How to run engines and boilers. Practical instruction for young engineers and steam users

Front matter

LIBRARY^F^ONGRESs;

Shelf. Xi..?/ '

UNITED STATES OF AMERICA.

CHAPTER I. Cleaning the Boiler -- page l

Removing Scale- 5

CHAPTER n.

Using Scale Preventers — 7

Oil in Boilers - -- 9

Braces and Stays -• 9

CHAPTER HI.

Mud Drums and Feed Pipe - - 11

Boiler Fittings - ----: 13

CHAPTER IV.

Grate Bars and Tubes ' -- 15

Bridge Walls--- - ---- 17

The Slide Valve Throttling Engine 18

CHAPTER V.

The Piston 22

The Slide Valve - - - 24

CHAPTER VI.

Testing the Valve with Relation to the Ports - - 27

Defects of the Slide Valve - -- ---- 30

CHAPTER VII.

LapandLead- - - 33

The Pressure on a Slide Valve 34

Stem Connections to tlie Valve--- 36

CHAPTER VIII.

Valves off their Seats 40

Valve Stem Guides - -- 41

Governors - -- 42

Running with the Sun 44

CHAPTER IX.

Eccentrics anrl Connections — --- - 46

The Crank Pin 48

Brass Boxes - - - - - - 51

Bearing on Pins - --- 53

Fitting Brasses to Bearings 55

CHAPTER X.

Adjustment of Bearings - - 57

Tlie Valve and Gearing - - 59

CHAPTER XI.

Setting Eccentrics -- - 65

Tlie Actual Operation 67

CHAPTER XII.

Return Crank Motion 74

Pounding - --- 75

Tlie Connections — 77

Lining Up Engines - - 82

CHAPTER XIII.

Making Joints — - -- 88

CHAPTER XIV.

Condensing Engines 93

CHAPTER XV.

Torricelli's Vacuum - - - 100

Proof of Atmospheric Pressure - - 101

No Power in a Vacuum 101

CHAPTER XVI.

Supporting a Water Column by the Atmosphere 107

CHAPTER XVII.

Starting a New Plant 114

CHAPTER XVIII.

The Highest Qualities Demanded- — 122

The Man Himself the Factor - 123

Lastly - - 124

HOW TO RUN ENGINES AND BOILERS.

CHAPTER I.

The first thin^ to be done upon taking charge of an engine and boiler, new or old, is to examine the boiler thoroughly. No matter whether it has just come from the shop, or has been run for years, take off the man-hole plate and go inside yourself with a hand-lamp ; after you are in look at all the water spaces, and see if they are clean, that is, without rubbish or dirt of any kind. Even new boilers are not free from this. There are various irresponsible persons about boiler shops who are not as careful as they should be, and it will be the exception rather than otherwise if you do not find a lot ot things which are better out of the boiler than, in it. In large boilers rivet kegs are often taken in to sit upon, and are not always taken out again ; the staves are thrown down in the water space, from whence they will float out and get in the steam pipes by some mysterious happening. The water line is not so high as the steam pipe, by any means, but the staves get there somehow ; so do bunches of waste, etc. Everything of any kind should be cleaned out of the boiler before vrater is run into it. To do this it will be necessary to take off the lower hand-hole plates, and with a small hooked rod dislodge everything that is loose in the boiler.

Spare no pains in this work, for it will be labor and money saved in future. When the boiler is thoroughly clean you can put the plates in again, but before doing this rub the gaskets thoroughly w^th plumbago, and they will not adhere to the plate where exposed to heat. This is a saving of time and gaskets in breaking joints in future. The old way of making joints upon hand-hole plates, with hemp gaskets slushed with white lead, has gone out of use, having been superseded by rubber gaskets made for the purpose. If you are remote from a city, however, and cannot get a rubber gasket, you can make a hemp gasket which will answer all purposes. Jute is the best material for this job if it can be had, but you are quite as likely to be out of jute as out of rubber gaskets, and if you have neither you can get a clothesline most anywhere. Unlay this and take the twist out of it; beat it with a flat stick so as to reduce it to its original fiber ; then braid it up again of the proper size for the job in hand. Find the right length for the gasket, and join the ends so as to form a ring of the proper size that will fit the plate accurately : it should go on so tight that you have to force it over the flange of the plate. Cover this gasket thoroughly with white lead, and then put it in its place. It will be absolutely tight if the v/orkhas been properly done. Cleaning the Boiler.

