Читать книгу Young Engineer's Guide - J. V. Rohan - Страница 12

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concerning the operation and care of steam boilers.

Q. How is steam taken from the boiler?

A. By suitable piping leading from a steam dome on top of boiler.

Q. What is a steam dome and how is it made?

A. A steam dome is cylindrical in shape, is made usually of boiler plate flanged and riveted over a hole on top of boiler.

Q. Of what use is a steam dome?

A. Its use is to afford space for dry steam to collect.

Q. What is a mud drum, and of what use is it?

A. The mud drum is cylindrical in shape, made of boiler iron flanged and riveted over a hole on under side of boiler, in which mud and sediment may collect, and is of great value on a return flue boiler.

Q. What are boilers furnished with so that they may be easily cleaned?

A. Man-holes and hand-holes.

Q. What are man-holes and hand-holes?

A. The man-hole is a hole cut in boiler large enough to admit a man and is covered by a portable plate which can be fastened absolutely tight. Hand-holes are small holes cut in boiler in convenient places into which a hose can be placed and the boiler washed out and the mud and scale removed. Hand-holes are covered with portable plates which can be fastened absolutely tight.

Q. How can a boiler be protected from the cold?

A. By a non-conducting jacket which keeps off the cold, retains the high temperature of the boiler and prevents the radiation of heat.

Q. What materials are used for jacketing a boiler?

A. Plaster, wood, hair, rags, felt, paper and asbestos.

Q. How are they applied?

A. Wood is put on in long strips close together like barrel staves, fastened with hoops and usually covered with sheet iron. The other materials are put close to the boiler and held in place by sheet iron or canvas. They are sometimes put on with an intervening air space between them and the boiler.

Q. What is the use of air space?

A. It protects the material from being burned or otherwise injured by the heat.

Q. Is there no radiation through these coverings?

A. Yes, but the loss is very slight, as the temperature of covering should never rise above what just seems warm to the hand.

Q. How should you feed water to a boiler?

A. Continuously during the whole time that steam is being used.

Q. Will a steam pump feed continuously?

A. Yes, by running the pump faster or slower according to the amount of water required.

Q. Why is a continuous feed preferable?

A. Because it maintains the water in the boiler at a uniform level and gives the most perfect action.

Q. Should precaution be taken in choice of water used in the boiler?

A. Yes. Always use water that is as clear and free from foreign matter as can be procured, rain water preferred.

Q. What is the result of using impure water?

A. It will form a scale upon the flues and plates on the inside of boiler.

Q. What harm does scale do?

A. In the first place scale is a non-conductor and prevents the heat of furnace from producing its best effects upon the water and in the second place it allows the plates and flues to become over heated and burn.

Q. How can you prevent the formation of scale?

A. There are numerous compounds upon the market some of which are known to be very reliable, but for ordinary purposes sal soda dissolved in the feed water answers very well.

Q. What precaution should be taken in the use of sal soda?

A. Great care should be taken that too much is not used at a time. If too much is used a great deal of trouble will be caused by the water in the boiler foaming.

Q. How often should a boiler be cleaned?

A. It depends entirely upon the condition of the feed water used and the amount of service exerted from it. It may vary from once or twice a week to once in two or three months, or even longer.

Q. Does a boiler only require the regular cleaning?

A. No, it should be blown off three or four times a day by the surface blow-off.

Q. Should the surface blow-off be left open any length of time?

A. No, only a few seconds at a time, say from fifteen seconds to a minute, even longer on larger boilers, but the engineer must use his own judgement in this matter.

Q. What does the surface blow-off do?

A. It blows out all the impurities that arise in the form of scum on the surface of the water, thus lessening the amount of scale formation.

Q. How should a boiler be cleaned?

A. By blowing the water out at a low pressure of steam and after cooling off wash out and scrape the inside, removing all scale and sediment.

Q. How do you blow off your boiler?

A. By means of a blow-off valve situated at the bottom part of the boiler.

Q. When should a boiler be blown off?

A. When the steam pressure entirely disappears and the water is at boiling point, if boiler is set in brick work.

Q. Why not blow off under a full head of steam?

A. Because when blown off under pressure there is heat enough remaining in the shell and flues to bake the scale upon the interior, thus rendering it exceedingly difficult to remove.

