Improved structure of reduction chamber of external heating type coal-based direct reduction iron shaft furnace

Abstract

The utility model relates to an improved structure of an external heating type coal-based direct reduction iron shaft furnace reduction chamber, the reduction chamber is divided into a preheating section, a reduction section and a cooling section from top to bottom, the preheating section is provided with a confluence gas channel communicated with an ascending pipe at the furnace top, the top of the reduction chamber is provided with a sealed feed port, and the bottom of the reduction chamber is provided with a sealed discharge port; a plurality of rows of boss structures are arranged on the two side walls of the reduction section in the height direction at intervals, and the boss structures protrude towards the interior of the reduction section. The multiple rows of boss structures are arranged on the reduction section in the height direction, so that materials close to the two side walls can be remixed in the discharging process, material bonding caused by local high temperature is effectively prevented, and the phenomenon that smooth production is affected due to material blocking and the like is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of ironmaking by direct reduction method, in particular to an improved structure of a reduction chamber of an externally heated coal-based direct reduced iron shaft furnace. Background Art

[0002] The chemical composition of direct reduced iron is stable and the impurity content is low. It is a high-quality alternative iron source for scrap steel and a smelting raw material for special steel and high-quality steel. The direct reduction ironmaking process for producing direct reduced iron is divided into a gas-based direct reduced iron process and a coal-based direct reduced iron process. China is a country rich in coal and poor in gas. Natural gas resources are limited and the price is relatively high. Therefore, the coal-based direct reduced iron process is more in line with China's specific national conditions. Among them, the externally heated coal-based shaft furnace process that can produce continuously has the advantages of strong adaptability to raw fuels, good reduction atmosphere, high metallization rate of products, etc., and has become the main equipment for producing direct reduced iron.

[0003] Chinese patent application with the publication number of CN 107893138 A discloses "a reduction chamber of an externally heated coal-based direct reduced iron shaft furnace". The reduction chamber is divided into a preheating section, a reduction section and a cooling section from top to bottom. The preheating section is provided with a converging air duct communicating with the riser pipe at the top of the furnace. The top of the reduction chamber is provided with a sealed feed port, and the bottom of the reduction chamber is provided with a sealed discharge port; the cavity of the reduction chamber is evenly divided into n + 1 holes by n reduction chamber partition walls along the length direction. 2 to 4 gas collecting channels are arranged at both ends and / or inside of each hole of the reduction chamber. The gas collecting channels are communicated with the corresponding reduction chamber through a plurality of gas outlet holes arranged along the height direction; the tops of the gas collecting channels are respectively communicated with the converging air duct, and the bottoms are respectively communicated with the reduction chamber. This reduction chamber has the advantages of good air permeability, no limitation on the particle size of raw coal, good heat transfer conditions, high structural strength, large single-hole production capacity, etc., and can effectively avoid the phenomena of uneven furnace charge descent and material jamming during the production process of direct reduced iron.

[0004] Direct reduced iron is the process of reducing iron oxide to metallic iron at a temperature lower than the melting point of iron. The reduction temperature of direct reduced iron is generally 800 - 1200 °C. When the temperature exceeds 1250 °C, some solid materials will show a semi-molten state, so it is easy to occur adhesion. In the externally heated direct reduced iron shaft furnace, the wall temperature of the reduction chamber is generally less than 1200 °C. However, due to production operations and uneven combustion of the vertical flue gas along the height direction, local high temperatures may occur on the walls of the reduction chamber, resulting in molten adhesion of the materials near the two side walls in the reduction chamber; in addition, during the feeding process of the materials in the reduction chamber, due to the relatively slow descending rate of the solid materials, the relative positions of the materials near the wall of the reduction chamber basically do not change during the descending process, that is, they always remain in the high-temperature area near the wall, accelerating the adhesion process of the solid materials. When the solid materials adhere seriously, it will lead to uneven feeding in the reduction chamber and even material jamming and other phenomena, affecting normal production and even causing production accidents. Summary of the Invention

[0005] The utility model provides an improved structure of a reduction chamber of an externally heated coal-based direct reduced iron shaft furnace. By arranging multiple rows of boss structures along the height direction in the reduction section, the materials near the two side walls can be remixed during the feeding process, effectively preventing the adhesion of materials caused by local high temperature and avoiding phenomena such as material jamming that affect the smooth progress of production.

