Air Requirements for Coal Combustion

What volume of air is necessary, per minute, to burn one pound of anthracite in one hour?

0-1 gallons per minute
5
19%
1-3 gallons per minute
2
8%
4-6 gallons per minute
4
15%
7-10 gallons per minute
5
19%
11-15 gallons per minute
2
8%
16-20 gallons per minute
3
12%
21-30 gallons per minute
1
4%
31-40 gallons per minute
0
No votes
41-50 gallons per minute
1
4%
51-75 gallons per minute
3
12%
 
Total votes : 26

Re: Air Requirements for Coal Combustion

PostBy: VigIIPeaBurner On: Fri Nov 28, 2008 11:05 pm

Thanks Yanche. I'm sure it was an older Bacharach, I remember the slide rule. The CO2/O2 adsorbent would certainly need replacing. It sounds as though there is some experience behind your comments on applying the measurements to a coal appliance. Have you worked with them on a coal fire and is it really worth the effort of going through the steps?
VigIIPeaBurner
 
Hot Air Coal Stoker Furnace: Keystoker Koker
Hand Fed Coal Stove: Vermont Casting Vigilant II 2310
Other Heating: #2 Oil Furnace

Re: Air Requirements for Coal Combustion

PostBy: EarthWindandFire On: Mon Sep 12, 2011 9:35 pm

After just buying a Leisure Line Lil' Heater, I have given some thought to using a pre-existing dryer vent to draw fresh outside air in for combustion.

The steps needed to construct an air-supply duct is very simple and should provide enough air for the 45 cfm stoker blower.

1). Remove the existing dryer vent from the rim joist and nail a small wood frame over the top of a 6" square sheet of metal window screen to keep pests from entering the house where the dryer vent was located.

2). Screw a toilet bowl flange over the hole cut into the rim joist and then run a 4" pvc pipe inside a basement ceiling joist and hang using joist hangers. Next, terminate the pvc pipe just above the rear of the coal stove. Use screws to hold the loose pvc pipe and elbows together without the need for pvc glue.

3). Dry fit a 90 degree elbow to the pipe and run another section of pipe vertically until at a right angle with the combustion fan cage, but 2' foot distant from the stove. Connect a second 90 degree elbow and then run 4" black pipe horizontally until contact is made with the combustion fan's open squirrel cage.

Now for the questions!

A). Should I install a barometric damper into the pvc pipe to prevent a loss of fresh air should the vent ever become clogged or blocked for any reason?

B). Will a 4" pvc pipe, with two changes in direction, provide enough fresh air to the combustion blower? I assume yes since the 4" vent provided enough diameter to vent the clothes dryer. The typical plastic dryer exhaust wheel is 3" inches deep by 8" inches in diameter with about 20 curved fins but not sure about the spec's on the blower motor, looks fairly small.
EarthWindandFire
 
Hot Air Coal Stoker Furnace: Leisure Line Lil' Heater.
Hand Fed Coal Stove: Hitzer model 75.
Other Heating: Oil and Natural Gas.

Re: Air Requirements for Coal Combustion

PostBy: EarthWindandFire On: Wed Sep 14, 2011 12:44 pm

Carbon monoxide is produced from the partial oxidation of carbon-containing compounds; it forms when there is not enough oxygen to produce carbon dioxide (CO2), such as when operating a stove or an internal combustion engine in an enclosed space. In the presence of oxygen, carbon monoxide burns with a blue flame, producing carbon dioxide.

Based on the above information, it's easy to conclude that by providing your coal stove/furnace/boiler with fresh outside air via a supply duct directly to the combustion blower, the fire is less likely to produce carbon monoxide.
EarthWindandFire
 
Hot Air Coal Stoker Furnace: Leisure Line Lil' Heater.
Hand Fed Coal Stove: Hitzer model 75.
Other Heating: Oil and Natural Gas.

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Re: Air Requirements for Coal Combustion

PostBy: Pacowy On: Wed Sep 14, 2011 1:10 pm

Making sure you have enough combustion air obviously is important, but I'm not sure about jumping from the quote to the conclusion about ducting in combustion air, as opposed to, say, keeping a window open a little. I thought about doing something similar once, but the stoker pro I asked didn't recommend it. In addition to the air pressure and blockage issues, the stoker would be subjected to wide swings in the characteristics of the combustion air, including temperature and moisture content, that would have unknown impacts on its performance. I think the most effective CO protection comes from ensuring appropriate draft and ventilation, and having functioning detectors. I wouldn't rely much on the idea that perfecting the fire can prevent CO formation in any type of way that people should rely on.

