Blast furnace with shaft supply of hot process gas

Abstract

The shaft furnace, particularly a blast furnace, includes a metal outer shell (14), a plurality of tuyeres (16) arranged to inject hot air into the shaft furnace, and a means for injecting process gas into the stack area of ​​the shaft. The injection device includes a nozzle body (51) having a peripheral wall (52) extending along a longitudinal axis from a front portion (54) with at least one injection hole (56) to an opposite rear portion (58) connected to a base member (60), the nozzle body (51) including an inner gas channel (62) for guiding process gas from an inlet (64) in the base member to the injection hole(s). The nozzle body (56) is attached through an opening (66) in the metal shell (14) so ​​that the front region (54) with the injection hole(s) is located inside the metal shell, while the rear portion (58) is located outside the metal shell. A base member (60) includes a peripheral mounting portion (70) configured to connect an injection device in an airtight manner to a mounting unit (68) surrounding the opening (66) in the metal shell.

Description

[Technical Field]

[0001] The present invention relates generally to the field of metallurgy, and more particularly to the operation of shaft furnaces, i.e., blast furnaces, in which hot reducing gas is fed into the furnace shaft, particularly the stack area. [Background technology]

[0002] With the Paris Agreement and near-global consensus on the need for action on emissions, it is imperative that each industrial sector considers how it can improve energy efficiency and develop solutions to reduce CO2 emissions.

[0003] In this context, actors in the field of ferrous metallurgy have developed new methods to reduce the environmental damage in the blast furnace iron-making route. Indeed, despite the existence of alternative methods such as scrap melting or direct reduction in electric arc furnaces, the blast furnace (BF) still represents the most widely used process for iron and steel production today.

[0004] Among the techniques developed to reduce CO2 emissions from blast furnaces, it has been proposed to introduce hot reducing gas, typically synthesis gas (mainly CO and H2), directly into the shaft of the blast furnace. This is also known as "shaft feeding" and refers to the introduction / feed of hot reducing gas (syngas) through the outer wall of the furnace into the ferrous oxide gas-solid reduction zone above the hot blast (tuyere) level, i.e., above the bosh and preferably above the cohesive zone. Summary of the Invention [Problem to be solved by the invention]

[0005] The object of the present invention is to improve the supply of hot reducing gas to the shaft of a blast furnace. [Means for solving the problem]

[0006] The present injection is based on the observation that the concept of shaft feeding (i.e., the introduction of high-temperature process / reducing gases into the blast furnace shaft) has been cited in many publications or patents, but has not yet been industrially applied in a commercial blast furnace. Several publications describe theoretical or experimental studies of gas injection into the shaft of a blast furnace. CFD simulations or experimental tests on small-scale models are generally used to investigate the influence of various parameters on the gas penetration and distribution in the upper part of the blast furnace, where a porous layered structure of coke and sinter / pellets is present. The conclusion of these studies is generally that the penetration depth is rather limited and that the gas remains close to the wall of the blast furnace.

[0007] The invention proposes a shaft furnace as claimed in claim 1. According to the invention, a shaft furnace, in particular a blast furnace, is a metal shell, preferably provided with cooling elements and / or refractory material, defining the outer wall of the furnace; a plurality of tuyere holes arranged around the outer wall at tuyere level for injecting hot blast into the shaft furnace; means for injecting process gas, in particular hot reducing gas, into the shaft furnace at an injection level above the tuyere level; the means for injecting process gas comprises a peripheral wall extending along a longitudinal axis from a front portion having at least one injection hole to an opposite rear portion connected to the base member; a nozzle body including an internal gas channel for guiding gas from an inlet port in the base member to the injection hole(s), the nozzle body being attached through an aperture in the metal shell such that a front region including the injection hole(s) is located inside the metal shell, while a rear region is located outside the metal shell; and a base member including a peripheral mounting portion configured to sealingly (airtightly) connect an injector to a mounting unit surrounding an opening in the metal shell, the mounting unit being located essentially outside the shell; The device includes at least one injection device including:

[0008] According to the present invention, the penetration depth of the injected process gas can be increased and adjusted by providing an injection device that projects into the furnace. The process gas is typically a hot reducing gas, e.g., synthesis gas mainly composed of CO and H2. The injection device is preferably provided to inject the hot reducing gas into the stack area of ​​the blast furnace. In practice, the injection device is connected to a hot reducing gas (e.g., synthesis gas (CO; H2)) supply outside the blast furnace via appropriate piping.

