Oil Burning and Oil-Burning Equipment in Industrial and Chemical Plants

of oil daily. ~~~h ofthis that now not only does the years, the present supply being more than ample. Most oil is being burned in direct supply of oil...
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January, 1925

INDUSTRIAL A N D ENGINEERING CHEMISTRY

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Oil Burning and Oil-Burning Equipment in Industrial and Chemical Plants’ By W. F. Schaphorst 45 ACADEMY ST., NEWARK, N. J.

ANY chemists probably do not know that a t the sorb as much of the heat.as possible. If the boiler is covered present time there is an over-production of oil in with soot or filled with scale, it is surely no fault of the burner the United States and that as a result its price is low. and it is not likely that the boiler will perform any better It is predicted by experts that the low price will continue with oil for fuel than with coal. The boiler and tubes should for a number of years, making oil burning more economical always be kept clean, inside and out. It appears that oil was first used for fuel by the Russians, than it has been in the past and enabling it to compete with other combustibles. over sixty years ago, but until comparatively recently it I n the newspapers we frequently read scare heads about has made but little headway. Now, however, according to Henry L. Doherty, we are the dwindling supply of oil. But new fields are continuburning 1,000,000 barrels Oil promises to compete seriously with coal for many of oil daily. ~~~h ofthis ally being discovered, so years, the present supply being more than ample. Most oil is being burned in direct that now not only does the chemical industries are essential industries; consequently, with coal, and supply of oil meet the dethan in case of governmental regulation of oil consumption the it is being done with greater mand but it meets it. prices have chemical industries would not be the first to be affected. economy than with coal. It Oil is now as safe as coal. Some city ordinances are too was natural that the first dropped considerably since severe. Carefully compiled data show that oil as comoil burned was ordinary pre-war d a y s , whereas pared with coal has advantages far outweighing any discrude oil, ~~~l oil was prices of most other modities have increased. , advantages. practically unknown sixty There are two broad classes of oil burners: (1) steam jet years ago. ~h~ burning of With the drop in the consumption has increased, or air jet and (2) mechanical atomizing. The advantages crude oil has been gradually but nevertheless, contrary and disadvantages of both classes are given. Shape and abandoned, however, becombinations of openings in the various burners appear cause of its greater danger. to usual under to make little, if any, difference in burner efficiency. Data It has a considerably lower similar circumstances, oil are included on the heating of oil, furnace volume reflash point than fuel oil. prices have continued to drop. one hundred and quired, current prices of oil, etc., and a few typical burners As a~ chemists doubtless know, fuel oil is the residue eighty million barrels of are of crude oil after removing gasoline were used by motor cars alone during 1923. Twenty years ago it would have the lighter products, such as gasoline. been considered impossible to supply that much gasoline a t At present the great demand for gasoline is of advantage any price. to the industrial plant owner, as because of this, oil fuel is Because of this growth in production it can now be safely both cheaper and safer. Concerning the safety of oil burning said that even purchasers of motor cars need fear no cessation there is practically nothing to fear today. The one-time of oil supply, and prospective users of fuel oil in chemical hazard has been removed through distillation, study, exand industrial plants need no longer ask each other the usual perimentation, and improvement. I n general, it might be questions, “Will it pay us to convert over to oil burning? said, of course, that the more volatile the oil the greater the Will the supply of oil be exhausted before we get our invest- danger. There are few combustibles that are more volatile ment back?” Those who have made a study of the matter than gasoline; yet every chemist knows that even gasoline declare that the supply of oil is ample for hundreds of years. can be used for heating with the utmost safety when properly There are fifteen million automobiles in the United States, stored and fed to the furnace, and it can be burned at least all of them using as much gasoline as they want. If re- as safely as it is used in automobiles. Nearly all cities now strictions are ever to be made anywhere, gasoline supply have ordinances governing oil burning which makes it deto the automobile field will surely be curtailed before the cidedly safe. In fact, some cities have gone entirely too far essential industries are touched. The chemical industry is, with their codes, making them unnecessarily severe and too of course, an essential industry. expensive. There is no doubt in the mind of the writer that Oil is surely far superior to poor coal. The writer knows many codes will be simplified in the future, bringing oil of one instance where two 360-horsepower boilers were fired burning within the economic reach of many chemical and with poor coal. Difficulty was experienced in keeping the industrial plants that are now using coal and other fuels. pressure up to the proper point. After changing over to It is not always easy to compare the cost of oil with the oil burning the entire load is now carried with one boiler and cost of coal, because of the many factors that must be conthere is no difficulty whatever with the pressure. sidered. Thus, to arrive at the actual cost of oil “in the furWhere oil burners are to be used under boilers, however, nace,” the following items usually enter: purchase price, the writer wishes to caution owners and officials that there freight, demurrage, trucking, unloading and pumping, storage, is such a thing as over-enthusiasm for oil burning. Oil pumping to burner system, possible leakage or other losses, burning cannot cure all ills. An oil burner cannot improve heating in burner system, maintenance, air or steam for coma boiler in the least. All a good burner can do is to improve bustion, interest and depreciation on entire outlay; insurance combustion-generate more heat in the furnace per dollar. and boiler room labor. Similarly, when computing the cost After tjhe heat is generated the duty of the boiler is to ab- of coal all items involved in getting the coal “into the furnace” must be included. An approximate rule, easy to re1 Received November 8, 1924.

