JP7351010B2 - shaftless air heater - Google Patents

Description

The present invention relates to a blast heating device used in a blast furnace.

Air heaters of different designs are used for heating blast furnaces: with an internal combustion chamber, with an external combustion chamber, and without a conventional combustion chamber (top combustion, shaftless). As a more advanced air heater, an air heater without a combustion chamber (shaftless air heater) in which a burner system is installed in the dome of the air heater is known (Russian Patent No. 2145637, Inventor Certificate No. 602555) , Japanese Patent No. 48-4284, US Patent No. 3473794).

In particular, the shaftless air heater (Patent No. 2,145,637, 2000) has a shell with a refractory lining, a lattice refractory brick, a dome, a distance of more than a diameter above the lattice refractory brick to the centerline of the cross-section of the hot air flow. a burner system comprising a hot air outlet located at a distance, as well as a prechamber with a refractory lining shell located coaxially therewith at the top of the dome and carried out independently of the dome refractory lining with individual support by the dome shell; ing. Within the prechamber, between the shell and the sidewalls of the prechamber refractory lining, there is an annular gas and air collector located one above the other, separated by a partition plate. The dust collector has an inlet branch pipe and a discharge nozzle, the discharge nozzle is made on the vertical side wall of the prechamber refractory lining, and the gas and air are directly supplied to the prechamber. The centerline of the nozzle of the upper stage of the lower collector is directed towards the centerline of the prechamber and is offset upward at an angle of 30° from the horizontal plane, and the centerline of all other nozzles is in the horizontal plane, its discharge part A swirling flow of gas and air is formed in the prechamber due to the fact that it is oriented at an angle of 15-30° to the prechamber radius passing through the center of the prechamber. This swirling flow has the effect of completely combusting the gas before it enters the grate refractory, and evening out the flow throughout the grate refractory.

Air heaters for blast furnaces are large, high-temperature vessels, and their construction and operation are costly. Therefore, reducing energy costs is one of the major requirements. Furthermore, inside a blast furnace, a large amount of blast furnace gas containing carbon monoxide (CO), a harmful gas, is burned. Therefore, when operating a blast furnace hot blast furnace, environmental safety through complete combustion of gas is an important requirement.

A swirling flow of gas and air is created for good mixing and combustion within the prechamber. Gas is supplied to the top of the prechamber where a swirling flow of gas is formed. To enable good gas-air mixing in known air heaters, the center line of the air nozzles of the upper row of the lower collector is oriented towards the center line of the prechamber and at an angle of up to 30° from the horizontal plane. It was shifted upwards. The radially directed and upwardly shifted air flow is expected to pass through the gas flow toward the center of the prechamber and improve the mixing and combustion of the gases in the center of the prechamber. The air flow from the other rows of nozzles shall be directed obliquely to the prechamber radius to better mix and burn the gas flow in the periphery. However, in an air heater installed in a large blast furnace, the prechamber has a large cross-sectional dimension, and the airflow must overcome a strong swirling gas flow with high concentration to reach the centerline of the prechamber. Therefore, it is necessary to significantly increase the speed and install a powerful blower, which increases energy costs. In addition, incomplete combustion of gas occurs in the center of the prechamber, leading to deterioration of the environmental performance of the air heating device. In this case, a contradiction arises. On the other hand, in order to increase the penetration power of the airflow, it is necessary to significantly increase its speed, which in turn increases the pressure inside the dust collector, so it is necessary to significantly increase the capacity of the blower. On the other hand, for the air flow from the other rows of nozzles, the normal velocity and flow swirl will ensure good mixing and complete combustion of the gases before entering the grate refractory at the periphery of the prechamber. This speed increase is not necessary.

Different rows of nozzles within the same collector therefore require different pressures, which cannot be provided. In addition, since a blower with standard pressure is used for the air pressure inside the dust collector, the flow rate of air from the upper nozzle is insufficient, and the amount of air necessary for complete combustion of gas is not supplied to the center of the prechamber. As a result, some of the gas is not combusted and is emitted into the atmosphere, deteriorating the environmental and economic efficiency of the air heating device.

