DEMAND FOR COAL

Evening Post, Volume CXIV, Issue 38, 13 August 1932, Page 26

DEMAND FOR COAL

SCIENCE ONLY HOPE

COLLOIDAL FUEL TRIAL

In 1913 Great Britain exported 73,400,000 tons of coal, in addition to supplying over 21,000,000 to foreign ships to replenish their bunkers. Last year tho exports had slumped to 42,750,000 tons and the bunker coal to 14,610,000 ton's. The above figures are given by a correspondent to . ''The Shipping World" in discussing the possibilities of colloidal fuel made from coal and oil as-was used on the Cunard liner Seythia recently for experimental purposes. The writer goes on to say that a large percentage of the coal exported abroad finds its way into the bunkers of British and foreign ships, so that it is no exaggeration to estimate that tho use of fuel oil afloat has robbed the British coal industry of the sale of between - 20,000,000 and 25,000,000 toils annually. Further, the oil fuel is almost entirely a foreign product, and its purchase by British shipowners adversely affects the trade balance of the country. No blame is attachable to the British shipowner, as, to maintain his position .in one of the world's most highly competitive industries, he must use the most economical fuel. The trouble really is that it has never been properly recognised that, as Mr. Walter Eunciinan put it in the House of Commons, "the hope of the coal-trade lies not in the arena of politics, but in that of science." ADVANTAGES OF OEn. It has been, proved conclusively by scientists and engineers that to burn coal in "the good old way" is a gross I misuse of a valuable raw material, for

that is what coal.actually is. Coal in, the lump-burns, it is true, but its coin-! bustion is a wasteful process. Again, in this form,' it as iiot easy to handle | in and out' of ships or frOm the bunkers to the boilers. Its storage takes up valuablo space and in the case of passenger liners, it leads to dirt and discomfort. Once it had been shown that oil fuel could be safely carried; at sea and used under boilers, there was no ] case to bo made for the use of coal on i such ships as liners and men-of-war. In any caso oil having established- itself as the most suitable and'convenient fuel for these types of ships, it would be impossible to convert those which were originally . built as oil"burners back into coal burners without going to very heavy expense. In the caso of some of them, warships especially, the conversion could not be carried out at all. ' . The case for oil was, and is, really based on two main considerations. In the first place, it is an economic fuel because practically the whole of its heat content can be extracted without loss or waste during the process of combustion, whether in the cylinder of a Diesel engine or in the furnaco of a boiler. Also, it can be easily handled and stowed aboard ship. To compete with oil effectively, coal must have these two attributes, and since it was at long last recognised to be essentially a raw material, the problem was to work it lip into a finished product with a basic, .nature.similar, to.that of oil. EXPERIMENTS WITH COAL. Since coal was known to contain oil, scientists—in- a number of cases successfully—endeavoured to extract the oil, but ..the trouble seems to bo that the processes of Nature are cheaper, and it is doubtful whether oil derived from coal will.ever be able to compote successfully with natural oil. Another line of attack was to grind the coal to a fine dust so that when forced by air through a burner each particle of coal would be completely surrounded by air, thus ensuring more perfect combustion. The New Zealand Shipping Company's liner Hbrorata was one of the first vessels to experiment with pulverised fuel. Pulverised coalfiring of boilers is more common ashore, both in Britain and in the : United States, than is generally known, but so far as its adoption for marine work is concerned, experiments have revealed difficulties which may not be very easy to overcome. Although in pulverised form, coal more nearly approaches oil than in its raw state, both as regards handling and the method by which its combustion is arranged for in the furnace, it still remains a substance and has not been converted into a fluid. ADVENT OF COLLOIDAL FUEL. The ingredients which confer varions properties on different paints are also substances, and as such could not be applied to other substances except through the medium of a vehicle which will not only hold their particles together, but will attach them to the surfaces to Which they aro to be applied. The substances are therefore ground down into oil or spirit vehicles. They are, in fact, mixed with the oil or spirit by which they are held in suspension. An official statement issued by the Cunard Company after the arrival back at Liverpool of the Scythia, shows that the main question at issue has been satisfactorily answered (writes "The Post's" London correspondent). This was, whether the mixture of crudo oil and extremely fine powdered coal would prove sufficiently stable under conditions at sea, remaining liquid and homogeneous so as to pass freely from the tank to the burners and there be as effectively atomised "as oil alone. It has done this. There has been no sedimentation of the coal! from the viscid mixture; the fuel has been continuously fed to the minute orifices of the burners without choking these in any way; the combustion is reported to have been perfect, and in confirmation of this claim it is pointed out that the smoke stacks of the • Scjthia have thrown down on

to the docks no perceptible ash or dust attributable to the oil-coal fuel. POSSIBLE ECONOMIES. The manufacture of the mixture if attempted on a scale commensurate with the requirements of ocean liners would bo a business requiring special plant not yet in existence. Many considerations would arise. Theoretically, use of the oil-coal would effect a large saving, for the Adam mixture is crude oil 60 per cent., and pulverised coal 40 per cent, by weight, and the coal constituent of the mixture is, at present prices, only one-fifth as costly as the oil. If the proportion of coal could ho increased the fuel cost would be still lower. The expense of bringing tho coal to the oil depots and pulverising and mixing it there would be an offset. It is not yet disclosed whether or not the Cunard Company will move in the direction of setting up mixing plants for their own use. EVERYTHING AS EXPECTED. Mr. A. W. Perrins, the Cunard Company's combustion engineer, who mado the round trip in the liner, said in an interview:— "Wo used the same heater and burner pipes as for ordinary fuel oil, with the exception, that a slightly modified diaphragm was fitted. The tanks were the same as for ordinary fuel oil, and the new fuel was easily pumped. The average consumption of the oil and coal was 17 tons a day for the four furnaces. The tank was quite clean after the fuel had all been used out of it. There was no deposit whatever, and the heater and strainers were also clear. I- am satisfied, after a thorough test that the new fuel is perfectly stable, and that it will remain stable' for all purposes in large quantities for three mouths at least. A fuel that remained stable for only three weeks would meet the requirements of a ' Cunard liner, but Vessels making longer oyages would require such a fuel to remain stable for three months at least. " \ "Everything turned out as I ex- | pected. There was no ash deposit on

the-boat-deck and tho only ash extracted . was from the smokeboxes, a normal thing in pulverised coal burning. There was no slagging iv the furnace. That also is •an • important point. We had to clean tho burners only twice as. of tor as when oil alone is used."