INDUSTRIAL AND ENGINEERING CHEMISTRY

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member, which is used by some engineers, is this: “Divide the cost of coal in dollars per long ton (2240 pounds) by 2. If the result is greater than the cost of oil in cents per gallon i t will pay to burn oil.” The seasoned chemist will not depend entirely upon such a rule, however, for reasons that are obvious. At the time of reading proof, the following maximum prices for fuel oils were quoted throughout the country, according to the December 4 issue of the Oil and Gas Journal:

Vol. 17, No. 1

is used, and, if mechanical draft is required, less power suffices for oil as compared with coal. The cost of removing ashes and the investment in equipment for ash handling are saved. A further saving as compared with the use oi coal is to be found in the payroU. A prominent burner manufacturer states that with oil burners two men can do the firing

These figures do not agree with all prices quoted by Power, issue of December 2, which are as follows: St. Louis District ... .%1.95 Dallas D i r f r i ~ 1 .... , . 1 . 1 5

~ P X per . hbl. mux. per bbl. Piftvhureh District ... 11.05% mnx. per sal. Cincinnati Uistrict.. 0.05% =SI. per gal. Philadelphia District 2.15 =AX. per bbl. nortonmstriet.. , . . 0.05% max. per (*I. New York District.. 0 05 _ax. per gal.. f.

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b. Bayonne

There is not a great difference in heat values of fuel oils; 18,500 B. t. u. per pound is the average value. For example, one grade of oil weighing 350 pounds per barrel has a heat value of 18,350 B. t. u. per pound, while another grade weighing 341 pounds per barrel has a heat value of 18,620 B. t. u. per pound. Chemists and industrial plant omers and engineers are naturally interested in both the advantages and disadvantages of oil burning. AU sides should be carefully considered before making any drastic and expensive alterations in a plant.

