A burner for magnetized roasting rotary kiln

Abstract

The present invention discloses a burner for a magnetized roasting rotary kiln, comprising a coarse coal powder supply channel, a coarse coal powder conveying air channel, a primary combustion-supporting air supply channel, a fine coal powder supply channel, and a fine coal powder conveying air channel. The primary combustion-supporting air supply channel is interspaced and sleeved on the outside of the coarse coal powder supply channel, the fine coal powder supply channel is interspaced and sleeved on the outside of the primary combustion-supporting air supply channel, the output end of the coarse coal powder conveying air channel is arranged in the conveying direction of the coarse coal powder, and the output end of the fine coal powder conveying air channel is arranged in the conveying direction of the fine coal powder. The present invention can form a reasonable temperature field, and at the same time, the temperature field control is more flexible and convenient, further reducing the problem of local excessive temperature and the generation of more thermal NOx gas, making the combustion and reduction process more green and environmentally friendly.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgy and mineral processing equipment, and in particular relates to a burner for a magnetized roasting rotary kiln. Background Art

[0002] As a key component in the high-temperature phase transformation process of ferrous metals, burner performance directly impacts roasting fuel usage, product quality, production output, and the lifespan of refractory materials. The design philosophy for burners used in conventional metallurgical equipment is to achieve a relatively optimal flame temperature distribution and length within the reactor by adjusting the equipment structure and the ratio of primary to secondary air to enhance high-temperature gas recirculation.

[0003] However, in the pursuit of a high fuel burnout rate, the reducing gas concentration distribution in the radial direction of the reactor has been largely ignored. Furthermore, because different fuel sizes require different times for complete combustion, the controllable range of the reducing atmosphere concentration distribution in the radial direction of the reactor by adjusting the excess air coefficient alone is relatively small, and the radial reducing medium concentration distribution decreases in a single outward gradient direction. This has an adverse effect on roasting processes that require controlled reaction atmospheres, such as the reduction roasting of weakly magnetic iron ore and pyrolusite.

[0004] Furthermore, if the temperature field distribution formed after the burner combustion is unreasonable, causing the local peak temperature to be too high, it will lead to the "ringing" problem during the industrial operation of the magnetized roasting rotary kiln. When the rings cannot fall off automatically, the kiln must be stopped for processing, resulting in a decrease in the operating rate of the rotary kiln.

[0005] Specifically, when the fuel burns, the N2 in the combustion-supporting gas will undergo a Zeldovich reaction at high temperature:

[0006]

[0007] When the roasting temperature is below 1500°C, the amount of nitrogen oxides produced is minimal. As the reaction temperature increases, the reaction rate of the Zeldovich reaction increases exponentially, particularly at roasting temperatures above 1500°C, where the reaction rate increases 6-7 times for every 100°C increase in temperature. Conventional burners used in metallurgical equipment typically optimize the premixing of fuel and combustion gas to achieve high fuel burnout rates, largely ignoring the environmental pollution caused by the generation of large amounts of thermal nitrogen oxides at excessively high temperatures. However, phase transformation processes such as magnetization roasting of weakly magnetic iron ore and reduction roasting of pyrolusite require relatively low temperatures of 650°C to 850°C. Excessively high temperatures can easily trigger side reactions and environmental pollution, while lower temperatures can slow the reaction or even prevent it from occurring. Summary of the Invention

[0008] The object of the present invention is to provide a burner for a magnetized roasting rotary kiln, thereby solving the above-mentioned problems.

