A burner for atmosphere control of magnetized roasting rotary kiln

Abstract

The present invention discloses a burner for atmosphere control of a magnetization roasting rotary kiln, which includes a fuel supply channel and a primary air supply channel. The fuel supply channel is sleeved outside the primary air supply channel with a gap. One end of the fuel supply channel is provided with a fuel outlet, and the other end is provided with a fuel inlet. One end of the primary air supply channel is provided with a primary air outlet, and the other end is provided with a primary air inlet. In the burner of the present invention, the central channel is an auxiliary gas channel, and the fuel flow is distributed outside the auxiliary gas to wrap the combustion air flow. In this combustion mode, the fuel diffuses in two directions, radially inward and outward, with a double gradient. The fuel combustion reaction area is closer to the material layer, greatly reducing the O2 partial pressure in the interfacial area of the material layer, thereby controlling the atmosphere in the material reaction area, avoiding secondary oxidation of the completely reduced roasted ore, and thus improving the reduction rate of the roasting product.

Description

Technical Field

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

[0002] Rotary kiln reduction roasting is widely used in industrial production of magnetization roasting of weakly magnetic iron ore and reduction roasting of pyrolusite. Generally speaking, the reaction temperature of rotary kiln magnetization roasting of weakly magnetic iron ore is 650℃~800℃, and the reaction temperature of rotary kiln reduction roasting of pyrolusite is 700℃~850℃. The temperature required for the reaction is not very high, but the high temperature needs to be maintained for a long time, and the atmosphere field in the kiln needs to be controlled by zones. The principle of atmosphere field zoning control is: a reducing atmosphere needs to be maintained in and near the reaction area of ​​the material layer; and in order to make full use of the fuel and improve the combustion rate of the fuel, the combustion zone (i.e. the upper cavity of the material layer) requires an oxidizing atmosphere. Traditional multi-channel burners provide fuel to the central channel and combustion-supporting gas to the outer channel. In this combustion method, the combustion-supporting gas flow wraps the fuel flow in the outer layer. Most of the flue gas in the area near the reaction material layer is air that has not been completely burned, which produces a strong oxidizing atmosphere field, which is not conducive to the formation of the atmosphere field required for the reduction reaction; at the same time, when using ordinary coal with poor combustion performance and reaction activity, in order to improve the coal burnout rate and reduce coal consumption, some roasting plants have to use oxygen-enriched combustion devices, resulting in a higher oxygen partial pressure in the material layer interface area, which is even more unfavorable for the zoning control of the atmosphere field, resulting in the inability to maintain the atmosphere field required for the gas-solid reaction in the rotary kiln, which is easy to cause the reduced roasted ore to be secondary oxidized, thereby reducing the reduction rate of the roasted product.

[0003] Therefore, in view of the above-mentioned defects of traditional burners, an atmosphere control burner is developed, which has important practical significance for high-temperature roasting processes that require control of the reaction atmosphere. Summary of the invention

[0004] The object of the present invention is to provide a burner for controlling the atmosphere of a magnetized roasting rotary kiln, thereby solving the above-mentioned problems.

[0005] To achieve the above-mentioned purpose, the present invention discloses a burner for controlling the atmosphere of a magnetized roasting rotary kiln, comprising a fuel supply channel and a primary air supply channel, wherein the fuel supply channel is gap-sleeved on the outside of the primary air supply channel, a fuel output port is provided at one end of the fuel supply channel, and a fuel supply port is provided at the other end, and a primary air output port is provided at one end of the primary air supply channel, and a primary air supply port is provided at the other end.

[0006] Furthermore, a fuel diffuser tube and a fuel straight tube are installed at the other end of the fuel supply channel. The fuel diffuser tube is sleeved on the outside of the primary air supply channel and is connected to the other end of the fuel supply channel. One end of the fuel straight tube is installed on the side wall of the fuel diffuser tube, and the other end is provided with the fuel supply inlet.

[0007] Furthermore, a fuel straight pipe flange for connecting to external equipment is provided at the other end of the fuel straight pipe.

[0008] Furthermore, the edges of the fuel outlet and the primary air outlet are arranged flush with each other.

[0009] Furthermore, the fuel supply channel is configured to allow gaseous fuel to flow into it.

[0010] Furthermore, it also includes a secondary air supply channel, which is sleeved on the outside of the other end of the primary air supply channel. One end of the secondary air supply channel is provided with a secondary air outlet, and the other end is provided with a secondary air supply inlet. The secondary air outlet is provided close to the fuel supply inlet.

[0011] Furthermore, the secondary air supply channel is configured to be axially adjustable relative to the primary air supply channel.

[0012] Furthermore, a secondary air gradual expansion tube and a secondary air straight tube are installed at the other end of the secondary air supply channel. The secondary air gradual expansion tube is sleeved on the outside of the secondary air supply channel and is connected to the other end of the secondary air supply channel. One end of the secondary air straight tube is installed on the side wall of the secondary air gradual expansion tube, and the other end is provided with the secondary air supply inlet.

[0013] Furthermore, the other end of the secondary air straight pipe is provided with a secondary air straight pipe flange for connecting to external equipment.

[0014] Furthermore, the fuel supply channel and the primary air supply channel, as well as the secondary air supply channel and the primary air supply channel are separated by high temperature resistant steel, and the fuel supply channel is configured to allow gas fuel or powdered solid fuel to pass through.

