By an improved design Professor R. L. Weighton of Armstrong College, Newcastle-on-Tyne, has doubled the efficiency of the surface condenser, and reduced its consumption of water 44 per cent. In his apparatus the condensing water enters at the base, and leaves at the top, after several circuits instead of but two as in the ordinary condenser. This new apparatus is drained off in sections, instead of allowing the condensed steam to accumulate at the bottom, as in common practice. This sectional drainage is effected by dividing the interior into diaphragms somewhat inclined to the horizontal, so that the water of condensation is removed as fast as formed and does not flow from the upper tubes over those beneath. The gain in this arrangement arises from the fact that the greater part of the condensation takes place in the upper part of a condenser, where the steam impinges first upon the tubes. The Weighton apparatus, in conjunction with dry air-pumps, shows a condensation of 36 pounds of steam per square foot of surface per hour, with a reduction of pressure to one twentieth of barometric pressure (11⁄2 inches as compared with 30), using as condensing water 28 times as much as the feed water, at an inlet temperature of 50° Fahr.
POWER-HOUSE, INTERBOROUGH RAPID TRANSIT CO.,
11th Avenue and 59th Street, New York.
Showing group of Allis-Chalmers steam-engines.
Steam Turbines.
For a long time, and well into the nineteenth century, water was lifted by pistons moving in cylindrical pumps. Meantime the turbine grew steadily in favor as a water-motor, arriving at last at high efficiency. This gave designers a hint to reverse the turbine and use it as a water lifter or pump: this machine, duly built, with a continuous instead of an intermittent motion, showed much better results than the old-fashioned pump. The turbine-pump is accordingly adopted for many large waterworks, deep mines and similar installations. This advance from to-and-fro to rotary action extended irresistibly to steam as a motive power. It was clear that if steam could be employed in a turbine somewhat as water is, much of the complexity and loss inherent in reciprocating engines would be brushed aside. A pioneer inventor in this field was Gustave Patrick De Laval, of Stockholm, who constructed his first steam turbine along the familiar lines of the Barker mill. Steam is so light that for its utmost utilization as a jet a velocity of about 2,000 feet a second is required, a rate which no material is strong enough to allow. De Laval by using the most tenacious metals for his turbines is able to give their swiftest parts a speed of as much as 1400 feet a second. His apparatus is cheap, simple and efficient; it is limited to about 300 horse-power. Its chief feature is its divergent nozzle, which permits the outflowing steam to expand fully with all the effect realized in a steam cylinder provided with expansion valve gear. Another device of De Laval which makes his turbine a safe and desirable prime mover is the flexible shaft which has a little, self-righting play under the extreme pace of its rotation.
A, De Laval nozzle and valve in section. B, Turbine buckets. C, Turbine wheel.
The Parsons Steam Turbine.
Of direct action turbines the De Laval is the chief; of compound turbines, in which the steam is expanded in successive stages, the first and most widely adopted was invented by the Hon. Charles A. Parsons of Newcastle-on-Tyne. From an address of his to the Institute of Electrical Engineers, early in 1905, the following narrative has been taken:—