We have been assuming that the boiler you have taken charge of is a new one, without scale, but it it is an old one there is likely to be a quantity of scale and dirt, which must be taken out at once. The way to do this is to us the best tools you can get hold of, or contrive for the purpose. The place to look for dirt and deposits from the feed water is in the bottom of the boiler furthest from the entrance of the feed water, and in the parts that are the coolest, if there are any, when the steam is on. In a return tubular boiler this is generally in the smoke-box end, which is not so hot as the fire-box end; the quantity of rubbish which accumulates in a neglected boiler is astonishing, and you must not be surprised if you have to remove wheelbarrow loads. This dirt comes from the solid matter in the water, both that which is carried in mechanically from turbid supplies, and that which is held in suspension until set free by heat. Every gallon has a certain amount, and as many gallons are evaporated daily, unless removed weekly it soon makes a wheelbarrow load. This dirt, by backing- up against the flue sheet, deprives the ends of the tubes of water, which not only steals part of the heating surface, but destroys the ends of the tubes and flue-sheet by corrosion and over heating, so that it is only a question of time when the boiler will be practically useless. If the lo\\'er course of the tube-ends in the smokebox leak, be sure that they have been abused in the manner stated. You will probably find that they will leak after dirt has been cleaned out. In that case the tubes must be re-expanded, and to do this a boiler maker must be called in. Do not, upon any consideration, try to tinker them up with a hammer yourself. You will only make a bad matter worse, and set other tubes to leaking which were tight. Having taken out what may be called the "loose dirt," though some ol it is very far from being loose, you will find another job in front of you, and that is to get out the dirt which is fast. In other words, the scale. This is actual stone, artificially formed within the boiler from the working of it. It differs in character with the kind of water used. If it is hard water, so-called, it will be limestone scale ; if soft water, it will be sulphate of magnesia and soda scale ; either one of them is bad enough, so far as the boiler is s

concerned, and must be removed absolutely if there is to be any economy.

Removing Scale.

There is a way to do this which we have practiced with success, and that is to run the boiler full of water up to the third gauge and then put in a quantity of a scale preventive. Of these there are numbers in market, but we do not name any one as the best. Doubtless none of them are wholly useless, though some of them are inert or do not act. You will have to find out by experience which one serves your purpose. Sometimes caustic potash answers a very good purpose. This when the scale is chiefly mud with sulphate of soda and magnesia combined. Caustic potash is the concentrated lye sold in grocery stores, but if wanted in large quantities should be purchased of wholesale druggists. To use it, dissolve it in a barrel of water, say 40 pounds to the barrel, and pour it into the boiler. This is about one-sixth of a pound of potash to the pound of w^ater, and is strong enough for the purpose. After the purger is in the boiler build a light fire and heat the water to boiling point, and then haul the fire and let the contents stand. It is better to do this on Saturday night, if possible, leaving the water in the boiler until Monday morning ; you should then get up steam to, say, five or ten pounds pressure on the same water, haul the fire all out, and blow the boiler down. You will, in the majority of cases, find the boiler thoroughly clean, except for chunks of scale which cannot go through the blow-cock, and which must be taken out through the hand-holes.

Caution.

In handling caustic potash the utmost care must be used. It is truly caustic, or burning, and if a portion gets in the eyes it will cause serious trouble. The same is true of sores on the hands. Handle it with gloves ; treat it very respectfully.

CHAPTER II. Using Scale Preventers

If caustic potash cannot be had, a substitute may be found, in rural districts, in slippery elm bark. This is not at all caustic, but quite the reverse, being demulcent in character. How it acts we do not know ; but that it has a certain efficiency we do know, because we have cleaned boilers thoroughly with it. It makes little difference how much is used, put it in the boiler and let it stay there for a week, and there will be a benefit from its use.

