Tuyere stock

Abstract

The present invention relates to a tuyere stock comprising a valve adapted to control the flow of a gas having a temperature of at least 800 °C into a furnace, the valve comprising (a) a valve body having a longitudinal axis and an inner wall defining a flow path for the gas along the axis, the flow path having a cross-sectional area perpendicular to the axis; (b) a trim assembly comprising multiple shutter elements and a drive assembly adapted to reversibly displace the multiple shutter elements through the inner wall of the valve body into the flow path in the plane of the cross-sectional area, the cross-sectional area of the flow path being concentrically reduced when the multiple shutter elements are displaced into the flow path.

Description

Field of the Invention

[0001] The present invention relates to a tuyere stock comprising a valve adapted to control the flow of a gas having a temperature of at least 800 °C. Moreover, the present invention relates to a use of the tuyere stock of the present invention in a hot blast system. Furthermore, the present invention relates to a valve adapted to control the flow of a gas having a temperature of at least 800 °C. Furthermore, the present invention relates to a metallurgical installation or float glass installation equipped with a hot blast system having at least one tuyere stock according to the invention. The present invention also relates to a method of controlling the flow of a gas having a temperature of at least 800 °C. Finally, the present invention relates to a use of a valve of the present invention for controlling the flow of a high temperature gas into a furnace or in the preparation and processing of sheet glass.

[0002] A valve according to the present invention allows the control of the volume flow of a hot gas without deteriorating an inner wall defining the flow path of the hot gas adjacent to and inside of the valve, thereby providing reduced maintenance time and cost. Moreover, the valve according to the present invention may be used to control the tapping phase of a blast furnace by calming the melt during tapping.Prior Art to the Invention

[0003] A metallurgical installation such as a blast furnace operates as a continuous cycle, converting raw materials into molten metal, which is tapped periodically. A hot blast provides the heat and reducing gases while the raw materials are reduced and melted as they move through the metallurgical installation. The process is designed for efficiency, allowing the metallurgical installation to run for years without stopping, with regular tapping and recharging ensuring a smooth operation.

[0004] Introducing the hot blast into a metallurgical installation such as a blast furnace is a crucial step in maintaining the high temperatures and chemical reactions necessary for efficient production. The process requires equipment to preheat, control, and deliver the hot blast into the furnace. The system for introducing the hot blast into the furnace is an integral part of the furnace's operation and includes hot blast stoves to preheat the air to temperatures of about 900 to 1300°C, a network of hot blast mains, tuyere stocks, and tuyeres to deliver the preheated air into the furnace, as well as blowers to generate the necessary air pressure.

[0005] A schematic view of a blast furnace from the prior art is shown in Fig. 14. The blast furnace has an outer shell containing and supporting the entire system. An inner lining is provided which is made of refractory bricks to protect the outer shell from the intense heat inside. At the top of the furnace, raw materials are introduced through a charging system in alternating layers of iron ore, coke, and limestone. The stack is the largest portion of the furnace, where the iron ore descends and starts reacting with hot gases rising from below. The hearth is the lowest part of the furnace where molten iron and slag collect. The iron, being heavier, settles at the bottom, while the slag (formed from limestone and impurities) floats on top. The molten iron is periodically drained through a tap hole, while the slag is removed through a separate hole.

[0006] The blast system comprises a hot blast main being a large, insulated pipe transporting preheated air from the stoves to the furnace and connecting the hot blast stoves to the tuyere stocks. Multiple tuyere stocks branch from the hot blast main, carrying the hot air to individual tuyeres. Tuyeres are nozzles positioned at the lower part of the furnace, just above the hearth for injecting the hot blast air into the furnace at high velocity.

[0007] Accordingly, tuyere stocks connect the hot blast main to the tuyeres at the base of the furnace and are located around the circumference of the blast furnace in significant numbers of from 20 to 40 tuyere stocks per furnace. Typically made from heat-resistant alloys, tuyere stocks are insulated to prevent heat loss and to ensure that the hot air reaches the tuyeres at the desired temperature.

[0008] Tuyere stocks known from the prior art may have valves or dampers to control the flow of hot air to each tuyere and allow for adjustments in blast pressure or volume. Adjustments in blast pressure or volume are usually not necessary during the operation of a blast furnace, except for short periods of time, for example, for calming the melt or mitigating the risk of deflagration during tapping of the furnace.

[0009] Deflagration during tapping of a blast furnace is a dangerous event caused by the rapid ignition of combustible gases, often due to the sudden exposure of the furnace interior to air, contact with molten iron, or other ignition sources.

[0010] EP2547975A1 discloses a hot blast control valve comprising a metallic valve housing with a refractory lining defining a gas channel, and a valve member rotatably arranged in the gas channel for varying a free passage in the gas channel by rotating the valve member about a rotation axis between an open position and a closed position. The valve member has an envelope with rotational symmetry about the rotation axis and has a through passage arranged in the valve member in a direction transversely to the rotation axis of the valve member.

[0011] JP 09095720 discloses a butterfly valve in the feeding conduits of the hot blast to control the flow of hot blast to a furnace. The butterfly valve known from JP 09095720 comprises a disc-shaped control member mounted on a rotation axis centrally arranged in the path of the hot blast. In the closed position, the disc-shaped control member is perpendicular to the flow of hot blast and essentially blocks the path of the hot blast. The control member may then be rotated by 90° into its open position, wherein the control member is essentially parallel to the flow of hot blast, thereby allowing the hot blast to flow through the valve.

