US3788621A

US3788621A - Charging head for a metallurgical furnace

Info

Publication number: US3788621A
Application number: US00270482A
Authority: US
Inventors: P Nieboer
Original assignee: Demag AG
Current assignee: Mannesmann Demag AG
Priority date: 1972-07-10
Filing date: 1972-07-10
Publication date: 1974-01-29
Anticipated expiration: 1991-01-29

Abstract

A charging head for a metallurgical furnace includes a hopper which is connected into a furnace head and terminates in an interior annular sealing seat which is closed by a small bell which is carried on a pull rod which extends through the hopper. A throat cover for the furnace particularly for shaft furnaces which are operable at high pressures, such as a pressure blast furnace; and with a hopper which is closeable from the atmosphere after it is charged with material intermittently; includes a sealing valve which is pivotable from an open position at which it lies in a bulging portion of the furnace head into a closed position in which the valve extends around the lower portion of the small bell and seals the lower end of the hopper. The valve includes an annular sealing lip which engages into a seat defined on the exterior of the hopper around the exterior of the bell and engages with the seat at a location above the sealing seat defined at the interior of the hopper and which is engaged by the small bell. The small bell dams the material at the outlet of the hopper and a lower larger bell provides a distribution for the material and is located within the furnace below the small bell. The valve provides a hermetic seal around the exterior of the small bell and separates the storage bunker from the furnace zone when it is closed.

Description

ate [19] Jan. 29, 1974 CHARGING HEAD FOR A METALLURGICAL FURNACE [75] Inventor: Pieter Nieboer, Kapellen, Germany [73] Assignee: Demag Aktiengesellschaft, Duisburg,

Germany 22 Filed: July 10,1972

21 App1.No.: 270,482

Related US. Application Data [63] Continuation of Ser. No. 32,921, April 29, 1970,

Primary ExaminerGeralcl A. Dost Attorney, Agent, or FirmJohn J. McGlew et a1.

[ ABSTRACT A charging head for a metallurgical furnace includes a hopper which is connected into a furnace head and terminates in an interior annular sealing seat which is closed by a small bell which is carried on a pull rod which extends through the hopper. A throat cover for the furnace particularly for shaft furnaces which are operable at high pressures, such as a pressure blast furnace; and with a hopper which is closeable from the atmosphere after it is charged with material intermittently; includes a sealing valve which is pivotable from an open position at which it lies in a bulging portion of the furnace head into a closed position in which the valve extends around the lower portion of the small bell and seals the lower end of the hopper. The valve includes an annular sealing lip which engages into a seat defined on the exterior of the hopper around the exterior of the bell and engages with the seat at a location above the sealing seat defined at the interior of the hopper and which is engaged by the small bell. The small bell dams the material at the outlet of the hopper and a lower larger bell provides a distribution for the material and is located within the furnace below the small bell. The valve provides a hermetic seal around the exterior of the small bell and separates the storage bunker from the furnace zone when it is closed.

7 Claims, 1 Drawing Figure CHARGING HEAD FOR A METALLURGICAL FURNACE This is a continuation of application Ser. No. 32,921 filed Apr. 20, 1970 and now abandoned.

SUMMARY OF THE INVENTION This invention relates in general to the construction of metallurgical furnaces and in particular to a new and useful throat cover for shaft furnaces which are operable by a high pressure method, particularly for pressure operated blast furnaces.

The invention is particularly directed to the throad cover for shaft furnaces which is provided around the lower end of a shaft hopper which is closeable at its lower end by a small bell which is movable upwardly by a pull rod to engage an internal annular seat defined at the lower end of the hopper. The invention relates to a furnace of a type, in which in addition to the small bell, there is provided a larger bell located below the discharge end of the hopper and within the furnace head at a location to provide a distribution of the charging material.

