So much has been written of late as to the use of petroleum as fuel for the purposes of steam-raising, that the reader is bound to be more or less au fait with the subject. It is, of course, one of vast importance, and during the next decade is certain to receive far more consideration than it has hitherto done, owing to the general desire that our coal wealth shall be conserved as much as possible. Given the one allowance that oil fuel can be procured at anything approaching a reasonable figure—and there is no reason why, in normal times, this reasonable price should not be prevalent all over the world—then petroleum offers many advantages over its older competitor, coal. The ease with which large quantities can be handled, the simple method of operating anything which is fired by petroleum as fuel, and the fact that its heat-giving units are far higher than those of coal, will ever be the chief factors governing its popularity.

Many years ago, fuel oil made its serious dÉbut, but at that time the supply of the product was very uncertain, and, consequently, progress in passing from the old to the new form of power-raising was slow. To-day, however, matters have materially changed. The crude oil output has been immeasurably increased, and many fields whose production of crude oil is essentially suited for fuel purposes have been opened up. In this respect, the oil-fields of Mexico have no parallel, and it is recorded that, once these fields are provided with adequate storage and transport facilities, they can easily supply the whole of the fuel oil necessary for the world, and at the same time have immense quantities to spare.

But, though the subject of petroleum as fuel has aroused much attention for some years, there is still an erroneous idea prevailing as to what really is fuel oil. A word or two on this question will, therefore, not be without interest. Fuel oil is that portion of crude oil which is incapable of giving off by the process of ordinary distillation those lighter products of petroleum known as motor spirit, illuminating oils, or lubricants. It is, in a word, the residue of distillation which is unsuitable for refining purposes. It represents a black, tarry liquid, and is, of course, minus those fractions that go to produce the refined products. Many there are who refer to crude oil as fuel oil, but this is a misnomer, though crude oil, in many instances, is utilized for the purposes of fuel. In this chapter, however, when I speak of fuel oil, I am referring not to the crude oil as it comes from the ground (and which has a comparatively low flash) but to the article of commerce, the residue of distillation, which is the real article—fuel oil.

The headway which fuel oil has made during the past few years has been remarkable, though it is safe to say that its general use is still in its infancy. In no matter what capacity it has been tried as a heating or steam-raising agent, it has proved itself capable of withstanding most successfully the most stringent tests, and has convinced all who have given the question serious consideration that it holds numerous advantages over coal, yet has no drawbacks. Perhaps the most recent impetus which has been given to the use of fuel oil is that following the introduction of it, and now its general adoption, throughout the units composing the British Navy. On land, however, it has for some years achieved marked distinction. Especially is this the case in regard to its use on locomotives, the United States railways alone consuming last year over 6,000,000 tons of fuel oil. In the realms of industry, fuel oil, too, is claiming the attention of those large industrial establishments, and to-day is largely used for creating intense heats, such as are necessary in hardening, annealing, melting and smelting, rivet heating, glass-melting, etc.

Let me first of all refer to the use of oil fuel for marine purposes. Fifteen years ago, its use was very strongly advocated by Sir Marcus Samuel, Bart., for marine purposes, and he approached the British Government in an endeavour to get it taken up. Matters moved very slowly, but eventually oil fuel was adopted, and Admiral Sir William Pakenham asserts that it was due to the unceasing efforts of Sir Marcus Samuel that the Admiralty vessels constructed during the war were oil burners. The largest of this new class of vessels is the Queen Elizabeth. Oil fuel is now largely used in place of coal on our great liners, vessels like the Aquatania and Olympic having gone over to its general use.

There are, of course, many reasons which have commended fuel oil to the experts as a substitute for coal. In the first place, inasmuch as one ton of fuel oil is equal to more than one-and-a-half tons of coal, the radius of action of units fitted for utilizing fuel oil is increased over 50 per cent.—I speak from the point of view of bunker weight. Again, one ton of oil occupies considerably less space than an equivalent weight of coal, while this advantage can be materially increased—as is now the usual practice—by carrying the fuel oil in double-bottom tanks. Then the bunkering question is one of vital moment. Fuel oil can be taken on board under far cleaner conditions, and at a greatly accelerated rate, than would be possible with coal. There is no arduous manual labour required. Once the hose connections have been made, the fuel oil is pumped on board at the rate of hundreds of tons an hour, and a few hours suffice to re-fuel our largest battleship. But it is when bunkering at sea is required that fuel oil further emphasizes its immense advantages. This question was some years ago one of the problems of naval strategy: to-day it is regularly carried out in the simplest possible fashion, hose connections to a standing-by oil tanker being all that is required.

