Improvements in and relating to Mechanisms for Automatically Supplying the Feed-water to Steam-boilers.
Year: 1890

page_text: COMPLETE SPECIFICATION.
Improvements in and relating to Mechanisms for Automatically
Supplying the Feed-water to Steam-boilers.
I, CHARLES BARTLETT BOSWORTH, a citizen of the United States of America
residing at Everett, in the County of Middlesex and State of Massachusetts, one of
the United States of America, Gentleman, 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:-
The invention relates to the art of automatically controlling the action of steam
pumps used in supplying water to steam boilers so that the water within the boiler
shall be maintained at any desired height irrespective of the pressure within the boiler
or the weight of water evaporated, and consists in improvements on this class of
apparatus and more especially on the apparatus shown and described in Lotters Patent
of the United States of America, granted to me under date of January Fifth, 1886,
No. 333,817.
In the Letters Patent referred to the valve for regulating the pressure of the air
from the air pump, as it flows into the air chamber of the governor is located at the
top of the air chamber.
According to my present invention I locate this air valve at the steam boiler (to be
supplied by the steam-pump,) at the end of a pipe connected with the air-pump, and
with the air-chamber; and my invention consists in part in the means provided for
automatically controlling such air valve and thereby regulating the action of the steam
pump. My invention consists in other improvements and modifications in construction
and arrangement of devices or mechanisms, as will hereainfter appear.
Referring more particularly to Figures 1 to 6 inclusive :-
Figure 1 represents, in elevation, the diaphragan air pressure chamber, A, in its
connection with the throttle-valve, B, of the steam pump, and the pipe, C, to convey
the compressed air from the air-pump, b, into the chamber, A, by means of the pipe, D,
the construction and arrangement of said devices being substantially as shown and
described in Figure 1 of the drawings of my Letters Patent before referred to.
Figure 2 represents, in elevation, a rectangular framework of tubes to be attached
to the steam-boiler, so that the steam and water of the boiler shall enter within said
tubes, and by their expansion and contraction cause the air valve, E, attached thereto,
to open or close as may be required. This rectangular framework of pipes, beginning
at the air-valve, E, Figure 2, is connected with the air pressure chamber, A, Figure 1,
by means of air-pipe, F, G, H, D, and with the air-pump by air-pipe, F, G, H, C.
The tubes, I, J, and K, are of brass, and the connecting rods, L, and M, are of iron.
The rigid arm, N, and lever, O, are of solid brass.
Figure 3 in sectional elevation, represents (full size) the air-valve, E, air-valve.
pipe, F, and a part of the vertical air-conveying pipe, G.
Figure 4, in longitudinal vertical section, represents, (full size) a modified
arrangement of the expansion tabe, from which equally good results may be
obtained, while the device is at once more compact and more easy of construction and
application.
In this arrangement, the expansion tube, P, having its outer end closed, is screwed
into the bored socket, Q, the end of which, at R, is screwed into the steam-boiler, at a
proper water level. Within the expansion tube, P, the smaller steam circulating
tube, S, of a little less than half the diameter of the former, is brazed to the upper
part of the socket, both ends being left open, and one end projecting within the boiler,
as shown. To the bottom of this expansion tube, P, which is of brass, or other
suitable metal, is brazed the bar or strip of iron, T, which being of unequal expansion
with brass, produces, under the influence of changing temperatures, upward and

page_text: downward deflections of the free end of the tube, by means of which the air-valve U,
is operated. The expansion tube, P, and the air-valve regulating-screw, V, are
inclosed within the cylindrical case, W. And the air-pipe leading to the governor is
shown at X.
Figure 5 is a transverse vertical section through a-b, Figure 4, showing the appli-
cation of the iron bar, T, to the expansion tube, P, and the relative position therein of
the small tube, S.
The attachment and mode of operation of the several devices are as follows, and will
be explained with reference to Figure 6.
The motion for the air pump is derived from any convenient reciprocating or other
moving part of the steam-pump, by which it is duly operated. The rectangular
framework of tubes to which is attached the air-valve, E, may be connected to the
boiler by attaching the end of the upper tube, I, at a point above the highest water
level, and by attaching the end of the lower tube, K, to the middle water-gauge
connection. In this way, steam will always he present in the upper tube, and water
in the lower tube-if it is desired to maintain the water in the boiler to this height.