[0009] To achieve the above-mentioned purpose, the present invention discloses a burner for a magnetized roasting rotary kiln, comprising a coarse-grained coal powder supply channel, a coarse-grained coal powder conveying air channel, a primary combustion-supporting air supply channel, a fine-grained coal powder supply channel and a fine-grained coal powder conveying air channel, wherein the primary combustion-supporting air supply channel is gap-sleeved on the outside of the coarse-grained coal powder supply channel, the fine-grained coal powder supply channel is gap-sleeved on the outside of the primary combustion-supporting air supply channel, the output end gap of the coarse-grained coal powder conveying air channel is gap-inserted into the input end of the coarse-grained coal powder supply channel and is arranged in the conveying direction of the coarse-grained coal powder, and the output end of the fine-grained coal powder conveying air channel is gap-inserted into the input end of the fine-grained coal powder supply channel and is arranged in the conveying direction of the fine-grained coal powder.

[0010] Furthermore, it also includes a secondary combustion-supporting air supply channel, and the secondary combustion-supporting air supply channel is sleeved on the outside of the fine-grained coal powder supply channel.

[0011] Furthermore, the fine-grained coal powder conveying air channel includes a fine-grained coal powder conveying air straight pipe and a fine-grained coal powder conveying air sleeve that are arranged to intersect each other. The fine-grained coal powder conveying air sleeve is sleeved on the outside of the primary combustion air supply channel, and the input end of the fine-grained coal powder conveying air straight pipe is installed with a fine-grained coal powder conveying air straight pipe flange.

[0012] Furthermore, the fine-grained coal powder supply channel includes a fine-grained coal powder supply sleeve, a fine-grained coal powder supply gradually expanding tube and a fine-grained coal powder supply straight pipe. The gap of the secondary combustion air supply channel is sleeved on the outside of the fine-grained coal powder supply sleeve. The fine-grained coal powder supply gradually expanding tube is coaxially connected to the fine-grained coal powder supply sleeve. One end of the fine-grained coal powder supply straight pipe is connected to the side wall of the fine-grained coal powder supply gradually expanding tube, and the other end is equipped with a fine-grained coal powder supply straight pipe flange.

[0013] Furthermore, the output end of the fine coal powder supply straight pipe is arranged toward the output end of the fine coal powder conveying air casing.

[0014] Furthermore, the secondary combustion air supply channel includes a secondary combustion air supply straight pipe and a secondary combustion air supply sleeve arranged to intersect each other, the secondary combustion air supply sleeve gap is sleeved on the outside of the fine coal powder supply sleeve, and the input end of the secondary combustion air supply straight pipe is installed with a secondary combustion air supply straight pipe flange.

[0015] Furthermore, the primary combustion air supply channel includes a primary combustion air supply straight pipe and a primary combustion air supply sleeve that are arranged to intersect each other. The primary combustion air supply sleeve is gap-sleeved on the outside of the coarse-grained coal powder supply channel, and a primary combustion air supply straight pipe flange is installed at the input end of the primary combustion air supply straight pipe.

[0016] Furthermore, the coarse-grained coal powder supply channel includes a coarse-grained coal powder supply elbow, a coarse-grained coal powder supply straight pipe connected to both ends of the coarse-grained coal powder supply elbow, and a coarse-grained coal powder supply center pipe. The primary combustion air supply sleeve is gap-sleeved on the outside of the coarse-grained coal powder supply center pipe. A coarse-grained coal powder supply straight pipe flange is installed at the input end of the coarse-grained coal powder supply straight pipe. The coarse-grained coal powder conveying air channel includes a coarse-grained coal powder conveying air straight pipe inserted into the coarse-grained coal powder supply elbow, and a coarse-grained coal powder conveying air flange is provided at the end of the coarse-grained coal powder conveying air straight pipe.

[0017] Furthermore, the coarse-grained coal powder conveying air straight pipe is coaxially arranged with the coarse-grained coal powder supply central pipe.

[0018] Furthermore, the output ends of the coarse-grained coal powder supply channel, the primary combustion-supporting air supply channel, the fine-grained coal powder supply channel and the secondary combustion-supporting air supply channel are coaxially arranged, and the edges of the output ends of the coarse-grained coal powder supply channel, the primary combustion-supporting air supply channel, the fine-grained coal powder supply channel and the secondary combustion-supporting air supply channel are flush.

