EA044816B1 - REDUCING GAS INPUT SYSTEM - Google Patents

Description

Field of invention

In general, the present invention relates to the field of metallurgy, and more particularly to the operation of a blast furnace, with hot reducing gas being supplied into the furnace shaft, especially into the charge area.

State of the art

With the Paris Agreement and near global agreement on the need for action on emissions, it is imperative that every industry looks at developing solutions to improve energy efficiency and reduce CO2 emissions.

In this context, iron metallurgy experts have developed new approaches to reduce the environmental footprint of the blast furnace iron production route. Indeed, despite alternative processes such as scrap smelting or direct reduction in electric arc furnaces, the blast furnace (BF) currently still represents the most widely used steel production method.

Among the approaches developed to reduce CO ₂ emissions from blast furnaces, it has been proposed to inject hot reducing gas, typically syngas (consisting primarily of CO and H2), directly into the blast furnace shaft. This is also known as shaft feed and involves introducing/feeding hot reducing gas (syngas) through the outer wall above the hot blast level (tuyeres), i.e. above the blast furnace shoulders, and preferably into the gas reduction region of the iron oxide solid phase above the sintering region.

Technical problem

It is an object of the present invention to propose a viable reducing gas injection system for supplying hot reducing gas into a blast furnace shaft, which can be implemented on existing blast furnaces. Another object of the present invention is preferably to provide a compact and cost-effective system for gas-tightly connecting a pipeline to blast furnace shaft entry points, allowing relative movement of the two systems.

General Description of the Invention

To overcome the above problem, the present invention provides, in a first aspect, a reducing gas introduction system for a blast furnace including a wall of a blast furnace, wherein the reducing gas introduction system includes:

reducing gas distribution pipe;

one or more injectors mounted on the (outer) wall of the blast furnace at shaft level;

wherein the reducing gas distribution pipe is designed to be connected to the wall of the blast furnace or its supporting structure;

wherein the one or more injectors includes an injector body with a peripheral wall extending along a longitudinal axis from a front portion with at least one nozzle opening to an opposite rear portion with an inlet port, the injector body including an internal gas passage configured to direct the reduction gas gas from the inlet pipe of the base element to the nozzle(s) hole(s);

wherein the nozzle body is secured through an opening in the wall of the blast furnace such that the front portion with the nozzle hole(s) is located on the inside of the blast furnace, while the rear portion with the inlet pipe is located outside the wall of the blast furnace, preferably this attachment is flange mounting;

wherein the injector body includes a peripheral mounting portion configured to connect the injector in a gas-tight manner to an opening in the wall of the blast furnace;

wherein the inlet pipe is in hydrodynamic communication with the distribution pipe of the reducing gas by means of an injection sleeve, and the injection sleeve includes a supply pipe connected to the distribution pipe of the reducing gas, a pipe elbow connected to the supply pipe, and an injection pipe connected to the pipe elbow, wherein the injection pipe is attached by means of a flange in a gas-tight manner to the inlet pipe of the injector, and the injection pipe and/or the outlet pipe of the pipe elbow includes at least one compensation system, which may include a universal joint.

The injection of reducing gas into a blast furnace shaft has been described in many publications, but industrial application in a commercial blast furnace has not yet been realized.

One problem when implementing shaft injection compared to the known hot blast injection at the tuyere level is the characteristics of the reducing gas. While the gas at the tuyere level is simply hot air, when introduced into the shaft the gas is a reducing gas, typically syngas containing large quantities of flammable hydrogen and CO, the latter even being poisonous to humans.

Therefore, maintaining a gas-tight connection is of paramount importance

- 1 044816 main gas distribution pipe with entry point on the blast furnace. It is particularly important to know that due to the high temperatures of the reducing gas (up to approximately 1100°C) and the high temperatures prevailing inside the blast furnace at shaft level, the blast furnace wall, reducing gas distribution pipe, injector and injection hose are subject to thermal expansion and deformation , which cause significant displacements and stresses for the entire reducing gas injection system. It is therefore necessary for the injection hose to compensate for these relative movements without the reducing gas escaping through the leak points.

