Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1~)48787
Apparatus and a process for the production of mineral fiber are
disclosed in a U.S. patent to Downey 2,646,593. In the process disclosed a
gravity-type collecting chamber is utilized to collect the fiber subsequent
to its formation. With the advent of the energy crisis application of
mineral fibers as thermal insulation to domestic, commercial and industrial
structures has become increasingly important and widespread. In applying
thermal insulation to existing structures, the primary and most effective
form of application is by blowing-in the fiber using specialized equipment.
Such specialized equipment is sensitive to the presence of unfiberized
particles or "shot" in the material moving through it. The maintenance cost
is decreased and the service life appreciably lengthened for such equipment
by a refining of the fiberized material so that the presence of shot is
minimized or eliminated.
The method and apparatus of the present invention provide improved
separation of shot from the fiberized material prior to its final accumulat-
ing. The conventional, large collecting chamber is eliminated as are other
moving components customarily utilized such as conveyor screen, rotary screen
cleaning system and the granulator or hammermill often necessary to reduce
the product to the desired consistency. The product resulting from the
method and apparatus of the present invention is characterized by the absence
of unfiberized material and is particularly adapted for application by blow-
in apparatus.
According to a first broad aspect of the present invention, there
is provided a method of producing a homogeneous mineral fiber product from a
stream of molten slag comprising: rectilinearly projecting and fiberizing
the slag by entraining it in an annularly arranged array of steam jets;
providing a collecting tube concentric with the annular array of steam jets
for receiving the fiberized material with the open receiving end of the tube
spaced from the point of entry of the slag into the steam flow and having a
diameter somewhat less than that of the remainder of the tube to provide a
conical entry section; connecting the end of said collecting tube remote
from the entry section to an initial cyclone-type centrifugal separator;
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dropping the product issuing from the lower end of the cyclone separator
through an unloading valve; drawing off the fiberized material of lesser
mass through a horizontal tube communicating with the discharge from the
unloading valve; providing a conveying tube communicating with the horizon-
tal tube and with the intake of a second cyclone-type centrifugal separator;
providing air moving fans for establishing suction in said collecting tube,
horizontal tube, conveying tube and said centrifugal separators; and provid-
ing a means for accumulating the homogeneous product issuing through an un-
loading valve from the lower end of the second centrifugal separator.
According to another broad aspect of the invention, there is pro-
vided an apparatus for producing a homogeneous mineral fiber product from a
stream of molten slag comprising: means for fiberizing the slag by entrain-
ing the slag stream in an annularly configurated horizontal steam jet, a
collecting tube having its open end spaced from the point of entry of the
slag into the steam jet and concentrically aligned therewith for receiving
the fiberized material, said receiving end of the collecting tube having a
diameter somewhat less than that of the remainder thereof to provide a
horizontal conical entry section, said collecting tube having an upwardly -
inclined portion and a terminal horizontal portion, an initial cyclone-type
centrifugal separator having its intake connected to the end of said
horizontal portion of said collecting tube remote from said entry section,
means for reducing the pressure in said collecting tube and separator to
sub-atmospheric, an unloading valve receiving the discharge of the separator,
a conveying tube having a horizontal portion communicating with the vertical-
ly falling discharge from said unloading valve and having an upwardly inclined
portion terminating in a horizontal portion, a second cyclone-type centrifugal
separator having its intake communicating with the horizontal portion ofsaid
conveying tube, means for reducing the pressure in said conveying tube and
said second separator below atmospheric an unloading valve receiving the
discharge of said second separator and means for accumulating the material
discharged through the unloading valve from said second separator.
The invention will now be described in greater detail with refer-
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1048787
ence to the accompanying drawings in which:
Fig. 1 is a schematic view of the interconnected apparatus utilized
to practice the method of the present invention;
Fig. 2 is a side sectional view of a portion of the structure
shown in Fig. 1 and illustrating the positional relation of the components
shown;
Fig. 3 is a schematic side sectional view of the dry centrifugal,
or cyclone, type of separator shown in Fig. l; and
Fig. 4 is a schematic, side sectional view of the rotary valve
component shown in Fig. 1.
