US3276757A

US3276757A - Blast furnace charging system

Info

Publication number: US3276757A
Application number: US327306A
Authority: US
Inventors: James H Owen
Original assignee: Kaiser Steel Corp
Current assignee: Kaiser Steel Corp
Priority date: 1963-12-02
Filing date: 1963-12-02
Publication date: 1966-10-04
Anticipated expiration: 1983-10-04

Description

oct. 4, 1966.

J. H. OWEN BLAST FURNACE CHARGING SYSTEM Filed Dec. 2, 1963 VIA/77'@ Ammin/sei CLEA/V 511957: Qua/ZEE ,Cum/4:5545

fJE/V) D@ ATTORNEY United States Patent O 3,276,757 BLAST FURNACE CHARGING SYSTEM James H. Owen, La Grange, Ga., assignerl to Kaiser Steel Corporation, Oakland, Calif., a corporation of Nevada Filed Dec. 2, 1963, Ser. No. 327,306 6 Claims. (Cl. 266-30) The present invention relates generally to systems for pressurizing blast furnaces, and more particularly to sys- -tems for blast furnaces having double charging bells at the top in which the pressure between the bells is increased and vdecreased with the furnace pressure to effect pressure equalization or over-pressure with relation theret0.

Blast furnaces are conventionally equipped with a charging arrangement comprised of an upper small bell and a small receiving and distributing hopper, cooperating with a lower large bell and a large receiving and dumping hopper. In operating a blast furnace with an increased gas pressure in its top portion, it is also known to provide an automatic means, also sequenced to the charging operations, for increasing and decreasing the pressure in the chamber between the bells with change in furnace pressure to maintain a desired differential or equalization therebetween.

To accomplish increase in pressure in the chamber between the bells, gas is bled from the top of the blast furnace, is cleaned, and controllably fed under pressure into the chamber to substantially equalize the pressure between the bells to the gas pressure in the top of the furnace. Means are provided for controlling the flow of this clean blast furnace gas in synchronization with the sequenced operation of the upper and lower bells. Such equalizer systems are well-known in the blast furnace art.

With ordinary equalizer operation there may still exist an undesirable pressure differential between the pressure in the top of the furnace and the equalized pressure between the upper and -lower bells due to pressure drop in 4the lines and to other factors which develop in large measure from warping of the lower bell and dumping hopper and the cutting of the seating surfaces therebetween by abrasive dust. The attainment and maintenance of equalized pressures at opposite sides of the lower bell minimizes or removes all -abrasive gas ow across the seating surfaces.

According to the present invention, the equalizer operation is supplemented by the operation of a booster system which is responsive to the pressure in the top of the furnace and in the chamber between the bells so that a differential therebetween (or a variation from a desired differential) effects flow of clean blast furnace or inert gas into the bell chamber to increase the pressure therein until it is equalized to the pressure in the top of the furnace. This booster system control is preferably synchronized with the sequenced operation of the upper and lower bells.

The booster system of the present invention may be used alone in a blast furnace operating at normal top pressure to establish and maintain an equal or over-pressure in the bell chamber with relation to the pressure in the top of the furnace to eliminate 'abrasive gas flow from the furnace into the chamber. In blast furnaces operating at increased top pressure, the booster system of this invention may also be used alone but will normally be used to supplement the operation of -a conventional equalizer system to insure the establishment and maintenance of equal pressures in the bell chamber and in the top portion of the furnace,l or a desired differential therebetween.

Mice

The above and other features and objects of the present invention will be apparent to those skilled in the art from the following specification land the appended drawing in which the figure is a `diagrammatic representation of a blast furnace and equalizer booster system according to the present invention.

In the figure, a blast furnace 11 is diagrammatically illustrated as having a frusto-conical upper shell 12 .on which is mounted a lower, receiving and dumping hopper 13 having a lower, large bell 14 seating thereagainst in closing relation. Above the hopper 13 is mounted a small frusto-conical shell section 15 and above this is supported an upper, receiving and distributing hopper 16 having associated `therewith an upper, small bell 17 seating thereagainst in closing relation. The bell 17 has an operating tube 18 extending upwardly therefrom by which the bell may be m-oved vertically to open and `close the hopper 16. A rod 19 is connected to the lower bell 14 and extends upwardly in sliding relation through the tube 18 so that the movement of the rod 19 effects independent vertical movement of the bell 14 into opening and closing positions.

