BTU''S in a Pound of 100% Pure Carbon

McGiever wrote:

lsayre wrote:If heating your home with coal gives you a smaller carbon dioxide footprint than doing the same with electricity, why isn't the government banning all-electric homes?

Not all electrity is directly tied to carbon based (fossil) fuel...and there is a lot invested in infastructure too. And the future of electricity is to be fueled by less and less fossil fuel.

Need I mention...erhmm... utility stockholders?

We're on hydro here, from the St Lawrence seaway hydro plants, with gas supplement when the demand goes over the contract KW allotment.

Plus, once you get north of Troy, there are lots of dams and small hydro power plants along the upper Hudson River, going well up into the Adirondacks.
NY is one of the biggest for hydro power,..... and has been going back about 100 years.
http://www.dec.ny.gov/energy/43242.html

Plus four nuclear power plants.

Not so many coal-fired plants.
https://en.wikipedia.org/wiki/List_of_power_stations_in_New_York

Plus

More interesting info:

Vaporizing a pound of water consumes 1,050 BTU's.

Sulphur contributes about 4000 Btu/lb, from the reaction: S + O2 → SO2

The Dulong equation for BTU's is Btu/lb = 145.5C + 620(H - O/8) + 41S
The letters represent the percentages in the ultimate analysis, and C is the percent carbon in a solid fuel. H is hydrogen, O is oxygen, S is sulfur.

Coke has a heating value of approximately 13,000 Btu/lb . A typical foundry coke might be 90.5% fixed carbon, 8.64% ash, with typically less than 1% volatiles.

1 BTU = 252 calories. (Note: What we call food calories are actually kilo-calories. 1 BTU = 0.252 food calories).

Lots of good information here:

http://www.sgs.com/en/mining/analytical-services/coal-and-coke/coal-calculations

And here:

https://en.wikipedia.org/wiki/Energy_value_of_coal

franco b wrote:I don't think the ash is acidic at all. The ash pan has zero rust. the steel chimney rots from the top down where condensation takes place the most.

Wood has even more condensation but does not seem to rot , and even protects the pipe.

Might be your ash pan has less moisture attracted to it than some other folks, cause I seen on occasion some ash pans that were riddled with jumbo pit holes throughout. The acid could be there, just that it fly-ash is too dry to become reactive with the iron.
Top down still fits this profile...ask some peeps with damp basements reaching condensing temperatures.

No moisture no acid...or better yet...acid is proportional to moisture.

I discovered some detailed research that took about 5 different methods of computing the "as delivered" BTU's in a pound of coal (including Dulong's Equation) and regressed them all into one tidy equation which when tested proved to be more accurate than any of the original equations. It seems a bit odd that it includes ash %, but it is probably the best equation for calculating "as delivered" BTU's out there.

Here it is:

BTU's = 198.11*C%+ 620.31*H% + 80.93*S% + 44.95*A% - 5153

And here is the link to where I found this:

https://web.anl.gov/PCS/acsfuel/preprint%20archive/Files/25_3_SAN%20FRANCISCO_08-80_0235.pdf

I don't know yet how to come up with a good means to determine an average value for the percentage of hydrogen present within the volatiles component, so for now I'm doing just as I did before and summing the % volatiles and % carbon and calling it all carbon just as I did earlier in this thread. And then I'm dropping the hydrogen part of the equation out of the equation.

The empirically modified equation as I'm currently using it then becomes:

BTU's = 198.11*(C% +V%) + 80.93*S% + 44.95*A% - 5153

Example using the data that Lightning recently provided in a different thread:
% Carbon 82.04
% Sulphur 0.61
% Ash 9.34
% Volatile Matter 3.71
% Moisture 5.92

BTU's = 198.11 x (82.04 + 3.71) + 80.93 x 0.61 + 44.95 x 9.34 - 5153
BTU's = 12,304

And lastly, in one pound of this coal there are 0.0592 lbs of water which we must vaporize, so:
0.0592 x 1,050 = 62 BTU's to vaporize the water

The final answer for Lightning's anthracite then becomes:
12,304 - 62 = 12,242 BTU's per pound (as delivered)

Attached here I have placed the above formula for calculating the BTU's in 'as delivered' anthracite into an easy to use spreadsheet. It may also work well for semi-anthracite, bituminous, sub-bituminous, and lignite (though I have not tested this).

NOTE: All user input values must be for "as delivered" coal. Values must not be entered on a "DB" (dry basis). If you can only find information listed as DB, then find the % water, subtract it from 100%, then divide your answer by 100, and then multiply this fraction across the board for all of the DB listed values. That should convert them to AR (as received).

As always, kick the tires and let me know if it works for you.

I'm making an initial estimate that the average hydrogen in typical coal/wood volatiles represents about 16% of the volatile component by weight, since data I saw ranged from 13% to 19%.

The regressed BTU equation from the source referenced above:
BTU's/lb. = 198.11*C%+ 620.31*H% + 80.93*S% + 44.95*A% - 5153

Can be thus modified empirically to read:

BTU's/lb. = 198.11*C%+ 620.31*(V%*0.16) + 80.93*S% + 44.95*A% - 5153

And then lastly you must vaporize the water and account for BTU losses therein.

This revision to the equation allows you to use the volatiles percentage (V%) as given for your as delivered anthracite, and not concern yourself with the hydrogen component (since you are accounting for it as 16% of the Volatiles). This may be the best I can do to come up with a simple yet respectably accurate "as delivered" BTU equation for coal. It should work for all types of coal and even for wood.

Perhaps the most interesting thing I have taken from this is that there are not as many BTU's in volatiles as there are in carbon, on a pound for pound, or percent by weight for percent by weight basis. So if you are being told that higher volatiles mean more BTU's you are being told a lie. Higher carbon and lower volatiles means higher overall as delivered BTU's. So much for my initial assumption of equivalence.

I saw some data which indicated the percent carbon in kiln dried hardwood is typically 48%. And kiln dried softwood typically has about 51% carbon. Kiln dried wood also has typically about 37% Volatiles, 8% water, and 1% Ash.

If 8% moisture, 48% carbon, 37% Volatiles, and 1% ash are assumed, when I plug these figures into my revised spreadsheet I get 7,989 BTU's per pound, which is a match to the 8,000 BTU/lb. figure often quoted for premium hardwood pellets. Softwood pellets yield 8,584 BTU's/lb., and mixed pellets would result with ~8,300 BTU's/lb.

Multiply C and V and Ash as listed above for pellets by 0.88 and then bump water up to 20% to simulate well seasoned cut and stacked hardwood and you get 6,240 BTU's/lb., which is again quite close to the accepted value for ideally seasoned mixed hardwoods. Multiply by 0.78 and bump water to 30% and you have 4,817 BTU's/lb.

If there is interest, I will post my revised version of the spreadsheet.

It should be said at this juncture that the various BTU "math models" (including here Dulong and all of the rest) are merely empirical attempts to mimic what is most accurately to be measured in a device called a calorimeter.

Per my linked source, the new math model that this source regressed from a combination of all of the other math models came closest overall to mimicking reality in more cases than the others did, but my guess is that many to most of the coal mines are still using Dulong.

Some of the larger mines may do in house bomb calorimeter testing. Others can periodically send out samples to be calorimeter tested via outside labs.