Various proposals are known for maintaining the throats of a blast furnace at pressures which are higher than one atomsphere excess pressure. The known devices are generally unsatisfactory because of the frictional wear which occurs at the bell seats. While coke and lime additives cause relatively low-friction charge materials, metallic constituents such as pieces of ore, sinters, and pellets cause frictional or wear difficulties. The greater the hardness of the materials which are charged into the furnace the greater the tendency toward the formation of surface ruts in the valve seats and the formation of channels which permit escape of the flue gases upwardly through the charging hopper. A particularly undesirable obstacle is the escaping of flue gas dust because it has a high temperature and a high temperature has an effect on the geometrical form of the throat of the bell and the sealing seat itself. Bells of relatively large diameter are especially subject to change of form in the course of time due to warping.

According to a known solution, a gas seal is formed between the furnace and the throat by the fact that the two-bells together with a throat pan will form some sort of sea]. A lower bell having a larger diameter than the rim of the throat pan and the gas pressure in the interior of the furnace is used to press the lower bell against the aperture rim of the throat pan. An upper bell, however, is pressed with its outer rim against the slanting surface of the throat pan by the charging material present in the throat pan. Thereby a stepped seal is effected so that there is a pressure gradiation present between the furnace zone and the throat. This known solution does not produce a lasting effect because the sealing surfaces of the lower larger bell still are subject to wear by the charged material. The situation is even worse for the upper bell because the sealing seat between the pan and the bell also undergoes frictional wear by the dropping material. A complicated factor is that the upper smaller bell must be pulled through the accumulated charged material when the throat cover is opened. Such a device therefore can be expected to have a useful sealing affect only temporarily. This involves a great risk of having to shut down the blast furnace for a short period of time in order to permit changing over of the throat cover. Working on throat covers is undesirable,

however, for the reason that this can be done only with gas masks because of the gas atmosphere.

In accordance with the present invention, there is provided a construction which provides a better gas seal between the furnace zone and the throat and one which permits higher pressures of operation without being subject to great wear and therefore which provides a much longer life than the known devices. The construction of the invention includes a hopper which is connected to the upper portion or head of a furnace and which is adapted to be sealed at the location of an interior annular seat at its lower end by a small bell. In addition, the invention provides a pivotal valve member or plate which includes an annular rim which engages against an exteriorly formed seat at the lower end of the hopper which is located in a plane which is above the annular seat defined on the interior of the hopper. The valve is mounted on a pivot shaft and it may be shifted downwardly and to one side of the hopper into a bulge formed at the upper portion of the furnace head. A feature of the inventive arrangement is that the small bell is assigned only a sealing function in respect to the stopping of the discharge of the charged material. It is not intended, however, that the small bell forms a gas tight seat at the lower end of the hopper. Therefore, the wear of the smaller bell which may nevertheless be of considerable diameter is therefore without any significance. With the inventive construction, a separate pivotal valve member which may be shifted during the period which it is opened to a position at which it is not subjected to the abrasive action of a falling material from the hopper, is located so that it can be pivoted backwardly into a sealing position after the bell is closed and the material discharged from the hopper is terminated. When the valve covering is removed gas can pass at the sealing seat of the smaller bell but the blast furnace operator is familiar with the practice of providing an adequate pressure equalization in the hopper beforehand. It is then possible to seal against the atmosphere without exposure to wear. 'It is also common practice to provide a pressure equalization in any event because otherwise large bells cannot be opened at all. This is because the gas pressure produces ton size forces acting in a direction against the direction of bell opening movement. It is expedient therefore, to open the covering only after the gas pressure equalization has been established.