[0009] The injector device is provided with one or more injection holes (or nozzles) for hot gas outlet located in front of the nozzle body, e.g., laterally and / or at the tip of the injector. The provision of injection holes in a single injector device provides significant flexibility in terms of the direction of gas injection. Gas distribution can be increased because the injector device is not limited to a single injection point.

[0010] Additionally, the injectors themselves can be oriented either centrally or tangentially (towards the periphery of the blast furnace). A tangential orientation helps create a swirl flow within the furnace, which can enhance gas distribution and mixing with gases rising from the tuyere level. The number, size, position and angle of the injection holes in each injection device and the different combinations of the number and angle of the injection devices allow great flexibility in adapting the injection device design to specific process conditions or specific blast furnaces (small / large blast furnaces).

[0011] Another advantage of the present invention is obtained by the injection device's ability to be easily retrofitted to existing blast furnaces. The size of the injection device is advantageously selected so that it can be placed between two cooling elements (stave coolers - cast iron or copper, etc.) by core drilling midway between the outer cooling channels of two adjacent cooling elements. Alternatively, it can be installed in one stave with tailored cooling channels. By utilizing currently available rapid stave replacement technology, this type of intervention can also be achieved with a short blast furnace shutdown.

[0012] In an embodiment, an aperture in the metal shell is surrounded by a sealed mounting unit adapted to cooperate with a mounting portion of the base member. In an embodiment, the base member nozzle The nozzle body is fixed to the base member at its rear. The mounting portion surrounds the nozzle body and is hermetically coupled to the mounting unit. This allows the injection device to be gas-tightly mounted to the metal shell. Appropriate gas-tight mounting and injection device design are particularly desirable because the process gases in the intended application include CO and H2, which will spontaneously combust if leaked outside and will form an explosive atmosphere when mixed with air.

[0013] The mounting unit may include a sleeve surrounding the opening and sealingly secured to the metal shell. of A first annular flange is provided which cooperates with a second annular flange.

[0014] In an embodiment, the base member includes a cup-shaped outer element having a bottom wall surrounded by a side wall, the outer element including the second annular flange, and an inner element received inside the outer element. elementIn an embodiment, the inner element is ring-shaped and defines a central passage extending along said longitudinal axis, the central passage forming an inlet for process gas.

[0015] In an embodiment, the inner element has an outer peripheral surface including a first sealing surface, and the sidewall has an inner peripheral surface including a second sealing surface. The second sealing surface may be a conical surface tapering toward the bottom wall of the outer element, and the first sealing surface is a cooperating conical surface. Preferably, the first and second annular surfaces have matching / same cone angles.

[0016] By using an inner and outer cone, if the probe gets stuck inside the furnace due to mechanical or thermal deformation, or build-up or scaffolds, it can be easily removed. element The safety feature allows for an airtight connection between the outer element The inner part of the nozzle body can be removed separately, or if the injection device is completely deformed or has deposits on it and cannot be removed, it can be forced into the furnace. element are replaced with spare parts. This design therefore provides a safe and reliable method for removing, maintaining and replacing the injection device. For this purpose, the nozzle body and the inner element The outer dimensions of the metal shell are designed to be smaller than the cross section of the opening in the metal shell so that it can be pushed into the furnace.

[0017] The easy dismantling device is also advantageous for periodic inspection of the injection area inside the furnace during maintenance outages. Removing the injection device allows easier access for inspection and cleaning / removal of shelving around the inlet.