These purgers just named are only of service where the scale is soft ; for hard scale a different one must be used, and to attack lime scale it should be of an acid character, for lime is alkaline, and its antidote is an acid. But just here trouble is likely to ensue in the hands of an inexperienced person. A good many will exclaim loudly against using an acid purger in a boiler, arguing that it will destroy the boiler as well, and that very soon. Some have shown us pieces of iron, that they immersed in certain boiler purgers, that were badly corroded. This is very likely, but it so happens that no boiler purger is used in that way. The purger is largely diluted with water, and acts very slowly upon the iron. It attacks the scale first, because it has the greatest affinity, or liking-, for it ; after that it goes for the boiler plates ; but there are no after effects of this character from a boiler purger, because it is no longer in the boiler when the scale is removed, and if a boiler is thoroughly washed out there is no danger to it from the use of a strong purge. There is very great danger from the presence of heavy lime stone scale, and since nothing but a purger with an acid reaction will remove it, we do not fear to use it ourselves. Some engineers have shown us boilers from which the scale was removed which had the plates badly corroded. This action was attributed to the use of the purge, when it was, in fact, caused by the scale itself. The corrosion was going on all the time underneath the scale, and when it was removed the injury it caused was manifest. Ot two evils we are taught to choose the least, and in this case the use of a strong boiler purger is less than the injury and loss of fuel caused by scale. Get that out first, thoroughly clean the boiler after of all traces of the purge, and there will be no trouble arising from its use. It is understood, of course, that after the use of any boiler purge that the hand-hole plates must be taken off and the boiler cleaned out by hand, washed with a hose, and then filled up and blown out again

9 before steam is raised. There is no middle g^round or half-way measures possible in dealing with a dirty steam boiler. Get down to the naked iron and keep it so, inside and out, and the boiler twenty years old will steam as freely as one just out of the shop. Oil in Boilers.

Do not upon any account put crude oil or any other kind of g-rease in a steam boiler. It generally gets in fast enough through the feed water where open heaters are used, without putting it in. The effect of putting oil in is, in a great many cases, to cause the crown sheet to come down, or the lower sheets to bag. When first put in the oil floats, but it gradually picks up scum from the surface, in which scum there is always more or less actual mud thrown up from the bottom by the boiling water; the oil then becomes like tar, and being heavy settles on the plates and sticks fast. Since the water cannot get underneath it the plates are overheated' and come down, notwithstanding the fact that there is plenty of water in the boiler. Keep every kind of grease out of a steam boiler, if you have to filter the feed water to do it. Braces and Stays.

We have now a clean boiler to deal with ; let us see in what condition it is as resfards strength. The braces are the first to be considered. Perhaps some of them are carried away entirely; such a state of things is by no means unknown. They must be replaced at once by boiler makers, who should also go over every other part of the boiler and test it for condition; but if there are no boiler makers handy the engineer must do it himself. The boiler most generally used is the return tubular, which is a plain cylinder with an external fire-box, from which the heat traverses the bottom and enters the tubes at the back, passing through them to the breeching and smoke-stack in front. The weak point in the return tubular boiler is directly over the bridgewall, where the heat deflected from the wall strikes upon the shell. This spot needs to be carefully examined, for unless the boiler hj^s been well taken care of it wll be found weak and unsafe. If any doubt exists, a half inch hole should be drilled in the bottom to ascertain the exact thickness of the plate, when, if thinner than the shell elsewhere, it should be removed, and a new plate put in. The sides of the boiler should also be examined near the wall, or where the boiler meets the brick- work, for here there is often trouble from corrosion ; also at the junction of the blow-pipe in the bottom or at the end of the boiler.

CHAPTER III. Mud Drums and Feed-Pife

If there is a mud-drum attached to the boiler examine it very thoroughly, for explosions of mud-drums are very common. If the mud-drum is buried, as it often is, it is probably corroded greatly. The proper place for a mud-drum is outside of the boiler, in plain sight, where it can be got at and cleaned out weekly. The object of it is to catch all the free mud, so to call it, which is thrown down at night when the boiler is not running. With some water used for steam making, as on Western rivers, the quantity of mud so deposited is very large, and if not removed it will be driven back into the boiler. This is particularly true where the feed pipe enters through one end of the mud-drum. It does not require much thought to see that this wholly defeats the object of the mud-drum, for the sediment which collects over night is forced through the boiler again at the first stroke of the pump in the morning.

As to the best place for the feedpipe to enter the boiler there is a difference of opinion among engineers, but there is no doubt but that the worst place is through the mud-drum, for the reason given. Some think that the feed should enter the coolest part; some put it in the steam space, and some enter it at the front end alongside the fire. An objection to this is the bad effect of water cooler than the water in the boiler upon hot plates; an advantage is the propulsion of any sediment that may lie upon the bottom of the boiler to the back end of it, where there is no trouble in removing it; another benefit is that the mechanical action of the entering jet assists the circulation by forcibly driving the heated water from the front to the back, and replacing it with cooler water, but to effect these objects the feed pipe must project within the boiler for a few inches so as to give what we shall call a straight shot from it.