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787
Referring initially to Fig. 1, a conventional means for producing
a stream of molten slag material is indicated generally at 10 and,
as is shown particularly in Fig. 2, this apparatus may include a
spout or chute 11 down which a stream of molten slag 12 progresses.
The molten slag may be tapped from a cupola (not shown) as is con-
ventional. The molten slag falls from the end of the chute onto the
inner marginal area of a generally cup-shaped spinner 13 which is
rotated by a shaft 14, the shaft being rotated by a power means
indicated generally at 16 in Fig. 1. It will be understood that,
as is conventional in forming mineral fiber, rotation of the spinner
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~-~ 13 will cause finn~ly divided streams of molten slag to move
tangentially outwardly from the periphery of the spinner.
The tangentially moving streams of slag are projected horizontally
and fiberized by means of an annular array of steam jets 16, the high
- velocity steam issuing from the jets, indicated at 16a in Fig. 2,
intersects the outwardly moving streams of slag and projects them
horizontally rightwardly as viewed in Fig. 2. The annular array of
steam jets 16 are disposed in an annular steam header 17 which is
supplied by the pipe 18.
The horizontally projected, fiberized material is received in a
collecting tube indicated generally at 21 in Fig. 1 and composed of
an inclined portion 21a, a horizontal portion 21b and an open
receiving end 21c. The open receiving end 21c of the collecting tube
21 is spaced ~rom the point of entry of the slag ~treams into the
steam flow and the magnitude of this spacing is indicated at A in
Fig. 2. The diameter of the open end 21c of the collecting tube
is indicated at B in Fig. 2. The diameter of the end 21c of the tube
is somewhat smaller than the diameter of the tube at a point spaced
rightwardly from the end 21c so that the horizontal portion 21b of the
tube has a slight conical configuration. In a preferred form of the
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apparatus the dimension A is approximately 2~ inches and the diameter
B is 22 inches, the remaining portion of the tube 21 being of a uni~orm
24 inches in diameter. Small variation ~rom these dimensions are
possible without losing the advantage o~ the system, however, the
dimensions set out appear to produce optimum results. The inclined
portion of the tube 21 is preferably arranged at an angle o~
approximately 40 from the horizontal.
The upper portion o~ the tube 21 is provided with a horizontal
portion 21d which communicates with the interior o~ an initial cyclone-
type centri~ugal separator indicated generally at 31 and shown in detailin Fig. 3. As may be seen in Fig. 3, the entry portion 21d o~ the tube
21 is flattened in con~iguration somewhat so that air and entrained
material moving through the tube are fed in a radially thin sheet
tangentially into the separator.
The separator 31 is of conventional construction and this type
o~ separator is commonly re~erred to as a "cyclone". Referring
particularly to Fig. 3, the separator has a lower, cone shaped body
31a communicating with a lower discharge tube 31b. Extending from
the upper end of the cyclone 31 is a tubular discharge duct 31c
which extends a distance into the body o~ the cyclone. Various
forms of air moving means may be utilized for drawing air through
the cyclone and, as here shown, takes the form o~ the vane axial
fan 32 driven by the motor 33.
Re~erring to Fig. 3, as air with entrained ~iberized material is
drawn into the cyclone through the tube 21d by the ~an 32, two
distinct vortices are established in the cyclone. One is a large-
diameter vortex descending helically down the cone shaped body
portion o~ the cyclone and identified at 34. The other, identified
at 34a, is an ascending helix of smaller diameter which extends upward
~rom the region o~ the outlet tube 31b, through the inner cylinder
provided by the inwardly extending end o~ the tube 31c and through
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104~3787
tube 31c to atmosphere. The air and entrained material, moving in
the outer vortex path 34, separates at the base o~ the cyclone and
the air from the outer vortical stream joins the rising inner vortex
~low of air. In its passage from the lnlet 21d to the apex of the
cone, the entrained, fiberized material remains close to the outer
wall, because of centrifugal ~orce, and passes out the outlet tube
31b with a minimum of re-entrainment o~ the flberized material into
the upper vortex. The operation of the cyclone 31, as described above,
is conventional and the cyclone functions to concentrate the fiberized
material and drop it through the lower discharge duct 31b.