Another advantage of fuel oil is that materially increased speed can rapidly be attained, for, with fuel oil fired furnaces, the ship’s boilers can be forced to nearly 50 per cent. above normal rating without that great strain on the personnel which would be essential in burning coal under forced draught. Then there is the great saving of labour effected when burning fuel oil, the stokehold staffs being reduced by quite 90 per cent. The fuel oil is automatically fed to the furnaces and mechanically fired, the maximum heat of the oil burners being attained within a few minutes of starting. But the absence of smoke when the battleship is proceeding at full speed is, perhaps, one of the most important advantages which the use of fuel oil gives to the units of the fleets employing it. The emission of dense volumes of smoke, which are ever present on a coal-fired vessel, is quite absent when fuel oil is used, and this advantage is twofold, for not only does it prevent the giving away of the location of the battleship, but it also renders its own gun-fire more efficient.

The advantages attendant upon the use of fuel oil for naval vessels are, in the main, also strikingly apparent when oil is adopted for the mercantile marine. It is many years ago since the oil tankers of the “Shell” Transport and Trading Company, Ltd., commenced to do the voyage regularly from the Far East to this country and back without an intermediate port of call. To-day, practically every oil tanker afloat burns fuel oil. But, of recent date, fuel oil has reached wider application by reason of its being adopted on many cargo and passenger vessels, and, had the European War not considerably hampered ordinary shipbuilding construction, we should have seen ere this a number of the largest vessels crossing the Atlantic exclusively running on oil. In fact, arrangements have been made whereby many of our Transatlantic lines will operate exclusively on fuel oil, which will be taken on board in the United States.

My friend, Mr. J. J. Kermode, of Liverpool—the well-known fuel oil expert—has taken the most prominent part in calling general attention to the immense superiority of fuel oil over coal, and it is due to this gentleman’s untiring energies that not only does our Navy to-day use fuel oil to such an extent, but that those responsible for ocean passenger transport have taken the matter up so seriously. There are three general headings under which fuel oil use will affect transport costs. They are as follow: (a) by increased passenger or cargo capacity, (b) by increased speed, and (c) by a great reduction in running costs. As to the increased capacity, I have already shown that fuel oil can be stored in considerably less space than coal, and the simplicity of both bunkering fuel oil, and using it on vessels, has also been touched upon. With reference to the increased speed which vessels utilizing fuel oil can attain over those running on coal, I have a concrete example in front of me. Two sister ships of the Eagle Oil Transport Company—the San Dunstano and the San Eduardo—each of 9,000 tons deadweight capacity, are fitted to burn coal and fuel oil respectively. Upon a trip carried out under careful observation, the weight of fuel consumed worked out as two to three in favour of fuel oil, while the indicated horse-power developed showed an 18 per cent. improvement in the case of the oil-fired vessel. But the striking fact of the comparison is that the San Eduardo made the round voyage to Mexico—out and home—eight days quicker than the other, this additional speed being solely due to the fact that with fuel oil it was possible to maintain consistent speed throughout the voyage—an impossible matter when coal is consumed. If space permitted, I could enumerate many cases where the results in favour of fuel oil are even more strikingly apparent, but I will content myself by briefly referring to calculations made by Mr. Kermode, based upon voyages of our largest liners: they are sufficiently interesting and suggestive to record here. On an average, says Mr. Kermode, to maintain a speed of 25 knots, 5,500 tons of coal are consumed upon the voyage between Liverpool and New York by one of the mammoth liners; or 11,000 tons for the round trip. Some 3,300 tons of fuel oil—which could be stored if necessary (and as will frequently be done in the future) in the double bottom of the vessel—would, by automatic stoking, do even more work than 5,500 tons of coal. Calculating the daily consumption of 600 tons of coal now used for 24 hours, this represents about 2,000 tons less fuel on a five days’ trip, land to land run, or 4,000 tons less, out and home. The utilizing of the vacant space thus saved for merchandise would bring in a very handsome income. Of the 312 firemen and trimmers now employed for a coal-fired liner, 285 might be dispensed with, and occupation found for them under healthier conditions ashore, say in handling the additional cargo which would be carried. The saved accommodation in this respect could be allotted to third-class passengers, of whom at least another 250 could be carried. Our mammoth liners are fitted with 192 furnaces in order to produce 68,000 horse-power (as was the case of the Mauretania and the Lusitania), and, on the assumption that thirty-two fires are cleaned every watch, 10,000 indicated horse-power is lost every four hours through burning down and cleaning, a quite unnecessary operation with fuel oil. Figures such as these show the startling possibilities of fuel oil for marine purposes.

