OIL FROM COAL

Taranaki Daily News, 9 July 1930, Page 7

OIL FROM COAL

THREE PROCESSES. NEW ZEALAND RESEARCH. At a meeting of the chemical section of the Wellington Philosophical Society held recently, Mr. W. A. Joiner, of th Fuel Section, Dominion Laboratory, gave a paper entitled “Oil from Coal.’ The speaker dealt with the three chief ways for the extraction of oil from coal: (1) Low-temperature carbonisation; (2) the Bergins process of treatment with hydrogen under great pressure aij,d at ah elevated temperature; and (3) the synthetic process, whereby gases produced from coal or. coke can be transformed into liquid products. This is often known as the Fischer process, after Dr. Fischer, who carried out pioneer work in this field in Germany. By distilling or carbonising coal at low temperatures, at or below 600 degrees C., the following products are obtained: Carbonised residue, or smokeless fuel; tar-oil, and gas. The tar-oil yield is at a maximum when carbonisation is effected at from 500-550 deg. C., but it also depends considerably on the design of the carbonising plant. . An investigation on the low temperature carbonisation of New Zealand coals is being carried out at the Dominion Laboratory for the Fuel Research Committee of* the Council of Scientific and Industrial Research. Various New Zealand coals are being treated, and work has been completed on coals from the Waikato and Southland districts. These coals are similar in type, and are noncoking, so that in most cases the carbonised residue would require to be briquetted. They give the following approximate yields of products per ton of coal carbonised: Carbonised residue, 10 to 11 cwt.; tar-oil, 15-17 gallons; gas, about 4000 cubic feet.

In considering the development of the procesflea described it was pointed out that coal oil cannot compete successfully with petroleum products at present. All oik from coal, by whatever process they are obtained, are crude products and must bear the cost of refining in the same, way as petroleum crudes, to which must be added the extra cost of mining, and processing the coal as compared with that of obtaining the oil by boring. Practically the only use for' low-temperature taroil at present is that of a fuel oil, with perhaps the exception of the lighter fractions and the pitch. On the other hand, if low temperature carbonisation is to be undertaken with a view to enhancing the value of or creating a market for low-grade or slack coal, there will always be a certahi amount of tar-oil. produced,, amb it is

highly necessary that this product should be.further investigated with a view to its best utilisation if the carbonisation projects are to yield the maximum return. In regard to’ the Bergins process, it was pointed out that a considerable amount of investigation has been done by the University of Birmingham and the Fuel Research Station at Greenwich. The yield of oil obtained by this process is in the neighbourhood of 60 per .cent, by weight of the raw coal treated, or over 100 gallons per ton. In his original experiments, Dr. Bergins, of Germany, made use of an experimental apparatus, with a capacity of about three-quarters of a ton per day. Owing to the high pressure and temperatures employed a great many engineering difficulties had to be overcome before 1. full-sized commercial plant could be erected. It was stated that a plant has been constructed in Germany capable of treating 18,000 tons of coal per annum, but so far no news of its performance has been received, The Bergins process has been applied to the treatment of low temperature tar oil, and also petroleum residuals, in order to increase the yield of petrol. It is believed that the I. G. Farbenindus- ■ trie in Germany is producing considerable quantities of gasoline from low temperature tar by this method. This is made possible owing to the very low cost of mining certain varieties of German coal.

The formation of synthetic oils by the Fischer process depends on the interaction of hydrogen and carbon monoxide in the presence of a catalyst. Originally high pressures were used, and a product termed “Synthol” was obtained. “Synthol” consists of a mixture of complex alcohols and other compounds, and although it has been used successfully as a motor fuel, it possesses certain serious disadvantages for this purpose. By working at atmospheric pressure hydrocarbon oils have been produced by the use of suitable catalysts. By means of a similar process large quantities of methyl alcohol are now produced commercially. Methyl alcohol, however, is not suitable as a motor fuel.