US3092680A - Blast furnace control system - Google Patents

Description

June 4, 1963 b. J. LEONE 3, 8

BLAST FURNACE CONTROL SYSTEM Filed Nov. 25, 1957 3 sheets-sheet 1 INVENTOR 0770 J, LEONE June 4, 1963 o. J. LEONE 3,092,680

BLAST FURNACE CONTROL SYSTEM Filed NOV. 25, 1957 3 Sheets-Sheet 2 4/ Riv f g 64 I 9 66 o o l INVENTOR 0770 d. LEONE J 4; 1963 o. J. LEONE 3,092,680

BLAST FURNACE CONTROL SYSTEM Filed Nov. 25, 1957 3 Sheets-Sheet 5 z INVENTOR orro u. LEONE limited btates 3,092,686 BLAST FURNACE CONTRGL SYETEM Otto J. Leone, P50. Box 24, West Newton, Pa. Filed Nov. 25, 1957, Ser. No. 698,811 3 Claims. (Cl. 266-339) This invention relates to a system for blast furnace control or the like and magnetomotive instrument constructions for use therewith. More particularly, my invention pertains to an alternative system for achieving benefits discussed in my copending application Serial No. 330,753, filed January 12, 1953, now Patent No. 2,814,479.

In my new system disclosed herein, an induced current construction is provided through magnetic means to sense an undue rate of change in a pressure variable to yield a corresponding induced current for the issuance of a corrective signal for blast furnace control or like purposes. By such means, a further relatively fast, low inertia and trouble-free construction is available to control a blast furnace or the like and keep it significantly free of hanging, scaffolding, packing and slipping troubles either when differential pressure control is being exercised as taught by my Patent No. 2,625,386, or otherwise. Further advantages, features and objects of my invention will be apparent from the following description and the accompanying drawings, which are illustrative only, in which:

FIGURE 1 is a schematic view of a blast furnace control system utilizing a new instrument construction disclosed herein;

FIGURE 2 is a schematic view of a further blast furnace control system utilizing such an instrument construction;

FIGURE 3 is a diagrammatic view of a new indicating instrument construction suitable for use in the system shown in FIGURES l and 2;

FIGURE 4 is a diagrammatic view of a modified indicator instrument construction;

FIGURE 5 is a partial view of a further modification of an instrument construction of this invention; and

FIGURE 6 is a view of an indicator instrument construction similar to that shown in FIGURE 3, but adapted to be responsive to a selected rate of pressure change in the opposite direction.

Referring to FIGURE 1 of the drawings, there is shown therein a blast furnace 10 to which a stock burden is supplied through a hopper 11 when a bell at the top is opened by a rod 12. Blast air is supplied to the bottom of the stack through a blast main or pipe 13 and gaseous products are taken off from the upper part of the stack through a top gas line or pipe 14 in which a normally closed relief valve 15 is usually provided. Blast main 13 is provided with a main relief branch 16 which is normally closed by a main relief valve 17 and is also provided with an auxiliary relief branch 18 having a valve 19 therein. Valve 17 is provided with an on-off operator 20, which may be in the form of a solenoid operator, while valve 13 preferably is provided with a proportioning operator 21 which enables valve 19 to be modulated from its fully closed to its fully open position. Gas line 14 normally communicates with a dust catcher and washer system 22 through which the gaseous products from furnace 10 are led. A top gas pressure control valve 23 is provided in line 14 and has a proportioning operator 24 for the modulation of valve 23.

