Shaftless air heater

Abstract

The invention relates to an axial-free air heater, which comprises a burner system located at the top of a pre-chamber (1) having a chamber for mixing gas and air. The pre-chamber (1) has a jacket (2) with a lining, inside which there is an annular channel bounded by an inner annular wall (3) and an outer annular wall (4), thus forming a gas main (12). The lining of the pre-chamber (1) is supported on a metal ring beam (5), one wall of which is a continuation of the jacket (2), while the other forms a shell (7) of the vault-shaped part of the combustion chamber (6) and its bottom forms a support for the pre-chamber (1). The combustion chamber (6) together with the shell (7) and the lining (8) is arranged below the pre-chamber (1) and coaxially with it. The metal ring beam (5) is permanently connected with the jacket (2) and the shell (7) and is provided from above with a base plate (9), thus forming an air manifold (10). The outer annular wall (4) has openings with pipes (18) for supplying gas. Gas outlets (13) are arranged in a row at the top of the inner annular wall (3) and gas holes (14) are arranged at the bottom of the inner annular wall (3). The invention improves the operational safety and reliability by increasing the stability and durability of the axial-free air heater.

Description

Technical Field

[0001] This invention relates to an apparatus for heating blast air in a blast furnace. For blast air heating, air heaters of different designs are used: those with an internal combustion chamber, those with an external combustion chamber, and those without a conventional combustion chamber (top combustion or shaftless). Background Technology

[0002] It is known that air heaters without combustion chambers (shaftless air heaters) with a burner system installed at the dome of the air heater (Russian Patent 2145637, Inventor Certificate 602555, Japanese Patent 48-4284, US Patent 3473794) are more advanced devices.

[0003] Specifically, the shaftless air heater (patent number 2145637,2000) has a shell with a refractory lining, a lattice, a dome, a hot air outlet located above the lattice, the distance between the hot air outlet and the centerline of the lattice being not less than one diameter of its flow section, and a burner system including a pre-combustion chamber coaxially located at the top of the dome and having a shell with a refractory lining, the refractory lining being independent of the dome refractory lining and solely supported by the dome shell. In the pre-combustion chamber, there are annular gas and air collectors, one above the other, located between the shell and the sidewall of the pre-combustion chamber refractory lining, and separated from each other by partition plates. The collectors have inlet branches and outlet channels, the latter being formed in the vertical sidewall of the pre-combustion chamber refractory lining, and gas and air are supplied directly to the pre-combustion chamber. Because the centerline of the channels in the upper row of the lower collector points to the centerline of the pre-combustion chamber and is offset upwards by 30° from the horizontal plane, and the centerlines of all other channels are in the horizontal plane and point at an angle of 15-30° to the radius of the pre-combustion chamber at the center of their outlet portions, a vortex of gas and air is formed in the pre-combustion chamber. This vortex of airflow ensures complete combustion of the gas before it enters the lattice, and the airflow is evenly distributed across the lattice.

[0004] Air heaters for blast furnaces are large, high-temperature devices, and their construction and operation require significant costs. Therefore, reducing energy costs is one of the primary requirements. Furthermore, the air heaters burn a large amount of blast furnace fuel gas, including toxic gases such as carbon monoxide (CO). Therefore, ensuring the complete combustion of the fuel gas, which is environmentally safe, is crucial during the operation of the blast furnace air heaters.

