FEED WATER TROUBLES.
Seeking a Remedy.
Owing to the highly mineralised feed water on a section of 400 miles that is supplied to the locomotives running on the overland railway, the cost of boiler maintenance has from the first been ex- cessively high. In some cases it has amounted to £800 a year for each boiler, and though the life of locomotive boilers should be 25 years, it has been necessary to condemn them after they have had only five years of service. Apart from a heavy addition to the working expenses due to this cause, the dislocation of traffic through engine failure has been a source of anxiety.
From the inception of the railway no efforts have been spared to discover some way of making innocuous the corrosive
water obtained from the bores sunk in the long section referred to. Samples have been submitted for analysis to leading chemists in Great Britain, France and Germany, but the reports have always been that no treatment commercially possible was available for getting rid of the mag- nesium chloride which is the destructive agent in this water, and is the cause of 98 per cent. of the trouble. For years the commissioner if Commonwealth Railways (Mr. N.G. Bell) has tried almost every known boiler compound, but while these have reduced the deposit of scale caused by other mineralised matter held in solu-
tion, not one has had any effect on the magnesium chloride. So acute did the position become that the expedient of erecting, at great expense, plants for the distillation of the bore water was seriously considered, though the distilled water would have cost 21/ for 1,000 gallons.
Mine Chemist's Process.
Some time ago Mr. Bell learned that
the Sons of Gwalia mine water similar in quantity to that obtained from the bores along the overland railway was being treated successfully by a process improved upon by the chemist of the company (Mr. Edquist). Compared with the pressures employed for locomotive work, however, those on the boilers at the mine were com- paratively low, and there was no cer- tainty, therefore that the treatment would be equally successful in both cases. More- over, though the matter had become ex- tremely urgent, a treatment plant using the Edquist process would take some time to erect, and it might not be successful after
It would be possible to get rid of all feed water troubles on the overland railway by substituting for the steam locomotives internal combustion locomotives of the Diesel type, which, though still in an ex-
perimental stage, are being used tenta- tively in the United States. An alterna- tive was to try the turbo-condensing type of steam locomotive which is making some headway in the railways of Europe and Great Britain. In it the exhaust, instead of being discharged into the atmosphere, passes into a condenser where it is re- converted into water; it will be seen there- fore, that a condensing locomotive would use distilled water and would use it over and over again. Apart from the fact that both these types must still be regarded as being in the experimental stage, they have the additional disadvantage of being very c0stly, for the cost of either would be about twice that of a standard steam loco- motive of equal power. In the circum- stances however, Mr. Bell thought it worth- while to send abroad the chief mechanical engineer of the Commonwealth Railways (Mr. Gahan) that he might acquire first- hand information about Diesel and con- densing steam locomotives, and also study the latest processes of water softening in use. Mr. Gahan recently returned and has presented his report.
While Mr. Gahan was away, however, an experimental plant, in which the Ed- quist process is employed, was erected at the "362 miles" station, and this has been in operation for some months. The pro- cess consists in treating the water with caustic lime and pulverised barium carbon- ate. This is carried out in an "agitating" tank, where the lime and barium carbonate are slowly stirred into the water for 12 hours. The water so treated then passes into a settlement tank, where, owing to the chemical reaction produced by the barium-lime mixture, this together with the mineral matter that has been held in solu-
tion sinks to the bottom of the tank. All the calcium chloride is got rid of in this way, and also the greater part of the other minerals. Only the sodium chloride (com mon salt) remains unaffected, but this is of little consequence as it is harmless and it can easily be blown out of the boiler as it accumulates. The treated water is now supplied to a number of locomotives, and in the case of two of the boilers exact tests are being made. Plaster casts of the boiler plates were taken to ascertain the amount of corrosion and "pitting" that existed at the beginning of the tests; later other casts were taken, and the two sets were compared. The comparison shows that there has been no increase in the pitting and corrosion, and that there is a noticeable absence of scale formation. There was, indeed, a slight deposit on the crown sheet, but this is what is known as
"egg-shell" scale, which can be removed without trouble with a scraper. The cost of treating the water amounts to 4/6 for 1,000 gallons. It should be added that the barium carbonate process is not new, but,
in its original form its cost was so high that it could be employed only in excep- tional cases. The novelty that Mr. Ed- quist has introduced is the grinding of the solid mineral into a fine powder, and then stirring this slowly into the water.
At the present stage Mr. Bell is not prepared to state definitely that the water trouble has been overcome permanently. Before that can be ascertained tests over a considerable period will have to be car- ried out. The results obtained so far, however, are regarded as highly encourag-