% Unburned

coaledsweat wrote:According to Axeman-Anderson, a ton of anthracite starts with 240# of useless ash (12%). The anthratube will waste 60# of that ton in unburned coal (3%). It also points out that 200# (10%) goes up the chimney as wasted heat. That leaves 1500# actually heating the house (75%). I would think that other stokers would be a little less efficient. That adds up to about 15% or 15 # per hundred in to ash out w/unburned coal as the "best case" scenario.

I will add that the "Yanche Report" (Bureau of mines) shows it to be slightly more efficient than advertised.

So unburned % in the very best case will run 3% or higher, the average stoker may run @ 4-6% (4-6#) unburned coal in the ash.

:bsod: OK, I take back all the complimentary things I said about admin! Here's what I can recollect about the massive deleted portion of my earlier post:

First, referring to the above quote, I posited the question whether I reasonably may infer that, if I'm running at about a 20% weight ratio of ash-to-fuel, I may consider that a pretty reasonable fuel consumption efficiency, even if my ash looks like it contains a fair amount of unburnt coal. (The ash number is a guess; I weigh my fuel in but not my ash out.)

Then I admitted that, at the beginning of the season, I tried to strain out the unburnt fuel from the ash. But not for long!

* * * * * * *

Finally, I waxed along a season-ending theme of the value of this forum in pooling and preserving a body of experience and expertise on the subject of coal heating, which it is my impression was in danger of practical extinction. I've found it interesting that old-timers often show what seems to be instinctual familiarity with the parameters and rhythms of coal burning, probably owing to having grown up with coal furnaces. Yet it seems largely lost on the boomer generation, where more "convenient" fuels have been nearly universal. So here we're trying to collect and preserve what we can of what's gone before, in addition to adding what we can of what new technology can bring to both the efficiency and user-friendliness of coal heating.

Then I thanked the forum administration for providing a place to do all this.

And now I've retracted all that. :footballhelmet:

Yanche wrote:

stockingfull wrote:Even if my brother thinks I'm now responsible for global warming! :roll

It's not clear to me how much residential coal heating contributes to global warming compared to the other alternatives. For example over half of the US electricity is produced by burning bituminous coal. It's not a very efficient OVERALL process to turn back into heat. I'm trying to understand all the losses in making that electricity and getting it to the user. Looks like 1/3 of the energy in the coal is lost, lost heat at the power plant, transmission losses in the electric power grid, etc. Residential coal heat is a low temperature process. We are not making high pressure steam to drive a turbine. A much greater fraction on the energy in the coal gets used. It may turn out that from a global warming point of view, local residential Anthracite coal burning in an efficient boiler is desirable. I welcome analysis by others. This is an scientific analysis task the Anthracite producers and appliance manufacturers should jump on. Like I say, "Coal, back to the Future"

Yanche

I have always understood that the production of electricity uses 1/3 of the input thermal energy and that 2/3 is lost. To put it another way, recognizing that one kilowatt of electricity will produce 3400 BTU if it is used for resistive heating, then it takes more than 10,000 BTU thermal input at the power plant to get one kilowatt to the consumer.

By comparison, an efficient boiler will put about 8000 BTU of every 10,000 BTU (80%) input into the home. Of course in figuring total efficiency you also have to take into account any electricity input to run the blower and stoker in a boiler like the AHS-130.

stockingfull wrote::bsod: OK, I take back all the complimentary things I said about admin! Here's what I can recollect about the massive deleted portion of my earlier post:

Ironic that your compliments were the only thing left , maybe it was my subconscious egotistical side that did it. I've done that before but I always catch myself doing it before I hit the submit button, at least as far as I know that's the first time that has happened. Sorry again.

Edit: Next time I'll just blame it on Greg.

OK, back on topic for a moment:

I weighed 2 bins of ash last night, one 45#, the other 42#, net of course.

The 42# was the proceeds from fuel input of 250#, as nearly as I can estimate. (This is interpolation because I removed the ash in the afternoon but load around 11PM.) So my honest injun ash yield on that run was 16.8% by weight.

Based on the analysis above, I'm figuring that's not bad, even though the ash doesn't "look" that good (i.e., a mix of clinker, powder and seemingly unburnt bits).

I always thought that the rule of thumb is 1lb of coal = 1kw/h of electricity.

If you go by the spreadsheet linked to here you need about 7300 kWh to equal 1 ton of coal, 2000 pounds to a ton so you have approximately 3.7 pounds to 1 kWh ratio.

Edit: note I haven't adjusted for efficiency.