[0012] Given that the rotation axis of control members of the prior art valves is centrally arranged in the hot blast conduit, when the flow restriction of the control member in the open position is reduced to a minimum, the control member still represent an obstruction to the free flow of hot blast through the valve. Therefore, control member and refractory lining need replacement after short time, whereby maintenance time and cost are excessively high. Moreover, wear on the valve members changes the closing and sealing properties of the valve whereby the control of the valve is deteriorated over time.Disclosure of the Invention

[0013] It is the problem of the present invention to control the volume flow of a hot gas in a metallurgical installation or float glass installation for calming a melt in a furnace at reduced maintenance time and cost while any wear of the device may be accounted for during operation of the installation thereby improving safety, efficiency and efficacy of the operation.

[0014] The problem of the present invention solved according to the claims.

[0015] According to a first aspect, the present invention provides a tuyere stock comprising a valve adapted to control the flow of a gas having a temperature of at least 800 °C into a furnace, the valve comprising (a) a valve body having a longitudinal axis and an inner wall defining a flow path for the gas along the axis, the flow path having a cross-sectional area perpendicular to the axis; (b) a trim assembly comprising multiple shutter elements and a drive assembly adapted to reversibly displace the multiple shutter elements from the inner wall of the valve body into the flow path in the plane of the cross-sectional area, the cross-sectional area of the flow path being concentrically reduced when the multiple shutter elements are displaced into the flow path.

[0016] According to a second aspect, the present invention provides a use of a tuyere stock as defined in the first aspect in a hot blast system of a furnace selected from a blast furnace, a Cupola furnace, a basic oxygen furnace, an electric arc furnace, a smelting furnace for non-ferrous metals, and a blast oxygen furnace for copper smelting.

[0017] According to a third aspect, the present invention provides a valve adapted to control the flow of a gas having a temperature of at least 800 °C into a furnace, the valve comprising (a) a valve body having a longitudinal axis and an inner wall defining a flow path for the gas along the axis, the flow path having a cross-sectional area perpendicular to the axis; (b) a trim assembly comprising multiple shutter elements displaceable from the inner wall of the wall body into the flow path in the plane of the cross-sectional area, the cross-sectional area of the flow path being concentrically reduced when the multiple shutter elements are displaced into the flow path.

[0018] According to a fourth aspect, the present invention provides a furnace equipped with a hot blast system having at least one tuyere stock according to the first aspect or a valve according to the third aspect.

[0019] According to a fifth aspect, the present invention provides a method of controlling the flow of a gas having a temperature of at least 800 °C into a furnace, the method comprising the following steps: (i) providing a furnace equipped with a hot blast system having at least one tuyere stock according to the first aspect or a valve according to the third aspect; (ii) concentrically reducing the cross-sectional area of the flow path of the gas by displacing the multiple shutter elements from the inner wall of the wall body into the flow path of the gas, or concentrically increasing the cross-sectional area of the flow path of the gas by displacing the multiple shutter elements out of the flow path of the gas.

[0020] According to a fifth aspect, the present invention provides a use of a valve as defined in the third aspect for controlling the flow of a high temperature gas into a furnace or in the preparation and processing of sheet glass.

[0021] The present invention is based on the recognition that control the volume flow of a hot gas in a metallurgical installation or float glass installation may be accomplished by a tuyere stock having a specific valve containing multiple shutter elements which are adapted to avoid any obstruction of the flow of the hot gas when the valve is completely open, and which shutter elements cooperate when the valve is closing so as to maintain the maximum velocity of the flow of hot gas along the longitudinal axis of the valve in the center of the flow path. Accordingly, the valve may be used for calming a melt in a furnace during tapping in an efficient and effective manner at reduced maintenance time and cost while any wear of the valve may be accounted for during operation of the installation.

[0022] The valve according to the present invention may be designed to cover only a limited length of the flow path of the hot blast so that the valve may be used in any tuyere stock geometries. Furthermore, in the event of a valve failure, it is possible to quickly remove the valve from the tuyere stock and continue operation with a temporary dummy. Moreover, the valve of the present invention does not require any additional cooling, for example water cooling, during operation.Brief Description of the Figures

[0023] Fig. 1 shows a perspective side view of an embodiment of the valve according to the present invention. Fig. 2 shows a front view of the embodiment of the valve according to the present invention shown in Fig. 1. Fig. 3 shows a cross-sectional view across the plane A-A shown in Fig. 2. Fig. 4 shows a side view of the embodiment of the valve according to the present invention as shown in Fig. 1. Fig. 5 shows a cross-sectional view of the plane B-B shown in Fig. 4. Fig. 6 shows a cross-sectional view of the plane C-C shown in Fig. 4. Fig. 7 shows a top view of the embodiment of the valve according to the present invention as shown in Fig. 1. Fig. 8 shows a cross-sectional view of the plane D-D shown in Fig. 7. Fig. 9a and Fig 9b show a perspective top view and a perspective bottom view, respectively, of a shutter element for an embodiment of a valve according to the present invention. Fig. 10 shows a partial view of a tuyere stock of the present invention with a valve positioned at a preferred position. Fig. 11 shows a housing of a valve body of an embodiment of the valve of the present invention. Fig. 12 shows a rotor element contained in the housing of a valve body shown in Fig. 11, which serves as a bearing for rotating components and as a drive for the shutter elements. Fig. 13 shows a worm shaft forming part of a worm drive of a valve according to the present invention. Fig. 14 shows a perspective schematic view of a conventional blast furnace equipped with a blast system known from the prior art. Fig. 15 shows a perspective view of a conventional tuyere stock known from the prior art. Detailed Description of the Invention

[0024] According to the first aspect, the present invention provides a tuyere stock. The tuyere stock may be based on a conventional tuyere stock design known from the prior art which is shown in Fig. 15.