A particularly advantageous arrangement of the invention is to provide a pivotal valve sheet shaft which carries a valve seat member on an arm which is affixed to the pivot shaft for rotational movement therewith. The valve seat member is pivotally mounted on a universal ball and socket joint of the arm and it includes an exterior concave portion which extends around the lower end of the small bell and which terminates in an annular sealing lip which engages into a rim on the exterior of the hopper to provide a sealing at a location which is above the internal rim and which is sealed by the bell within the hopper shaft. Pivotal movement of the valve sealing member is effected after pressure equalization has taken place and thereafter the small bell may be moved to clear the way for the charge material. The invention thus provides an arrangement in which two sealing functions may be carried out separately that is the sealing of the charged material against the flow thereof by the small bell and the sealing of the gas pressure of the furnace zone the valve sealing arrangement. The sealing lip of the valve is placed entirely outside the stream of the charged material and it is located on the exterior of the tubular hopper but within the heat of the furnace. The construction insures that the impingement of flue gas dust will be very limited because the pressure conditions insure that there is less escape of the flue gas between the hopper and the furnace zone than in the usual gas outlets of the blast furnace. A desirable arrangement provides a bulging fitting for the top of the furnace head which carries the lower end of the hopper shaft and which provides a space for the pivotal shaft of the valve and for accommodating the valve member itself when it is in an opened position at a location in which it is removed from the lower discharge end of the hopper. By connecting the valve member itself with a pivotal arm which is movable with the pivot shaft, the valve member may be easily centered over the sealing lip and any imprecisions of the suspension of the pivot lever or its pivot axis are cancelled out. Thus a correctly sealing seat of a covering and of the sealing lip is always insured.

A further advantageous arrangement of the invention is that the valve member in the form of a plate includes an annular concave portion which extends around the internal sealing seat which is closed by the bell and terminates in an annular lip which engages into the seat formed on the exterior of the hopper tube or shaft. The concave portion provides a downwardly arched portion below the rim of the bell and it permits the placing of the sealing seat at a location above the sealing seat for the bell. The construction also makes it possible to provide the pivotal ball and socketjoint connection for the valve member and the pivot lever for the member at a location which is relatively very high and located on the interior of the bell.

Accordingly, it is an object of the invention to provide an improved throat covering for the charging end of a hopper which is fitted into a shaft furnace which is operable at high pressure and which includes a bell which is movable upwardly for engaging against an internal annular seat defined at the lower end of the charging shaft, comprising a valve member which is pivotally carried at the end of a lever arm which is rotatable on a pivot shaft which is offset from the hopper shaft and which may be moved to a closing position to seal with the lower end of the hopper shaft at a location exteriorly of the bell.

A further object of the invention is to provide a throat covering for a shaft furnaces which are operable by the high pressure method and particularly for pressure blast furnaces having a storage bunker which is openable and closeable from the atmosphere for the material to be charged intermittently; and which comprises a small bell which dams the material at the outlet of a hopper and a lower larger bell for distributing the material located below the small bell, the construction including a single or multipart covering or valve member for hermetically enclosing and sealing around the seat of the bell and separating the storage bunker from the furnace zone.

A further object of the invention is to provide a metallurgical furnace construction and a throat cover for shaft furnaces which are simple in design, rugged in construction, and economical to manufacture.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings in which there is illustrated and described a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS The only FIGURE of the drawing is a partial transverse sectional view through the sealing closure of a blast furnace constructed in accordance with the invention.

GENERAL DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing in particular, the invention embodied therein comprises a blast furnace generally designated 50 which includes a furnace head portion 11 which is enclosed upwardly by a fitting which includes a bulge portion 12 and a hopper or charging shaft 1. The hopper 1 is connected between the throat of the furnace 50 and a storage bunker (not shown). The storage bunker also includes a sealing means for sealing the bunker at its connection to the hopper l.

The hopper 1 is closed at its lower end by a small bell 2 which is carried at the lower end of a pull rod 5 and which is secured to the pull rod by means of a securing nut 8 which is threaded on the threaded end 8 of the pull rod. The pull rod 5 is coated with an armor 6 as indicated. In the upward position of the pull rod 5 the bell 2 engages at its lower periphery with a sealing seat defined on the interior at the lower end of the hopper l and the material .which is charged from the storage bunker into the hopper l accumulates over the surface 4 of the small bell 22.

In accordance with the invention, valve sealing means generally designated 3 are provided for sealing the lower end of the hopper 1 at the throat of the furnace in addition to the small bell 2. The valve means 3 includes a valve member or a valve plate 14 which is universally pivotally mounted on a pivot lever 23 which is carried on a pivot shaft 24 for rotation therewith. In accordance with a feature of the invention the pivot shaft 24 is mounted within the bulge portion 12 so that the pivot lever 23 and the valve member 14 may be moved into the dotted line position within the space 13 of the bulge portion 12 in an open position at which all the parts are out of the material flow path.