Using 13,000 BTU per pound for coal and 3400 BTU per KWH, its more like 3.8 KWH per pound of coal. I know that you never get all the heat content from burning any fossil fuel, but using 70% as an overall efficiency for coal, it would still take 2.67 KWH to equal the heat content of 1Lb of coal.

Using my rate of .11$ per KWh, and $170 / Ton , it works out to about 30 cents worth of electricity to equal 8.5 cents worth of coal.

I just got another of those 'math headaches'

However it works out, I'd rather pay a few hard working people in the coal industry instead of a huge business [electric, gas, propane, or oil] with hundreds or thousands of executives sitting at desks in front of computers trying to justify their salary.

I can tell the folks in the coal industry have earned their income from the dirt on their clothes, and coal dust under their fingernails.

Greg L

To produce one Watt of electricity, it takes 1.0 lbs. of coal/kWh from coal plants using steam turbines, 0.48 lbs. of natural gas from natural gas using steam turbines, 0.37 lbs. of natural gas/kWh using combined cycle technology, 0.58 lbs. of Heavy Oil/kWh using steam turbines, and .0000008 lbs. of Uranium enriched at 4% U235 and 96% U238 for use in a commercial nuclear reactor.

All this puts you in "migraine territory".

My local electric supplier's coal fired plant (Brandon Shores, MD) is a slightly more efficient. It produces 642 megawatts while burning 250 tons/hour of KY and VW coal. Which works out to 0.769 lbs of coal per watt. Now if I compare using that electricity to heat my home vs. my Anthracite coal boiler I find my home boiler produces less global warming CO2 emissions. Let's go environmentalists, embrace residential coal central heating and save human life on earth!

Yanche

If you want coal to stay a viable home heating source then you need to keep the enviromentalists out of it. Things have a way of going to crap when they get involved.

NEW SPECIES FOUND!
Anthropoligists found in and around eastern Pennsyvania a new species of man that appears to be an offshoot of the Homo Sapiens. Named Homo Anthracitus, the new creature appears to be very adept at keeping warm at reasonable prices. Scientists note that the creature's brain can function at a much higher level than it's predecessor's.

NEW SPECIES FOUND: continued

Yet despite their advanced intellectaul abilities, they have yet to devise a method for emptying the ash pan without making a mess!

gambler wrote:If you want coal to stay a viable home heating source then you need to keep the enviromentalists out of it. Things have a way of going to crap when they get involved.

This brings to mind a comment made by Dr. George Reisman:
*****************************************
Perhaps of great significance is the continuous and profound distrust of science and technology that the environmental movement displays.

The environmental movement maintains that science and technology cannot be relied upon to build a safe atomic power plant, to produce a pesticide that is safe, or even bake a loaf of bread that is safe, if that loaf of bread contains chemical preservatives.

When it comes to global warming, however, it turns out that there is one area in which the environmental movement displays the most breathtaking confidence in the reliability of science and technology, an area in which, until recently, no one — even the staunchest supporters of science and technology — had ever thought to assert very much confidence at all. The one thing, the environmental movement holds, that science and technology can do so well that we are entitled to have unlimited confidence in them, is forecast the weather! — for the next one
hundred years......
*******************************************

If you want coal to stay a viable home heating source then you need to keep the enviromentalists out of it. Things have a way of going to crap when they get involved.

I hate for my first post to start an argument from a 9 month-old post... but it is.
I'm going to have to disagree a little with you, gambler. I had a professor in one of my college wildlife science classes remind us that it is always more efficient to get heat from a primary source, rather than to convert it to electricity, transport the electricity, then convert it back to heat. Made a lot of sense to me, but I didn't understand why he was telling us this. I thought all houses had natural gas piped in like water and you just burned that. Then again, that was in TX and we burned heat a few days a year. Or when it got down to 55 if my mom had her way.

I just clipped a long story I was typing. I'll save that for another thread.

My point is, I am learning how to burn coal because a) there was a Harman in the garage when we bought the house and b) It's still more energy efficient to make my own heat than pipe it in. It doesn't make sense for me to go on a tear replacing all the light bulbs in the house with compact fluorescents and then HEAT with electricity. My card-carrying-green-party-member-environmental-ed-teacher conscience won't let me get away with it.

On topic: it seems to my like there is a little ash mixed in with clumps of lighter gray coal when I'm done. Then again, I don't have a thermostat hooked up to it (It's just jumpered on) and I have no idea what I'm doing.... yet.

Now, I promised my wife I wouldn't burn the house down, so please excuse me.
pb