[0018] In a blast furnace, the injection device is usually arranged with its front engaging not only an opening in the metal shell, but also an opening in the cooling element(s) and / or refractory material covering the inner surface (or sometimes the outer surface) of the metal shell. The nozzle of the present invention is compatible with all types of cooling technologies, such as cooling panels / staves or cooling boxes and sprays. Generally, the injector is installed so that a certain length of the front of the nozzle body protrudes into the furnace interior, i.e., protruding from the front side of the metal shell and / or cooling element(s) and / or from the front side of the cooling panel or ceramic layer formed on the metal shell. The protruding length can be adjusted depending on the application and configuration of the injection holes. In some applications, such as those with axially protruding holes(s), the tip of the injector can be positioned so that it protrudes only slightly from or is flush with the front face of the cooling element / ceramic layer. This is desirable in applications where penetration depth is not the primary selection criterion and where the emphasis is on the lifespan of the injector and reduced maintenance.

[0019] In some embodiments, a protruding cover is positioned above the injector(s) and configured to protect the front of the nozzle body protruding into the furnace from descending burden material. Protection of the injector nozzle body against abrasion by such descending burden material (sinter / pellets and coke) is provided, for example, by a steel shell (smooth or corrugated), optionally water-cooled; a ceramic or refractory lining; or build-up welding made of an abrasive-resistant material. Alternatively, the upper surface of the nozzle body can be shaped to promote retention of the descending material. The injector can have, for example, a flat upper surface with upwardly facing peripheral ribs to retain the descending material.

[0020] A further possibility for protecting the protrusions of the injection device is to inject a filler material onto the injection device to form a protective mass. This can be done by means of a feed channel extending from the base member area and arranged to open into the upper front area of ​​the peripheral wall, i.e., by injecting the filler material through it after the injection device has been installed in the furnace shell. Thus, the filler material is introduced when the injection device is installed in the furnace wall and accumulates above the injection device as a protective mass.

[0021] Generally, the injection device may be equipped with instrumentation to allow for thermal, mechanical, and / or process monitoring. For example, the injection device may include one or more thermocouples for monitoring the temperature of the gas stream. It may also include wear detection sensors.

[0022] Conveniently, the components of the injection device are generally axisymmetric in shape for ease of manufacture and installation. The nozzle body and base member may typically have a circular cross section. In embodiments, particularly for the front portion of the nozzle body, an oblong or rectangular cross section may be envisaged, although it is desirable for the interface area between the nozzle body and the base member to remain axisymmetric. These and other embodiments are recited in the accompanying dependent claims 2 to 25.

[0023] The invention also relates to a process gas injection device for a shaft furnace as disclosed herein and as claimed in any one of claims 1 to 25. The injector includes a nozzle body having a peripheral wall extending along a longitudinal axis from a front portion with at least one injection hole to an opposite rear portion connected to a base member, wherein the nozzle body includes an internal gas channel for guiding process gas from an inlet in the base member to the injection hole(s). The nozzle body itself is configured to be mounted through an opening in the metal shell of a shaft furnace such that the front region with the injection hole(s) is located inside the metal shell, while the rear portion remains outside the metal shell. The base member includes a peripheral mounting portion configured to hermetically connect the injector to a mounting unit surrounding the opening (66) in the metal shell.

[0024] The present invention represents an important addition to the technology of shaft feeding and finds application, for example, in currently developed methods for the production of synthesis gas based on the reforming of hydrocarbon-containing gases (coke oven gas, natural gas) or in gas separation processes that allow the enrichment of CO and H in gas streams that are reapplied after heating in a blast furnace. The present invention allows the injection of large amounts of hot reducing gas, resulting in a significant reduction in coke consumption and CO emissions. In this regard, shaft feeding is a key technology for further increasing productivity, reducing operating costs and reducing coke consumption and CO emissions in blast furnace processes. [Brief explanation of the drawings]

[0025] The invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Figure 1] FIG. 1 is a schematic diagram of a blast furnace equipped for shaft injection of hot reducing gas. [Figure 2] 1 is a main cross-sectional view of the injection device installed in a blast furnace. FIG. [Figure 3] 1 is a schematic diagram showing a system for injecting hot reducing gas. [Figure 4] 4A) and 4B) are principal views of a protective cover for an injection device, in which FIG. 4a) is a side view and FIG. 4b) is a front view. DETAILED DESCRIPTION OF THE INVENTION