Q. In what condition is the scale after blowing off at low pressure.

A. Some may be baked hard and attached to the flues and shell, but the greater part will be soft and slushy so that it can be easily removed.

Q. How is this slush removed from the boiler?

A. If a fire box or return flue boiler, all the hand-hole plates should be removed and as much of the slush as possible raked out; then a hose is inserted and a stream of water forced in which will carry the remainder out. The hose should be placed in the top holes first.

Q. Is it a good idea after blowing off a boiler to fill it with water again without delay?

A. No. Because the boiler is hot, and if cold water is put in before it is thoroughly cooled off the boiler will be subjected to severe strains caused by the sudden contraction of the metal that is expanded by the heat, which will injure it to a greater or less degree.

Garr-Scott Traction Engine.

GARR-SCOTT TRACTION ENGINE.

This engine, as will be seen by examining the cut, is of the Side Crank, Side Gear style, the engine of which is mounted upon a long heater, to which the cylinder and the main pillow block bearing are attached, and is supplied with the bar or locomotive guides for cross-head.

It is fitted with the Link Reverse peculiar to their own style of manufacture, also Injector, Friction Clutch, Cross-head Pump, Governor, Syphon for filling Tank on front end, Automatic Sight-Feed Lubricator, and large Foot Board with Tool Boxes attached.

The boiler is of the locomotive or round bottom fire box type, with dome on front end, and is mounted upon the traction wheels with axle arms attached to the sides of boiler, which are supplied with springs. The front axle is attached to the boiler with a bolster arrangement, which is also supplied with a spring.

The traction wheels are made practically in one piece, having the spokes cast in both hub and rim, the cast iron rim being chilled faced, with the mud cleats cast on.

The smoke stack is supplied with a screen suitable for burning either wood or coal. It has a patent steering attachment, the hand wheel of which is on the same side of engine as the band wheel.

The engine and boiler are supplied with all the necessary fittings to make them convenient and safe with proper handling.

Q. When should a boiler be filled after being blown off and cleaned?

A. A boiler should not be filled under any circumstances until it is about the same temperature as the water used to fill it.

Q. How are the hand-hole plates put back in position?

A. The plate that covers the hole is put on the inside of the boiler and held in position against the plate by a bolt attached to it and passing out through a yoke which straddles the hole upon the outside and serves as a brace against which the bolt acts.

Q. How is a leak prevented?

A. By placing packing between the hand-hole plate and the boiler plate.

Q. What is the best kind of packing to use for this purpose?

A. Two or three ply sheet rubber is the best, cut in the form of a ring to fit the bearing surface of the plate.

Q. Can any other material be used?

A. Yes, hemp or cotton packing. When this is used it should be pulled out in fine shreds and thoroughly oiled before putting in position. Use as little as possible.

Q. Do the metals need any preparation?

A. Yes, all the old packing that may have burned on the metal should be thoroughly scraped off, also the scale should be removed from the vicinity so that the packing will have a smooth and even surface to bear against.

Q. How are man-hole plates put in position?

A. In the same manner as the hand-hole plates.

Q. What is required of an engineer or fireman in the care of a boiler?

A. He should watch carefully all the parts that are exposed to any steam and see that they do not become unduly weakened by corrosion or accident. All the working parts and fittings should be examined daily and be repaired or replaced as soon as they show signs of wear or weakness. The steam gauge and safety valve should receive constant care and both should be tested frequently, the one by the other, and the steam gauge by a standard in order that it may be known to be in perfect order. When scale forming water is used the feed pipe should be frequently uncoupled and examined and all sediment removed. The check valve should be examined frequently to see that it seats properly so that water cannot leak from boiler in this way and the utmost care should be taken in regard to the consumption of fuel.

Q. In case of accident how should an engineer conduct himself?

A. With the utmost coolness.

Q. If the water gauge glass breaks, what should be done?

A. The upper and lower gauge valves should be closed immediately.

Q. Can a new glass be put in at once?

A. No, because a new glass is cold, and if put in position and steam turned on, the sudden heat and expansion would be apt to crack it.

