Burning Wood Pellets

[andrew52]

Hi Mike, the pellet feeder cycles around every 15 seconds on high fire and about 2.5 minutes on low fire which just keeps the fire burning but does not blow the safety valve if the engine is not running , I adjust high fire so the boiler runs at about 80 psi with the engine full ahead . I have a pressure switch which switches the system to low fire at 85 psi and back to high at 70 psi which makes it automatic ,it also switches the fan to low or high .
The tricky bit was to keep the fuel /air ratio correct when the system changes from low to high I needed a delay on the fan to give the pellets time to start burning and again to give them time to burn down when it switches down to low fire to avoid smoking, to simplify this and avoid too many timers I fitted a PLC controller so the timers and delays could all be programmed the only down side of this system is on low fire with the 2.5 minute cycle to avoid blowing the safety valve it smokes slightly when the pellets go in because the fire is almost out.
The blower is a plastic marine type bilge fan with an adjustable voltage regulator the wiper motor was from a small car and both draw about 4 amps total the new system draws about 2.5 amps because the motors are more efficient .
I usually light the fire when I leave home and leave it switched to low fire to warm up on the way to the ramp and if I am in a hurry to get steam up I stop 15 minutes from the ramp and switch to high fire so I have steam when I arrive .
I have a 90 watt flexible solar panel on my canopy and the battery is always fully charged.
I am currently working on Mk 3 control system which should be the rolls royce system based on an Arduino Uno programmable controller with a stepper motor on the pellets and a quad copter motor fitted to the blower to give a step-less continuous flow of pellets and variable fan speed with adjustable ramp rate up and down , I have it running on the floor and hopefully in the boat tomorrow .
I suggest if you are interested in pellet firing make a prototype from a couple of tins like the one in my video and hand feed the pellets and play around and see what happens the blower I used was a small .3 amp brushless blower like a large computer cooling fan which was plenty for the prototype but my boiler has too many leaks so I needed a bigger one for the boat.
You could get away with the simple timer system without a pressure switch and simply switch it to low when the pressure builds up .

[Lopez Mike]

Since I deal with Arduinos and Basic stamps regularly in my business, I am mentally working on a quite different implementation of your ideas. I get a certain satisfaction from having as few electrical infernal machines aboard as possible.

If I could get such a burner to run on natural draft, the remaining design problem would be the feeder. I have been doing some back of the envelope sketches of a design that works with a reciprocal motion thus that I could drive it with a steam cylinder from a feed water pump.

I don't need to automate it so much as avoid having to pull a lever ever time I want to dump a few pellets in the fire. When I'm running hard now I have to throw in a few hunks of wood every few minutes anyway.

I have several Stuart 10V engines on the shelf as well and driving you rotary feeder through a worm gear might work too. Do you think that a slowly rotating wheel would work? Or would too much air go the wrong way through the hole in the feeder wheel if it were creeping around?

I will be watching the local dump for a suitable pot and lid so I can at least cobble together something to see if natural draft could work at all. If I kept the bottom holes small and made the side holes larger might it burn without a fan? I suppose the fan could run off of the small steam engine running at constant or at least higher speed and change the duty cycle or speed of the feeder.

[andrew52]

Hi Mike, been there and done all that ,the reason I use forced draft is to get enough air flow and be able to control the air flow easily and accurately, I tried it with a 1 mm steam jet up the funnel but it used too much steam but I keep a large spoon on board so if the electronics fail I can use the steam blower and spoon some pellets in to get home .
The pot I use is an 8" cast iron pot from the local outdoor shop with the handle cut off.
There is a very good English online manual on burning pellets I will dig it up and post a link.
One reason I went with the Electronics was because they are by far the biggest development in technology and I think things like steam engines need to be revisited to see what a difference modern electronics can make to them like car engines etc.
My engine and boiler are traditional polished bronze and wood which people love with the electronics out of sight so most people don't even see them.
I sometimes think my setup has completely leapfrogged the internal combustion era by burning 100% renewable carbon neutral non fossil fuel something thousands of car makers have been trying to do for decades and spent billions on !
If you can handle the electronics you are cruising , do you know anything about the American Ruggeduino ? I accidentally blew up an Arduino and have heard the Ruggeduino has much better protection but only available in USA ?

[DetroiTug]

Quote: " I think things like steam engines need to be revisited to see what a difference modern electronics can make to them like car engines etc."

