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Publication numberUS3731910 A
Publication typeGrant
Publication dateMay 8, 1973
Filing dateMay 17, 1971
Priority dateMay 17, 1971
Publication numberUS 3731910 A, US 3731910A, US-A-3731910, US3731910 A, US3731910A
InventorsButler T
Original AssigneeButler T
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Cupola structure
US 3731910 A
Abstract
Mounted adjacent the closed top of a cupola stack is a hopper which rains a torrent of discrete heat-exchange particles such as sand downwardly through the upward flowing hot gases in the stack. Deflectors within the stack deflect the torrent toward a discharge opening in the side of the stack above the melt zone. Accumulated particles adjacent the discharge opening seal the gases against escape therethrough. An outlet from an expansion chamber adjacent the top of the stack passes the cooled gases to a conventional filter which removes the smoke burden from the gases.
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Description  (OCR text may contain errors)

0 United States Patent [191 [in 3,731,910

Butler May 8, 1973 [54] CUPOLA STRUCTURE [76] Inventor: Thomas J. Butler, 7625 E. Morrow Primary Ca mby Circle Dearbom, Mich 48126 Attorney-Barnes, Kisselle, Raisch & Choate [22] Filed: May 17, 1971 ABSTRACT [21] Appl' 144,024 Mounted adjacent the closed top of a cupola stack is a V hopper which rains a torrent of discrete heat-exchange [52] US. Cl. 266/15, 266/31, 55/262, 55/267, 432/67 particles such as sand downwardly through the upward [51] Int. Cl ..F27b 1/18 flowing hot gases in the stack. Deflectors within the [58] Field of Search ..263/29, 50; 266/15, stack deflect the torrent toward a discharge opening in 266/17 the side of the stack above the melt zone. Accumulated particles adjacent the discharge opening seal the References Cited gases against escape therethrough. An outlet from an expansion chamber adjacent the top of the stack UNITED STATES PATENTS passes the cooled gases to a conventional filter which 3,645,515 2/1972 Kemmetmueller ..263/32 removes the smoke burden from the gases. 1,884,088 l0/l932 Miller ....266/l7 X 3,507,482 4/1970 Kraszewski et a1. ..263/32 R 17 Claims, 3 Drawing Figures PATENTEDIW 81915 3,731,910

' INVENTOR. THOMAS J. BUTLER ATTOPNEYC;

CUPOLA STRUCTURE This invention relates to a cupola for producing molten metal such as iron. More particularly, the invention involves an improvement of the cupola structure which facilitates cooling the gases therein to such an extent that the gases can be passed directly from the cupola stack to a conventional filter for removing the smoke burden without damage to the filter.

Gases issue from a typical cupola at about 2,000 F. at a rate of many thousands of cubic feet per minute and are heavily laden with smoke. By smoke is meant particulate, unburned products of combustion such as coal or coke fines, ash, metal oxide fines, and the like. Because of this combination of high heat, high volume, and heavy smoke burden, no apparatus or system devised before the present invention has been capable on a reasonably economical basis of effectively removing the smoke from gases issuing from a cupola.

A particularly knotty problem is that gases issuing from a cupola are so hot that they cannot be handled by conventional filters. A conventional approach to this problem has been to subject the gases to a spray or stream of cooling and cleansing water. This approach has been unsatisfactory because it generates steam which increases the volume of the gases and compounds the difficulty of their handling; the water leaves a residue of smoke burden which must be removed by other means; the water does not cool the gases sufficiently for handling by conventional filtering devices; and water-cooling systems are very expensive to build, operate, and maintain. Typically, the initial cost of such a system ranges from about $200,000 to about $600,000, its water consumption and power requirements are very high, and continual maintenance is required.

The object of the present invention is to provide a cupola structure improved so that the smoke-laden gases can be cooled within the cupola stack itself to such an extent that the gases issue from the stack at a temperature and volume within the handling capabilities of conventional filtering or collecting equipment, the structure being relatively simple to build, operate and maintain so that it is economically available for use by industrial concerns of moderate financial means.