[0019] Compared with the prior art, the advantages of the present invention are:

[0020] 1. The burner of the present invention pre-divides the pulverized coal into two particle sizes: coarse pulverized coal and fine pulverized coal. The coarse pulverized coal is ejected at a longer distance by the high-speed wind, and an incomplete combustion reaction occurs in the middle and rear areas of the reactor. At the same time, because the particle size of this part of the coal is coarse, it takes a long time for complete combustion, and an incomplete combustion reaction gradually occurs from the middle and rear areas of the reactor, which is conducive to forming a reasonable atmosphere field. The fine coal has a smaller mass, and under the driving effect of the conveying wind, an incomplete combustion reaction occurs in the area near the kiln head of the reactor, generating a large amount of heat and a reducing atmosphere. By adjusting the conveying wind speed and air volume, the combustion of coal of different particle sizes in different areas of the reactor can be controlled, and the temperature field and atmosphere field in the reactor can be more flexibly and conveniently regulated. Furthermore, the scouring of the inner wall of the reactor by the blowing process can be reduced, and the service life and life of the refractory materials in the reactor can be extended.

[0021] 2. The outermost part of the burner of the present invention is a fine-grained coal powder channel, which can avoid the reduction of the reducing medium concentration in the reactor in a single gradient direction radially outward, and can flexibly adjust the radial reducing atmosphere concentration distribution in the reactor so that a strong reducing atmosphere is still maintained near the reaction material layer.

[0022] 3. The burner of the present invention can make the combustion reaction of coarse coal milder and the time required for complete combustion longer, while the combustion reaction of fine coal is relatively violent and the time required for complete combustion is relatively shorter. According to this fuel combustion reaction characteristic, the coarse particles are controlled to burn in the middle and rear areas of the kiln while the fine particles are controlled to burn in the area closer to the kiln head. This can reduce the problem of local excessive temperature and more thermal NOx gas generated by the superposition of heat released by the combustion of coarse coal and fine coal, making the combustion and reduction process more green and environmentally friendly.

[0023] 4. The present invention can control the combustion of coal in different areas of the reactor and the intensity of the combustion reaction by adjusting the conveying wind speed and air volume, and the ratio of primary combustion-supporting air to secondary combustion-supporting air, thereby making the temperature field control in the reactor more flexible and convenient.

[0024] The present invention will be described in further detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0026] Figure 1 This is a schematic structural diagram of a burner used in the magnetized roasting rotary kiln in the first embodiment of the present invention;

[0027] Figure 2 This is the CO concentration distribution at 10m from the kiln head after combustion in a φ4m×50m rotary kiln without adding any material in Example 1 of the present invention;

[0028] Figure 3 This is the CO concentration distribution at 10m from the kiln head when the burner of Example 1 of the present invention is burned in a φ4m×50m rotary kiln and charged;

[0029] Figure 4 Schematic diagram of the burner structure of the magnetized roasting rotary kiln in the second embodiment of the present invention;

[0030] Figure 5 The temperature field distribution at different positions in a φ4m×50m rotary kiln is compared when the burner of Example 2 of the present invention and a conventional burner are used in operation.

[0031] Legend:

[0032] 1. Coarse coal powder conveying air channel; 11. Coarse coal powder conveying air straight pipe; 12. Coarse coal powder conveying air flange;

[0033] 2. Coarse coal powder supply channel; 21. Coarse coal powder supply elbow; 22. Coarse coal powder supply straight pipe; 23. Coarse coal powder supply center pipe; 24. Coarse coal powder supply straight pipe flange;

[0034] 3. Primary combustion air supply channel; 31. Primary combustion air supply straight pipe; 32. Primary combustion air supply casing; 33. Primary combustion air supply straight pipe flange;

[0035] 4. Fine coal powder supply channel; 41. Fine coal powder supply casing; 42. Fine coal powder supply gradually expanding pipe; 43. Fine coal powder supply straight pipe; 44. Fine coal powder supply straight pipe flange;

[0036] 5. Fine-grained coal conveying air channel; 51. Fine-grained coal conveying air straight pipe; 52. Fine-grained coal conveying air casing; 53. Fine-grained coal conveying air straight pipe flange;

[0037] 6. Secondary combustion air supply channel; 61. Secondary combustion air supply straight pipe; 62. Secondary combustion air supply casing; 63. Secondary combustion air supply straight pipe flange. DETAILED DESCRIPTION

[0038] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered by the claims.

