The New Zealand Railways Magazine, Volume 6, Issue 7 (February 1, 1932.)

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227 Years of Progress.

Experiments in the production and application of superheated steam can be traced back as far as the year 1705. It is, to-day, universally recognised, however, that Dr. Wilhelm Schmidt, of Kassel, Germany, whose investigations extended over a period of forty years, is the pioneer of practical superheating.

In 1898 Dr. Schmidt started the commercial application of superheaters to railway locomotives, the first superheated engines being placed in service on the Prussian State Railway. It is from that date that the practical history of superheating commences.

Early locomotive superheaters, which were of the smoke-box type, achieved only a moderate degree of success, the total number of engines fitted being less than 150.

In 1902, however, Dr. Schmidt introduced his Smoke Tube Superheater, which proved so successful on the Continent, that, in 1908, the Schmidt Superheating Company, Limited, was formed for the purpose of developing the use of this design in Great Britain.

In 1910 the progress which had been made by Dr. Schmidt in Europe resulted in the formation of The Locomotive Superheater Company (now The Superheater Company) in the United States, in order to develop the use of his apparatus in that country.

The Schmidt Superheating Co., Ltd., was reorganised in 1919, and renamed the Marine and Locomotive Superheaters Ltd., and, finally, in 1924, after amalgamation with the Superheater Corporation, Ltd., assumed its present title of The Superheater Company, Ltd.

In the early days of practical superheating only moderate final steam temperatures were employed, particularly in the case of Marine and Stationary Reciprocating Engines, about 550 deg. F. being the maximum temperature in this class of work.

In the case of locomotives, temperatures were somewhat higher and, for a time, progress in superheating was largely confined to this field.

The introduction of the turbine gave a further great impetus to the use of superheated steam for Stationary Engine work and the advantages of higher final temperatures were recognised.

This demand for higher superheat has persisted, and, at the present time, the use of steam at 900 deg. F. is proposed in one or two large plants now under construction; while a number of plants are in actual operation with steam temperatures exceeding 800 deg. F. at the superheater outlet. In locomotive and marine work there is a similar trend in development.

In addition, higher steam pressures are also being employed, and at the same time revolutionary changes in boiler design and methods of firing are taking place.