The prototype of the Kalugin Shaftless Air Heater of patent RU No. 2316600 of 2008 is the closest to the proposed invention by the totality of its technical essence and features. The known air heater consists of a shell with a refractory lining, a lattice refractory dome, a hot air outlet located above the lattice refractory at a distance not less than one diameter of its flow section to its center line, and a dome coaxial with it. It consists of a shell with a refractory lining located on top of the dome shell and independent of the dome refractory lining with individual support by the dome shell. A gas and air collector located between the dome and the side wall of the pre-chamber refractory lining and having a partition plate therebetween, the inlet branch pipe and the discharge provided in the vertical side wall of the pre-chamber refractory lining. Gas and air collector with nozzle. In this case, the discharge nozzle of the lower collector is located in its upper part and directed upwards at an angle of 15° to 30° from the horizontal plane, and the outlet nozzle of the upper collector is located in its lower part and oriented upward at an angle of 15° from the horizontal plane. Directed downward at an angle of ~30°, the projection of the centerline of these nozzles into the horizontal plane forms an angle of 15° to 45° with the projection of the prechamber radius through the center of the nozzle emission into the horizontal plane. ing.

Air heating devices for blast furnaces concern equipment with long repair intervals (15-20 years), and therefore operational reliability and long-term operation are among the major requirements for these air heating devices. In a known air heater, gas and air dust collectors arranged above and below are separated by a thin partition plate. The gas and air in the precipitator may have different temperatures depending on the process conditions (heating of the gas or air). This temperature difference is often quite large, resulting in temperature deformation of the dust collectors, which can result in damage to the partition plates between the dust collectors. In this case, a mixture of gas and air occurs, forming a flammable mixture that can ignite or explode.

The purpose of the invention is to increase the safety and operational reliability of shaftless air heaters.

The technical result is improved operational safety and reliability due to improved stability and durability of the shaftless air heater.

Furthermore, as a technical result, it is possible to reduce the dimensions of the air heater and at the same time obtain high efficiency.

This problem is solved by using a shaftless air heater. The shaftless air heater includes a burner with an annular gas collector, a prechamber having a cavity representing a chamber for mixing, ignition, and initial combustion of gas and air streams, and a dome shape at the top of the prechamber. a chamber for combustion of the gas mixture from the prechamber, and a grate refractory chamber for passing the generated combustion products. In the shaftless air heater, the prechamber, the combustion chamber, and the grate refractory chamber are interconnected and coaxially located, and the prechamber and the combustion chamber each have their own liner shell. , the diameter of the shell base of the prechamber is larger than the diameter of the throat of the shell of the dome-shaped combustion chamber, and the gas collector forms an inner annular wall and an outer annular wall of the prechamber refractory. an annular channel implemented in the refractory lining of the mixing chamber, wherein the mixing chamber is in interconnection with an annular air collector, nozzles for discharge gas and air to the mixing chamber are made in the inner annular wall; The nozzle interconnects with the respective gas and air branch pipes from the outside through the gas and air collector, the difference being that the air collector is located at the lower part of the prechamber below the gas collector. , represents an annular chamber formed by a cavity between the metal annular beam and a base plate, the base plate being installed at the bottom of the pre-chamber and connected to each other and connected to the shells of the pre-chamber and the combustion chamber. These are connected points. the metal annular beam forms a pre-chamber support, the base plate is provided with holes for air discharge from the air collector intercommunicating with a discharge air nozzle to the mixing chamber via the air supply channel; The latter is located in the inner annular wall below the discharge gas nozzle to the mixing chamber, and the air supply channel is located below the refractory lining of the prechamber.

The metal annular beam is preferably made of low-alloy steel, and the cross section of the metal annular beam may have the shape of a right triangle, one side of the right triangle serving as an extension of the prechamber shell; The other side of the right triangle is formed by the domed combustion chamber shell, and the bottom is represented by the prechamber support.

In the burner system, the discharge gas nozzles for feeding into the mixing chamber are arranged at a plurality of heights of the inner annular wall facing the pre-chamber mixing chamber, and the center line of these nozzles lies in a horizontal plane. It has a downward inclination angle of 15° to 45°.

The discharge air nozzles for supplying the mixing chamber are also arranged on the inner annular prechamber wall, but at the bottom, the center lines of these nozzles are at an angle of 0° to 45° with respect to the vertical plane. It has an inclination angle of .

By arranging the gas and air nozzles on the inner annular wall of the prechamber in this way, a swirling flow can be created to completely burn the gas and air mixture, thereby increasing the efficiency of the air heater.

The air collector communicates with a discharge air nozzle for supplying the mixing chamber through air holes provided in the base plate and with a channel for air supply provided in the lower part of the prechamber refractory lining.

