I'm a little confused here, MK.

Oil firing can appear clean, but there are residual heavy metals in recycled oils which will be emitted, whether visibly or not.

Converting to a fuel which produces nastier invisible stuff doesn't mean less environmental damage than one that produces visible but more innocous stuff. Much of the particulate matter in coal locomotive smoke is just stuff that was dug out of the earth heading up on heat convection before going back to where it came from - unburnt fuel.

Unless the issue here isn't environmental concerns but rather making smoke invisible? Is this really just a cosmetic problem? What you can't see can't hurt you? If so, please present it honestly as such rather than a true environmental or health issue.

Besides, I haven't seen any burden of proof imposed to prove that occasional exposure to locomotive coal smoke causes any health problems, compared to, say, the exhausts from a few hundred SUVs. Will you eliminate them next please?

Overfire jets help burn coal more completely by introducing a secondary source of combustion air into the mixture of gasses and particulates over the firebed. A more refined coal bed design that does a better job of it - without using overfire jets - is the Gas Producer Combustion System which has been very successfully fitted to locomotives. No need to reinvent the wheel, just make one the right size for this application.

Cleaner coal burned more completely could solve the cosmetic problem by making the smoke more invisible, if that is the actual goal.

Some very clean and efficient oil firing systems have been designed and proven, most notably by Waller in the new generation of SLM rack engines which debuted about 15 years ago. Their system uses light oil - much like diesel or kerosene - the variability of quality in the waste recycled oil fuel mixtures can't be fine tuned in such a system, nor in Nigel Day's impressive new burners. Reliability of supply quality pretty much throws modern oil firing systems out of consideration for waste oil.

There's less hardwood than coal or oil near Four Corners. Both oil and coal contain more BTUs per volume mass than wood, so wood probably isn't a reasonable solution. D&SNG has coal handling capabilities, but nothing in terms of infrastructure for wood or oil. Locomotives are just one part of the overall system.

dave

I agree that the state will soon take action. Nobody, including the state, wants to kill the golden goose. However, it is my belief that almost any level of government is quite capable of killing a golden goose even though they intend not to. They have announced the deadly toxins present in coal smoke, and have gone on record as "having the hammer" regarding the authority over D&S emissions. Any day they could surprise us all.

What would be the cost of converting a D&S locomotive from a coal burner to an oil burner?

Ron Travis Keagle

I have looked as some diagrams and descriptions of the recent technological improvements such as the low backpressure exhaust nozzles and the gas producer firebox. As I understand it, the improved nozzles will increase operating efficiency, but do nothing to curtail smoke during overnight firing. Some have stated that the gas-producing firebox will curtail overnight smoke, but I do not entirely understand how this firebox works and how it would affect the performance of a banked fire.

As I understand it, the GP firebox has a fire bed that is deeper than the fire bed in a conventional firebox, and has a field of steam jets below the grates that blow upward, through the grates, and into the fire bed. It also has inlets for secondary combustion air to enter through the top to the boiler and crown sheet, and pass into the top of the firebox.

What is the purpose of blowing steam up through the fire bed? Does the steam pass through a cone tube in order to pick up air and force it into the fire bed? In other words, is the steam just a means to pump air into the fire?

Is it only the nozzle / stack draft suction that forces air to enter the top opening for the secondary combustion air? If not, what is the power source to inject the secondary air?

Does the secondary air merely pass straight through a single port, from outside of the boiler to the interior of the firebox, or is there a multi-port manifold to distribute the secondary air broadly inside of the firebox?

How would these features reduce smoke from a banked fire?

Ron Travis Keagle

If conversion to oil is to take place then I would think that a sub contractor experienced with this would be brought in. I am sure that there are a few around but one name that is very good is Nigel Day. I am sure that there will be agreement as to his credentials

Mr. Mizer:

I have sent you a PM regarding this posting.

sc 'doc' lewis

Ron - please check out Hugh Odom's ULTIMATE STEAM PAGE for better explainations than I could ever provide.

The steam beneath the grate is not a blower to force draft as we understand it.

The firebed is most efficient at a depth of "13 particles", which I take to mean thirteen lumps of coal.

Porta developed the technology watching locomotives in Latin America maintaining steam and clean stacks with the firedoor open.

The basic premise is creating a coke plant in the locomotive firebox, then burning the coke.

dave

And Mr. SC Doc, One right back at ya.

The purpose of mixing steam with primary air is twofold. The main purpose is to keep the temperature of the firebed below the ash fusion temperature of the coal. This counteracts a thick fire's tendency to clinker. The second beneficial effect is that the steam reacts with the carbon in the coal to form carbon monoxide gas, which is then burned (oxidized) above the firebed in secondary air.

It is possible to use only the smokebox vacuum to supply secondary air to the fire. However, Wardale additionally used overfire jets, claiming the turbulence lead to better air/producer gas mixing and, therefore, more complete combustion.

Secondary air reaches the fire through a variety of overfire tubes. The overfire tubes are located on the sidesheets, crown sheet, and door sheet. Also, Wardale used the firedoor to supply additional secondary air.

The main benefit of GPCS is a more stable firebed, since most of the combustion air is secondary air. It prevents coal "carry over," i.e. unburned coal particles being sucked off the grate and out the stack before they have a chance to burn completely. As carry over only occurs in perceptible quantities when the engine is working, you derive most of the benefit only when the engine is running. GPCS equipped engines are reported as smoking less on standby than conventional engines, but I would attribute that to the overfire tubes and/or jets required by GPCS, and not to the use of a producer gas system per se.
-Chris

Chris,
Thanks for the information on the GPCS.