Referring to Figs. 1 and 4, a rotary unloadlng valve is disposed
in the tube or discharge duct 31b, the valve being shown in schematic
detail in Fig. 4 and identi~ied generally at 41. The use of the valve
is necessary because the discharge duct 31b operates at negative
pressure and must be sealed so that air cannot enter through the tube
31b. If air in any quantity were permitted to enter tube 31b~ the
suction at the inlet tube 21d would be destroyed, and the admission
of air through the discharge duct 31b would further seriously interfere
with the vortical separation necessary for the operation of the cyclone.
An independently rotated shaft 41a rotates a series of radial vanes
41b in counterclockwise direction as viewed in Fig. 4, these vanes
serving to accumulate the ~iberized material, indicated at 51 and
drop it through the discharge 41c of the rotary valve.
As indicated in Fig. 1, just below the rotary valve 41, a
horizontal tube 52 communicates with the interior of the discharge
tube from the rotary valve. The horizontal tube 52 communicates
with the upwardly inclined portion o~ a conveying tube 53. The
conveying tube 53 communicates with a horizontal portion 54 which
enters a second cyclone-type centrifugal separator indicated generally
at 56. The cyclone separator 56 is substantially identical to the
87
cyclone 31 previously described with rei'erence to Fig. 3 and the tube
54 enters the cyclone at its periphery in the same fashion as the tube
21d enters the cyclone 31. The cyclone 56 includes a power driven
fan (not shown) at its upper discharge 56a and this fan ~erves to
lower the pressure within the tube 52, tube 53 and tube 54 ~o that
material moving past the open end of the tube 52 is drawn into the
collector tube 53. The cyclone 56 is characterized, as was the case
with cyclone 31, by the formation in its interior o~ two concentric,
helical flow paths for air, with entrained material moving out o~
the cyclone through its lower discharge passage 56b. The unloading o~
the cyclone 56 must, o~ course, be accomplished through an unloading
valve~which prevents entry of air back up into the cyclone through
the passage 56b. The fiberized material moving downwardly through
the passage 56b is directed into the throw-out cone 57 which
communicates through the tube 58 with a conventional bagger apparatus
59.
In operation, molten slag is directed onto the rotating spinner
13 and is centrifuged tangentially outwardly from the periphery o$
the spinner. The steam blast from the jets 16 strips the attenuated
slag from the spinner and fiberizes it, projecting the fibers into
the open end 21c of the slightly conical horizontal tube 21b which
is aligned concentrically with the rotational axis of the spinner.
~he heavier shot, or unfiberized slag, tends to fall outwardly of
the perimeter oi' the tube end 21c and the fibers and only a minimum
of shot enters the tube 21.
The sub-atmospheric pressure maintained in tube 21 by the fan 32
~ig. 3) causes the fiber to travel up the inclined tube 21. This
cools the fiberized material and prevents matting together of the
fibers. In passing through the primary cyclone 31 the fiber is
collected and concentrated. The material is dropped from the rotary
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valve 41 and across the mouth o~ the horizontal, air pick-up tube 52.
This permits the tube 52 (the interior of which is under sub-atmospheric
pressure because of the operation of the ~an incorporated in the
secondary cyclone 56) to draw in the lighter fibers while the heavy,
unfiberized shot and slugs fall past the tube 52 and out of the system.
The method results in an unmatted, consistent, fiberized product
characterized by minimum presence in it of shot or unfiberized slugs.
No large collecting or settling chamber is necessary. ConveYor
screens, rotary screen cleaning apparatus and granulator apparatus,
conventionally utilized, are unnecessary. Because a suction type
conveying system is used, leaks are inward and little or no dust
or fiber can migrate to the exterior surrounding area. The spaclng
of the open end of the conical, horizontal tube 21b from the point
of entry of the molten slag into the steam flow is such as to
cause the heavier shot to move to the outside of tube 21b, without
entering the tube, and these heavier particles, inherently formed in
the fiberizing process, are thus excluded from the system early in
its progress.
