US3201225A

US3201225A - Method and apparatus for tapping furnaces

Info

Publication number: US3201225A
Application number: US317566A
Authority: US
Inventors: John A Haynes
Original assignee: Jet Research Center Inc
Current assignee: Jet Research Center Inc
Priority date: 1963-10-21
Filing date: 1963-10-21
Publication date: 1965-08-17
Anticipated expiration: 1982-08-17

Description

Aug. 17, 1965 J. A. HAYNES 3,201,225

METHOD AND APPARATUS FOR TAPPING FURNACES Filed 001;. 21, 1963 INVENTOR 9 4 John A. Haynes ATTORNEY United States Patent O METHOD AND APPARATUS. FOR TAPPING J FURNACE John A. Haynes, Northridge, Calif assignor to let Research Center, Inc, Arlington, Tax, a corporation of Texas Filed Oct. 21', 1963, Ser. No. 317,566 11 Claims. (ill. 75-28) This invention relates to methods and apparatus utilizing shaped explosive charges for tapping furnaces. The invention is particularly adapted for use in tapping open hearth furnaces.

O-pen hearth furnaces are generally tapped by either of two methods. In one method an oxygen lance is used to burn through the hot metal crustat the interior end of the furnace tap hole. In anothermethod an insulated shaped explosive charge is used to produce a jet which pierces the hot metal crust. The method using the insulated shaped explosive charge has gained wide acceptance because of the increased safety to the furnace workmen provided there-by. A workman can initiate the tapping operation at a remote location when using the shaped explosive charge'and is not in close proximity to the exit path of molten metal as is the case when the oxygen lance is used to tap-the furnace.

A method and apparatus for tapping blast furnaces using 'hea-t insulated shaped explosive charges is disclosed by Bruce Scott Old in his United States- Patent No. 2,563,131 issued August 7, 1 951, for Tapping Blast Furnaces .and the Like. .The present invention is an improvement of the method and apparatus disclosed in the Old patent. i l i The temperature at the end of an open hearth furnace tap hole adjacent the hot metal crust is around 2,000 F. The high temperature severely limits the time an insulated shaped-explosive charge may remain in place'in a tap hole without heat causing auto-detonation of the electric It is another object of thisinvention to provide a method of tapping an openhearth furnace using a shaped explosive charge apparatus wherein the apparatus may be placed in the tap hole and left for an extended period of time without damage totheapparatu's.

It is also an object of this invention-to provide a shaped explosive chargeapparatus that may be used after long exposure to hightemperatures. V

It is a further-object ofthis invention to provide "a shaped explosive charge apparatus that maybe placed in the tap hole of an open hearth furnace andleft for an extended period of time without damage to the apparatus.

The foregoing andother objects of the invention as may appear hereinafter are realized in one aspect in a method of tapping a furnace having a tap hole extending through a wall of the furnace and a plug closing the tap hole. The furnace contains a body of molten metal and a layer of crust lying against the inner end of the plug and the inner surface of the furnace wall contiguous to the plug. The method includes the steps of removing at least a portion of the plug to provide an elongated opening; positioning a shaped explosive charge in the opening with the jet-forming end of the charge facing the inner end of the opening; passing innocuous gas at high A misfire of the tapping charge re ice velocity over the charge to cool the same; and detonating the charge to form a jet that pierces the solid material between the inner end of the opening and the body of molten metal to provide communication between the in terior of the furnace and the opening to allow the molten metal to drain from the furnace.

The objects of the invention relating to the apparatus aspects are realized in an apparatus for tap-ping a furnace or the like, which includes an elongated hollow housing. A shaped explosive charge is contained within the housing adjacent one end thereof. Means is provided that is adapted to direct .aflow of innocuous gas through the housing and over the charge to cool the charge. Means .to detonate the shaped explosive charge is also provided.

Other objects, advantages and features of the invention will be apparent from a reading of the following description when taken in conjunction with the accompanying drawings wherein:

FIGURE I is a sectional elevation view of an open hearthfurnace with the tap hole plug drilled out and an apparatus constructed in accordance with the invention for tapping the furnace in place in the opening in the tap .the tap hole plug 14.

hole;

FIGURE 2 is a longitudinal sectional view of one em-' 7 FIGURE 4 is a longitudinal sectional view of another:

embodiment of a shaped charge explosive apparatus constructed in accordance with the present invention; and

FIGURE 5 is a longitudinal sectional view of an exemplary shaped explosive charge unit suitable for use in the apparatus illustrated in FIGURES 2 and 4.

