Using heat reflector plates to improve performance on grain.

It may be warm stateside but we just got our coldest July day on record; 32F. Still not cold by your standards but terrible for us Aussies....
Our standard fuel is high energy, low protein wheat. This burns completely different to wood pellets and it is essential to hold the temperature in the fire bed (clinker) as opposed to blasting air through the more volatile wood pellets.
Our standard burnt pot, spreader bar and catching wings look like this;



The wings are only there to catch grains of wheat which bounce off the divider rod. We have begun putting in a new plate at the front of the pot which folds over the top of the pot and wings to reflect heat back into the pot.
This has been very successful in lifting clinker temperature and therefore creating a denser clinker which increases run time. The problem is that it effectively blocks most of the view of the fire. So I have been working on an alternative.
I have made a pair of simple reflector plates which sit around the pot and lean in. This effectively stops jumping grain from getting out and the reflected heat work just as well a the the front mounted plate.
Here is how it looks;



The flame is easy to see but the interesting thing is that flame behavior is different to the standard fire. The pot is rectangular running across the stove while the aperture of the deflector plates is rectangular from front to back of the fire. What we are seeing is a gentle rotating of the flame which then tends to run it straighter up the fire chamber.

So the "pinch and twist" of the flame path seems to work well and the reflected heat into the pot definitely promotes better clinker health. This is of no use to pellet burners but anyone on corn or wheat should definitely give it a try. We have been able to push our low running time from 17-25 hours without any other changes. We will continue running like this to see if there are any drawbacks but it all looks good at this point. I have ordered up 50 sets of 3mm (much heavier than the ones shown) deflectors to run in local stoves to get more feedback but I reckon this simple tweak will be a winner.
Once I am happy with it I will do a YouTube video for all our other users as it is a simple retro change.

 

Somewhat similar to what I have done to run the Hazelnut shells.
We don't need the elaborate sheet metal but do have to modify the grate to catch the smaller shell pieces and have added a spreader bar.

Looking good

 

Here is the video,
Enjoy....

 

Have made a minor adjustment to the deflector plates and now sit the spreader rod on top of the overlapping plates.
This allows the front to lean in more. Looks neater and has no impact on the rod.

 

Hi Chickenman
Many multi-Fuel pellet stoves in the states that burn corn and wheat have fuel stirrer rods in the burn pot to break up the clinkers. The storer rod is usually connected to a chain and sprocket to a second auger motor and runs continuously to break up the fuel.
What do you think? See pic attached below.

Here is a video on removing a fuel stirrer also called an agitator in an M55 Multi- Fuel Enviro FS pellet stove.

 

Hi Don.

We have found it is better to let a clinker form as the clinker is a concentrated waste whereas the agitated waste is light and fluffy and takes up a lot of area.
We were running a Seraph (mighty fine stirrer stove) in tandem with an old SnowFlame non-stir and the waste from the Seraph was just a pain in the butt. We were forever throwing out buckets of ashy stuff compared to the SnowFlame or Nero with a small pot sized brick once or twice per day.
You can see on the videos that we are trying to get the biggest, heaviest clinker possible to lengthen burn time and the new wings really help in that respect.
The other thing about stirrers which are a bit off putting is the complexity. Better keep things real simple.

 

Yes, Simple is better.
Also we use FireBrick backing on the back and side walls to increase the heat. I see you already have that and are taking it to the next level with the wings. Good Work, I sure that will catch on!

 

Yes I think the vermiculite helps to reflect more heat through the glass. The heat exchanger channel in these stoves struggles to extract the maximum amount of heat if you are really stuffing the fuel in. Especially so with pellets where we can really up the feed and air rate.
We have an exhaust mounted thermocouple and running wheat at maximum feed rate sees a heat out put of 24,000btu with an exhaust temp of 200F. The feed in rate is around 2.4lbs/hr. Using pellets we can force the feed in to 4lbs/hr but the exhaust temps rises to 275F. To avoid condensation we need an exhaust temp of 175F so effectively on high (on pellets) we are wasting 100F.
So owners sometimes try wood pellets and initially think that the performance is better as the stove is hotter to the touch and the air coming out is warmer but generally they come back to the wheat once they realise that the increase in fuel consumption and cost doesn't translate to an equal increase in heat.
Pellets have the benefit of a wide burn range. With wheat the band is narrow and low temp burning is fatal for wheat as you use the heat in the clinker to keep the fire running. This is where the heat reflecting wings help hold the clinker temp up and we have our controls set so that if the exhaust temp drops below 175F the room fan stops to allow the firebox temp to rise up to 190F before restarting.
Burning pellets is easy in comparison to grain and the principal behind the 2 burns is completely different. We get lots of inquiries from owners of different pellet stoves wanting to change to wheat and they cannot understand how it is just not a matter of cleaning out the pellets and tipping in a bucket of wheat. It has taken us years to get the right design of both machine and controls as well as really fine tune the operation. Also we are careful to listen to any suggestions from users to improve things.
THe stirrer stove is a way of making the burn more like a standard pellet stove on grain but the waste is too great a problem for my liking. Plus it is more fun to tinker...