Q. When can a new glass be put in?

A. After the boiler has been cooled off.

Q. What is to be done in the meantime?

A. The boiler must be run by the use of the gauge cocks alone.

Q. What is to be done if the gauge cocks leak?

A. If the leak is in the seat, that part should be taken out and re-ground and refitted. This should be done at once.

Q. What harm is done by a leaky gauge cock?

A. It allows the water to run down over the face of the boiler, which tends to corrode it.

Q. When the leak is where the gauge cock is screwed into the boiler, what is to be done?

A. As soon as the boiler is cooled down examine and see if the gauge cock can be screwed up another turn. If so try that, then if the leak is not stopped the gauge cock must be taken out and a new one put in its place, or the thread of the old one so repaired that there will be no leak.

Q. Why not screw up the leaky gauge cock when the boiler is under pressure?

A. Because there is great danger of breaking the cock, thereby placing the engineer or fireman in great peril.

Q. What should be done in case a gauge cock is accidentally broken off?

A. Open the furnace door and if possible partially bank the fire, close the damper and allow the water to blow out at the hole until steam alone comes out. In the meantime get a piece of soft pine six or seven feet long and whittle down one end until it will about fit and jam it into the hole. Work it around until the jet of steam is stopped. Fasten the stick in temporarily and stop the engine if not already done. It will now depend on the condition of the break and the position of the surrounding parts as to the means to be employed. The stick should be cut off short and firmly driven into the hole and braced or tied securely. The engineer or fireman must use his own ingenuity for this work.

Q. Can a boiler be worked in this condition?

A. Yes, by the use of the gauge glass to determine the level of water.

Q. Should a boiler be run in this condition continually?

A. No. A new gauge cock should be supplied as soon as possible.

Q. When a gauge cock becomes stopped up what should be done?

A. After steam is down, the front or outer part may be taken off and a stiff wire run into it to open the clogged tube.

Q. Is it simply necessary to get the wire through?

A. No, the wire should be worked back and forth until all the deposit or scale is thoroughly cleaned out.

Q. In case the steam gauge gets out of order what should be done?

A. There should always be an extra gauge on hand that may be put to use. If there is no extra steam gauge, the engine should be shut down until the gauge can be repaired.

Q. Why not continue running by using the safety valve?

A. Because it is very dangerous and should never be attempted.

Q. How much variation from the actual pressure can be allowed on steam gauge before it is repaired?

A. None. As soon as suspected of being even slightly out of order it should be repaired.

Q. In case the pump does not work what should be done?

A. Supply the boiler by the injector.

Q. What is to be done where there is no injector?

A. First, care should be taken that the water in the boiler does not fall below the second gauge cock or out of sight in the gauge glass, then stop the engine and bank the fire. When this is done, examine the packing around the plunger to see that it does not leak air, then examine the valves of the pump to ascertain whether they are worn and leak. If this be the case they must be reseated at once. If the valves are all right, work the pump and open the side valve in the delivery pipe to see if the pump draws water. If no water appears, the trouble is probably in the suction pipe.

Q. How can this be remedied?

A. First examine the strainer at end of suction pipe or hose to see if it is stopped up; if it is, clean it out and try the pump. If it works, the difficulty is remedied. If the strainer is clean, examine the pipe or hose from end to end to see that it is perfectly air tight; if not, it should be made so.

Q. If the delivery pipe is choked, how can it be cleaned?

A. Close the globe valve next to boiler, and then examine the check valve to see if it is all right. If it is choked or filled with sediment, take out the valve, clean the shell and re-seat the valve; if the check is all right, disconnect the pipe and clean out if necessary.

Q. What if this pipe and check valve are all right?

A. Let the boiler cool off, then blow off the water, disconnect the pipe between check and boiler, where the difficulty will probably be found, and clean thoroughly.

Q. How can check valve and delivery pipe be choked with water that has already passed through the injector or valves of the pump?

A. The water may contain quantities of lime which are deposited from the heated water upon the interior of the pipe, which will thus be gradually decreased in size until the hole is too small to answer the purpose.

Q. When the communication between the water gauge and boiler is interrupted, what should be done?

A. The glass should be blown out frequently by opening the drip cock at the bottom, then shut the upper valve, allowing the water to blow through the lower valve until the water runs free and clear. Then shut the lower valve and open the upper one and blow through in like manner.

Q. In case of low water what should be done?

A. Cover the fire quickly with fresh coal or damp ashes, close the lower draft door, and allow the furnace to cool. Never dash water into the furnace to check the fire, it is dangerous.

Q. Why not draw or dump the fire?

A. Because it would result momentarily in stirring up an intense heat, cooling can be effected more rapidly by covering the fire and checking the draft.