[0039] Example 1:

[0040] like Figure 1-3 As shown, the present invention discloses a burner for a magnetized roasting rotary kiln. The burner comprises a coarse coal supply channel 2, a coarse coal conveying air channel 1, a primary combustion air supply channel 3, a fine coal supply channel 4, and a fine coal conveying air channel 5. All of the burners are formed using circular pipes and arranged in a sleeved configuration. The sleeved pipes are separated by high-temperature resistant steel and are coaxially arranged. The outlets of the coarse coal conveying air channel 1, the primary combustion air supply channel 3, and the fine coal supply channel 4 are aligned. The primary combustion air supply channel 3 is gap-jacketed on the outside of the coarse-grained coal powder supply channel 2, and the fine-grained coal powder supply channel 4 is gap-jacketed on the outside of the primary combustion air supply channel 3. The output end of the coarse-grained coal powder conveying air channel 1 is gap-jacketed in the input end of the coarse-grained coal powder supply channel 2 and is arranged in the conveying direction of the coarse-grained coal powder. Thus, the coarse-grained coal powder in the coarse-grained coal powder supply channel 2 is fed into the reactor at a high speed through the jetting effect of the coarse-grained coal powder conveying air channel 1, and the output end of the fine-grained coal powder conveying air channel 5 is plugged into the input end of the fine-grained coal powder supply channel 4 and is arranged in the conveying direction of the fine-grained coal powder. Similarly, the coarse-grained coal powder in the fine-grained coal powder supply channel 4 is fed into the reactor at a high speed through the jetting effect of the fine-grained coal powder conveying air channel 5.

[0041] Specifically, the fine coal powder supply channel 4 includes a fine coal powder supply sleeve 41, a fine coal powder supply gradually expanding pipe 42 and a fine coal powder supply straight pipe 43. The fine coal powder supply gradually expanding pipe 42 is coaxially connected to the fine coal powder supply sleeve 41. One end of the fine coal powder supply straight pipe 43 is connected to the side wall of the fine coal powder supply gradually expanding pipe 42, and the other end is equipped with a fine coal powder supply straight pipe flange 44, so as to facilitate connection with an external fine coal powder storage device. The injection amount of fine coal powder is reasonably adjusted according to the amount of fuel required for the reaction and the amount of coarse coal powder that has been injected. The fine coal powder conveying air channel 5 includes a fine coal powder conveying air straight pipe 51 and a fine coal powder conveying air sleeve 52 arranged with axes perpendicular to each other. The fine coal powder conveying The air sleeve 52 is sleeved on the outside of the primary combustion-supporting air supply channel 3, and the input end of the fine-grained coal powder conveying air straight pipe 51 is installed with a fine-grained coal powder conveying air straight pipe flange 53, which is connected to the external air storage device through the fine-grained coal powder conveying air straight pipe flange 53. The fine-grained coal powder conveying air volume is reasonably adjusted according to the fine-grained coal powder injection amount, and the fine-grained coal powder is fed into the reactor at a high speed through the injection effect of the fine-grained coal powder conveying gas to maintain the reducing atmosphere field in the head area of ​​the reactor. At the same time, because the outermost periphery of the burner is the fuel injection area, the concentration of the reducing medium in the reactor can be avoided from decreasing in a single gradient direction in the radial outward direction, thereby creating good reducing atmosphere conditions for reactions such as the reduction roasting of weakly magnetic iron ore and pyrolusite.