But it is on land, as well as on sea, that we find fuel oil rapidly making headway, for, as far back as 1889, hundreds of the Russian locomotives went over to the burning of a petroleum residue. This was the first practical application of fuel oil for railway haulage. To-day, nearly 50,000,000 barrels of fuel oil are consumed annually by the various railroads in the United States, and, according to the official figures I have of the total mileage of fuel oil for the past twelve months, the United States oil-burning locomotives did journeys aggregating over 145,000,000 miles. Mr. Hall, of the American International Railway Fuel Association, is responsible for the statement that, owing to the fact that the steaming capacity of the engines is materially increased, a locomotive running on fuel oil can haul a load of considerably greater tonnage and at a much increased speed than would be possible with a coal-fired engine. Many Continental railways use fuel oil rather than coal; the Roumanian and Austrian State Railways, the Western Railway of France, the Paris and Orleans Railway, being a few of the principal.

So far as England is concerned, the use of fuel oil has not made great headway, for the reason that, while on the one hand, the majority of our great railway systems pass through the coal-producing fields, there has, on the other hand, until recently been an absence of organization for the supply of fuel oil. The Great Eastern Railway many years ago successfully ran oil-fired locomotives.

It is evident that oil fuel will be increasingly used in the future for locomotive purposes, and at the time of writing—December, 1919—the L. and N.W. Railway are carrying out experiments on express engines, with a view to being able to some extent to discard coal.

In our industrial life of to-day there are a vast number of instances where fuel oil is rapidly displacing coal: the oil-fired furnace has been brought to a stage of perfection, and is being extensively and increasingly employed both in this country and abroad in regard to metallurgical and industrial processes. Without going into detail respecting the numerous spheres in which the new fuel finds profitable employment it is safe to say that these are being extended every year.

A wealth of inventive effort has been bestowed in the perfection of the burners employed to consume fuel oil. Leaving aside for the moment the principles governing the use of oil in the internal combustion engines of the Diesel or semi-Diesel type, fuel oil used for the production of power is introduced into the furnace in the form of a spray, this being accomplished by atomizing the oil in its passage through a specially designed burner. Of these burners, there are numerous makes upon the market, each of which possesses its own characteristics and advantages. The one feature common to all fuel oil burners is the arrangement for atomizing the oil fuel into a fine spray, so that each particle of fuel shall receive sufficient oxygen to ensure its complete combustion. Theoretically, it requires about 14 lb. of air to effect the combustion of 1 lb. of oil, and on the thorough combustion of the fuel oil depends the efficiency of the furnace. There are three distinct methods by which the atomization is brought about, and each of these means possesses its advantages and limitations. By one method, the fuel oil is atomized by the use of steam; by the second method, compressed air is used; while a third system—that of applying pressure to the oil supply itself—is sometimes adopted. Steam is the method usually employed for stationary boilers and locomotives, for it is the simplest to manipulate, and does not call for the employment of auxiliary apparatus in the shape of air compressors or oil pumps, but most industrial oil furnaces work on compressed air, which gives exceptionally good results. There is no doubt that, with the use of compressed air, say admitted at a pressure of 80 lb., a saving in fuel oil is shown over using steam at similar pressure, but the cost of the compressing plant, which must be taken into consideration, is sufficient to wipe out the greater part of this advantage.

With respect to the use of the fuel oil direct under pressure, this system generally involves the heating of the fuel oil, as well as its filtration, the fuel being supplied under pressure by means of pumps. The system is extensively employed at the present time on marine boilers operating with forced or induced draught, and, in this connection, the Wallsend system stands pre-eminent.

Since writing the first edition of this little volume considerable advance has been made in connection with the use of oil fuel for general power-raising purposes, and much of this expansion has been consequent upon the introduction of a new burner—the “Scarab”—which is here illustrated. It is the invention of Lieut.-Col. Macdonald, and is the outcome of the war. When the Lieut.-Colonel was on service in Mesopotamia, he recognized the possibilities of oil fuel, for while wood and coal were being transported from India at great cost, oil was running to waste on the neighbouring fields of the Anglo Persian Oil Company. The Lieut.-Colonel therefore introduced a method of cooking by oil fuel, and immediately on his return to England he carried out experiments which led to the introduction of the “Scarab” burner. It is a simple contrivance, and is practically fool-proof, since there are really no parts to get out of order. The oil fuel flows through a tube by gravity, while another tube carries air compressed to about 10 lbs. pressure. The oil and air meet some inches distant from the mouth of the burner, and the combustion of the fuel, which is turned into a finely atomised spray, is complete. Experiments have been made with the burner for domestic purposes, and it has been adopted already in several London hotels for cooking purposes, though its general application is practically unlimited.