RU2316600C2 - Air heater - Google Patents

Abstract

FIELD: metallurgy, namely constructions of air heaters of blast furnaces.

SUBSTANCE: apparatus includes casing with lining; adapter; roof with pre-combustion chamber coaxially arranged in its upper portion and having jacket and lining separately rested upon casing; ducts for passing air and gas are formed in lateral vertical wall of pre-combustion chamber lining and they are communicated with inner collectors and unions for supplying gas and air. Ducts of lower collector are arranged in its upper portion and they are directed upwards from horizontal plane by inclination angle 15 - 30°. Ducts of upper collector are arranged in its lower portion and they are directed downwards from horizontal plane by inclination angle 15 - 30°. Projections of axes of all ducts on horizontal plane form angle 15 - 45° relative to projections on horizontal plane of radiuses of pre-combustion chambers passing through centers of outlet cross sections of said ducts.

EFFECT: lowered operational expenses, improved quality of gas burning.

2 dwg

Description

The invention relates to the field of ferrous metallurgy, in particular to the design of apparatus for heating air blast blast furnaces.

Known air heaters without a combustion chamber (shaftless) with the installation of burner devices or pre-chambers on the dome of the air heater (Russian patent No. 2145637, AS No. 602555, Japanese patent No. 48-4284, US patent No. 3473794), which are more promising devices.

Closest to the proposed invention according to the technical nature and combination of features is shaftless air heater according to Russian patent No. 2145637, class. C21B 9/02 (prototype). It has a casing with a lining, a nozzle, a dome, a hot blast fitting located above the nozzle at a distance to its axis of at least one diameter of its passage section, as well as a prechamber located in the upper part of the dome coaxially with it and having a casing with a lining made independently from the lining of the dome with independent support on the casing of the prechamber. In the prechamber, there are annular gas and air manifolds that are located between the casing and the side wall of the prechamber lining one above the other and are separated by a partition. The collectors have supply fittings and output channels, the latter being made in the vertical side wall of the lining of the prechamber and the gas and air exit directly into the prechamber. Due to the fact that the axis of the channels of the upper row from the lower collector are directed to the axis of the prechamber and are shifted upward from the horizontal plane by an angle of up to 30 °, and the axes of all other channels are located in the horizontal plane and directed at an angle of 15 ÷ 30 ° to the radii of the prechamber through the centers of their outlet sections, swirling flows of gas and air are formed in the prechamber. The swirling of the flows ensures complete burnout of the gas before entering the nozzle and uniform distribution of the flow over the nozzle.

Blast furnace heaters are large-sized high-temperature apparatuses and require large expenses for their construction and operation. Therefore, one of the main requirements for them is to reduce energy costs. In addition, air heaters burn a large amount of blast furnace gas, which includes carbon monoxide poisonous gas CO. Therefore, an important requirement in the operation of blast furnaces is the complete combustion of gas, which will ensure their environmental safety.

In connection with the above, a known air heater has several disadvantages.

To ensure good mixing and combustion of gas and air in their chamber, their swirling flows are created. Gas enters the upper part of the prechamber and a swirling gas flow forms here. To enable good mixing of gas and air in the known heater, it is provided that the axes of the air channels of the upper row from the lower collector are directed towards the axis of the prechambers and offset upwards from the horizontal plane by an angle of up to 30 °. It is assumed that the directed along the radius and upward displaced air jets must pass through the gas flow to the central part of the prechamber and ensure good mixing and combustion of gas in the center of the prechamber. The air jets from the channels of the remaining rows are directed at an angle to the radii of the prechamber and should provide good mixing and combustion of peripheral gas flows. However, for air heaters of large blast furnaces, the pre-chambers have large transverse dimensions and to pass to the axis of the pre-chambers the air jets must overcome the swirling flow of gas of considerable thickness. For this, it is necessary to significantly increase their speeds and install more powerful air blowers, which will increase energy costs. In addition, incomplete combustion of gas may occur in the central part of the prechamber, which will lead to a deterioration in the environmental performance of air heaters. In this case, a contradiction arises. On the one hand, to increase the penetrating power of the upper row air jets, it is necessary to significantly increase their speed and, consequently, the pressure in the manifold, which will require the use of much more powerful air blowers. On the other hand, for air jets from the channels of the remaining rows, an increase in speeds is not required, since in the peripheral sections of the prechamber and at normal speeds and swirling flows, good mixing and complete combustion of gas before entering the nozzle is ensured.

Thus, for channels of different rows exiting one collector, different pressures in this collector are required, which is impossible to provide. Since superchargers with conventional heads are installed in the manifold to ensure air pressure, the speed of the jets from the channels of the upper row is insufficient and the amount of air that is required for complete gas combustion does not enter the center of the prechamber. As a result of this, part of the gas does not burn and is released into the atmosphere, which affects the environmental characteristics of the air heater.

The basis of the present invention is the task of reducing operating costs and improving gas combustion achieved by redistributing the flow of gas and air in the prechamber.

The solution to this problem is achieved by the fact that in accordance with the invention in a known air heater containing a casing with a lining, a nozzle, a dome, a hot blast fitting located above the nozzle at a distance from its axis at least one diameter of its passage section, a prechamber located coaxially in the upper part of the dome with it and having a casing with a lining made independently of the lining of the dome with independent support on the casing of the prechamber, gas and air manifolds with a partition between them, located between the casing and laterally the chamber walls of the prechamber lining one above the other and having supply fittings and output channels made in the vertical side wall of the prechamber lining, the channel axes from the lower collector are located in the upper part of the collector and are directed upward from the horizontal plane at an angle of 15–30 °, and the channel axes are from the upper the collectors are located in the lower part of the collector and are directed downward from the horizontal plane at an angle of 15–30 °, and the projections of the axes of all channels on the horizontal plane form an angle of 15–45 ° to the projections on the horizontal plane the velocity of the radii of the prechambers passing through the centers of the outlet sections of the channels.