Q. Should the pop or safety valve be opened?

A. No. Never let more steam out of the boiler in this condition than can be avoided.

Q. Should the engine be stopped or the throttle valve be closed?

A. No. A sudden stoppage of the outflow of steam will cause the water level to fall. The first thing to be looked after is to subdue the heat which is the source from which trouble may arise.

Q. Should the feed water supply be turned on?

A. No. Leave it alone. Should the pump or injector be running, the water level will be recovered gradually as the boiler cools down. If the feed is not on, the sudden admittance of water on the overheated surfaces will cause a disaster. The feed should not be turned on until sufficient time has been allowed to avert such danger.

Q. Are there any appliances by which to guard against accident from low water?

A. Yes. Alarms to call attention by blowing a whistle or ringing a bell when the water is below a certain level. Also fusible or safety plug placed in the heating surface of boiler most liable to be overheated from lack of water.

Q. Of what use is the safety valve?

A. To prevent the accumulation of pressure above a given point.

Q. Should water be left in the boiler when not in use?

A. No. It is better to draw out all the water and properly clean the boiler before leaving.

Q. What should be done in case a grate bar breaks and drops out of place?

A. If no other bar is at hand, it might be repaired with a heavy stick of wood.

Q. How can this be done?

A. By cutting the stick in such a shape as to fit the space made by the broken bar, then cover with ashes before the fire spreads over it.

Q. Will the stick burn out?

A. Yes, but it will last for several hours.

NICHOLS & SHEPARD TRACTION ENGINE.

This engine is also of the Side Crank, Side Gear pattern, the engine is mounted upon the side of the boiler, upon a long heater, which is securely bolted to the boiler by three brackets. It is of the Locomotive Guide pattern, and has a cross-head pump. The cylinder rests its full length upon the heater and is lagged. It has the link reverse gear and plain slide valve, Friction Clutch, Injector, Automatic Sight Feed Lubricator, Governor, Extension Front and Straight Stack. The hand steering wheel is on the opposite side from the band wheel.

The boiler is of the round bottom fire box style with double riveted seams, and has a dome in the center, and is mounted upon the wheels in the rear with a wrought iron axle which passes around underneath the boiler and is held in place by brackets attached to the side of the boiler.

These brackets contain springs.

The traction wheels are of the cast iron rim style, with wrought iron spokes cast in both rim and hub and mud cleats are cast on rim. The foot board is furnished with a water tank and tool box and all necessary fittings and attachments are supplied to make a complete traction engine.

Nichols & Shepard Traction Engine.

Q. What harm would result from firing for a short time without the bar?

A. None to speak of to furnace or grate bars, but the quantity of air admitted to the fire box would make it exceedingly hard to keep up steam and the hole thus made would cause a great loss of fuel.

Q. What should be done if a bar in a rocker grate should fall out?

A. Take a piece of flat wrought iron and cut it to fit the bearings, this will do for some time and will not interfere with the rocking of the bars. Or, take a heavy piece of plank, covering the opening completely, and cover the plank carefully with ashes, surrounding it on all sides to protect it as much as possible from the fire.

Q. Will not this latter prevent the rocking of the grate?

A. Yes, and it can only be cleaned by raking out from underneath.

Q. How should such difficulties be avoided?

A. A good engineer will always have on hand at least two or three extra grate bars.

Q. Should a boiler be forced beyond its normal capacity?

A. Never force a boiler beyond its normal capacity, as such excessive firing distorts the fire sheets and results in leaks and fractures.

Q. Should intense fires be started in or under boilers?

A. Never build an intense fire in or under a boiler until the shell is well heated. Hot fires in or under cold boilers hurry their destruction.

CAUTION.

Never blow out the boiler under high steam pressure or fill it again with cold water when the boiler is hot, as either one of these is likely to fracture the transverse riveting and is dangerous.

Do not feed the water to the boiler irregularly. The slower the water goes through the heater the more heat it takes up. To fill the boiler to three gauges and then shut off the feed until the water level is again down, the exhaust steam, after it has heated the water standing in heater, passes off without leaving any of its heat, and then turning on the feed water again much faster than needed, the water has not time to take up so much heat as if the feed were slow and regular. Much bad effect on the boiler is due to the difference in temperature at the time when the feed is off and on.

Never calk a boiler under steam pressure unless you are tired of life.