In general, the invention is carried out by closing the upper end of the stack and providing adjacent its upper end a hopper which rains a torrent of discrete, heat-absorptive particles such as sand or metal shot downwardly through the stack. The upwardly flowing gases are cooled by the particles and arrive at the top of the stack at about 200 F. and commcnsurately diminished volume. The gases in this condition can be filtered by conventional filtering or collecting devices. Deflectors are provided within the stack to deflect the torrent of particles toward a discharge opening in a side portion of the stack above the melt zone. The deflectors shield the melt zone from penetration by significant quantities of the heat-absorptive particles.

One form of the invention is illustrated in the accompanying drawings.

FIG. 1 is a partly diagrammatic representation of a cupola embodying the present invention.

FIG. 2 is an enlarged fragmentary diagrammatic view of an apertured hopper bottom and gate plate associated therewith.

FIG. 3 is a generally elevational view in the direction of arrow 3 of FIG. 1, parts being broken away and shown in phantom to illustrate structural details.

Shown in FIG. 1 is a cupola 10 according to the present invention having a charge door 12 through which a charge is introduced into melt zone 13 by such means as a charger 14. Typically, where the cupola is used in producing molten iron, the charge includes coke, iron, or steel, and slag-producing material such as limestone. Combustion air is introduced into the cupola by means ofa manifold 16 and tuyers 18. The molten metal is drawn off by a trough or launder 20. As is conventional, cupola 10 has a stack 22 which extends upwardly of charge door 14.

In accordance with the invention, the upper end portion 24 of stack 22 has an enlarged diameter to define an expansion chamber 26. The top of the expansion chamber is closed by a closure 28. A hopper or container 30 is mounted adjacent the upper end of the stack; and in the structure illustrated, hopper 30 is suspended from closure 28 within expansion chamber 26.

A chute 32 communicates into the interior of hopper 30 through an opening 34. A mass 36 of heat-absorptive particles is introduced into hopper 30 through chute 32 and opening 34. The mass of particles rests upon and substantially covers the bottom 38 of the hopper (FIG. 2). Bottom 38 is provided preferably throughout its area with a number of downward openings 40.

Beneath hopper bottom 38 is a gate plate 42 which is movably mounted so that a number of openings 44 therein can be shifted to and from registry with openings 40. Gate 42 is moved by suitable means such as a control arm 46 (FIG. 1). Openings 40, 44 are preferably distributed over a major portion of the diameter of stack 22. When openings 40 and 44 are in partial or full registry, a number of streams of particles from mass 36 rain in a free-falling torrent downwardly through stack 22, the volume of which is adjustable by moving gate 42.

Mounted within stack 22 are an upper deflector 48 and a lower deflector 50 both of which are sloped to deflect the rain of heat-absorptive particles toward a discharge opening 52 in a side portion of stack 22 above melt zone 13. Lower deflector 50 has curved edge portions 54 secured to the stack interior so that the lower deflector and adjacent portions of the stack interior define a receptacle 56 within which the heatabsorptive particles accumulate for discharge through opening 52.

Upper deflector 48 has edge portions 58 secured to interior portions of stack 22 which are generally on the opposite side of the stack from edge portions 54 of the lower deflector. Deflectors 48 and 50 have free edges 60 and 62 which extend generally across the diameter of stack 22 and which are vertically displaced from each other to define a passageway 64 facilitating the flow of hot gases upwardly past the deflectors as shown by the arrows in FIG. 1. Passageway 64 has an effective area generally approximating that of the interior of stack 22.

Deflector 4% overlaps deflector 50 in a horizontal direction to prevent the falling heat-absorptive particles from penetrating to melt zone 13 in significant quantity. It makes little or no difference to operation of the cupola if small quantities of the particles do penetrate to the melt zone.

Expansion chamber 26 has an outlet 66 communicating into a pipe 68 which conducts cooled gases to a filter or collector 70 which is illustrated as being a conventional, commercially available, cloth-bag type collector. The collector is provided with an exhaust blower 72 operated by an electric motor 74.

