JP2023502104A - shaftless air heater - Google Patents

Abstract

A shaftless air heater comprising a burner system placed on top of a pre-chamber (1) comprising a chamber for mixing gas and air. Said prechamber (1) has a jacket (2) with a liner. An annular duct is provided inside said jacket (2). Said duct is surrounded by an inner annular wall (3) and an outer annular wall (4) to form a gas collecting part (12). The liner of said prechamber (1) is supported by a metal ring beam (5), one wall of said jacket (2) representing an extension of said jacket (2), while the other wall of said jacket (2). denotes the profile of the dome-shaped part of the combustion chamber (6), the bottom of which constitutes the support of said pre-chamber (1). Said combustion chamber (6) with profile (7) and liner (8) is arranged below said pre-chamber (1) and coaxially with said pre-chamber (1). Said metal ring beam (5) is permanently connected with said jacket (2) and said profile (7) and provided with a base plate from above to form an air manifold (10). Said outer annular wall (4) has an opening with a pipe (18) for supplying gas. Gas outlets (13) are arranged in rows at the top of said inner annular wall (3) and air holes (14) are provided at the bottom of said inner annular wall (3). The present invention improves operational safety and reliability by improving the stability and durability of shaftless air heaters.

Description

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

Different designs of air heaters are used for heating blast furnaces: with internal combustion chamber, with external combustion chamber and without conventional combustion chamber (top firing, shaftless). A more advanced air heater is known as an air heater without a combustion chamber (shaftless air heater) with a burner system installed in the dome of the air heater (Russian Patent No. 2145637, Inventor's Certificate No. 602555 , Japanese Patent No. 48-4284, U.S. Patent No. 3473794).

In particular, a shaftless air heater (Patent No. 2145637, 2000) is used for shells with refractory linings, grate refractory bricks, domes, above grate refractory bricks and spaced apart by more than a diameter to the cross-sectional centerline of the flow of hot air. and a pre-chamber having a hot air outlet located at a distance and a refractory lining shell located coaxial therewith in the upper part of the dome and independently of the dome refractory lining with individual support by the dome shell. ing. Within the prechamber are annular gas and air collectors between the shell and the side walls of the prechamber refractory lining, separated from each other by dividers and positioned above one another. The dust collector has an inlet branch and a discharge nozzle, the discharge nozzle is made in the vertical sidewall of the prechamber refractory lining, and the gas and air are supplied directly to the prechamber. The centerline of the upper tier of nozzles of the lower collector is directed towards the centerline of the prechamber and is offset upwards at an angle of 30° from the horizontal plane, the centerlines of all other nozzles are in the horizontal plane, and the discharge portion of the A swirling flow of gas and air is created in the prechamber due to the fact that it is oriented at an angle of 15-30° to the prechamber radius through the center of the chamber. This swirling flow has the effect of causing the gas to burn completely before entering the lattice refractory bricks and to make the flow uniform throughout the lattice refractory bricks.

Blast furnace air heaters are large, high-temperature vessels that are expensive to construct and operate. Therefore, reduction of energy cost is one of the major requirements. Also, in the blast furnace, a large amount of blast furnace gas containing carbon monoxide (CO), which is a harmful gas, is burned. Therefore, environmental safety due to complete combustion of gas is an important requirement in the operation of blast furnace hot stoves.

A swirling flow of gas and air is created for good mixing and combustion in the prechamber. Gas is supplied to the top of the prechamber, where a swirling flow of gas is formed. In order to allow good gas-air mixing in known air heaters, the centerline of the air nozzles in the upper row of the lower collector is directed to the centerline of the prechamber and at an angle of up to 30° from the horizontal plane. was shifted upwards. A radially directed, upwardly offset air flow is directed through the gas flow toward the center of the prechamber and is expected to provide better mixing and combustion of the gases in the center of the prechamber. Airflow from other rows of nozzles should be directed obliquely to the prechamber radius to provide good mixing and combustion of the peripheral gas flow. However, in an air heater installed in a large blast furnace, the cross-sectional dimension of the pre-chamber is large, and the air flow must reach the center line of the pre-chamber over a strong swirling gas flow of high concentration. For this reason, it is necessary to greatly increase the speed and install a powerful blower, which increases the energy cost. In addition, incomplete combustion of gas occurs in the center of the pre-chamber, leading to deterioration of the environmental performance of the air heater. In this case a contradiction arises. On the other hand, in order to increase the penetrating power of the air flow, it is necessary to greatly increase its speed, and as a result, the pressure inside the dust collector also increases, so it is necessary to greatly increase the capacity of the blower. On the other hand, for the airflow from the other rows of nozzles, the normal velocity and swirl of the flow before entering the grate refractories at the perimeter of the prechamber allow for good mixing and complete combustion of the gases. This speed increase is not required.

