CMU instead of 55 gal. barrell on outside of heat riser?

Hi Everyone,
I am brand new to this forum/ this website in general. I am building a rocket stove here outdoors, and instead of heating a mass I am going to attempt to use it to create BioChar, I am basically building a retort on top of the rocket stove itself. I was wondering if you all think it is possible to use concrete masonry units on the outside of the heat risor instead of the 55 gallon drum? Since I am bulding this outside asthetics are not nearly as important to me. Also, I am still using perlite to insulate between the heat risor and the CMU's. I am just wondering how this might affect the draft. In this forum I have seen the functions of the drum basically "pulls" the heat out of the initially hot exhaust. So part of me believes that for my purposes the drum is less important. Let me know!
-Mike

Mike Daniel : Welcome to Permies.com, and a big welcome to the Rocket Stoves Mass Heaters Forum, your forum thread made an interesting read, I had to work out
what you wanted to do to write this up, we like people who think outside the box, that is where we do our best learning and get new ideas !

I had to think a little outside the box to get you your answer! No this will not work, the job of the barrel is to radiate off enough heat to cool the exhaust gases to the point that they
cool and fall, it is the combination of the rapid rise of and equally fast fall of the Hot exhaust gases that allows the Push me - Pull you miracle that allows theRocket Mass Heater to
Work !

The concrete will not allow the heat to be radiated off fast enough to allow this to continue to happen it will fail dramatically Creating smoke, and smoke back everywhere !

Concrete is a poor material to use, the heat would destroy it on the level of its chemical bonds and the Concrete will also fail mechanically as it expands and contracts it will crack!

Insulating the inside of the concrete will not work because that will also stop the heat radiation that must occur here !

With a more conventional build, you still will be pyrolyzing 60% of the wood turning it into greenhouse gases to get a remainder in charcoal, or if you run your R.M.H. to produce the
heat to pyrolyze a separate batch of wood into charcoal you will have in effect pyrolyzed the 1st batch, turned that charcoal into hot exhaust gases and then thrown away the heat
energy in 60% of the wood in your retort !

Good Luck ! Big Al !

Mike Daniel : I'm sorry I was called away and rather than lose what I had typed for posting, I shot off what I had and hoped to get back to you before this !

While you had an idea that has been chased down and proved unproductive by other fellow members, you were 'thinking outside the box' this is always respected here!

In order to help your line of thought and catch you up to other members who have already worked at this line of thought, let me point you at a couple of Threads here
in the Rocket Mass Heaters R.M.H.s Forum Threads !

Fellow member Bill Bianchi who was where you are now 4 months ago, He has reported on his research and builds in Two (2) long Threads 'waste to biochar via Rocket
stove' and 'Rocket Stove Gasifier' both pages !

Please consider going to Permies.com(s) Sister Site richsoil.com and click on/go to Rocket Stoves There you will find a series of videos built by or under the
direction of Rocket Mass Heater Pros. What you will see there can be 100% trusted, not like most of the Jreck on U-tube land !

Late note ! Whenever you are reading a page always look to the bottom of the page, at the 'Similar Threads' section, this is always a good place to check for information,
especially 'till you teach yourself how to do a Google search for material here in Permies A. L.

For the Good of the Crafts ! As always, your Comments and Questions are solicited and are Welcome! - Think like Fire! Flow Like Gas! Don't be the Marshmallow ! BIG AL

Allen,
I most certainly appreciate the input. I will take it into consideration, and actually I wanted to add that I planned on using waste heat from this kiln to heat an already existing greenhouse. With what you said though, I am actually considering putting the kiln inside of the greenhouse (I do have room for this). I did want to attach a rough sketch of the FRONT of what I had originally planned to do. Imagine this sketch begins on top of Ioanto Evans rocket stove design. So right where the insulation ends is where the top of the heat riser that will lead into a 55 gallon drum, and the smaller circle inside of that represents a 30 gallon barrel that will be used for the oxygen limited retort. The CMU’s are on the outside of that insulation. This is all somewhat to scale, I was thinking I could still use the CMU’s, but I would have to add just that much extra insulation, which I do not mind doing. Your input is appreciated. I have attached the file with my sketch, hopefully it goes through.
Thanks!
-Mike

Mike Daniel : To the man with a hammer, all problems are nails. There is a corollary I have noticed as It involved a neighbor, To the man with a dump truck all problems can
be solved with a load of fill ! I believe that you are telling us you have some experience with Cement Blocks, and wish to use them in your project !

I understand that you had put this sketch together before getting my answer, and you still hope to salvage some part of your original design to create a retort to bake your
wood up to the pyrolyzation step producing Charcoal/Bio-char.

There is also a separate group of Bio-Char enthusiasts you can find by Google-ing ' Yahoo Groups' and 'Bio-char ' the yahoo groups formate is a little confusing but should
allow you access to conversations with People like Bill Bianchi who re 'out there doing'! Please come back here and give us a report ! For the Good of the Craft !

As always, your comments questions are solicited and Welcome! Think like Fire !, Flo like Gas!, Don't be the Marshmallow ! PYRO-Logical big AL

Late note Edited in for inclusiveness, Dave There is a whole Parallel section on using a retort to 'gasify' Wood Gases through Pyrolyzation, you can follow it in the Bio-gas
Forum Thread ' Rocket Stove for gasifier or still ! Marcous B. is very knowledgeable on this subject ! A.L.