Means are provided for cooling the heated particles issuing from discharge outlet 52 and for returning the cooled particles to hopper 30. In the illustrated system, these means comprise a stack 76 having an enlarged upper portion 78 forming an expansion chamber and having an open upper end 80. A hopper 82 is mounted by suitable means in expansion chamber 78, and this hopper may be identical in construction to hopper 30 having a bottom 38 and associated gate plate 42 provided respectively with openings 40, 44 distributed over their area for raining a torrent of the heated particles downwardly through stack 76. A chute 84 conducts the heated particles from discharge opening 52 into hopper 82 where they collect in a mass 86 on the bottom of hopper 82. A blower 88 blows a draft of cooling air upwardly through stack 76 and expansion chamber 78 for discharge upwardly out of open end 80.

Stack 76 has a bottom chute 90 which discharges the cooled particles into the inlet 92 of a bucket-type elevator 94 which returns the particles to chute 32 and hopper 30.

Any discrete, particulate, heat-absorptive material can be used which is sufficiently dense so that it will pass downwardly through stack 22 without being unduly impeded by the counter current of hot gases therein. Metal shot or particles, for example, could be used provided that the metal itself has a melting point higher than the temperature of the gases issuing from melt zone 13. However, sand is preferred because of its very low cost. A typical example of a sand suitable for use in the cupola is commercial grade foundry mold sand or bank sand having a grain size of about one-half millimeter.

in operation, it may be assumed that cupola has been charged and is in operation to produce a melt. Hot smoke-laden gases pass upwardly from melt zone 13 through passageway 64 and upwardly through stack 22 to expansion chamber 26 and then out of the cupola at outlet 66. With gate plate 42 properly adjusted to provide a desired extent and rate of heat exchange, a torrent of sand rains downwardly through stack 22 in a substantially free gravitational fall unimpeded except by the buoyant effect thereon of the upwardly flowing gases and the effect of deflectors 48, 50.

Since openings 40 and 44 in hopper bottom 38 and gate plate 42 respectively are generally distributed over the diameter of stack 22, the sand enters the stack in a plurality of generally uniformly distributed streams which insures that gases in all parts of the sectional area of the stack contact the particles. Moreover, within the stack, the streams are broken up or dissipated by the upwardly flowing gases which results in a thorough distribution of the sand particles within the stack and a consequent high rate of heat exchange between the gases and sand.

The same particles have a very large total surface area so that they quickly absorb heat from the gases. When the gases enter expansion chamber 26, they have been cooled to a temperature at which they will not damage collector 70. Upon passing through the collector, substantially all of the smoke particles carried by the gases are removed and the gases are discharged as clean air to the atmosphere through blower 72.

Expansion chamber 26 diminishes the velocity of the gases so that they drop whatever sand particles they may have carried upwardly into the expansion chamber, and such particles are not blown through outlet 66 to collector 70.

The mass of sand 36 in hopper 30 seals openings 40, 44 to prevent the escape of smoke-laden gases from the expansion chamber directly to the atmosphere. Deflectors 48 and cooperate to deflect the falling sand into receptacle 56 where the sand accumulates and forms a seal which prevents the escape of the gases through discharge opening 52. Movement of the sand over the surfaces of the deflectors tends to cool the deflectors and helps to prevent their overheating by the hot gases.

Deflectors 48 and 50 tend to form restrictions to the flow of gases in stack 22. ln general, however, these restrictions are compensated for by the draft resulting from rapid shrinkage of the gases above the restrictions and the suction of exhaust blower 72. If necessary, stack 22 could be provided with radial enlargements adjacent the deflectors to diminish or eliminate the restrictions.

