Improvements in and connected with Water-tube Steam Boilers.
Year: 1894

page_text: Date of Application, 13th Apr., 1894
Complete Specification Left, 16th Jan., 1895--Accepted, 2nd Mar., 1895
PROVISIONAL SPECIFICATION.
Improvements in and connected with Water-tube Steam Boilers.
We, JAMES WEIR, GEORGE WEIR, and JOHN RITCHIE RICHMOND, all of
Holni Foundry, Cathcart, in the County of Renfrew, North Britain, Engineers, do
hereby declare the nature of this invention to be as follows, that is to say :-
Our said invention relates to water-tube steam boilers of kinds in which steam
is generated in the tubes and passes thence to a steam space carrying water with
it, there being continuous circulation of water through the tubes; and our object
is to improve the action and increase the efficiency of such boilers, our invention
comprising automatic and other arrangements for preventing the tubes from being
injured through the expulsion of water from them which is liable to occur in
certain circumstances.
In boilers to which our improvements are applicable the tubes are subjected to
fire heat and constitute the principal heating surfaces, the water entering their lower
ends, passing through them in an upward or generally upward direction, and being
delivered. along with steam from their upper ends into cylindrical or other shells
in which the steam space is contained. The water not converted into steam passes
down again to the lower ends of the tubes through one or more descending
passages or spaces. The water level may be above or below the upper ends of
the tubes.
From experiment and from comparison and consideration of data thereby obtained
we have learned that the rate of circulation through the tubes of a given boiler
with a given normal water level and with a given rate of evaporation per unit of
heating surface, depends on the pressure of the steam. Thus if with the maximum
pressure the circulation is such that the water in the upper parts of the tubes does
not become so much diminished or mixed with so much steam that the tubes get
overheated and injured, but if, whilst other conditions remain the same, the steam
pressure becomes reduced (through a temporary increased consumption of it in the
engines or through other causes) then the steam as it is being formed, in the tubes
assumes a larger volume because of the diminished pressure, and in passing out of
the upper ends of the tubes bas less water mixed with it, with the result that the
tubes become more or less overheated and injured.
By our invention we prevent injurious diminution of the pressure, and may adopt
various appliances and arrangements for that purpose.
According to one modification we apply a valve in the pipe or passage through
which the steam passes on its way from the boiler. This valve may be a simple
plunger or piston working through a stuffing box and externally loaded, preferably
by means of an adjustable spring acting directly or through one or more levers.
Or, for large sizes, the valve may be a double-beat valve having fixed to it a
plunger of comparatively small size working through a stuffing box and externally.
loaded. When the steam pressure in the boiler gets below the predetermined
amount the passage becomes closed by the action of the spring or other load on
the valve or plunger against which the boiler pressure directly acts.
According to another modification a large valve to close when the boiler pressure
gets below the predetermined amount, is in the form of an inverted cylindrical
cup working upon an inner fixed cylindrical piece which piece has formed centrally
in it a small cylindrical chamber having working in it a plunger subject to the
upward pressure of the boiler steam. The main valve has a tubular stem passing

page_text: '
upwards and out through a stuffing box, and through this tubular stem but not
filling it, extends a rod fixed to the plunger. A spring-loaded lever acting on the
plunger rod tends to keep the plunger down, but when the boiler pressure is
adequate it presses up the plunger and opens the main valve, a flange on the plunger
rod then closing the bottom of the tubular stem. On the pressure getting too low
the plunger descends and the flange on its rod uncovering the bottom of the
tubular stem allows steam to escape through the stem from the space between the
top of the main valve and the inner fixed piece on which it works, in consequence
of which the main valve closes.
Either along with or instead of valves such as are herein before described for
controlling the main delivery of steam we may use a separate pipe connected with
alarm or other apparatus, such pipe being provided with a valve arranged to open
only when the internal steam pressure gets below the proper amount, the valve
being such as to close with the steam pressure and being connected to a plunger or
diaphragm which is loaded to the proper amount in a manner to open the valve
when the steam pressure gets too low.