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which with coal would probably require nine men. A few pumps do away with a large number of stokers, ash handlers, etc. After adjustments are once made, the human factor is less important than in coal firing, and because many highgrade engineers prefer oil burning to coal it is often possible to obtain a better engineer at the salary paid. There is less waste heat in oil-burning than in coal-burning plants, for where coal is burned hot ashes with some live coals drop through the grate, carrying heat with them to the Advantages of Oil Burning ash pit. There is no corresponding loss in oil burning. There is seldom a necessity for opening furnace doon, and conse Compared with other fuels, oil has a number of distinct quently the sudden inrush of cold air with temporary loss advantages which far outweigh its disadvantages. A boiler due to excess of air is not met in oil-fired furnaces. can be put iuto operation more quickly if an oil burner is Improved combustion is obtained with oil firing because used than if coal is the fuel. In steel foundry furnaces, in the air is controlled more easily by means of automatic distillation plants, and similar installations, this speed of damper regulat,ion, less smoke is formed because combustion getting under way is adrantageous. Similarly, should it is usually more complete, and less air is required with a conbecome necessary to shut down bhe plant, the heat may be sequent diminution in heat loss up the stack. One pound shut offinstantly-as, for example, in the case of tube rup- of coal requires approximately 18 pounds of air, whereas one ture, overburning, or other difficulties. Where the load is pound of oil requires but 16 pounds of air. Further, the cleaner heating surface of the boiler offers less resistance to heat transmission, resnlting in higher heating efficiency. Where boilers are equipped with soot cleaners, less steam is consumed for their operation, since the tubes do not need to be cleaned so frequently. This effects a further saving in the cost of labor for operating the soot cleaners. Where cleanliness is important, oil burning has an advantage because of the absence of coal and ash dust, this benefit being shared by the neighborhood over which no objectionable residues such as soot and ashes are distributed. .I A saving is also made in installation costs. The smaller FIG.I-A VALVEN a r c n S r a a o ~ r m s o u sCONTROLS ~~ TBE OIL FUEL amount of air used makes possible smaller chimneys, and in *NO THB A T I O ~ ~ ~ Z AOSNT. IN= A~TEX O ~ c eOBIAININCTHE PPIDPER new construction work this may mean an appreciable reducPROPDBfION ob‘ S T E A M O R A m TCIOm THI? MAx:IPuLI\TION olr A SixCLa tion in first costs. The greater boiler output obtainable VllLvB MAINI(&INSTHAT Riirio may even save the cost of an additional boiler, some users variable, fuel oil enables the boilers to take care of such having found that the boiler output may be increased as much sudden emergencies, and where uniform steam pressure is as 50 per cent with proper oil burners. It is possible to inimportant, such pressures are more easily obtained with oil stal oil burners in almost any position-horizontal, vertical, than with coal. Peak loads are more easily maintained and or oblique-a great adrantage in installation. higher heat cificiencies are possible. The cost of maintenance is an important item, and beIt is sometimcs necrssary to “pull” coal fires, which is cause of the absence of vibration due to conveyors, stokers, neither necessary nor possible where oil is burned. The doors, slice bars, shaking pates, etc., there is less wear and costs and losses due to banking fires are obviated Nhere oil tear on the equipment and a consequent saving in replace-

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INDUSTRIAL A N D ENGINEERING CHEMISTRY

January, 1925

ment. Moreover, much of the apparatus required for coal firing need not be installed at all. Since no firing tools are needed and there are no clinkers to be removed, there is less damage to furnace linings, while with more uniform heat c r o w sheets and tubes escape the damage often caused where coal is used for fuel. There is practically no wear and tear on oil-firing equipment, and because fire doors need not be frequently opened, furnaces and boilers are saved the strains caused by the inrush of cold air, and give longer service. Finally, there are advantages in the storage of fuel. No pulverizing and therefore no pulverizing machinery is required. Since oil does not pulverize or form dust, danger of dust explosion does not exist. The oil suffers no diminution in heating value, slacking, or other deterioration in storage. Screening operations are saved. Storage space is saved, since oil requires about one-half the space occupied by coal of the same heating value. Oil is not subject to spontaneous combustion, nor is there danger from dust explosion. On the average, oil weighs 25 per cent less than coal of equal heating value or, to state it differently, possesses 35 per cent more heating value pound for pound. Disadvantages of Oil Burning

