US2879056A - System for supplying oxygen to blast furnace tuyeres - Google Patents

Description

E. R. WAGNER 2,879,056

SYSTEM FOR SUPPLYING OXYGEN T0 BLAST FURNACE TUYERES 'March 24, 195? 2 Sheets-Sheet 2 Filed Sept. 15, 1956 INVENTOR.

EL/JAH R. WAGNER, 5r. AW xffl his Attorney.

SYSTEM FOR SUPPLYING OXYGEN T BLAST FURNACE TUYERES United States Patent 0 Elijah R. Wagner, Chicago, Ill., assignor to United States Steel Corporation, a corporation of New Jersey Application September 13, 1956, Serial No. 609,703

2 Claims. (Cl. 266-29) This invention relates to a system for adding oxygen to blast furnace tuyeres at rates which are automatically proportioned to their respective rates of air supply. More I oxygen, delivered to the furnace by each tuyere is maintained substantially constant. In a manner to be described, the supply of oxygen is regulated in accordance with pressure changes in the tuyeres from furnace burden conditions which partially restrict or obstruct the tuyere blasts and thus change the rate of air flow through the tuyeres. As will be further apparent, the system of this invention is adapted for operation to supply a blast furnace with an oxygen enriched blast.

In blast furnace operations, change in the physical characteristics of the furnace burden by reason of shifting movement and other causes is frequently effective to restrict the air flow through one or more tuyeres. Reduction of air in this manner operates to slow the rate of combustion in the region of the restricted tuyere or tuyeres and may produce a localized cooling which, if permitted to continue, may result 'in one of several troublesome furnace operating problems. The primary object of this invention is to.provide a system which will avoid a reduction in the rate of combustion as a consequence of a restriction by the furnace burden to the blast from one or more tuyeres and which will be rendered effective before troublesome furnace operating problems are produced by the restriction.

Another object of the invention is to provide each tuyere of a blast furnace with an oxygen supply line and a control means for regulating the flow of oxygen therethrough to add oxygen in inverse proportion to the air being supplied by the tuyeres to the furnace. A further and incidental object is to provide for continuously adding a regulated and proportioned amountrof oxygen to the hot air blast from each tuyere, to thereby place the operation of the furnace on an oxygen enriched blast.

Another object of the invention is to provide a regulating means for controlling the addition of oxygen in accordance with the pneumatic pressure conditions in each tuyere and which will operate to increase the supply of oxygen with increases in such pressure resulting from restrictions to the blast in the furnace burden.

Other objects and advantages of the invention will become apparent from the following description.

In the drawings there is shown a preferred embodimen of the invention. In this showing:

Figure 1 is a schematic plan view which shows the application of the oxygen adding system of this invention to the tuyeres of a blast furnace and in which the blast furnace wall is shown diagrammatically in horizontal section; and H Figure 2 is a vertical sectional view taken centrally of one of the tuyeres of Figure 1 audits connection to the furnace bustle which shows the manner in which the sys-,

2,879,056 Patented Mar. 24, 1959 tem of this invention is applied to each of the blast furnace tuyeres of Figure 1.

Figure 1 illustrates diagrammatically a conventional arrangement of a bustle pipe 1 for delivering air from a hot blast main 2 to each of a plurality of blast furnace tuyeres 3. The tuyeres 3 are arranged at spaced intervals about the blast furnace hearth 4 and are respectively connected to the bustle pipe 1 by a tuyere stock 5 which extends vertically along the side (not shown) of the furnace and a goose-neck 6 as shown in Figure 2.

In accordance with the principles of this invention, each of the tuyeres 3 is provided with an apparatus for adding oxygen to the air blast which it delivers to the fur nace from the bustle pipe 1. Each such apparatus comprises an oxygen supply conduit 7 which opens into a tuyere 3 for delivering oxygen to the air moving therethrough. Each conduit 7 preferably opens into a tuyere 3 at a point 8 positioned several feet from its mouth 9 so that the added oxygen will be intimately mixed and diluted with air before delivery into the furnace. To improve mixing of the air and oxygen, a manifold (not shown) may be'provided about the tuyere for admitting the oxygen. In this respect, it will be understood that the oxygen added through the conduits 7 in accordance with the principles of this invention is in a concentrated form as distinguished from the oxygen contained in the atmosphere. It may, for example, be any commercial grade of a purity from 98%. A regulating valve 10 is provided in each conduit 7 for regulating the flow of oxygen therethrough. While a valve 10 and a regulating apparatus therefor has been shown only for one of the oxygen supply conduits 7 in Figure 1, it will be understood that a separate valve 10 and regulating apparatus of identical construction are provided for each of the conduits 7.