A typical cupola 10 produces molten metal at a rate of about 12 tons per hour. The gases from melt zone 13 pass upwardly through the lower portions of stack 22 at a temperature of about 2,000 F. and at a rate of flow of about 25,000 cfm. The inner diameter of such a cupola is typically about 66 inches. In accordance with the present invention, a suitable height for stack 22 is about 16 feet measured from the top edge 62 of deflector 50 to the bottom 96 of expansion chamber 26. Accordingly, the sand, in its free gravitational fall, takes about 1 second to fall from openings 44 to receptacle 56. However, the upwardly flowing gases in the stack impede the fall of the sand to a certain extent and any given volume of gases and sand are in heat exchange contact for more than one second within stack 22.

In the l2-ton cupola under consideration, sand is rained downwardly through stack 22 at a rate of about 40 tons per hour. The mass 36 of sand in hopper 30 need not exceed that necessary to insure a continued rain through stack 22 during minor down time of elevator conveyor 94. As a practical matter, 5 to 6 tons is adequate to meet this requirement.

As the gases pass upwardly and are cooled, they shrink in volume commensurately. When they reach expansion chamber 26, the gases have been cooled to about 200 F., and their rate of flow has diminished to about 9,000 cfm because of their smaller volume. At this temperature, the gases cause no damage to collector 70. The gases enter outlet 66 traveling at a lineal velocity of about 500 feet per minute which is low enough so that, except for fines which may be contained in the sand, the sand is not blown into pipe 68.

The temperature of the sand is raised from ambient to about l,400 F. in passing from hopper 30 through stack 22 to receptacle 56, and the sand enters hopper 82 at somewhat less than that temperature. To cool the sand to about ambient temperature, stack 76 has an internal diameter of about feet, a height of about 16 feet between the outlet of blower 88 and the bottom of hopper 82, and blower 88 blows cooling air into stack 76 at about 58,000 cfm. The sand is returned to hopper 30 by elevator conveyor 94 at ambient temperature.

Expansion chamber 78 reduces the lineal velocity of the cooling air to below 400 feet per minute so that no sand is blown out of outlet 80 and the air need not be passed through a filter or collector. Clean air issues from outlet 80. This air is in heated condition and can be used for space heating or other purposes or can be discharged to the atmosphere.

The assembly of expansion chamber 26, its cover 28, and hopper 30 together with its mass 36 of sand is light enough so that it can be mounted on top of a conventional stack 22.

The cost of cupola modifications according to this invention installed and in operation, together with the accessory equipment illustrated, is about $40,000. Moreover, if a relatively large storage hopper or bin is available for heated sand issuing through chute 84, the sand could be allowed to cool simply by radiation, thereby eliminating entirely the cooling apparatus 76-90 and effecting a further savings of several thousand dollars. in comparison, the initial cost of a conventional apparatus for depolluting the gases from a l2-ton per hour cupola is about $200,000.

The operating cost of a cupola 10 according to this invention and its accessory equipment is very low, requiring only two or less relatively low power blowers 72, 88 and a relatively inexpensive elevator conveyor 94. The sand is an extremely cheap heat exchange medium, and it is recycled time after time rather than being expended. The cupola is not subject to clogging by smoke particles, and the cupola can be operated continuously without the necessity of periodic stoppages to permit cooling of the functional parts of the cupola or its accessory equipment.

I claim:

1. In a cupola having a melt zone adjacent its lower portion for receiving a charge and a stack for hot gases above said melt zone, improved structure which comprises,

said stack having a closed upper end,

a container mounted adjacent said upper end and having a body of solid discrete particles contained therein,

means operable to introduce particles from said container into said stack adjacent said upper end in the form of a substantially freely falling torrent distributed across a major portion of the diameter of said stack,

said stack having an opening in its side above said melt zon e,

deflector means in said stack effective to deflect said torrent of particles toward said opening for discharge from said stack,

said deflector means also forming shield means effective to shield said melt zone against entry thereinto of said particles in significant quantity,

said deflector means having elements spaced apart to define a passageway which facilitates flow of hot gases from said melt zone through said torrent toward said upper end,

said stack having an outlet for the gases adjacent said upper end,

and a filter connected with said outlet effective to remove particulate matter carried by the gases issuing through said outlet.