Although the points which may be made against oil burning comprise a shorter list than the advantages, they should be given equally careful study, for one of them may easily counterbalance several in the longer list. The unreasonable laws and stringent ordinances governing the storage and burning of oil in some of our cities often make its use more expensive than that of coal. The storage of oil is neither cheap nor simple. It cannot be dumped upon the ground and stored without special facilities, as can coal,fand-the first cost of oil storage tanks is generally greater

mechanical stokers is less than'that for oil feeding, and the steam jets used in oil combustion make that operation more noisy than the combustion of coal. Oil burners sometimes give trouble due to carbonization, overheating, clogging, and mechanical difficulties. I n the purchase of fuel, the consumer is able to buy coal on contracts extending over a long period of time, whereas similar contracts for oil are not yet so readily obtainable. Care must be observed in putting dampers on oil-fired boilers. Should the fire become extinguished an explosive gas may be formed within the furnace which may be ignited by the hot sidewalls. Moreover, if the burner valves leak after being shut off the hot side brick work may cause dangerous explosive gases. These dangers do not exist with coal. Too few present-day firemen realize what concentrated power is locked up in a gallon of fuel oil and for that reason inaccuracy or carelessness on the part of the operators is liable to cause a greater and more complete loss of fuel in a given period of time than could ever happen with the use of coal. It therefore behaoves the man who is paying the bills or the executive in charge of operation to use equipment that uses just the right amount of oil all the time. The regulating device shown in Fig. 1 is designed to take care of one of these conditions. With this valve it is possible t o train a lower rated fireroom force. Once the valve is set for the desired fire, by an experienced foreman, its load can be reduced or increased a t will by the simple operation of manipulating a single control wheel of the valve. Kinds of Oil Burners

Before changing over to oil burners all details should be carefully considered. There are vast differences in burners. A type that will give excellent service in one furnace will not

I BROKEN UP

I - BURNER TIP 2- EXTENSION NIPPLE 3 - %"% I ' REDUCER 4- MIXING CHAMBER 5 - OIL BREAKER FIG.3 - c R O S S

S E C T I O N OF A

BURNERI N

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- OIL

BY PFXSSURE

BREAKER PLUG

7 - OIL BREAKER N\PPiE 8 - BURNER HEAD

II - STUFFING BOX NUT 12- PACKING 13 - PACKING DISC 14 - STEAM BY-PASS VQ#e IS VAiVE HANDLE

9 - U N l o N NUT IO- UNION NIPPLE W H I C H MIXINGTAKES P L A W INSIDE. N O T 5 T H E MANYBAFFLES IN FOR MAKING ATOMIZING AND MIXINGCOMPLETE

than the first cost of coal bins. Tank wagons and tank cars are necessary for the handling of oil, whereas coal can be hauled in almost any vehicle. There may be some evaporation from oil in storage, a disadvantage not shared by coal. Coal need not be preheated, whereas oil must be before feeding to the burners. The power required for operating

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THE BURNER DESIGNED

do well in another unless the conditions are right. Burners are on the market that will take care of different grades of oil, such as Mexican crude, tar, or fuel oils. In other words, they will take care of oils of almost any gravity. Burners are divided into two broad classes: (1) steam jet or air jet and (2) mechanical atomizing. I n reality both

INDUSTRIAL AND ENGir,VEERING CHEMISTRY

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should be called “atomizers” rather than burners, but since “burners” is the usual name they are so called throughout this article. Naturally, the burner that produces a long, high-velocity spray wiU produce a long flame and the furnace should he lone enoueh so that all oil is comnletelv burned before touchigg thelfurnace walls. If the & n e ; creates a wide spray the furnace must be wide. If the spray is conical the lateral dimensions of the furnace must be sufficient to accommodate it. If the furnace is an old one, or already built, burners must he selected that will fit the furnace, because it may be impossihle or too expensive to alter the furnace to fit the flame. The mistaken impression exists generally that a burner is ahout the only equipment necessaw-that it is hooked