Thebell chamber 20 between the bells 14 -and 17 is connected by a tube 21 to a conventional equalizer system 2 2. This system is well-known in the blast furnace art and operates to feed clean blast furnace or inert gas into the bell chamber to equalize the pressures therein and in the top portion of the furnace. The desired pressure in the blast furnace top may be maintained by controllably bleeding the gas therefrom as by a conduit 23. This may provide normal pressure or any desired overpressure operation, for example, at from 4-25 p.s.i. over atmospheric pressure. The vented gas may be cleaned and pressurized and fed into the equalizer system 22, as well as to the booster system of the present invention, as indicated at the legend 24.

The equalizer booster system according to the present invention has a supply pipe 25 for clean blast furnace or inert gas which feeds through a filter 26 to a compressor 27 driven by an electric motor or other drive 28. The compressed gas feeds through a check valve 29 and a shutoff valve 31 to a gas receiver 32. To the line to the receiver is connected a drip leg 33 connected by a valve 34 to a blow-down tube 35. Pressure within the receiver 32 is limited by a safety valve 36 which vents to atmosphere, and the receiver may be controllably purged to atmosphere, as desired, by a valve 37. The pressure in the top of the blast furnace 11 is connected to one side of a differential pressure switch 38, as by a pipe 39, and the pressure in the bell chamber 20 is connected to the other side of the differential pressure switch, as by pipe 41. The contacts of the differential pressure switch 38 control the energization and de-energization of a solenoid control valve 42 so that the valve is closed when the pressures in the bell 4chamber 20 and in the top of the furnace are equal, or at a desired differential, and the valve opens when the pressure in the top of the furnace exceeds the pressure in lthe bell chamber, or is above a de-sired differential with respect thereto. When the valve 42 opens, gas is fed from the receiver 32 through the pipe 43 into y the bell chamber to increase the pressure therein until it The equalizer system 22 is conventionally interlocked with the bells 14 and 17, as diagrammatically represented by the dash lines 44 and 45, to effect synchronous operation of the equalizer system with the sequential operation of the charging bells.

Likewise, a control valve 46 may be placed in the line 43 and be synchronized with the sequenced operation of the bells 14 and 17 by interlock means indicated diasrrammatically at 47 and 48.

The operation of the equalizer system and the equalizer booster system of the present invention during the charging of the blast furnace 11 will now be described. Furnace charging material is conveyed to the furnace in known manner and dumped into the receiving and distributing hopper 16, the hopper being closed by the bell 17. Prior to opening the bell 17, the chamber 20 may be vented to atmosphere through the equalizer system and the supply of gas through the equalizer and booster systems be shut off by operation of the interlocking means 45 and 48. In another manner of operation the bell 17 may be lowered while the pressure is held in the bell chamber 20 and the pressurized gas permitted to escape upwardly through the charging material and the hopper 16 to atmosphere. In either operation, the supply of gas to the bell chamber may be interrupted, or may continue and vent to atmosphere.

Lowering the bell 17 deposits the charging material in the receiving and dumping hopper 13 closed by the lower bell 14. The bell 17 i-s now returned to its closing position and the interlock means 45 and 48 reactivate the equalizer and the booster systems to re-establish the pressure in the bell chamber 20 at the desired value. When pressure equalization or the desired differential is attained, the lower bell 14 is lowered to dump the charging materials into the blast furnace. During the dumping in equal pres-sure oper-ation, the interlock means 45 or 48, or both of them, may be set to increase the flow of gas into the bell chamber 20 to preclude any movement of raw blast furnace gas past the bell seat into the chamber. Where an over-pressure is maintained in the bell chamber, the normal functioning of the control will effect such operation.

While the description heretofore has referred to equalizing the pressures in the bell chamber and in the top of the furnace, the term equalizing is to be construed to include the establishment of an over-pressure in the bell chamber at a desired differential above the pressure inthe top of the furnace to insure against the flow of the raw blast furnace gas past the bell seat into :the bell chamber. The attainment of equality or a desired differential between the bell chamber pressure and the pressure in the top of the furnace are both included in equalizing the two pressures. In operation with over-pressure in the bell chamber, the differential transducer, such as the differential pressure switch 38, will be set to regulate the pressures at the desired differential.

