The Riche' Retort

Grimm · October 7, 2019, 3:41am

So, anyone who has made charcoal knows, there is a lot of wasted potential in the process. Especially if you’re making it by destructive distillation in a sealed retort, you’re probably thinking “there’s just gotta be a way to harness those gasses.”

There may be a way. The Riche’ Retort gasifier was developed about 120 years ago, and according to books about gasifiers from that time, seems to have been able to clean up the gasses from the destructive distillation process.

In a very small nutshell, it is a tall, relatively slender (10 inches or less) tube, with a portion near the bottom heated to cherry red. The charcoal in this portion would have been glowing hot. As gasses formed in the retort, they would have to pass through this zone of hot char on their way out, which should crack the tars and various other hydrocarbons into basic components, CO, CO2, H2, and some other light odds and ends.

I’m primarily starting this thread to share this “lost” bit of gasifier history. But also because I felt like I hijacked Koen’s thread about a tar cracking device.

I’m putting it in the charcoal section because even though the charcoal is technically a byproduct, I’m sure a lot of charcoal users will be interested in the information.

This thread is more about the original Riche’ Retort gasifiers, and any related science or theory behind it’s operation. I’m in no way shape or form an expert on the subject. I just stumbled on this design a couple of months ago. I plan on posting the pages from the books I found references to it in. Then I’ll try to put it in modern English as best as I can. Anybody with gasifying experience, or knows chemistry, or thermal dynamics can correct me if I get anything wrong.

I’ll have another thread in projects covering the building of a Riche’ style retort. I will probably be making some slight modifications, and possibly testing some theories on that thread. And sharing my general interest in gasification.

I’m away from my computer for a couple of days, so I can’t upload any of the images or notes I have about it right now. So stay tuned for more in a couple days.

f_pal · October 7, 2019, 4:22am

trigaux · October 7, 2019, 12:46pm

Hi Nathaniel
please excuse me to use your topic . But I really like your search
I built this autoclave, it is not a “riche” but has some points in common with a riche

Thierry

Grimm · October 7, 2019, 10:18pm

It distills the wood, like the Riche’, but I think what makes the Riche’ unique to other distillation retorts is the tar cracking red hot charcoal zone. I think it is that ability that makes it so potentially useful. But that’s just me.

Someone that wants bio oil, or pine tar, or anything else, might want a different setup. Like yours seems to save the liquids, and use the gasses to keep it running. What are your plans for the liquids? Have you considered starting a thread in the science category, or maybe the charcoal category, about distillation products? Maybe asking what others have done?

trigaux · October 8, 2019, 12:11am

I would like to use the wood vinegar (pyrolytic liquid separated from the tar by decantation) in drop in the nozzle of my carbon gasifier (to control the temperature of the reaction and enrich the gas)
plant tar has a lot of property (antiseptic, wood protection …)

abnervalbuena · October 8, 2019, 7:51pm

My comment on this link explains why I try to colect Wood Vinegar. It´s something to tke in account. I think

Grimm · October 10, 2019, 1:28am

From: A Textbook on Gas, Oil, and Air Engines by Bryan Donkin

Grimm · October 10, 2019, 1:36am

From: Gas-engines and Producer-gas Plants by Rodolphe Edgard Mathot.

Grimm · October 10, 2019, 1:46am

From: A Treatise on Producer-gas and Gas-producers by Samuel S. Wyer.

Big one on the left is something else if you missed the caption.

The unit on the right is a different design by Riche’.

k_vanlooken · October 10, 2019, 2:33am

Hi Nathaniel,

i enjoy that people do read the “old” books and learn from that

I have a older thread with a link to my library on google drive. Feel free to look around in them.
btw, your book is in it to

f_pal · October 10, 2019, 3:49am

Do not forget the Guénot gasifier, which is much smaller than the rich but also powerful in distillation in a retort.

Grimm · October 10, 2019, 1:08pm

Just realized, I cut off a good chunk of the bottom of two pages from A Textbook on Gas, Oil, and Air Engines. Sorry about that. Here’s the whole thing again.

And thank you Francois and Koen for sharing what you have!

Grimm · October 10, 2019, 1:36pm

Here is a (overly) simplified sketch to help illustrate what I think is the main principal of this design.

Disclaimer: It looks like Riche’ was a tinkerer, like many of us. There seems to be multiple iterations of his gasifier. This sketch is just to highlight some of the more interesting principals.

I first learned about the Riche’ from a book How to Convert Wood into Charcoal & Electricity by Richard H. Buxton (I miss Lindsay Publications). But he fails to mention the cherry red reduction zone in his book. Seems he missed that idea because he mentions having a lot of issues with tar gumming up his engine. I missed it myself the first time I read through one of the old books. It is the heart of Riche’s designs.

Not every retort has to be a reducing (red hot char) retort. Multiple standard retorts could feed the reducer. The ten inch diameter suggested in the books probably only applies to the reduction retort just to ensure that the reduction zone is turning cherry red all the way to the center. The distilling retorts could theoretically be any size or shape you want, as long as the reducing retort could handle the gas flow.

Fresh fuel (wood, switch grass, etc.) could be put directly in the reducing retort, which would probably increase gas production. Or charcoal could be put in from the distilling retort, and the reducing retort would just be used to crack the tars. Used in that configuration, I don’t think the charcoal would be emptied from the reducer. A small amount would be consumed in the reduction process, and the retort would just need topped off from time to time.

taitgarry00 · October 10, 2019, 2:05pm

The description states that the cast iron didn’t last long, which makes sense. That was pre stainless steel time, the right grade of stainless will probably work much better in that application. Either that, or make a flanged disposable section subject to the extreme heat…

Grimm · October 11, 2019, 3:05am

One book mentions a retort life of 8 months. I don’t think the wall thickness is mentioned, and neither is the amount of run time during those months. So there’s no frame of reference for what you could hope for from a home made unit for personal use. The metal is highly prone to rusting because it’s kept red hot and has acidic fumes flowing through it.

I agree about the stainless, or the replaceable part. After I build a proof of concept model, and a couple more test models, I want to build a nice big one with one of those two, or both features. Hopefully I’ll get the proof of concept started this weekend.

It may only be wishful thinking, but in the end I want something about the size of the gasifier in Francois’ thread about cogeneration. You know, the multi story thing with a conveyor system to feed it. There’s a ton of small lumber mills around me.

Neal · October 11, 2019, 3:24am

In case you are interested in what one looks like here is a photo

Neal

d100f · October 11, 2019, 3:36am

Wow Neal , that’s some fine looking machine , hope your in a position to tell us more about it or maybe even a video of it running .

Dave

d100f · October 11, 2019, 3:40am

Oh and i almost for got to say it so … welcome aboard from Downunder

f_pal · October 11, 2019, 4:28am

Hello Neal,
Very interesting your system, and what I like most is simplicity.

Looking forward to discover your work,

Neal · October 11, 2019, 5:03am

And it is transportable: