Different Traction Engine Boilers

[CaseyD]

This is assignment number two for my English class: write a two-paged comparing/contrasting essay on any topic. One of the requirements my teacher did give me, however, was that the essay must be written from our existing knowledge and past experiences. Keeping that in mind, I tried many different ideas, but only the comparison and contrast between Straw burning and Wood/Coal burning boilers topic had enough to meet the criteria. Here it is, and I hope it manages to both entertain and inform!

PS--I could use some pictures of a straw burning engine - I don't happen to have any :O

Even though all high-pressure boilers simply heat water above its boiling point, there are very many different ways that the fire is used. The two most common types of boilers on steam traction engines burn either coal and wood or straw. They are similar in the way the fire itself is used, but the ways the fire is controlled and fed are different.


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A basic locomotive-type boiler, the same design used for steam tractors. Note the brick arch in the rear of the firebox.


A wood and coal burning firebox is built much simpler then a straw burner, because the fire will not be pulled up the smokestack. It is simply a small room that has cast-iron grates with slotted holes for a floor and a metal door for adding fuel and tending the fire. The door can be opened at any time, although the fire's draft will pull cold, unburnt air over the fire instead of through the fire, heating it better and more evenly.



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Here is the view of the fire that powers a coal-fed traction engine. This engine, as far as I know, has a foot pedal on the floor to enable the doors to be opened hands free, and to slam shut once the coal is scattered onto the fire.


Burning enough straw to create steam is quite difficult compared to a solid-fuel fire. Inside the straw burning firebox, there is a firebrick arch covering the flues to prevent large pieces being carried out with the smoke. The arch is a metal baffle that protrudes from the rear, bottom corner of the firebox at a 45 degree angle that has firebricks covering it. The fire door is very unique, too. Instead of just being a solid steel door, the door has a funnel-shaped chute in the middle of it that is used to force straw in continuously. With that design, the door is never really opened, it is just made up in part of the straw being pushed through it.


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A horse-drawn Case steam engine. Although this one burns wood, most early horse drawn engines like this would be able to burn straw. They were transported between threshing jobs over great lengths, so self-propulsion wouldn't have been practical. Since they were already in the field separating grain from the stalk, it makes sense that many were straw burning.


Another simple difference is the way the fuel is stored. Most coal burning engines have hoppers with slots in the bottom for easy access on the rear of the engine. Wood burning tractors can be similar, with a place to stack wood on the rear platform. If the engine is in for hard work or long travel, however, a wagon loaded with wood will be more appropriate. Straw burning tractors always need a hay wagon, though. This is because the fire needs large amounts of straw even if the engine is not being worked very hard, due to how little heat energy is in the straw. For that reason, most early steam tractors were also outfitted to be pulled by horses, even though they might have been self propelled.

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A road train setup, with both water tender and wood bunker being pulled by the tractor.


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Another traction engine with a tender behind it. This is a 1/2 scale model of a Case steam traction engine that is meant to burn coal primarily.


After the wood, coal, or straw is burnt up in its own special way, the exhaust gas from the fire is used the same way. All of it is carried through horizontal pipes that are submerged in water. The water then absorbs the heat from the fire, creating steam pressure after the water becomes hotter than it's boiling point. One special consideration in the cleaning aspect of a straw burning boiler is that glass may begin to form on the inside of the horizontal pipes, because of the high silica content in straw.


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This is the smokebox end of the flues. Fire is carried from the firebox, though them, and pushed out of the smoke stack by exhaust steam coming out of the pipe in the upper righthand corner.


After a closer analysis, it is apparent that these two different types of boilers are not very different at all: they just use a different technique to make steam. Just as each person in the world has different passions and skills, each of these boilers have their ideal applications. For example, it would not make sense to have a straw burning boiler in a sawmill, or a wood burning boiler out in the middle of the vast plains of the American Midwest. This just illustrates the long-known fact that there is no single, correct answer to any problem or question.


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This is the quote that sits above the Villuam-Corliss stationary engine out on Steamer Hill. There is an entire discussion just on this quote in the Stationary Steam Photos (http://www.wmstrcommunityforum.com/showthread.php?t=117)
thread.