[0006] In order to achieve the above object, the utility model is realized by adopting the following technical solutions:

[0007] An improved structure of a reduction chamber of an externally heated coal-based direct reduced iron shaft furnace, including a reduction chamber. The reduction chamber is divided into a preheating section, a reduction section and a cooling section from top to bottom. The preheating section is provided with a converging air duct communicating with the riser pipe at the furnace top. The top of the reduction chamber is provided with a sealed feed port, and the bottom of the reduction chamber is provided with a sealed discharge port. The reduction chamber is divided into multiple holes by a reduction chamber partition wall. A plurality of gas collecting channels are arranged at both ends and / or inside each hole of the reduction chamber. The gas collecting channels are communicated with the corresponding reduction chamber through a plurality of gas outlet holes arranged along the height direction. The tops of the gas collecting channels are respectively communicated with the converging air duct, and the bottoms are respectively communicated with the reduction chamber. A plurality of rows of boss structures are arranged at intervals along the height direction on both side walls of the reduction section, and the boss structures protrude towards the inside of the reduction section.

[0008] Further, the cross-sectional shape of the boss structure is triangular, and the included angles between the upper hypotenuse and the lower hypotenuse and the horizontal plane are both greater than the stacking angle of the material; a fillet transition is adopted between the upper hypotenuse and the lower hypotenuse.

[0009] Further, the cross-sectional shape of the boss structure is arc-shaped, and the included angle between the tangent line of the arc in the 45° direction of the horizontal axis and the horizontal plane is greater than the stacking angle of the material.

[0010] Further, the minimum outward convex thickness of the boss structure is 20 mm, and the maximum outward convex thickness is less than 1 / 5 of the inner cavity width of the reduction section.

[0011] Further, the boss structures on both side walls of the reduction section are arranged staggered along the height direction on both side walls of the reduction section.

[0012] Further, the interval distance between the boss structures is greater than the height of the boss structures.

[0013] Further, the boss structure and the side wall of the reduction section are an integral structure.

[0014] Further, the boss structure is arranged longitudinally along the entire length of the inner cavity of the reduction section.

[0015] Compared with the prior art, the beneficial effects of the utility model are:

[0016] By arranging boss structures on both side walls of the reduction section in the reduction chamber, the materials near the side walls of the reduction chamber can be remixed with the internal materials during the feeding process, avoiding the bonding of the materials near the walls due to long-term heating, effectively preventing the bonding of materials caused by local high temperature, and avoiding phenomena such as material jamming that affect the smooth progress of production during the production of sponge iron. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of an improved structure of the reduction chamber of an externally heated coal-based direct reduced iron shaft furnace described in the present invention.

[0018] Figure 2 is a partial enlargement of the boss structure described in the present invention Figure 1 .

[0019] Figure 3 is a partial enlargement of the boss structure described in the present invention Figure 2 .

[0020] Figure 4 is Figure 1 the A-A view in

[0021] Figure 5 is Figure 4 the B-B view in

[0022] In the figure: 1. Combustion chamber 2. Reduction chamber 3. Confluence air duct 4. Sealed feed port 5. Boss structure 6. Sealed discharge port 7. Uptake pipe 11. Upper horizontal air duct 12. Lower horizontal air duct 13. Upright flue 21. Preheating section 22. Reduction section 23. Cooling section 24. Reduction chamber 25. Gas collection channel 26. Reduction chamber partition wall 27. Gas outlet hole DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The following further describes the specific embodiments of the present invention with reference to the drawings:

[0024] See Figure 1 , in the externally heated coal-based direct reduced iron shaft furnace described in the present invention, the reduction chamber 2 is divided into a preheating section 21, a reduction section 22 and a cooling section 23 from top to bottom. A plurality of gas collection channels 25 are arranged at both ends or in the middle of the reduction chamber 2. The preheating section 21 is provided with a confluence air duct 3 communicating with the uptake pipe 7 at the top of the furnace. The top of the gas collection channel 25 communicates with the confluence air duct 3, and the bottom communicates with the reduction chamber 2; a plurality of gas outlet holes 27 arranged along the height direction of the gas collection channel 25 communicate with the reduction chamber 2.