[0026] FIG. 1 shows a schematic representation of a blast furnace 10 conventionally including a hearth 12 and a shaft-forming steel shell 14 extending vertically above the hearth 12. An upper section 12.1 of the hearth wall contains tuyere 16 openings used to introduce hot blast into the furnace. In this tuyere band 12.1, the tuyere 16 are distributed circumferentially around the furnace and receive hot blast from a peripheral / annular bustle pipe 18. The shell 14 is conventionally divided into three sections: a bosh 14.1, a belly 14.2, and a stack 14.3. The blast furnace throat 20 is closed by a top cone 22 with offtakes 24 and a top ring 26. Although not shown, a top charging installation is disposed above the top cone 22 and serves to distribute the blast furnace raw materials into the furnace. The top charging installation is preferably of the BELL LESS TOP® type, and its distribution chute 28 is shown in FIG. 1.

[0027] The steel shell 14 constitutes the outer wall of the furnace. Its inner surface (i.e., facing the interior of the furnace) is generally covered with cooling panels 30 (or staves), as is more clearly seen in Figure 3. Such cooling panels typically have a slab-like body made of steel or copper (alloy) with internal coolant channels through which coolant (water) circulates. The front side of the cooling panels 30 (i.e., the side facing the interior of the furnace) is also generally covered with steel blade inserts or a protective layer of refractory material (not shown).

[0028] Reference numeral 32 in FIG. 1 denotes a shaft injection system configured to introduce hot reducing gas into the shaft of the blast furnace, i.e., above tuyere level 12.1. The hot reducing gas is typically synthesis gas containing CO and H2. Referring to FIG. 3, the shaft injection system 32 here includes multiple injectors 50 (described in detail below) connected to a first peripheral duct 36 (similar to bustle 18) that carries synthesis / process gas. In practice, the peripheral duct is therefore connected to a source of process gas (not shown). Each injector 50 is connected to duct 36 via an individual connecting pipe 38. The injectors 50 are preferably water-cooled. Reference numeral 40 denotes a second peripheral duct that carries fresh cooling water for the injectors, while cooling water discharged from the injectors is recovered via a third peripheral duct 42.

[0029] An embodiment of a fuel injection device will now be described in detail with reference to Figure 2. The injection device 50 includes a nozzle body 51 having a peripheral wall 52 extending along a longitudinal axis L from a front portion 54 with, for example, two injection holes 56, to an opposite rear portion 58 connected to a base member 60. The nozzle body 51 includes an internal gas channel 62 for directing gas from an inlet 64 in the base member 60 to the injection holes 56.

[0030] The nozzle body 51 is mounted through an opening 66 in the furnace shell 14 so that the front region 54 with the injection hole(s) is located inside the furnace, while the base portion 56 is outside the outer wall 14. The base member 60 is sealingly connected to the outer wall 14.

[0031] The shell 14 is internally lined with a cooling panel 30, so that the cooling panel (or an adjacent cooling panel) has a second opening 66' axially contiguous with the first opening 66. The injection device can therefore be conveniently positioned at the front of the furnace. The nozzle body extends through the openings in the shell 14 and the cooling panel 30 and protrudes from the cooling panel within the furnace.

[0032] The second opening 66' can be implemented within a single cooling panel or at the junction between two cooling panels where there are no internal coolant channels in the body portion. For ease of installation and sealing, a guide sleeve 67 (made from steel, ceramic material, or a suitable metal alloy) can be positioned to extend into the two openings 66, 66'. The guide sleeve 67 has an outer diameter corresponding to the diameter of the two openings 66, 66' and a length corresponding to the distance from the front side of the cooling plate to the outside of the shell 14. The inner diameter of the guide sleeve 67 matches the outer diameter of the nozzle body 51.