According to another modification which may be used by itself or along with
anything hereinbefore described, we provide a storage vessel to contain a quantity
of water in a highly heated state such vessel being in communication at its upper
part with the pipe through which steam passes on its way to the engines. Some
of the steam from the boiler is led by a branch pipe to the bottom of the storage
vessel and in passing through the water therein maintains it at a high temperature.
When a reduction in the steam pressure occurs the highly heated water in the
storage vessel will contribute a quantity of steam which will prevent the pressure
from getting so low as it otherwise would do. A regulating valve should be
provided on the pipe supplying steam to the bottom of the storage vessel; and
there may be one also on the steam pipe between the boiler and the top of the
storage vessel.
The water in the storage vessel may serve as reserved feed water; and other
vessels or tanks for feed water may be made smaller or dispensed with.
↑
In water-tube boilers worked at a high rate of evaporation, and especially when
the height between the inlet and outlet ends of the tubes is small compared with
the length of the tubes, the circulation of the water through the tubes may be
advantageously increased by employing one or more rotating fans or propellers
placed in the lower or other suitable part or parts of the boiler and driven by
means of a shaft or shafts extending through one or more stuffing boxes.
Dated this Seventeenth day of April 1894.
EDMUND HUNT,
Applicants' Agent.
Improvements in and connected with Water-tube Steam Boilers.
We, JAMES WEIR, GEORGE WEIR, and JOHN RITCHIE RICHMOND, all of
Holm Foundry, Cathcart, in the County of Renfrew, North Britain, Engineers,
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, that is to say :-
Our said invention relates to water-tube steam boilers of kinds in which steam
is generated in the tubes, and passes theuce to a steam space carrying water with
it, there being continuous circulation of water through the tubes; and our object
is to improve the action and increase the efficiency of such boilers, our invention
comprising automatic and other arrangements for preventing the tubes from being
injured through the expulsion of water from them which is liable to occur in
certain circumstances.

page_text: In boilers to which our improvements are applicable the tubes are subjected to
fire heat and constitute the principal heating surfaces, the water entering their
lower ends, passing through them in an upward or generally upward direction, and
being delivered along with steam from their upper ends into cylindrical or other
shells in which the steam space is contained. The water uot converted into steam.
passes down again to the lower ends of the tubes through one or more descending
passages or spaces. The water level may be above or below the upper ends of
the tubes.
From experiment and from comparison and consideration of data thereby
obtained we have learned that the rate of circulation through the tubes of a given
boiler with a given water level and with a given rate of evaporation per unit of
heating surface depends on the pressure of the steam. Thus, if with the maximum
pressure the circulation is such that the water in the upper parts of the tubes does.
not become so much diminished or mixed with so much steam that the tubes get
overheated and injured, but if, whilst other conditions remain the same, the steam
pressure becomes reduced (through a temporary increased consumption of it in the
engines or through other causes) then the steam as it is being formed in the tubes.
assumes a larger volume because of the diminished pressure, and in passing out of
the upper ends of the tubes has less water mixed with it, with the result that the
tubes become more or less overheated and injured.
By our invention we prevent injurious diminution of the pressure, and may
adopt various appliances and arrangements for that purpose, examples of such
appliances being hereinafter described with reference to explanatory drawings on
two sheets which are hereunto appended.
According to one modification the apparatus of which is shown in plan and in
vertical section in Figures, 1, and, 2, on Sheet, 1, of the drawings, we apply a
valve in the pipe or passage through which the steam passes on its way from the
boiler. This valve may be a simple plunger or piston working through a stuffing
box; but as generally it will be unnecessary for the plunger or piston part to be as.
large in area as the valve part, we show in Figure, 2, a comparatively small
plunger, A, working through a stuffing box, B, in the top of the valve casing, C,.
this plunger being made in one piece with a hollow cylinder, D, into which the
steam from the boiler has access through the inlet, E, of the casing. The
cylinder, D, is made with ports through its sides which ports, when the valve is
full open as shown in Figure, 2, coincide with ports, F, formed in a cylindrical
shell fixed in the casing, C, a space formed in the casing so as to encircle these
ports, F, leading the steam which passes through them to the outlet, G. The
plunger, A, is externally loaded, it might be by weights indicated by dotted
lines, H, but preferably by an adjustable spring acting directly or by a pair of
adjustable springs, H 1, acting on a crosshead, H 2, on the plunger. When the
steam pressure in the boiler gets below the predetermined amount the passage
becomes more or less closed by the action of the springs, H 1, or other load on the
cylindrical valve, D, the boiler pressure acting directly on the plunger, A, fixed to
the valve.