In the case of tuyeres, the front of the air supply tube is pressed by a tension screw system with a spring to a tuyere built into the wall of the blast furnace. Although this provides some compensation for lateral movement, this solution is not gas-tight enough when using a reducing gas such as syngas. Therefore, in contrast to being connected to the tuyere by means of a tuyere sleeve, the injection pipe in the present reducing gas injection system is connected in a gas-tight manner to the injector by means of a flange connection. While this solves the gas-tight problem, it eliminates the ability of the elbow and injection pipe to accommodate the aforementioned relative movement.

Universal joints are known in the art of tuyere sleeves and are described, among others, in US Patents 3,662,696, 3,766,868, 4,023,832, 4,027,605, 4,987,838 and 5,462,433, which are incorporated herein by reference. Another advantage of the universal joint is described in DE 20 2012 011 622.3, which is incorporated here by reference. The tuyere sleeves of the patents mentioned herein have the advantage of allowing differential deformation during use and manufacturing inaccuracies between tubular segments of the tuyere sleeve to be compensated for, achieved through the use of universal joints, usually in connection with corrugated expansion joints having a very small number of corrugations.

However, in conventional tuyere hoses, such cardan-type compensating connections are used in the downstream portion of the tuyere hose, that is, in the part upstream of the pipe bend, and not downstream of it.

The inventors have found that the loss of flexibility caused by conventional connection via a spring tension screw fastening system in tuyere systems can preferably be balanced by placing a universal joint type compensating connection downstream of the bend of the pipe bend, for example at the exit of the pipe bend (near the location connection of the pipe elbow to the injection pipe) and/or in the injection pipe itself without any violation of the gas tightness.

In order to further compensate as much as possible for the other relative movement between the reducing gas distribution pipe and the injector(s), the supply pipe preferably also includes at least one additional universal joint. In preferred embodiments, two universal joints are provided, one near the inlet of the feed pipe and one near the outlet of the feed pipe.

Ease of maintenance and time savings during maintenance are very important, especially if there are a large number of entry points and thus connections. For this purpose, quick-release connections can be provided on the two corresponding flanges of the injection pipe, as well as on the bends of the injection pipe. In embodiments, the injection pipe is mounted via a mounting flange in a gas-tight manner using bolts or hooks on the injector inlet, the use of the hooks allowing faster assembly and disassembly. Preferably, the gas tightness is further improved by using a metal and/or soft seal between the first mounting flange on the rear of the injector body and the second mounting flange on the injection pipe. Even more preferably, all flanges of the injection hose are equipped with metal and/or soft seals. The seal can be made of different materials and have different shapes, such as flat, O-ring or others.

In addition, during maintenance, this flange mounting can also be opened to allow the connection of a drill to unlock a blocked injector on the rear flange and which will therefore, in such cases, be designed to withstand the associated forces.

Alternatively, at least for milder cases of injector clogging or simply for inspection, the pipe elbow preferably includes a window centered relative to the longitudinal axis of the injector to which is preferably removably attached a cover, a sight glass and/or a camera. The camera and the viewing glass can be used simultaneously, for example by means of a suitably placed beam splitter. Since the shaft level, as opposed to the tuyere level, is dark inside the blast furnace, the camera is preferably a thermal and/or infrared camera and/or an additional light source may be provided.

In particularly preferred embodiments, partial or increasing injector clogging can be detected by incorporating a flow sensor, or preferably a surface flow sensor or thermocouple, anywhere into the injector arm that either projects into the gas stream or is built into the refractory lining. Indeed, in the event that gas flow is severely reduced or stopped, the thermocouple temperature reading will decrease, indicating the need for inspection and maintenance.

The front region of the injector, that is, including the nozzle hole(s), can be mounted flush with the inside of the blast furnace wall, in a recess thereof, or protruding into the inside of the blast furnace. If cooling plates are mounted on the inside of the blast furnace wall, the front area of the injector can be mounted flush with the inside of the cooling plate, in its recess, or protruding into the inside of the blast furnace.

In such latter cases, the front part of the injector is configured to be mounted through a corresponding hole in the cooling plate connected to the inside of the blast furnace wall.

It should be noted that if the front region of the injector projects into the interior of the blast furnace, more than one nozzle opening may be provided in the projecting portion of the injector, the nozzle openings preferably being oriented differently, such as straight (along the longitudinal axis of the injector), downward, and /or to one of both sides perpendicularly or at any suitable angle relative to the longitudinal axis of the injector.

