Josh Vaughan

Yes, keeping as much grease from the sink/septic is important. Here in Uruguay it is customary to install grease traps on the kitchen waste line. Once one maintains such a device, they will always minimize grease down the drain. Used paper towels have a second life wiping grease from pans before washing and a third life starting wood stove fires with their greasiness.

I would imagine that fresh ash from hardwood mixed with hot water and a bit of detergent and allowed to soak, would do the trick. The ash and water will make a weak lye solution to saponify the fat.

Perhaps the alkaline nature (saponification) of fresh wood ash mixed with hot water and a drop of detergent would work after a long soak.

Mike, This is a vid that i made about the barrel pyrolytic converter. It is in Spanish, and I hope that you can understand the ideas,

Hi Mike,
I started making biochar with an oil drum cut open like a butterfly to facilitate introduction of brush while precluding excess oxygen (pyrolysis).  There are a few small, (sand covered) holes in the bottom so that quench water can drain but oxygen cannot enter during pyrolysis. Realizing/enduring the heat produced by the hour long production of biochar, I thought, "There must be a use for this obnoxious, face searing heat!" And so I set the barrel into a trench beneath an enameled steel tub. The shallow end of the tub is over a dug out flue that goes to a barrel modified as a chimney. This provides the draw for the flame. This is a prototype and rains have caused problems with the fill in which it is dug. Translation: Extremely happy with proof of concept, however I need to build proper masonry retaining wall for the surrounding earth.
While it is an ecological honour to make biochar, it is absolutely sublime to rest ones weary body in a hot soak.
Josh

DIY: Stove black. Grind some charcoal very finely and mix with equal portion of graphite lubricant powder. Mix this in with an oil binder, we use bacon fat because it smells good as thew stove heats up for the first time after treatment. I use the end of a small piece of 2x4 wood to rub it into the surface. I do it hot sometimes too. It needs be done at least once a year, more is better.
On the subject of water flow through the coils, more is better. Yes the output seems cooler but the beast heat transfer happens when there is the highest temperature differential. This allows for maximum extraction of heat from the flue.

Another, DIRECT FIRED, method that I have been very happy with is my Biochar Kannibal-kooker.
https://www.edhat.com/news/biochar-and-the-kannibal-kooker
It takes a bit over an hour of feeding to get hot and provides a nice hot soak after working to make 5-10 gallons of biochar. Obviously the fire is completely quenched, to save the biochar (ash no bueno), BEFORE getting into the tub. WARNING: While firing, the metal tub surfaces are dangerously hot, especially above the waterline.