[0025] The improved structure of the utility model mainly sets multiple rows of boss structures 5 along the height direction on the two side walls of the reduction section 22, so that the materials near the two side walls of the reduction section 22 can be remixed with the internal materials during the descending process, avoiding adhesion due to local high temperature in the vertical flue 13 and long-term heating of the materials near the side wall of the reduction section 22. Since the temperatures at the upper horizontal air duct 11 and the lower horizontal air duct 12 are relatively low, the corresponding preheating section 21 and cooling section 23 do not need to be provided with boss structures 5, and only need to be provided in the reduction section 22 corresponding to the vertical flue 13.

[0026] Preferably, as Figure 1 shown, the cross-sectional shape of the boss structure 5 of the utility model is triangular, with one side connected to the side wall of the reduction section 22, and the other two hypotenuses forming the boss structure. The angles between the two hypotenuses and the horizontal plane are greater than the angle of repose of the material, avoiding hanging materials on the upper part of the boss structure 5 or generating voids at the lower part of the boss structure; the intersection of the two hypotenuses is transitioned by a fillet.

[0027] The cross-section of the boss structure 5 of the utility model can also be arc-shaped (as Figure 2 shown), bow-shaped or other smooth curves. It should be noted that the angle between the tangent of the curve at a direction of 45° to the horizontal axis and the horizontal plane should be greater than the angle of repose of the material, also to avoid hanging materials on the upper part of the boss structure 5 and generating voids at the lower part.

[0028] Preferably, as Figure 2 、 Figure 3 shown, the minimum external convex thickness h of the boss structure 5 of the utility model is 20 mm at least, and the maximum external convex thickness is less than 1 / 5 of the inner cavity width of the reduction chamber 2; if the external convex thickness h of the boss structure 5 is too small, it cannot achieve the purpose of remixing the materials, while if the external convex thickness h is too large, it will affect the production capacity of the shaft furnace. The boss structure 5 is arranged longitudinally and transversely throughout the inner cavity 24 of the reduction chamber. The temperature in the gas collection channel 25 is not as high as that in the vertical flue 13, so no boss structure is provided on the corresponding side wall.

[0029] Preferably, the boss structures 5 of the utility model are arranged staggeredly along the height direction on the two side walls of the reduction section 22, and the interval distance L between the boss structures in the same row is not less than the height H of the boss structure 5; ensuring that only one side wall of each horizontal section of the reduction chamber 2 has a boss structure 5, so that the materials can descend in an S-shaped route, avoiding material jamming due to the necking structure; and while ensuring material mixing, it does not affect the production capacity of the reduction chamber 2 as much as possible.

[0030] Preferably, the boss structure 5 of the utility model and the side wall of the reduction section 22 are of an integral structure, that is, the outermost refractory brick of the side wall of the reduction section 22 is an irregular refractory brick, and the boss structure 5 is prefabricated on the side surface of the outer refractory brick, avoiding affecting the strength of the boss structure 5 due to wear of the descending materials.

[0031] To make the objectives, technical solutions, and technical effects of the present utility model clearer, the technical solutions in the embodiments of the present utility model will now be described clearly and completely. However, the embodiments described below are only a part of the embodiments of the present utility model, rather than all of them. Combining the embodiments in the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present utility model.

