Improvements in and relating to Water Tube Steam Generators.
Year: 1899

page_text: Date of Application, 13th Jan., 1899-Accepted, 4th Mar.,
1899
COMPLETE SPECIFICATION.
Improvements in and relating to Water Tube Steam Generators.
We, SIMPSON, STRICKLAND & COMPANY, LIMITED, of Dartmouth, South Devon,
Engineers and Yacht Builders, and WILLIAM CROSS, M.I.C.E., of Dartmouth,
South Devon, do hereby declare the nature of this invention, and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement:-
Our invention relates to water tube steam generators of the three-drum type,
and our improvements consist in a particular disposition of certain of the circulat-
ing water tubes, and in a novel arrangement of steam and water separator within
the upper drum, whereby better results in use are obtained. We will describe our
invention in reference to the accompanying drawings in which Fig. 1 is a central
longitudinal section of a generator fitted with our improvements. Fig. 2 is a front
end elevation thereof, partly in section, and Fig. 3 is a back-end elevation. Fig. 4
is a part plan of one of the plates composing our improved separator showing
arrangement of perforations. These drawings illustrate a complete generator,
the general arrangement of which is common and not of our present invention,
and in the following description reference by letter is only made to those parts
included in the improvements which we claim as novel. As will be seen, part of
the water circulating tubes enter the upper drum below the water level therein, and
by our present improved disposition we arrange the two innermost rows of tubes T T¹
to cross and pass between each other centrally over the fire grate and at a short
distance below the base of the upper drum; thus these tubes T T are less steeply
inclined than the rest and are exposed to a maximum of heat, whereby very rapid
circulation results. The furnace gases pass between these crossed rows of
tubes T T and thence expand amongst the outer rows of tubes connecting the pair
of lower drums to the upper drum; all the drums and tubes are enclosed in the
usual outer casing provided with an uptake at its top, and suitable damping
arrangements for controlling the rate of escape of the gases are provided. Refer-
ring to our novel arrangement of steam and water separator within the upper drum.
We employ a two-part separator of which the upper part consists of a hoodlike
curved plate enclosing the main steam pipe which is perforated along its upper
side so as to ensure the entry only of comparatively dry steam. This upper part
is or may be of the construction referred to in Thornycroft's Specification No. 1404
of A.D. 1885, though we may employ any suitable kind. The lower part of the
separator is composed of two or more superimposed curved perforated plates which
are usually made of brass. In the drawings three such plates are shown marked A,
B and C and spaced at suitable distance apart, for example 2 inches, and sup-
ported in any convenient way, for example, by screwed bolts I) and brass distance
pieces d, such as illustrated. Fig. 4 shows in plan a part of one of these baffle
plates and the perforations a a are formed and proportioned as required, for
example, they may be " in diameter and "pitch.
By this arrangement the water projected upwards from the innermost groups of
tubes and particularly from the cross tubes T T¹, strikes against the lower sides

page_text: of these perforated baffle plates with such violence as to be partly forced through
the perforations thereof, and partly to be thrown back by the solid parts of the
plates and thereby the contained steam is effectually separated and rises to the
upper part of the separator in an efficient condition of dryness.
A further and important advantage arising from the above described arrangement
of crossed circulating tubes is that they in great measure shield and protect the
lower part of the upper drum from the intense heat and direct impingement of
flames.
When zines are used as shown for example to the left of the separator in Fig. 1,
the baffle plates A B C are cut away to clear the brackets carrying such zincs.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is:
1. In water tube steam generators such as above referred to, the arrangement
in which the two innermost rows TT of circulating tubes cross and pass between
each other centrally above the fire grate, as and for the purposes herein described
and illustrated in the drawings.
2. The herrin described two-part arrangement of steam and water separator
within the upper drum consisting in the combination with an upper, part such as
is referred to of two or more superimposed curved perforated baffle plates ABC
arranged and adapted to operate substantially in the manner above set forth.
Dated this Thirteenth day of January 1899.