LOW TEMPERATURE CARBONIZATION.
ITo THE EDITOR or THE " SPECTATOR."] SIR,—The above subject has recently assumed some prominence in your columns. I doubt, however, if the advocates of the process realize that the amount of coal consumed on the open hearth represents but a portion of that used for all purposes. And those familiar with the process cannot but agree that its commercial history has been far from fortunate, and that this lack of success is undoubtedly in part due to its inherent defects. For instance, an unbiased expert states that the chief product of the process, semi-coke, burns more easily in the domestic grate than ordinary coke and without the smoke of bituminous coal, while the process produces quite as much liquid tar as the ordinary gasworks method. Other products are gas and ammonia. Of the demerits of the process, the friable nature of the product, semi-coke, is not the least. And this semi-coke may consequently very easily crumble in transit, and crumbled coke is not regarded by users with favourable eyes. Indeed, it is one of the bêtes noires of the gas manager. Moreover, although the gas obtained by the process is rich in quality it is lacking in quantity; in fact, it amounts to only about half of that obtained in ordinary gasworks, and about one quarter by the more advanced methods. And it should be remembered that the thermal and monetary costs of carboniza- tion have to be incurred whether coke or semi-coke is manu- factured. These costs have to be borne by the products, and it is hard to realize how the extra financial burden can be borne by the semi-coke. Consequently, a grave problem is presented by the sacrifice of gas for semi-coke.
It should be pointed out, too, that ammonia is more the product of medium temperature carbonization than of low temperature, and, although the latter process will produce tar oils in quantity, it will not necessarily produce them in greater quantity than in such a gaswork's apparatus as the continuous vertical retort. To sum up, it seems that, even if low temperature carbonization with the general use of its chief product of eemi-ooke in lieu of coal becomes a success, it will exact reparation in the shape of a price considerably increased. This would have to be debited against the credit side of the account of freedom front fogs and those other penalties exacted by the use of raw coal for fuel. The colliery owners of this country are undoubtedly keenly alive to the potentialities of the process. Indeed, they have as a body for years past given the subject of low temperature carbonization unremitting attention, and they have expended a small fortune in experiment and research, although the War, com- bined with the great industrial disputes which have arisen since the Armistice, have not unnaturally hindered develop- ments. Unfortunately, too, the financial situation of the coal- mining industry is now in such a state of jeopardy that little money can be available for experiments on a. grandiose scale. It should further be recollected that it was chiefly through the instrumentality of the coalowners that Sir John Cadman was able to conduct his valuable research work at the laboratory of the Birmingham University. Sir George Beilby, F.R.S., Director of Fuel Research, and one of the greatest living authorities on the subject, in June last at the James Forrest Lecture delivered by him at the Institution of Civil Engineers, was at considerable pains to point out that the chief difficulty yet to be surmounted was the evolution of an efficient and inexpensive apparatus to realize on an economic basis the products of low temperature carbonization. These are his ipsissima verba:—
" Until a fair-sized industrial plant has been carried on con- tinuously for a long period, making and disposing of all the products of carbonization under steady market conditions, no one can say whether or not the business will be a profitable one."
And he added that the treatment of even a small proportion of the annual output of coal would involve an enormous capital expenditure. The installation of carbonizing plant for 35 million tons would, he estimated, cost between 30 and 40 million pounds sterling.
In face of this considered opinion. one is almost forced to conclude that the question whether the industry can at present engage in so great a scheme scarcely arises. As I have indicated, organized opinion among colliery owners is strongly biased towards the scientific utilization of fuel. They con- sider, however, that the subject is at present but slightly advanced from the experimental stage. With an ardour and zeal which is easily understandable, inventors of carbonization processes have made claims for their scientific progeny which seem rather extravagant to those who are not their indulgent sires. These processes have been subjected to careful scrutiny in the hope that from the economic standpoint they might prove to be practicable. And personally I have not the slightest doubt that directly it is unquestionably demonstrated that plant can be erected and operated on a commercial basis, no eloquence will have to be used to persuade coalowners to support a process of low temperature carbonization.—I 'am,
Sir, &c., PAUL. COVENTRY.
King Street, Covent Garden, W.C. 2.
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