For protruding injectors, it may be necessary or desirable to provide a protruding cover located above the injectors and configured to protect the front portion of the injector body, which protrudes into the interior of the blast furnace, from the descending charge material.

In addition, the front part of the injector is preferably provided with a cooling system. Alternatively, a separate cooling lip may be mounted around any portion of the injector protruding into the blast furnace (in whole or in part), such that the cooling lip will not only provide thermal protection, but also wear protection. The injector and/or separate cooling lip may be cooled by (pressurized) water and may typically be made from materials such as copper, a copper alloy such as copper/nickel alloys, cast iron, cast steel, and the like.

While the injector may be manufactured from a plurality of parts, the injector comprising an injector body with a peripheral wall extending along a longitudinal axis from the front portion with at least one nozzle opening is preferably manufactured from a single piece. Thus, in embodiments, the injector will be a single piece, either protruding or not protruding into the blast furnace.

Additionally, the injector(s) may be oriented perpendicular (pointing to the center of the blast furnace) or tangential to the blast furnace wall (i.e., at any angle less than 90°, preferably greater than 10°, relative to the blast furnace wall oven at the injector location). The reducing gas injection system may include from 15 to 60 injectors, preferably from 20 to 40.

It is also important to note that the distribution pipe does not have to be a closed peripheral manifold, as is typical for a traditional ring pipe. However, this area of the shaft is usually cluttered with cold plate coolant pipes and/or support structures. Therefore, if there is not enough space in a given environment, the reducing gas distribution pipe can be divided into several parts located around the blast furnace (eg 4 quadrants), each part being supplied by separate reducing gas supply lines from the reducing gas source.

In other embodiments, where space at the tuyere level is limited, the reducing gas distribution pipe may be mounted above (or connected to) the hot blast annular duct or, preferably, to the blast furnace or its support structures, but below the level of the injectors. Therefore, the supply pipe of the injection arm is connected to the upper side of the reducing gas distribution pipe, and the injection arm is directed upward.

In consideration of the elevated temperatures of the reducing gas, the inner surface of the reducing gas distribution pipe, the injection sleeve and optionally the injector are lined with a fire-resistant insulating material to protect the reducing gas injection system.

In a second aspect, the present invention provides a blast furnace installation for producing pig iron, including a blast furnace and at least one reducing gas injection system described herein, the injector(s) being mounted at shaft level. Another advantage of the present invention is that the reducing gas distribution pipe can be mounted above or below the level of the injectors depending, for example, on the availability of sufficient space. It is even possible, in the case where the reducing gas distribution pipe is divided into several parts located around the blast furnace, to arrange some parts of the reducing gas distribution pipe above the injector level and others below the injector level.

The term hydrodynamic coupling means that two devices are connected by channels or pipes so that a fluid, such as a gas, can flow from one device to the other. This expression includes means for modifying this flow, such as valves or fans for regulating mass flow, compressors for regulating pressure, etc., as well as control elements such as sensors, actuators, etc., necessary or desirable for appropriate control of the operation of the blast furnace as a whole or the operation of each of the elements in the blast furnace installation.

The expressions at the shaft level or into the blast furnace shaft in this context implies the introduction of material above the level of the hot blast (tuyere), that is, above the shoulders, preferably into the region of gas-solid reduction of iron oxide above the region of cohesion.

Approximately in the present context means that a given digital value covers the range of values from -10 to +10% of the digital value, preferably the range from -5 to +5% of the digital value.

Brief description of drawings

Preferred embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which:

fig. 1 is a three-dimensional schematic view showing an embodiment of a reducing gas injection system into a blast furnace shaft;

fig. 2 is a partial cross-sectional view of an embodiment of an injection hose mounted between a reducing gas distribution pipe and an injector;

fig. 3 is a detailed view of another embodiment of a portion of a reducing gas injection system showing in more detail another embodiment of an elbow injector; and figs. 4 is a detailed view of yet another embodiment of part of the reducing gas injection system, showing in more detail an alternative embodiment of the elbow injector according to FIG. 3;

fig. 5 is a schematic diagram of a protective cap for an injector in A) side view and B) front view.