Like it is with most things steam, it's been done and many programs with varying levels of sophistication and expertise are ongoing. The end result is always the same, no way is a small scale steam plant ever going to reach the power output to fuel consumption ratio of a deezel or any internal combustion engine for that matter. Then there is the "brickwall" - how to keep the entire plant from freezing in winter weather.

The only way steam will ever make it's way back in to mainstream small scale transportation is to find a source of heat that is free, can't be used any other way and easily stored. In other words, not likely going to happen.

Quote: "I sometimes think my setup has completely leapfrogged the internal combustion era by burning 100% renewable carbon neutral non fossil fuel something thousands of car makers have been trying to do for decades and spent billions on !"

Research "wood gasification" It was something developed in post ww2 in Europe in areas where gasoline/petrol were not available. Whereby wood chips are heated and the gas admitted in to an internal combustion engine. People routinely ran there cars with that system. I know a guy here local Terry Grzyb, that has a Ranger pickup that runs on it - drives it back and forth to work, even his riding lawn mower runs on it.



More details of your Arduino controller layout and it's program would be great to read and have a look at. I have one, but I haven't learned how to use it yet.

-Ron

[andrew52]

Hi Ron, yes I am aware of the brick wall and am not trying to knock it down but just like computerizing IC engines the electronic control doesn't necessarily make the engine more efficient except for cutting down on wasted fuel but it makes it much easier to drive the boat just as it would greatly improve the wood gas I C setups.
without worrying about stoking and boiler pressure it doesn't make much smoke or soot up the boiler tubes and the fuel doesn't take up as much space and does not bring ants and spiders on the boat and make a mess like coal and produces almost no ash.
we can go ashore for lunch or whatever and leave the fire burning to maintain steam pressure and have it burning on the way to the ramp .
One of my favorite things is to leave the boat tied to a marina with the engine just ticking over and stand back and watch people admiring and taking video and pictures and listening to young fathers explaining it to their young children.
A friend Wally Mounster spent his life trying to invent a more efficient engine which normal people couldn't recognize but I have deliberately kept my engine and boiler traditional and concealed the modern bits and people love to watch it and the fact it is so quiet and smooth.
There is at least one way to prevent freezing in winter ,move to Australia !
I hope to run the new control system in the next couple of days and will share some pics .
This doesn't happen with a diesel ! (I was trying to point out my passenger dozed off while watching the engine)


I love it so d i e s e l is classed as a profanity on this forum when you type it it posts "smelly long-chain hydrocarbon" are there any others I need to know about ?

[andrew52]

Hi Mike and Ron, I understand the deezel wasn't a typo now , I have my Mk 3 Arduino based pellet control system working now and it works beautifully ,I have fired the boiler about five times over the past two days to make sure there are no bugs (and because its fun to fire it up ) it has worked perfectly from striking the match to 90 psi of steam without a hint of smell or smoke with the boat inside my workshop .
I have included potentiometers to adjust the pellet feed rate on high and low fire and blower speed on high and low fire and also the ramp rate from high to low and visa versa but since I adjusted them on the first run I haven't needed to touch them so maybe they can be simply trim pots inside the control box in case any adjustment is needed in future or maybe I can simply program the values into the Arduino and not bother with them at all but time will tell. I now realize as the pellet feeder and blower are now programmable through the Arduino there are many options for a control system from a simple knob to manually turn the fire up or down so the boiler holds pressure while the engine is stopped to holding the desired working pressure at full throttle . I have included a steam pressure switch which turns the fire down at 85 psi and back up at 80 psi to make the system automatic, the ramp rate adjustment is to give the fire time to build up so the higher feed rate doesn't smother the low fire and gives the pellets time to burn down when changing to low fire to avoid smoking.
I left the boiler on automatic for 4 hours without the engine running just topping up the pellet feeder occasionally with no problems yesterday.
I will clean up and take some pics for you soon ! I will also polish up my blackened brass funnel cap and see if it stays polished now that will be interesting !

[Mike Cole]

yes now works fine on a chome book

[andrew52]

Hi Mike,Mike,Ron and anyone else interested I have attached a brief video of my pellet burner ramping from low fire to high (please excuse the blower noise I think I had the camera volume too high and some stills of the feeder and engine and pellet bunker and control panel.

[andrew52]

And a pic through the fire door (pardon the house keeping but I have not removed any ash for about 12 months)

[cowiepeters]

Love your work Andrew!

Seeing it in action in Hobart was magic

Thanks

Peter Cowie