Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B7/00—Blast furnaces
  • C21B7/16—Tuyéres
  • C21B7/163—Blowpipe assembly
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B11/00—Making pig-iron other than in blast furnaces
  • C21B11/02—Making pig-iron other than in blast furnaces in low shaft furnaces or shaft furnaces
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B5/00—Making pig-iron in the blast furnace
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
  • F27B1/00—Shaft or like vertical or substantially vertical furnaces
  • F27B1/10—Details, accessories, or equipment peculiar to furnaces of these types
  • F27B1/16—Arrangements of tuyeres
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D19/00—Arrangements of controlling devices
  • F27D2019/0028—Regulation
  • F27D2019/0034—Regulation through control of a heating quantity such as fuel, oxidant or intensity of current
  • F27D2019/004—Fuel quantity
  • F27D2019/0043—Amount of air or O2 to the burner

Definitions

• the present invention relates to a process for the supersonic injection of oxygen into a melting furnace, in particular a vertical furnace, in which raw materials such as coke and scrap are charged from above and in which the combustion of combustible materials is carried out by injection of air, generally preheated, which reacts with the coke, the combustion having been initiated by means of preheating burners.
• These furnaces are in particular furnaces of the cupola type which comprise an O-ring placed at the base of the cupola in which the preheated wind is injected by heat exchange with the combustion gases, through a multitude of nozzles connected to this O-ring.
• the lances are generally dimensioned for a service pressure of Approximately 9 x 10 5 pascal (upstream of the converging / diverging device constituting the supersonic injection nozzle placed at the end of the lance).
• this pressure is only obtained at the nominal flow rate of the installation: it is only 4.5 ⁇ 10 5 pascal for operation at 60% of the nominal.
• An alternative is to operate an increasing number of lances, depending on the flow to maintain the pressure as stable as possible in the lances. This avoids low operating pressures when the oxygen flow is low. However, there is generally a dissymmetry of oxygen injection, detrimental to the proper functioning of the cupola.
• the method and the device according to the invention make it possible to avoid these disadvantages.
• the process of the invention is characterized in that the total oxygen necessary for the operation of the furnace is injected by means of two distinct circuits:
• a first circuit comprising at least one supersonic oxygen injection nozzle; a second circuit comprising complementary oxygen injection means, the second circuit being connected to the first circuit by pressure-sensitive means, such as a discharger (or more generally upstream pressure regulating means), so as to obtain a stable oxygen pressure in the first circuit as soon as the maximum flow thereof is reached.
• pressure-sensitive means such as a discharger (or more generally upstream pressure regulating means), so as to obtain a stable oxygen pressure in the first circuit as soon as the maximum flow thereof is reached.
• each nozzle there is inside each nozzle a supersonic lance whose dimensioning is provided for operation at the optimum pressure giving the maximum speed of oxygen (ie 9 bar relative to a speed of about 2.1 mach ), this pressure being reached for a fraction of the total maximum flow.
• This second circuit In the second circuit, the additional oxygen to reach the total flow is injected.
• This second circuit will inject oxygen into the cupola by a second point injection, different from the injection point of supersonic lances.
• the injection speed on this second circuit will be less, but the time of use of this second circuit will be small compared to the time of use of the first circuit.
• this second circuit will be directly powered by a "tapping" on the first circuit by means of an overflow (or a pressure regulator disposed upstream of the supersonic nozzle).
• the first circuit is dimensioned so as to obtain a supersonic injection rate of oxygen as soon as a fraction of the maximum total flow rate of oxygen, for example 60% by volume, is reached.
• the method of the invention is characterized in that the oxygen of the second circuit is injected into the wind of the cupola or concentrically around the supersonic oxygen jet, or directly into at least one of the nozzles of wind injection, preferably at a subsonic speed.
• the invention also relates to an apparatus for implementing this method, characterized in that it comprises oxygen injection means having a maximum flow rate, a first circuit comprising at least one supersonic oxygen injection nozzle a second complementary oxygen injection circuit, the first and second circuits being connected to the oxygen injection means, pressure-sensitive means, such as a discharger (or upstream pressure regulator) being interposed; between the oxygen injection means of the first circuit and the second circuit.
• oxygen injection means having a maximum flow rate
• a first circuit comprising at least one supersonic oxygen injection nozzle a second complementary oxygen injection circuit
• the first and second circuits being connected to the oxygen injection means
• pressure-sensitive means such as a discharger (or upstream pressure regulator) being interposed; between the oxygen injection means of the first circuit and the second circuit.
• the first circuit comprises a plurality of groups of at least one oxidizer injection lance, each lance group being activated successively in order to maintain a supersonic injection of oxidant in the first circuit during the increase in flow rate. oxidant of the first circuit.
• FIG. 1 a diagram of a cupola and its oxidizer supply system (hot wind) according to the prior art.
• FIG. 2 is a schematic flow diagram of oxidant injection according to the invention.
• FIG. 3 the oxidant flow curves in the various circuits.
• FIG. 4 an exemplary embodiment of FIG.
• FIG. 5 is a diagrammatic sectional view of an oxidant injection nozzle and its supersonic oxygen injection system.
• Figure 6 the oxidizer flow curves in a multi-lances system operating in stages.
• Figure 1 shows a diagram of a cupola 1 according to the prior art.
• the metal materials 5, the coke 4, etc. are introduced through the opening 2 (in successive layers) located at the top of this cupola.