In this condition there will be a different degree of expansion of the two tubes, the
upper one being of a greater degree than the lower one, owing to a difference of
temperature. The upper tube will remain substantially constant, both as to tempera-
ture and expansion, while the lower one will be modified by the constantly diminishing
temperature by radiation of the heat from the water confined in the tube. When the
water in boiler falls below the lower tube, then the water in the latter flows into the
boiler, and being replaced by steam the tube expands rapidly under the greater
temperature.
Now when the water in the boiler is above and fills the lower tube, K, the air-
valve, E, is closed; and the air forced by the air-pump into the pipe to which it is
attached, acts also upon the piston or diaphragm, A, in the air chamber of the governor,
and compressing the spring of the governor, duly closes the throttle-valve, B, of the
steam-pump. If the water falls below the lower tube, K, and steam flows into it,
then, the tube expanding under the increased temperature, opens the air-valve, E, by
means of the iron rod, L, and the lever, O, pivoted on the expansion pipe, K, and iron
rod, M, as shown. _ The vertical bar, N, is solid and wholly without movement either
in the pipe, F, or K.
The air-valve, E, having been opened, as described, the air from the air pump flows
outward through it, and the spring of the governor being thereby released, draws
the steam throttle-valve upward, duly opening it for the admission of steam to the
pump, and setting it in motion. As the pump fills the boiler, and also the lower tube,
the lowering temperature of the inflowing water contracts the latter, and thereby
closes the air-valve. By this means, as shown, the air from the air-pump then
acts upon the piston or diaphragm of the governor, giving motion to the steam-pump.
At Figure 6 is shown, in elevation, my feed-water regulating device, as connected
with the steam boiler, a, by pipes, I, and K, and with the air-chamber, A, by
pipes, G, H. D, and with the air-pump, b, by pipes, G, H, C. Steam is conveyed
from the boiler to the steam-pump throttle-valve, B, by pipe c, and through stand-
pipe, d, into the valve-chest of the pump. The air-pump operated by lever, e,
mounted on the steam-pump rock-shaft. From the pump the feed-water passes
through pipe, f, into the boiler.
Instead of using the rectangular framework of tubes shown at Figure 2, for
actuating the air-valve, I sometimes employ the modification shown at Figures 4 and 5,
where its arrangement and operation are explained, and will be readily understood.
Referring now more particularly to Figures 7 to 11 in which I have shown a
modified arrangement of apparatus:
Figure 7 is a side elevation in which the several devices employed are shown in
combination; viz., the steam boiler, A, the steam feed pump, B, with its throttle
valve, C; the air pump, D, which is mounted on the feed pump, B, and receives its
motion therefrom; the air pressure governor, E, and the thermostat, E¹.
Figure 8 is a top view of the air pressure governor, E, and

page_text: Figure 9 19 a vertical section through the axis of the governm
Figure 8, and
Figure 10 is a similar vertical section through the axis of the instrument on the
line a-b, Figure 8, showing how the air pressure is introduced into the piston
chamber of the governor.
'
Figure 11 is a modified shape of the thermostatic tube.
the
Secured to the boiler, A, is the usual water column, M, the sight glass of which is
removed so as to clearly show the thermostat. Attached to this water column
thermostat, El, an enlarged view of which, though of somewhat changed shape, is
shown in Figure 11. This consists of an expansion tube, e, having a pipe, e', for
connection at the top with the water column, and the pipe, e, at the bottom for a
similar connection.
is the
The form shown at Figure 11 presents an arrangement of parts, in which, e,
expansion tube having a pipe connection at either end, the upper one, G, leading to
the steam space, and the lower one, H, to the water space of a steam boiler; these
pipes being so attached that the proper water level of the boiler will correspond to the
longitudinal axis of the tube, e, the water rising and falling in tube, e, conformably to
the rise and fall of the water in the boiler; the water entering through pipe, H, and
the steam through pipe, G.
The right hand branch of the piece, I, is closed by a plug having a forked
standard, J, projecting outward from it, providing a carrying pivot for the lever, p,
the lower end of which is connected by the tension rod, t, to a fixed collar, f, at the
opposite end of the tube, e. The upper end of the lever carries a set-screw to
regulate the operation of the valve, j, under the action of the expansion tube.
In the form at Figure 11, the spring, e, shown in Figure 7 is omitted; the strain
on lever, p, and tension rod, t, being governed by a set-screw q.