Therefore, different rows of nozzles in the same collector require different pressures, which cannot be provided. In addition, since the air pressure in the dust collector uses a standard pressure blower, the flow rate of the air from the upper nozzle is not sufficient, and the amount of air required for complete combustion of the gas is not supplied to the central part of the pre-chamber. As a result, part of the gas is discharged into the atmosphere without being burned, which deteriorates the environmental and economic efficiency of the air heater.

Patent RU 2316600, 2008 Kalugin Shaftless Air Heater Prototype is closest to the proposed invention in terms of overall technical essence and features. Known air heaters consist of a shell with a refractory lining, a grate refractory brick, a dome, a hot air outlet located above the grate refractory at a distance not less than one diameter of its flow section to its centerline, and a dome coaxial therewith. and consists of a shell with a refractory lining that is 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 walls of the prechamber refractory lining and having a partition therebetween, the inlet manifold and discharge on the vertical side walls of the prechamber refractory lining. Gas and air collector with nozzle. In this case, the discharge nozzle of the lower collector is located above it and is directed upwards at an angle of 15° to 30° from the horizontal, and the outlet nozzle of the upper collector is located below it and is 15° from the horizontal. 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 discharge into the horizontal plane. ing.

Blast furnace air heaters are concerned with equipment with long service intervals (15-20 years), therefore operational reliability and long term operation are one of the major requirements for these air heaters. In known air heaters, gas and air dust collectors arranged one above the other are separated by a thin partition. The gas and air in the precipitator can have different temperatures depending on the process conditions (gas or air heating). This temperature difference is often quite large and can result in thermal deformation of the dust collectors, with consequent damage to the partitions between the dust collectors. In this case, mixing of gas and air occurs, forming a flammable mixture which can ignite or explode.

SUMMARY OF THE INVENTION It is an object of the present invention to increase the safety and operational reliability of shaftless air heaters.

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

Moreover, as a technical result, it is possible to reduce the dimensions of the air heater while at the same time obtaining high efficiency.

This problem is solved by using shaftless air heaters. The shaftless air heater comprises a burner with an annular gas collector, a prechamber with a cavity representing a chamber for mixing, ignition and initial combustion of the gas and air streams, and a dome shape on top of the prechamber. and a chamber for combustion of the gas mixture from the prechamber and a grate refractory brick chamber for passing the products of combustion generated. In the shaftless air heater, the prechamber, the combustion chamber, and the grate refractory chamber are interconnected and coaxially positioned, the prechamber and the combustion chamber each having their own shell of liner. said prechamber shell base having a diameter greater than said dome-shaped combustion chamber shell throat diameter, said gas collector forming an inner annular wall and an outer annular wall of said prechamber refractory; wherein said mixing chamber is interconnected with an annular air collector, nozzles for discharge gas and air to said mixing chamber are made in said inner annular wall, said gas and discharge The nozzles are interconnected with respective gas and air branch pipes from outside via said gas and air collectors, the difference being that said air collectors are located in the lower part of said pre-chamber below said gas collectors. , representing an annular chamber formed by a cavity between said metal annular beam and a base plate, said base plate being located at the bottom of said pre-chamber and connected to each other and to the shells of said pre-chamber and said combustion chamber. The points are connected. said metal annular beam forming a pre-chamber support, said base plate having holes for air discharge from said air collector interconnecting with a discharge air nozzle to said mixing chamber through said 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 under 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, and the The other side of a right triangle is formed by said domed combustion chamber shell and the bottom is represented by said pre-chamber support.