In accordance with a further feature of the invention the lower end of the annular wall 9 of the hopper 1 is provided with an annular valve lip or sealing rim 16 which cooperates with an annular sealing rim 15 defined on the valve plate member 14. The lip 16 defines a seat which is located above the interior seat 10 which is closed by the bell 2. The valve plate member 14 is designed as a thin walled member which is arched downwardly or formed with a concave groove portion adjacent its periphery as indicated at 17. In addition, it forms a central bottom portion 19 which extends upwardly into the interior of the bell 2 in the closed position indicated in solid lines. This upwardly extending bottom portion 19 is provided with a ball member 20 which interengages with a socket formation 22 of the lever arm 23 and forms a universal ball and socket oint.

The pivot shaft 24 is operated from the exterior of the furnace by means (not shown) and it rotates to rotate the lever member 23 from the solid line closed position to the dotted line opened position indicated in the drawings. When the valve is in the opened position the small bell 2 may be moved downwardly to the dotted line position indicated to permit the downward flow of the charging material.

The furnace 50 also carries a larger bell 26 which is suspended from pull rods 27 (only of which are indicated). Each pull rod 27 includes an armor plating 6, and generally two such pull rods 27 are provided. The lower end of the pull rods 27 are advantageously covered with a streamline plating 30 at the location where the pull rod extends through the shell 29 of the large bell 26 in order to facilitate the flow of the falling material. The lower end of each pull rod 27 is secured to a bridge 31 which carries a central pin 32 engaged with the large bell 26. A head portion 33 of the bell is removable in order to permit access to the pin 32 if necessary. The lower bell 26 has a much larger diameter than the smaller bell and provides a different distributing function at the lower portion of the furnace head 1 1.

What is claimed is:

1. A throat cover for the charging hopper of a pressure operated blast furnace, comprising a charging hopper having a lower end adapted to be connected into the blast furnace and with a first sealing seat defined adjacent said lower end, a bell suspended within said hopper and being engageable with said first sealing seat to stop the flow of charging material and permit the accumulation of the material over said bell within said hopper, a second sealing seat defined adjacent the lower end of said charging hopper, a covering engageable with said second sealing seat for hermetically sealing said hopper from said furnace, said second sealing seat being defined exteriorly of said first sealing seat around the lower end of said charging hopper, said covering including a valve plate member having an annular rim-engageable with said second sealing seat, means for mounting said valve plate member for pivotal movement between a position at which it engages with said second sealing seat and a position in which it is positioned to one side of said hopper at a location out of the flow stream from the lower end thereof, a valve pivot shaft located to one side of said hopper, a lever arm connected to said valve point shaft for rotation therewith and connected at its opposite end to said valve plate member, said valve plate member having a rim of a larger diameter than said bell, said first sealing seat being defined on the interior of said hopper at the lower end thereof, said bell being movable with its lower rim into sealing engagement with said first sealing seat, said second sealing seat being located higher than said sealing seat.

2. A throat cover, according to claim 1, including a universal pivotal connection means between said plate member and said lever.

3. A throat cover, according to claim 1, including a ball and socket point at the location of said raised central portion of said plate member connecting said plate member to said lever arm.

4. A charging appartus for a pressure operated blast furnace, comprising a charging hopper adapted to be connected to a stationary storage bunker at its upper end and having a lower end adapted to be connected into the blast furnace and with a relatively small diameter first sealing seat defined at said lower end, a first bell suspended within said hopper and being engageable with said first sealing seat from below to stop the flow of charging material and permit the accumulation of the material over said bell within said hopper, a relatively large diameter second sealing seat defined adjacent the lower end of said charging hopper at about the level of said first seat, a swingable cover engageable with said second sealing seat for hermetically sealing said hopper and said bell and first sealing seat from said furnace, a second bell located within said furnace at a location below said first-mentioned bell, said second bell being substantially larger than said first-mentioned bell and serving as a distributor for material discharged through said charging hopper lower end and apex located below said first sealing seat, and a vertically movable pull rod extending into the blast furnace alongside said charging hopper and extending into a side of said second bell below the apex thereof and having a lower end extending below said second bell apex and pivotally supporting said second bell.

