The Project Gutenberg eBook, Maxims and Instructions for the Boiler Room, by N. (Nehemiah) Hawkins

MAXIMS
AND
INSTRUCTIONS
FOR
THE BOILER ROOM.

This Work is Fraternally inscribed to W. R. Hawkins, R. F. Hawkins and F. P. Hawkins.

RICHARD TREVITHICK.

Maxims and Instructions
FOR
The Boiler Room.

USEFUL TO
Engineers, Firemen & Mechanics,
RELATING TO STEAM GENERATORS, PUMPS, APPLIANCES, STEAM HEATING, PRACTICAL PLUMBING, ETC.

By N. HAWKINS, M. E.,
Honorary Member National Association of Stationary Engineers, Editorial Writer, Author of Hand Book of Calculations for Engineers and Firemen, Etc., Etc.

Comprising Instructions and Suggestions on the Construction, Setting, Control and Management of Various Forms of Steam Boilers; on the Theory and Practical Operation of the Steam Pump; Steam Heating; Practical Plumbing; also Rules for the Safety Valve, Strength of Boilers, Capacity of Pumps, Etc.

THEO. AUDEL & CO., Publishers,
63 FIFTH AVE., Cor. 13th St.,
New York.

Copyrighted
1897—1898—1903
by
Theo, Audel & Co.

PREFACE.

The chief apology for the preparation and issue of these Maxims and Instructions, for the use of Steam users, Engineers and Firemen, is the more than kind reception of Calculations.

But there are other reasons. There is the wholesome desire to benefit the class, with whom, in one way and another, the author has been associated nearly two score years.

The plan followed in this work will be the same as that so generally approved in Calculations; the completed volume will be a work of reference and instruction upon those works set forth in the [title page]. As a work of reference the work will be especially helpful through combined [Index] and Definition [Tables] to be inserted at the close of the book. By the use of these the meaning of every machine, material and performance of the boiler room can be easily found and the “points” of instruction made use of.

This work being issued in parts, now in manuscript, and capable of change or enlargement, the editor will be thankful for healthful suggestions from his professional brethren, before it is put into permanent book form.

CONTENTS.

OLIVER EVANS.GEORGE STEPHENSON.ROBERT FULTON.

INTRODUCTION.

Each successive generation of engineers has added certain unwritten experiences to the general stock of knowledge relating to steam production, which have been communicated to their successors, and by them added to, in their turn; it is within the province of this book to put in form for reference, these unwritten laws of conduct, which have passed into Maxims among engineers and firemen—a maxim being an undisputed truth, expressed in the shortest terms.

Soliloquy of an Engineer. “Standing in the boiler room and looking around me, there are many things I ought to know a good deal about. Coal! What is its quality? How much is used in ten hours or twenty-four hours? Is the grate under the boiler the best for an economical consumption of fuel? Can I, by a change in method of firing, save any coal? The safety-valve. Do I know at what pressure it will blow off? Can I calculate the safety-valve so as to be certain the weight is placed right? Do I know how to calculate the area of the grate, the heating surface of the tubes and shell? Do I know the construction of the steam-gauge and vacuum-gauge? Am I certain the steam-gauge is indicating correctly, neither over nor under the pressure of the steam? What do I know about the setting of boilers? About the size and quality of fire bricks? About the combination of carbon and hydrogen of the fuel with the oxygen of the atmosphere? About oxygen, hydrogen and nitrogen? About the laws of combustion? About radiation and heat surfaces?

“Do I know what are good non-conductors for covering of pipes, and why they are good? Do I know how many gallons of water are in the boiler?

“What do I know about water and steam? How many gallons of water are evaporated in twenty-four hours? What do I know about iron and steel, boiler evaporation, horse power of engines, boiler appendages and fittings.

“Can I calculate the area and capacity of the engine cylinder? Can I take an indicator diagram and read it? Can I set the eccentric? Can I set valves? Do I understand the construction of the thermometer, and know something about the pressure of the atmosphere, temperature and the best means for ventilation? Can I use a pyrometer and a salinometer?

“Without going outside of my boiler and engine room I find these things are all about me—air, water, steam, heat, gases, motion, speed, strokes and revolutions, areas and capacities—how much do I know about these?

“How much can be learned from one lump of coal? What was it, where did it come from? When it is burned, what gases will it give off?

“And so with water. What is the composition of water? What are the effects of heat upon it? How does it circulate? What is the temperature of boiling water? What are the temperatures under different pressures? What is latent heat? What is expansive force?”

These are the questioning thoughts which fill, while on duty, more or less vividly, the minds of both engineers and firemen, and it is the purpose of this volume to answer the enquiries, as far as may be without attempting too much; for the perfect knowledge of the operations carried on within the boiler-room involves an acquaintance with many branches of science. In matters relating to steam engineering, it must be remembered that “art is long and time is short.”

The utility of such a book as this is intended to be, no one will question, and he who would not be a “hewer of wood and a drawer of water” to the more intelligent and well-informed mechanic, must possess to a considerable extent the principles and rules embraced in this book; and more especially, if he would be master of his profession and reputed as one whose skill and decisions can be implicitly relied upon.

The author in the preparation of the work has had two objects constantly in view; first to cause the student to become familiarly acquainted with the leading principles of his profession as they are mentioned, and secondly, to furnish him with as much advice and information as possible within the reasonable limits of the work.

While it is a fact that some of the matter contained in this work is very simple, and all of it intended to be very plain, it yet remains true that the most expert living engineer was at one time ignorant of the least of the facts and principles here given, and at no time in his active career can he ever get beyond the necessity of knowing the primary steps by which he first achieved his success.

The following taken from the editorial columns of the leading mechanical journal of the country contains the same suggestive ideas already indicated in the “soliloquy of an engineer:”

“There is amongst engineers in this country a quiet educational movement going on in matters relating to facts and principles underlying their work that is likely to have an important influence on industrial affairs. This educational movement is noticeable in all classes of workmen, but amongst none more than among the men in charge of the power plants of the country. It is fortunate that this is so, for progress once begun in such matters is never likely to stop.