As shown, the differential pressure within blast furnace 10 is controlled by a differential pressure controller 25 upon which is impressed normally the blast main pressure through a pipe tap 26 and the top gas pressure through a pipe tap 27. Such pipe taps may instead, if

3,092,680 Patented June 4, 1963 ice desired, be connected directly to and across the stack of furnace 10 as illustrated, for example, in the applicants Patent No. 2,625,386. Any corrective signal issued by controller 25 may be in the form of a pneumatic, hydraulic or an electrical impulse transmitted through a conductor 28 to operator 24, or through a conductor 29 to operator 21, or both, as determined by the overlap or interlock relay provision within controller 25, as desired, to maintain the differential pressure across stack 10 within that selected differential pressure range which will maintain furnace 10 relatively free from hanging, slipping, packing and other troubles. And, additionally, controller 25 may be operatively connected to the blower volume regulator to regulate its speed and delivery volume if that means is selected in maintaining an appropriate differential pressure through the blast furnace.

In addition, a top gas controller 30' is provided to act at least upon an abnormal rate of increase in the top gas pressure within gas line 14, such being an indication that the furnace 10 is heading for trouble, or at least is in the initial stages of a difliculty such as a slipping condition. The top gas pressure is impressed upon controller 30 through a pipe tap 31 and whenever any corrective signal is issued by controller 30 in the form of an electrical impulse, such will pass through a conductor 32 to operator 20 to open main relief valve 17 quickly and drop the pressure in the blast furnace system. Generally, such opening of the main relief valve to spill out blast air or wind will relatively quickly drop the top gas pressure to a desired level. If wished, controller 30 may also be hooked up to a relief valve in the gas line such as relief valve 15 or one farther from the furnace 10. The action of top gas controller 30 overrides the control action of differential pressure controller 25 until the excessive pressure rate condition or excessive pressure condition causing the issuance by controller 30 of a corrective signal impulse is remedied whereupon the system automatically returns to the control action of controller 25. Controller 30 is also provided with a high limit switch for the top gas pressure which when actuated will transmit a separate signal through an electrical conductor 32a directly to operator 20 to open valve 17.

As pointed out in the applicants aforesaid prior inventions, the controllers may be interlocked, for example, with the opening of the furnace bell so that the tendency of such opening to upset pressure conditions will not .invoke control action during such opening. Further,

controls, such as controllers 25, 3t and 34, may, if desired, have incorporated therein indicating, recording, metering or other auxiliary functions as will be readily recognized by those skilled in the art to whom this invention is disclosed.

In the further system illustrated in FIGURE 2, parts thereof generally corresponding in structure and functioning to those shown in FIGURE 1 are provided with the same reference numerals with the addition of a prime accent thereto, respectively. Therein, the differential pressure controller 25' also incorporates a differential pressure transmitter portion which pneumatically transmits through a pipe 33, a pneumatic impulse at the time of and corresponding to changes in the differential pressure existing across the pressure taps 26 and 27. The differential pressure impulse transmitted through pipe 33 is fed into a differential rate controller 34 which may be in the form of the instrument shown in FIG- URE 6 hereof. As and when the rate of change of the differential pressure becomes abnormal in a decreasing direction, a corrective impulse is sent out by controller 34 as an electrical impulse through a conductor 35 to a relay 36. Relay 36 is responsive so that it will transmit through conductor 38 a corrective signal to operator 20 when both controller 34 and controller 30 are issuing a corrective output impulse to relay 36, such impulse in the case of controller 3% being transmitted through conductor 32. Preferably, the characteristics of controllers 30' and 34 will be selected such that controller 36' will transmit its corrective impulse to relay 36 slightly ahead of the corrective impulse transmitted by controller 34 to relay 36.

In the case of the top gas pressure controller 36', the high limit pressure switch is separately connected to an electrical conductor 37 so that any actuation thereof will send an independent signal .to operator 2%) for the separate opening of valve 17 whenever the preset high limit on the top gas pressure is reached. On the other'hand, the rate of change parts of controller 3% are left connected to conductor 32 leading to relay 36, which may have an electrical network therein such as that illustrated in FIGURE 7 of my aforesaid copending application Serial No. 330,753, now Patent No. 2,814,479, in which the rate of change parts of controllers 30' and 34 are in series and actuated in sequential relation before an electrical signal can be sent over conductor'38 to operator 2 calling for the opening of main relief valve 17 in the blast main 13. As soon as the conditions causing the opening of valve 17' cease, the valve 17' will be closedby operator 20 and control of the operation of blast furnace will be automatically returned to controller 25 acting in a modulating fashion upon the operator 24 or 21, or both, or on the volume regulator of the blower, in selected, sequential or overlapping fashion as desired.