[0005] A vortex of gas and air forms in the pre-combustion chamber to provide good mixing and combustion. Gas is supplied to the top of the pre-combustion chamber, where the gas vortex forms. To ensure good mixing of gas and air in known air heaters, the centerline of the air passages in the upper row of the lower collector is pointed towards the centerline of the pre-combustion chamber and offset upwards by an angle of up to 30° from the horizontal. The airflow, guided radially and moving upwards, is expected to reach the central portion of the pre-combustion chamber and provide good mixing and combustion at its center. Airflows from other rows are guided at an angle to the radius of the pre-combustion chamber and will provide good mixing and combustion of the peripheral gas flow. However, in air heaters installed in large blast furnaces, the pre-combustion chamber has a large cross-sectional size, and the airflow will have to overcome a strong, thick vortex of gas flow to reach the centerline of the pre-combustion chamber. This necessitates significantly increasing their velocity and installing powerful blowers, which increases energy costs. Furthermore, incomplete combustion of the gas may occur in the central portion of the pre-combustion chamber, leading to a deterioration in the environmental performance of the air heater. This creates a contradiction. On the one hand, to increase the penetration of the upper airflow, the airflow velocity must be significantly increased, and thus the pressure in the collector must be increased, which would require a significantly more powerful blower. On the other hand, the airflow from the channels of other rows does not require this increase in velocity because the gas is well mixed and completely combusted before entering the grid in the outer part of the pre-combustion chamber, and is in a normal velocity and flow vortex.

[0006] Therefore, different pressures are required for different rows of air coming from the same collector, which is impossible to provide. Because a blower using standard pressure provides air pressure in the collector, the airflow velocity from the upper row is insufficient, and the center of the pre-combustion chamber does not provide the amount of air needed for complete combustion. Consequently, some gas remains unburned and is released into the atmosphere, degrading the environmental and economic performance of the air heater.

[0007] According to the Kalugin shaftless air heater of patent RU2316600, the 2008 prototype most closely approximates the proposed invention through a combination of technical essence and features. The known air heater comprises: a shell with a refractory lining, a lattice body, an arch, a hot air outlet located above the lattice body, the hot air outlet being at least one diameter away from the centerline of the lattice body from its flow cross-section; a pre-combustion chamber coaxially located at the top of the arch, the pre-combustion chamber having a refractory lining shell, the refractory lining being independent of the arch refractory lining and solely supported by the arch shell; a gas and air collector, with a partition plate between the gas and air collector, the partition plate being located between the arch and the sidewalls of the pre-combustion chamber refractory lining, one above the other, and having an inlet branch and an outlet passage formed in the vertical sidewalls of the pre-combustion chamber refractory lining. In this configuration, the outlet channel of the lower collector is located at its upper part and is oriented upward at an angle of 15-30° from the horizontal plane, while the outlet channel of the upper collector is located at its lower part and is oriented downward at an angle of 15-30° from the horizontal plane. The projection of the centerline of the aforementioned channels onto the horizontal plane forms an angle of 15-45° with the projection of the radius of the pre-combustion chamber passing through the center of the channel outlet portion onto the horizontal plane.

[0008] Blast furnace air heaters involve equipment with a long service life (15-20 years) between repairs; therefore, operational reliability and long operating cycles are among the main requirements for these air heaters. In known air heaters, gas and air collectors, one above the other, are separated by a thin partition. The gas and air in the collectors can have different temperatures depending on the process conditions (heating of the gas or air). This difference is often quite significant, resulting in temperature deformation of the collector elements, which may damage the partition between them. In this situation, the gas and air mix, forming a flammable mixture that may burn or explode. Summary of the Invention

[0009] The purpose of this invention is to improve the safety and operational reliability of shaftless air heaters.

[0010] The improved stability and durability of shaftless air heaters result in enhanced operational safety and reliability.

[0011] Another technological advantage is the high efficiency of the air heater while its size is reduced.