“Engineers comprise various grades from the chief engineer of some large establishment, who is usually an accomplished mechanic, carrying along grave responsibilities, to the mere stopper and starter, who is engineer by courtesy only, and whose place is likely to be soon filled by quite another man, so far as qualifications are concerned. Men ignorant of everything except the mere mechanical details of their work will soon have no place.

“Scarcely a week passes that several questions are not asked by engineers, either of which could be made the subject of a lengthy article. This is of interest in that it shows that engineers, are not at the present time behind in the way of seeking information. Out of about a thousand questions that went into print, considerable more than half were asked by stationary engineers. These questions embrace many things in the way of steam engineering, steam engine management, construction, etc.”

The old meaning of the word lever was “a lifter” and this book is intended to be to its attentive student, a real lever to advance him in his life work; it is also to be used like a ladder, which is to be ascended step by step, the lower rounds of which, are as important as the highest.

It is moreover, the earnest wish of the editor that when some, perchance may have “climbed up” by the means of this, his work, they may in their turn serve as lifters to advance others, and by that means the benefits of the work widely extended.

MATERIALS.

The things with which the engineer has to deal in that place where steam is to be produced as an industrial agent, are

1. The Steam Generator.

2. Air.

3. Fuel.

4. Water.

5. Steam Appliances.

Starting with these points which form a part of every steam plant, however limited, however vast, the subject can easily be enlarged until it embraces a thousand varied divisions extending through all time and into every portion of the civilized world.

It is within the scope of this work to so present the subjects specified, that the student may classify and arrange the matter into truly scientific order.

MATERIALS.

In entering the steam department, where he is to be employed, the eye of the beginner is greeted with the sight of coal, water, oil, etc., and he is told of invisible materials, such as air, steam and gases; it is the proper manipulation of these seen and unseen material products as well as the machines, that is to become his life task. In aiding to the proper accomplishment of the yet untried problems nothing can be more useful than to know something of the nature and history of the different forms of matter entering into the business of steam production. Let us begin with

Coal.

The source of all the power in the steam engine is stored up in coal in the form of heat.

And this heat becomes effective by burning it, that is, by its combustion.

Coal consists of carbon, hydrogen, nitrogen, sulphur, oxygen and ash. These elements exist in all coals but in varying quantities.

These are the common proportions of the best sorts:

In burning coal or other fuel atmospheric air must be introduced before it will burn; the air furnishes the oxygen, without which combustion cannot take place.

It is found that in burning one lb. of coal one hundred and fifty cubic feet of air must be used and in every day practice it is necessary to supply twice as much; this is supplied to the coal partly through the grate bars, partly through the perforated doors, and the different devices for applying it already heated to the furnace.

WOOD.

Wood as a combustible, is divisible into two classes: 1st, the hard, compact and comparatively heavy, such as oak, ash, beech, elm. 2d, the light colored soft, and comparatively light woods as pine, birch, poplar.

Wood when cut down contains nearly half moisture and when kept in a dry place, for several years even, retains from 15 to 20 per cent. of it.

The steam producing power of wood by tests has been found to be but little over half that of coal and the more water in it the less its heating power. In order to obtain the most heating power from wood it is the practice in some works in Europe where fuel is costly, to dry the wood fuel thoroughly, even using stoves for the purpose, before using it. This “hint” may serve a good purpose on occasion.

The composition of wood reduced to its elementary condition will be found in the table with coal.

PEAT.

Peat is the organic matter or vegetable soil of bogs, swamps and marshes—decayed mosses, coarse grasses, etc. The peat next the surface, less advanced in decomposition, is light, spongy and fibrous, of a yellow or light reddish-brown color; lower down it is more compact, of a darker-brown color, and in the lowest strata it is of a blackish brown, or almost a black color, of a pitchy or unctuous feel.

Peat in its natural condition generally contains from 75 to 80 per cent. of water. It sometimes amounts to 85 or 90 per cent. in which case the peat is of the consistency of mire.

When wet peat is milled or ground so that the fibre is broken, crushed or cut, the contraction in drying is much increased by this treatment; and the peat becomes denser, and is better consolidated than when it is dried as it is cut from the bog; peat so prepared is known as condensed peat, and the degree of condensation varies according to the natural heaviness of the peat. So effectively is peat consolidated and condensed by the simple process of breaking the fibres whilst wet, that no merely mechanical force of compression is equal to it.

In the table the elements of peat are presented in two conditions. One perfectly dried into a powder before analyzing and the other with 25 per cent. of moisture.

The value of peat as a fuel of the future is an interesting problem in view of the numerous inroads made upon our great natural coal fields.

TAN.

Tan, or oak bark, after having been used in the process of tanning is burned as fuel. The spent tan consists of the fibrous portion of the bark. Five parts of oak bark produce four parts of dry tan.

STRAW.

COKE, CHARCOAL, PEAT CHARCOAL.

These are similar substances produced by like processes from coal, wood, and peat and they vary in their steam-producing power according to the power of the fuels from which they are produced. The method by which they are made is termed carbonization, which means that all the gases are removed by heat in closed vessels or heaps, leaving only the carbon and the more solid parts like ashes.

LIQUID AND GAS FUELS.

Under this head come petroleum and coal gas, which are obtained in great variety and varying value from coal and coal oil. The heating power of these fuels stands in the front rank, as will be seen by the table annexed.

There are kinds of fuel other than coal, such as wood, coke, sawdust, tan bark, peat and petroleum oil and the refuse from oil. These are all burned with atmospheric air of which the oxygen combines with the combustible part of the fuel while the nitrogen passes off into the chimney as waste.

The combustible parts of coal are carbon, hydrogen and sulphur and the unburnable parts are nitrogen, water and the incombustible solid matters such as ashes and cinder. In the operation of firing under a boiler the three first elements are totally consumed and form heat; the nitrogen, and water in the form of steam, escapes to the flue, and the ashes and cinders fall under the grates.

