[Stoves] An Old 'Rocket Stove' from the 1970s

Fri Feb 23 21:17:34 CST 2024

Julien, 

Thanks for the memories. I met Dick Hill in 1979 when we worked together to present a panel at the first ASME conference on wood heating appliances. The ASME was involved in discovering wood heating following the energy crisis of 1973. We saw thousands of “tin wonders” made to heat homes with wood that were emitting black smoke into the air. My friend Dr. John Cooper, then at the Oregon Graduate center, found that 60% of the respirable particulate in the Portland airshed was from wood smoke so he convinced ASME to hold a conference or wood heating appliances in Portland, Oregon. I was the local representative and Dick was the seasoned ASME member. We organized a great panel with people, like Dr. Jay Shelton, and Skip (ACS) Hayden, Combustion and Carbonization Research Laboratory, Canada, who were active in improving wood stoves. I learned a great deal from Dick at that time and in the years that followed. He was a well liked and respected professor at the University of Maine in Orono. I have since met and worked with many of his graduates. 

Dick incorporated a lot of sound combustion principles in the Jetstream. On that is not described was orienting the forced air so that the air jets impinged on the wood like blowing on the coals. This stimulated the evolution of gases and burned the char in direct contact with air, like blowing on a fire. The gasification was then followed by staged combustion at high temperatures as described in the information you cite. We were tempted at the time to incorporate Dick’s Jetstream in our home office hydronic system. It is not surprising that later stoves deployed similar concepts that dick used in the JetStream. It is also not surprising that Hampton couldn’t sell many units. Household and commercial scale boilers at the time were not as popular as they were, and still are in Europe. It took several years for the European stoves to catch on in North America. We usually saw them picked up first in Canada, like our friends on PEI who we had worked with burning straw.  

The conference led to the evolution of the Oregon smoke charts and emission standards which reduced the number of inefficient stoves on the market and influenced what became the EPA standards. We had lively discussions in the 1980s in a chat group I maintained on a “dial up bulletin board” (BBS) which I later moved to this list in about 1996 with access to the internet. The focus at that time turned to cookstoves. 

We met Larry Winiarski in 1976 when he built us a gasifier for straw. (I had known his professor at UC Berkely when he was working on pulse combustion.) We often discussed basic combustion principles as he did for the rest of his life and to the benefit of us all.    

Kind regards             

Tom

From: Stoves <stoves-bounces at lists.bioenergylists.org> On Behalf Of Julien Winter
Sent: Friday, February 23, 2024 5:19 PM
To: Discussion of biomass cooking stoves <stoves at lists.bioenergylists.org>
Subject: Re: [Stoves] An Old 'Rocket Stove' from the 1970s

Hi Folk;

Richard Hill patented his stove in 1981.  Vertical Feed Stick Wood Fuel Burning Furnace System.  US Patent 4,473,351.   The patent was assigned to the University of Maine.

https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/4473351

Besides referencing a 1944 patent using a vertical stack of wood fuel, there is no reference in Hill's patent to any prior art that burned stick wood only at the bottom.

There were attempts to commercialize the stove, and they are described in this Wikipedia article:

https://en.wikipedia.org/wiki/Jetstream_furnace

The first company went bankrupt because they over-spent  their financial capital on North American promotion.   Howerever, the stove didn't seem to succeed in the long run.  I suspect that was because of their inclusion of a water heating system and dependence on electricity made the stove too complicated for the market.  Oil-fired furnaces were easier to use.

If they had a natural draft, hot air furnace, history shows that they would have succeeded.  That was what got me and our neighbors excited about the Harrowsmith article (in the previous email).  In the 1970s, there were still a number of historic farmhouses that heated using a wood fueled convection furnace.  They looked like a huge octopus in the basement.  We had a regular schedule of taking down the flue to clean out the creosote.  All the same, the occasional house was lost to a chimney fire.  We were swimming in wood fuel, and every spring we had to clear the farm fields of dead-falls.  We were always worried that our 150-yr-old farmhouse would burn down.

Richard Hill's contribution to biomass combustion seems to have been forgotten.  

Cheers,

Julien

On Wed, Feb 21, 2024 at 10:15 PM Julien Winter <winter.julien at gmail.com <mailto:winter.julien at gmail.com> > wrote:

Hi folks;

When I got involved with TLUD stoves back in 2012, I also saw rocket stoves, I knew I was looking at something familiar.  This has been bugging me ever since, and I had to go back to see if my memory was right. 

Through the 1970s and 1980s, my family had a cow collection in Eastern Ontario, Canada.  We used to subscribe to a country living magazine called "Harrowsmith." Every month, we would read the magazine from cover to cover.  One issue in 1980 described a new stove that was developed at the University of Maine in the 1970s, and commercialized in Prince Edward Island, Canada.  

Mariner, R. 1980.  "Superfurnace: It Walks, It Talks, It Crawls on Its Belly Like a Reptile …"  Harrowsmith, number 27, volume 7, April 1980 

What a name for an article!   I have attached a copy.   I discovered that there are devoted fans of Harrowsmith that have kept all their old copies, and they have a Facebook page.  If you have a vague recollection of an article, they will start sleuthing for it, then post photos of the pages on Facebook.  That was a lot more efficient for me than driving to Trent University to look through microfiche film.  

Back in 1980, I wanted to build one of these stoves, but I ended up going to graduate school.

The stove was based on the research that is reported here, 

Hill, RC 1979 Design, Construction and Performance of Stick-Wood Fired Furnace for Residential and Small Commercial Application US Department of Energy, EC 77-S-02-45. 30 p.

Hill's stove was a forced draft stove, but in principle, he had designed what we now call a rocket stove.  It has primary air burning char and pyrolyzing wood, with gases burning up stream.  The wood is preheated and dried before it starts to burn.  The article says that you can virtually burn green wood.

You can find a copy of Hill's bulletin on-line, and I think Bioenergy Lists has a copy.

Cheers,

Julien.

-- 

Julien Winter
Cobourg, ON, CANADA

-- 

Julien Winter
Cobourg, ON, CANADA

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