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up:to a steam pipe and nothing else is required. However, in addition one must inst.al an oil storage tank of ample capacity, oil strainers, fuel oil pumps and governors, heaters, piping and fittings for both oil and steam, pressure gages, thermometers, steam traps, control valves, relief valves, and reducing valves. Strainers and pumps are generally installed in duplicate to insure continuous operation. STEAM-JET BURNERS-The method of the steam-jet burner is t o break up the oil into a fine vapor by the direct action of steam. Usually a thin, long, fan-shaped spray is produced and is forced to pass over the brick floor of the furnace while burning. The thinner the spray, the better. ‘The brick in the floor, called “checkerwork,” are laid with openings hetween so that sufficient air can enter to support combustion. There are two types of steam-jet burners-namely, the external atomizing type and the internal atomizing type. The advantages of the steam-jet over the mechanical type of burner are: less difficulty in producing a spray; temperature and pressure of oil may be lower; greater simplicity and less expense in its use; greater flexibility; and better draft with less power. On the other band there are some important objections to the steam-jet burner which should be considered before selecting that type. In the first place, the steam used cannot be recovered, resulting in a greater volume of gas-the volume of the steam being added to the volume of the air. Extra prorision must sometimes he made to take care of this additional volume. The steam will condense on cool surfaces and cause the adherence of soot, which may then cake in hard layers, removable with great difficulty, as on economizer surfaces and inside of the stack. Compounds such as sulfur, commonly present in fuel oil, are liable to unite with the steam and form acids. These acids (usually sulfuric acid) attack and corrode the boiler, steel stack, or other metallic surfaces. Sometimes oil contains as much as 4 per cent sulfur. Spalling is sometimes caused by the action of the steam upon the furnace wslls. Finally, the steam-jet type is more noisy than the mechanical type.

Vol. 17, No. 1

There is nothing new or experimental about the steam-jet burners, however. They have been used for many yearslonger than other types of burners-and they are now used under all kinds and capacities of boilers-water tube, horizantal return tubular, Scotch marine, and vertical types. Pressures used for forcing the oil through the burners vary all the way from 5 to 110 pounds per square inch, wlieress the atomizing pressures, whether with steam or air, vary from 2 to 110 pounds per square inch. The oil pressure should never exceed the atomizing pressure; in fact, the atomizing pressure should be a trifle greater than the oil pressure-about 5 pounds. Superheated steam gives better results for atomizing than saturated steam. Steam should always be perfectly dry or superheated; if wet it is liable to extinguish the fire. It is claimed by some manufacturers of oil burners that with the use of certain burners the consumption of steam runs as high as 7 per cent of the total steam produced by the boilers. This is a point worth watching. One manufacturer states that a burner should not use more than 1 per cent of the steam, while another manufacturer places the minimum a t 1.3 per cent and the maximum a t 10 per cent. An engineer who has made numerous tests on burners states that all burners tested atomized very well, and the fuel consumption of each operating under the same conditions was practically the same. Ife also found very little dBerence in the amount of atomizing agent used. Nearly every burner on the market has a different shape and combmation of openings, but judging from these tests they have no effect on the efficiency.

U Fro. &-A SraAar-Jsr BURNERW H ~ C PRODUCHS H A Colilcn~ FLAMB AND Warca O B ~ A I ITS N ~ A m POB SUPPOBTINO Corrausrrolr T H ~ ~ O U D H * SuaI O V ~ ~ I I “RHCISI~~R.’* WE THISS r s ~ a - JBsV ~ ~ N B HAS R TSB ADVANTICS 0 s TRB MBCBANICALType IN TEATIT CAN BB Pr.bcE0 IN Tisas A N D B ~ I CS%BCKBX-WuoRx c ~ IS UWNBEBSSARY

Air may be used in place of steam as the atomizing agent. To the average chemist it may seem on first thought that air should give better results because, even where steam is used, air is required for combustion. However, it has been found that atomization with steam gives better results than with air. Steam is surer, safer, and more satisfactory. To furnish air for atomizing requires the use of an air compressor,

January, 1925

INDUSTRIAL AND ENGINEERING CHEMISTRY

which usually costs much more than the first cost of the burners. Mechanical Burners Pure water is o€ten scarce, as on board ship, in which case it is desirable to save as much steam as possible. Under such conditions the mechanical type of oil burner is used.