In Figure 7 is shown the connection of the thermostat with the pump and throttle
valve governor. The pipe, n, leads from the valve, j, by the pipes, 6, to the pump, D,
and to the air pressure governor, E.
As shown in Figures 8, 9 and 10, the upper part of the air pressure governor, E,
is divided by a horizontal partition, a', into two chambers, the lower one, d', being
occupied by a cylindrical piston, e', and the upper one by the annular piston, f¹.
These two pistons are connected together by the central stem, g', and yoke, h¹. The
upper cylinder contains oil, and acts as a dash pot, to prevent a too rapid movement
of the working parts when called into action. The space between the under side of
partition, a', and the top of the cylindrical piston, e', contains compressed air supplied
by the air pump, D, which is mounted upon the steam pump, H, and from it receives
its notion. The compressed air is conveyed to cylinder, d', by the pipe, b1, b₁, bl, b₁,
and by a branch of this pipe, shown at, n, n, n, it is conveyed to the air relief valve, j,
of the thermostat.
The air pressure governor, E, is mounted upon the top of the throttle valve casing
of the steam pump, and governs the opening and closing of that valve, which is
connected with the piston, e¹, by a screw ended rod, which is enclosed in a strong
spiral spring, , the tension of which may be modified by means of the screw nut, j
At its lower end the spiral spring rests on the top of the packing box of the throttle
valve spindle, k. It will be understood that the downward pressure on the piston of
cylinder, d, and the upward force exerted by the spiral spring, , are in direct
opposition. The pipe, K, K, and K', conveys steam from the boiler to the steam
pump; and the pipe, I, conveys the feed water from the steam pump to the boiler.
The set-screw,
, is to modify the passage of the oil, by the piston, ; and the pet
cock, c, on the pipe, 61, is to modify the air pressure within the air pipes, as may be
desired.
The operation of the combined devices herein described is as follows:
The steam pump, B, having been put in motion, the air pump, D, connected
therewith begins to force air into the pipes, 6', and into the chamber, d¹, above the
piston, e¹. As the air pressure accumulates in the chamber, d¹, the piston, e¹, is
pressed downward against the expansive force of the spiral spring, i, and the throttle

page_text: valve, C, of the steam pump being thereby partly closed, the movement of the steam
and air pump pistons is correspondingly retarded.
If the steam pump is working too slow, the water line of the boiler will be
lowered, so that the water in the expansion tube, e, will run into the boiler and be
replaced by steam, which will expand the tube longitudinally, causing an outward
movement of the upper end of the lever, p, which will open the air relief valve, j,
letting air escape; when, under the resilient action of the spiral spring, ³, the
piston, e, will rise, opening the throttle valve of the steam pump and accelerating its
motion.
If the steam pump is working too fast, the water line of the boiler will rise, so that
steam contained in the expansion tube, e, will be expelled therefrom by the incoming
water, which will be cooled by radiation from the metal of the tube and will contract
longitudinally, permitting the spring, r, to hold the air relief valve, j, to its seat,
preventing the escape of air from the pipes, b₁, and, n, and chamber, d¹, of the
governor. The air accumulation in chamber, d¹, will now press down the piston, e¹,
against the resilient force of the spiral spring, partly closing the throttle valve of the
steam pump, and retarding its motion.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :
1. The employment in combination with a steam pump for feeding water to steam
boilers and with an air pump attached thereto and operated thereby, and with a
diaphragm or piston chamber for the reception of the compressed air therefrom and
located over the throttle valve of the steam pump and connected therewith by a rod
operated by said diaphragm or piston, of an expansion tube at the steam boiler,
connected at its ends with the interior of said boiler, the lower end at a proper
water level, so that any longitudinal movement of this branch of the expansion tube
arising from change of temperature within it (as from its alternate occupancy by
steam or by water), is transmitted so as to operate upon the air escape valve situated
at the boiler end of the air pipe and connected at its other end with the air chamber
and air pump, through the action of which the air pressure in the connecting pipes
and air chamber is maintained and the throttle valve duly regulated, as shown and
described in reference to Figures 1 to 6.
2. The employment of the tubular thermostat opening into the boiler at its inner
end and closed at its outer end and having the tube, S, and valve, U, as described in
reference to Figure 4.
3. The arrangement and use of the expansion tube and boiler connections therefor,
the air valve, the air valve lever and the mechanism for connecting the said air valve
with a throttle valve governor, substantially as described in reference to Figures 7
to 11.
Dated this 1st day of December 1890
.cember
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.