The anthracite coal retain their shape while burning, though if too rapidly heated they fall to pieces. The flame is generally short, of a blue color. The coal is ignited with difficulty; it yields an intense local or concentrated heat; and the combustion generally becomes extinct while yet a considerable quantity of the fuel remains on the grate.

The dry or free burning bituminous coals are rather lighter than the anthracites, and they soon and easily arrive at the burning temperature. They swell considerably in coking, and thus is facilitated the access of air and the rapid and complete combustion of their fixed carbon.

The method of firing with different sorts of fuel will be treated elsewhere.

AIR.

The engineer’s success in the management of the furnace depends quite as much upon his handling the air in the right mixtures and proportions as it does in his using the fuel—for

1. Although invisible to the eye air is as much a material substance as coal or stone. If there were an opening into the interior of the earth which would permit the air to descend its density would increase in the same manner at it diminishes in the opposite direction. At the depth of about 34 miles it would be as dense as water, and at the depth of 48 miles it would be as dense as quicksilver, and at the depth of about 50 miles as dense as gold.

2. Air is not only a substance, but an impenetrable body; as for example: if we make a hollow cylinder, smooth and closed at the bottom, and put a stopper or solid piston to it, no force will enable us to bring it into contact with the bottom of the cylinder, unless we permit the air within it to escape.

3. Air is a fluid which is proved by the great movability of its parts, flowing in all directions in great hurricanes and in gentle breezes; and also by the fact that a pressure or blow is propagated through all parts and affects all parts alike.

4. It is also an elastic fluid, thus when an inflated bladder is compressed it immediately restores itself to its former situation; indeed, since air when compressed restores itself or tends to restore itself, with the same force as that with which it is compressed, it is a perfectly elastic body.

5. The weight of a column of air one square foot at the bottom is found to be 2156 lbs. or very nearly 15 lbs. to the square inch, hence it is common to state the pressure of the atmosphere as equal to 15 lbs. to the square inch.

It follows from these five points that the engineer must consider air as a positive, although unseen, factor with which his work is to be accomplished.

What air is composed of is a very important item of knowledge. It is made of a mixture of two invisible gases whose minute and inconceivably small atoms are mingled together like a parcel of marbles and bullets—that is while together they do not lose any of their distinctive qualities. The two gases are called nitrogen and oxygen, and of 100 parts or volumes of air 79 parts are of nitrogen and 21 parts of oxygen; but by weight (for the oxygen is the heaviest) 77 of nitrogen and 23 of oxygen.

The oxygen is the part that furnishes the heat by uniting with the coal—indeed without it the process of combustion would be impossible: of the two gases the oxygen is burned in the furnace, more or less imperfectly, and the nitrogen is wasted.

Table of Evaporation.

In order to arrive at the money value of the various fuels heretofore described a method of composition has been arrived at which gives very accurately their comparative worth. The rule is too advanced for this elementary work, but the following results are plainly to be understood, and will be found to be of value.

The way to read this table is as follows: “one lb. coal has an average evaporative capacity of 14.62 lbs. of water,” or

One lb. of peat with one-quarter moisture will evaporate, if all the heat is utilized 7.41 lbs. of water.

In practice but little over half of these results are attained, but for a matter of comparison of the value of one kind of fuel with another the figures are of great value; a boiler burning wood or tan needs to be much larger than one burning petroleum oil.

FIRE IRONS.

The making or production of steam requires the handling of the fuel, more or less, until its destruction is complete, leaving nothing behind in the boiler room, except ashes and clinkers. The principal tools used by the attendant, to do the task most efficiently are: 1. The scoop shovel. 2. The poker. 3. The slice bar. 4. The barrow.

Fig. 1.

[Fig. 1.] represents the regular scoop shovel commonly called “a coal shovel,” but among railroad men and others, known as a locomotive or charging scoop. The cut also represents a regular shovel. Both these are necessary for the ordinary business of the boiler room.

Fig. 2.

In [cut 2] are represented a furnace poker, A, and two forms of the slice bar. They are all made by blacksmiths from round iron, some 7 or 8 feet long and only vary in the form of the end. The regular slice bar is shown in C, [Fig. 2]; and “the dart” a special form used largely on locomotives is shown in B.

The dexterous use of these important implements can merely be indicated in print, as it is part of the trade which is imparted by oral instruction. One “point” in making the slice bar may be mentioned to advantage—the lower side should be perfectly flat so that it may slide on the surface of the grate bars as it is forced beneath the fire—and the upper portion of the edge should be in the shape of a half wedge, so as to crowd upwards the ashes and clinkers while the lower portion slides along.

There is sometimes used in connection with these tools an appliance called a Lazy Bar. This is very useful for the fireman when cleaning a bituminous or other coal fire: it saves both time and fuel as well as steam. It is a hook shaped iron, ingeniously attached above the furnace door, so that it supports the principal part of the weight of the heavy slice bar or poker when being used in cleaning out the fires.

Fig. 3.

Equally necessary to the work of the boiler-room is the barrow shown in cut. There are many styles of the vehicle denominated respectively—the railroad barrow, the ore and stone barrow, the dirt barrow, etc.; but the one represented in [fig. 3] is the regular coal barrow.

In conveying coal to “batteries” of boilers, in gas houses and other suitable situations the portable car and iron track are nearly always used instead of the barrow. In feeding furnaces with saw dust and shavings large iron screw conveyors are frequently employed, as well as blowers—In the handling of the immense quantities of fuel required, the real ingenuity of the engineer in charge has ample opportunity for exercise.

There are also used in nearly all boiler rooms HOES made of heavy plate iron, with handles similar to those shown in the cuts representing the slice bar and poker. A set of two to four hoes of various sizes is a very convenient addition to the list of fire tools; a light garden hoe for handling ashes is not to be omitted as a labor saving tool.

HANDY TOOLS.

Besides the foregoing devices for conducting the preliminary process of the steam generation, the attendant should have close at hand a servicable HAND HAMMER, a SLEDGE for breaking coal and similar work, and A SCREW WRENCH and also a light LADDER for use about the boiler and shafting.