[0012] The problem is addressed by claiming protection for a shaftless air heater comprising a burner having: an annular gas collector and a pre-combustion chamber, the cavity of which represents a chamber for mixing, ignition, and initial combustion of the gas and air stream; a combustion chamber for burning the gas mixture from the pre-combustion chamber, the combustion chamber having an arched shape at its upper part and located below the pre-combustion chamber; a lattice chamber for allowing the combustion products to pass through; the pre-combustion chamber, the combustion chamber, and the lattice chamber are interconnected and coaxially positioned, the pre-combustion chamber and the combustion chamber having their respective liners, wherein the diameter of the base of the pre-combustion chamber shell is larger than the diameter of the throat of the arched combustion chamber shell; the gas collector represents an annular channel implemented in the refractory lining of the pre-combustion chamber forming inner and outer annular walls; and a mixing chamber communicating with the annular air collector, into which the gas mixture enters... The outlet gas and air openings of the mixing chamber are formed in the inner annular wall. The gas and air openings are connected to corresponding gas and air branches from the outside via gas and air collectors. The air collector is located in the lower part of the pre-combustion chamber below the gas collector and represents the annular chamber formed by the cavity between the metal annular beam and the base plate. The base plate is mounted at the base of the pre-combustion chamber and is connected to each other and connected to the pre-combustion chamber and the combustion chamber shell. The metal annular beam forms a pre-combustion chamber support, and the base plate is provided with an opening for the air outlet of the air collector. The air outlet of the air collector is connected to the outlet air opening into the mixing chamber via an air supply channel. The outlet air opening is located in the inner annular wall below the outlet gas opening of the pre-combustion chamber, and the air supply channel is located in the lower part of the refractory lining of the pre-combustion chamber.

[0013] The metal ring beam is preferably made of low alloy steel and may have a right-angled triangular shape in its cross section, with one side serving as an extension of the pre-combustion chamber shell, the other side being formed by an arched combustion chamber shell, and the base being represented by a pre-combustion chamber support.

[0014] In a burner system, outlet gas openings for supplying gas to the mixing chamber are located at several heights in the inner annular wall of the mixing chamber toward the pre-combustion chamber, wherein the centerline of the opening has an inclination angle of 15° to 45° downward toward the horizontal plane.

[0015] The outlet air opening for supplying air to the mixing chamber is also located in the inner annular pre-combustion chamber wall, but at its lower part, where the centerline of the opening has an angle of inclination of 0° to 45° relative to the vertical plane.

[0016] The shape of the gas and air openings in the annular inner wall of the pre-combustion chamber refractory lining provides high efficiency for the air heater by creating a vortex that provides complete combustion of the gas and air mixture.

[0017] An air collector is connected to an air outlet to supply air into a mixing chamber through an air opening formed in the substrate and connected to an air supply channel implemented in the lower part of the pre-combustion chamber refractory lining.

[0018] The claimed design features an air collector, which forms the base of the pre-combustion chamber and is located outside the burner system. The air collector represents an annular chamber formed by a cavity between a metal annular beam and a base plate, which are connected to each other and to the pre-combustion chamber and combustion chamber housing. The operation of the air collector in the air heater provides directional airflow to interact with the airflow supplied to the gas and air mixing chamber. The design features of the air collector are implemented as an annular chamber located within the pre-combustion chamber support and aligned with the burner and the gas mixture combustion chamber. Combined with other features, this allows for the possibility of mixing gas and air in the central portion of the mixing chamber, eliminating the negative consequences associated with the burning of the partition between the gas collector and the air collector. In the claimed design, the gas collector and air collector are separated from each other by a thick layer of refractory lining, which eliminates the hazard of combustion and / or explosion of the gas and air mixture, thereby improving the operational reliability of the shaftless air heater and providing its high efficiency.

[0019] By comparing the design of the present invention, it can be concluded that it is characterized by new distinguishing features unknown from the prototype and the prior art, thereby providing new technical effects, namely, improved operational reliability due to the increased resistance of the air collector to temperature exposure during operation, and thus improved durability of the shaftless air heater. Attached Figure Description

[0020] The following figures illustrate a design that is claimed in one of the possible options for its implementation.

[0021] Figure 1 One possible implementation of a shaftless air heater is schematically shown in a longitudinal section.