[0025] The tuyere stock comprises a downleg upper part b, a downleg lower part c, an elbow d, and a blowpipe e which is designed to optimize the flow of hot air while accommodating the furnace layout. Downleg upper part b and downleg lower part c may be combined into a joint compensator.

[0026] The downleg upper part b is a section of the tuyere stock mounted at the hot blast main and arranged substantially in the vertical direction for directing the flow of preheated air downward, starting the pathway from the main hot blast pipeline toward the tuyere of the furnace. In a particular design, the downleg upper part b may comprise a constriction of the flow path such as a Venturi (not shown).

[0027] The downleg lower part c is mounted as an extension at the distal end of the downleg upper part b. Similar to the downleg upper part b, the downleg lower part c directs the air substantially vertically to bring it closer to the tuyere.

[0028] The elbow d is provided downstream from the downleg lower part c for redirecting the airflow in a substantially horizontal direction into the blowpipe e. The elbow d allows the air to turn and align with the tuyere system while maintaining flow efficiency and minimizing turbulence.

[0029] The blowpipe e is a short, straight pipe connected to the elbow, leading directly into the tuyere of the furnace. The blowpipe e injects the hot air into the tuyere, which then delivers it to the furnace for combustion and smelting processes. The blowpipe e provides the final conduit through which the hot blast is precisely delivered into the tuyere, ensuring that the air reaches the furnace's combustion zone efficiently. The diameter of the output orifice of the blowpipe is preferably in the range of 80 to 180 mm, more preferably 100 to 150 mm.

[0030] The tuyere stock, including the downleg upper part b, the downleg lower part c, the elbow d, and the blowpipe e, is typically made of heat-resistant materials (e.g., high-strength alloys) to withstand the extreme temperatures and pressure of the hot blast. Moreover, the entire tuyere stock system, including the downleg upper part b, the downleg lower part c, the elbow d, and the blowpipe e, is thermally insulated by a refractory a. The refractory a is necessary to maintain the high temperature of the hot blast of typically between 900°C and 1,200°C as it travels through the tuyere stock. Accordingly, the refractory a prevents heat loss, ensuring that the air delivered to the furnace maintains the desired high temperature for optimal combustion. Moreover, the refractory a protects the tuyere stock components from the extreme heat, extending their operational life and preventing overheating. Finally, by minimizing heat loss, the refractory a reduces energy consumption, as less fuel is required to maintain the air at the required temperature. The refractory a is often made from refractory materials or ceramic fibers. According to a preferred embodiment, an additional thermal insulation is provided between the inner wall of the downleg upper part b, the downleg lower part c, the elbow d, the blowpipe e, and the surface of the standard refractory opposite to the surface exposed to the hot blast as disclosed in EP2354257.

[0031] A tuyere stock of the present invention may comprise a Venturi for controlling the flow by causing a pressure drop and an increase in velocity as the fluid passes through a constricted section. The Venturi may have a constriction with a diameter of from 100 to 250 mm, more preferably 130 to 200 mm. Preferably, the diameter of the constriction in the Venturi is larger than the diameter of the output orifice of the blowpipe.

[0032] Preferably, the flow velocity of the hot gas in the Venturi is in the range of 50 to 400 m / s. For example, when the diameter of the Venturi is in the range of 150 to 170 mm, the flow velocity of the hot gas in the Venturi is in the range of 110 to 150 m / s.

[0033] According to a preferred embodiment, radial bores are provided upstream and downstream of the constriction of the Venturi for measuring a pressure drop caused by the Venturi.

[0034] The pressure drop may be used to measure the flow rate of the hot air. By monitoring the pressure before and after the Venturi, the velocity and flow rate may be calculated. Preferably, the Venturi is positioned upstream from the elbow d, for example between the downleg upper part b and the downleg lower part c.

[0035] According to the present invention a tuyere stock comprises a valve adapted to control the flow of a gas having a temperature of at least 800 °C into a furnace.

[0036] The valve may be positioned in the tuyere stock of the present invention generally at any position in the downleg upper part b, the downleg lower part c, the elbow d, and the blowpipe e. However, it is preferred that the valve is positioned in or adjacent to the downleg upper part b or the downleg lower part c.

[0037] According to a particular embodiment wherein a Venturi is used, the valve is positioned in the direction of flow immediately downstream from the Venturi in the assembly of the joint compensator as shown in Fig. 15. Accordingly, the velocity of the flow of hot gas in the valve of the present invention may be controlled in the range of 50 to 400 m / s. For example, at a diameter of the Venturi in the range of 130 to 190 mm, when the valve in the fully open position and the diameter is in the range of 210 to 230 mm, the flow velocity of the hot gas in the valve is in the range of 80 to 120 m / s. Also, at a diameter of the Venturi in the range of 130 to 190 mm, when the valve is closed to 30 percent of the cross-sectional area of the flow path so that the diameter is in the range of 63 to 69 mm, the flow velocity of the hot gas in the valve is in the range of 220 to 320 m / s. Preferably, the diameter of the constriction in the Venturi is smaller than the diameter of the valve in the fully open position.

[0038] According to another preferred embodiment, the inner wall of the valve is adapted to provide a constriction even when the valve is fully open.