In addition to these there are various other things almost essential for the proper doing of the work of the boiler room,—Fire and Water Pails, Lanterns, Rubber Hose, etc., which every wise steam user will provide of the best quality and which the engineer will as carefully keep in their appointed places ready for instant service.

Fig. 4.

To these familiar tools can be added FILES, LACE CUTTERS, BOILER-FLUE BRUSHES, STOCK and DIES, PIPE-TONGS, SCREW JACKS, VISES, etc., all of which when used with skill and upon right occasion pay a large return on their cost.

THE TOOL BOX.

The complex operations of the boiler room, its emergencies and varying conditions demand the use of many implements which might at first thought be out of place. The following illustrations exhibit some of these conveniences.

Fig. 5.

[Fig. 5], letter A, show the common form of COMPASSES which are made from 3 to 8 inches long. Letter B, illustrates the common steel compass dividers, which are made from 5 to 24 inches in length.

Fig. 6.

In this illustration, A exhibits double, inside and outside Calipers; B, adjustable outside Calipers; C, inside; and D outside, plain calipers.

THE FIRING OF STEAM BOILERS.

The care and management of a steam boiler comprises three things:

1. The preparation, which includes the partial filling with water and the kindling of the fire.

2. The running, embracing the feeding, firing and extinction or banking of the fire.

3. The cleaning out after it has been worked for some time.

To do this to the best advantage, alike to owner and employee, can be learned only by practice under the tuition of an experienced person. The “trick” or unwritten science of the duties of the skillful fireman must be communicated to the beginner, by already experienced engineers or firemen or from experts who have made the matter a special study. Let it be understood that the art of firing cannot be self taught.

The importance of this knowledge is illustrated by a remarkable difference shown in competitive tests in Germany between trained and untrained firemen in the matter of securing a high evaporation per pound of coal. The trained men succeeded in evaporating 11 lbs. of water, as against 6.89 lbs. which was the best that the untrained men could obtain.

It is certain that a poor fireman is a dear man at any price, and that a competent one may be cheap at twice the wages now paid. Suppose, for instance, a man who burns three tons a day is paid $2.00 for such service, and that in so doing he is wasting as little as 10 per cent. If the coal cost $4.50 per ton the loss will be $1.35 per day, or what is equivalent to paying a man $3.35 per day who can save this amount.

The late Chief Engineer of Philadelphia Water Works effected an annual saving to the city of something like $50,000; and recently the weekly consumption of a well established woolen mill was reduced from 71 to 49 tons, a clear saving of 22 tons by careful attention to this point.

It is apparent that any rules or directions which might be given for one system would not apply equally to other forms of boilers and this may be the principal reason that the art is one so largely of personal instruction. Some rules and hints will, however, be given to the beginner, which may prove of advantage in fitting the fireman for an advanced position; or to assure him permanence in his present one.

No two boilers alike. It is said that no two boilers, even though they seemed to be exactly alike—absolute duplicates—ever did the same, or equal service. Every steam boiler, like every steam engine, has an individuality of its own, with which the person in charge has to become acquainted, in order to obtain the best results from it.

The unlikeness in the required care of steam engines which seem to be exactly the same, is still more marked in the different skill and experience demanded in handling locomotive, marine, stationary, portable boilers and other forms of steam generators.

Before Lighting the Fire under the boiler in the morning, the engineer or fireman should make a rapid yet diligent examination of various things, viz.: 1. He should make sure that the boiler has the right quantity of water in it—that it has not run out during the night or been tampered with by some outside party; very many boilers have been ruined by neglecting this first simple precaution. 2. He should see that the safety-valve is in working order; this is done by lifting by rod or hand the valve which holds the weight upon the safety valve rod. 3. He should open the upper gauge-cock to let out the air from the boiler while the steam is forming. 4. He should examine the condition of the grate-bars and see that no clinkers and but few ashes are left from last night’s firing. 5. And finally, after seeing that everything is in good shape, proceed to build the fire as follows:

On Lighting the Fire. When quite certain that everything is in good condition, put a good armful of shavings or fine wood upon the grate, then upon this some larger pieces of wood to form a bed of coals, and then a little of the fuel that is to be used while running. Sometimes it is better to light before putting on the regular fuel, but in any case give it plenty of air. Close the fire doors, and open the ash pit, giving the chimney full draught.

When the fire is well ignited, throw in some of the regular fuel, and when this is burning add more, a little at a time, and continue until the fire is in its normal condition, taking care, however, not to let it burn too freely for fear of injury to the sheets by a too rapid heating.

It is usually more convenient to light the fire through the fire door, but where this cannot be done, a torch may be used beneath the grates, or even a light fire of shavings may be kindled in the ash pit.

At the time of lighting, all the draughts should be wide open.

As soon as the steam is seen to issue from the open upper gauge-cock it is proof that the air is out. It should now be closed and the steam gauge will soon indicate a rise in temperature.

When the steam begins to rise it should next be observed that: 1. All the cocks and valves are in working order—that they move easily. 2. That all the joints and packings are tight.

In the following two cuts are exhibited in an impressive way the difference between proper and improper firing.

Fig. 1.

[Fig. 1] represents the proper mode of keeping an even depth of coal on the grate bars; the result of which will be, a uniform generation of gas throughout the charge, and a uniform temperature in the flues.

Fig. 2.

[Fig. 2] represents a very frequent method of feeding furnaces; charging the front half as high, and as near the door, as possible, leaving the bridge end comparatively bare. The result necessarily is that more air obtains access through the uncovered bars than is required, which causes imperfect combustion and consequent waste.

The duties of the fireman in the routine of the day may thus be summed up:

1st.—Begin to charge the furnace at the bridge end and keep firing to within a few inches of the dead plate.

2d.—Never allow the fire to be so low before a fresh charge is thrown in, that there shall not be at least three to five inches deep of clean, incandescent fuel on the bars, and equally spread over the whole.

