appar
Year: 1888

page_text: 1, EDWARD WALSH, Jr., of 417 Olive Street in the City of St. Louis, State of
Missouri, United States of America, Glass Manufacturer, do hereby declare the
nature of my invention and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement
O
My invention relates to important improvements in the internal form and arrange-
ment of blast furnaces and in charging apparatus therefor, and is particularly
applicable to that class of furnace for which letters-patent of Great Britain were
granted to me October 18, 1886, No. 13,266 for improvements in Blast Furnaces, in
which the bosh is located well down within the zone of fusion.
My invention has for its object to maintain the initial pressure of the blast as it
enters the zone in the immediate vicinity of the tuyeres, throughout the entire furnace
whereby the velocity, pressure, and density of the gases on the materials to be treated
will be rendered uniform at every part of the furnace and therefore under the control
of the operator-an advantage hitherto unattainable.
Also to ensure a constant charge of materials to the furnace at the stock line, to
effect the raising of the bell in a direct vertical line by compressed air from the blowing
engines, or other motive fluid instead of by levers and chains, and to notify the
operator when a fresh supply of materials is required above the stock line for charging
the furnace.
In a blast furnace, which may be said to comprise generally a cylinder for hearth,
an inverted truncated cone for bosh, and a truncated cone for shaft, the highest
temperature produced by the intense incandescence of the fuel in active combustion is
in the immediate neighborhood of the tuyeres-notwithstanding, in consequence of the
refrigerating influence of the entering air which is in a comparatively cool state, this
high temperature is not immediately imparted to the gases generated from the air thus
entering, and they are not therefore expanded to their fullest extent in this region.
Repeated observations on the practical working of blast furnaces have demonstrated
that the gases are not fully expanded until they reach the upper limit of the fusion
zone, as is plainly evident on examination of sections of furnaces that have been in use
for some time. In such furnaces it will be found that a relation exists between the
hearth area and the area of the top of the fusion limit and that an invariable ratio is

page_text: maintained between these two areas. Thus the temperature for fusing cast iron is
about 2400 degrees Fah. whereas at the upper limit of the fusion zone the temperature
required for producing a chemical combination and fusing of the silicates which
compose the slag, is in excess of 3000 degrees Fah.
Now by applying the well known formula for the expansion of gases at these two
temperatures it will be seen that there is a fixed cause or law for the ratio between
these two areas, the gases being expanded three-fold by this increase of temperature.
This accounts scientifically for the constant relation that is always found to exist
between the area at the upper limit of the fusion zone and that of the hearth in worn
sections of furnaces; for in the case of a furnace originally made larger than that
determined by the above formula at the upper limit of the fusion zone it is found that
scars of slag or fine carbonaceous matter are deposited on the sides of the furnace until
the above relation between the areas is reached, and on the other hand in case of a
furnace made smaller at the limit named it is found that the brickwork notwithstanding
any artificial means adopted for cooling it will be worn away until the said relation is
established.
As a rule the temperature of the gases issuing from the furnace at the throat or
tunnel head is between 400 and 1000 degrees Fah. and by applying the above formula
to this decreased temperature (relatively to that required to make the slag) it will be
seen that the area of the throat or tunnel head should be between and the area at
the upper limit of the bosh or 'fusion zone.
By preserving the above constant ratios of areas according to the temperature
required and obtained at any zone on horizontal plane of the furnace the proper
sectional form and combined disposition of the internal parts of the furnace are
accurately determined with the result that when the furnace is in operation the initial
pressure imparted by the blowing engine to the zone in the immediate vicinity of the
tuyeres is maintained throughout the entire furnace and that, consequently, the
velocity, density and impingment of the gases on the materials to be treated are
rendered uniform at every part of the furnace and are entirely under the control of
the operator which is not the case with the furnace in present use wherein the zones
have been so indifferently proportioned to the requirements of the process that owing
to the varying pressure of the blast and gases within the furnace only irregular and
more or less wasteful and imperfect results are obtained.