FIQ.

6-A

MECHANICAL BURNER

In

are operating on oil pressures of less than 100 pounds per square inch." In general, the pressures range all the way frbm 30 to 200 pounds per square inch. One disadvantage of the mechanical burner is that if the stack is not high Forced draft is usually required unless the load is low. A combination of natural and forced draft is often used with the mechanical burner.

OF C O U R S E , AFTER O I L PARTICLES LEAVE THE SHOWLNQ I T S OPERATION. AIR THEYD o N O T CONTINUE T o FOLLOW SPIRAL P A T E S AS INDICATED

other words, air is used instead of steam. Again, for certain kinds of work air is preferable to steam, particularly where the amount of moisture in the furnace must be reduced t o the minimum, Most mechanical burners operate under similar principles. The oil is given a whirling motion a t the burner tip so that the oil spray enters the furnace in the form of a hollow cone, owing to centrifugal force. The oil mixes with air after leaving the burner tip. According to theory the mechanical burner should be more efficient than either the steam-jet or air-jet burner. In practice, however, the average mechanical burner has given more trouble. Moreover, some of them use as much steam for their operation as do those of the steam type. These disadvantages, however, are being rapidly overcome, and in some types of mechanical burners they are now almost entirely eliminated. There is an important advantage of the conical spray over the flat steam-jet spray in that its area is greater; consequently the furnace need not be so long. Also, the air supply passes through a register surrounding the burner and can be regulated more accurately than air through brick checkerwork. It is possible to arrange mechanical burners in tiers, although this is now practical with some steam-jet types. With the mechanical burner there is less furnace loss because of the absence of steam that is always lost up the stack with the steam-jet type. Mechanical burners are less noisy than the steam-jet type. High efficiencies and high boiler capacities are obtainable with the mechanical type. Sometimes the mechanical method is called the high pressure method. This is not a good name, however, because, as stated by one prominent manufacturer, "75 per cent of the mechanical oil-burning systems installed by this company

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FURNACE A N D ARE MOVING IN

MID-

I n oil refineries where there are gas compression plants, gas is commonly used for atomizing instead of steam or air. Combustible gas is ideal for this purpose, because the gas itself is a fuel and adds to the heat value of the oil. Common engineering practice with mechanical burners is 2 pounds of oil per hour per cubic foot of furnace volume. Proper Heating of Oil

As already mentioned, oil is usually preheated before it is fed into the furnace by either type of burner. This preheating is generally in proportion to its gravity. The heavier the oil the higher the temperature required. I n general, this approximate rule may be safely followed: Up to 20" B6. oil should be heated t o 15 or 20 degrees below flash point to insure free flowing. Oils over 20" Be. need only be heated sufficiently to insure their flow.

Claude C. Brown, in Power Plant Engineering of November 15, 1923, gives the following approximate temperatures to

,which oils of various gravity may be most advantageously heated : Gravity of oil

Minimum working tempzrature

Be. 24 to 30 20 to 24 17 to 20 15 to 17 14 to 16 11 to 13

80 to 100 100 to 140 140 to 160 180 to 180 200 to 220 240 to 276

F.

It is plain that if the gravity of the oil is not known this table is of little value, in which case the chemist may determine the best temperature by experiment. Even if the gravity is known, experimenting is advisable. Some oils give most satisfactory results when heated t o as high as 300" F.

