Multi-Fuel Furnaces for a Nursery.

A customer of mine owns a large farm and plant nursery. The nursery consists of greenhouses and over four dozen buildings which are spread out over 300 acres. They contacted me to engineer a heating system for each individual building that is capable of burning wood pellets and coal. The farmer purchased a pellet making machine a decade ago which processes his biomass into a pellet and he is a frugal man who likes to get his full return on his investments. This is a third generation farm and he wants to make it a fifth generation farm if he can help it.

I've given the farmer several quotes, one of which proposed using Alaska 140's with the underfed stoker like an EFM. The Alaska is capable of burning wood pellets or coal but they are expensive, especially when you need fifty of them for over two hundred thousand bucks.

I've decided to build a prototype stove, small and simple, that uses a miniaturized underfed stoker that produces less than 100k btu's. I found this board in the Summer when I started doing my research and I'm looking for feedback from the many experienced folks on here. I've read many great posts from electricians, engineers, plumbers, welders and every other skill-set known to man. If anyone has a thought or comment, please type it, no impolite reply will ever come from me.

The two fuels have different requirments to be happy. I believe you will just frustrate yourself trying to design something that could be happy with both. I recommend you chose one and save yourself a lot of grief.

coaledsweat wrote:The two fuels have different requirments to be happy. I believe you will just frustrate yourself trying to design something that could be happy with both. I recommend you chose one and save yourself a lot of grief.

True Story.

Design for coal and add pellets into as a mixing element.
It doesn't need to be complicated.
It has been done before... Was a pellet stove that burned coal, or was it coal stove that burned pellets? See Harman 44 magnum.

If you were to use boilers you might be able to group the load and use one unit for several buildings, thereby utilizing a larger unit (efm 520) cutting cost and maintenance / tending time. If the guy wants to be in the pellet business get a wood pellet unit , If he wants to be in the nursery business and save some cash on heating buy a coal stoker that will "tollerate" wood pellets . I don't see any advantage to having a seperate unit for each building unless they are great distances apart. Good luck, sounds like a fun project!

In this neck of the woods -- we have lots of waste paper - such as these folks http://www.pelletamerica.com/about.html - they sell semi loads of pellets the size of golf balls and skids of more traditional sized pellets - the BTU contend is far lower than wood but that's not the point

The material is sold to large solid fuel consumers and is mixed with the coal as it is introduced to the boiler - the result is less hard ash and less emissions to scrub

I did this with my corn boiler[using home fuel pellets] --- the clinker produced from straight corn fuel was extremely hard - but the clinker from a mix of corn and pellets - or better yet was a mix of wood pellets and paper pellets -> because the cost of BTU produced was less than wood alone [ paper pellets were cheep]
[ as McGuiver suggested above ]
Now all it will take is a delivery system involving two bins [ one coal and one xxx] and some method to control the mix- again this intigration should occur close to the fire box as the home made pellets will not survive long in the auger.

Kind regards
Sting

HeatTech wrote:A customer of mine owns a large farm and plant nursery. The nursery consists of greenhouses and over four dozen buildings which are spread out over 300 acres.

What is the expected heat load?

It sounds like all of these buildings expect to be heated? You may be better off running underground piping to heat exchangers (maybe modine type units or radiators) to each building than pricing out 50 or so individual alaska stokers. Keep in mind that each alaska will need tending, fueling and ashing. I think the management overhead will be tremendous.

If you could find/build space on the property that is advantageous not only from a piping standpoint that can reach all points in the property but also from a fueling standpoint. Again not sure what your heat loads will be but 4 dozen buildings over 300 acres; well I think you may be looking at having fuel trucked in instead of a few tons at a time. The building would have to have the room for a truck delivery and space to dump perhaps as well as the ability to truck away the ash.

Perhaps you need a few EFM 520s, Axemans etc...to give you the BTUs you need or one big boiler plant. Check out this video of the Blue Flame Stoker which uses a continous chain grate to combust solid fuel. From the video, it seems like it can burn nearly anything solid and you may save the farmer from needing to press the biomass into pellets.

My .02 is to not try to reinvent the wheel, because many 'way brighter' than us have been down that road. Existing equipment can meet your requirements, however a dual fuel capable machine is a device that does neither very well because of burn characteristics, Remember grouping heating loads with a couple heat plants makes a 'User Friendly Product' AND is more efficient in terms of cost of operation AND easier to maintain/service/and monitor. KISS philosophy once again rears it shiny head...........

I'll try to answer your questions, I apologize if I forget something while typing. Thanks everybody!

1). The distances between the buildings make it impractical to connect them via underground plumbing. The topography is hilly with substantial shale and clay intermixed.

2). Manpower for tending the stoves is available. They are in every building daily watering the plants etc.

I've thought about purchasing underfed stokers from a supplier and mating them to a stove body welded together locally. The EFM S-15 stoker has been out of production for decades and the tooling is gone. Alaska may be interested but I'll never get anywhere with Harman's bureaucracy.

Use the fuel that is more readily available and cost effective in the area and choose systems around it. Blending fuels will add complexity and problems and cost to the project that you don't need. Reinventing the wheel is not usually a success story.

A big DITTO on what WN & CS posted. To some degree or other, we all suffer from the concept of "The Magical Magnifying Mind" on occasion:) again---KISS

Freetown,

If Dane Harman ever listened to people telling him to "Keep It Simple Stupid" he never would have sold his company for 30 million dollars. Dane has developed some of the most innovative and ingenious wood, oil, pellet and coal stoves ever designed. Innovation paves the road to success, not sitting idle while your competitor designs a better solution. I'm in business to do business, the customer asked for my help and I'm doing my best.

HeatTech wrote:Freetown,

If Dane Harman ever listened to people telling him to "Keep It Simple Stupid" he never would have sold his company for 30 million dollars. Dane has developed some of the most innovative and ingenious wood, oil, pellet and coal stoves ever designed. Innovation paves the road to success, not sitting idle while your competitor designs a better solution. I'm in business to do business, the customer asked for my help and I'm doing my best.

How many of his designs were dual fuel and/or burned a blend of both? I admire your determination but warn you. You are in business to make money and keep your customer happy to continue doing so. To pursue this fantasy will be a costly mistake in more ways than one.

Damn it cs, ya beat me--the point here, in case you've missed it ht is that multi fuel stoves have proved themselves to SUK--PS--here I was getting the feeling that you were in business for the sole purpose of making MONEY--PPSS--I've always liked to run with that concept of-"keep it simple spiritually" Have you been to S. Otselic & really sat down & talked to Arnie about this undertaking?

Sometimes you can make money by holding patents to ideas that may not have been successful for you, but could be for someone else. Federal Court is no friend of mine. Withdrawing a patent is painful, in more ways than one.