Coal BTU

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Ronnie
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Post by Ronnie » Thu. Mar. 25, 2021 9:13 am

I was shopping for next years coal. Checking stated BTU's and price. Called American, they said 11000 to 12000 at 150 a ton. Called Lehigh, the salesman said 17000 at 180 a ton.

My question is does Lehigh coal really produce 17000 BTU's per pound?


 
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Post by McGiever » Thu. Mar. 25, 2021 9:22 am

Guess you could ask for copy of each ones recent analysis report...
Last edited by McGiever on Thu. Mar. 25, 2021 9:47 am, edited 3 times in total.

 
Ronnie
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Post by Ronnie » Thu. Mar. 25, 2021 9:30 am

When I said American, I am speaking of American Premium Coal in Tamaqua Pa.

 
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lsayre
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Post by lsayre » Thu. Mar. 25, 2021 9:50 am

17,000 BTU's per pound must be the laboratory figure for coal that is purified, and then reported as "dry and ash free".

Add in ~5% inherent 'internal' moisture, and you are already down 5%. Then add in the heat required in order to evaporate and free the coal of this inherent and internal moisture and you are down even more.

Then add back in the ~14% - 15% ash, and you are down even more. Plus ash absorbs heat, and is a great insulator.

If asked, my guess is that Lehigh will likely tell you that on strictly an "As Delivered" basis you can "nominally" (as opposed to cherry picking the data) expect good quality anthracite to have roughly an "input" valuation at about 12,250 BTU's per pound.

And 'overall' you will loose about 30% of that in the act of burning it in a stove. And in this I care less if the stoves manufacturer claims 90% or better efficiency. What matters is the "real world", and carefully 'staged' tests are simply not representative of the real world.

So call it roughly 8,600 'usable' (as in deliverable) BTU's per pound.

But be aware that homes are generally found to require far less BTU's than typically imagined or presumed via intuition whereby to sufficiently heat them. Intuition almost always makes for bad science.

In my opinion, American was the more honest party here.

 
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lsayre
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Post by lsayre » Thu. Mar. 25, 2021 10:16 am

One gram of pure carbon burning straight to pure carbon dioxide in a 100% efficient reaction evolves 8,080 gram-calories of heat.

There are 453.6 grams in one pound.

There are 252 calories in one BTU.

Therefore: There are 8,080 x 453.6/252 = 14,544 BTU's in one pound of 100% pure carbon.

 
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lsayre
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Post by lsayre » Thu. Mar. 25, 2021 10:30 am

If the nominal volatiles in anthracite are at 3.50% by weight, and if the volatiles are pure natural gas, then there are 0.0375 pounds of natural gas entrapped within a pound of anthracite.

Natural gas has ~112,000 BTU's per compressed NG pound.

112,000 x 0.035 ~= 3,920 "maximum *" extra BTU's per pound of coal due to entrapped NG.

* The natural gas in coal is not likely going to be found to be 100% compressed into the liquid state, so actual BTU's will likely be less than this.

 
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lsayre
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Post by lsayre » Thu. Mar. 25, 2021 10:41 am

So if you had what was initially 100% pure carbon and impregnated it with 3.5% by weight natural gas the maximum BTU's would be around 18,500 per pound. But anthracite is only around 82%-86% carbon...


 
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Post by freetown fred » Thu. Mar. 25, 2021 2:03 pm

Good Lord R--see what ya started!! LOL

 
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Post by Ronnie » Thu. Mar. 25, 2021 2:08 pm

Thank you for the info, I knew my handbook didn't show any numbers like that.

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lsayre
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Post by lsayre » Thu. Mar. 25, 2021 2:19 pm

I wonder why the trend is to exclusively report the HHV (high heat value) when for every HHV there should in fairness be a corresponding LHV, and then an average between HHV and LHV? Why are the LHV 'samples' data missing? This hearkens to my comment above regarding "Cherry Picking the data". And did anyone beside me note that the disclaimer for the data in the image above is that these values are for "samples" and not for delivered (as in "As Delivered") coal?

As an aside I believe it was Berlin who taught us that good bituminous can often have more BTU's per pound than good anthracite. Likely due to more volatiles. And it can have less ash also. But be hard to control.

 
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Post by Rob R. » Thu. Mar. 25, 2021 2:34 pm

There is only one thing to do. Buy some of both and tell us which one burns hotter.

 
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Post by warminmn » Thu. Mar. 25, 2021 4:42 pm

Thats too simple Rob! :lol:

It could change from load to load also. Or if burning TSC coal, from bag to bag. Blaschak may be the most consistent as they mix coal together. Maybe others do that too, I dont know.

 
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Post by BigBarney » Sun. Mar. 28, 2021 5:34 pm

There is no coal anywhere on earth that has 17,000 btu/# , the very best is about

`>15,000 and that is a very small select example.

Bituminous will have more btu's because many of the hundreds of compounds

have higher btu's than pure carbon. Coal gas from a power plant has about

16,500 btu / # so that is near the theoretical maximum of coal. There are many other

gases in bituminous coal gas but in very minute amounts so add very little to

the overall heat produced.

Good coal of any type has ~10-15% ash so the heat can only be 85-90% of the

pure value of the sample.

A few samples have less than 5% ash and yield these higher outputs ,and have

many long chain hydrocarbons which boost the energy ,but you have to be able

to burn these compounds to realize the full output. Many of these are in the

smoke which is wasted energy.

BigBarney

 
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Post by Hoytman » Sat. Apr. 10, 2021 2:09 pm

lsayre wrote:
Thu. Mar. 25, 2021 2:19 pm
Likely due to more volatiles. And it can have less ash also.
If I take this statement out of context it would illustrate the difference that I found between one brand of coal that. Burn and TSC...and it would describe the TSC coal I burned even though it was dirtier and a mixture of sizes. Lots of volatiles and heat with little ash.

 
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Post by Richard S. » Sat. Apr. 10, 2021 11:21 pm

lsayre wrote:
Thu. Mar. 25, 2021 10:41 am
So if you had what was initially 100% pure carbon and impregnated it with 3.5% by weight natural gas the maximum BTU's would be around 18,500 per pound. But anthracite is only around 82%-86% carbon...
One thing to be aware of is Lehigh is mining the Mammoth vein which has significantly lower ash content than average. I believe Blaschak is in that vein too. I know at one point when I was delivering and the breaker was sourcing from that vein the loader operator commented he was testing it at 5 or 6% ash. Average he was getting from the other coal they were processing was 12ish. That coal is like glass, you can even hear the difference when it goes down the chute. You can shatter it and get pieces as sharp as razors if they flake off right. It's also very dense, guesstimate is about 10% less volume compared to average coal.

Note it's possible the consumer may not be getting that full product because it sometimes gets mixed with lower grade product. In fact if you have stoker it can be problematic to burn.... That same year I was getting complaints from some customers with smaller stokers, try explaining to a customer the problem is the quality is too high. ;) The hand fire operators on the other hand loved it.


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