5. A throat cover for the charging hopper of a pressure operated blast furnace, comprising a charging hopper having a lower end adapted to be connected into the blast furnace and with a first sealing seat defined adjacent said lower end, a first bell suspended within said hopper and being engageable with said first sealing seat to stop the flow of charging material and permit the accumulation of the material over said first bell within said hopper, a second sealing seat defined adjacent the lower end of said charging hopper, a covering engageable with said second sealing seat for hermetically sealing said hopper from said furnace, said blast furnace having a furnace head portion, a bulge portion fitted over said furnace head portion and carrying said hopper, said bulge portion defining a laterally and upwardly opening recess extending outwardly from said head portion, said covering member including a valve member having a seating edge, a pivot shaft for said valve member located within said recess on one side of said hopper, and a bent lever arm carried by said shaft portion and rotatable therewith and connected to said valve member, said bent lever arm being movable with said head portion to position said valve member within said recess at a location where its seating edge is completely out of the path of the flow of material which is discharged from said hopper, a second bell located in the furnace below said first bell, and a pull rod extending into the furnace and partially supporting said second bell.

6. An apparatus for charging a pressure operated blast furnace, comprising a charing hopper adapted to be connected to a stationary storage bunker at its upper end and having a lower end adapted to be connected into the blast furnace and with a first sealing seat defined adjacent said lower end, first bell suspended within said hopper and being engageable with said first sealing seat to stop the flow of charging material and permit the accumulation of the material over said first bell within said hopper, a second sealing seat defined adjacent the lower end of said charging hopper, a covering engageable with said second sealing seat for hermetically sealing said hopper from said furnace, said blast furnace having a furnace head portion, a bulge portion fitted over said furnace head and carrying said hopper, said covering including a valve member, a pivot shaft for said valve member located within said bulging portion on one side of said hopper, a lever arm carried by said shaft portion and rotatable therewith and connected to said valve member and being movable with said shaft portion to position said valve member within said bulge portion of said furnace head at a location out of the path of flow of material which is discharged from said hopper, said plate member including an annular convex portion which extends downwardly around the rim of said bell and terminates in an exterior rim engageable with said second sealing seat, said valve plate member including a raised central portion extending into the interior of said bell, a second bell located in the furnace below said first bell, and a pull rod extending through said bulge portion into the furnace and through a side of said second bell and having a lower end portion pivotally supporting said second bell.

7. A throat cover, according to claim 1, including an additional bell located within said furnace at a location below said first-mentioned bell, said additional bell being substantially larger than said first-mentioned bell and serving as a distributor for material discharged through said charging hopper lower end and having an apex located below said first sealing seat, and a vertically movable pull rod extending into the blast furnace alongside said charging hopper and extending into a side of said additional bell below the apex thereof and having a lower end extending transversely below said additional bell apex and pivotally supporting said additional bell.

Claims

1. A throat cover for the charging hopper of a pressure operated blast furnace, comprising a charging hopper having a lower end adapted to be connected into the blast furnace and with a first sealing seat defined adjacent said lower end, a bell suspended within said hopper and being engageable with said first sealing seat to stop the flow of charging material and permit the accumulation of the material over said bell within said hopper, a second sealing seat defined adjacent the lower end of said charging hopper, a covering engageable with said second sealing seat for hermetically sealing said hopper from said furnace, said second sealing seat being defined exteriorly of said first sealing seat around the lower end of said charging hopper, said covering including a valve plate member having an annular rim engageable with said second sealing seat, means for mounting said valve plate member for pivotal movement between a position at which it engages with said second sealing seat and a position in which it is positioned to one side of said hopper at a location out of the flow stream from the lower end thereof, a valve pivot shaft located to one side of said hopper, a lever arm connected to said valve point shaft for rotation therewith and connected at its opposite end to said valve plate member, said valve plate member having a rim of a larger diameter than said bell, said first sealing seat being defined on the interior of said hopper at the lower end thereof, said bell being movable with its lower rim into sealing engagement with said first sealing seat, said second sealing seat being located higher than said sealing seat.