Regulation of the operation of each valve 10 is controlled by an Askania ratio regulator 11 which, being of conventional construction, has been shown only diagrammatically in the drawings. The regulator 11 controls the actuation of a valve operator 12 in the form of a vfluid pressure motor having a piston 13 for operating a piston rod 14 which has an actuating connection with a valve 10. The valve 10 is one which has linear operating characteristics such that the amount of oxygen supplied by the conduit 7 under its control is directly pro portional to movement of its actuating rod 14 by the motor 12. In a manner to be described, operation of the valve 10 is effected in such manner that oxygen is admitted to the tuyere 3 upon conditions occurring in the furnace 4 which restrict the blast from the tuyere 3.

The Askania ratio regulator 11 comprises a pair of double-acting fluid pressure diaphragm motors 15 and 16 which have links 17 acting in opposed relation for controlling the position of a jet-pipe 18. The jet-pipe 18 has a connection (not shown) to a source of oil supply so that it continuously delivers a stream of oil from an orifice at its upper end. The jet-pipe 18 has a pivot support 19 and bears against a fulcrum 20 which is adjustable along the length of the pipe 18 and a link 21 which has a pivotal support at 22. The position of the fulcrum 20 controls the ratio of the forces applied by the diaphragm motors 15 and 16 through the links 17 to the linkage system comprised of the jetpipe 18, the link 21, and fulcrum 20 and which is neces sary to hold the jet-pipe 18 in balanced position. When the fulcrum 20 is in a mid position directly opposite-the links 17, the motors 15 and 16 must exert equal forces of a 1:1 ratio to hold the jet-pipe 18 in a balanced position. Movement of the fulcrum 20 in opposite directions from this position of course changes this ratio and the relative force required to effect movement of the jet-pipe 18 and an actuation of the valve operating motor 12. A manual 3 control 23 is provided for adjusting the position of the fulcrum 20 along the pipe,18 and link 21. Adjustment of the position of the fulcrum 20 changes the proportional quantity of oxygen added to the tuyere blasts in a manner to be described.

Operation of the motor 12 is effected in accordance with a differential pressure applied to its piston 13 through conduits 24 connected to opposite ends of the motor 12. The conduits 24 have closely adjacent orifices 25 at their lower ends against which a stream of oil is directed from the nozzle of the jet-pipe 18 according to the conventional operation of Askania regulations. As long as the stream of oil from the jet-pipe 18 is centered with respect to the nozzle orifices 25, equal pressures will be delivered by the conduits 24 to opposite ends of the motor 12 and there will be no movement of the piston 13. When the jet-pipe 18 moves from its centered position, greater pressure will be developed in one of the conduits 24 than in the other, and a differential pressure will be developed in the motor 12 for actuating the piston 13 and piston rod 14 to regulate operation of the valve 10.

A proportional control actuation of the valve 10 is provided by a link 27 which has a pivotal connection 28 at one end to the valve actuating rod 14 and a connection at its other end to a spring 29 which has its other end connected to the diaphragm of the motor 16. The link 27 pivots about a fulcrum 30 which is vertically adjustable along its length as indicated by the arrows in Figure l to vary the proportioning action.

The operation of the diaphragm motors 15 and 16 is controlled in accordance with the pressure conditions in the valve main 2 and the tuyere stock through which air is supplied to the tuyere 3. For this purpose, the hot blast main 2 is provided with a venturi throat 31 and conduit connections 32 and 33, designated diagrammatically by broken lines, providing high and low pressure connections to opposite ends of the motor 15. In a similar manner, the tuyere stock 5 has a venturi throat 34 and is provided with high and low pressure conduits 35 and '36, respectively designated diagrammatically by broken lines, to opposite ends of the diaphragm motor 16. In this manner the differential pressures on opposite sides of the diaphragms in the motors 15 and 16 are determined respectively by the pressure and flow conditions in the hot blast main 2 and in the tuyere stacks 5.

Under normal operating conditions, the motors 15 and -16 through the links 17 hold the jet-pipe 18 in a balanced position centrally of the orifices 25 so that no movement is imparted to valve actuating rod 14. With a balanced condition of this character, the valves operate to supply oxygen to the tuyeres 3 through the supply pipes 7 according to the setting of the proportioning control fulcrum 30. This setting may be such that no oxygen is supplied to the tuyeres 3 or the position of the fulcrums 30 may be adjusted to bleed regulated quantities of oxygen into each of the tuyeres 3 to place the operation of the furnace under the action of an oxygen enriched blast.

