ENGINEERING.

Taranaki Herald, Volume LXVI, Issue 16038, 24 January 1918, Page 4

ENGINEERING.

(Melbourne Argus.) After hanging fire for many years, the use of pulverised' coal as a fuel for locomotives is extending rapidly in the United States, and as a large measure of success has already been attained it is not likely that it null be long confined to that country.. Indeed, it is said, though not officially, that the railways department of Now South Wales are about to make important experiments with pulverised ooal-burning on their locomotives. ' With coal burned in the ordinary way in a locomotive fire-box heavy losses are unavoidable. There are the standby losses, for example, which in some cases amount to 30 per cent.' Then where raw coal is hand fired the cleaning of the grates and fire-boxes at the ashpits is responsible for much delay. Moreover, with a. thick bed of fire it is impossible, except within very wide limits, to control the rate of combustion so as to make it commensurate with the work that is being done by, the engine. Another considerable source of loss, oven with the most .skilful firing, may be traced to the , constant opening of tho fire door, for this admits an excess of oxygen, and the temperature of the gases is thereby reduced. But if the coal is pulverised then these troubles are either eliminated altogether. or, if not, they are reduced to a minimum. As regards stand-by losses, for instance, these are wiped out once steam is up, for when the throttle is closed the supply of fuel can be cut off just ns it would he if the engine were oil fired. To start the fire again it is necessary onlv to inject more powdered fuel, and tho heat stored up in the brick arch will'be sufficient to ignite it. Ashpit delays are reduced because the intense .beat that, plays on the. finely subdivided and suspended ash precipitates it as slag on to self-clear-ing slag pans. The amount of air is regulated automntically, According to the amount of fuel that j.s being burned, and in this waj - perfect combustion is assured. It will bo understood, of course, that there is no “fire” in the ordinary sense of the term, for as fast as die coal is injected it is consumed. An important advantage that may be be attained with pulverising is that a /Coat winch would' otherwise be worthless can be converted into a comparatively good fuel. A remarkable illustration of this may be seen in what is now being done on the Central Railway of Brazil. There is plenty of coal in Brazil, but tho quality is so poor that before pulverising became practicable it was useless for locomotive purposes. It was necessary, therefore, to import all railway coal. A year or so after the war broke out'the company was paying £8 a ton for their coal, and even at this exorbitant price they could not obtain more than 75 per cent, of their requirements.. But in 1916 firing with pulverised coal was brought to the practicable stage, and it was tried with the wretched Brazilian coal, which may contain as much as 9 per cent, of sulphur and 30 per cent, of incombustible matter. It was Shown that even such coal as this when reduced to powder could be burned with excellent results, and therefore a difficult economic problem that confronted Brazil was solved. The company has now 250 locomotives adapted for the burning of powdered coal.,

Though they have not come to any decision in regard to the use of pulverised oal on the Victorian railway system. Cm commissioners are watching all these developments closely. And in this connection it may be said that it would be extremely interesting to learn whether our brown coal could be made available as a locomotive fuel. It is quite possible that if it were pulverised it could bo burned without tho need of carrying out any costly structural alterations at the fire-box end. As to the pulverised coal sjoker itself, this is quite a simple device. The coal, which is ground hr a separate plant, is loaded into a hopper on the tender, and from the hopper it is driven by an air-blast into the fire-box, tho blast being created by a- turbine driven fan. When starting cold tho turbine and fan are cut- out, and the coal is fed into the furnace by highpressure air stored in a reservoir in the tender. ,11)0 “kindling” is furnished by a piece of lighted waste soaked in oil. With the water in the boiler at 40deg. Fahr. steam can be raised to a pressure of 2001 b. to the square inch in less than an hour.