I understand generally what banking a fire means, but I have some questions about the procedure. Does the fire banking process denote a consistent, specific process, or are there different degrees of banking related to different levels of desired heat production? Assuming that pressure drops after a fire is banked, is coal added periodically to maintain the pressure at some reduced level, or is the pressure allowed to continue to drop until morning with no coal being added?

Can a coal fire be idle or banked for a prolonged time without making significant smoke like when a wood fire goes into the third stage of combustion and burns pure carbon with no volatiles being released?

RTK

I wish I had Chris' felicity for explaining complex technical stuff so succinctly. Probably the result of his more formal education. When I learned chemistry, there were only 4 elements to worry about, and writing about this stuff always brings diverting anecdotes to mind, such as........oh, well, off again. Sorry.

I think the benefit derived from GPCS for this specific set of circumstances is that the firebed would be clean and deep when the train arrives back in Durango, and composed of basically coke, the gaseous byproducts having been driven off and burned.

Shaking out the ashes will then leave a lot more coke on the grates, so adding a smaller quantity of "clean smokless coal'", which could be lifted to the gangway in a skip on a forklift or in a front end loader bucket, would provide a nice bank without having to create a seperate clean coal bunker in the tender.

Side benefit is a cleaner railroad all the way up and down the line, and if Lempor or Lemporkoop is also installed, much less coal burned with a higher power output.

Whether this higher power output is adequate to allow for an additional coach to be pulled to either increase revenue, or decrease expenses by dividing one train into additional bits of all the others, remains to be calculated.

On the other hand, might it be possible to have a clean bank built of coked coal, thanks to GPCS, already in the firebox when the train arrives back at the bottom of the hill?

So many interesting possibilities, and on one of the few tourist railroads operated intensively enough to truly benefit from the investment in modern technology.

dave

Ron,
Yes, banking is a specific process. When an engine is brought in at the end of a trip, a "heel" of coal is built across the back of the grates up almost level with the fire door. The rest of the fire is allowed to go out, and the stack is capped to keep the natural draft from sucking cold air through your warm firebox. This coal cokes over and smolders all night. No coal need be added if the layover is shorter than about twelve hours. The pressure is allowed to drop, but assuming that your engine is tight (no leaking stays or valves), you'll still have in the neighborhood of half of operating pressure in the morning (this depends on a number of variables). The purpose of banking is mainly to keep the firebox sheets warm and to allow the engine to be fired up more easily. To ready the engine for service, you "break the bank," scattering the banked coal over the grates. Now exposed to oxygen, the smoldering coal bursts into flames. You throw in a couple of scoops of coal, and voila, you have a nice standby fire. An engine that is banked and capped won't produce much smoke. Burning Pocahontas coal, the engines didn't smoke too badly even during bank breaking and firing up. Except when I was on the engine. Then, according to my co-workers, it was James Bond smokescreen time because I was a stupid rookie. I'm now in the tree hugging, oil firing hippie region of the country, but amazingly enough I can still produce a 007 smokescreen and am still, to hear my co-workers talk, a stupid rookie. Hope this helps.
Stay Safe,
Chris Zahrt

Dave,
I can see your point about how a GPCS could provide a kind of indirect benefit to overnight idling by creating a deep bed of what amounts to coke, which could then be used as the clean overnight fuel.

Chris,
Thanks for the banking explanation, but it leads me to another question. The overnight idling of D&S engines has been frequently referred to as “hot standby.” I understand that most of the smoke complaints result from smoke produced during this overnight phase, and I have read that they do add coal periodically during this hot standby period. I have never heard whether the overnight smoke is only produced when they add coal, or if it is generally produced continuously during the night. Would it be correct to say that this so-called hot standby on the D&S is not a banked fire?

Does hot standby amount to maintaining a fire that is somewhere in between a banked fire and one that is at full power? If that is the case, then hot standby uses more coal than a banked fire. So, with that disadvantage, why would hot standby be preferred over banking? Is the excess coal consumption overnight offset by the ability to bring the boiler and fire up to full power quicker in the morning?

If this is true, then it would follow that hot standby would produce more smoke than a banked fire overnight, but less smoke than a banked fire during startup. Which of the two techniques would produce the least smoke during the entire layover, including the startup?

RTK

Ron-
I'm not at all familiar with the D&S's operation, so I'm just guessing here. Hot standby to me means they're keeping a full fire on the grates, but not a "road fire." The best way hot standby was explained to me was thinking of the engine as a giant crock pot, and you just want to keep her simmering. So yes, hot standby is not a banked fire. I read in one of these threads that they coal, water and service the engines at night. If so, then you're moving the engine around at night, and you wouldn't want a banked fire. With a bank, you don't have fire over the entire grate. If you moved the engine, you'd suck a lot of cold air through the boiler, causing the stays and tubes to leak. Also, you wouldn't be able to maintain pressure, and large, rapid changes in pressure are hard on a boiler. I'd say that hot standby would produce more overall smoke, but banking would produce more smoke when its least wanted (6-8 am). However, if they're moving engines around at night, then banking isn't really an option.
Stay Safe,
Chris Zahrt
Arizona Steam Mafia

Chris,

You're right that a Lempor won't really do anything for an engine during layover (except that the improved blower design should reduce coal consumption on a stationary engine). I do believe a Lempor can help minimize smoke during initial moves of an engine with a "green" fire, especially on engines with the GPCS, by ensuring ample combustion air for the fire.

Thanks for your insight on hot standby Chris. I can see how this would make smoke. Such a low power, volatile producing fire would make a technological solution difficult.

RTK