Mike
Pacowy
 
Stoker Coal Boiler: H.B. Smith 350 Mills boiler/EFM 85R stoker
Coal Size/Type: Buckwheat/anthracite

Re: Air Requirements for Coal Combustion

PostBy: Rob R. On: Wed Sep 14, 2011 1:15 pm

I agree with Mike on this. Outside air and adequate amounts of air for combustion are two separate issues. The last thing I want to feed my stoker is damp air from outside. I trimmed the bottom of the basement door a little to allow more make-up air, and called it good. I admit that my house probably has sufficient make-up air on its own :roll:, but I would rather pull it through the basement than the living room windows.
Rob R.
 
Stoker Coal Boiler: EFM DF520
Hand Fed Coal Stove: Hitzer 50-93
Other Heating: Dad's 1953 EFM Highboy

Re: Air Requirements for Coal Combustion

PostBy: wsherrick On: Wed Sep 14, 2011 1:15 pm

It's not the amount of air that produces Carbon Monoxide, but; the temperature of the air as it comes into contact with the fuel. Perfect combustion results in 3 products: Carbon Dioxide, Water and Inert Matter (ash). For the hydrocarbons in any fuel to completely combust, the temperature must be up around 1800 degress and above. Otherwise you get carbon monoxide, which means half of the theoretical heat value in the hydrocarbons is lost.
It is impossible to achieve these temperatures and level of combustion in a naturally aspirated appliance. So even if the air to fuel ratio is perfect, the goal is still unreachable simply because you can't get those high temperatures without a forced draft of some kind. Also at those temperatures your stove wouldn't last very long. The loss is much greater with Bituminous Coal as it is mostly hydrocarbons. The loss is minimum with Anthracite as it has a much lower hydrocarbon content. It is mostly fixed carbon which burns at a much lower temperature, around 750 degrees or so. It's well within the capacity of a normal appliance to reach optimal temperatures to burn fixed carbon. It's nothing to lose sleep over. You still get plenty of efficiency with coal. Theory is just that. It is a level of perfection that we know exists, but: we'll never quite get there.
wsherrick
 
Hand Fed Coal Stove: Glenwood Base Heater, Crawford Base Heater
Baseburners & Antiques: Crawford Base Heater, Glenwood, Stanley Argand
Coal Size/Type: Chestnut, Stove Size

Re: Air Requirements for Coal Combustion

PostBy: lsayre On: Mon Sep 23, 2013 8:25 pm

I'll take a one shot ballpark stab at this one:

1. There is roughly 21% oxygen in air by volume
2. Air weighs approximately 0.0807 lbs. per cubic foot (per a random website I pulled up)
3. By weight, 23% of a cubic foot of air is oxygen (per a random website I pulled up)
4. 23% of 0.0807 lbs. = 0.0186 lbs. of oxygen in a cubic foot of air
5. 1 cubic foot = 7.4805 gallons
6. 1 gallon of air (at standard temperatures and pressures) therefore has 0.002487 lbs. of oxygen.
7. The molecular weight of carbon is 12
8. The molecular weight of O2 is 32
9. The percentage of carbon in 1 pound of anthracite is 86%
10. The weight of carbon in 1 pound of anthracite is therefore 0.86 lbs.

32/12 * 0.86 lbs. of carbon = 2.2933 lbs. of oxygen needed to perfectly burn 1 lb of anthracite

2.2933 lbs. oxygen / 0.002487 lbs oxygen/gallon of air = 922 gallons of air

It takes 922 gallons of air to burn one pound of anthracite. Somewhat less if some percentage of CO is considered

If you are burning 1 lb of anthracite per hour, then it takes 922/60 = 15.4 gallons of air per minute

Someone please check my figures.
lsayre
 
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Stockton Anthracite Pea
Other Heating: Resistance Boiler (13 KW)

Re: Air Requirements for Coal Combustion

PostBy: Rigar On: Mon Sep 23, 2013 11:40 pm

DING ! DING ! DING ! DING!!!!!!
...I think we have a winner !!!!! larry :lol:

...1lb of anthracite require a little over 12 lbs of AIR for complete (theoretically) combustion
...which is about 154 CUBIC FEET
..over 60 minutes ( 1 hr) is about 2.5 cubic feet per minute (c.f.m.)

of course this is under perfect conditions..
make up air will vary alot depending on stove type ,coal quality , temperature,humidity, altitude , alignment of the stars , moon phase and shoe size....


....way to much math in this post- love it !! :D
Rigar
 
Hot Air Coal Stoker Furnace: Keystoker A 150
Coal Size/Type: anthracite rice
Stove/Furnace Make: Keystoker
Stove/Furnace Model: A 150 warm air furnace

Re: Air Requirements for Coal Combustion

PostBy: jpete On: Wed Sep 25, 2013 7:06 pm

I found this but have no idea what this is in English measurement but here it is.

http://www.brighthubengineering.com/pow ... -required/

The theoretical air required to burn the coal is

= 1.64 / 23.2% = 7.1 kg of Air for 1 kg of Coal.