[0042] In this embodiment, the output end of the fine-grained coal powder supply straight pipe 43 is arranged toward the output end of the fine-grained coal powder conveying air sleeve 52, so that the falling material of the fine-grained coal powder supply straight pipe 43 can be output evenly through the annular conveying air of the fine-grained coal powder conveying air sleeve 52, thereby improving the conveying efficiency and preventing accumulation in the fine-grained coal powder supply gradually expanding pipe 42.

[0043] In this embodiment, the primary combustion-supporting air supply channel 3 comprises an intersecting primary combustion-supporting air supply straight pipe 31 and a primary combustion-supporting air supply sleeve 32. The primary combustion-supporting air supply sleeve 32 is interstitially sleeved on the outside of the coarse-grained coal supply channel 2. A primary combustion-supporting air supply straight pipe flange 33 is mounted on the input end of the primary combustion-supporting air supply straight pipe 31. The primary combustion-supporting air supply straight pipe flange 33 is connected to an external gas storage device. During operation, the combustion-supporting air volume is appropriately adjusted based on the temperature distribution within the kiln and the amount of coarse-grained coal injected, maintaining a reducing atmosphere in the center and rear of the reactor.

[0044] In this embodiment, the coarse coal powder supply channel 2 includes a coarse coal powder supply elbow 21 and a coarse coal powder supply straight pipe 22 connected to both ends of the coarse coal powder supply elbow 21, and a coarse coal powder supply center pipe 23. The primary combustion air supply sleeve 32 is sleeved on the outside of the coarse coal powder supply center pipe 23. The input end of the coarse coal powder supply straight pipe 22 is installed with a coarse coal powder supply straight pipe flange 24. The coarse coal powder conveying air channel 1 includes a coarse coal powder supply elbow 21 and a coarse coal powder supply straight pipe 22. The coarse coal pulverized air supply straight pipe 11 is located within the pulverized coal supply elbow 21. A coarse coal pulverized air supply flange 12 is provided at the end of the coarse coal pulverized air supply straight pipe 11. The configuration of the coarse coal pulverized air supply elbow 21 provides space for the insertion of the coarse coal pulverized air supply straight pipe 11. Simultaneously, the coarse coal pulverized air supply flange 12 is connected to an external air storage device via a pipeline. The combustion-supporting air volume is appropriately adjusted based on the amount of coarse coal pulverized air injected, maintaining a uniform temperature field in the center and rear of the reactor. In a specific configuration, the coarse coal pulverized air supply straight pipe 11 is coaxially arranged with the coarse coal pulverized air supply central pipe 23, thereby enhancing the injection and entrainment effect of the coarse coal pulverized air supply straight pipe 11. Under the injection and entrainment effect of the coarse coal conveying air, the coarse coal pulverized air is injected into the reactor at high speed through the coarse coal pulverized air supply central pipe 23. Driven by high-speed conveying wind, this part of coarse coal is sprayed to the middle and rear area of ​​the reactor, and a combustion reaction occurs in this area, providing the required heat to maintain the ideal temperature field in the middle and rear parts of the reactor. At the same time, because the particle size of this part of coal powder is coarser, it takes relatively longer time for complete combustion. The gradual combustion reaction from the middle and rear parts of the reactor is conducive to forming a uniform temperature field.

[0045] At the same time, the pulverized coal is pre-classified into two particle sizes: coarse-grained pulverized coal and fine-grained pulverized coal. These are then injected into the reactor using different conveying wind speeds and air volumes, with combustion reactions occurring in different areas of the reactor. The coarse-grained pulverized coal requires a higher injection velocity, which is injected via the burner's coarse-grained pulverized coal supply central tube 23. The fine-grained pulverized coal requires a lower injection velocity, which can be supplemented secondaryally by the burner's outermost layer. This allows for the rational regulation of the spatial distribution of the temperature field within the reactor and reduces erosion of the reactor's inner wall during the injection process, extending the service life and lifespan of the refractory materials within the reactor.