Boiler Fittings.

In these are included every sort of attachment to a boiler, the water gauge, gauge cocks, safety valve, checks of all kinds, and the blowoff valve or cock for blowing the water out of the boiler. This last is a much more important detail than it is generally supposed to be, and many accidents nave happened from careless^ ness with it. These accidents occurred from "sticking" any sort of a bent pipe (we have actually seen an old leader pipe from a house used) over the end of the nipple or elbow on the blow-pipe. The blow-pipe connection

13 should be made as firmly and as securely as any other attachment to a boiler. If one reflects for a moment, it is easy to see that there is a tremendous strain on a pipe which is discharging a two inch stream of water under 60 or 70 pounds pressure. A boiler never should be blown off at this pressure, but it sometimes has to be, and preparation should be made for it. No elbow^s should be used where it is possible to avoid them ; the pipe should run as straight as it can from the boiler to the outer air, and if a cock is used care should be taken that it is always in perfect order. It should not leak a drop ; the bolt at bottom which keeps the plug in the cock should be accurately fitted, of full length, entering the plug not less than i^ inches, and have a good head on it. It must never be meddled with or touched, except to open or close it, when under pressure. Don't hit it with a hammer, either on the under side to start the plug up if it sticks, or on the top for any purpose. Remember that it is under pressure, and if it gives way it is almost certain death to any one near it. Defer all tinkering and investigation until the boiler is cold; or, in other words, make everything secure before steam is on; then there will be no trouble. Forethought, care, and caution, are absolutely indispensable qualifications in an engineer, and it is useless to expect success or ordinary economy without them. No man can be an engineer worthy of the name who is careless or has not his v/its about him at all times. ^Ir. I-Didn't-Think has no business with a steam boiler.

What has been said of the blow-cock is true of all the other fittino^s. Every one of them must be in perfect order to be safe and efficient; an engineer must bear in mind that he is dealing with a tremendous agent, which is safe only when in its place and under control, and every gauge or fitting of every kind must be securely in place and tight of itself, that is, tight without makeshifts of any kind.

The safety valve in particular must be tight, for a great deal of coal can be lost by a leaky valve. It should be free and clear in the hoist, or where the lever is to be raised — if it is of the lever type — and entirely free from rust in all parts. A safety valve is for use, not for emergency, and if it is not in order it will not act when the emergency comes, if it ever does.

It is not every engineer that can do the work which we have mentioned wuth his own hands, for not all persons in charge of engines are machinists; these instructions convey a knowledge of what is needed, and the work can be supplied by those competent to perform it.

CHAPTER IV. Grate Bars and Tubes

One of the most important parts of a boiler is the g-rate. Curiously enough but few give this matter sufficient thought, but it is plain upon reflection that the air which is needed to support combustion must be supplied through it. If the bars are warped and broken, too much air goes through them, with the effect of wasting fuel or checking the free s'.eaming of the boiler. Moreover, a broken grate bar prevents proper firing, or attention to the fire ; all the bars should be in good order, with no open spaces at the ends (front or back) or sides. As this bears directly upon the subject of combustion, it will be more explicitly alluded to further along in this w^ork.

The tubes or flues particularly demand attention, and must be absolutely clean inside and out. In a former article we have given directions how to clean them outside — that is, on the water side, but they must be clean on the fire side too. With anthracite coal this is not a matter of difficulty, but with soft coal it is ; not so much through the soot which accumulates in them as with the " gurry," for want of a better name, which is burned on. This last is the tarry distillates of the coal, or heavier i6

products of combustion, which are condensed on the inside of the tubes when the boiler is comparatively cold, or in getting up steam every morning, and is by no means easy to remove. It not only checks steam making by obstructing the heat from passing through the tubes, but it hinders the draught by the adherence of soot and roughening the surface of the tubes. It would seem that the fire should burn this deposit off, but it requires a much higher temperature to do this than that m the tubes, and the only way to remove it when it has accumulated in quantity is to thoroughly slush the tubes with crude petroleum oil, applied with a swab and allowed to remain for a day or so, when it should be sw^abbed out again. This is a job which but few persons care to undertake, particularly if the boiler is large, but in some cases it becomes neccessary. Crude petroleum is a solvent for tar, and will clean the tubes thoroughly.

Of course it has to be undertaken in holiday time, when the boiler is idle for a day or two, for to be of any service the oil must remain in the tubes at least 24 hours. It is of no use to try to rasp this " gurry" out with steel brushes or scrapers. It is as tough as India-rubber and a scraper slides over it.