[0039] According to a preferred embodiment, the valve is mounted in the tuyere stock by means of detachable flange connections. In this embodiment, the valve is installed within the tuyere stock, and detachable flange connections are used to secure the valve in place. Flange connections consist of circular rims with bolt holes, allowing the valve to be securely attached to the tuyere stock. The flanges on the part of the valve are preferably integrated into the valve body by welding. On the part of the tuyere stock, these flanges are typically welded or bolted to the ends of pipes of the tuyere stock, and the valve is mounted between the flanges using bolts. The detachable nature of the flanges means the valve can easily be removed or replaced for maintenance, inspection, or repair without disrupting the entire tuyere system or requiring extensive disassembly. This method of connection ensures a reliable seal to handle the high-pressure, and high-temperature conditions present in the tuyere stock, while also offering flexibility and ease of maintenance. By using detachable flange connections, downtime during maintenance can be minimized, improving operational efficiency. According to a preferred embodiment, radial bores are provided in the upstream flange and the downstream flange, respectively, for measuring a pressure difference.

[0040] According to the present invention, the overall length of the valve portion mounted in the tuyere stock and thereby the length of the flow path provided by the valve of the present invention, is in the range of from 300 to 800 mm, more preferably 400 to 600 mm, and in particular 450 to 550 mm or less than 500 mm.

[0041] The valve according to the present invention comprises a valve body having a longitudinal axis and an inner wall defining a flow path for the gas along the axis, the flow path having a cross-sectional area perpendicular to the axis. The flow path is preferably defined by one or more refractory elements having one or more inner walls forming a stationary and sealed conduit with a circumferential gap accommodating movable shutter elements actuated by a rotor element rotating around the longitudinal axis of the valve. The inner wall of the valve defines the boundaries of the flow path, which guides the gas through the valve along this axis. Preferably, the inner wall of the valve body comprises a refractory material capable of maintaining structural integrity and thermal stability at elevated temperatures.

[0042] Therefore, the refractory materials capable of maintaining their structural integrity and thermal stability at elevated temperatures is preferably a refractory concrete of the following composition (calculated as oxides): SiOz35 to 45 % preferably about 40 % Al 2 O 3 47 to 57 % preferably about 52 % Fe 2 O 3 0.6 to 1.7% preferably about 1.1 % CaO3.0 to 4.0% preferably about 3.5 %

[0043] A suitable refractory concrete is commercially available as Gopelit 155 / m (VGT-DYKO GmbH, Grossalmerode / Germany).

[0044] The valve body preferably comprises a welded metal housing. The material of the housing is preferably selected from heat-resistant steel such as 1.0425 steel or 1.7225 (42CrMo4) steels.

[0045] The housing may be adapted to receive a rotor element for actuating the shutter elements of the valve. Moreover, the housing comprises refractory components forming the inner walls of the valve body. Specifically, the housing may contain one or more refractory sleeves providing heat resisting inner walls of the valve. The refractory sleeves may be seated in heat insulating components for reducing the heat flow toward the metal housing. Preferably, the refractory sleeves are made of a refractory ceramic material. Adjacent refractory sleeves may be provided in a spaced-apart relationship so that the shutter elements may be provided in the space between the refractory sleeves and displaced into the flow path of the hot gas. Preferably, the spaced-apart refractory sleeves and the shutter elements provided between the refractory sleeves form a seal which prevents any hot gas from escaping the flow path. Moreover, adjacent refractory sleeves which are not accommodating shutter elements, may be provided in a spaced-apart relationship so that heat insulating and sealing members may be provided in the space between the refractory sleeves.

[0046] According to a further preferred embodiment, the valve body comprises a welded metal housing having two welded flange portions wherein two outer refractory sleeves are received inside the flange portions for sandwiching an inner refractory sleeve received in a rotor element. On the downstream side of the inner refractory sleeve, the adjacent outer refractory sleeve is provided in a spaced-apart relationship so that the shutter elements may be accommodated. On the upstream side of the inner refractory sleeve, the adjacent outer refractory sleeve may be provided in a spaced-apart relationship so that a heat insulating sealing member may be accommodated.

[0047] The inner wall of the inner refractory sleeve may be provided with a constant diameter. Alternatively, the inner wall of the inner refractory sleeve may be provided with an increasing diameter in the flow direction. Also, a portion of the inner wall of the inner refractory sleeve may be provided with a constant diameter and an adjacent portion of the inner wall of the inner refractory sleeve may be provided with an increasing diameter in the flow direction. The inner wall of the outer refractory sleeves is preferably provided with a constant diameter.

[0048] In general, the valve body has a longitudinal axis, which serves as the central line along which the gas flows. When the valve body comprises refractory sleeves, the longitudinal axis of the valve body coincides with the longitudinal axis of the refractory sleeves. At the same time, the longitudinal axis also indicates the center of the valve body where the velocity of the gas flow is kept at its maximum throughout the operation of the valve.

[0049] The cross-sectional area, measured perpendicular to the longitudinal axis, represents the size of the opening through which the gas flows and influences the flow rate. By adjusting the cross-sectional area through opening or closing the valve, the valve controls the volume of gas flowing through the tuyere stock as well as the velocity of the flow of gas. Preferably, the cross-sectional area is circular when the valve is fully open. Alternatively, the valve may have a cross-sectional area with a shape of a polygon. The diameter of the cross-sectional area of the valve is in the range of 300 to 800 mm, more preferably 400 to 600 mm, and in particular 450 to 550 mm.

