. The street railway review . an air pump which uses steameconomically and the compound fan engines, which arc also ccononri-ical machines. The heaters taking steam from these auxiliaries will,by taking water from the hot well at about 95°, raise its tempera-ture to 170° or 180°. In this station, in addition to exciting themain generators, the exciter unit would be called upon to furnishcurrent for all the electrical requirements of the station, such aslighting svstem, circulating pump, motors, air compressor, blast fanfor transformers, crane, coal handling machinery and for motordriven tools
. The street railway review . an air pump which uses steameconomically and the compound fan engines, which arc also ccononri-ical machines. The heaters taking steam from these auxiliaries will,by taking water from the hot well at about 95°, raise its tempera-ture to 170° or 180°. In this station, in addition to exciting themain generators, the exciter unit would be called upon to furnishcurrent for all the electrical requirements of the station, such aslighting svstem, circulating pump, motors, air compressor, blast fanfor transformers, crane, coal handling machinery and for motordriven tools in the adjacent shop. Thus it is seen that the exciterengine would carry more load and so deliver more exhaust steamthan the heater could condense, which would allow much of thesteam to waste to atmosphere. This plant will use economizers,and so there will not be much advantage in delivering high tem-perature water from the heaters to the economizers, because theeconomizers will raise water more degrees in temperature when. FIG. 52. receiving low temperature water than when receiving water of hightemperature. In other words, the capacity and utility of an econ-omizer diminishes as the temperature of its feed water is increased,and the greater amount of work asked for Jrom the economizerthe better paying investment it will be. An active circulation is notprovided for in the general design of economizers on account ofpractical difficulties, and as actual experiment has demonstratedthat twice as much heat is delivered to water circulating at the rateof 3 ft. per second as is delivered to it without circulation, it maybe seen that the commercial value of an economizer would be in-creased greatly if the advantages of free circulation were pro-vided for. If the plant were supplied with economizers it would be aneconomical plan to deliver all the steam to the heater that it wouldcondense, exhausting such machines as are economical in the useof steam into the condensers and such mac
Size: 2016px × 1239px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., book, bookcentury1800, bookdecade1890, booksubjectstreetrailroads