[0033] The opening 66 in the outer wall 14 is surrounded by a sealed mounting unit 68 adapted to cooperate with a mounting portion 70 of the base member 60. The mounting unit 68 includes a sleeve 68.1 (piping portion) that is sealingly welded to the outer surface of the surrounding shell 14 over the opening 66. The sleeve 68.1 extends generally along the axis L away from the shell 14 and has a first annular flange 68.2 surrounding its inlet that is intended to cooperate with a second annular flange 70.1 of the base member mounting portion 70. In this context, the terms "sealed" or "hermetically" refer to a gas-tight joint / assembly.

[0034] The base member 60 includes a cup-shaped outer element 72 having a bottom wall 72.1 surrounded by a side wall 72.2, and an inner element 74 received inside the outer element 72. The outer element 72 has a recess for receiving the inner element 74. nozzle The mounting portion 70 is oriented facing the main body 51. The mounting portion 70 is arranged axially continuously from the side wall 72.2 towards the mounting unit 68. It comprises a sleeve portion 70.2 welded at one end to the outer element and provided at the other end with a second annular flange 70.1.

[0035] The inner element 74 is ring-shaped and defines a central passage 74.1 extending along the longitudinal axis L, said central passage forming the inlet 64 for the process gas. The ring-shaped inner element 74 has an inner surface 74.1 and an opposite outer peripheral surface 74.2, as well as two radially extending surfaces 74.2 and 74.3, respectively. nozzleThe body 51 and the outer element have a generally conical cross section with front and rear faces 74.3, 74.4 facing towards the bottom wall 72.1.

[0036] The peripheral surface 74.2 of the inner element includes a first annular sealing surface 74.5 which cooperates with an opposing second annular sealing surface 72.3 on the inside of the side wall 72.2. In this embodiment, the first and second sealing surfaces 74.5, 72.3 are designed as cooperating conical surfaces which provide a metal-to-metal gas-tight seal. Additional sealing may be of the O-ring seal type or other metal seal. The second sealing surface 72.3 tapers towards the bottom wall 72.1, thereby reducing the inner element 74 on the outside element Pressing inwards on 72 increases the contact pressure at the sealing surfaces. Preferably, the cone angle of the first annular surface 74.5 is the same as that of the second annular surface 72.3.

[0037] Inside element 74 is the outside element 72 by a screw 76 engaged in the bottom wall 72.1 of the element It is fixed at 72. The nozzle body 51 further includes an inner tube 80 that extends axially from the base member 60 toward the front region, axially contiguous with the central passage 74.1. The inner tube 80 is configured to guide process gas from the inlet 64 to the injection holes.

[0038] As shown in FIG. 2, the intake port 64 is element The connecting duct 65 is fixed to the rear surface 74.4 of the bottom wall 72.1 and surrounds the flow path 74.1. The connecting duct 65 extends through the bottom wall 72.1 into the opening 72.4 and includes a coupler, e.g., an annular flange 65.1, for coupling to a corresponding flange 38.1 of a feed branch 38 that communicates with the peripheral pipe 36 that supplies hot reducing gas. Although not shown, the connecting duct 65 and the feed branch 38 may be provided with a refractory lining.

[0039] The nozzle body 51 and base member 60 components may generally be made from steel or a steel alloy or metal alloy. In an embodiment, the outer wall 52 and inner tube 80 may be made from copper or a copper alloy. As is clear from the figure, the peripheral wall 52 and the inner tube 80 are both element 74, the rear ends of the tubes 52 and 80 are closed (except for the injection holes) and open (as seen in FIG. 7). element 74. The inlet of the inner tube 80 surrounds the central passage 74.1 and the peripheral wall 52 surrounds the inner tube 80, forming a closed annular gap 82 between the two tubes.

[0040] This double wall construction results in injection holes 56 being formed by small tube sections 57 extending from the inner tube 80 to the peripheral wall, as shown in FIG. In this variation, the injection holes 56 are angled forward, and therefore towards the centre of the shaft. Generally, the injection holes inject the process gas in an axial ( nozzle It can be configured to inject either through an opening at the tip of the body, or laterally, either forward or downward (perpendicular to axis L) as shown, or even tangentially (i.e., along the inner shell circumference) to create a swirling effect.