[Mrs.B]

I am just checking out your new posting. Thanks for including some pictures; they help me follow the essay since I am a little steam engine illiterate! I am amazed by all that you know. By the time this class is finished, we both will have learned some things :-)

[40avery]

The truly great educator is one that is sensitive to their students and can learn as well as instruct. I am afraid there are too few that do that these days. Thank you Mrs. B:) :) :)

Rick

[CaseyD]

Here is a revision of the original essay posted above. The coal burning aspect of the original was dropped, because the meaning was ambiguous at times. Enjoy! (If you have not read the original, take a look at the pictures in it to go with the story)

CaseyD



Straw burning and Wood burning
Steam boilers have been labeled as dangerous and inefficient since the advent of gasoline engines. In reality, there have been no boiler explosions in Minnesota for over 100 years. Although antique boilers are only 3% thermally efficient, they are true hybrid, multi-fuel engines. The two most common fuels for boilers on steam traction engines are wood and straw. Straw burning boilers have a unique construction that allows them to burn the fluffy, light straw. Wood burning boilers are different in the ways the fire is controlled and fed, although identical in the way the fire itself is used. Lastly, their applications and fuel storage differ accordingly.
A wood burning fireboxes are built much simpler than that of a straw burner because the fire will not be pulled up the smokestack with the draft. It is simply a small room that has cast-iron grates with slotted holes for a floor and a metal door for adding fuel and tending the fire. The door can be opened for inspection or stoking at any time, although the fire's draft will pull cold, unheated air over the fire instead of through the fire. This can be destructive to the rear wall of the firebox because the cold air will make the metal contract, causing leaks and weakness. Wood burning boilers are better suited to either an area where wood is convenient, like a sawmill; or boilers that do not have much fuel storage available, like a steam locomotive or steamboat.
Burning enough straw to create steam is quite difficult compared to a solid-fuel fire. Inside the straw burning firebox, there is a firebrick arch covering the flues to prevent large pieces being carried out with the smoke. The arch is a metal baffle that protrudes from the rear, bottom corner of the firebox at a 45 degree angle that is covered with firebricks. The fire door is very unique too: instead of just being a solid steel door, the door has a funnel-shaped chute going through the middle to force straw inward continuously. With this design, the door is never really opened; the chute in the door is packed with straw as it is fed into the fire.
After the wood and straw is burnt up in its own special way, the exhaust gas from the fire is used the same way. All of it is carried through horizontal pipes submerged in water. The water then absorbs the heat from the fire, creating steam pressure after the water ia heated beyond its boiling point. One special consideration in the cleaning aspect of a straw burning boiler is that glass may begin to form on the inside of the horizontal pipes, because of the high silica content in straw.
Another simple difference is the way the fuel is stored. Wood burning tractors have a place to stack wood on the rear platform. If the engine is in for hard work or long travel, however, a wagon loaded with wood will be more appropriate. Finding fuel for wood burning boilers is a drawback in areas like the vast plains of the American Midwest, or long distance seafaring boats. Straw burning tractors always need a hay wagon, though. This is because the fire needs large amounts of straw even if the engine is not being worked very hard, due to the straw's little heat energy. Since the straw fire requires large volumes of fuel, it is very impractical for a locomotion or marine engine. Likewise, most early straw burning tractors were also outfitted to be pulled by horses, even though they might have been self propelled.
Even though both types of boilers do the same job, they just use a different technique to make steam. Both types use fire, of course, but the way the fire is fed and controlled is different. With the fire's different needs, the way the fuel is stored is also unique. This can be drawn parallel to people: just as each person in the world has different passions and skills, each of these boilers have their ideal applications. Realizing these personal traits helps people understand each other and find a place where their skills and interests are important to the community.

[40avery]

Casey,

Here is a picture of a straw burner. This engine is still running and threshes and saws every year at New Rockford. The original owner ordered and used this engine as a straw burner for a number of years and then converted it to a coal burner. It is a very sweet engine to run and fire.

Rick