In a second modification as shown in Figure, 3, which is a vertical section the
valve, D, is of the double-beat kind the other parts being substantially the same as.
described for the first modification.
In a third modification shown in vertical section in Figure, 4, a large valve, J,
to close when the boiler pressure gets below the predetermined amount, is in the
form of an inverted cylindrical cup working on an inner fixed cylindrical piece, K,
which piece has formed centrally in it a small cylindrical chamber having working
in it a plunger, A, subject to the upward pressure of the boiler steam. The main
valve, J, has a tubular stem, J 1, passing upwards and out through a stuffing box, B,
and through this tubular stem, J1, but not filling it extends a rod, A. 1, fixed to the
plunger, A. A spring loaded lever, L, acting downwards on the plunger rod, A 1,
tends to keep the plunger, A, down, but when the boiler pressure is adequate it.
presses up the plunger, A, and opens the main valve, J, a flange, A 2, on the:

page_text: plunger rod then closing the bottom of the tubular stem, J 1. On the pressure
getting too low the plunger, A, descends and the flange, A 2, on its rod, uncovering
the bottom of the tubular stem J1, allows steam to escape through the stem from
the space, K 1, between the top of the main valve, J, and the inner fixed piece, K,
on which it works, in consequence of which the main valve closes. Steam gets into
the space, K 1, between the valve, J, and piece, K, which do not fit quite tightly.
Either along with or instead of valves such as are hereinbefore described for
controlling the main delivery of steam we may use a separate pipe connected with
an alarm or other apparatus. An example of such an arrangement is shown in
vertical section in Figure, 5, and comprises a whistle, M, the access of steam to
which is controlled by a valve, M 1, which boiler steam entering by the branch
pipe, M2, closes when of adequate pressure against the action of a spring, M 3,
this spring opening the valve on the boiler pressure getting below the predetermined
amount.
In water-tube boilers worked at a high rate of evaporation, and especially when
the height between the inlet and outlet ends of the tubes is small compared with
the length of the tubes, the circulation of the water through the tubes may be
advantageously increased by employing one or more rotating fans or propellers
placed in the lower or other suitable part or parts of the boiler, and driven by
means of a shaft or shafts extending through one or more stuffing boxes.
Figure, 6, on Sheet, 2, of the drawings is a vertical section showing portions of
upper and lower horizontal cylindrical boiler shells, N 1, N 2, connected by water
tubes, N, upon which tubes the furnace heat acts. The ends of the shells, N 1, N 2,
are connected by a large tube, P, for the descent of the water; and at the inlet
end of the lower shell, N 2, a centrifugal fan or propeller, Q, is arranged, being
fixed on a shaft, Q1, extending out through a stuffing box, and having on it a
pulley, Q2, for a driving belt.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
:-
1. In a water-tube boiler arranging a valve which by the action of one or more
springs or weights more or less closes the passage for the boiler steam when its
pressure gets lower than a predetermined amount substantially as and for the
purposes herein before described.
2. The construction of valve substantially as and for the purposes hereinbefore
described with reference to Figures, 1, and 2, of the accompanying drawings.
3. The construction of valve substantially as and for the purposes hereinbefore
described with reference to Figure, 3, of the accompanying drawings.
4. The construction of valve substantially as and for the purposes hereinbefore
described with reference to Figure, 4, of the accompanying drawings.
5. In a water-tube boiler arranging alarm apparatus to be actuated by the boiler
steam when its pressure gets lower than a predetermined amount substantially as
and for the purposes hereinbefore described.
6. The construction of valve substantially as and for the purposes hereinbefore
described with reference to Figure, 5, of the accompanying drawings.
7. In a water-tube boiler arranging one or more fans or propellers to increase
the circulation substantially as herein before described.
Dated this Fifteenth day of January 1895.
EDMUND HUNT,
Applicants' Agent.