Now my invention consists in forming the interior of a blast furnace according to
the above defined principle as discovered by me in connection with the subject, or so
that the sectional areas of the hearth, upper limit of bosh or fusion zone, throat or
tunnel head, or any intermediate zone of the furnace, will have constant relations to
each other according to the volume of the gases as found by applying the well known
formula for the expansion of gases to the temperature required and obtained at each of
the said parts, or at any zone of the furnace as the case may be.
Figure 1 on the accompanying drawings represents a vertical section of my improved
blast furnace having the furnace proper A, furnace shaft B, bosh C (which is brought
down well within the zone of fusion as described in my said previous letters patent)
and the hearth cylinder G.
I make the sectional area of the furnace at the upper limit 1-1 of the bosh or fusion
zone C three times (or thereabouts) the area at the hearth G and about five to seven
times the area of the throat or tunnel at 2-2, these being the fixed proportions given
for these parts respectively by the application of the above formula to the various
temperatures thereat. From the upper limit 1-1 of the bosh the walls of the
furnace curve or slope gradually downwards and inwards to the top of the hearth
cylinder G and upwards and inwards to the throat or tunnel head 2-2.
This proportion of parts, as far as diameters are concerned, is necessarily fixed;
but in order to ensure the fullest economy in the use of various kinds of ores it will
be found that the height of the furnace should be made to vary with the character of
the ore, that is to say: A non-refractory and easily smelted ore will not require
for its treatment as great height of furnace as a dense refractory ore difficult of
treatment.

page_text: By my invention a stronger impingement of gases at greater density and velocity
is obtained and the materials in preparation in the upper portions of the furnace are
more thoroughly prepared and therefore a minimum amount of fuel is required for
the reduction and smelting of the iron ores, all the space within the furnace is utilized,
the process is under control of the operator and a uniformity of results is secured,
unobtainable by the most approved constructions of the day.
For ensuring the proper charging of the furnace A arranged as described I use a
special charging apparatus which consists in a combined hopper and magazine or
chamber arranged vertically above the stock line of the furnace for containing a
series of charges of the materials which are supplied from an upper box or hopper
inserted within the mouth of the magazine or chamber, the opening into the latter
from the supply box or hopper being opened or closed as required by the bell which
is counterbalanced by weights and carried centrally by a rod extending upwards through
a hollow piston rod to which it is adjustably secured by keys. The hollow piston
rod is attached to a piston fitted in a cylinder to which the motive fluid is admitted,
the whole being supported above the furnace by columns and girders, and operated so
that on admitting the motive fluid to the cylinder above the piston the bell is thereby
lowered and opens the supply box or hopper so as to allow the materials to pass
therefrom into the magazine or chamber, and on admitting the motive fluid below
the piston the bell is thereby raised and closes the supply box or hopper so as to
prevent the escape of gases from the contents of the magazine or chamber.
During the descent or charging of the materials from the magazine or chamber into
the furnace at the stock line the pressure thereby induced depresses a lever having an
armature which is thereby held out of contact with an adjacent electric battery, but on
the sinking of the materials below the lever the latter becomes free and its armature
being attracted to the magnet closes the circuit and causes a bell or gong to be sounded
as a signal to the operator that a fresh supply of materials is required. When it is
required to raise the bell for removal from the apparatus it is first lifted vertically for
a distance corresponding with the stroke of the piston when the keys by which the
rod carrying the bell is secured to the hollow piston rod are removed and the piston
being lowered the keys are again inserted into corresponding lower key-ways in the
bell rod and a second lift made, until the bell is sufficiently high to be moved to one
side clear of the supply box or hopper.
