Improvements in Valves for Hot Blast Stoves and Furnaces.
Year: 1892

page_text: Date of Application. 12th Apr., 1892-Accepted, 28th May,
1892
COMPLETE SPECIFICATION.
[Communicated from abroad by HUGH KENNEDY, Sharpsburg, Pennsylvania,
United States of America.]
Improvements in Valves for Hot Blast Stoves and Furnaces.
I JAMES JOHNSON of 4 Clayton Square Liverpool in the County of Lancaster,
Patent Agent 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 :-
Figure 1 is a vertical section of the upper portion of a hot blast stove, having my
improved valve attached and showing the valve closed.
Figure 2 is a view of the same showing the valve open.
Figure 3 is a plan view of the stove, and the valve in the same position as in
Figure 1.
Figure 4, is also a plan view of the stove showing the valve in the same position
as at Figure 2; and
Figure 5 is a sectional view taken on the line X-X of Figure 3.
My invention relates to the improvement of outlet valves for hot blast stoves,
such as are shown in the Specification to British Letters Patent No. 3817 of the
year 1889, and granted to John Thomson King as a communication and the object
of my present improvement is to provide an outlet valve for this class of hot-blast
stoves, which shall be simple in construction, effective in action, and have little
liability to get out of repair. Heretofore the valves controlling the outlet to hot
blast stoves have been operated by the use of an arm or rod, running through a
stuffing box or other packing arrangement, which arrangement has not given good
satisfaction. The position of the valve makes it very difficult to make the outlet
gas-tight or air-tight, without causing considerable extra friction, which makes the
valve hard to control and instead of moving easily and smoothly, and seating firmly
in place when required, the valve plate keeps tightening and binding, causing more
or less difficulty of operation; and as more or less of the blast would force its way
out in spite of the attempted packing or stuffing, a disagreeable whistling noise was
kept up more or less of the time.
By the use of a valve constructed and applied as herein described and pointed
out, the need of a stuffing box, or of any packing material, is entirely dispensed
with, and the operator is enabled to control the outlet of the stove and the action of
the valve with ease and accuracy. To enable others to understand my invention, I
will proceed to describe it in detail.
A, is a hot-blast stove of the usual construction, as heretofore referred to; the
gas outlet of which is shown at o; this outlet is governed or controlled by the
valve B, which consists of the sliding-plate b, which moves laterally in the recess
between the parallel plates c and d which form a casing for it extending around the
side edges and ends of the sliding plate so as to form an enclosing box or casing
therefor, and being of sufficient length to permit the sliding-plate to be moved so as
to uncover the outlet o over which it is set. This casing formed by the plates c
and d does not fit tightly against the valve-plate 6 but instead a sufficient space for
clearance is allowed as indicated at e to permit of a slight vertical play to the
plate b.
Longitudinal movement is given to the plate 6 by means of the rack arm f, which
is pivotally secured to the surface of the plate b, at g, and geared with the spu.
wheel, on the shaft i which is operated in the usual manner. In the construction
of the valve, the lower face of the upper plate c,, and the upper face of the valve-
plate 6, are planed smoothly so as to admit the valve plate 6 being closely seated
against the lower face of the casing c when the valve is closed.

page_text: The several views of the drawing only represent one of a series of stoves such
are shown and described in Letters Patent No. 3817 of the year 1889 herein before
referred to; and the port a is for the admission of air from the other stoves of the
series. The arrow shown within the casing or stove, in Figure 5, indicates the
course taken by the gas, which enters the stove at its lower end, and then flows
upwardly through the gas outlet, while the arrow upon the outside of the stove, at
the port a, indicates the course taken by the air, which after entering the stove
flows downwardly, as fully described in my former Letters Patent.
is
The mode of operation of the valve will be as follows:-When it is desired to
put the stove in operation, the outlet o is closed by sliding the valve plate b in
position as shown in Fig. 1. The pressure of the blast when turned on will then
raise the plate 6 and press it firmly against the lower face of the upper portion of
the valve casing shown at c and cause it to seat itself there. So long as the blast
on, the valve-plate will be held in position, and the stronger the blast, the tighter
and closer will the valve-plate be seated. When the blast is turned off, the valve
plate will drop by its own weight away from the casing c, the distance allowed for
clearance in the space e, and then by the proper manipulation of the spur-wheel, it
will slide back easily into the recess prepared for it, between the plates c and d.
The opening of the valve is of an oblong shape preferably as shown in Figures 3
and 4, and of sufficient length to admit of the valve plate sliding back far enough
to clear the outlet o, without being stopped by the lug g, to which the rack arm fis
attached striking the top plate or casing c.
When the valve plate b is closed as shown in Figure 1, and forced up against its
seat by the internal pressure in the stove, the enclosing casing formed by the plates c
and d constitutes a closed box which entirely prevents the escape of air, and as no
stuffing boxes are required to be used as in prior outwardly-seating-valves of this
class, the valve is not apt to get out of order or to leak. The saving of waste of
air, the saving of labor in manipulation and keeping in repair of the valve, which I
thus effect, are very considerable, and render my valve and improvement over prior
constructions. These features of advantage are of special importance where the
valve is applied to the top of a hot-blast stove, where from its difficultly accessible
position, leaking of the air is apt to remain unnoticed by the workman who operates
it from the base of the stove, while defects in its working are often productive of
serious inconvenience. It will be understood that the valve is capable of use not
only on hot blast stoves, but in other types of furnace in which an opening is to be
closed to prevent escape of gas or air from within.
This mode of construction may be applied to a series of hot-blast stoves, by
arranging the shafting so as to operate the valves simultaneously, if so desired..
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 :-
First. A valve for hot blast stoves and other furnaces, consisting in the combina-
tion with an outwardly-seating sliding valve-plate, of a casing in which it is longi-
tudinally movable, said casing having an opening adapted to register with the
furnace port to be controlled and enclosing the valve plate at its side and end
edges and at the margins of its surface, and operating mechanism connected with
the outer exposed surface of the valve plate and adapted to slide the same;
substantially as and for the purposes described.
Second. A valve for hot blast stoves and other furnaces consisting in the com-
bination with an outwardly-seating sliding-valve-plate, of a casing in which it is
longitudinally movable, said casing consisting of parallel plates having registering
openings, against the upper one of which plates the valve-plate is seated by pressure
on its inner surface, said plates enclosing the valve-plate at its side and end edges
and at the margins of its surface, and operating mechanism connected with the
outer exposed surface of the valve plate and adapted to slide the same; substan
tially as and for the purposes described.

page_text: Third. A valve for hot blast stoves and other furnaces, consisting in the com-
bination with an outwardly-seating sliding valve-plate, of a casing in which it is
longitudinally movable, said casing having an opening adapted to register with the
furnace port to be controlled and enclosing the valve-plate at its side and end edges
and at the margins of its surface, a rack-arm pivotally connected to the exposed
surface of the valve-plate, and a pinion in gear with the rack-arm and adapted to
operate the same; substantially as and for the purposes described.
Deted the 11th dow of Anril 1809
J. JOHNSON.