Does Damp Coal Ignite Easier or Burn Hotter

this is something I have noticed for years that overly dry dusty coal seems to take a bit longer to get going vs slightly damp coal also damp coal seems to put out more heat quicker
anybody else see this I chalked it up to the water bringing more of the volatiles/oils out of the coal
I have even taken to giving any partially burnt coal in quick bath in hotwater and it seems to make a pretty big difference in getting the partially burn stuff to re-glow

I have read that they had water injectors in coal steam engines as it was to promote hotter burning. Maybe the oxygen in the water?

maby coal does burn enough to break the bonds in H2O
would't explain why it seems to start so much better

My coal only does that if it's wet with kerosene, not water.

However, I did find this about water injected into the firebox of coal-fired steam engines.

"Firebox

In the design of a firebox, the main objective is to achieve maximum thermal efficiency. To produce enough heat to raise steam in the boiler more efficiently under the emission constraints, a new firebox with a new gas production technique is developed with 2 stages:

Stage 1:

Coal is mechanically distributed across the fuel bed, where it is burnt with little but sufficient air for complete combustion. This is meant to reduce char gasification; however, steam is injected into the furnace to produce more gases with the reduced air intake. Temperature of the burning coal is low in this manner; non combustible ashes (soot) would stay in the coal, where in the old steam locomotive it is discharged into environment. Moreover, the gas velocity is minimized ensuring fine particles of coal remain. This would greatly reduce the carbon losses; which in old engines could be over 50% at high speed. "

https://straction.wordpress.com/modern-steam/

Paul

My wife works in the kitchen at a nursing home. There's a guy that will be 101 in January, retired coal dealer. My wife has been talking with him about my burning coal. He told her to mist the coal with a spray bottle before putting it in the furnace. I haven't done it though. Dennis

You will lose the BTU needed to turn the water to steam, which will probably condense in the chimney. Bad news for a metal chimney.

I like my coal dry as a bone. I'd rather it be dusty than wet. I even made a 2 ton bin to dump my bags into to get it dryer thru the summer. Bagged coal is my only option here or I'd get bulk. I guess that explains my opinion of wet coal, but if it works for you go ahead and use it.

Limited amounts of steam in contact with glowing char (a.k.a glowing coal)/ hot carbon causes a chemical reaction that splits the water into hydrogen and carbon-monoxide(C+H2O->H2+CO)....both of which are flammable gases.....and hydrogen burns at a far higher temperature than carbon monoxide (which is the gas that normally produces the flames in an anthracite coal stove).

So your stove can output more heat for the same amount of carbon fuel....as long as you don't overdo the amount of steam being in contact with the glowing coal, if you do the temperature of the coals will fall to below the range that is needed for the water-gas shift to happen....however the amount of water contained in coal that has been kept damp/wet is not enough to cause the water gas reaction to fail but is enough for the reaction to happen.

It is best if the steam is fed in with the underfire air as you get a far better conversion rate as all the steam must pass up thru the char bed.

I know some people have a few issues understanding how this can happen as its a bit counter intuitive that water can make a fire burn hotter......however the science behind it doesn't care about that and has been used in boilers for about 100 years.

Callum

Put me into the camp of highly skeptical. The heat of evaporation seems as if it would predominate, and overall some energy would be lost. I agree with Franco B that it is also not good for the chimney if it is metal.

There maybe some confusion depending on wheather we're discussing a spray of water on top or high pressure steam being added/injected from under...very different results.
With HP Steam there would be no moisture (H2O) into chimney after water is split and the now separated parts are then combusted. But then, maybe nobody disagrees with this???

Maybe member "King Coal" can rig up a teapot for the top of his "Frankenstove
" and run a high pressure steam line down the the underside of the grates?

What is possible under proper design and operating conditions is not possible in typical coal stoves.

Throw a bucket of wet coal on the fire and the water will turn to steam with a loss of BTU long before the coal is glowing, and then condense back to water in the chimney.

The Van Wert placard I have says "Avoid using dripping wet fuel. Damp fuel is desirable. If coal becomes dry and dusty sprinkling it is recommended". That placard is probably from the 50's or 60's.

I know the old timers wanted the fuel a little damp and many of them would also want a little bit of "bone" in the coal, emphasis on a "little bit". Bone is flat stuff that has layers of rock and coal. You don't want to be burning that by itself but they felt it held the heat better. That may work for hand fired stoves but not an ideal thing for stokers.

Whether there is any truth to either I have no idea. Van Wert's recommendation is going to be built of decades of knowledge and experience and since unhippy has a scientific explanation for the dampness being desirable I'd probably have to side with that.

McGiever wrote:With HP Steam there would be no moisture (H2O) into chimney after water is split and the now separated parts are then combusted. But then, maybe nobody disagrees with this???

No matter where or how you get the hydrogen, burning it will produce water as the final product.

franco b wrote:

McGiever wrote:With HP Steam there would be no moisture (H2O) into chimney after water is split and the now separated parts are then combusted. But then, maybe nobody disagrees with this???

No matter where or how you get the hydrogen, burning it will produce water as the final product.

I know this, somehow I was blurred by the splitting parts.