LIQUID FUELS

Evening Post, Volume CV, Issue 123, 26 May 1928, Page 9

LIQUID FUELS

HOW THEY ARE BEING -PRODUCED The, heating of geologically recent coals under tho exclusion of air deems to have been hitherto the simplest method for the production of liquid fuels from solid fuels, but a new method has now been adopted by which even greater results are obtained by great pressures. Destructive distillation by either method yields a tar in addition to certain gases and a residual coke, which contains constitutents of a petroleum character. Gas coals of recent geological periods, that is, ordinary coal, yield.up to 12 per cent, of this tar, while certain lignites, of which brown coal is one variety, and oil shales aro likewise suitablo materials for the manufacture of tar and petroleum by various methods of distillation. The Scottish shale-oil industry and the brown coal carbonisation works of central Germany operate along those lines. In the Bcrgius process for the lique: faction of coal, which, is, one method adopted in Germany, hydrogen is made to react .wifjh coal,, at a pressure of more than 100. atmospheres and at a tomperature of about 450 degrees. Under this process the coal is ground and kneaded with 30 per cent, of tar into a paste, which is continuously pressed into the high-pressure autoclave. It is understood that'the coal is thus first carbonised, the temperature being sufficiently high for such a. purpose. Reaction in a given direction has quite' recently been established by experiments in which the carbonisation was obtained under ordinary pressure, but the hydrogeneration, or liquefaction, has only been obtained under exceedingly high pressure. For the process all coals arc not suitablo, only those rich in volatile constitutents reacting to tho process. The oil of tho Bcrgius process is said not to bo equal to natural oil, but it contains an ample proportion of gasolene, though the whole product is more closoly related to primary tars thau to petroleum. '. The process is exceedingly expensive owing to. the extreme cost of the liighpressure apparatus required, but this is a side to tho discovery which will probably be overcome as timo passes and tho utility of tho process is proved to be of value to'industry. There aro several other methods by which similar results may bo obtained, some from liquid fuels and others from hard fuels, while gaseous fuels frequently contain vapours of liquid fuels at low-boiling points. There aro benzine vapours in coke-oven gas, and lowtemperature carbonisation retorts always contain vapours of this character. Ihose vapours may be condensed by cooling or by compression, or by a combination of the two methods, both of which yield a liquid directly. Many attemptshave been made sineo 1910 to effect the low pressure carbonisation of bituminous coal commercially, especially in Germany, where tho subject has been considered one of primary importance ,in view of tho advancement of the v internal' combustion engine and tho. npod for fuel therefor. Hitherto the process has not met with a great deal of success, and the results have boen more or less of a negative nature but the cablegram indicates that a distinct movo forward'has been made, and that the petrol .from this source will bo possible in the near future, a very valuablo discovery for those.countries which possess'•coalfields' but do not havo any say in tho distribution of the world's oil supplios.