. Referring now to FIGURE 1, the open hearth furnace, designated generally by the numeral 10, has a metal sidewall 141 lined on the interior with firebr-ick '12. The floor (not shown) of the furnace is also lined with fire, brick .12. A tap hole 13 is provided which extends through the sidewall 1-1 and the firebrick 12 lining of the furnaceto the interior of the furnace. filled with a dolomite or fire-clay plug 14 be fore the furnace is charged. The heat from the furnace hardens the plug and prevents the molten metal 15 from flowing out of the tap hole 13. A solid crust 16 of metal builds.

up during operation of the furnace on the fir'e'brick 12 [forming the sides and bottom of the furnace. A portion of the crust 16 overliestheinner. end 17 of the tap: hole pug V The method of tapping the furnace according to the present invention is carried out by making a hole 18 'in The hole 18 may not extend I completely through the plug 14, butis terminated about 6'to 8 inches short of the outer face of the crust 16 which overlies the inner end 17 of the tap-hole plug. These few inches of solid plug prevent the molten metal 15 from breaking through the crust '17 over the taphole in case the crust has a thin spot therein. The cuttings of dolomite are blown from the hole 18 by a stream of compressed air. A shaped explosive charge tapping ap paratus, designated generally 19, is inserted in the hole 18 in the dolomite plug 14. A high velocity stream of innocuous gas,- which may be compressed air, nitrogen,

or other unreactive gas, .is supplied to the tapping app'aratus'by means of a flexible hose 20 to keep the shaped explosive charge unit (to be described hereinafter) cool.

When the molten metal 15 reaches the desired metals.

l urgical composition electric current is applied through a pair of lead wires 21 to detonate the shaped explosive charge. The jet stream formed by the detonating shaped charge penetrates the solid plug of dolomite sealing the The tap hole is.

3 inner end 17 of the tap hole and the crust 16 of red hot metal overlying the end of the tap hole permitting the molten metal to drain through the opening 18 in the dolomite plug into a ladle (not shown) positioned at the front of furnace.

Referring now to FIGURE 2, one embodiment of a shaped explosive charge apparatus 19 constructed in accordance with the present invention is illustrated. The apparatus has an elongated, hollow, cylindrical outer housing 22 which is closed on its forward end by a friction-fit cylindrical cap 23. An elongated, hollow, cylindrical inner housing 24 is mounted coaxially within the outer housing. The inner housing has a smaller diameter than does the outer housing and is slightly shorter in length than the outer housing. A U-shaped, friction-fit annular end cap 25 joins the rear ends of the inner and outer housings and also serves to space the inner housing from the outer housing. The forward end of the inner housing terminates short of the end cap 23 and is supported centrally within the outer housing by a series of spaced Z brackets 26 as may be more clearly seen in FIGURE 3. These brackets may be spot welded to the inner and outer housings, or they may be attached by screws or other means. The rigid mounting of the smaller inner housing inside the larger diameter outer housing provides a uniform annular space 27 between the two housings extending from the rear of the two housings to the forward end of the inner housing. A short collar 28 surrounds a small gas inlet opening 29 in the wall of the outer housing adjacent its rear end. One end of a flexible hose is fitted over the collar to supply compressed gas to'the apparatus.

' A shaped charge explosive unit, designated generally 30, is mounted coaxially within the inner housing 24 adjacent its forward end by means of a series of spaced Z brackets 26a. The Z brackets support a mounting ring 31 which has an inside diameter adapted to receive the shaped charge explosive unit 30 in a close sliding fit. An electric blasting cap 32 is mounted at the rear of the shaped charge unit 30. A pair of lead wires 21 extends from the blasting cap through the open rear end of the inner housing to a source of electric current. The arrows shown in FIGURE 2 give the direction of the gas flow through the apparatus when it is in place in a hot tap hole. Compressed gas at or near ambient temperature fiows at high velocity from hose 20 into the annular space 27 between the inner and outer housings, thence to the forward end of the outer housing where it strikes the end cap 23 which reverses the direction of the flow causing the gas to pass over and around the shaped charge unit 30 to cool the unit. The cap 23 also serves as a deflector to cause a portion of the gas to impinge on the hollow face of the charge unit 30 to cool the liner. The gas is then exhausted to the atmosphere through the open rear end of the inner housing.

