Steam, Its Generation and UseBabcock & Wilcox Company
History
Steam, Its Generation and Use
Babcock & Wilcox Company
Steam-boilers, Water-tube
Draft Regulation--As the capacity of a boiler varies with the combustion
rate and this rate with the draft, an automatic apparatus satisfactorily
varying this draft with the capacity demands on the boiler will
obviously be advantageous.
As has been pointed out, any fuel has some rate of combustion at which
the best results will be obtained. In a properly designed plant where
the load is reasonably steady, the draft necessary to secure such a rate
may be regulated automatically.
Automatic apparatus for the regulation of draft has recently reached a
stage of perfection which in the larger plants at any rate makes its
installation advisable. The installation of a draft gauge or gauges is
strongly to be recommended and a record of such drafts should be kept as
being a check on the combustion rates.
An important feature to be considered in the installing of all recording
apparatus is its location. Thermometers, draft gauges and flue gas
sampling pipes should be so located as to give as nearly as possible an
average of the conditions, the gases flowing freely over the ends of the
thermometers, couples and sampling pipes. With the location permanent,
there is no security that the samples may be considered an average but
in any event comparative results will be secured which will be useful in
plant operation. The best permanent location of apparatus will vary
considerably with the design of the boiler.
It may not be out of place to refer briefly to some of the shortcomings
found in boiler room practice, with a suggestion as to a means of
overcoming them.
1st. It is sometimes found that the operating force is not fully
acquainted with the boilers and apparatus. Probably the most general of
such shortcomings is the fixed idea in the heads of the operatives that
boilers run above their rated capacity are operating under a state of
strain and that by operating at less than their rated capacity the most
economical service is assured, whereas, by determining what a boiler
will do, it may be found that the most economical rating under the
conditions of the plant will be considerably in excess of the builder's
rating. Such ideas can be dislodged only by demonstrating to the
operatives what maximum load the boilers can carry, showing how the
economy will vary with the load and the determining of the economical
load for the individual plant in question.
2nd. Stokers. With stoker-fired boilers, it is essential that the
operators know the limitations of their stokers as determined by their
individual installation. A thorough understanding of the requirements of
efficient handling must be insisted upon. The operatives must realize
that smokeless stacks are not necessarily the indication of good
combustion for, as has been pointed out, absolute smokelessness is
oftentimes secured at an enormous loss in efficiency through excess air.
Public-domain text, read in full here on John Shaqi.
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