[0041] Reference numeral 77 denotes a centering ring secured to the front side 74.3 of the inner ring. The dimensions (diameter / thickness) of the centering ring 77 correspond essentially to the dimensions of the guide sleeve 67. The thickness of the centering ring 77 therefore corresponds to the annular space between the outer wall and the sleeve 70.2.

[0042] The fuel injection device 50 is exposed to considerable heat in the furnace. Therefore, a thermal protection layer 84, made of, for example, a ceramic material or a steel alloy or hardfacing, is formed on the outer surface of the peripheral wall 52. An insulating layer 86, preferably ceramic or refractory, protects the inner surface of the inner tube 80. An intermediate layer of metal or insulating material may be disposed between the tube 80 and the insulating layer 86. Preferably, the copper portions (tubes 52 and 80) and the steel layers (intermediate and outer layers 84) are metallurgically bonded via a diffusion layer.

[0043] Preferably, water can be circulated in an annular gap 82 formed in the nozzle body 51. It can be foreseen that the gap 82 comprises guiding elements that avoid the formation of stagnant areas and ensure a sufficiently high water velocity, effectively protecting the injection device from the heat of the blast furnace on the one hand and from the hot synthesis gas on the other hand. Thus, a coolant inlet channel is formed in the base member 60, which includes an inlet guide passage 88 (larger than the cooling tube 96) in the side wall 72.2 of the outer element 72, and a bent passage 90 with a threaded inlet portion that runs from the first sealing surface 74.5 to an opening in the front surface 74.3 of the inner element 74 that communicates with the annular gap 82.

[0044] The coolant outlet channel includes an outlet guide channel 92 in the side wall 72.2 of the outer element 72 spaced / opposite from the inlet 88, and a curved flow path 94 with a threaded inlet leading from the first sealing face 74.5 to an opening in the front face 74.3 of the inner element 74 that communicates with the annular gap 82.

[0045] Additional sealing elements are arranged on the outer surfaces of the intake and discharge channels together with the outer wall 72.2. The first water pipe 96 is fitted into the suction guide channel 88 and extends into the curved channel 90 where it is sealingly threaded into the suction port. The first water pipe 96 includes a coupler (not shown) at its opposite end for direct or indirect connection to the peripheral duct 40. The second water pipe 98 is fitted into the suction port 92 and extends into the curved channel 94 where it is sealingly threaded into the suction port. The second water pipe 98 includes a coupler (not shown) at its opposite end for direct or indirect connection to the peripheral duct 42. The guide channels 88, 92 have a cross-section slightly larger than the outer diameter of the coolant pipes 96, 98.

[0046] Reference numeral 68.3 denotes a filling nipple through which grout, insulating material or similar material can be injected into the gap 79 (outside the furnace) between the nozzle body 51 and the sleeve 68.1, thereby reducing the risk of leakage and / or clogging with dust, etc.

[0047] In an embodiment, a protruding cover can be arranged above the injector(s) and configured to protect the front of the nozzle body protruding into the furnace from descending heavy materials. Protection of the injector nozzle body against abrasion by such descending heavy materials (sinter / pellets and coke) can be achieved, for example, by a smooth or corrugated steel shell. The principle of this protruding cover 100 is shown in FIG. 4, which forms a kind of cap extending in the longitudinal direction L of the injector. It covers the protruding length of the injector (shown by the dashed line). As can be seen from the figure, the cover 100 has a curved steel cross section, more specifically, a rounded inverted V-shape.

[0048] The apex 100.1 of the V is above the injector 50, and the two branches 100.2 extend to either side of the injector 50, and optionally even below the injector. The cover 100 can be directly or indirectly liquid cooled. Coolant channels can be arranged, for example, on the underside of the shell.

[0049] The connecting pipe 38 may include an elbow 38.1 with a rear maintenance access 38.2, the longitudinal center axis of which corresponds to the longitudinal axis L of the injection device. A cover, a view glass and / or a camera are removably attached to the inspection access 38.2. The camera and the view glass can be used simultaneously, for example by using an appropriately positioned beam splitter. As the interior of the blast furnace is dark at shaft level in contrast to tuyere level, the camera is preferably a thermal and / or infrared camera and / or may be provided with an additional light source.

