Black smoke from steam engines

[Steamchick]

Look up the American Big-Boy locos. I am sure they were chain grates, as 2 humans could not keep them fired for long, hauling coal through the mountains of Virginia?
K2

 

[Steamchick]

AJ?: Actually "What size of boiler" do you want to feed?
K2

 

[Steamchick]

Is your boiler as big as this with a screw feed for coal? - and blower?

K2

 

[Steamchick]

Big Boy drawing with chain grate...

 

[ajoeiam]

AJ?: Actually "What size of boiler" do you want to feed?
K2

Hmmmmmm - - - - ah do believe that I mentioned that in my last missive - - - - thinking somewhere between 75 and 100 kW.

So quite a bit smaller than either of the two comparables you pictured.

 

[Steamchick]

Thanks AJ. I asked again, as sometimes the spellchecker changes what I type, and wanted to confirm that the sizes in post #20 were not a typo.
The reason that chain grates were quite common was that maintainable was relatively easy.. given technology when they were used. Considering locos used them - when firing was bigger than 2 firemen could manage for a shift - the reliability must have been pretty good. You would not want the coal-feeder to fail on your Big-Boy, half way up a big incline when you have a full coal train behind you!
Screw feeders were used in industry, as in powering mills, pumping stations, etc. (Examples at museums in the UK). I think also on later marine boilers for steam ships that were coal fired.
I have not done any calculations on how much wood chip you'll need to feed, but I guess you can work that out, from the type of wood, size of boiler, expected efficiency, etc.
The boiler can be roughly designed by one of the Chinese boiler companies on the web, in one of the links I posted.... I think?
Do post more about your development when you have something more...
K2

 

[Richard Hed]

Grew up where our primary heat was a wood stove.
Using similar is somehow not so appealing - - - except I'm trying to re-think the stove.
The idea is to fire wood chips - - - like landscaping ones not the teeny weeny stuff that is sold for 'home' use.
I get the sensors stuff - - - what I'm trying to figure out is how to feed (that is not simple - - -needing to use the under fire air to get good burn) and how to do a clean burn of the gasses produced in the combustion.
I'm a thinking of something like a high temperature material heavy mesh for the grate (to let ash fall through yet not impede the under fire air).
Where I'm striking out is how to force the burn of the gasses produced.
Ideas - - - suggestions?

TIA

Check out the "rocket stove". It burns very; cleanly. I built one half way just to chek out the claims. On mine, I built the wood holding (fire box) a little too small. Have not gotten past the basic frames part

 

[Steamchick]

I have seen a few rocket stoves on't web... but most only seem to be for heating sheds and workshops - taking a lot of "Human input" with the fuel feed. I understand they are also of the 1 to 10kW power... for heating water, not steam. Planning for "somewhere between 75 and 100 kW. " (Post#20) needs a much larger power feed, and the screw feeder seems to be a favourite to me. I am sure a screw feeder from an agricultural supplier should be the right sort of size, which can be controlled by motor speed.
wood chip screw conveyor - Search (bing.com)
The air supplied by a blower through the fuel at the base of the fire.
Here's an example of a water boiler about 1/4~1/3rd the size required by AJ... The price is a good reason to make your own!
Atmos P25 Incl. Burner And Screw Conveyor 2,0 M | eBay
Comment on coal feeder systems, etc. within this:
Coal Based Fuel Feeding System for Boiler (instrumentationtools.com)
Or this?
Optimizing Process Parameters of Screw Conveyor (Sugar Mill Boiler) Through Failure Mode and Effect Analysis (FMEA) and Taguchi Method | SpringerLink
Any use or interest?
K2

 

[ajoeiam]

I have seen a few rocket stoves on't web... but most only seem to be for heating sheds and workshops - taking a lot of "Human input" with the fuel feed. I understand they are also of the 1 to 10kW power... for heating water, not steam. Planning for "somewhere between 75 and 100 kW. " (Post#20) needs a much larger power feed, and the screw feeder seems to be a favourite to me. I am sure a screw feeder from an agricultural supplier should be the right sort of size, which can be controlled by motor speed.
wood chip screw conveyor - Search (bing.com)
The air supplied by a blower through the fuel at the base of the fire.
Here's an example of a water boiler about 1/4~1/3rd the size required by AJ... The price is a good reason to make your own!
Atmos P25 Incl. Burner And Screw Conveyor 2,0 M | eBay
Comment on coal feeder systems, etc. within this:
Coal Based Fuel Feeding System for Boiler (instrumentationtools.com)
Or this?
Optimizing Process Parameters of Screw Conveyor (Sugar Mill Boiler) Through Failure Mode and Effect Analysis (FMEA) and Taguchi Method | SpringerLink
Any use or interest?
K2

Ja - - - a rocket stove is a tool for minimal fuel consumption for a small room - - - - not really thought for large space nor for hot water production.

My idea sounds large until it is placed beside my present heating system - - - just for my residence - - - - that's rated at 65 kW (an electric furnace).
A hot water system in this size isn't actually that large (imo) especially having worked inside the circa 200 MW coal fired boilers common some 600 to 750 miles to the west (and somewhat north) of me.
The 'coal based fuel feeding system' is using a screw conveyor (auger) to push up material into the burn zone.
That would have to be one carefully speced auger to get it to stand up the the heat generated.
I was hoping to have something where the fuel would be dropped into a rotating 'lock' which would push things out onto some kind of ramp so as to minimize the chances of fire back into the feeding system. Not clear as to a good way of minimizing that risk but am working on it!

An interesting article - - - - will work through it and see what its saying (just grabbed a copy and did a quick lookee see.

Thanking y'all for the ideas and the tips!!!

 

[Steamchick]

Having seen screw conveyors feeding boilers.... the coal hopper was closed with a lid. The screw drove the coal along the feed-pipe. Further along the blower blew air into the feed-pipe. The coal and air went through a bend so was fed vertically up into the combustion chamber, where it spilled-out into the base of the fire. The fire stayed above the fresh fuel, and didn't burn back down the screw feeder. The coal slipping away from the feed hole was burning over a grate where the ash could spill through into the ash pan. The only combustion air was blowing through the coal at the end of the feed pipe.
K2

 

[ddmckee54]

Have you checked into how some pellet burners with power feeds work? Some of the burners that I have seen for them feed from the bottom fire pot. Combustion air is forced up through holes in the bottom and sides of the fire pot and through the pellets. The incoming pellets force the ash and klinkers out the top of the fire pot and into the ash pan.

Don

 

[Steamchick]

Thanks Don,
A simple explanation of what I was trying to describe!
K2

 

[MacKendrick]

I like a little black smoke coming out of the stack but somebody should explain that the reason to reduce the black smoke is not environmental it is to reduce the soot from the smoke from coating the tubes and reducing the boiler efficiency.

 

[Steamchick]

Hi Mackendrick. I agree it is not environmental for small models, but we had serious complaints, that had a negative impact on our relationship with the park and adjacent residents, when a 1/2 scale traction engine was over fuelled in error, and we filled a street with black smoke. The fire brigade were called and when they arrived the smoke had cleared. But no-one was happy for 10 minutes or so!
So I suggest you do minimise black smoke to keep the "environment" - or the people within it - from finding ways to stop your activities.
K2