go with it is what I say.
Good job on the over 70 mph Jan keep it up.
Bob

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#1487

I’ve thought about it Bob, but I don’t notice any improvement in the gas when you run out, just look at the temp in the hopper when the wood runs out.
I use firewood directly from the forest, dry spruce tre contains about 15% moisture.

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#1488

Because each gasifier reacts differently, and no 2 of us are running the exact same fuel, its hard to really say. Both of my trucks when running doug fir, pine, cherry, and maple when the hopper gets low it actually takes a few miles for the hopper to get hot and the power does not increase it runs exactly the same power level from i would guesstimate 3/4 hopper to empty. Within a 1/4 mile of the hopper temp just starting the rise there is a SHARP drop in power level, sometimes the power drops off within a few seconds of hopper temp climbing, and it is audibly heard in the exhaust note going from a aggressive pop if each cylinder to a muffled hollow thump. Though when running on oak the few times i have got my hands on it there is a rise in power in the bottom third of a hopper load in the toyota. I would like to try to replicate that with the dodge if i ever get my hands on cabinet scrap oak wood again

So is it the wood species? Is it the water content? Is it the gasifier design? Is it the restriction size? Is it it chunk size? Is it flow restrictions in gas lines leading to the engine? I think we could line up all our trucks and cars with our own wood or char fuel and have a race. Then pick a partner and swap fuel bags and run again the winner vs loser would change pretty drastically from the first race.

I have even experienced a change in power level from one hopper to the next, same wood species same water content, same batch of chunks relative to same size going into the same gasifier. Sometimes i refuel with rocket fuel and it seems the only difference is the hopper runs a few degrees hotter, but the power and distance traveled is the same. Other times there is a notable distance change

Now all of these notes of my personal experience are based on high speed high rpm pushing HARD. My right foot is stupid and always wants to hold the skinny pedal down and with the loss of power on wood not much of a chance of a speeding ticket i do it frequently as seen in my top speed testing videos.

To surmize my thoughts here, it is just foolish to look for gasoline power while on woodgas, its just not a direct comparison. The fast paced lifestyle many live is like a version of gasoline each day is like a bottle rocket shoot off at top speed and explode. Wake up and do it again. Woodgas is much more of a soft slow meandering creek, swaying its way through some quite woods.

Each system will operate different, there are just to many variables to expect repeatable performance

I do think this is one reason for charcoal as a fuel is under strict scrutiny of a dedicated hand making the fuel, it can be much more predictable fuel. Closer to a repeatable outcome like gasoline. Raw Wood in the hopper is like kerosene up to 113octane avaiation fuel. You dont know what your going to get, you just need the experience to know how to make the engine happy with the gas it is getting, and the gassifer happy enough to not pass tar

Jan, congratulations on your new speed record, congratulations even more on continuing to learn more how your truck, your system likes to run. Any day on wood is a good day

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#1489

Thanks Marcus !

You saved me a lot of typing :blush:

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#1490

Could it be too hot for the reduction?
I have read that the reduction in an updraft can be bad because it burns out the coal, also that it is not good that the wood is charred too early above the nozzles?

​Edit: Is there any difference in running with, for example, fir wood versus birch wood, if the moisture inside is the same?
Is the effect different?

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#1491

I dont quite understand what you mean exactly


Reduction can never be too hot, you are only limited by materials.

Every wood behaves diferently in my experiances. Just like in a wood stove. I never liked conifers
 they require a different gasifier, like Steve says. Power is good but they make a lot of soot and burn too fast.

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#1492

The charcoal in the reduction zone tend to “burn out” faster, or get blown to smaller pieces, when using fir, birch gives harder, more stabile char.
The other way, birch only gives harder charcoal, not so “porous” that reacts some slower (slower throttle response) i’ve always liked a mix of wood, mostly birch, the rest conifer.
But this is just my experiences, every gasifier works differently, and can be built to work better with different wood.
This got me thinking how a special " conifer gasifier" should be designed? To take in acount, lighther wood, more prone to bridging, tighter charbed (solved by Tone-nozzle) maybe completed with a grate agitator?

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#1493

Goran put it perfectly.

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#1494

Have you ever tried a hopper shaker of some kind for bridging problems?

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#1495

That’s a bit strange, I feel like I have a very porous carbon bed, now when I drive on spruce, it doesn’t become dense like when I drive birch and pine twigs.

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#1496

Very well said Goren.
For a conifer wood gasifer also make the lower area volumes a bit larger that the chart tables say. To accommodate the greater volume of the less dense soft char.
To minimize soots made - lower the flow velocities. Bigger volumes will make this so. Conifers are much lower ashing, so you’ll not need the speed-demon internal velocities to keep char surfaces blown clear and active. And those chart velocities will really burn up the soft super active conifer char too.
30-50% larger chunking helps too.
S.U.

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#1497

BobMac, yes hopper vibratory shaking when on conifer has been tried to prevent upper-mid system bridging. Only works kinnda sorta when the system is warm-hot and active.
But it will defiantly break down the lower soft char into dusting and flows clogging or being then swept on trough not doing it’s job.

Conifer anti-bridging is best done with a combination of adjustments. Irregular chunks forming. All-saw blocks will flats to flats stack. Have at least two sheared; variable angles cut sides.
Directed heat blasting upwards like done in the MENS with the added upper pointed air jets onto their “J” nozzles.
Put in added heat right at the tar ring level like is done on BenP’s book system. His “pyrolysis accelerator”
Slope direct the melted liquid tars to flow right down across the face of the air jets.

Active grate, yes. IMHO. But it must be a very gentle action without any upward swinging. That crushes soft conifer wood char.

If this all seems weird, just try re-developing for all of the really hard-to-do-cleanly, not-woods “bio-mass’s”.
Wheat and oats straws. Sugar cane bagasse. Old books and magazines. Corn cobs. Fir and pine cones. Bark chunks.
I’ll take wood. Any wood.
Steve unruh

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#1498

Hi Bob, no i have never tried that, had a lot of bridging problems on my volvo, building the rear suspension stiffer helped some, but i later rebuilt the gasifier itself.
The chevy i had almost no bridging problems, some when running chunked slabs from pine and fir, which i believe is mostly due to the “ragged edge” on the chunks, when i saw’ed chunks the problem was much less.
On another note: the volvo after rebuild really “swallowed” wood which lead to constantly tight charbed, which in turn lead to i built a electric grate shaker (windshield wiper motor, pushing the grate up and down) controlled from drivers seat, later automatically controlled, then abandoned because of better wood. :smiley:

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#1499

What can i say? I believe your gasifier just likes that wood better? Every homemade gasifier works differently, often problem solved by rebuild it, or change type/size of wood :smiley:

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