File:The Street railway journal (1903) (14574987960).jpg

Identifier: streetrailwayjo211903newy (find matches)
Title: The Street railway journal
Year: 1884 (1880s)
Authors:
Subjects: Street-railroads Electric railroads Transportation
Publisher: New York : McGraw Pub. Co.
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Smithsonian Libraries

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ua as measured in inches of mercury. Turbine operating at1500 r. p. m., under a pressure of 140 lbs. of steam, and delivering 600 kw. April ii, 1903.) STREET RAILWAY JOURNAL. 5^7 tlie steam engine it is practically impossible to provide for highdegrees of expansion. As the exhaust pressure approaches aperfect vacuum the volume naturally increases at a rapid rate—the volume of steam with a 29-in. vacuum being double thatwith a 28-in. vacuum. To handle high degrees of expansion itwould, therefore, be necessary to make cylinders of steamengines very large, and this increase of size and weight of parts contact with the steam, and, consequently, condensed water canbe taken from surface condensers and returned to boilers. Theuse of surface condensers under such conditions renders un-necessary the introduction of air either in feed or circulatingwater, and, consequently, makes possible a very high vacuumwith small air-pumping apparatus. The results shown by these curves are obtained from a
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fixes a practical limit, which cannot be passed without exces-sive cost and complication. In the turbine the highest degreesof steam expansion are easily provided for, and consequentlya much larger proportion of the total work in steam can beutilized by turbines than by steam engines. There are other conditions in the Curtis turbine which makehigh degrees of vacuum more easily attainable than they areunder ordinary conditions. The machine is so constructed thatleakage of air into the vacuum chamber is easily renderedimpossible. The leakage of air into condensing engines is con-siderable, and is generally not checked owing to the small valueof improved vacuum to an engine. With turbines of the type here described, no oil comes into COMPARISON OFKW, 100-R. P. M.CROSS-COMPOUNDENGINE AND 500-KW, 1800-R. P. M.CURTIS TURBINE. machine of 6oo-kw capacity, and are naturally inferior toresults which are expected from the very large units which arcnow being built. It is hoped that very soon afte

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