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A 2,250-H. P. TURBINE DESIGNED FOR MARINE AND OTHER SERVICE.
Hamilton Holzwarth Type.-Direct-Connected to 1,000-K. W. Generator.
the vanes by both impulse and reaction. Steam enters at the smaller end of the turbine, expanding parallel to the shaft, its volume gradually increasing and its pressures and temperature decreasing, until, finally, condenser conditions are reached. To accommodate the increase in volume, vanes of increasing length are used; and, when a mechanical limit is reached, the diameter of the spindle is abruptly increased. No similarity, therefore, exists between the three drums of the turbine and the three expansion stages of a triple-expansion engine, as is frequently believed. A much higher degree of expansion of steam is possible in a turbine, and, therefore, a greater economy. The design is very simple, there being no distribution valves, pistons, or connecting rods. To compensate for the small amount of thrust along the axis of the turbine, due to the pressure of the steam against the blades, three revolving balancing pistons are provided at the opposite end of the rotor. These rotate without friction in their casings, and automatically maintain a perfectly balanced condition along the shaft under all conditions of load and pressure. ...The bearings of the turbine and generator are oil-cushioned in order that they may be sufficiently flexible to absorb any slight vibrations occurring when the rotor is passing its critical speed-changing from its geometric to its gravity axis. These bearings consist of a set of loosely fitting bronze sleeves surrounding the shaft and supported by oiled films. They are constantly flushed with oil from a reservoir supplied by a small plunger pump which is operated from the governor shaft.
The steam is controlled by a sensitive centrifugal governor, geared from the turbine shaft and adjustable while running, thus enabling alternating-current generators to be successfully operated in multiple. Steam is admitted in short puffs, the governor varying the period of admission. The automatic adaptability of the turbine to heavy overloads is effected with the aid of a by-pass in the cylinder, through which high-pressure steam may be admitted directly to the second, or middle, drum of bladesthe internal pressure at this point, and therefore the capacity of the engine, be
ing increased. On a decreasing speed, resulting from heavy overloads, the governor opens this by-pass; and, if the speed continues to diminish, the governor shuts off the steam entirely, thus preventing any damage to the turbine or generator.
The foundation for the turbine unit consists simply of ten-inch steel beams spanning a condensing pit. As the velocity of rotation of the turbine is ab
so rapidly that the peripheral distance it traveled, if determined by linear measure, would amount to over 7,000 miles every 24 hours.
The Turbine Pump The application of the turbine to the pumping of water, is also very interesting. The design illustrated represents 58 brake horse-power, and is of the De Laval type, having a steam pressure of
solutely uniform, and no reciprocating forces are encountered, the unit is simply set upon the floor without faster.ings. A
VIEW OF TURBINE AND GENERATOR. complete condensing outfit is installed in
Taken while in operation. the pit, consisting of a surface condenser having 1,500 square feet of cooling sur- 100 pounds. It has actually pumped 250 face, a rotating dry vacuum pump 6 by gallons per minute, representing a total 10 by 10 inches, providing a constant lift of no less than 700 feet. The turbine vacuum of 2512 inches. The condensed pump, however, has been manufactured steam from the turbine flows into a hot in sizes as large as 300 horse-power, withi well at the bottom of the condenser, from a capacity of 2,000 gallons per minute which it is pumped to the boiler.
and 500 feet head. These turbines are
operated both at low pressure and at The Turbo-Generator
high pressure, the low-pressure turbine When it forms a portion of an elec- being of the centrifugal pattern, having trical generating unit, the turbine is usu- turbine and pump mounted on the same ally direct-connected to the generator, as base. The high-pressure pattern works is frequently the case where other forms on the same principle as the low-presof steam or hydraulic power are brought sure pump, and is being placed in service into service. The turbine shown in the for fire protection, for operating hyaccompanying illustration was connected draulic elevators, and in municipal waterwith a generator having a rated capacity works. of 400 kilowatts, and was capable of delivering a three-phase alternating current
The Machine Shop Turbine of 440 volts, the number of alternations As already stated, the turbine is now being 7,200. As an indication of the taking its place in the shop for driving service provided by this type of turbine, power tools of various kinds. In most it may be said that it actually revolved instances, power is communicated by
means of a rope or belt drive; and the turbine, the one shown being connected machine shop turbine is now manufact to an electric generator representing ured in sizes developing as high as 300 5,000 kilowatts. This is of the Curtis horse-power, with a steam pressure vary- design, which has found favor in the ing from 60 pounds to 300 pounds. The equipment of street-railway power stasmall amount of space required for the tions, in plants for electric lighting, and installation of the turbine as compared for other uses in large cities. In this de
with other forms of steam power, has sign a moderate rotative speed is percaused it frequently to be preferred by mitted, as the turbine is divided into steam users where floor space is limited; stages each of which contains one, two, but it can be employed in vertical as well or more revolving buckets supplied with as horizontal designs.
steam from a set of expansion nozzles. The Vertical Turbine
Consequently the nozzle velocity in each The accompanying illustration gives an stage is reduced. Under this arrangeidea of the compactness of the vertical ment, the energy of the moving steam