3d.—Keep the bars constantly and equally covered, particularly at the sides and the bridge end, where the fuel burns away most rapidly.

4th.—If the fuel burns unequally or into holes, it must be leveled, and the vacant spaces must be filled.

5th.—The large coals must be broken into pieces not bigger than a man’s fist.

6th.—When the ash pit is shallow, it must be the more frequently cleared out. A body of hot cinders, beneath them, overheats and burns the bars.

7th.—The fire must not be hurried too much, but should be left to increase in intensity gradually. When fired properly the fuel is consumed in the best possible way, no more being burned than is needed for producing a sufficient quantity of steam and keeping the steam pressure even.

DIRECTIONS FOR FIRING WITH VARIOUS FUELS.

Firing Boilers Newly Set, etc.—Boilers newly set should be heated up very slowly indeed, and the fires should not be lighted under the boilers for at least two weeks after setting, if it is possible to wait this length of time. This two weeks enables all parts of the mason work to set gradually and harden naturally; the walls will be much more likely to remain perfect than when fires are lighted while the mortar is yet green.

When fire is started under a new boiler the first time, it should be a very small one, and no attempt should be made to do more than moderately warm all parts of the brick work. A slow fire should be kept up for twenty-four hours, and on the second day it may be slightly increased. Three full days should elapse before the boiler is allowed to make any steam at all.

When the pressure rises, it should not be allowed to go above four or five pounds, and the safety valve weight should be taken off to prevent any possibility of an increase. Steam should be allowed to go through all the pipes attached for steam, and blow through the engine before any attempt is made to get pressure on them. The object of all these precautions and this care is to prevent injury by sudden expansion, which may cause great damage.

Firing with Coke.

Coke, in order to be completely consumed, needs a greater volume of air per pound of fuel than coal. Theoretically it needs from 9 to 10 lbs. of air to burn a pound of coal, and 12 to 13 lbs. of air to burn a pound of coke.

Coke, therefore, requires a more energetic draft, which is increased by the fact that it can only burn economically in a thick bed. It is also necessary to take into account the size of the pieces.

The ratio between the heating and grate surface should be less with coke than with coal; that is to say, the grate should be larger.

The difference amounts to about 33 per cent. In fact, about 9³⁄₄ lbs. of coke should be burned per hour on each square foot of grate area, while at least 14¹⁄₂ lbs. of coal can be burned upon the same space.

The high initial temperature which is developed by the combustion of coke requires conducting walls. Therefore the furnace should not be entirely surrounded by masonry; and the plates of the boiler should form at least the crown of the fire-box. In externally fired boilers, the furnace should be located beneath and not in front of the boiler. Internal fire-boxes may be used, but the greatest care should be exercised to avoid any incrustation of the plates, and in order that this may be done, only the simplest forms of boilers should be used. With coke it is not essential that long passages should be provided for the passage of the products of combustion, since the greater part of the heat developed is transmitted to the sheets in the neighborhood of the furnace.

Since coke contains very little hydrogen, the quick flaming combustion which characterizes coal is not produced, but the fire is more even and regular. And, finally, the combustion of coal is distinguished by the fact that in the earlier phases there is usually an insufficiency of air, while in the last there is no excess.

The advantage of coke over raw soft coal as a fuel is that otherwise useless slack can be made available by admixture in its manufacture, and especially that it can be perfectly and smokelessly burnt without the need of skilled labor. And we cannot doubt that the public demand for a clear and healthy atmosphere will finally result in the almost complete substitution of coke fuel for soft lump coal.

Sixteen Steam Boilers in a large mill in Massachusetts of 54 and 60 inches in diameter are fired as follows:

There are three separate batteries; one of five boilers, one of eight and one of three. Each boiler is fired every five minutes. There are two firemen for the battery of twelve and one for each of the others. A gong in each fire-room is operated by electricity in connection with a clock. The duty of the fireman is this, that when the gong strikes he commences at one end of his fire-room and fires as rapidly as possible, opening one-half of each furnace door. The coal is thrown only on one-half of the grate space as he rapidly fires each boiler, the other half is covered at the next sounding of the gong. The old style of straight grate is used. The fires are kept six inches thick or a little thicker. No slicing is done. It is, of course, to be understood that the firemen arrange the quantity of coal fired according to the apparent necessity of the case. Bituminous coal is used, and it is broken into small pieces, so as to distribute well. Accurate account is kept of the quantity of coal used and the engines are frequently indicated.

Twenty Horse Power.—An old engineer says the way he handled his boiler of this size, burning 800 lbs. of screenings per day, is as follows:

My method is to run as heavy a fire as my fire-box will allow to be kept under the bridge wall, and not to disturb it more than once in a ten-hours run, then clean out with care and as speedily as possible, dress light and let it come up and get ready to bank. In banking I make sure to have an even fire, as deep as the bridge wall will allow. Then I shut my dampers and let it lie. In the morning I open and govern by the dampers. I do not touch my fire until 3.30 or 4 o’clock in the afternoon, and then proceed to clean as before.

Firing with Coal Tar.—The question of firing retort benches with tar instead of coke has engaged the attention of gas managers for many years, and various modes have been adopted for its management. The chief difficulty has been in getting a constant flow of tar into the furnace, uninterrupted by stoppages caused by the regulating cock or other appliance not answering its purpose and by the carbonizing of the tar in the delivery pipe, thus choking it up and rendering it uncertain in action. To obviate these difficulties various plans have been resorted to, but the best means for overcoming them are thus described; fix the tar supply tank as near the furnace to be supplied as convenient, and one foot higher than the tar-injector inlet. A cock is screwed into the side of the tank, to which is attached a piece of composition pipe ³⁄₈-inch in diameter, ten inches long. To this a ¹⁄₂-inch iron service pipe is connected, the other end of which is joined to the injector. By these means it is found that at the ordinary temperature of the tar well (cold weather excepted) four gallons of tar per hour are delivered in a constant steam into the furnace. If more tar is required, the piece of ³⁄₈-inch tube must be shortened, or a larger tube substituted, and if less tar is required it must be lengthened. The risk of stoppage in the nozzle of the injector is overcome by the steam jet, which scatters the tar into spray and thus keeps everything clear. Trouble being occasioned by the retorts becoming too hot, in which case, on shutting off the flow of tar for a while, the tar in the pipe carbonized and caused a stoppage, a removable plug injector is fitted and ground in like the plug of a cock, having inlets on either side for tar and steam. This plug injector can be removed, the tar stopped in two seconds and refixed in a similar time. The shell of the injector is firmly bolted to the top part of the door frame. The door is swung horizontally, having a rack in the form of a quadrant, by which it is regulated to any required height, and to admit any quantity of air.