[0050] Moreover, the valve comprises a trim assembly comprising multiple shutter elements. The material of the shutter elements is not particularly limited as long as the material is capable of withstanding temperatures in the range of 800 to 1300°C and exhibiting a limited coefficient of thermal expansion. Therefore, the shutter elements comprise one or more refractory materials capable of maintaining their structural integrity and thermal stability at elevated temperatures. For example, the shutter elements may comprise a material selected from ceramics, refractory metals, high temperature alloys and refractory concrete. Examples of ceramics include silicon carbide, alumina, zirconia and mullite ceramics. Examples of refractory metals may be selected from tungsten and molybdenum. Examples of high temperature alloys may be selected from Inconel (nickel-chromium alloys) and Haynes alloys. A refractory concrete may have the following composition (calculated as oxides): SiOz35 to 45 % preferably about 40 % Al 2 O 3 47 to 57 % preferably about 52 % Fe 2 O 3 0.6 to 1.7% preferably about 1.1 % CaO3.0 to 4.0% preferably about 3.5 %

[0051] A suitable refractory concrete is commercially available as Gopelit 155 / m (VGT-DYKO GmbH, Grossalmerode / Germany).

[0052] Preferably, the thickness of the shutter elements is in the range of 20 mm to 40 mm, more preferably 25 to 35 mm.

[0053] The shutter elements are movable components that enter and exit the flow path, allowing for precise regulation of the flow of the hot gas. When the shutter elements are displaced into the flow path, they partially obstruct the area through which the fluid passes. According to a preferred embodiment, the shutter elements are adapted to reduce the cross-sectional area of the flow path to at most 30 percent of the cross-sectional area, whereby when the valve is in its most restricted position, the available area for the hot gas to flow through is reduced to 30 percent or more of the fully open area. This reduced area means that the flow of the hot gas will be limited, decreasing the total volume of gas that can flow in a given time period. According to the continuity equation which states that the flow rate in a steady flow system is constant, if the cross-sectional area is reduced while maintaining a constant flow rate, the velocity of the gas will increase. As the flow path is reduced to 30 percent, the gas will be forced to move faster through the smaller opening to maintain the same mass flow rate. An increase in velocity can lead to different flow characteristics, such as turbulence or higher energy in the flow. On the other hand, the reduction of the cross-sectional area may be controlled with the valve of the present invention so as to maintain an essentially laminar flow or to introduce turbulence. Moreover, as the cross-sectional area decreases, the pressure of the gas downstream of the restriction is reduced. The greater the reduction in the cross-sectional area, the higher the pressure drop. Accordingly, the valve may be used to manage pressure changes or regulate flow velocity of the hot gas. The management of pressure changes and flow velocity allows controlling a tapping phase, for example, of a blast furnace by calming the melt during tapping

[0054] Moreover, the valve may also be used to control the thermal properties of the hot gas. Specifically, at higher velocities, friction with the valve's walls or internal components may cause heating. Additionally, rapid changes in pressure and velocity can impact the system's overall thermal management. Mechanical wear can also increase because the high-speed flow of hot gas, especially if containing particulates, can cause erosion of the valve's internal components over time. However, according to the present invention, any erosion or wear of the internal components of the valve may be accounted for by the trim assembly.

[0055] The trim assembly of the valve further comprises a drive assembly adapted to reversibly displace the multiple shutter elements from the inner wall of the valve body into the flow path in the plane of the cross-sectional area. The drive assembly, which powers the movement of the shutter elements, is designed to reversibly displace the shutter elements. Accordingly, the shutter elements can move both into and out of the flow path, depending on the desired flow control. The drive assembly may be operated by various mechanisms, such as manually, electric, pneumatic, or hydraulic actuators, offering smooth and controlled movement of the shutters. Preferably, the drive is an electric drive with the option for manual operation in emergency situations.

[0056] According to a preferred embodiment, the housing of the valve body contains a rotor element having a worm gear which may be actuated by a worm shaft. The housing acts as a stator wherein the rotor element is mounted. The housing and the rotor element are adapted to receive and movably hold the shutter elements so that the shutter elements may be displaced into the flow path when the rotor element is actuated. According to a preferred embodiment, six ceramic shutter elements in the form of lamellae are used, which are driven by a rotor (worm gear) and guided via the stator in the housing.

[0057] According to the present invention, the cross-sectional area of the flow path is concentrically reduced when the multiple shutter elements are displaced into the flow path. Moreover, the cross-sectional area of the flow path is preferably concentrically increased when the multiple shutter elements are displaced out of the flow path.

[0058] According to the invention, the drive assembly is preferably adapted to synchronously displace the shutter elements of the valve. In this configuration, the drive assembly moves the shutter elements in a coordinated manner, ensuring that all the shutters are displaced simultaneously and uniformly. This synchronous displacement ensures that each shutter element moves together, either opening or closing the valve in perfect alignment. By moving the shutters in sync, the drive assembly ensures consistent flow control and prevents imbalances in the flow path that could lead to turbulence, pressure variations, or inefficiencies.

[0059] According to a preferred embodiment, the drive is a rotary actuator with torque output.

[0060] According to a preferred embodiment, the highest velocity of the gas flow may be maintained at the center of the cross-sectional area when the shutter elements of the valve are displaced into the flow path. When the valve's shutter elements move into the flow path, the available area for the gas to flow through is reduced, thereby effectively regulating the flow. In this embodiment, the shutter elements are positioned along the outer edges of the flow path, leaving the center of the cross-sectional area unobstructed. Accordingly, the gas flows most rapidly in the central part of the valve where no shutter elements are present. Accordingly, the central part of the flow path experiences less turbulence and resistance, allowing the gas to move smoothly through the valve. By focusing the gas velocity at the center, the design minimizes pressure drops and ensures efficient flow regulation even when the valve is partially closed. This is particularly beneficial in high-flow applications where it is essential to maintain consistent performance despite the partial obstruction caused by the shutter elements. It balances flow control while preserving flow efficiency.