Other details and advantages of the present invention will be apparent from the following detailed description of several non-limiting embodiments with reference to the accompanying drawings.

Description of Preferred Embodiments

The injection of hot reducing gas into the blast furnace shaft has been mentioned in many publications, but industrial application in a commercial blast furnace has not yet been realized.

One problem when implementing shaft injection compared to the known hot blast injection at the tuyere level is the characteristics of the reducing gas. While the gas at the tuyere level is simply hot air, when introduced into the shaft the gas is a reducing gas, typically syngas containing large quantities of flammable hydrogen and CO, the latter even being poisonous to humans.

Therefore, maintaining a gas-tight connection between the main gas distribution pipe and the entry point at the blast furnace is of paramount importance.

The injector outlet may have a variety of designs ranging from simple holes, like a tuyere of holes, to injectors with more than one entry point, preferably oriented in different directions, having, for example, specific replaceable inserts, protective covers over the outlet, a cooling lip, etc.

In the area of the tuyeres, the connection between the hot gas pipe and especially between the ring pipeline and the tuyeres is realized using tuyere hoses. These tuyere sleeves primarily serve two purposes:

be a gas connection between the hot air pipe and the tuyeres built into the blast furnace shell at the tuyere level;

provide the ability to compensate for the relative movement between the tuyeres built into the blast furnace casing and the hot blast pipe connected to the independent structures of the blast furnace installation. Relative movement is relatively important due to the fact that the systems have different temperatures.

Conventional tuyere hoses consist of several parts, with the main parts being the descending part of the tuyere hose, the pipe bend and the blow pipe. The hemispherical front part of the blast tube is pressed against a tuyere built into the wall of the blast furnace using a tension screw fastening system with a spring. The tuyere sleeve elements are connected to a cardan-type compensating connection(s) into the descending portion of the tuyere sleeve, allowing movement in two directions. These two-dimensional movements are sufficient to hold the hemisphere of the blow pipe in the seat of the nose of the tuyere. This movable connection to the metal seat is sufficient when directing hot air to the blast furnace.

Conventional tuyeres themselves are also relatively complex systems consisting of a tuyere body and a tuyere nose. The latter protrudes into the blast furnace, and more specifically into the blast furnace channel. This region is characterized by very high temperature levels, typically between 2000 and 25,000°C, and very high gas velocities. Also at this level of the blast furnace there may be molten slag and iron particles, so it is obvious that the nose of the tuyere is subject to damage and must be replaced regularly.

Typically a blast furnace uses a large number of tuyeres depending on the blast furnace capacity, typically between 10 and 40.

The inventors have found that in the present reducing gas injection system, the injectors themselves can potentially be simplified compared to a lance in the tuyere area based on the following reasons:

no thick refractory lining, only a lower temperature level kiln shaft area allowing cooling using chilled plates and/or chilled box coolers and/or external water film cooling;

typical reducing gas temperature level is between 900 and 1100°C;

lower flow rate, therefore requiring a reduced pipe diameter;

lower pressure level.

One advantageous effect of this is that, due to the smaller diameter of the injector, there is more space between the injectors, which facilitates its connection by flanged bolted connections, including a metal and/or soft seal, to the blast furnace shell. Another advantage of the smaller injector diameter is that it keeps the holes in the blast furnace wall and cooling plates small. In turn, this makes it easier to retrofit this solution onto an existing blast furnace without replacing the cooling plates.

More specifically, with respect to the use of a flanged attachment of the injection hose to the injector, the gas tightness can be further controlled by applying a fixed torque when tightening the flange bolts. Typical gas tightness tests, such as soapy water, can be taken.

However, when using a flanged connection of the injector to the reducing gas distribution pipe, the injection hose must allow compensation for all relative movements of the injection hose and the reducing gas distribution pipe relative to the injector. Therefore, the present invention proposes a combination of a flange connection and a cardan-type compensating connection between the injector and the outlet of the pipe elbow.

If we return to the drawings, then in FIG. 1 is a schematic partial three-dimensional cross-sectional view of an embodiment of a reducing gas injection system 10 according to the invention for introducing a reducing gas, such as syngas, into a blast furnace shaft, the system being mounted at the level of the blast furnace shaft on a wall 30 of the blast furnace or its supporting structure (not shown). The reducing gas distribution pipe 20 of the reducing gas injection system, here covering the entire circumference of the blast furnace at the shaft level, is fed by means of a reducing gas supply line 22 and is connected to several injectors 40 with one nozzle opening 41 per injector protruding slightly into the blast furnace 31 through a corresponding opening. in cooling plate(s) 60.