Firing with Straw.—The operation of burning straw under a boiler consists in the fuel being fed into the furnace only as fast as needed. When the straw is handled right, it makes a beautiful and very hot flame and no smoke is seen coming from the stack. The whole secret of getting the best results from this fuel is to feed it into the furnace in a gradual stream as fast as consumed. When this is done complete combustion is the result. A little hole maybe drilled in the smoke-box door, so that the color of the fire can be seen and fire is handled accordingly. When the smoke comes from the stack the color of the flame is that of a good gas jet. By feeding a little faster the color becomes darker and a little smoke comes from the stack; feeding a little faster the flame gets quite dark and the smoke blacker; faster still, the flame is extinguished, clouds of black smoke come from the stack, and the pressure is falling rapidly.

Firing with Oil.—Great interest is now manifested in the use of oil as fuel. There are various devices used for this purpose, most of them depending upon a steam jet to atomize the oil, or a system of retorts to first heat the oil and convert it into gas, before being burned.

Another method in successful operation is the use of compressed air for atomizing the oil—air being the element nature provides for the complete combustion of all matter. The cleanliness of the latter system and its comparative freedom from any odor of oil or gas and its perfect combustion, all recommend it. Among the advantages claimed for the use of oil over coal are 1, uniform heat; 2, constant pressure of steam; 3, no ashes, clinkers, soot or smoke, and consequently clean flues; 4, uniform distribution of heat and therefore less strain upon the plates.

Firing on an Ocean Steamer like the “Umbria.”—The men come on in gangs of eighteen stokers or firemen and twelve coal passers, and the “watch” lasts four hours. The “Umbria” has 72 furnaces, which require nearly 350 tons of coal a day, at a cost of almost $20,000 per voyage. One hundred and four men are employed to man the furnaces, and they have enough to do. They include the chief engineer, his three assistants, and ninety stokers and coal passers.

The stoker comes to work wearing only a thin undershirt, light trousers and wooden shoes. On the “Umbria” each stoker tends four furnaces. He first rakes open the furnaces, tosses in the coal, and then cleans the fire; that is, pries the coal apart with a heavy iron bar, in order that the fire may burn freely. He rushes from one furnace to another, spending perhaps two or three minutes at each. Then he dashes to the air pipe, takes his turn at cooling off, and waits for another call to his furnace, which comes speedily. When the “watch” is over, the men schuffle off, dripping with sweat from head to foot, through long, cold galleries to the forecastle, where they turn in for eight hours. Four hours of scorching and eight hours sleep make up the routine of a fireman’s life on a voyage.

The temperature is ordinarily 120°, but sometimes reaches 160°; and the work is then terribly hard. The space between the furnaces is so narrow that when the men throw in coal they must take care when they swing back their shovels, lest they throw their arms on the furnace back of them.

In a recent trial of a government steamer the men worked willingly in a temperature of 175°, which, however, rose to 212° or the heat of boiling water. The shifts of four hours were reduced to 2 hours each, but after sixteen men had been prostrated, the whole force of thirty-six men refused to submit to the heat any longer and the trial was abandoned.

There is no place on ocean or land where more suffering is inflicted and endured by human beings than in these h——holes, quite properly so called; it is to be hoped that the efforts towards reform in the matter will not cease until completely successful.

Firing of Sawdust and Shavings.—“The air was forced into the furnace with the planer shavings at a velocity of about 12 feet per second, and at an average temperature of about 60 degrees Fahrenheit. The shavings were forced through a pipe 12 inches in diameter, above grate, into the combustion chamber. The pipe had a blast gate to regulate the air in order to maintain a pressure in the furnace, which a little more than balanced the ascending gases in the funnel or chimney. All the fireman had to do was to keep the furnace doors closed and watch the water in the gauges of his boiler. The combustion in the furnace was complete, as no smoke was visible. The shavings were forced into the combustion chamber in a spray-like manner, and were caught into a blaze the moment they entered. The oxygen of the air so forced into the furnace along with the shavings gave full support to the combustion. The amount of shavings consumed by being thus forced into the furnace was about fifty per cent. less than the amount consumed when the fireman had to throw them in with his shovel.”

Fig. 9.

It is an important “point” when burning shavings or sawdust with a blast, to keep the blower going without cessation, as there have been disastrous accidents caused by the flames going up the shutes, thence through the small dust tubes leading from the bin to the various machines.

Fig. 10.

In firing “shavings” by hand it is necessary to burn them from the top as otherwise the fire and heat are only produced when all the shavings are charred. To do this, provide a half-inch gas pipe, to be used as a light poker; light the shaving fire, and when nearly burned take the half-inch pipe and divide the burning shavings through the middle, banking them against the side-walls, as shown in Fig. 9. Now feed a pile of new shavings into the centre on the clean grate bars, as shown in Fig. 10, and close the furnace doors. The shavings will begin to burn from above, lighted from the two side fires, the air will pass through the bars into the shavings, where it will be heated and unite with the gas, making the combustion perfect, generating heat, and no smoke, and the fire will last much longer and require not half the labor in stoking.

FIRING A LOCOMOTIVE.

This figure exhibits the interior of the furnace of a locomotive engine, which varies greatly from the furnace of either a land or marine boiler. This difference is largely caused by the method of applying the draught for the air supply; in the locomotive this is effected by conducting the exhaust steam through pipes from the cylinders to the smoke-box and allowing it to escape up the smoke stack from apertures called exhaust nozzles; the velocity of the steam produces a vacuum, by which the products of combustion are drawn into the smoke-box with great power and forced out of the smoke stack into the open air.