[0046] In this embodiment, the output ends of the coarse-grained coal powder supply channel 2, the primary combustion-supporting air supply channel 3 and the fine-grained coal powder supply channel 4 are coaxially arranged, and the edges of the output ends of the coarse-grained coal powder supply channel 2, the primary combustion-supporting air supply channel 3 and the fine-grained coal powder supply channel 4 are arranged flush, so that the combustion at the burner output end is more uniform and stable.

[0047] Furthermore, in this embodiment, the burner is installed on a φ4m×50m rotary kiln, and the physical and chemical parameters of the coal are shown in Table 1:

[0048] Table 1 Analysis results of physical and chemical parameters of coal

[0049] Ash content (%) Volatile matter (%) Ignition temperature ℃ Fixed carbon (%) Calorific value (kcal / kg) Sulfur content (%) 8 34.66 369 54.58 7687.4 / 6843 0.37

[0050] The coal is finely ground by Raymond mill + hot air drying + wind conveying and then classified into +0.15mm coarse coal powder and -0.15mm fine coal powder and stored in suitable silos. After the radial atmosphere controllable burner of the present invention is used for coal injection combustion, the CO concentration distribution at 10m away from the kiln head in the rotary kiln is as follows: Figure 2 shown.

[0051] from Figure 2 The results show that after combustion with the burner of the present invention, the radial CO concentration at a distance of 10 m from the kiln head is approximately in an "M" shape distribution. Compared with the radial CO concentration after combustion with the conventional burner, the CO concentration at the center of the burner of the present invention is lower and the CO concentration near the kiln wall is higher, which is consistent with the atmosphere requirements for material reaction.

[0052] Furthermore, the burner was installed on the aforementioned φ4m×50m rotary kiln. The physical and chemical parameters of the coal used remained unchanged. The feed rate into the rotary kiln was 45-50t / h, and the corresponding pulverized coal injection rate was 35-40kg / t. 给矿 The radial concentration distribution of CO at a distance of 10m from the rotary kiln head is as follows: Figure 3 shown.

[0053] from Figure 3 The results show that compared with the radial CO concentration distribution after combustion with a conventional burner, the CO concentration in the area near the material layer after combustion with the burner described in the present invention is higher, while the CO concentration in the upper area of ​​the kiln is lower, maintaining a relatively ideal spatial distribution of the magnetic roasting reduction field of weakly magnetic iron ore.

[0054] Example 2:

[0055] like Figure 4-5 As shown, the present invention discloses a burner for a magnetized roasting rotary kiln, the main structure of which is similar to that of the first embodiment, except that it further includes a secondary combustion-supporting air supply channel 6, wherein the secondary combustion-supporting air supply channel 6 is coaxially sleeved on the outside of the fine-particle coal powder supply channel 4 with a gap, and its output port is aligned with the output ports of the coarse-particle coal powder supply channel 2, the primary combustion-supporting air supply channel 3, and the fine-particle coal powder supply channel 4. Thus, the coarse-particle coal powder in the coarse-particle coal powder supply channel 2 is fed into the reaction furnace at a high speed through the jet-injection effect of the coarse-particle coal powder conveying air channel 1, and the output end of the fine-particle coal powder conveying air channel 5 is plugged into the input end of the fine-particle coal powder supply channel 4 and is arranged in the conveying direction of the fine-particle coal powder. Similarly, the coarse-particle coal powder in the fine-particle coal powder supply channel 4 is fed into the reaction furnace at a high speed through the jet-injection effect of the fine-particle coal powder conveying air channel 5.