[0032]

Embodiment 1

[0033] As Figure 1 and Figures 3 - 5 shown, it is an improved structure of the reduction chamber of an externally heated coal-based direct reduced iron shaft furnace in this embodiment. The externally heated coal-based direct reduced iron shaft furnace includes a combustion chamber 1 and a reduction chamber 2. The reduction chamber partition wall 26 of each reduction chamber 2 divides it into two equal holes of the reduction chamber. Gas collection channels 25 are provided at both ends and in the middle of each hole of the reduction chamber. Each hole of the reduction chamber is separated into two reduction chambers 24 by the gas collection channels 25. The top of the gas collection channel 25 is connected to the converging airway 3, and the bottom is connected to the reduction chamber 2. The reduction chamber 2 and the gas collection channel 25 are connected through gas outlet holes 27. The gas collection channel 25 is used to timely export the gas in the reduction chamber 2 to avoid production accidents caused by excessive working pressure in the reduction chamber 2.

[0034] The upper part of the combustion chamber 1 is the upper horizontal airway 11, the middle part is the vertical flue 13, and the lower part is the lower horizontal airway 12, corresponding to the preheating section 21, the reduction section 22, and the cooling section 23 of the reduction chamber 2 respectively. Since the side wall temperature of the reduction section 22 is the highest (up to 800 - 1200 °C), multiple rows of boss structures 5 are only arranged along the height direction on both side walls of the reduction section 22, and no boss structures 5 are arranged in the preheating section 21 and the cooling section 23. In addition, since the gas temperature in the gas collection channel 25 is not high either (generally lower than 800 °C), no boss structures 5 are arranged on the corresponding side walls of the gas collection channel 25.

[0035] In this embodiment, the cross-sectional shape of the boss structure 5 is circular arc-shaped. The angle between the tangent of the circular arc in the direction of 45° from the horizontal axis and the horizontal plane is 55°, while the stacking angle of the charged material is about 40°.

[0036] In this embodiment, the width of the inner cavity (reduction chamber cavity 24) of the reduction section 22 is 300 mm, the outward convex thickness h of the boss structure 5 is 50 mm. The boss structures 5 on both side walls of each reduction chamber 24 are arranged along the longitudinal direction of the reduction chamber cavity 24 throughout. The height of each layer of refractory bricks on the side wall of the reduction section 22 is 125 mm, and the height H of the boss structure 5 is 110 mm. The boss structure 5 and the refractory bricks on the side wall of the reduction section 22 are of an integral structure, centered on the side of the refractory bricks, ensuring that there is no ash joint in the height direction of the boss structure 5 in the reduction chamber 2, and avoiding the falling material from wearing the ash joint and affecting the service life of the boss structure 5.

[0037] In this embodiment, the boss structures 5 on one side wall of the reduction section 22 are arranged on the odd-numbered refractory bricks, and the boss structures 5 on the other side wall are arranged on the even-numbered refractory bricks. The distance L between two adjacent boss structures 5 on the same side wall is 140 mm. Only one side wall of each horizontal section of the reduction section 22 has the boss structure 5, which can ensure the material mixing effect while reducing the impact on the production capacity of the reduction chamber 2.

[0038] During normal production, the mixed raw materials are fed into the reduction chamber 2 from the sealed feed port 4. The combustible gas enters the vertical flue 13 of the combustion chamber 1 to burn, and the generated heat is transferred to the mixed materials in the reduction chamber 2 through the partition wall. As the mixed materials descend, the materials are first preheated by the high-temperature gas in the upper horizontal gas duct 11 in the preheating section 21, and then enter the reduction section 22 to undergo a reduction reaction under high temperature. The coal or semi-coke is gradually consumed, and the pellet ore is gradually reduced to sponge iron, while a large amount of reduction tail gas is generated. The reduction tail gas enters the gas collection channel 25 through the gas outlet hole 27, then flows through the converging gas duct 3 and enters the riser pipe 7, and finally is led out to the gas collecting pipe outside the furnace and enters the reduction tail gas purification system. After all the mixed materials in the reduction section 22 react to form sponge iron and residual carbon, they enter the cooling section 23. In the cooling section 23, internal circulating gas cooling or external circulating cooling water cooling can be adopted. The cooled sponge iron and residual carbon are discharged from the vertical furnace through the sealed discharge port 6.