The reducing gas distribution pipe 20 is connected in a gas-tight manner to the injector 40 through an injection hose including a supply pipe 51 connected to a pipe elbow 52, and a pipe elbow 52 connected to an injection pipe 53, in turn connected by a flange 535 to a corresponding flange 44 injector 40. In this embodiment, a universal joint 531 is provided in the injection pipe 53.

It should be noted that in FIG. 1-4, the supply pipe 51 is mounted on the lower side of the reducing gas distribution pipe and is directed downward, that is, the level of the injector is below the level of the reducing gas distribution pipe. However, inverted embodiments of the reducing gas injection system are also explicitly provided, wherein the level of the injector is above the level of the reducing gas distribution pipe, that is, the supply pipe is connected to the upper side of the reducing gas distribution pipe and is directed upward.

In fig. 2 shows in more detail another embodiment of the present reducing gas injection system having a reducing gas distribution pipe 20 with a fireproof lining 21 connected to the injection hose, its supply pipe 51, its pipe elbow and the injection pipe connected to the inlet pipe 43 of the injector 40. Cardan a compensating connection in this embodiment is also provided in the injection pipe 53. It should be noted that the elements of the injection pipe are also preferably provided with a fire-resistant lining,

- 5 044816 but for simplicity they are omitted from the drawings.

Preferably, the supply pipe is provided with two universal joints 511, 512 to further compensate for movements of the reducing gas distribution pipe relative to the pipe elbow 52. Preferably, all parts of the injection hose are mounted to each other using corresponding flanges, optionally equipped with suitable seals (not shown).

The injector 40 is connected in a gas-tight manner to an opening in the wall 30 of the blast furnace. If there are cooling plates (60), these cooling plates 60 are provided with corresponding openings. Preferably, the injector 40 or its nozzle body 42 includes a cooling system 45, such as cooling channels connected to the coolant circulation system, especially if the surrounding nozzle opening(s) 41 protrude from the interior of the blast furnace (31).

A maintenance and inspection hatch 521 is provided at the rear of the pipe bend, its longitudinal central axis corresponding to the central longitudinal axis of the injector 40.

Fig. 3 is a detailed view of another embodiment showing only portions of the reducing gas injection system downstream of the supply pipe (not shown). The same or equivalent features have the same numerals as mentioned above or in the list of reference numerals below.

As shown in more detail in this drawing, the injector is connected in a gas-tight manner by means of a mounting flange 40 to the wall 30 of the blast furnace.

The hatch 521 for maintenance and inspection is provided with a removable cover 524, which has a hole in its center aligned with the central longitudinal axis of the injector 40. A shut-off valve 525 with a combined inspection system with a sight glass 523 and a camera 522 is connected to the hole.

In this embodiment, a universal joint 531 is provided in the injector pipe 53.

Fig. 4 is similar to FIG. 3 except that a universal joint 531 is provided in the outlet portion of the pipe elbow 52.

In embodiments, a protruding cover may be positioned over the injector(s) and configured to protect the front portion of the injector body that protrudes into the furnace from sinking charge material. Such protection of the injector nozzle body from abrasion by means of the falling charge material (agglomerates/pellets and coke) can, for example, be achieved by means of a steel casing, smooth or corrugated. The principle of this projecting housing 100 is shown in FIG. 5 and forms a type of cover extending in the longitudinal direction L of the injector. It covers the protruding length of the injector (shown with dashed lines). As can be seen, the casing 100 is a portion of a curved steel profile, more specifically having an inverted rounded V-shape. The top 100.1 of the V-shaped profile is located above the injector 40, and two branches 100.2 extend along both sides of the injector 40, optionally even below the injector. The housing 100 may be liquid cooled, directly or indirectly. Coolant passages may be located, for example, on the lower sides of the housing.