[0056] In this embodiment, the secondary combustion air supply channel 6 includes a secondary combustion air supply straight pipe 61 and a secondary combustion air supply sleeve 62 that are intersectingly arranged, the secondary combustion air supply sleeve 62 is gap-jacketed on the outside of the fine-grained coal powder supply sleeve 41, and the input end of the secondary combustion air supply straight pipe 61 is equipped with a secondary combustion air supply straight pipe flange 63, and the primary combustion air supply channel 3 includes a primary combustion air supply straight pipe 31 and a primary combustion air supply sleeve 32 that are intersectingly arranged, the primary combustion air supply sleeve 32 is gap-jacketed on the outside of the coarse-grained coal powder supply channel 2, and the input end of the primary combustion air supply straight pipe 31 is equipped with a primary combustion air supply straight pipe flange 33. Connected to an external gas storage device via the primary combustion air supply straight pipe flange 33 and the secondary combustion air supply straight pipe flange 63, the primary and secondary combustion air volumes are appropriately adjusted based on the temperature distribution within the kiln and the total amount of fuel injected, maintaining a uniform temperature field in the front and center of the reactor. Simultaneously, the secondary air volume is appropriately supplemented based on the temperature distribution within the kiln resulting from the combustion of coarse and fine pulverized coal. This avoids the problems of excessively high local temperatures and shortened high-temperature zones caused by the all-in addition of combustion air, thus creating optimal temperature conditions for reactions such as the reduction roasting of weakly magnetic iron ore and pyrolusite.

[0057] Furthermore, in this embodiment, the burner is installed on a φ4m×50m rotary kiln, and the physical and chemical parameters of the coal are shown in Table 2.

[0058] Table 2 Analysis results of physical and chemical parameters of coal

[0059] Ash content (%) Volatile matter (%) Ignition temperature ℃ Fixed carbon (%) Calorific value (kcal / kg) Sulfur content (%) 8 34.66 369 54.58 7687.4 / 6843 0.37

[0060] The coal is finely ground by Raymond mill + hot air drying + wind conveying and then classified into +0.10mm coarse coal powder and -0.10mm fine coal powder and stored in appropriate silos. The temperature field distribution in the rotary kiln after the coal injection combustion is carried out by the fuel graded uniform temperature field burner of the present invention is compared with that after the conventional burner combustion. Figure 5 As shown in the figure, the measured temperature results of thermocouples at different positions in the rotary kiln show that, compared with the temperature field distribution after combustion of a conventional burner, the peak temperature of the flame in the rotary kiln after combustion of the burner of the present invention is reduced by about 10%, and the high temperature maintenance area is extended by about 20%. The temperature field formed by the burner of the magnetic roasting rotary kiln described in the present invention is more adapted to the uniform temperature field expected for magnetic roasting of iron ore.

[0061] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A burner for a magnetized roasting rotary kiln, characterized in that: The invention comprises a coarse-grained coal powder supply channel (2), a coarse-grained coal powder conveying air channel (1), a primary combustion-supporting air supply channel (3), a fine-grained coal powder supply channel (4) and a fine-grained coal powder conveying air channel (5), all of which are formed by circular pipe fittings. The primary combustion-supporting air supply channel (3) is intermittently sleeved on the outside of the coarse-grained coal powder supply channel (2), the fine-grained coal powder supply channel (4) is intermittently sleeved on the outside of the primary combustion-supporting air supply channel (3), the output end of the coarse-grained coal powder conveying air channel (1) is inserted into the input end of the coarse-grained coal powder supply channel (2) and is arranged in the conveying direction of the coarse-grained coal powder. The output end of the fine coal powder conveying air channel (5) is plugged into the input end of the fine coal powder supply channel (4) and is arranged toward the conveying direction of the fine coal powder; the fine coal powder supply channel (4) comprises a fine coal powder supply sleeve (41), a fine coal powder supply gradually expanding pipe (42) and a fine coal powder supply straight pipe (43); the fine coal powder supply gradually expanding pipe (42) is coaxially connected to the fine coal powder supply sleeve (41); one end of the fine coal powder supply straight pipe (43) is connected to the side wall of the fine coal powder supply gradually expanding pipe (42), and the other end is provided with a fine coal powder supply straight pipe flange (44).

