Scientific American Supplement, No. 633, February 18, 1888Various
Science
Scientific American Supplement, No. 633, February 18, 1888
Various
Science -- Periodicals
As each turbine of the set is assumed to give 72.5 per cent. efficiency,
the total number may be assumed to give the same result, or, in other
words, over 72 per cent. of the power derived from using the steam in a
perfect engine, without losses due to condensation, clearances,
friction, and such like. A perfect engine working with 90 lb. boiler
pressure, and exhausting into the atmosphere, would consume 20.5 lb. of
steam per hour for each horse power. A motor giving 70 per cent.
efficiency would, therefore, require 29.29 lb. of steam per horse power
per hour. The best results hitherto attained have been 52 lb. of steam
per hour per electrical horse power, as stated above, but it is
anticipated that higher results will be attained shortly. Whether that
be so or not, the motor has many advantages to recommend it, and among
these is the increased life of the lamps due to the uniform rotation of
the dynamo. At the Phoenix Mills, Newcastle, an installation of 159
Edison-Swan lamps has been running, on an average, eleven hours a day
for two years past, yet in that time only 94 lamps have failed, the
remaining 65 being in good condition after 6,500 hours' service. Now,
if the lamps had only lasted 1,000 hours on the average, as is commonly
assumed, the renewals would have amounted to double the year's cost of
fuel, as at present consumed.
The present construction of the motor and dynamo is shown in the
figures.
[Illustration: Fig. 1 though 6]
Fig. 2 shows the arrangement of 90 complete turbines, 45 lying on each
side of the central steam inlet. The guide blades, R, are cut on the
internal periphery of brass rings, which are afterward cut in halves and
held in the top and bottom halves of the cylinder by feathers. The
moving blades, S, are cut on the periphery of brass rings, which are
afterward threaded and feathered on to the steel shaft, and retained
there by the end rings, which form nuts screwed on to the spindle. The
whole of this spindle with its rings rotate together in bearings, shown
in enlarged section, Fig. 3. Steam entering at the pipe, O, flows all
round the spindle and passes along right and left, first through the
guide blades, R, by which it is thrown on to the moving blades, S, then
back on to the next guide blades, and so on through the whole series on
each hand, and escapes by the passages, P, at each end of the cylinder
connected to the exhaust pipe at the back of cylinder. The bearings,
Fig. 3, consist of a brass bush, on which is threaded an arrangement of
washers, each successive washer alternately fitting to the bush and the
block, while being alternately 1/32 smaller than the block outside and
1/32 larger than the bush in the hole. One broad washer at the end holds
the bearings central. These washers are pressed together by a spiral
spring, N, and nut, and, by friction against each other, steady or damp
any vibration in the spindle that may be set up by want of balance or
Public-domain text, read in full here on John Shaqi.
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