The execution in the prechamber of the channels from the lower manifold located in its upper part and directed upward at an angle of 15–30 °, and the channels from the upper collector located below and directed downward at an angle of 15–30 °, allows directing gas and air jets towards each other so that in the future they can move in one satellite stream, introducing themselves into each other. Air jets do not need to overcome the swirling gas flow of large thickness in order to get to the center of the prechamber, because they get there with jets of gas. High air jets and high-pressure air blowers are also not required. The location of the projections of the axes of all channels on the horizontal plane at an angle of 15 ÷ 45 ° to the projections on the horizontal plane of the radii of the prechambers passing through the centers of their output sections allows you to create the necessary high degree of swirling gas and air jets leaving the channels, which provides, on the one hand , complete combustion of gas before entering the nozzle and, on the other hand, uniform flow inlet into the nozzle. As a result of such a constructive implementation of blast furnaces of both small and large volumes on air heaters, gas is completely burned to the nozzle entrance and the combustion products enter the nozzle uniformly while reducing energy costs while providing environmentally friendly combustion products.

The invention is illustrated graphic materials, which presents:

figure 1 is a General view of one of the possible embodiments of a shaftless air heater of the proposed design, a vertical section, where the fittings for supplying gas and air and the hot blast fitting are conventionally combined in one plane;

figure 2 - section I-I in figure 1.

The heater includes a casing 1 with a lining 2, a nozzle 3, a hot blast fitting 4, a dome 5 with a pre-chamber 6 located in its upper part, having a casing 7 and a lining 8, made independently of the lining of the dome with independent support 9 on the casing. The nozzle of the hot blast 4 is located above the nozzle 3 at a distance to its axis of at least 1 diameter of its passage section. In the vertical wall of the prechamber, channels are made for the passage of gas 11 and air 12 with a partition 13 between them, communicating with internal collectors 14 and 15 and fittings 16 and 17 for supplying gas and air. The axis of the channels 12 from the lower collector 15 are located in the upper part of the collector and are directed upward from the horizontal plane at an angle α = 15–30 °. The axis of the channels 11 from the upper collector 14 are located in the lower part of the collector and are directed downward from the horizontal plane at an angle β = 15–30 °. The projections of all channels on the horizontal plane form an angle of φ = 15 ÷ 45 ° to the projections on the horizontal plane of the radii of the prechambers passing through the centers of the output sections of the channels.

Preferably, gas is supplied to the upper collector and air to the lower collector, as shown in FIG. However, the feed may be the opposite.

The described air heater contains significant differences and works as follows.

During the heating period of the nozzle, combustion air through the nozzle 17 is supplied to the air collector 15 located inside the air heater between the casing and the pre-chamber lining under the gas manifold 14, and through the channels 12 in the vertical wall of the lining 10 enters the pre-chamber. The air jets from the channels 12 are directed upwards. Gas through the pipe 16 is supplied to the gas manifold 14 located inside the air heater between the casing and the lining of the prechamber over the air collector 17, from where it enters the prechamber through the channels 11 located in the vertical wall 10 of the lining. The jets of gas from the channels 11 are directed downward, towards the jets of air.

As a result, there is a mutual introduction of gas jets into air jets and joint movement of gas and air in one satellite stream from the periphery of the prechamber to the center. Air is no longer required to overcome the swirling flow of gas of considerable thickness, and it moves with the gas flow towards the center of the prechamber. The exit of both flows from the channels located at an angle φ = 15–45 ° to the radii of the prechamber creates a swirl of flows in one direction, which further improves the mixing of gas and air. When gas and air flows merge, the air-gas mixture ignites from the pre-heated pre-chamber masonry. Intensive mixing of gas and air in a single swirling flow leads to rapid combustion of gas, which begins in the prechamber and ends at the entrance to the conical part of the dome.

In the blasting period, the cold blast enters the nozzle 3 from below and, passing its top, heats up. The heated blast leaves under the dome 5 and is discharged through the hot blast fitting 4 to the consumer, for example, into a blast furnace. During the blasting period, due to the high temperature of the hot blasting, in the prechamber, the masonry temperature is maintained sufficient to burn the mixture of gas and air at the beginning of the gas period.

Thus, due to the fact that intense mixing and burning of gas and air is organized in the prechamber during the gas period, the jets of which move in a spiral swirling flow, complete combustion of gas is achieved before entering the nozzle while reducing energy costs while ensuring environmentally friendly combustion products on blast furnace air heaters both small and large volume.

The invention can be used not only in ferrous metallurgy for heating blast furnaces, but also in the energy sector for heating a coolant (air, gas) to high temperatures.

Claims (1)

An air heater comprising a casing with a lining, a nozzle, a dome, a hot blast fitting located above the nozzle at a distance to its axis of at least one diameter of its passage section, a pre-chamber located in the upper part of the dome coaxially with it and having a casing with a lining made independently of lining of the dome with independent support on the cover of the prechamber, gas and air manifolds with a partition between them, located between the casing and the side wall of the lining of the prechamber one above the other and having inlet fittings and output channels made in the vertical side wall of the lining of the prechamber, characterized in that the output channels of the lower collector are located in its upper part and are directed upward from the horizontal plane at an angle of 15-30 °, and the output channels of the upper collector are located in its lower part and directed down from the horizontal plane at an angle of 15 ÷ 30 °, and the projections of the axes of these channels on the horizontal plane form an angle of 15 ÷ 45 ° to the projections on the horizontal plane of the radii of the prechamber passing through the centers of the weekend cheny channels.

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