One embodiment 39a of a top gas pressure instrument suitable for use as controller 36 or 39 is illustrated in FIGURE 3 and may be mounted on a panel 39 which is suitably encased. The top gas pressure pipe 31 may be suitably connected to an impulse pipe 46 which extends to the interior of instrument 30a, a valve 41 such as a needle valve being provided in line/4i) for purposes of instrument adjustment and coordination with the system with which it is to be used. The lower end of pipe 40 communicates with the interior of a housing 42 having apressure sensitive resilient bellows 43 in sealed relation to an annular flange wall 44 at one end of housing 42, the remm'nder of the wall being formed by the bellows 43 which has its interior open to the atmosphere within instrument 30a. Bellows '43 is provided with a head 45 and as pressure variations occur in the input impulse pipe 40, head 45 correspondingly moves in one direction or the other with variations in the pressure transmitted through pipe 4tlto the interior of housing 42.

A rod 46 is provided with one end 47 fixed to head 45 and its other end 48 fixed to a magnetic member such as permanent magnet 49 extending in a coaxial direction relative to rod 46. Rod 46 is provided with an integral link 50 which may be used to pivotally connect rod 46 to a pressure responsive indicator arm'5l by means of apivot pin 52. Arm 51 is pivotally mounted at'53 on panel 39. As the diaphragm of bellows 43 moves axially, arm 51 will be correspondingly moved by rod 46, there being sufiicientflexibility in bellows 43 'to accommodate the arcuate action of pin 52 during such motion. A solenoid coil 54 is provided with an axial opening 55 in axial registry with the axis of magnet 49 and of a diameter such that magnet 49 can be thrust into coil opening 55 by movements of bellows 43 to the left irom any pressure position such as that illustrated in FIGURE 3. The'ends of coil 54 are respectively connected to terminals on a block 56 mounted on panel'39 and those respective terminals are connected to the leads 57 of a galvanometer 58 of any commercial type which is relatively fast and sensitive.

As shown, galvanometer '58 is provided with feeder springs 59 to bring shaft 66 and a pointer 61 carried thereby to a zero position on a scale 62 whenever there is no current flowing in the leads 57. Galvanometer 58 is provided with a magnet field 63a and core 63! with a circular gap 64 between in which a meter coil 65 can turn in accordance with any current flowing in the leads 57. A concentrically pivoted index arm 66 is adjustably movable along scale 62 to the selected setting. Arm 66 carries opposed spaced coils 76, leads 77 from which extend to a galvanometer terminal block 68 and from thence to an amplifier 69 which in turn is connected to a relay 70 operated by the amplifier output to control a switch for the sending of a corrective signal in the form of an electrical impulse from the terminals of output terminal block 71 through the wires in conductor 32 in the control system described above.

Swingable pressure arm 51 is also provided with a normally open high limit switch having a movable contact 72 which coacts with a fixed contact 73 adjustably mounted on panel 39 to be preset to the selected extent. As long as the electrical switch represented by the contacts 72 and 73 is open no current will flow in the leads 74, and vice versa. As and when contacts 72 and 73 do engage one another, current will flow in the conductor 32a to operator 2t and open main relief valve 17 to prevent the top gas pressure, as distinguished from any rate of change thereof, from exceeding a predetermined high limit. Power lines L and L are connected to terminal 67 to enable the wires in conductor 32a to be energized whenever contacts 72 and 73 close, whether or not such closure is accompanied by a sufilciently rapid axial movement of magnet 49 to produce a corrective signal output from galvanometer 58 such as occurs whenever flag 75 moves into the space between the opposed coils 76. It will be readily recognized that in place of such oscillatory coils 76, other commercial forms of meters may be used which utilize a light and photoelectric cell in opposed relation for interruption by an opaque flag, or which use contacts with a galvanometer for the production of a corrective signal output.