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INDUSTRIAL AND ENGINEERING CHEMISTRY

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It will be obvious that unless the oil is hot enough the burner will smoke and combustion will be incomplete. If, on the other hand, the oil is heated too hot, the burner will lose in heating capacity because of the increased volume of the hotter oil passing through the burner. When the weight of oil passing through the burner per minute is reduced, less heat is produced in the furnace. The weight per minute is what

Vol. 17, No. 1

of oil pumps and two sets of strainers, so that in case one is out of order the other is ready t o operate. The engineer stated that he has never been forced to switch from one to the other, because he always keeps both in good operating condition. According to burner manufacturers it is considered safe practice in oil burning to allow from 2.5 to 3 cubic feet of

TANKS.

OF T H E MECHANISM REQUIRED IN MECHANICAL OIL-BURNINGSYSTEMS, N O T INCLUDINQ T H E THEOIL FIRSTP A S S E S THROUGH A STRAINER, A PUMP,A HEATER, A DISCHARGE STRAINER, THE BURNER,AND FINALLY INTO THE FURNACE

FIG. 7-MOST

counts. If increased in volume to too great an extent by undue heating, the heating capacity will drop. Oil must never be heated above its flash point before it reaches the burner. Preheating causes carbonization and clogging of the piping system and burners.

combustion volume per boiler horsepower. Thus, with a 100-horsepower boiler the combustion volume should be a t least 250 cubic feet.

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Information to Give Manufacturers

When writing manufacturers of burners for information or prices it is well to give them such details as: number of boilers; The engineer in a comparatively small plant, having make and type of boilers; boiler horsepower; number of two horizontal return tubular boilers each of 80 horsepower, hours' service per week; number of doors on each boiler; stated that his concern is saving $500 per month since in- depth and width of furnace; height from grate to tubes or sthlling oil-burning apparatus. He said that before the oil shell; condition of settings and furnace, whether good, fair, burners were installed he did all the firing himself; conse- or poor; water-tube or fire-tube boilers; live steam pressure quently, there has been no saving in labor. Nevertheless, and exhaust steam pressure (available) ; oil storage capacity; there has been a remarkable saving in money. Steam is will boilers be forced to operate above capacity; will they now generated in the morning in about five minutes during operate a t capacity or below capacity; how often can oil be the week days. A mechanical blower is first used to gen- obtained; can oil be stored above ground or must it be stored erate the steam. After sufficient steam pressure is developed under ground; preference for steel or concrete storage tanks. the boilers are brought into action for firing themselves and Make a rough sketch giving the principal distances and the mechanical burner is swung out of the way. Once. showing the layout of the boiler room and surrounding space, started, the operation of the boilers and of the entire plant so that the manufacturer will know where pumps, tanks, etc., becomes a comparatively simple matter. By means of the may be placed. State whether or not one boiler must be heaters the oil is kept a t 180" F. Burners of an old type are constantly on the line and what pressure must be held; used, but they are given very good care and do not give any whether electricity is available; alternating or direct current; trouble. They are cleaned every other day. The boilers what voltage, how many cycles, how many phases; is steam are provided with two sets of burners. One set is used one or mechanical atomizing preferable; number of tons (2000 day while the second set is being cleaned during the same day. pounds) of coal burned per month; cost of coal per ton deThe clean set is then used the next day and the first set is livered to boiler room floor; kind of coal burned; heat value cleaned, etc. The engineer stated that he has never had in B. t. u. per pound; cost of labor per month for firing and trouble with clogging, He is not compelled to change the handling ashes. burners every day but does so for the sake of absolute certainty. The boilers operate with excellent uniformity of The Bureau of Standards has constructed apparatus and pressure. The needles point at exactly 100 pounds pracplans for the study of the surface changes produced on tically all the time. Occasionally, the pressure drops 2 outlined metals by ultra-violet light acting in various gases, which it is or 3 pounds, but the automatic device immediately brings hoped will give data of interest on surface films and the mechanit back to 100 again. In the boiler room there are two sets ism of corrosion. Experience in One Plant