[0061] According to a preferred embodiment of the present invention, the shutter elements of the valve do not obstruct the flow path when the valve is fully open. According to the present invention, when the valve is fully open, the shutter elements are preferably positioned completely outside the flow path defined by adjacent refractory elements, ensuring that there is no interference with the fluid or gas moving through the valve. This is relevant because, in the fully open position, the valve is intended to allow maximum unobstructed flow. If the shutter elements were to partially obstruct the flow path, it could cause a reduction in the flow rate, create turbulence, or increase pressure losses, erosion and wear, which would negatively impact the system's efficiency. By ensuring that the shutter elements are out of the flow path when open, the design provides unobstructed flow, allowing the fluid to move freely through the valve with minimal resistance.

[0062] Preferably, the shape of the cross-section of the flow path obstruction defined by the shutter elements is a polygon, such as a regular polygon, notably selected from a hexagon, octagon, decagon, dodecagon, tetradecagon, hexadecagon, octadecagon, and icosagon. According to a particularly preferred embodiment, the shape is a hexagon.

[0063] According to a preferred embodiment, the shutter elements are adapted to slidingly engage adjacent shutter elements in a sealing manner. For this purpose, a shutter element is provided with a convex edge engaging a corresponding concave edge of an adjacent shutter element. Preferably, the outer contours of the portion of the multiple shutter elements displaced from the inner wall into the flow path are preferably the same.

[0064] According to the second aspect, the present invention provides a use of a tuyere stock of the invention in a hot blast system of a furnace selected from a blast furnace, a Cupola furnace, a basic oxygen furnace, an electric arc furnace, a smelting furnace for non-ferrous metals, and a blast oxygen furnace for copper smelting. Most preferably, the furnace is a blast furnace.

[0065] According to the third aspect, the present invention provides valve adapted to control the flow of a gas having a temperature of at least 800 °C into a furnace, the valve comprising (a) a valve body having a longitudinal axis and an inner wall defining a flow path for the gas along the axis, the flow path having a cross-sectional area perpendicular to the axis; (b) a trim assembly comprising multiple shutter elements displaceable from the inner wall of the wall body into the flow path in the plane of the cross-sectional area, the cross-sectional area of the flow path being concentrically reduced when the multiple shutter elements are displaced into the flow path.

[0066] According to the fourth aspect, the present invention provides a metallurgical installation or float glass installation equipped with a hot blast system having at least one tuyere stock or a valve according to the present invention.

[0067] According to the fifth aspect, the present invention provides a method of controlling the flow of a gas having a temperature of at least 800 °C into a furnace, the method comprising the following steps: (i) providing a furnace equipped with a hot blast system having at least one tuyere stock according to any of claims 1 to 10 or a valve according to claim 11; (ii) concentrically reducing the cross-sectional area of the flow path of the gas by displacing the multiple shutter elements through the inner wall of the wall body into the flow path of the gas, or concentrically increasing the cross-sectional area of the flow path of the gas by displacing the multiple shutter elements out of the flow path of the gas.

[0068] According to the sixth aspect, the present invention provides a use of a valve of the present invention for controlling the flow of a high temperature gas into a furnace or in the preparation and processing of sheet glass.

[0069] The present invention will now be explained in further detail with reference to the figures.

[0070] Fig. 1 shows a perspective view of an embodiment of the valve 1 according to the present invention. The valve 1 comprises a valve body 10. The valve body comprises a housing 100 shown in further detail in Fig. 11 for an embodiment with 12 shutter elements. The housing comprises flanges 104, 106 for detachably connecting the valve in a tuyere stock assembly. The housing 100 also comprises a tubular portion 108 accommodating a worm shaft 110 shown in further detail in Fig. 13, for driving the shutter elements 120 through a rotor element 200 shown in further detail in Fig. 12 for an embodiment with twelve shutter elements 120. The housing 100 of the valve body functions as a stator and abutment for the shutter elements 120 during actuation of the shutter elements 120.

[0071] The valve body 10 has a longitudinal axis A.

[0072] Moreover, the valve body 10 has an inner wall 102 defining a flow path for the gas along the axis A. In Fig. 1, the inner wall is defined by an outer refractory sleeve 132b and an inner refractory sleeve 130. The flow path has a cross-sectional area perpendicular to the longitudinal axis A.

[0073] Furthermore, the valve 1 comprises a trim assembly 12. The trim assembly comprises multiple shutter elements 120. The shutter elements are displaceable from the inner wall 102 of the wall body 10 into the flow path in the plane of the cross-sectional area by the trim assembly by actuating a rotor element 200 having a worm gear 210 with a worm shaft 110, whereby the rotational movement translates into a linear displacement of the shutter elements 120 seated in linear guide grooves 101 of the housing 100 and driver grooves 222 of the rotor element each engaging corresponding protrusions 121, 122 of the shutter elements.

[0074] Fig. 2 shows a front view along the longitudinal axis A of the embodiment of the valve according to the present invention shown in Fig. 1. As shown, the housing 100 comprises a flange 106 welded to the valve body. Moreover, a tubular portion 108 accommodates a worm shaft 110 forming part of the trim assembly of the valve 1.