[0039] In this embodiment, due to the boss structures 5 arranged on both side walls of the reduction section 22, the materials slowly fall in an S-shaped route in the reduction section 22. The materials near the two side walls of the reduction chamber can be remixed with the internal materials during the descending process, avoiding problems such as material adhesion and affecting the smooth production due to the local high temperature of the vertical flue 13 and the long-term heating of the materials near the side wall of the reduction section; the two side boss structures 5 are arranged staggeredly, avoiding problems such as necking structure formation and material jamming in the reduction section 22, ensuring material mixing while minimizing the impact on the production capacity of the reduction chamber 2.

[0040] The embodiments described above are only a part of the embodiments of the present invention, rather than all embodiments. The form of the boss structure can also be other shapes, or arranged on both sides of the reduction chamber in other ways. However, as long as the boss structure is adopted to change the mixing form of the materials and slow down the adhesion of the materials in the reduction chamber, it falls within the protection scope of the present invention.

Claims

1. An improved structure of the reduction chamber of an externally heated coal-based direct reduced iron shaft furnace, including a reduction chamber, the reduction chamber is divided into a preheating section, a reduction section and a cooling section from top to bottom. The preheating section is provided with a converging air duct communicating with the riser pipe at the furnace top. A sealed feed inlet is arranged at the top of the reduction chamber, and a sealed discharge outlet is arranged at the bottom of the reduction chamber; the reduction chamber is divided into multiple holes by a reduction chamber partition wall. A number of gas collecting channels are arranged at both ends and / or inside each hole of the reduction chamber. The gas collecting channels communicate with the corresponding reduction chamber through a plurality of gas outlet holes arranged along the height direction; the tops of the gas collecting channels are respectively communicated with the converging air duct, and the bottoms are respectively communicated with the reduction chamber; characterized in that, On both sides of the reduction section, multiple rows of boss structures are arranged at intervals along the height direction, and the boss structures protrude towards the inside of the reduction section.

2. The improved structure of the reduction chamber of an externally heated coal-based direct reduced iron shaft furnace according to claim 1, characterized in that, The cross-sectional shape of the boss structure is triangular, and the angles between the upper hypotenuse and the lower hypotenuse and the horizontal plane are both greater than the angle of repose of the material; a fillet transition is adopted between the upper hypotenuse and the lower hypotenuse.

3. The improved structure of the reduction chamber of an externally heated coal-based direct reduced iron shaft furnace according to claim 1, characterized in that, The cross-sectional shape of the boss structure is arc-shaped, and the angle between the tangent line of the arc in the 45° direction of the horizontal axis and the horizontal plane is greater than the angle of repose of the material.

4. An improved structure of a reduction chamber of an externally heated coal-based direct reduced iron shaft furnace according to claim 1, characterized in that, The minimum outer convex thickness of the boss structure is 20 mm, and the maximum outer convex thickness is less than 1 / 5 of the inner cavity width of the reduction section.

5. The improved structure of the reduction chamber of an externally heated coal-based direct reduced iron shaft furnace according to claim 1, characterized in that, The boss structures on both sides of the reduction section are arranged staggeredly along the height direction on both sides of the reduction section wall.

6. The improved structure of the reduction chamber of an externally heated coal-based direct reduced iron shaft furnace according to claim 1, characterized in that, The spacing distance of the boss structures is greater than the height of the boss structures.

7. An improved structure of a reduction chamber of an externally heated coal-based direct reduced iron shaft furnace according to claim 1, characterized in that, The boss structure and the side wall of the reduction section are an integral structure.

8. The improved structure of the reduction chamber of an externally heated coal-based direct reduced iron shaft furnace according to claim 1, characterized in that, The boss structure is arranged longitudinally throughout the inner cavity length of the reduction section.

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