In said burner system said discharge gas nozzles for feeding into said mixing chamber are arranged at multiple levels of the inner annular wall towards the pre-chamber mixing chamber, the center line of these nozzles being in the horizontal plane. It has a downward inclination angle of 15° to 45°.

The discharge air nozzles for feeding the mixing chamber are also arranged in the inner annular pre-chamber wall, but below it the centerline of these nozzles is 0° to 45° to the vertical plane. has an inclination angle of

By arranging the gas and air nozzles in the inner annular wall of the prechamber in this way, a swirling flow can be created for complete combustion of the gas and air mixture, increasing the efficiency of the air heater.

The air collector communicates with a discharge air nozzle for supplying the mixing chamber through air holes in the base plate and with channels for air supply in the lower part of the pre-chamber 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 the annular chamber formed by the cavity between the base plate and the metal annular beams connected to each other and to the pre-chamber wall and the combustion chamber wall. The operation of the air collector of the air heater provides an upward movement of the air flow to interact with the gas flow supplied to the gas and air mixing chamber. A design feature of the air collector implemented as an annular chamber located in the prechamber support, along with the interposition of the burner and the gas mixing combustion chamber and other attributes, is the distribution of gas and air in the middle of the mixing chamber. It is to make it 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 adverse effects of burn-out of the partition between the gas and air collectors, thus eliminating 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 features new characteristic features not known from prototypes and known state of the art and achieves new technical achievements, i.e. air collectors for temperature exposure during operation It is possible to conclude that the improved stability of the heater provides improved operational reliability and thus durability of the shaftless air heater.

The claimed design is shown in the following figure in one of its possible 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 lightweight refractory on the inner side of the shell 2 . On the side of the gas and air mixing chamber, a pre-chamber refractory lining of refractory refractory forming an annular flow path bounded by an inner annular wall 3 and an outer annular wall 4 is used. 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 domed combustion chamber 6 and the bottom is represented by the pre-chamber support. Beneath the prechamber 1 is a dome-shaped upper portion coaxial with the prechamber 1 and interconnected with the prechamber 1, preferably containing a shell 7 of low alloy steel and a lining 8 of refractory material. There is a combustion chamber 6 with. In the interface region between the prechamber 1 and the combustion chamber 6 , the bottom shell 2 of the prechamber 1 has a diameter exceeding the diameter of the shell 7 of the domed portion of the combustion chamber 6 . A metal annular beam 5 is permanently connected, for example by welding, to the shells 2 and 7, which is provided from above with a base plate 9 forming an internal chamber with a cavity serving as an air collector 10. Below the combustion chamber 6 is a grate refractory chamber 11 with refractory grate refractory bricks (not shown), preferably of hexagonal refractory bricks, with holes in the layered refractory bricks for combustion. It has holes laid in layers to provide product passage and heat transfer. The outer annular wall 4 of the prechamber 1 has a hole with a gas supply branch 18 and between the inner annular wall 3 and the outer annular wall 4 a gas supply annular which serves as a gas collector 12. have 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 within the mixing chamber, for which purpose the centerline of these nozzles is It has an angle of inclination of 15 to 45° downward to the horizontal, thereby creating an efficient swirling flow of gas in the middle of the mixing chamber. In the lower part of the inner annular wall 3 there are air nozzles 14 feeding the mixing chamber of the prechamber 1, the center line of these nozzles having an angle of inclination from 0 to 45° upwards with respect to the vertical plane. . The swirl flow of air directed obliquely upward from the nozzle 14 meets the swirl flow of gas directed obliquely downward from the discharge gas nozzle 13 in the mixing chamber of the pre-chamber 1 and mixes with them in the mixing chamber of the pre-chamber 1 to produce a homogeneous mixture. form a stable fuel mixture thereby allowing complete combustion of this mixture. The side wall of the air collector 10 has holes with air supply branches 15 to the air collector 10 . A discharge air nozzle 14 to the mixing chamber located in the lower part of the inner annular wall 3 communicates with the air collector 10 via air channels 16 connected to air holes 17 in the base plate 9 . Intercommunicating pre-chamber 1 and mixed gas-air combustion chamber 6 are located coaxially with gas collector 12 and air collector 10 and are represented above it by pre-chamber 2 which is a gas-air mixing chamber. Forming the burner system of the air heater according to claim 1, there is a burner which is