[0075] Fig. 3 shows a cross-sectional view of the plane A-A shown in Fig. 2. In Fig. 3, the inner wall 102 of the valve body 100 is shown, which is defined by ceramic sleeves 130, 132, 134. A journal bearing bushing 140 is provided for supporting the rotor element 200 and keeping it aligned. The rotor element 200 rotates inside the bushing, which is fixed in place, allowing for rotational movement without excessive wear on either component.

[0076] Fig. 4 is a side view of the embodiment of the valve according to the present invention as shown in Fig. 1. A housing 100 comprising an upstream flange 106 and a downstream flange 104 is provided with a worm shaft 110 driven by an electric drive 300 or a manual drive 301. Radial bores 105, 107 are provided for measuring a pressure drop across the valve 1.

[0077] Fig. 5 shows a cross-sectional view of the plane B-B shown in Fig. 4. A housing 100 accommodating a worm shaft 110 driven by electric drive 300, as well as a rotor element 200 having a worm gear, contain refractory elements defining a flow path for the hot gas.

[0078] Fig. 6 shows a cross-sectional view of the plane C-C shown in Fig. 4. Accordingy, outer refractory sleeves 132, 134 and inner refractory sleeve 130 form the inner wall defining a flow path for the hot gas. As shown, the shutter elements a completely removed from the flow path. Rotor element 200 is movably received in the housing element 200 and contains the inner refractory sleeve 130. When the rotor element 200 is actuated, the shutter elements are displaced into the flow path of the hot gas.

[0079] Fig. 7 shows a top view of the embodiment of the valve 1 according to the present invention as shown in Fig. 1. In Fig 7, an electric drive 300 is shown which drives worm shaft 110 for displacing the shutter elements by actuating the rotor element. The valve may be mounted in a tuyere stock with flanges 104, 106.

[0080] Fig. 8 shows a cross-sectional view of the plane D-D shown in Fig. 7. As shown in Fig. 8, six shutter elements 120 are centrosymmetrically arranged around a central point coinciding with the longitudinal axis A of the valve1 and forming a hexagonal aperture. When the shutter elements move inward, they symmetrically close off the aperture by converging on the center. This symmetry ensures uniform control of the fluid or gas flowing through the valve, without causing imbalances or turbulence in the flow.

[0081] Fig. 9a and Fig 9b show a perspective top view and a perspective bottom view, respectively, of a shutter element 120 for an embodiment of a valve according to the present invention. Specifically, the shutter element has an essentially trigonal shape with a leading edge 123 forming an angle 125 with sealing edge 124. Leading edge 123 is displaced into the flow path and forms a polygonal orifice when obstructing the flow of the hot gas. Leading edge 123 is provided with a convex cross-section for slidably engaging a corresponding concave sealing edge 124 of an adjacent shutter element. A side surface of the shutter element 120 is provided with a driver protrusion 122 for engaging a corresponding driver groove 222 of the rotor element. The opposite side surface of the shutter element 120 is provided with a linear guiding protrusion 121 for engaging a corresponding linear guide groove 101 of the housing 100 serving as a stator.

[0082] Fig. 10 shows a partial view of a tuyere stock of the present invention with a valve positioned at a preferred position.

[0083] Fig. 11 shows a housing of a valve body of an embodiment of the valve 1 of the present invention. The housing is a welded metal structure having flanges 104, 105 and a tubular portion 108 for receiving the worm shaft 110. The housing also comprises linear guiding grooves serving as abutments for corresponding guiding protrusions on the shutter elements.

[0084] Fig. 12 shows a rotor element contained in the housing of a valve body shown in Fig. 11, which serves as a bearing for rotating components and drive for the shutter elements. The rotor element has a worm gear 210 for engaging the worm shaft mounted in the tubular portion 108 of the housing. The rotor element is provided with driver grooves 222 engaging with corresponding drive protrusions on the shutter elements.

[0085] Fig. 13 shows a worm shaft 110 as part of the worm drive of a valve 1 according to the present invention: The worm shaft comprises a shaft body as the main cylindrical portion of the worm shaft. A helical thread is provided on the worm shaft, which is a continuous, spiral-shaped ridge that wraps around the shaft. The angle of the thread engages with the teeth of the worm gear. When the shaft rotates, the thread pushes against the gear teeth, causing the gear to rotate. At both ends of the worm shaft, bearings or bushings are installed to support the shaft. One end of the worm shaft is connected to a drive mechanism, such as an electric motor or handwheel, which provides the rotational force to turn the shaft.

[0086] Preferably, the worm shafts is made from steel, hardened steel.

[0087] Fig. 14 shows a perspective schematic view of a conventional blast furnace equipped with a blast system known from the prior art.

[0088] Fig. 15 shows a perspective view of a conventional tuyere stock known from the prior art.

[0089] Now, the method of opening and closing the valve as shown in the figures is described.

[0090] According to the present invention, for closing the valve from a fully open position, a worm shaft and worm gear mechanism is preferably used to precisely control a rotor element synchronizing the movement of six 6 shutter elements. The shutter elements move through a circumferential gap in the refractory-lined flow path to gradually close the valve, blocking the flow of hot gas. Accordingly, an operator or an automated system rotates the worm shaft. This worm shaft has helical threads that engage with the worm gear. As the worm shaft turns, it drives the worm gear, which, in turn, rotates the rotor element inside the valve housing. The rotor element is connected to the six shutter elements. As the rotor turns, it synchronously displaces all six shutter elements, causing them to move through the circumferential gap in the refractory-lined flow path. The shutter elements move inward, converging toward the center of the valve, gradually reducing the size of the aperture and closing the valve. As the worm shaft continues to turn, the shutter elements eventually obstruct the flow path to a maximum of 30 percent of the cross-sectional area without fully closing the flow path. When the shutter elements are closed, they form a tight seal in between them by engaging corresponding edges forming a hexagonal aperture in the plane of the cross-sectional area.

