BastaTim The firebox will be a coal burning gas producer to combat the efficiency problems inherited with steam locomotives.
The firebox will be a coal burning gas producer to combat the efficiency problems inherited with steam locomotives.
What say people on this forum about the effectiveness of "gas producer" coal combustion?
I read over David Wardale's Red Devil and Other Tales of the Age of Steam, and the main motivation for the GPCS (gas producer combustion system) is to reduce the carry over of carbon particles ("char" and "sparks" and "cinders") in a coal-burning lump-coal grate-fired locomotive. The idea is that if you can reduce the primary air in the coal bed, you will reduce the tendency of the fire to lift. With reduced primary air and a thick enough bed, you will get the chemical reaction to make combustible gas above the firebed, which will burn in contact with secondary air, introduced through an open fire door or through ports through the firebox.
Red Devil reads to me like a treatise in frustration of Wardale trying to get the GPCS to work up to its promise. By the end of the book, he is resigned to "pulverized coal" as being the only answer to getting complete combustion of coal fuel. But with PC (pulverized coal), you have the handling problems and explosion risk of handling PC on a locomotive, and not only that, all of the fly ash is sent up the stack. With lump-coal-on-grate, you stand a chance of at least keeping half the ash out of the atmosphere and into the ashpan.
Maybe burning coal to do anything is a lost cause, given the new EPA regs to try to take coal-fired power plants out of service. But there are a variety of combustion system besides PC that people have tried and indeed use, and GPCS is only one of them.
The one I find most intriguing is some form of "slag tap" combustion. The idea is that instead of trying to avoid the curse of clinker formation, you embrace it as a way of trapping the ash in the form that cools to a glassy rock, much easier to handle than powdery ash.
In fighting with GPCS (and his Chinese hosts), Wardale suggested that with the powdery Chinese coal and the way they were firing the QJ class, they may have been doing a kind of "slag tap" firing. Wardale speculated that the only way the crews were able to fire the coal they were getting without it all ending up out the stack is that they first wet it so it would stick together as it was pitched into the firebox, where it would stick to melted ash pooled in the firebed. In GPCS, he had to avoid slag at all cost so he wouldn't end up with a big piece of clinker filling up the firebox with the thicker firebed required. His GPCS tests were showing worse performance at very high firing rates, which was the opposite of what GPCS was supposed to do.
Wardale hints at it, he alludes to it, but he "did'nt want to go there" of using a pool of slag in the firebox as something to prevent coal loss. He worried that there was not a good way to control the amount of slag so your fire wouldn't clinker up. But if he weren't under that much time pressure, and a recurrent theme of Red Devil is that the "higher ups" had already "given up on steam" in South Africa and China when he was doing his work, given more time, he or someone could have studied what was happening in these fires to get something better.
Part of this is that he was under contract to "do GPCS" that his hosts thought was the magic solution to coal combusion and he didn't have the luxury of studying what they Chinese crews were actually doing to get the awful quality coal in China to generate any tractive effort. Maybe the way forward in China would have been to better understand what the crews were doing and improve upon it rather than conduct experiments in frustration trying to get GPCS to work with an unsuitable coal?
But again, Wardale's take is that the decision to end steam had already been made and what he accomplished, in the end, did not matter.
But post Red Devil, I see some Web sites chronicaling narrow-gauge operations claiming some success with GPCS. What do people know about this?
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
Most of you may already know this, If so, sorry for the rant...... If you watch coal burn, naturally aspirated, and correctly vented, you'll see a nice blue flame above it. This is not often seen on a steam engine unless its about to get its fire dumped. This Blue is the actually the oxygen burning up the coal AND coal gasses. The more modern steam engines use Steam, in the smoke box, to help create a "draft" in the firebox. This is why they do not need a tall smoke stack like old wood burners do. This extra "draft" makes large coal burn faster, but much less efficiently. Smaller chunks, closer together can help as it slows down combustion and still makes heat. In Western US, the Bituminous coal is already filthy and dusty and actually seems to burn up better with the extra draft . Starting a Steam engine with Anthracite and making that firebox super efficient would take at least 1 hour, then the calories it takes to boil water would make it necessary to add draft. Better draft control with emissions testing on board may help this "coal gas" and particulate "situation" . Firebox design hasnt been NOT really been gone into in half a Centry or so. Maybe a recirc Smoke gas chamber would be of interest. A guy named Paquin got a patent for this design for wood stoves ( late 70's? early 80's? )and Its been used in coal burning as well since. As most of us know, Coal is the Most powerful fuel on earth ( aside from nuclear) IT has the most calories per ton of Any fuel around 22.4 Million BTU per short ton. Burning it more efficiently in a steam engine should be looked into. That said, this current EPA is shutting down coal plants everywhere, One would think this could be overcome with some science and DESIRE.
Here are some locomotive consepts.
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