In the normal operation of the blast furnace with the bells 14 and 17 closed, the pressure of the gas in the top of the furnace will tend to fluctuate during operation and excess gas is bled off through the conduit 23 for use in the same or other blast furnaces, or for general disposition. The equalizer system 22 will operate in known manner to supply clean blast furnace or inert gas to the bell chamber 20 to substantially equalize the pressure in the bell chamber to that in the top of the furnace. Because of line drop and other factors, the attainment of the desired pressure in the bell chamber 20 may not be reached and the differential pressure transducer 38 is responsive to the differential between the pressures in the bell chamber and the top of lthe furnace to actuate the control valve 42 to supply additional blast furnace or inert gas to the bell chamber 20 to bring the pressure therein to the desired value.

It will be understood that, where desired, the equalizer system 22 may be omitted and the booster system itself be given sufiicient capacity to supply all of the pressurizing gas to the bell chamber 20.

While certain preferred embodiments of the invention have been specifically illustrated and described, it is understood that the invention is not limited thereto as many variations will be apparent to those skilled in the art, and the invention is to be given its broadest interpretation within the terms of the following claims.

What is claimed is:

1. A pressurizing system for a blast furnace having a bell chamber thereabove defined by a pair of upper and lower charging bells comprising: a source of gas under pressure; a differential pressure transducer; means connecting said transducer to the pressures in the top of the blast furnace and in said bell chamber, means responsive to said transducer for controllably feeding the gas from said source into said bell chamber to establish a pressure therein having a desired relation to the pressure in the top of the blast furnace as determined by the setting of said transducer.

2. The blast furnace pressurizing system defined in claim 1 in which said differential pressure transducer is a differential pressure `operated electric switch, and said means for controllably feeding the gas includes a solenoid valve the position of which is controlled by the oper-ation of said switch.

3. In a blast furnace having a bell chamber thereabove defined by upper and lower charging bells, an equalizer system including a supply of clean blast furnace gas and means for feeding said gas into said bell chamber to establish a pressure therein having substantially a desired differential with respect to the pressure in the top of the blast furnace; means responsive to the differential between the pressures in said bell chamber and in the top'of the blast furnace; and means controlled by said `differential pressure reponsive means for controllably feeding gas under pressure to said bell chamber to supplement the flow from the equalizer system and insure the maintenance of the pressure in said bell chamber at the desired differential above the pressure in the top of the blast furnace.

4. In a blast furnace having a bell chamber thereabove defined by upper and lower charging bells, an equalizer system including a supply of clean blast furnace gas and means for feeding said gas into said bell chamber to substantially equalize the pressure therein `to the pressure in the top of the blast furnace; means responsive to the differential between the pressures in said bell chamber and in the top of the blast furnace; and means controlled by said differential pressure responsive means for controllably feeding gas under pressure to said bell chamber to supplement the flow from the equalizer system and insure the maintenance of the pressure in said bell chamber equal to thepressure in the top of the blast furnace.

5. In a blast furnace having a bell chamber thereabove defined by upper and lower charging bells, an equalizer system including a supply of clean blast furnace gas and the pressures in said bell chamber and in the top of the blast furnace to be responsive to the differential therebetween; and means controlled by said differential pressure responsive meansifor controllably feeding gas to said bell chamber to supplement the flow from the equalizer system and insure the maintenance of the pressure in said bell chamber equal to the top of the blast furnace.

6. In a blast furnace having a bell chamber thereabove defined by upper and lower charging bells, an equalizer system including a supply of clean blast furnace gas and means for feeding said gas into said bell chamber to establish a pressure therein having substantially a desired differential with respect to the pressure in the top of the blast furnace; means responsive to the differential between the pressures in said bell chamber and in the top of the blast furnace; means controlled by said differential References Cited by the Examiner pressure responsive means for controllably feeding gas UNITED STATES PATENTS under pressure to sa1d bell chamber to supplement the flow from the equalizer system and insure the mainten- 211921885 3/1940 Avery 266-30 ance of the pressure in said bell chamber at the desired 5 2211872 9/1940 FOX et al 266- 27 diierential labove the pressure in the top of the blast fur- 2,408,945 10/1946 M01? et al- 266-'27 nace; and means interlocking said upper and lower bells 2,411,487 11/1946 Whltcomb 266-'27 2,602,027 7/ 1952 Old 266--30 to said equalizer system and supplemental gas feeding means to synchronize the control of the equalizer and supplemental gas ows with the sequential operation of the 10 JOHN F CAMPBELL Primary Exammer bells in effecting a furnace charging operation. M. L. FAIGUS, Assistant Examiner.