[0022] Figure 2 and Figure 3 The same section is shown in cross-section. Detailed Implementation

[0023] The shaftless air heater of the present invention has a burner located at the top of a pre-combustion chamber 1, which has a mushroom shape and a cavity representing a gas and air mixing chamber. The pre-combustion chamber 1 has a shell 2, preferably made of low-alloy steel. The shell 2 of the pre-combustion chamber 1 is lined with a refractory material made of lightweight refractory material on its inner side. The refractory material lining of the pre-combustion chamber is made of heat-resistant refractory material from the side of the gas and air mixing chamber, forming an annular channel defined by an inner annular wall 3 and an outer annular wall 4. The refractory material lining of the pre-combustion chamber 1 is supported by a metal annular beam 5, which is made of low-alloy steel and has a right-angled triangular shape in its cross-section. One side of the beam serves as an extension of the shell 2 of the pre-combustion chamber 1, the other side is formed by the shell 7 of the domed combustion chamber 6, and the base is represented by a pre-combustion chamber support. Below the pre-combustion chamber 1 is a combustion chamber 6, which has an arched upper portion coaxial with and in communication with the pre-combustion chamber 1, and is provided with a shell 7, preferably made of low-alloy steel, and a lining 8 made of refractory material. In the interface region between the pre-combustion chamber 1 and the combustion chamber 6, the diameter of the shell 2 at the bottom of the pre-combustion chamber 1 exceeds the diameter of the shell 7 at the arched portion of the combustion chamber 6. A metal annular beam 5 is immovably connected to the shells 2 and 7, for example by welding, and a base plate 9 is provided from the top to form an inner chamber having a cavity that functions as an air collector 10. Below the combustion chamber 6 is a lattice chamber 11 with a refractory lattice structure (not shown), which is preferably made of hexagonal lattice bricks with layered perforations, such that the perforations of the layered lattice bricks allow for the passage of combustion products and heat transfer. Within the outer annular wall 4 of the pre-combustion chamber 1, there is an opening with a gas supply branch pipe 18. Between the inner annular wall 3 and the outer annular wall 4, there is a gas supply annular channel that functions as a gas collector 12. The upper part of the inner annular wall 3 has several outlet openings 13. These outlet openings allow the gas to move in the mixing chamber in the form of a vortex. For this purpose, the centerline of the openings has an inclination angle of 15-45° downward relative to the horizontal plane, thereby generating an effective gas vortex in the central part of the mixing chamber. The lower part of the inner annular wall 3 has an air opening 14 for supplying air to the mixing chamber of the pre-combustion chamber 1, and the centerline of the opening has an upward inclination angle of 0° to 45° relative to the vertical plane. The vortex of air flowing upward at a certain angle from the opening 14 meets the vortex of gas flowing downward at a certain angle from the outlet gas openings 13 in the mixing chamber of the pre-combustion chamber 1, and they mix in the mixing chamber of the pre-combustion chamber 1 to form a homogeneous fuel mixture, thereby providing complete combustion of the mixture. There is an opening in the side wall of the air collector 10, which has an air supply branch pipe 15 that enters the air collector 10.Air outlet 14, which enters the mixing chamber located at the lower part of the inner annular wall 3, communicates with air collector 10 through air passage 16 connected to air opening 17 in base plate 9. The communicating pre-combustion chamber 1 and the gas-air mixture combustion chamber 6 are arranged coaxially, and together with gas collector 12 and air collector 10, they form the burner system of the air heater to be protected. In the upper part of the air heater, there is a burner system represented by pre-combustion chamber 2, the cavity of which is the gas-air mixing chamber.

[0024] The claimed shaftless air heater operates as described below. In the cavity of the pre-combustion chamber 1, which represents the gas and air mixing chamber, mixing occurs between gas and air streams from the gas collector 12 and the air supply passage 16, which are connected to the air collector 10 via gas supply branch pipes 18 and 15, in which gas and air are supplied externally under pressure. A fuel mixture is formed due to the mixing of vortices entering the mixing chamber from outlets 13 and 14. This gas and air mixture is further burned in the domed portion of the combustion chamber 6. The resulting combustion chamber is supplied from the combustion chamber 6 to the lattice chamber 11.