• Near the top 2 is a recovery circuit 3 of the hot gases.
• the wind box 6 is supplied with 7 of preheated air in contact with fumes from 3, the wind being distributed via the pipes, such as 18 to a plurality of nozzles such as 8 and 9 at the bottom of the top furnace.
• the molten metal is recovered at 11, then 12, while the slag is recovered at 10.
• FIG. 2 represents a schematic diagram of the system according to the invention.
• the total oxygen flow rate 21 is regulated by the flow control means 22, so as to obtain an enrichment of X% oxygen (vol.) Of the hot wind of the cupola.
• the first circuit (26) corresponds to the supersonic oxygen injection circuit.
• the second circuit (27) corresponds to the low speed complementary oxygen flow circuit
• the second circuit 27 connected to the common point 28 by a discharger 23 (set for example for an upstream pressure of 9 bar) and a pipe 25.
• This second circuit makes it possible to supplement the flow of oxygen necessary for the operation of the cupola beyond the flow rate Ql.
• the circuit 26 performs the injection of oxidant supersonic lances.
• the dimensioning is intended for operation at the optimum pressure giving the maximum speed of oxygen (ie 9 bars relative to a mach speed of about 2.1).
• FIG. 3 illustrates the distribution of the flows between the first (supersonic) circuit and the second circuit.
• the hot wind cupola furnace works best when production and walking parameters are stable. Thus oxygen consumption is generally stabilized.
• Oxygen flow may be temporarily increased during restart or during a one-off increase in production, usually for fairly short periods.
• the lances are sized for maximum flow.
• the speed of oxygen is much lower than expected with the supersonic system.
• oxygen means an oxidant in general, ie usually a gas containing at least 21% vol of oxygen up to 100% pure oxygen. ).
• the speed of the oxygen injected is supersonic as soon as a significant fraction of the flow rate is reached (for example 60% of the maximum flow rate). Beyond this flow, the oxygen supplement is diverted to the second injection circuit, this second circuit being used only temporarily: the fact of having a lower speed and therefore less efficiency of this fraction of the oxygen flow rate becomes secondary to the advantage of permanently injecting 60% (case of exceptional operation) or 90 to 100% (in the case of normal operation) oxygen flow used at very high speed.
• This solution has the advantage of a simple implementation and a total transparency for the operator who can always adjust the total oxygen flow continuously.
• Curve 30 represents the flow of oxygen in the first circuit in the form of supersonic injection. This flow rate peaks around 350 Nm 3 / h corresponding to the maximum pressure reached in 21, ie approximately 9 x 10 5 pascal (curve 31 in bar with 1 bar approximately equal to 10 5 pascal). The flow rate increase (curve 32) is then performed via the circuit 2 (27).
• FIG. 3 thus defines a "normal" operating zone 33 (supersonic oxygen injection via 26) and an exceptional operating zone corresponding to the start-up of the installation, a high transient production, etc. via the circuits 26 and 27.
• FIG. 4 describes an exemplary implementation of the block diagram of FIG. 2.
• the oxidant passes successively through a filter 40, a flow meter 41, a safety valve 42, a proportional valve 43 whose output is connected to point 47 where the pipes 45 of the first circuit (26) and 46 of the second circuit (27) which supplies the discharge 44 are separated.
• Figure 5 is a sectional view of the injection nozzle 8, modified according to the invention.
• the oxygen line 16 passes through the hot wind vein coming from 14 and ends near the end of the nozzle 15 by a supersonic injection nozzle 17 (convergent / divergent).
• FIG. 6 illustrates the distribution of the flow rate between the first circuit 26 and the second circuit 27, in the case where the first circuit 26 is composed of three groups of lances with successive opening of the groups by flow rate stage.
• n groups of lances for example three groups of lances opening one after the other as explained below are used. Beyond the maximum flow rate of the first group of lances, the operation of the lances (circuit 1) in use will always be supersonic.
• the circuit 2 performs the injection of oxidizer diluted in the wind of the complementary flow A (difference between the total flow A + B and the flow of the lances in services B).
• the oxidant injection rate of this second circuit is less, but the flow fraction of this second circuit is low (15% on average).
• the circuit 2 is directly powered by a tap on the circuit 1 by means of a discharge. So the pressure in circuit 1 is stable as soon as the maximum flow rate of the first group of lances is reached.
• Non supersonic operation flow rate less than 500 Nm 3 / h: o zone 1: first group of lances and zero flow in circuit 2.
• o zone 3 the first and second groups of lances of the circuit 1 work to which is added a Ramp flow (61) in circuit 1.
• the constant flow of circuit 1 (60) and increasing of circuit 2 (61) has reached 900 Nm 3 / h, then the third group of supersonic spear is activated, the flow of the circuit 2 returns to zero and is then in the zone 4.
• o zone 4 the three groups of lances of the circuit 1 are activated with an increasing flow rate in the circuit 2.
• the curves 64 and 63 (or C and D) represent the air flow of the wind enriched respectively to 3% and 2% vol of oxygen).

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Metallurgy (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Vertical, Hearth, Or Arc Furnaces (AREA)
• Furnace Details (AREA)
• Nozzles (AREA)
• Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Gasification And Melting Of Waste (AREA)

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Publications (1)

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• 2005
  • 2005-11-10 FR FR0553430A patent/FR2893122B1/fr not_active Expired - Fee Related
• 2006
  • 2006-10-23 WO PCT/FR2006/051080 patent/WO2007057588A1/fr active Application Filing
  • 2006-10-23 BR BRPI0618504A patent/BRPI0618504B1/pt not_active IP Right Cessation
  • 2006-10-23 CN CN200680041836XA patent/CN101305104B/zh active Active
  • 2006-10-23 US US12/092,906 patent/US8317897B2/en active Active
  • 2006-10-23 RU RU2008123531/02A patent/RU2395771C2/ru active
  • 2006-10-23 EP EP06831276A patent/EP1960557A1/de not_active Ceased

Non-Patent Citations (2)

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