CARBON FOR GAS MASKS

Press, Volume LXXIII, Issue 21991, 15 January 1937, Page 6

CARBON FOR GAS MASKS

PRODUCTION FROM COAL EXPERIMENTS OF BRITISH RESEARCH BOARD «f'?.f)M 01'?. OWM CORBESPO.VDENT.) LONDON, December 17. Cheaper carbon for gas masks and the conversion of tar into motor spirit and fuel oils are two interesting sections of the work of the Fuel Research Board, whose annual report has just been issued. At the request of the War Office the board has produced from British coal an active carbon for use in gas masks. This is considerably cheaper and nearly as good as the best obtainable from other sources, and would perform a valuable service in war time by absorbing noxious fumes and vapours. "It was known."' says the report, "that a suitable blend of coals, when pulverised and briquetted under high pressure, in the absence of a binder, would give, after carbonisation and subsequent activation with steam, a high-grade carbon. It was desired to ascertain whether suitable carbon could be produced without briquetting, as this would simplify the process. The knowledge which the Fuel Research Station possessed of the behaviour of different types of coal on carbonisation suggested that the type of coal most suitable for the purpose was one which was low in caking power but which possessed just sufficient caking . power to form a hard coherent coke when carbonised in lump form. A suitable coal would be one which, though possessing this property, did not pass through a plastic stage during coke formation. A Theory Confirmed "Coals of this type arc the durain coals, rich in plant remains, which occur in bands in many of the scams of bituminous coals in Great Britain. The caking power of these durain bands varies over fairly wide limits. and it was apparent that the first choice of coal should fall upon those which were known to have exactly the desired behaviour on carbonisation. To prove this assumption, small quantities of several coals were carbonised at the Fuel Rcserach Station, and the coke was activated with steam in a laboratory The results of these experiments confirmed the original ideas as to the type of coal required." tho report continues. Dealing with the. conversion of tar into motor snirit and fuel oils, the report says: "The semi-commercial scale plant ei-ected by the Fuel Research Station designr-d tor the treatment of 200 to 400 gallons of raw material a day has worked satisfactorily during the year. This plant was erected for two objects. The first of these was to work out a technique and method of operation applicable to a large-scale plant. The second entailed the examination of the effect of variables such as temperature and pressure to correlate the results obtained with those from small-scale laboratory plants, and ultimately to determine the best working conditions for various raw materials. The first objective has now been accomplished. "The engineering difficulties and those of temperature control have been overcome and experience has been gained which would enable a simple large-scale plant to be designed if required. Work is now in progress on the second objective, but before optimum conditions can be established the c.rcat difficulty associated with the rapid deterioration of the catalyst, that is, the material added to make the conversion of tar to oil nroceed rapidly, must br; overcome. The molybdenum sulphide now used as a catalyst has a life of four to six weeks, and this is insufficient for large-scale practice. "The experiments on the production of a first-class lubricating oil from coal have been continued, but have so far been unsuccessful. It now appears," •he report says, "that the most hopeful line of attack is the use of oils obtained by synthesis from carbon monoxide and hydrogen. A plant is being erected to produce sufficient of this raw material for further experiments. Work on the conversion of coal into oil by hydrogenation has, for the main part, been limited to testa on the suitability of various coals, including coals from the depressed areas, for the process." Mining Developments The report also refers to the striking' developments in the mining of coal and in its preparation for market. In the last seven year.s the amount of coal cut by machines has increased from 23 per cent, to more than 45 per cent, of the total output. The amount of coal in small -sizes cleaned by washing or dry-cleaning processes has risen in the same period from 20 to 40 per cent. It is stated that these developments have been accompanied by an increased efficiency in the use of coal. As a result, there have been remarkable reductions in the last few years in coal consumption, whereas the total energy obtained from coal and usefully applied has actually increased. Small coal, graded and cleaned to meet the needs of modern industrial practice and the capacity of the modern cellar, now commands prices as good as, or better than, those obtained in the past for large coal.