[0025] The burner system of the air heater according to claim 1, formed by the interconnected pre-combustion chamber 1 and combustion chamber 6, is characterized in that the gas collector 12 and the air collector 10 are spatially separated relative to each other. This separation of the gas and air flow in the burner system, and the positioning of the air collector in the cavity formed by the pre-combustion chamber support, provides high efficiency of gas and air mixing and complete combustion of the resulting gas and air mixture, as well as safe and controlled operation of the gas and air supply area, wherein the pre-combustion chamber support is the most stress-bearing area of ​​the air heater. This effectively eliminates uncontrolled mixing of gas and air in the pre-combustion chamber of the burner system, eliminates the risk of mixture ignition or explosion, and provides complete combustion of gas during fully safe operation of the air heater. Furthermore, the use of a metal annular beam for the pre-combustion chamber support and the placement of the annular collector therein allows for a reduction in size due to the reduced height of the air heater, reducing capital expenditure and thus lowering costs during the installation of new air heaters and the retrofitting of existing air heaters.

Claims

1. A shaftless air heater comprising a burner system having an annular gas collector and a prechamber, the cavity of the prechamber representing a chamber for mixing, ignition and initial combustion of a gas and air stream; A combustion chamber for burning an air-gas mixture from a pre-chamber, said combustion chamber having a dome-like shape in its upper part and being located below said pre-chamber; a lattice chamber for passing the generated combustion products; said pre-chamber, said combustion chamber and said lattice chamber are in communication with each other and are located coaxially, said pre-chamber and said combustion chamber are provided with respective liners, wherein the diameter of the pre-chamber liner base is greater than the diameter of the dome-like combustion chamber liner throat, a gas collector represents an annular passage implemented in the pre-chamber refractory lining forming an inner annular wall and an outer annular wall; A mixing chamber is in communication with an annular air collector, outlet gas and air openings into said mixing chamber are formed in said inner annular wall, said outlet openings are in communication with respective gas and air branch pipes from the outside through the gas and air collectors, characterized in that said air collector is located in the lower part of the pre-chamber below said gas collector and represents an annular chamber formed by a cavity between a metal annular beam and a base plate, said base plate is mounted at the base of said pre-chamber and is connected to each other and to the pre-chamber and combustion chamber liners, wherein said metal annular beam forms a pre-chamber support and said base plate is provided with openings for air outlets of the air collector, which are in communication with outlet air openings into the mixing chamber through air supply passages, said outlet air openings are located in the inner annular wall below the outlet gas openings of the pre-chamber, and said air supply passages are located in the lower part of the pre-chamber refractory lining.

2. The shaftless air heater of claim 1, wherein, The outlet gas openings into the mixing chamber from the gas collector in the burner system are located in the inner annular wall at multiple levels.

3. The shaftless air heater of claim 1, wherein, The centerline of the outlet gas openings into the mixing chamber from the gas collector is made with an angle of inclination of 15° to 45° downward relative to the horizontal plane.

4. The shaftless air heater of claim 1, wherein, The centerline of the outlet air openings into the mixing chamber from the air collector is made with an inclination angle of 0° to 45° relative to the vertical plane.

5. The shaftless air heater of claim 1, wherein, The metal annular beam is made of low-alloy steel.

6. The shaftless air heater of claim 1, wherein, The metal annular beam has the shape of a right-angled triangle in its cross-section, one side of the right-angled triangle serves as an extension of the pre-chamber liner, the other side is formed by the liner of the dome-like combustion chamber, and the base is represented by the pre-chamber support. The metal annular beam is made of low-alloy steel. The metal annular beam has the shape of a right-angled triangle in its cross-section, one side of the right-angled triangle serves as an extension of the pre-chamber liner, the other side is formed by the liner of the dome-like combustion chamber, and the base is represented by the pre-chamber support.

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