The inner and

outer housings

22, 24 and the end caps 23, of the apparatus are preferably made from light gage sheet metal. The

housings

23, 25 may consist of suitable lengths of a commercially available stove pipe or gutter drain pipe. Since the apparatus is designated to beexpendable, it is desirable to used the most economical materials for constructing the device consistent with the requirement that the materials be able.

to survive exposure to the 2,000 F. temperature without damage. The heat insulation properties of the material of construction is not critical since the apparatus functions by removing the heat from the shaped charge unit by cooling with high velocity gas rather than attempting to prevent the heat from the tap hole reaching the charge unit by providing insulating material around the charge unit,

Referring now to FIGURE 5, a shaped charge explosive unit 30 adapted for use in the tapping apparatus and method of the present invention is illustrated. The unit has a cylindrical case 33 open at the forward or jetforming end thereof. The case may be made of metal, plastic or other suitable material. The case contains a detonating explosive charge 34 which is preferably highly compressed desensitized cyclonite (cyclotrimethylenetrinitramine). Cyclonite has a relatively high melting point, (399 F.) compared to most other commercially available detonating explosives. A pellet of booster explosive 35 surrounds the portion of the integrally formed detonator cup 36 which extends into the hollow of the case 33 at the rear thereof. An electric blasting cap 32 is seated in the detonator cup. A thin conical metal liner 37 is seated against the conical wall 38 defining the cavity in the forward end of the explosive charge 34.

Referring now to FIGURE 4, another embodiment of a shaped explosive charge apparatus 19a constructed in accordance with the invention is illustrated. This form of apparatus has only a single housing 24a having about the same diameter and length as the inner housing 24 of the apparatus shown in FIGURE '2. A shaped charge unit 30 is received in a mounting ring 31 supported by Z brackets 26a positioned on the inside wall of the housing adjacent the forward open end of the housing. The rear end of the housing is closed by an end cap 25a, which may be integrally formed with the housing or in the form of a friction-fit cap such as shown in FIGURE 2. The end cap is provided with an axial gas inlet oepning 29a surrounded by an upstanding collar 28a which receives the end of a flexible hose 26 to supply compressed gas to the housing to cool the shaped charge unit. A bulkhead electrical connector 39 carries the pair of electrical leads 21 through the end cap 25a. A series of J-shaped gas deflectors 40 are attached to the inner wall of the housing immediately forward of the shaped charge unit. These deflectors act to reverse the direction of a portion of the cooling gas flowing in from the rear of the apparatus to cause the gas to impinge directly on the metal liner 37 of the charge unit 30 to remove heat therefrom. When the apparatus is placed in a tap hole in a furnace and compressed gas is supplied thereto, the gas will flow in the rear of the housing 24a'forwardly over the shaped charge unit 30 to cool the same, out the forward end of the housing, strike the end 17 of the tap hole plug 14 and then flow back out the hole 18 in the tap hole plug to the atmosphere. The direction of gas flow is indicated by the arrows in FIGURE 4.

It can be seen from the foregoing description and drawing that an improved method and apparatus for tapping blast furnaces and the like is provided which results in greater safety to the furnace workmen and decreases the chance of misfire resulting from overheating of the explosive material in the apparatus.

While the apparatus aspects of the present invention have been described with particular reference to use in tapping of open hearth furnaces and the like, such use is not exclusive. The shaped charge explosive devices of the present invention are suitable for use in any high temperature environment. One other use to which the devices are adapted is the perforation of the above ground section of the casing of 'a burning oil or gas well in order to provide an opening below the flame level which can be used to introduce fire extinguishing material (water, foam, etc.) to extinguish the fire or to pump mud into the well bore to kill the well. Another use of the apparatus of the present invention in perforating a burnmg storage tank to drain the flammable material from the tank into a surrounding fire pit where the material icianbe more readily covered with foam toextinguish the It is understood that the method and apparatus described herein are subject to wide modifications without departing from the spirit of the invention. Accordingly, the specific methods and apparatus described are to be considered merely illustrative and not as restricting the scope of the following claims.

I claim: 1

1. The method of tapping a furance having a tap hole extending through a wall of the furnace and a plug closing the tap hole, said furnace containing a body of molten metal and a layer of crust lying against the inner end of end of the plug and the inner surface of the furnace wall contiguous to the plug, which comprises:

(a) removing at least a portion of said plug to providean elongated opening therein;

(b) positioning a shaped explosive charge in said opening with the jet-forming end of said charge facing the inner end of'said opening; (c) passing a stream of innocuous gas at high velocity over said charge to cool the same; and l (d) removing said stream of gas from the zone of said charge; and

(e) detonating said charge to form a jet that pierces the solid material between the inner end of said opening and said body. of molten metal to provide communication between the interior of said furnace and said opening to allow said molten metal to drain from saidfurnace.