The claimed shaftless air heater operates as follows. In the cavity of the pre-chamber 1, which represents the gas and air mixing chamber, gas and air go from an air supply line 16 interconnecting gas collector 12 and air collector 10 via gas supply branch 18 and air supply branch 15, respectively. Airflow mixing occurs and gas and air are supplied under external pressure. A fuel mixture is formed by swirling mixing from the discharge gas nozzle 13 and the discharge air nozzle 14 into the mixing chamber, and the formed gas-air mixture is further ignited and combusted in the domed portion of the combustion chamber 6 . The resulting combustion chamber is fed from combustion chamber 6 to grate refractory brick chamber 11 .

The burner system of the claimed air heater formed by the interconnecting pre-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. Characterized by By thus separating the gas and air flows in the burner system and placing the air collector in the cavity formed by the pre-chamber support, which is the most stressed area of the air heater, High mixing efficiency allows complete combustion of the resulting gas and air mixture, as well as safe control of the gas and air supply area. This eliminates chaotic mixing of gas and air in the pre-chamber of the burner system, eliminates the risk of mixture ignition or explosion, and ensures complete combustion of the gas with completely safe operation of the air heater. do. Furthermore, by using a metal annular beam for the prechamber support and placing the annular collector in it, the height of the air heater is reduced, thus reducing its size and capital investment, thereby reducing the new Costs can be reduced both when installing air heaters and when rebuilding existing ones.

Claims (6)

a burner with an annular gas collector; a prechamber having a cavity representing a chamber for mixing, ignition and initial combustion of the gas and air streams; A shaftless air heater comprising a chamber for combustion of a gas mixture from a prechamber and a grate refractory brick chamber for passing the generated combustion products,
said prechamber, said combustion chamber, and said grate refractory chamber are interconnected and coaxially positioned, said prechamber and said combustion chamber each having a shell of its own liner, and a shell base of said prechamber; is greater than the diameter of the throat of said dome-shaped combustion chamber shell,
said gas collector presenting an annular channel mounted within a refractory lining of said prechamber forming inner and outer annular walls of said prechamber refractory, said mixing chamber interconnecting with an annular air collector; nozzles for discharge gas and air to the mixing chamber are made in said inner annular wall, said gas and discharge nozzles interconnecting with respective gas and air branches from the outside via said gas and air collectors;
The difference is that the air collector is located in the lower part of the pre-chamber below the gas collector and represents an annular chamber formed by a cavity between the metal annular beam and a base plate, the base plate being the located at the bottom of the pre-chamber and connected to each other and to the shells of the pre-chamber and the combustion chamber,
said metal annular beam forming a pre-chamber support, said base plate having holes for air discharge from said air collector interconnecting with a discharge air nozzle to said mixing chamber through said air supply channel; the latter being located in the inner annular wall below the outlet gas nozzle to the mixing chamber and the air supply channel being located under the refractory lining of the prechamber;
Shaftless air heater. 2. The shaftless air heater of claim 1, wherein the outlet gas nozzles for feeding into the mixing chamber are located at multiple levels of the inner annular wall facing the pre-chamber mixing chamber. Shaftless air heater. 2. The shaftless air heater of claim 1, wherein the nozzle centerline has a downward inclination angle of 15° to 45° with respect to the horizontal plane. 2. The shaftless air heater of claim 1, wherein the centerline of the discharge air nozzle from the gas collector to the mixing chamber has an inclination angle of 0° to 45° with respect to the vertical plane. less air heater. 2. A shaftless air heater as recited in claim 1, wherein said metal annular beam is composed of low alloy steel. 2. The shaftless air heater of claim 1, wherein said metal annular beam has a cross-section in the shape of a right triangle, one side of said right triangle acting as an extension of a prechamber shell, said right triangle A shaftless air heater, the other side of which is formed by said domed combustion chamber shell and whose bottom is represented by said pre-chamber support.

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