Improved Automatic Feed Water Regulator for Steam Generators and the like.
Year: 1897

page_text: Date of Application, 3rd Dec., 1897-Accepted, 15th Jan.,
1898
COMPLETE SPECIFICATION.
Improved Automatic Feed Water Regulator for Steam Generators
and the like.
I, SETON BROWN, of 29, Seymour Street, Portman Square, London, W.,
Engineer, 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:-
-
My invention relates to that description of automatic feed water regulator
wherein a valve controlling the supply is actuated by the expansion and con-
traction of a metal bar or tube. In such apparatus as heretofore constructed for
directly controlling the supply of feed water the said expansion tube has been so
arranged as to be subject only to the difference in temperature between the water
and the steam in the same boiler, and this difference being comparatively small,
the apparatus is not sufficiently sensitive to insure a proper regulation of the feed
according to slight variations in the water level of the boiler.
According to my invention I so construct such automatic feed apparatus that
the expansion tube is exposed externally to the fire heat, a rapid circulation of the
water being effected through it when the water is at the normal level in the boiler,
thus preventing any considerable heating and consequent expansion of the tube
at that time, while when, by reason of the sinking of the water level, the tube is
more or less emptied of water and filled with steam, it becomes heated to a more
or less considerable degree, so that by the consequent considerable range of expan-
sion and contraction, a very sensitive control of the feed admission valve is
ensured, enabling the normal water level to be maintained in a very effective
manner.
The above described feed apparatus can be modified in various ways in carrying
out the above described main feature of my invention; by way of example I will
describe the constructions which I prefer to employ, referring to the accompanying
drawings, in which Figure 1 shews a broken longitudinal section of one con-
struction of the apparatus, Figures 2 and 3 shew enlarged cross sections taken
respectively at XX, and at Y Y Figure 1. Figures 4 and 5 shew respectively a
sectional plan and a sectional elevation of a modified construction.
C is the tube, by the expansion and contraction of which the valve D which con-
trols the supply of feed water to the boiler is actuated. The tube C is placed
within the fire casing of the boiler, the ends being however situated outside; it
is arranged at the desired height of the water level, slightly inclined to the
horizontal and connected with the water space of the boiler at A and with the
steam space at B. The tube C is secured at one end to the casting E which is con-
nected by the adjusting screw F to the valve D, and at the other end it is secured
to the casting G.
Within the tube C is a smaller tube H of the same diameter as the feed pipe,
also secured at one end to the casting G and at the other end to the valve seat d.

page_text: The pipe from the feed pump is connected with the inner tube H at I; thus
the tube H having feed water constantly pumped through it remains at a fairly
constant temperature and constant length.
The annular space between the tubes C and H, being connected at A with the
bottom of the boiler by a tube protected from the fire, is filled with more or less
water according to the level of water, in the boiler, and being slightly inclined it
permits the steam generated in it to escape to the steam space through the
branch B.
The feed water, after having passed the valve D is carried to any part of the
boiler desired, bynalpipe connected at Mi to the casting E. The pipe connections
at A and M are of such a form as to allow a slight flexibility in the direction of
the tube C.
The action of the apparatus is as follows: When the water level is above the
upper end of the tube C, there is a continuous circulation of water-through the
annular space, so that nearly all the heat from the fire is absorbed by the water
therein and under this condition the tube Cis of such a temperature and length
that the valve D is closed. When the water level falls, there will be less, water
in the annular space to absorb the heat from the fire, and the tube C will expand,
opening the valve D: Thus it will be seen that the amount of valve opening varies
with the amount of water in the annular space between the tubes C and H and
consequently with the water level in the boiler.
The adjusting screw 1 enables the valve to be opened when the boiler is cold,
and, when working, to admit more or less feed for a given water level according to
the rate of evaporation required, a pointer J. being fitted to mark each position.
It is expected however that the same adjustment, will suit every rate of evapora-
tion, as, the fiercer the fire, the more the tube C will expand for the same amount
of water within. it.
'
J
But it must not be supposed that the admission of feed depends entirely on the
heat of the fire; it depends on the amount of water present to absorb whatever
heat the fire may have. The primary object of exposing it to the fire is to increase
its rapidity of responding to any fluctuation of water level.
For the tube C, a "Serve" tube is preferred as giving greater stiffness against
buckling to both. tubes C and H;, but any other form of tube may be employed
if it gives the necessary stiffness and margin of safety against deterioration by
heat. It is preferably made of mild steel, so as to be able to stand high tempera-
tures without loss of strength, but any other metal may be employed if considered
suitable.
J
A
The valve shewn in the drawing is of the annular type, to give a large area of
passage with a very small lift. When open it is kept against the nut K on the
spindle F by the pressure from the feed pump and a spring, as shewn, but when
against its seat d it is unaffected by any further contraction of the tube C as the
spindle F can slide through it in the direction in which the tube C contracts.
thin corrugated metal diaphragm L,serves as a water tight partition allowing of
the relative movement of the two tubes C and H. Though this particular type of
valve is preferred, any other approved type may be used in connection with. this
apparatus.
}
:
If desired, the movement due to the expansion may be multiplied by one or
more levers, external or internal, adjustment being effected by altering their
fulcrum:
d
.11.
Figures 4 and 5 shew a modification in which the valve (1) consists of a flat
plate perforated with a number of small holes corresponding to similar holes in
the valve seat (2).,
A cap (3) secured to the end of the inner tube carries a pin (4) on which the
valve is made to partially rotate as the outer tube expands, by a pin (5) carried
by the casting (6) to which the outer or expansion tube C is secured, the pin 5 in
moving with C, being thereby made to change its position relatively to pin 4
TI

page_text: For adjustment, a screw (7) carried by 6 actuates a lever (8) turning a shaft (9)
at the end of which is a crank (10) carrying the pin (5) mentioned above.
The partial rotation of the valve opens or closes the holes (which are placed at
as great a radius as is convenient, in order to obtain a greater travel), thereby
increasing or checking the supply of feed water which passes out through the
branch (11) connecting the space below the seat 2 with the boiler. The apparatus
is otherwise constructed and operates in the same manner as described, with
reference to Figures 1, 2 and 3.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
-
1. Apparatus for regulating the feed water supply of boilers wherein a tube
placed in a position slightly inclined from the horizontal at or about the normal
water level of the boiler, is subjected externally to fire heat, while its interior is
connected at the lower end to the water space of the boiler and at the higher end
to the steam space thereof, the said tube being so arranged in combination with
a valve which directly controls the admission of feed water to the boiler, that on
the greater or less expansion or contraction of the tube consequent on the variation
of the water level, it effects the opening or closing of the valve to a greater or less
degree, substantially as described.
2. Apparatus for regulating the feed water supply of boilers, consisting of an
outer tube exposed externally to fire heat, and having its ends connected respec-
tively to the water space and steam space of the boiler, and an inner tube
connected at one end to the outer tube and communicating with the feed water
supply, the other end of such inner tube being unconnected with the outer tube
and having its opening closed by a valve which is opened or closed by the expan-
sion and contraction of the outer tube, in order to control the flow of the feed
water through the inner tube to a channel leading to the boiler, substantially as
described.
.
3. Apparatus for regulating the feed water supply of boilers, constructed and
operating as herein described with reference to the drawings.
Dated this 3rd day of December 1897
ABEL & IMRAY,
Agents for the Applicant.