To prevent the too quick passage of the gases into the flues an appliance called a fire brick arch has been adopted and has proved very efficient. In order to be self supporting it is built in the form of an arch, supported by the two sides of the fire box which serve for abutments. The arch has been sometimes replaced by a hollow riveted arrangement called a water table designed to increase the fire surface of the boiler.

Firing a Locomotive.—No rules can possibly be given for firing a locomotive which would not be more misleading than helpful. This is owing to the great variations which exist in the circumstances of the use of the machine, as well as the differences which exist in the various types of the locomotive.

These variations may be alluded to, but not wholly described. 1. They consist of the sorts of fuel used in different sections of the country and frequently on different ends of the same railroad; hard coal, soft coal, and wood all require different management in the furnace. 2. The speed and weight of the train, the varying number of cars and frequency of stopping places, all influence the duties of the fireman and tax his skill. 3. The temperature of the air, whether cold or warm, dry weather or rain, and night time and day time each taxes the skill of the fireman.

Hence, to be an experienced fireman in one section of the country and under certain circumstances does not warrant the assurance of success under other conditions and in another location. The subject requires constant study and operation among not only “new men” but those longest in the service.

More than in any other case to be recalled, must the fireman of a locomotive depend upon the personal instruction of the engineer in charge of the locomotive.

Firing with Tan Bark.—Tan bark can be burned upon common grates and in the ordinary furnace by a mixture of bituminous screenings. One shovel full of screenings to four or five of bark will produce a more economical result than the tan bark separate, as the coal gives body to the fire and forms a hot clinker bed upon which the bark may rest without falling through the spaces in the grate bars, and with the coal, more air can be introduced to the furnace.

The above relates to common furnaces, but special fire boxes have been recently put into operation, fed by power appliances, which work admirably. The “point” principally to be noted as to the efficacy of tan bark as a fuel, is to the effect, that like peat, the drier it is the more valuable is it as a fuel.

POINTS RELATING TO FIRING.

The Process of Boiling. Let it be remembered that the boiling spoken of so often is really caused by the formation of the steam particles, and that without the boiling there can be but a very slight quantity of steam produced.

While pure water boils at 212°, if it is saturated with common salt, it boils only on attaining 224°, alum boils at 220°, sal ammoniac at 236°, acetate of soda at 256°, pure nitric acid boils at 248°, and pure sulphuric acid at 620°.

On the First Application of Heat to water small bubbles soon begin to form and rise to the surface; these consist of air, which all water contains dissolved in it. When it reaches the boiling point the bubbles that rise in it are principally steam.

In the case of a new plant, or where the boiler has some time been idle it is frequently advisable to build a small fire in the base of the chimney before starting the boiler fires. This will serve to heat the chimney and drive out any moisture that may have collected in the interior and will frequently prevent the disagreeable smoking that often follows the building of a fire in the furnace.

Always bear in mind that the steam in the boilers and engines is pressing outward on the walls that confine it in every direction; and that the enormous forces you are handling, warn you to be careful.

When starting fires close the gauge cocks and safety valve as soon as steam begins to form.

Go slow. It is necessary to start all new boilers very slowly. The change from hot to cold is an immense one in its effects on the contraction and expansion of the boiler, the change of dimension by expansion is a force of the greatest magnitude and cannot be over-estimated. Leaks which start in boilers that were well made and perfectly tight can be attributed to this cause. Something must give if fires are driven on the start, and this entails trouble and expense that there is no occasion for. This custom applies to engines and steam pipes as well as to boilers. No one of any experience will open a stop valve and let a full head of live steam into a cold line of pipe or a cold engine.

To preserve the grate bars from excessive heat, when first firing a boiler, it is well to sprinkle a thin layer of coal upon the grates before putting in the shavings and wood for starting the fire. This practice tends greatly to prolong the life of the grate-bars.

The fuel should generally be dry when used. Hard coal, however, may be dampened a little to good advantage, as it is then less liable to crowd and will burn more freely.

Air, high temperature and sufficient time are the principal points in firing a steam boiler.

In first firing up make sure that the throttle valve is closed, in order that the steam first formed may not pass over into the engine cylinder and fill it with water of condensation. If the throttle valve leak steam it should be repaired at the first opportunity.

Keep all heating surfaces free from soot and ashes.

Radiant rays go in all directions, yet they act in the most efficient manner when striking a surface exactly at a right angle to their line of movement. The sides of a fire-box are for that reason not as efficient as the surface over the fire, and a flat surface over the fire is the best that can be had, so far as that fact alone is concerned.

When combustion is completed in a furnace, then the balance of the boiler beyond the bridge wall can be utilized for taking up heat from the gases. The most of this heat has to be absorbed by actual contact; thus by the tubes the gases are finally divided, allowing that necessary contact.

Combustion should be completed on the grates for the reason that it can be effected there at the highest temperature. When this is accomplished, the fullest benefit is had from radiant heat striking the bottom of the boiler—it is just there that the bulk of the work is done.

There must necessarily be some waste of heat by its passing up the chimney to maintain draft. It is well to have the gases, as they enter the chimney, as much below 600 deg. F. (down to near the temperature of the steam) as you can and yet maintain perfect combustion.

Every steam engine has certain well-defined sounds in action which we call noises, for want of a better term, and it is upon them and their continuance that an engineer depends for assurance that all is going well.

This remark also applies to the steam boiler, which has, so to speak, a language of its own, varying in volume from the slight whisper which announces a leaking joint to the thunder burst which terribly follows a destructive explosion. The hoarse note of the safety-valve is none the less significant because common.

The dampers and doors to the furnace and ash-pit should always be closed after the fire has been drawn, in order to keep the heat of the boiler as long as possible.

But the damper must never be entirely closed while there is fire on the grate, as explosions dangerous in their character might occur in the furnace from the accumulated gases.