The magnetic pressure rate portion of instrument 30a is shown in the form of an indicator having the scale S along which the arm 51 is movable in accordance with the normally changing top gas pressure values. As shown, arm 51 will move clockwise about its pivot 53 upon the occurrence of an increase in the top gas pressure and counterclockwise upon a decrease therein from the shown position of head 45. Thus, even though the relative movement of magnetic member 49 into opening 55 may not be rapid enough to move pointer 61 to index position 66 at which the flag is between the coils 76, the pointer 51 will still indicate changes in the pressure within tap extension 46 just as pointer 61 will indicate all induced currents flowing in the leads 57 and their direction due to the direction of movementof member 49 relative to opening 55. In general, the limit of movement of member 49 into opening 55 is preferably about one-half of the length from the leading end thereof. Although the magnetic member 49 is shown with the north pole end leading, the polarity thereof could be reversed in which event the settings on the respective scales would have to be correspondingly displaced to the other side of the zero mark as would the high limit contacts 72 and 73 and the index arm 66.

In operation, so long as the rate of change of the top gas pressure does not rise in a pressure increasing direction to a value indicating that slipping may be incipient or under way, any movement of magnet 49 within coil opening 55 will not induce a sufiicient current in the coil leads and galvanometer leads 57 to drive pointer arm 61 to the index position preselected by the setting of arm '66, and, no corrective signal will be issued by controller 361a. On the other hand, whenever the top gas pressure in gas line 14 increases at a rate which is abnormal indicating the incipient or early stages of slipping, for example, the thrust of bellows head 45 to the left as viewed in FIGURE 3 will be more rapid and the consequent current induced in coil 54 will be greater and sutficient to move pointer 61 into substantial registry with index arm 66. When that occurs, a flag 75 passes between two opposed oscillation coils 76 carried by arm 66 in galvanometer 58. In so doing, the oscillatory energy in the system of the coils 76 changes. Such coils 76 are connected by leads 77 to terminal block 68 which in turn is connected as described above to amplifier 69 and relay 70. Such change produced by the passage of flag 75 between coils 76 causes a corrective signal in the form of an electrical impulse magnified in strength by the amplifier to pass through the conductor 32 to operator 20 to open main relief valve 17, thereby quickly dropping the blast main pressure, the differential pressure across the blast furnace stack and arresting the abnormal rate of increase in the top gas pressure. When that abnormal rate of increase is so arrested, the pointer arm 61 moves back toward its Zero position on the scale 62 and in so doing removes the flag from between the coils 76 with the result that there is a cessation of a signal sent out over conductor 32 from controller 300 which in turn causes operator 20 to return valve 17 to its normally closed position.

If, under some circumstances, the top gas pressure should increase toward a limiting pressure such as might be imposed by the strength of the seals on the dust catcher and washer system or the pressure limit strength of the top of the blast furnace, but at a rate insuflicient to produce an induced current in leads 57 which will cause flag 75 to pass between oscillatory coils 76, the system is nevertheless safeguarded because if, as and when contatcs 72 and 73 close, a current will pass through conductor 32a to operator 20 and open valve 17 for a period of time to reduce the pressure in gas line 14 to a safe value for the equipment used. As such pressure goes down, bellows 43 will automatically move to the right, as viewed in FIGURE 3, and disengage contacts 72 and 73, whereupon valve 17 will automatically close and the action of differential pressure controller 25 will remain as the controller for the furnace operation within the prescribed differential pressure limits subject thereafter as and when required to the overriding and overtaking nature of the safeguards provided by controller 30a.