2. The method of tapping a furnace having a tap hole extending through a wall of the furnace and a plug closing the tap hole, said furnace containing a body of molten metal and a layer ofcrust lying against the inner end of the plug and the inner surface of the furnace wall contiguous to the plug, which comprises: rv r (a) removing at least a portion of said plugto provide an elongated opening therein;

(b) positioninga shaped explosive charge in said opening with the jet-forming end of said charge facing the inner end of said opening, said charge being spaced laterally from 'the'adjacent walls of said opening to permit substantially free flow of gas over said charge;

(c) passing a stream of innocuous gas at.high velocity over said charge to cool'the same; and

(d) removing said'stream of r gas from the zone of said charge; and v (e) detonating said charge to form a jet that pierces the solid material between the inner end of said opening and said body of molten metal to provide communication between the interior of said furnace and said opening to allow said molten metal to drain from said furnace.

3. The method of tapping a furnace having a tap hole extending through a wall of the furnace and a plug closing the tap hole, said furnace containing a body of molten metal and a layer of crust lying against the inner end of the plug and the inner surface of the furnace wall contiguous to the plug, which comprises:

(a) removing at least a portion of said plug to provide an elongated opening therein;

(b) positioning a shaped explosive charge in said opening with the jet-forming end of said charge facing the inner end of said opening;

(c) providing an inlet conduit to conduct a flow of innocuous gas from the exterior of said opening to the space surrounding said charge;

(d) providing an outlet conduit to conduct a flow of innocuous gas from said space surrounding said charge to the exterior of said opening;

(e) passing ,a stream of innocuous gas at high velocity into said inlet conduit, over said charge, and out said outlet conduit to cool said charge; and

(f) detonating said charge to form a jet that pierces the solid material between the inner end of said opening and said body of molten metal to provide communication between the interior of said furnace and said opening to allow said molten metal to drain from said furnace.

4. The method of tapping a furnace having a tap hole extending through a wall of the furnace and a plug closing the tap hole, said furnace containing a body of molten metal and a layer of crust lying against the inner end of the plug and the inner surface of the furnace wall contiguous to the plug, which comprises:

(a) removing at least a. portion of said plug to provide an elongated opening therein;

r (b) positioning a shaped explosive charge in said opening with the jet forming end of said charge facing the inner end of said opening, said jet forming end of said charge providing a cavity therein, the wall of said charge forming said cavity being lined with a metal liner;

(c) passing a stream of innocuous gas at high velocity over said charge to cool the same;

(d) deflecting at least a portion of said stream of innocuous gas into direct contact with said metal liner to cool said liner; I a

(e) removing said stream of gas from the zone of said charge; and V j, r

(f) detonating said charge to form a jet that pierces the solid material between the inner end of said opening and said body of molten metal to provide communication between the interior of said furnace and said opening to allow said molten metal to drain from said furnace. I

5. An apparatus for tapping a furnace and the like comprising:

. (a) an elongated hollow housing;

. (b) a shaped explosive charge within said housing adjacent one end thereof; i

(c) means for directing a flow of innocuous gas through said housing and over said charge for cooling said charge; and v o (d) means for detonating said shaped explosive charge.

6. An apparatus for tapping a furnace and the like comprising:

(a) an elongated hollow housing;

j (b) a shaped explosive chargewithin said housing adjacent one end thereof, said charge having its jetforming end facing said adjacent end of said housing;

(c) means coupled to the other end of said housing for directing a flow of innocuous gas through said housing and over said charge for cooling said charge; and

(d) means for detonating said shaped explosive charge.

7. An apparatus for tapping a furnace and the like comprising:

(a) an elongated hollow housing;

(b a shaped explosive charge within said housing adacent one end thereof, said charge having its jetforming end facing said adjacent end of said housing;

(c) means mounting said charge within said housing for permitting substantially free flow of innocuous gas over said charge;

(d) means for directing a flow of innocuous gas through said housing and over said charge for cooling said charge; and

(e) means for detonating said shaped explosive charge.