2. In a cupola having a melt zone adjacent its lower portion for receiving a charge and a stack for hot gases above said melt zone, improved structure which comprises,

said stack having a closed upper end,

a container mounted adjacent said upper end and having a body of solid discrete particles contained therein,

means operable to introduce particles from said container into said stack adjacent said upper end in the form of a substantially freely falling torrent distributed across a major portion of the diameter of said stack,

said stack having an opening in its side above said melt zone,

deflector means in said stack effective to deflect said torrent of particles toward said opening for discharge from said stack,

said deflector means also forming shield means effective to shield said melt zone against entry thereinto of said particles in significant quantity,

said deflector means having elements spaced apart to define a passageway which facilitates flow of hot gases from said melt zone through said torrent toward said upper end,

said stack having an outlet for the gases adjacent said upper end,

and a filter connected with said outlet effective to remove particulate matter carried by the gases issuing through said outlet,

said deflector elements comprising a lower element and an upper element,

said lower element cooperating with the interior of said stack to form a receptacle for collecting said particles in a mass,

said opening being adjacent the bottom of said receptacle to facilitate discharge of the massed particles therethrough,

said mass forming a seal which contains the gases from escape through said opening.

3. The structure defined in claim 2 wherein said upper element is effective to deflect portions of said torrent toward said receptacle.

4. The structure defined in claim 3 wherein said elements are disposed adjacent diametrically opposite portions of the stack interior, and each extends more than half way across the diameter of said stack so that said elements overlap in a horizontal direction to form said shield means.

5. The structure defined in claim 4 wherein the overlapped portions of said elements terminate in edges which are spaced apart in a vertical direction to define said passageway.

6. In a cupola having a melt zone adjacent its lower portion for receiving a charge and a stack for hot gases above said melt zone, improved structure which comprises,

said stack having a closed upper end,

a container mounted adjacent said upper end and having a body of solid discrete particles contained therein,

means operable to introduce particles from said container into said stack adjacent said upper end in the form of a substantially freely falling torrent distributed across a major portion of the diameter of said stack,

said stack having an opening in its side above said melt zone,

deflector means in said stack effective to deflect said torrent of particles toward said opening for discharge from said stack,

said deflector means also forming shield means effective to shield said melt zone against entry thereinto of said particles in significant quantity,

said deflector means having elements spaced apart to define a passageway which facilitates flow of hot gases from said melt zone through said torrent toward said upper end,

said stack having an outlet for the gases adjacent said upper end,

and a filter connected with said outlet effective to remove particulate matter carried by the gases issuing through said outlet,

said deflector elements including an upper element and a lower element,

said upper element extending across a portion of the diameter of said stack and being sloped to deflect the particles impinging thereon toward the side of said stack having said opening,

said lower element extending across at least the remaining portion of the diameter of said stack for impingement by particles both deflected by and passing freely of said upper element,

said lower element being sloped to deflect particles impinging thereon toward said opening.

7. The structure defined in claim 6 wherein there is vertical spacing between said elements which forms said passageway.

8. The structure defined in claim 7 wherein there is a horizontal overlap of said elements which provides said shield means.

9. In a cupola having a melt zone adjacent its lower portion for receiving a charge and a stack for hot gases above said melt zone, improved structure which comprises,

said stack having a closed upper end,

a container mounted adjacent said upper end and having a body of solid discrete particles contained therein,

means operable to introduce particles from said container into said stack adjacent said upper end in the form of a substantially freely falling torrent distributed across a major portion of the diameter of said stack,

said stack having an opening in its side above said melt zone,

deflector means in said stack effective to deflect said torrent of particles toward said opening for discharge from said stack,

said deflector means also forming shield means effective to shield said melt zone against entry thereinto of said particles in significant quantity,

said deflector means having elements spaced apart to define a passageway which facilitates flow of hot gases from said melt zone through said torrent toward said upper end,

said stack having an outlet for the gases adjacent said upper end,

and a filter connected with said outlet effective to remove particulate matter carried by the gases issuing through said outlet,

said stack having an enlarged diameter adjacent said upper end forming an expansion chamber for diminishing the rate of flow of said gases prior to passing into said outlet.