Figure 2 of the drawings represents a sectional elevation of my improved charging
apparatus applied to the furnace above the stock line, partly broken away; Figure 3
a plan thereof, and Figure 4 a detached longitudinal sectional view through the
cylinder and piston rod seen in Figure 2, to an enlarged scale; like letters of reference
denoting like parts in all the figures.
a represents the hopper through which the materials are charged into the furnace
through the shaft B at the stock line. Combined and in vertical line with the hopper a
is a conical or cylindrical magazine or chamber c of sufficient capacity to contain a
supply of several charges of the materials to the furnace. Within the upper open end
or mouth of the magazine or chamber c is inserted a hopper framed of suitable depth
and flanged internally at its lower end for supporting a conical shaped annular ring or
collar e having a central supply opening which is closed or opened circumferentially to
the magazine or chamber c by the bell which projects centrally upwards into the box
or hopper de as hereafter more particularly described.
To the top of the bell fare secured chains g which pass upwards over pulleys h and
carry at their other ends weights i for counterbalancing the bell f.
To the top of the bell is centrally attached the lower end of a rod j which extends
vertically upwards through a hollow piston rod k fixed to a piston (seen more
particularly in figure 4) which is capable of reciprocation within the cylinder m. The
suspension rod of the bell is normally secured to the piston rod k by keys n, the
key-ways
n' for which are formed in the rod j at distances apart corresponding with
the stroke of the piston l.
The motive fluid is admitted to the cylinder m above or below the piston / as required
by means of a three-way cock o worked by a pulley p and endless rope q from any

page_text: convenient position adjacent to the furnace, or the admission of motive fluid to the
cylinder m may be regulated in any other suitable manner as found most convenient.
For carrying the entire apparatus the upper end of the magazine or chamber c is
supported by the ring casting r carried by the columns s which rest on the top of the
furnace shaft B.
On the ring are uprights t connected together at the top by girders u which
support the bearings of the pulleys h, counterbalance weights ? and cylinder m with
its appendages. Beneath the girders u are rollers v for guiding the suspension rod j
of the bell f.
For charging the furnace the motive fluid is admitted to the cylinder m above the
piston 1, which is thereby forced to the bottom of the cylinder m and lowers the bell f
so as to unclose the supply opening through the bottom of the box or hopper de and
open communication between the latter and the magazine or chamber c. The materials
are then dumped in regular charges through the box or hopper de into the furnace and
magazine or chamber c until the latter is filled to the desired level when the motive
fluid is exhausted from above, and admitted below the piston 7, which is thereby forced
to the top of the cylinder m and raises the bell f so as to close the supply opening in
the bottom of the box or hopper de and thereby prevent the subsequent escape of the
gases of combustion from the magazine or chamber c.
In the wall of the magazine or chamber c somewhat above the stock line adjacent
to the hopper a is pivoted a lever w of the first kind, the outer arm.of which, external
to the magazine or chamber c is provided with an armature a, whilst its other arm is
directed downwards and pressed upon by the materials within the magazine or
chamber c so as to normally hold the lever w with its armature out of contact with
an adjacent electro magnet y.
When the materials in the magazine or chamber c have fallen during the operation
of the furnace below the level of the inner arm of the lever w the latter becomes free
and its armature x being attracted to the magnet y a bell is thereby sounded which
notifies the operator that a fresh supply of materials is required in the magazine or
chamber c this being effected by repeating the operation above described.
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: A blast furnace in which the sectional area of the upper limit of its bosh is
substantially three times its hearth area and substantially five to seven times the area
of its tunnel head, substantially as shown and for the purposes specified.
2: In an apparatus for charging blast furnaces, the combination of a hopper
discharging into the furnace shaft from a magazine or chamber having an upper
supply box or hopper, a bell counterbalanced by weights and secured by a rod to a
hollow piston rod carried by a piston in a cylinder and operated by compressed air or
other motive fluid, the whole being supported by suitable framing and operating
substantially as described and for the purposes specified.
3 The combination of the bell counterbalanced by weights, a rod attached to said
bell and having key ways and openings, a hollow piston rod carried by a piston fitted
in a cylinder, said piston rod having keys, the whole operating to raise the bell for
removal, substantially as described.
4: The combination of lever w having armature x and projecting within the
magazine or chamber c, with electro magnet y, substantially as described.
Date : 4th dow of Tuno 1000