17 Bridge Walls.

The bridge wall in a boiler is intended to delay the products of combustion in the fire-box as long as possible, and to confine the heat from the fire within the area of the grate. To do this it is manifest that the throat, or opening over the bridge wall, between the top of it and the boiler, should be as small as it can be, and leave room enough for a good "draught," so-called. There is, however, a danger in this, and this danger is that if the throat is too narrow, the heat, and sometimes the flame, is sharply deflected and concentrated directly upon one spot over the wall. The result of this is that the sheet for a foot or so is fire-eaten, or thinned and weakened ; it is burned, as boiler makers would say, notwithstanding there may have been plenty of water in the boiler. The opening over the bridge wall should never exceed ten inches, nor be less than eight inches, and it should follow the curve of the boiler. There are a great many patents on bridge walls which are intended to improve the combustion by admitting air over them, or through them, but never having had any experience with them we cannot say anything about them.

Assuming that the boiler has been put in good condition, we will look at the engine.

i8

The hints given in the previous chapters should enable any intelligent man who is fit to be about a steam plant, to have a boiler v\^hich v^nll steam freely and as economically as its construction viull allow. A treatise could be written upon boilers alone, and many such works are in existence. The contents, however, relate more particularly to the construction, a matter which does not enter into an engineer's duties.

The Slide- Valve Throttling Engine. The commonest form of steam engine in use to-day is the slide-valve throttling engine, which is regulated by governors of various kinds. It is the simplest of machines, easily managed by any one after a little instruction, and frequently is found in charge of men and boys who have had no experience whatever, they merely knowing that a certain valve has to be opened, and that the engine must be at half-stroke to start. Such persons are not engineers in any sense of the word, for they do not intend to follow^ the business any longer than they can help. Our instructions are not directed to them, but to intelligent young men who have started with the intention of learning all that they can. The first thing to do then in taking charge of an engine is to see in what condition it has been handed over, in order that

19 you may not be blamed for the sins of those who preceded you. The cylinder is the seat of power, and we want to examine it as soon as we can get a chance. If we have been under steam the day before, we leave the engine on the back center at night (Saturday night foi instance), and take off the cylinder head. The piston is then at the end of its stroke, and we have an opportunity to see what the clearance is between the piston and the cylinder head. The latter detail will leave its mark on the cylinder after it is taken out, so it will be easy to measure directly from the piston to the said mark. Some clearance is necssary for safe working, but it should be just as little as possible; clearance is waste room that has to be filled with live steam at every stroke before any work is done on the piston.

As a rule excessive clearance is given in small engines, for no reason whatever, except that some builders appear to think that there is less danger of breaking down. Suppose that the cylinder is 12 inches diameter: then the piston should run within one-quarter of an inch of the head. If the piston is of that class where the follower bolts stick out the depths of their heads, it cannot run so close as this, and probably there is an inch or more clearance in such a cylinder, but it is easy to reduce the clearance in such cases to the lowest point and this is easily done by taking the follower to a machine shop and having the bolt holes counterbored, so as to let the heads in as far as possible; having done this, fill up on the head itself by bolting on a cast-iron plate of the required thickness, cutting out where it covers the steam port. The reduction of clearance often makes a boiler much larger; or, in plainer terms, since less waste occurs it is easier to keep steam on a boiler than when the clearance is excessive. Having found what the clearance is on the back end then, we disconnect the piston from the cross-head, and (running the crank on the forward center), we find what it is on the front end. This we do by shoving the piston clear up against the forward head. Having done this we measure from the follower back to the end of the stroke, as shown by the wear on the guides, and the wear on the cylinder itself. If this measurement is half an inch longer than the working stroke of the piston, there is half an inch clearance on the front end, and as there are no follower bolts on that end it is all waste, except so much as is actually needed for the safe working of the engine. We should, if the engine was ours, reduce this clearance also, to the same degree that we did the back end, but as it entails more or less work for the shop, it will be as well to leave the clearance half an inch on the front end; if the clearance is one inch, however, no consideration of trouble or expense should be spared to reduce it in the sanae way that we fixed the back head, byadding to the head itself. The clearance in any eng'ine must be reduced to its lowest terms, for by doing this, if the engine is yours, you put money in your pocket; if it belongs to some one else and you are in charge of it, you get the credit of making a saving, and this will be a feather in ycur cap worth working for.