Flues or tubes should often be swept, as soot, in addition to its liability to becoming charged with a corroding acid, is a non-conductor of heat, and the short time spent in cleaning them will be repaid by the saving of labor in keeping up steam. In an establishment where they used but half a ton of bituminous coal per day, the time of raising steam in the morning was fifty per cent. longer when the tubes were unswept for one week than when they were swept three times a week.

Smoke will not be seen if combustion is perfect. Good firing will abate most of the smoke.

Coals, at the highest furnace temperature, radiate much heat, whereas gases ignited at and beyond the bridge wall radiate comparatively little heat—it is a law in nature for a solid body highly heated to radiate heat to another solid body.

Dry and Clean is the condition in which the boiler should be kept, i.e., dry outside and clean both inside and out.

To haul his furnace fire and open the safety valve before seeking his own safety or the preservation of property, is the duty of the fireman in the event of fire threatening to burn a whole establishment.

Many, now prominent, engineers have made their first reputation by remembering to do this at a critical time.

When Water is Pumped into the boiler or allowed to run in, some opening must be given for the escape of the contained air; usually the most convenient way is to open the upper gauge cock after the fire has been lighted until cloudy steam begins to escape.

In a summary of experiments made in England, it is stated that:—

“A moderately thick and hot fire with rapid draft uniformly gave the best results.

“Combustion of black smoke by additional air was a loss.

“In all experiments the highest result was always obtained when all the air was introduced through the fire bars.

“Difference in mode of firing only may produce a difference of 13 per cent. (in economy).”

The thickness of the fire under the boiler should be in accordance with the quality and size of the fuel. For hard coal the fire should be as thin as possible, from three to six inches deep; when soft coal is used, the fire should be thicker, from five to eight inches deep.

If it is required to burn coal dust without any change of grates, wetting the coal is of advantage; not that it increases its heat power, but because it keeps it from falling through the grates or going up the chimneys. The same is true of burning shavings; by watering they are held in the furnace, and the firing is done more easily and with better results.

Stirring the Fire should be avoided as much as possible; firing should be performed evenly and regularly, a little at a time, as it causes waste fuel to disturb the combustion and by making the fuel fall through the grates into the ash pit; hence do not “clean” fires oftener than absolutely necessary.

The slower the velocity of the gases before they pass the damper, the more nearly can they be brought down to the temperature of the steam, hence with a high chimney and strong draft the dampers should be kept nearly closed, if the boiler capacity will permit it.

No arbitrary rule can be laid down for keeping fires thick or thin. Under some conditions a thin fire is the best, under others a thick fire gives best economy. This rule, however, governs either case: you must have so active a fire as to give strong radiant heat.

One of the highest aims of an expert fireman should be to keep the largest possible portion of his grate area in a condition to give great radiant heat the largest possible part of the day—using anthracite coal by firing light, quick and often, not covering all of the incandescent coals. Using bituminous coal, hand firing, by coking it very near the dead plate, allowing some air to go through openings in the door, and by pushing toward the bridge wall only live coals—when slicing, to open the door only far enough to work the bar; this is done with great skill in some cases.

Regulating the Draft.—This should be done so as to admit the exact quantity of air into the furnace, neither too much nor too little. It should be remembered that fuel cannot be burned without air and if too much air is admitted it cools the furnace and checks combustion. It is a good plan to decrease the draft when firing or cleaning out, by partly closing the damper or shutting off the air usually admitted from below the grates; this is to have just draft enough to prevent the flame from rushing out when the door is opened.

By luminous flame is generally meant that which burns with a bright yellow to white color. All flame under a boiler is not luminous, sometimes the whole or a part of it will be red or blue. The more luminous the flame, that is to say, the nearer white it is, the better combustion.

To determine the temperature of a furnace Fire the following table is of use. The colors are to be observed and the corresponding degrees of heat will be approximately as follows:

That is to say, when the furnace is at a “white heat” the heat equals 2,400 degrees Fahrenheit, etc.

Another method of finding the furnace heat is by submitting a small portion of a particular metal to the heat.

FOAMING IN BOILERS.

The causes are—dirty water, trying to evaporate more water than the size and construction of the boiler is intended for, taking the steam too low down, insufficient steam room, imperfect construction of boiler, too small a steam pipe and sometimes it is produced by carrying the water line too high.

Too little attention is paid to boilers with regard to their evaporating power. Where the boiler is large enough for the water to circulate, and there is surface enough to give off the steam, foaming never occurs.

As the particles of the steam have to escape to the surface of the water in the boiler, unless that is in proportion to the amount of steam to be generated, it will be delivered with such violence that the water will be mixed with it, and cause foaming.

For violent ebullition a plate hung over the hole where the steam enters the dome from the boiler, is a good thing, and prevents a rush of water by breaking it, when the throttle is opened suddenly.

In cases of very violent foaming it is imperative to check the draft and cover the fires.

The steam pipe may be carried through the flange six inches into the dome—which will prevent the water from entering the pipes by following the sides of the dome as it does.

A similar case of priming of the boilers of the U. S. Steamer Galena was stopped by removing some of the tubes under the smoke stack and substituting bolts.

Clean water, plenty of surface, plenty of steam room, large steam pipes, boilers large enough to generate steam without forcing the fires, are all that is required to prevent foaming.

A high pressure insures tranquillity at the surface, and the steam itself being more dense it comes away in a more compact form, and the ebullition at the surface is no greater than at a lower pressure. When a boiler foams it is best usually to close the throttle to check the flow, and that keeps up the pressure and lessens the sudden delivery.

Too many flues in a boiler obstruct the passage of the steam from the lower part of the boiler on its way to the surface—this is a fault in construction.

An engineer who had been troubled with priming, finally removed 36 of the tubes in the centre of the boiler, so as to centralize the heating effect of the fire, thereby increasing the rapidity of ebullition at the centre, while reducing it at the circumference. The effect of the change was very marked. The priming disappeared at once. The water line became nearly constant, the extreme variation being reduced to two inches.