The present structure features an air collector located at the bottom of the prechamber and outside the burner system. In this case, the air collector represents an annular chamber formed by a cavity between a base plate and a metal annular beam connected to each other and to the prechamber wall and the combustion chamber wall. Operation of the air collector of the air heating device provides an upward movement of the air stream to interact with the gas stream supplied to the gas and air mixing chamber. The design features of the air collector, implemented as an annular chamber located on the prechamber support, together with the mutual arrangement of the burner and the gas-mixing combustion chamber and other attributes, ensure that the gas and air flow in the central part of the mixing chamber is It is possible to offer mixing possibilities. In the claimed design, the gas and air collectors are separated from each other by a huge layer of refractory lining, thus eliminating the negative effects regarding burnout of the partition plates between the gas and air collectors and preventing the gas and air mixture ignition and/or explosion hazards, thereby increasing operational reliability and providing high efficiency of shaftless air heaters.

A comparison of the claimed design shows that it is characterized by new characteristic features unknown from the prototype and the known state of the art and that it achieves a new technical result, i.e. the air collector against temperature exposure during operation. It is possible to conclude that it provides improved operational reliability due to improved stability and thus durability of the shaftless air heater.

The claimed design is shown in the following figure in one of its possible implementation options.
1 shows one possible embodiment of the shaftless air heater in longitudinal section; FIG. Figure 2 shows a cross section of the shaftless air heater of Figure 1; Figure 2 shows a cross section of the shaftless air heater of Figure 1;

The claimed shaftless air heater places the burner at the top in a prechamber 1 whose cavity has a mushroom shape representing a gas and air mixing chamber. The prechamber 1 has a shell 2 preferably made of low alloy steel. The shell 2 of the prechamber 1 has a refractory lining made of a lightweight refractory formed inside the shell 2. On the side of the gas-air mixing chamber, a pre-chamber refractory lining made of heat-resistant refractory is used, forming an annular flow path delimited by an inner annular wall 3 and an outer annular wall 4. The refractory lining of the prechamber 1 is made of low-alloy steel and is supported by a metal annular beam 5 whose cross section has the shape of a right triangle, one side of which serves as an extension of the shell 2 of the prechamber 1. , the other side is formed by the shell 7 of the dome-shaped combustion chamber 6, and the bottom is represented by the prechamber support. Below the prechamber 1, it has a domed upper part located coaxially with the prechamber 1 and in communication with the prechamber 1, with a shell 7 preferably made of low alloy steel and a lining 8 made of refractory material. There is a combustion chamber 6 comprising. In the interface area between the prechamber 1 and the combustion chamber 6, the bottom shell 2 of the prechamber 1 has a diameter that exceeds the diameter of the shell 7 of the domed part of the combustion chamber 6. The metal annular beam 5 is permanently connected, for example by welding, with the shells 2 and 7, which is provided from above with a base plate 9 forming an internal chamber with a cavity that serves as an air collector 10. Below the combustion chamber 6 there is a lattice refractory chamber 11 with refractory lattice refractory bricks (not shown), preferably made of hexagonal refractory bricks, in which holes in the refractory bricks laid in layers are used for combustion. It has holes laid in layers to provide product passage and heat transfer. In the outer annular wall 4 of the prechamber 1 there is a hole 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 wall which serves the function of a gas collector 12. There is a channel. In the upper part of the inner annular wall 3 there are discharge nozzles 13 arranged in several rows, which provide for the movement of the gas in the form of a swirling flow in the mixing chamber, for which purpose the center line of these nozzles is It has an angle of inclination of 15 to 45° downward with respect to the horizontal plane, thereby creating an efficient swirling flow of gas in the central part of the mixing chamber. In the lower part of the inner annular wall 3 there are air nozzles 14 supplying air to the mixing chamber of the prechamber 1, the center lines of these nozzles having an upward slope angle of 0 to 45° with respect to the vertical plane . The swirling flow of air diagonally upward from the nozzle 14 meets the swirling flow of gas diagonally downward from the discharge gas nozzle 13 in the mixing chamber of pre-chamber 1, and mixes with them in the mixing chamber of pre-chamber 1 to become homogeneous. forming a fuel mixture, thereby causing complete combustion of this mixture. In the side wall of the air collector 10 there is a hole with an air supply branch 15 to the air collector 10. Discharge air nozzles 14 to the mixing chamber located in the lower part of the inner annular wall 3 communicate with the air collector 10 via air channels 16 connected to air holes 17 in the base plate 9. The intercommunicating pre-chamber 1 and the gas-air mixing combustion chamber 6 are coaxially located together with the gas collector 12 and the air collector 10, and on top thereof are represented by the pre-chamber 2, which is the gas-air mixing chamber. forming a burner system of an air heater according to the claims.