In lieu of the top gas pressure controller 30a, a modified controller illustrated in FIGURE 4 may be used and parts therein generally corresponding in structure and functioning are provided with the same reference numerals as those shown for controller 30a with the addition of a prime accent thereto. In controller 30a, end 48' of rod 46' is provided with a movable corepiece 49 which, however, is not magnetized but is made of a magnetic metal like soft iron. A field is created for core 49 by a field solenoid coil 78 which is energized through leads 79 by a source 80 of direct current which may be adjusted in quantity by a rheostat 81, or any source of rectified alternating current which has been suitably filtered to reduce pulsating effects. Such excitation of coil 78 and flux passing through core 49' will cause it to induce an in coil 54 whenever rod 46' is moved by bellows 43. The more rapid such movement the greater the induced and when the rate of increase in the top gas pressure in gas line 14 or 14', as the case may be, becomes excessive, the rapidity of such axial movement of core 49' will be such that the coil leads to a conventional meter control and relay system 82, which may have signal elements therein in the form of galvanometer 5S, amplifier 69 and relay 70 shown in controller 30a, or some other automatic control such as a contact meter with a built-in relay, or any suitable commercial fast-acting potentiometric controller. Thus, a corrective signal is issued to the terminals on the block 71' and conductor 32 (or '32), as the case may be, whenever such top gas pressure rate is abnormal. Further, as and when contacts 72 and 73' engage, current 6 will flow through the conductor 32a (or 37) for the purpose described above.

A further modification in such a controller is illustrated in FIGURE 5 which shows that only certain parts thereof have been changed. Parts shown in FIGURE 5 corresponding generally in construction and functioning to parts shown in FIGURES 3 and 4 are marked with the same reference numeral with the addition of a double prime accent thereto. In such further modification, corepiece 49" is made into an electromagnet by an exciting coil 83 connected thereto. Exciting coil 83 is energized by flexible leads 84 which are connected to a direct current source through a rheostat 81' (or suitably rectified and filtered alternating cur-rent). The action and operation of such further modification shown in FIGURE 5 are like those of the controllers illustrated in FIGURES 3 and 4.

The new instrument construction illustrated in part in FIGURE 6 is like the controller 30a shown in FIGURE 3 except that the FIGURE 6 construction is adapted to operate upon the occurrence of an excessive rate of pressure change in a decreasing direction and, as such, is utilizable as the differential rate controller 34 in the FIGURE 2 system. Further, the FIGURE 6 instrument has no limit switch (contacts 7273). The parts of the construction shown in FIGURE 6 which correspond generally in structure and function to parts shown in FIGURE 3 are provided with the same reference numerals with the addition of the letter b thereto. Thus, in controller 34, whenever the differential pressure through the stack 10' decreases at such a rapid rate as to indicate, for example, incipient slipping, head 45b of bellows 43b will move rapidly to the right as viewed in FIGURE 6 and operate a suitable meter to cause it to issue a corrective signal. In so moving, bellows 4312 will also swing arm 51b to the right-hand side of indicator scale Sb. A galvanometer may be in controller 34 like galvanometer 58 in which event, the pointer would move to the right of the zero position along scale 62 until, in the case of an abnormal rate of differential pressure change in a decreasing differential pressure direction, the flag of the galvanometer will move between the oscillation coils and send out a corrective signal through conductor 35 to the relay 36 for the purpose described above of operating operator 20', in series with a control action by top gas pressure controller 30" due to an abnormal rate of change in the increasing direction in the top gas pressure. As soon as a more normal pressure rate condition is restored, valve 17' will reclose and control of the differential pressure in the selected range will return to controller 25'.

Various changes in the arrangement and details of the illustrated embodiments may be made and further embodiments may be provided without departing from the spirit of my invention or the scope of the appended claims.

