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Scaling up ammo can gasifier to 30 gallon drum

I want to build a crossdraft/downdraft charcoal gasifier. I already have a simplefire but sometimes my charcoal isn't all the way cooked through and I heard a design like the ammo box gasifier can handle a little bit of uncharred wood better than an updraft. I want to be able to power a 400-500 cc generator for backup battery charging off grid on cloudy days. The ammo can build says not to go over 200cc, so I thought maybe I could scale it up to a 30 gallon drum. I already have this drum with a 1 inch flange 3 inches from the bottom from a previous simplefire project. I'm holding another close nipple to show where inlet nozzle might go. The mesh is to illustrate the grate.

A couple of questions

1. Do I need the side heat shields from the ammo can build? I figure there is now enough room for the charcoal to insulate the barrel walls... 2. I have a question mark in my drawing. How many inches between the grate and the nozzle should there be? What are the implications of too much space between the nozzle and grate and too little space? 3. Is a 4 inch nozzle ok?

Thanks,

Dave

4 comments

4 Comments

Thrivenrg

Sep 06

You want about 6 to 8 inches of char depth from the nozzle to the grate and build your grate so that it vents at the exhaust. Then build the boiler nozzle and it should work.

You want to create this so the air / gas flow can not migrate outside the reaction zone. So air in > creates synthisis gas > flow to vent in grate and then out the exhaust port. So because its round its a little more dificult to seal the chamber off.

Edited

Thrivenrg

Sep 06

Replying to

That is also esentually what you are already doing anyways. The DFX in charcoal mode had its guts removed. You are doing exactly that with this build you are creating right now.

If it were me I would build an exhaust chamber under the drum and leave the floor. Cut a hole at the back where you can install a grate that could be removed from the lower chamber. The CFX grate slides inside the ash chamber and I supply a scraper tool you use to drag out the char as it will pack over time. So all you do is install this drag out tool and slide the grate back and fourth and then drag out what is dropped. This helps keep the char bed loose so the machine can breath. You want a wide open hopper so it can flow and this is why charcoal machines run so much more stable. They are not subject to flow restrictions. That is what plagues the DFX even in charcoal mode its too restricted and is subject to bridging and fuel hange up.

The 2025 CFX RTR is the last design. The only thing I changed from the 24 model to the 25 model is the boiler nozzle and we will be making the water tank out of stainless along with a few other things that were prone to rusting. Other than those items the 25 model is exactly the same as the 2024 model. I cant make it any better its an awesome machine and it actually works.