Claims

1. A metal shell (14) defining the outer wall of the furnace, provided with cooling elements and / or refractory materials; a plurality of tuyere openings (16) arranged around the metal shell (14) at tuyere level for injecting hot air into the shaft furnace; means for injecting hot process gas into the shaft furnace at an injection level (14.3) above the tuyere level; said means for injecting hot process gas includes at least one injector (50); The injection device comprises:

1. A nozzle body (51) comprising a peripheral wall (52) extending along a longitudinal axis from a front portion (54) having at least one injection hole (56) therein to an opposite rear portion (58) connected to a base member (60), the nozzle body (51) including an internal gas channel (62) for directing process gas from an inlet (64) in the base member to said injection hole(s), the nozzle body (51) being attached through an opening (66) in the metal shell (14) such that a front region (54) having injection hole(s) is located inside the metal shell, while the rear region (58) is located outside the metal shell; and the base member (60) including a peripheral mounting portion (70) configured to connect the injection device in an airtight manner to a mounting unit (68) surrounding the opening (66) in the metal shell; the base member (60) is configured to support the nozzle body (51), and the peripheral mounting portion (70) surrounds the nozzle body (51) over a portion of its rear portion (58); and the mounting unit (68) includes a sleeve (68.1) surrounding the opening (66) and sealingly secured to the metal shell, the sleeve (68.1) having a first annular flange (68.2) cooperating with a second annular flange (70.1) of the peripheral mounting portion (70) of the base member (60); A shaft furnace characterized by:

2. 2. The shaft furnace according to claim 1, wherein the base member (60) comprises a cup-shaped outer element (72) having a bottom wall (72.1) surrounded by a side wall (72.2), the outer element (72) including the second annular flange (70.1), and an inner element (74) received inside the outer element (72), the inner element (74) having a first annular sealing surface (74.5) cooperating with a second annular sealing surface (72.3) of the outer element (72).

3. 3. A shaft furnace according to claim 2, wherein the inner element (74) is ring-shaped and extends along the longitudinal axis, defining a central passage (74.1) forming the inlet (64) for process gas.

4. 4. A shaft furnace according to claim 2 or 3, wherein the inner element (74) has an outer peripheral surface (74.2) including the first sealing surface (74.5), and the side wall (72.2) has an inner peripheral surface including the second sealing surface (72.3).

5. 5. A shaft furnace according to claim 4, wherein the second sealing surface (72.3) is a conical surface tapering towards the bottom wall (72.1) of the outer element, and the first sealing surface (74.5) is a cooperating conical surface.

6. 6. A shaft furnace according to claim 1, wherein the nozzle body (51) includes an inner pipe (80) extending axially from a base member to a tip, the inner pipe being configured to guide process gas from the inlet (64) to the injection holes (56) in the axially continuous central flow passage (74.1).

7. 7. The shaft furnace of claim 6, wherein a closed annular gap (82) is formed between the inner pipe (80) and the peripheral wall (52), and the base member (60) includes a coolant intake channel arranged to supply coolant fluid to the annular gap and a coolant outlet channel arranged to draw coolant fluid therefrom.

8. 8. The shaft furnace of claim 7, wherein the coolant intake channel comprises an intake guide channel (88) in the side wall of the outer element and a curved flow path (90) leading from a first sealing surface to an opening on the front side of the inner element and communicating with the annular gap (82), and the coolant discharge channel comprises an extraction guide channel (92) in the side wall of the outer element and a curved flow path (94) leading from a first sealing surface to the opening on the front side of the inner element and communicating with the annular gap (82).

9. 9. The shaft furnace of claim 8, wherein a first cooling pipe (96) is sealingly attached to the coolant intake channel and a second cooling pipe (98) is sealingly attached to the coolant outlet channel, each of the first and second cooling pipes having couplers for connection to respective coolant supply and return ducts.

10. 10. A shaft furnace according to any one of claims 1 to 9, wherein the nozzle body (51) is further inserted through the opening (66') into the cooling element or an adjacent cooling element or ceramic / refractory lining, whereby the front portion protrudes a predetermined length from the high temperature side of the cooling element, from the ceramic layer covering the front side of the cooling element, or from the ceramic / refractory lining.