I claim:

1. In a control for a blast furnace or the like, in combination, a blast furnace, a gas line leading from the upper portion of said blast furnace, a blast air main leading to the lower portion of said furnace, a relief valve operatively connected to said gas line, a valve in said gas line to vary the opening therethrough, a normally closed main relief valve operatively connected to said blast main, an auxiliary relief valve operatively connected to said blast main, a differential pressure controller, means for impressing the respective pressures substantially in said blast main and gas line upon said difierential pressure controller, a signal connection between said differential pressure controller and a proportioning operator for said valve in said gas line, a signal connection between said differential pressure controller and a proportioning operator for said auxiliary relief valve, means for operating at least one of said two lastmentioned valves in response to its said signal connection 7 respectively, a top gas pressure controller, means for impressing the pressure in said gas line upon said top gas pressure controller, an on-oif operator for said main relief valve, rate of change means operatively connecting said top gas pressure controller to said main relief valve operator, said rate of change means including means for generating a magnetic signal force for said signal connections by physical movement thereof relative to a solenoid coil above a predetermined rate of change in said pressure in said gas line, magnetic response means to operate said on-ofif operator when said signal force has a predetermined magnitude corresponding to a rate above said predetermined rate, said magnetic response means being ineffective to operate said on-oif operator when the rate of change in said pressure in said gas line is below said predetermined rate, and a high limit switch in said top gas pressure controller operatively connecting the same to said operator for said main relief valve, whereby an abnormal rate of change in the pressure in said gas line above said predetermined rate or the achievement of the high limit gas pressure value in said gas line will cause said top gas pressure controller to override said differential pressure controller by the opening of said normally closed main relief valve.

2. In a control for a blast furnace or the like, in combination, a blast furnace, a differential pressure controller connected to taps transmitting respective pressures at difierent levels of said blast furnace, a gas line leading from the upper portion of said blast furnace, a blast air main leading to the lower portion of said furnace, a valve in said gas line to vary the opening therethrough, an operator for said valve in said gas line, a normally closed blast ma'in relief valve, an operator for said blast main relief valve, means for operating said first-named valve 'to regulate the pressure in said gas line, a top gas pressure controller connected-to said gas line, rate of change means operatively connecting said top gas pressure controller to said blast main relief valve operator, said rate of change means including means for generating a magnetic signal force by a movement thereof above a predetermined rate relative to an energized coil and non-contact response means for said force, said non-contact response means being ineffective to operatively connect said top gas pressure controller to said blast main relief valve operator at a rate of change below said predetermined rate, whereby an abnormal rate of change in the pressure in said gas line above said predetermined rate controller providing magnetically induced currents proportional to the rate of differential pressure change respectively at least in a decreasing direction to generate a corrective impulse, a top gas pressure rate controller responsive to the rate of change in the gas pressure adjacent the top of said stock burden, said last-named rate controller having a physically movable member providing magnetically induced currents proportional to the rates of pressure change respectively in an increasing direction to generate a corrective impulse when said member moves at a rate in excess of a predetermined rate, means for rendering said physically movable member inefiective to generate said corrective impulse at a rate of change below said predetermined rate, a sequential relay operatively connected to both said differential pressure rate controller and said top gas pressure rate controller, said relay being responsive to a leading corrective impulse issued by said top gas pressure rate controller when coupled with a following corrective impulse issued by said diflerential pressure rate controller, a relief valve connected to the bottom of said blast furnace, and an operator for said relief valve operatively connected to said relay to receive a corrective signal issued by said relay and open said valve. 7

References Cited in the file of this patent UNITED STATES PATENTS 2,178,563 Cressy Nov. 7, 1939 2,430,757 Conrad et a1. Nov. 11, 1947 2,436,639 Fans Feb. 24, 1948 2,471,776 Reece May 31, 1949 2,609,831 MacGeorge Sept. 9, 1952 2,625,386 Leone Jan. '13, 1953 2,751,576 Soergel et'al. June 19, 1956 2,814,479 Leone Nov. 26, 1957 2,816,570 Coulbourn et a1 Dec. 17, 1957

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