The manner in which the diaphragm motors 16 operate to add oxygen to the air flowing through the tuyeres 3 will be best understood by considering the action which takes place when a furnace burden condition creates a partial restriction to the blast from one of the tuyeres. Such a restriction will of course decrease the flow of air through the tuyere and slow the rate of combustion in the furnace in the area opposite its mouth 9. Such partial stoppage of the flow of air will in turn change the pressure conditions in the venturi throat 34 through which the air flows to such tuyere and the pressure differential applied through the conduits 35 and 36 to the motor 16 of the valve regulator 11 for such tuyere is changed accordingly. The connections of the conduits 35 and 36 to the motor 16 are such that this causes the jet-pipe 18 to pivot in a counterclockwise direction as viewed in Figure 1 and deliver a greater quantity fluid to one of the motor conduits 24 to actuate the valve 10 in a direction to admit oxygen through the supply line 7 to the blocked tuyere. The additional oxygen acts to prevent slowing of the rate of combustion of the furnace burden opposite the affected tuyere and, when the restriction is burned away, the pressure conditions in the throat 34 will return to normal and the supply of oxygen to the affected tuyere will be cut off or returned to the rate called for by the setting of the fulcrum 30.

When the rod 14 is actuated by the motor 12 to open the valve 10 connected therewith, the link 27 pivots about its fulcrum 30 and presses against the spring 29 with a force which varies with the setting of the fulcrum 30 and which in turn presses against and thus tends to return the diaphragm in the motor 16 to its normal position. Variation of this force by adjustment of the position of the fulcrum 30 controls the amount of opening movement of the valvev 10 for a given change in the rate of air flow through the affected tuyere 3. By adjusting the position of the fulcrum 30, the valve 10 can be made to supply an amount of oxygen to the affected tuyere which, for example, is just equal to that lost by the decrease in air flow, or it can be made to supply greater or lesser amounts. While the proportioning action provided by the link 27 is desirable both for placing the furnace on an oxygen-enriched blast and for the purpose of regulating the proportional amount of make-up oxygen in the event of restriction, it will be understood that a regulator omitting this action is within the concept of this invention.

It Is also to be understood that the diaphragm motor 15 may be omitted and a regulator having a single diaphragm motor 16 responsive to pneumatic pressures in a tuyere may be employed. However, a regulator havng a motor 15 responsive to pneumatic pressures in the hot blast main 2 is desirable for the reason that it operates to compensate for changing pressure in the hot blast main and to maintain a constant supply of oxygen to the furnace. When the pressure in the main 2 drops, all of the motors 15 operate to increase the supply of oxygen through the conduits 7 to the tuyeres and, when such pressure thereafter increases, the motors 15 act to decrease the supply of oxygen. By reason of the motors 15, the regulators 11 operate to assure delivery of a constant total weight of oxygen to the furnace by compensating for change in the oxygen supplied by the hot air blast due to pressure changes in the hot blast main.

From the foregoing, it will be apparent that the regulators 11 operate by proportionally balancing the amount of oxygen delivered through each conduit 7 to the rate of flow of air through each tuyere to deliver an oxidizing blast to the furnace from each tuyere in which the oxygen content is substantially constant and is predetermined according to the desired furnace operating conditions. In this respect, attention is directed particularly to the fact that the venturis 34 continuously examine the rate of alr flow through each tuyere and through the connectlons 35 and 36 to the motors 16 effect a separate or several operation of the oxygen supply valves 10. In a similar manner, the single venturi 31 examines the rate of air flow through the main 2 and through the common connections 32 and 33 to all of the motors 15 effects a oint or simultaneous operation of the oxygen supply valves 10. The proportional operation of the valves 10 by the regulators 11 in this manner can of course be changed by adjusting the position of the fulcrum 30 to provide for the addition of a predetermined quantity of oxygen in response to a given change of air flow in either the tuyeres or hot blast main 2.

While the above description constitutes a preferred 7 example of the invention in which the regulator 11' is trol functions may be substituted and that other adaptations and modifications may be made within the scope of the following claims.

I claim:

1. In combination with a blast furnace having a plurality of tuyeres for delivering oxidizing blasts to the furnace, a bustle pipe for supplying air to said tuyeres, and a hot blast main for supplying air to said bustle pipe, a plurality of oxygen supply pipes respectively having connections with different ones of said tuyeres, separate valves for regulating the rate of flow of oxygen through said oxygen supply pipes, separate ratio regulators respectively associated with each of said tuyeres and responsive to the rate of air flow therethrough for actuating the valve in the oxygen supply pipe connected there- 15 blast main for supplying air to said bustle pipe, the combination with a tuyere having an air supply connection with said bustle pipe of a first means for measuring the rate of air flow through said main, a second means for measuring the rate of air flow through said tuyere, an oxygen supply conduit connected with said tuyere, a valve regulating the flow of oxygen through said conduit, and means responsive to both said first and second means for actuating said valve to compensate for changes in said rates of air supply and to maintain delivery of a predetermined rate of total oxygen through said tuyere.

References Cited in the file of this patent UNITED STATES PATENTS 2,051,383 Lennings et a1. Aug. 18, 1936 2,774,368 Jones Dec. 18, 1956 FOREIGN PATENTS 453,552 Great Britain Sept. 14, 1936

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