EDIT: Online conversion says 7.1kg = 15.6lbs and 1kg = 2.2lbs OR pretty much what Larry said. :D
jpete
 
Hand Fed Coal Stove: Harman Mk II
Coal Size/Type: Stove, Nut, Pea
Other Heating: Dino juice

Re: Air Requirements for Coal Combustion

PostBy: WNYRob On: Wed Sep 25, 2013 9:31 pm

I don't believe anyone touched the comment Grizzly had about supplying outside air to his barometric damper. Just from reading posts from others, this is a bad idea. I don't quite remember the reasoning (something about directing outside air to the damper messes with the pressure differences between inside and out that the damper needs to work properly). But the amount of inside air you lose through the damper is insignificant.

http://nepacrossroads.com/post17443.htm ... ric#p17443
WNYRob
 
Hot Air Coal Stoker Stove: Keystoker Koker controlled with CoalTrol

Re: Air Requirements for Coal Combustion

PostBy: Rigar On: Wed Sep 25, 2013 10:31 pm

especially if its windy outdoors...can defeat the draft controlling function of the baro altogether
Rigar
 
Hot Air Coal Stoker Furnace: Keystoker A 150
Coal Size/Type: anthracite rice
Stove/Furnace Make: Keystoker
Stove/Furnace Model: A 150 warm air furnace

Re: Air Requirements for Coal Combustion

PostBy: vfw3439 On: Fri Sep 27, 2013 9:57 pm

Found some info on this topic. See attached. Look at Table 32 located on page 4 of the pdf
Attachments
OXYGEN AND AIR REQUIRED FOR COMBUSTION.pdf
Look at Table 32 located on page 4 of the pdf
(223.12 KiB) Downloaded 15 times
Select:BBcode: [nepafile=43962]OXYGEN AND AIR REQUIRED FOR COMBUSTION.pdf[/nepafile]
Last edited by vfw3439 on Fri Sep 27, 2013 10:15 pm, edited 1 time in total.
vfw3439
 
Hand Fed Coal Stove: Fuller & Warren No. 4
Baseburners & Antiques: Glenwood Base Heater No. 8, Crawford Tropic 112, Fuller & Warren No. 4
Coal Size/Type: Stove/Egg Size Anthracite Coal
Stove/Furnace Make: Glenwood Base Heater No. 8
Stove/Furnace Model: Crawford Tropic 112

Re: Air Requirements for Coal Combustion

PostBy: 2001Sierra On: Fri Sep 27, 2013 10:01 pm

vfw3439 wrote:Found some info on this topic. See attached. Look at Table 32.


Sorry you are way over my understanding :oops: And I like tech stuff, sorry :cry: Help us understand the pdf.
2001Sierra
 
Hot Air Coal Stoker Stove: Keystoker 90 Chimney vent
Coal Size/Type: Rice
Other Heating: Buderus Oil Boiler 3115-34
Stove/Furnace Model: Keystoker 90 Chimney Vent

Re: Air Requirements for Coal Combustion

PostBy: 2001Sierra On: Fri Sep 27, 2013 10:05 pm

Sorry I found the meat of your post.
CALCULATED THEORETICAL AMOUNT OF AIR REQUIRED PER POUND OF VARIOUS FUELS
Fuel
Weight of Constituents in One Pound Dry Fuel Air Required per Pound of Fuel Pounds Carbon Per Cent Hydrogen Per Cent Oxygen Per Cent Coke 94.0 … … 10.8 Anthracite Coal 91.5 3.5 2.6 11.7 Bituminous Coal 87.0 5.0 4.0 11.6 Lignite 70.0 5.0 20.0 8.9 Wood 50.0 6.0 43.5 6.0 Oil 85.0 3.0 1.0 14.3
2001Sierra
 
Hot Air Coal Stoker Stove: Keystoker 90 Chimney vent
Coal Size/Type: Rice
Other Heating: Buderus Oil Boiler 3115-34
Stove/Furnace Model: Keystoker 90 Chimney Vent

Re: Air Requirements for Coal Combustion

PostBy: Lightning On: Fri Sep 27, 2013 10:49 pm

So according to this table, one pound of Anthracite Coal needs 11.7 pounds of air for combustion..

1 cubic foot of air at standard temperature and pressure assuming average composition weighs approximately roughly 0.08 lbs. according to two sources I found..

11.7 pounds/.08 pounds per cubic ft = 146 cubic ft per one pound of coal right?

So to keep it simple lets say I burn 48 pounds in a day which is 2 pounds per hour, using 292 cubic feet of air volume per hour.

My basement is roughly 15ft x 15ft x 7ft cube = 1575 cubic feet..

SO if this is all correct then my furnace uses one full volume of the basement in combustion air every 5 and half hours..

And that doesn't count what the baro is sucking up the chimney which I would think is grossly more than combustion. :lol:
Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut/Stove Size Mix

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