2. The burner for a magnetized roasting rotary kiln according to claim 1, characterized in that: It also includes a secondary combustion-supporting air supply channel (6), wherein the secondary combustion-supporting air supply channel (6) is sleeved on the outside of the fine coal powder supply channel (4).

3. The burner for a magnetized roasting rotary kiln according to claim 2, characterized in that: The fine-particle coal powder conveying air channel (5) comprises a fine-particle coal powder conveying air straight pipe (51) and a fine-particle coal powder conveying air sleeve (52) arranged to intersect each other. The fine-particle coal powder conveying air sleeve (52) is sleeved on the outside of the primary combustion air supply channel (3). A fine-particle coal powder conveying air straight pipe flange (53) is installed at the input end of the fine-particle coal powder conveying air straight pipe (51).

4. The burner for a magnetized roasting rotary kiln according to claim 3, characterized in that: The secondary combustion air supply channel (6) is gap-sheathed on the outside of the fine coal powder supply sleeve (41).

5. The burner for a magnetized roasting rotary kiln according to claim 4, characterized in that: The output end of the fine coal powder supply straight pipe (43) is arranged toward the output end of the fine coal powder conveying air sleeve (52).

6. The burner for a magnetized roasting rotary kiln according to claim 4, characterized in that: The secondary combustion air supply channel (6) includes a secondary combustion air supply straight pipe (61) and a secondary combustion air supply sleeve (62) arranged to intersect each other. The secondary combustion air supply sleeve (62) is sleeved on the outside of the fine coal powder supply sleeve (41) with a gap, and a secondary combustion air supply straight pipe flange (63) is installed at the input end of the secondary combustion air supply straight pipe (61).

7. The burner for a magnetized roasting rotary kiln according to claim 1, characterized in that: The primary combustion-supporting air supply channel (3) comprises a primary combustion-supporting air supply straight pipe (31) and a primary combustion-supporting air supply sleeve (32) arranged to intersect each other. The primary combustion-supporting air supply sleeve (32) is sleeved on the outside of the coarse-grained coal powder supply channel (2) with a gap, and a primary combustion-supporting air supply straight pipe flange (33) is installed at the input end of the primary combustion-supporting air supply straight pipe (31).

8. The burner for a magnetized roasting rotary kiln according to claim 7, characterized in that: The coarse-grained coal powder supply channel (2) includes a coarse-grained coal powder supply elbow (21), a coarse-grained coal powder supply straight pipe (22) connected to both ends of the coarse-grained coal powder supply elbow (21), and a coarse-grained coal powder supply center pipe (23); the primary combustion air supply sleeve (32) is sleeved on the outside of the coarse-grained coal powder supply center pipe (23); a coarse-grained coal powder supply straight pipe flange (24) is installed at the input end of the coarse-grained coal powder supply straight pipe (22); the coarse-grained coal powder conveying air channel (1) includes a coarse-grained coal powder conveying air straight pipe (11) inserted into the coarse-grained coal powder supply elbow (21); and a coarse-grained coal powder conveying air flange (12) is provided at the end of the coarse-grained coal powder conveying air straight pipe (11).

9. The burner for a magnetized roasting rotary kiln according to claim 8, characterized in that: The coarse-grained coal powder conveying air straight pipe (11) and the coarse-grained coal powder supply central pipe (23) are coaxially arranged.

10. The burner for a magnetized roasting rotary kiln according to any one of claims 2 to 9, characterized in that: The output ends of the coarse-grained coal powder supply channel (2), the primary combustion-supporting air supply channel (3), the fine-grained coal powder supply channel (4) and the secondary combustion-supporting air supply channel (6) are coaxially arranged, and the edges of the output ends of the coarse-grained coal powder supply channel (2), the primary combustion-supporting air supply channel (3), the fine-grained coal powder supply channel (4) and the secondary combustion-supporting air supply channel (6) are flush arranged.

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