[0091] According to the present invention, for opening the valve from a fully closed position, the worm shaft is rotated in the reverse direction, which drives the worm gear and rotor element in reverse. The shutter elements are pulled outward, retracting from the circumferential gap and moving away from the flow path, allowing the aperture to expand. The valve moves to a fully open position, with the shutter elements no longer obstructing the flow, allowing for maximum flow through the valve.

[0092] To begin the valve opening process, the worm shaft is rotated in the opposite direction from the closing action. The reverse rotation drives the worm gear in the opposite direction as well, which in turn causes the rotor element to rotate in reverse. As the rotor element rotates in reverse, it causes the six triangular shutter elements to move outward, away from the center of the valve. This movement is synchronized, so all the shutter elements move simultaneously. The shutter elements are displaced from the circumferential gap in the refractory-lined flow path, retracting into their fully open positions toward the valve's inner wall. As the shutter elements are pulled back, the central aperture of the valve starts to expand. This opening enlarges the flow path, allowing more gas or material to pass through the valve. The hexagonal or circular aperture becomes wider as the shutters move outward, providing greater flow capacity. When the worm shaft has been rotated enough to fully retract the shutter elements, the valve reaches its fully open position. At this stage, the shutter elements are no longer obstructing the flow path, and the aperture is at its maximum size, allowing the hot gas to flow freely. The refractory sleeves in the flow path ensure that the valve continues to withstand high temperatures, and the circumferential gap allows the shutters to move without damaging the refractory lining. The valve remains fully open as long as the worm shaft and gear mechanism hold the shutter elements in their retracted position. No further adjustments are necessary unless the flow needs to be restricted or closed again.

Claims

1. A tuyere stock comprising a valve adapted to control the flow of a gas having a temperature of at least 800 °C into a furnace, the valve comprising (a) a valve body having a longitudinal axis and an inner wall defining a flow path for the gas along the axis, the flow path having a cross-sectional area perpendicular to the axis; (b) a trim assembly comprising multiple shutter elements and a drive assembly adapted to reversibly displace the multiple shutter elements from the inner wall of the valve body into the flow path in the plane of the cross-sectional area, the cross-sectional area of the flow path being concentrically reduced when the multiple shutter elements are displaced into the flow path.

2. The tuyere stock according to claim 1, wherein the trim assembly is adapted to reduce the cross-sectional area of the flow path to at most 30 percent of the cross-sectional area.

3. The tuyere stock according to claim 1 or 2, wherein the cross-sectional area of the flow path is concentrically increased when the multiple shutter elements are displaced out of the flow path.

4. The tuyere stock according to any one of the preceding claims, wherein the shape of the cross-section of the flow path defined by the shutter elements is a polygon, preferably a regular polygon, notably selected from a hexagon, octagon, decagon, dodecagon, tetradecagon, hexadecagon, octadecagon, and icosagon.

5. The tuyere stock according to any one of the preceding claims, wherein the shutter elements are adapted to slidingly engage adjacent shutter elements in a sealing manner.

6. The tuyere stock according to any one of the preceding claims, wherein the outer contours of the portion of the multiple shutter elements displaced through the inner wall into the flow path are the same.

7. The tuyere stock according to any one of the preceding claims, wherein the valve is mounted in the tuyere stock by means of detachable flange connections.

8. The tuyere stock according to any one of the preceding claims, wherein the shutter elements of the valve do not obstruct the flow path when the valve is fully open.

9. The tuyere stock according to any one of the preceding claims, wherein the highest velocity of the gas flow may be maintained at the center of the cross-sectional area when the shutter elements of the valve are displaced into the flow path.

10. The tuyere stock according to any one of the preceding claims, wherein the drive assembly is adapted to synchronously displace the shutter elements of the valve.

11. A use of a tuyere stock as defined in any one of claims 1 to 10 in a hot blast system of a furnace selected from a blast furnace, a Cupola furnace, a basic oxygen furnace, an electric arc furnace, a smelting furnace for non-ferrous metals, and a blast oxygen furnace for copper smelting.

12. A valve adapted to control the flow of a gas having a temperature of at least 800 °C into a furnace, the valve comprising (a) a valve body having a longitudinal axis and an inner wall defining a flow path for the gas along the axis, the flow path having a cross-sectional area perpendicular to the axis; (b) a trim assembly comprising multiple shutter elements displaceable from the inner wall of the wall body into the flow path in the plane of the cross-sectional area, the cross-sectional area of the flow path being concentrically reduced when the multiple shutter elements are displaced into the flow path.

13. A metallurgical installation or float glass installation equipped with a hot blast system having at least one tuyere stock according to any of claims 1 to 10 or a valve according to claim 11.

14. Method of controlling the flow of a gas having a temperature of at least 800 °C into a furnace, the method comprising the following steps: (i) providing a furnace equipped with a hot blast system having at least one tuyere stock according to any of claims 1 to 10 or a valve according to claim 11; (ii) concentrically reducing the cross-sectional area of the flow path of the gas by displacing the multiple shutter elements through the inner wall of the wall body into the flow path of the gas, or concentrically increasing the cross-sectional area of the flow path of the gas by displacing the multiple shutter elements out of the flow path of the gas.

15. Use of a valve as defined in claim 12 for controlling the flow of a high temperature gas into a furnace of a metallurgical installation or in the preparation and processing of sheet glass.

Images