11. 11. A shaft furnace according to any one of claims 1 to 10, wherein the protruding cover (100) is arranged above the injection device and is configured to protect the front of the nozzle body protruding into the furnace from descending heavy materials.

12. 12. A shaft furnace according to any one of the preceding claims, wherein the injection holes (56) are configured to allow injection of process gas along the longitudinal axis and / or transversely thereto.

13. 13. A shaft furnace according to any one of claims 1 to 12, wherein at least some of the injection holes (56) are arranged laterally in the front part (54) for injecting gas downstream or tangentially into the furnace.

14. 14. A shaft furnace according to any one of claims 1 to 13, wherein the injection device (50) is arranged through the metal shell (14) with its longitudinal axis directed towards the centre of the furnace or tangential to the inner circumference of the shell.

15. 15. A shaft furnace according to any one of claims 1 to 14, wherein the injection device comprises a process gas supply branch (65) connected at one end to the back surface of the inner element (74) and surrounding the central flow passage (74.1), the supply branch extending through an opening (72.4) in the bottom wall (72.1) and comprising a coupler at its other end.

16. 16. A shaft furnace according to claim 15, wherein the means for injecting the process gas comprises a peripheral pipe (36) surrounding the metallic shell (1), and each injector is connected to the peripheral pipe (36) by an individual supply pipe (38) connected to a coupler of each injector supply branch.

17. 17. A shaft furnace according to any one of claims 1 to 16, wherein the peripheral wall (52) is coated with an outer thermal protection layer (84) and / or the inner tube (80) is provided with an inner thermal protection layer (86).

18. 18. A shaft furnace according to any one of the preceding claims, wherein the peripheral wall (52) is covered with a wear-resistant protection of welded wear-resistant material.

19. A shaft furnace according to any one of the preceding claims, wherein the injection device (50) comprises one or more thermocouples and / or wear detectors.

20. 20. A shaft furnace as claimed in any one of claims 1 to 19, wherein the upper surface of the nozzle body (51) is flattened with upwardly directed peripheral ribs to promote stagnation of descending material by the upper surface.

21. 21. A shaft furnace according to any one of the preceding claims, wherein the injection device (50) comprises a supply channel for filling material into an opening in the front, upper region of the peripheral wall.

22. 22. A shaft furnace according to any one of claims 1 to 21, wherein the outer dimensions of the nozzle body (51) and the inner element (74) are designed to be smaller than the cross section of the opening (66) in the metal shell (14) so ​​that they can be pushed into the furnace.

23. 23. A shaft furnace according to any one of claims 1 to 22, wherein the mounting unit (68) or mounting part (70) comprises a filling nipple (68.3) for injecting grout material, insulating material into the annular space surrounding the peripheral wall (52).

24. 24. A process gas injection device for a shaft furnace according to any one of claims 1 to 23.

25. 1. A process gas injection apparatus for a shaft furnace, comprising: a nozzle body having a peripheral wall extending along a longitudinal axis from a front portion having at least one injection hole therein to an opposite rear portion connected to a base member, the nozzle body includes an inner gas channel for directing process gas from an inlet in the base member to the injection hole; The nozzle body is configured to be mounted through an opening in the metal shell of the shaft furnace, with the front region having an injection hole located inside the metal shell, while the rear region is configured to remain outside the metal shell; and the base member includes a peripheral mounting portion configured to hermetically connect the injection device to a mounting unit surrounding an opening in the metal shell; the base member (60) is configured to support the nozzle body (51), and the peripheral mounting portion (70) surrounds the nozzle body (51) over a portion of its rear portion (58); and the mounting unit (68) includes a sleeve (68.1) surrounding the opening (66) and sealingly secured to the metal shell, the sleeve (68.1) having a first annular flange (68.2) cooperating with a second annular flange (70.1) of the peripheral mounting portion (70) of the base member (60); A process gas injection system for a shaft furnace in which the process gas is injected at an injection level above the tuyere level.

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