The shaftless air heater according to the claims operates as shown below. In the cavity of the prechamber 1, which represents a gas and air mixing chamber, gas and Mixing of the air streams takes place, supplying gas and air under external pressure. A fuel mixture is formed by the mixing of the swirling flows from the discharge gas nozzle 13 and the discharge air nozzle 14 towards the mixing chamber, and the formed gas and air mixture is further ignited and combusted in the dome-shaped part of the combustion chamber 6. The resulting combustion chamber is fed from the combustion chamber 6 to the grate refractory chamber 11.

The burner system of the air heater according to the claims, which is formed by an intercommunicating prechamber 1 and a combustion chamber 6, provides that the gas collector 12 and the air collector 10 are spatially separated relative to each other. Features. By thus separating the gas and air flows in the burner system and placing the air collector in the cavity formed by the prechamber support, which is the most stressed area of the air heater, the High mixing efficiency, ensuring complete combustion of the resulting gas-air mixture, as well as safe control of the gas and air supply area. This eliminates chaotic mixing of gas and air in the prechamber of the burner system, eliminates the risk of ignition or explosion of the mixture, and ensures complete combustion of the gas with completely safe operation of the air heating device. do. Furthermore, by using a metal annular beam for prechamber support and locating an annular collector within it, the height of the air heater is reduced, thereby reducing its dimensions and reducing capital investment, thereby reducing new Costs can be reduced both when installing air heaters and when rebuilding existing ones.

Claims (6)

a burner system comprising a prechamber having an annular gas collector and a cavity containing a mixing chamber for mixing of gas and air streams, ignition, and initial combustion, and having a dome shape at the top and provided below said prechamber; A shaftless air heater comprising a chamber for combustion of a gas mixture from the prechamber and a grate refractory chamber for passing generated combustion products, the shaftless air heater comprising:
The prechamber, the combustion chamber, and the grate refractory chamber are interconnected and coaxially located, the prechamber and the combustion chamber each having a shell of a liner ; the diameter of the bottom of the shell is greater than the diameter of the neck of the shell of said dome-shaped combustion chamber;
the annular gas collector exhibits an annular channel implemented in the refractory lining of the prechamber forming inner and outer annular walls of the prechamber refractory, the mixing chamber intercommunicating with an annular air collector; A discharge gas nozzle and a discharge air nozzle to the mixing chamber are made in the inner annular wall, and the discharge gas nozzle and discharge air nozzle supply respective gases from the outside via the gas collector and air collector. Intercommunicating with branch pipes and air branch pipes;
The air collector includes an annular chamber located in the lower part of the pre -chamber below the annular gas collector and formed by a cavity between a metal annular beam and a base plate, the base plate being in contact with the pre-chamber. located at the bottom of the chamber and connected to each other and to the shells of the prechamber and the combustion chamber ;
the metal annular beam forms a pre-chamber support, the base plate is provided with holes for air discharge from the air collector interconnecting with a discharge air nozzle to the mixing chamber via an air supply channel; the discharge air nozzle is located in the inner annular wall below the discharge gas nozzle to the mixing chamber, and the air supply channel is located under the refractory lining of the prechamber;
This is a shaftless air heater. 2. The shaftless air heater of claim 1, wherein the discharge gas nozzle extending from the annular gas collector into the mixing chamber in the burner system is arranged at multiple levels of the inner annular wall. Shaftless air heater. The shaftless air heater according to claim 1, wherein the centerline of the discharge gas nozzle has a downwardly inclined angle of 15° to 45° with respect to a horizontal plane. The shaftless air heater of claim 1, wherein the centerline of the discharge air nozzle from the annular gas collector to the mixing chamber has an angle of inclination of 0° to 45° with respect to the vertical plane. Shaftless air heater. The shaftless air heater according to claim 1, wherein the metal annular beam is made of low alloy steel. 2. The shaftless air heater according to claim 1, wherein the metal annular beam has a cross section in the shape of a right triangle, one side of the right triangle functions as an extension of the prechamber shell, and the right triangle The other side of the shaftless air heater is defined by the shell of the dome- shaped combustion chamber, and the bottom part is represented by the pre-chamber support.

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