10. The structure defined in claim 9 wherein said container is mounted within said expansion chamber.

11. The structure defined in claim 10 wherein the top of said expansion chamber has a closure, said container being suspended from said closure within said expansion chamber.

12. The structure defined in claim 5 wherein said stack has an enlarged diameter adjacent said upper end to form an expansion chamber for diminishing the rate of flow of said gases prior to passing into said outlet.

13. The structure defined in claim 12 wherein said upper end is closed by a closure, said container being mounted on said closure.

14. In a cupola having a melt zone adjacent its lower portion for receiving a charge and a stack for hot gases above said melt zone, improved structure which comprises,

said stack having a closed upper end,

a container mounted adjacent said upper end and having a body of solid discrete particles contained therein,

means operable to introduce particles from said container into said stack adjacent said upper end in the form of a substantially freely falling torrent distributed across a major portion of the diameter of said stack,

said stack having an opening in its side above said melt zone,

deflector means in said stack effective to deflect said torrent of particles toward said opening for discharge from said stack,

said deflector means also forming shield means effective to shield said melt zone against entry the-l'einto of said particles in significant quantity,

said deflector means having elements spaced apart to define a passageway which facilitates flow of hot gases from said melt zone through said torrent toward said upper end,

said stack having an outlet for the gases adjacent said upper end,

and a filter connected with said outlet effective to remove particulate matter carried by the gases issuing through said outlet,

cooling means effective to cool particles discharged through said opening, and conveyor means operable to convey the cooled particles to said container.

15. In a furnace having a melt zone for metals and a stack for receiving hot gases from said melt zone, improved structure which comprises,

a closure adjacent the upper end of said stack,

a container mounted adjacent said upper end and having a body of solid discrete particles contained therein,

means operable to introduce particles from said container into said stack adjacent said upper end in the form of a substantially freely falling torrent disdiminishing the rate of flow of said gases prior to tributed across a major portion of the diameter of passing into said outlet. said stack, 16. The structure defined in claim 15 and including said stack having an opening below said torrent for egress of said particles,

conveyor means operable to return to said container particles which have issued from said opening whereby to recycle said particles,

said stack having an outlet for gases adjacent said upper end, 10

said stack having an enlarged portion adjacent said upper end which forms an expansion chamber for in addition means effective for cooling said particles between issuance thereof from said opening and recycling thereof.

17. The structure defined in claim and including in addition a filter connected with said outlet effective to remove particulate matter carried by the bases issuing through said outlet.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3972518 *Nov 23, 1973Aug 3, 1976Fuller CompanyCupola emission control system
US4033117 *Jan 8, 1976Jul 5, 1977The United States Of America As Represented By The Administrator, Environmental Protection AgencySolid fuel fired gas turbine system having continuously regenerating granular filter
US4248612 *Apr 12, 1979Feb 3, 1981Kobe Steel, LimitedApparatus for cleaning and recovering power from blast furnace exhaust gas
US4283223 *Sep 24, 1979Aug 11, 1981Air IndustrieProcess for treating smoke from steel plants
US4375982 *Aug 28, 1981Mar 8, 1983Klockner-Werke AgMethod for purifying a dust-containing hot gas, more particularly coal gas produced from coal fed into a steel or iron bath reactor
US4946486 *Oct 14, 1988Aug 7, 1990H. E. Technology, Ltd.Scrubber system for the removal of contaminants from a fluid stream
US5468282 *Feb 18, 1994Nov 21, 1995Asahi Glass Company Ltd.Method for operating a filtration apparatus for flue gas
Classifications
U.S. Classification266/157, 266/197, 96/373, 432/67
International ClassificationF27B1/18, F27B1/00
Cooperative ClassificationF27B1/18
European ClassificationF27B1/18