Reference designations

10: reducing gas injection system;

20: reducing gas distribution pipe;

21: fireproof lining;

22: reducing gas supply line;

30: blast furnace wall;

31: inner side of the blast furnace;

40: injector(s);

41: nozzle(s) hole(s);

42: nozzle body;

43: inlet pipe;

44: first mounting flange (on the back of the nozzle body);

45: cooling system;

46: mounting flange (for attaching the injector to the blast furnace casing);

51: supply pipe;

511, 512: other universal joints;

52: pipe elbow;

521: hatch for maintenance and inspection;

522: camera;

523: sight glass;

524: cover;

525: valve;

-

Claims (10)

53: injector pipe; 531: universal joint; 535: another mounting flange (on the injector pipe); 60: cooling plate; 51+52+53: injection sleeve; 100: cover; 100.1: top; 100.2: two branches. CLAIM 1. A reducing gas injection system (10) for a blast furnace, including a blast furnace wall (30), the reducing gas injection system includes a reducing gas distribution pipe (20), one or more injectors (40) mounted on the wall blast furnace at shaft level, wherein a reducing gas distribution pipe (20) is connected to a wall (30) of the blast furnace or its supporting structure, wherein the injector(s) (40) include a nozzle body (42) with a peripheral wall extending along a longitudinal axis from a front portion with at least one nozzle port (41) to an opposite rear portion with an inlet port (43), the nozzle body including an internal gas passage for directing reducing gas from the inlet port (43) to the nozzle port(s) (pits) (41), wherein the nozzle body (42) is fixed through the hole in the wall (30) of the blast furnace so that the front part with the nozzle(s) hole(s) (41) is located on the inner side (31) of the blast furnace, while the rear portion with the inlet pipe (43) is located outside the blast furnace wall, the injector body (42) includes a peripheral mounting portion configured to connect the injector in a gas-tight manner to an opening in the wall of the blast furnace, wherein the injector body (43) is in hydrodynamic connection with the distribution pipe (20) of the reducing gas by means of an injection sleeve, wherein the injection sleeve includes a supply pipe (51) connected to the distribution pipe (20) of the reducing gas, a pipe elbow (52) connected to the supply pipe (51), and an injection pipe (53) connected to the pipe bend (52), wherein the injection pipe (53) is attached by means of a flange in a gas-tight manner to the inlet pipe (43) of the injector (40), and the injection pipe (53) and/or the outlet pipe of the pipe bend include at least one universal joint (531). 2. The reducing gas injection system (10) according to claim 1, wherein at least one universal joint (531) of the injection pipe (53) is connected to the pipe elbow (52). 3. The reducing gas injection system (10) according to claim 1 or 2, wherein the front region of the nozzle hole(s) protrudes from the inner side (31) of the blast furnace. 4. The reducing gas injection system (10) according to one of claims 1 to 3, wherein the supply pipe (51) includes one or more universal joints (511, 512). 5. Reducing gas injection system (10) according to one of claims 1 to 4, wherein the injector (40) is attached by means of a flange (46) in a gas-tight manner by means of bolts or hooks to an opening in the wall (30) of the blast furnace. 6. Reducing gas injection system (10) according to one of claims 1 to 5, wherein the injection pipe (53) is attached by means of flanges in a gas-tight manner by means of bolts or hooks to the inlet pipe (43) of the injector (40), preferably with metal and/or or a soft seal to provide a gas-tight seal between the first mounting flange (44) on the rear of the injector body and the second mounting flange (535) on the injector pipe (53). 7. A reducing gas injection system (10) according to one of claims 1 to 6, wherein the injector(s) (40) including an injector body (42) with a peripheral wall extending along a longitudinal axis from the front part, with at least one nozzle hole (41), made from one piece. 8. The reducing gas injection system (10) according to one of claims 1 to 7, wherein the pipe bend (52) includes a maintenance and inspection hatch (521) centrally aligned with the longitudinal axis of the injector (40), to which A cover (524), a sight glass (523) and/or a camera (522), more preferably a thermal camera or a light source camera, are preferably removably attached. 9. Reducing gas injection system (10) according to one of claims 1 to 8, wherein a gas flow sensor or, preferably, a thermocouple is mounted in the injection hose or protruding into the gas flow or built into the refractory lining of the injection hose. 10. System (10) for introducing reducing gas according to one of claims 1 to 9, wherein the front part of the injection -