8. apparatus for tapping a furnace and the like comprlsmg:

(a) an elongated hollow housing having an end closure at one end thereof;

(b) a shaped explosive charge within said housing, said charge being spaced from but adjacent to said end closure and having its jet-forming end facing said end closure;

(c) means mounting said charge within said housing, said means laterally spacing said charge from the inner walls of said housing for permitting substantially free flow of innocuous gas over said charge;

((1) conduit means attached to said housing for delivering a flow of innocuous gas into the space between said end closure and jet-forming end of said charge and thence over said charge for cooling the same; and

(e) means for detonating said shaped explosive charge.

9. An apparatus for tapping a furnace and the like comprising:

(a) an elongated hollow outer housing having an end closure at one end thereof;

(b) an elongated hollow inner housing mounted substantially within said outer housing, said inner housing having its outside walls spaced laterally from the inner walls of said outer housing and having one end terminating short of said end closure;

(c) a shaped explosive charge within said inner housing near that end of said inner housing which is adjacent said end closure, said charge having its jet forming end facing said end closure;

(d) means mounting said charge within said inner housing for permitting substantially free flow of innocuous gas over said charge for cooling said charge;

(e) means for directing a flow of innocuous gas through said housings and over said charge for cooling said charge; and

(f) means for detonating said shaped explosive charge.

10. An apparatus for tapping a furnace and the like comprising:

(a) an elongated hollow generally cylindrical outer 7 housing, said housing having at least one of its ends closed;

(b) an elongated hollow generally cylindrical inner housing mounted substantially within said outer housing, said inner housing having its outside walls spaced laterally from the inner walls of said outer housing and being open on both ends, one of said open ends terminating short of said closed end of said outer housing, the other end being sealed to said outer housing by a ring-shaped end wall;

(c) a shaped explosive charge within said inner housing near that end of said inner housing which terminates short of the closed end of said outer housing, said charge having its jet-forming end facingthe closed end of said outer housing;

(d) means mounting said charge coaxially within said inner housing for permitting substantially free flow of innocuous gas over said charge;

(e) conduit means connected to said outer housing for introducing a flow of innocuous gas from an external source into the annular space between said housings, whereby the gas will flow through the annular space around the open end of said inner housing and over the shaped explosive charge for cooling said charge; and

(f) means for detonating said shaped explosive charge.

11. An apparatus for tapping a furnace and the like comprising:

(a) an elongated hollow housing;

(b) a shaped explosive charge within said housing adjacent one end thereof, said charge having its jetforming end facing said adjacent end of said housing;

(d) means attached to said housing for directing a flow of innocuous gas through said housing and over said charge for cooling said charge;

(e) deflector means located forwardly of the jet-forming end of said charge for deflecting a portion of said gas to impinge on said jet forming end of said charge; and

(f) means for detonating said shaped explosive charge.

References Cited by the Examiner UNITED STATES PATENTS 748,935 1/04 Dunham 10224 2,563,131 8/51 Old 41 2,847,205 8/58 Hnilicka 7584.5

DAVID L. RECK, Primary Examiner.

WINSTONA. DOUGLAS, Examiner.

Claims

1. THE METHOD OF TAPPING A FURANCE HAVING A TAP HOLE EXTENDING THROUGH A WALL OF THE FURNACE AND A PLUG CLOSING THE TAP HOLE, SAID FURNACE CONTAINING A BODY OF MOLTEN METAL AND A LAYER OF CRUST LYING AGAINST THE INNER END OF END OF THE PLUG AND THE INNER SURFACE OF THE FURNACE WALL CONTIGUOUS TO THE PLUG, WHICH COMPRISES; (A) REMOVING AT LEAST A PORTION OF SAID PLUG TO PROVIDE AN ELONGATED OPENING THEREIN; (B) POSITIONING A SHAPED EXPLOSIVE CHARGE IN SAID OPENING WITH THE JET-FORMING END OF SAID CHARGE FACING THE INNER END OF SAID OPENING; (C) PASSING A STREAM OF INNOCUOUS GAS AT HIGH VELOCITY OVER SAID CHARGE TO COOL THE SAME; AND (D) REMOVING SAID STREAM OF GAS FROM THE ZONE OF SAID CHARGE; AND (E) DETONATING SAID CHARGE TO FORM A JET THAT PIERCES THE SOLID MATERIAL BETWEEN THE INNER END OF SAID OPENING AND SAID BODY OF MOLTEN METAL TO PROVIDE COMMUNICATION BETWEEN THE INTERIOR OF SAID FURNACE AND SAID OPENING TO ALLOW SAID MOLTEN METAL TO DRAIN FROM SAID FURNACE.