[0015] Compared with the prior art, the advantages of the present invention are:

[0016] 1. The central channel of the burner of the present invention is a combustion-supporting gas channel, and the fuel flow is distributed outside the combustion-supporting gas to wrap the combustion-supporting air flow. In this combustion mode, the fuel diffuses in both radial inward and outward directions with double gradients, and the fuel combustion reaction occurs in an area closer to the material layer, which greatly reduces the O 2 The partial pressure is increased to control the atmosphere in the material reaction area, thereby avoiding secondary oxidation of the roasted ore that has been completely reduced, thereby increasing the reduction rate of the roasted product.

[0017] 2. The burner of the present invention does not have a swirl channel and premixing zone for fuel and air. The fuel is mainly mixed with the air by being drawn in during the primary wind jet process. The pressure loss during the flue gas flow process is relatively small and the injection distance is relatively longer. Therefore, the combustion speed is slower than that of the traditional burner and the combustion intensity is slightly weaker. The peak flame temperature can be reduced and the flame length in the high-temperature zone can be extended. While avoiding excessive local temperature in the reactor, the high-temperature maintenance time of the material is extended to ensure that the reduction reaction is complete.

[0018] 3. Compared with traditional burners, the invented burner has a longer fuel injection distance and a more uniform fuel distribution in the reactor, thereby reducing the peak flame temperature and avoiding the problem of excessive local temperature causing a large amount of thermal NOx gas to be generated, making the combustion and reduction process greener and more environmentally friendly.

[0019] 4. The burner of the present invention can be used for the combustion of solid fuels such as coal powder, biomass, or (and) gaseous fuels such as coal gas, natural gas, blast furnace gas, etc., and has stronger adaptability to fuels; at the same time, when using gaseous fuel, there is no need to set a secondary air supply channel, and the equipment structure is simpler and more reliable.

[0020] The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0022] Figure 1 It is a schematic structural diagram of a burner for controlling the atmosphere of a magnetized roasting rotary kiln disclosed in a preferred embodiment 1 of the present invention;

[0023] Figure 2 It is a schematic diagram of the movement streamlines of materials and combustion-supporting gas in a burner for controlling the atmosphere of a magnetized roasting rotary kiln disclosed in a preferred embodiment of the present invention;

[0024] Figure 3 It is a schematic diagram of the structure of a burner for controlling the atmosphere of a magnetized roasting rotary kiln disclosed in the second preferred embodiment of the present invention;

[0025] Figure 4 It is a schematic diagram of CO concentration distribution at 10 m from the kiln head in the rotary kiln when the burner in the second preferred embodiment of the present invention is used.

[0026] Legend:

[0027] 1. Fuel supply inlet; 2. Fuel supply channel; 21. Fuel outlet; 23. Fuel expansion tube; 24. Fuel straight tube; 25. Fuel straight tube flange; 3. Primary air supply channel; 31. Primary air outlet; 32. Primary air supply inlet; 33. Primary air flange; 4. Secondary air supply channel; 41. Secondary air outlet; 42. Secondary air supply inlet; 43. Secondary air expansion tube; 44. Secondary air straight tube; 45. Secondary air straight tube flange. DETAILED DESCRIPTION

[0028] The embodiments of the present invention are described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0029] Embodiment 1:

[0030] like Figure 1-2 As shown, the embodiment of the present invention discloses a burner for atmosphere control of a magnetized roasting rotary kiln, which is a natural gas burner, including a fuel supply channel 2 and a primary air supply channel 3. The fuel supply channel 2 is fed with gaseous fuels such as coal gas, natural gas, and blast furnace gas. The primary air supply channel 3 is circular, and the natural gas fuel supply channel 2 is annular, and the two are connected by welding. The fuel supply channel 2 is sleeved on the outside of the primary air supply channel 3 with a gap, coaxially arranged, and separated by high-temperature resistant steel. A fuel output port 21 is provided at one end of the fuel supply channel 2, and a fuel supply inlet 1 is provided at the other end. A primary air output port 31 is provided at one end of the primary air supply channel 3, and a primary air supply inlet 32 ​​is provided at the other end. The primary air supply inlet 32 ​​is equipped with a primary air flange 33, so as to facilitate the connection of an external air supply duct. The edges of the fuel output port 21 and the primary air output port 31 are arranged flush, which is convenient for positioning and installation during assembly.

[0031] In this embodiment, a fuel diffuser 23 and a fuel straight pipe 24 are installed at the other end of the fuel supply channel 2. The axes of the fuel diffuser 23 and the fuel straight pipe 24 are perpendicular and connected by welding. The fuel diffuser 23 is sleeved outside the primary air supply channel 3. The fuel diffuser 23 is welded to the other end of the fuel supply channel 2. One end of the fuel straight pipe 24 is installed on the side wall of the fuel diffuser 23, and the other end is provided with a fuel supply port 1. External fuel is injected into the fuel supply channel 2 through the edges of the fuel diffuser 23 and the fuel straight pipe 24, avoiding the problem that the fuel straight pipe 24 cannot be directly welded to the fuel supply channel 2.

[0032] In this embodiment, the other end of the fuel straight pipe 24 is provided with a fuel straight pipe flange 25 for connecting to external equipment, so as to be connected to an external natural gas storage device or natural gas pipeline through a flange and a pipeline. The air supply volume of the primary air is reasonably adjusted according to the natural gas injection volume, so as to maintain an ideal reducing atmosphere field distribution in the internal area of ​​the reactor.

[0033] Embodiment 2:

[0034] like Figure 3-4 As shown, the embodiment of the present invention discloses a burner for atmosphere control of a magnetized roasting rotary kiln, which is a pulverized coal burner. Its structural layout is basically the same as that of the first embodiment, except that it also includes a secondary air supply channel 4, which is also circular or annular. The secondary air supply channel 4 is sleeved on the outside of the other end of the primary air supply channel 3 and separated by high-temperature resistant steel. A secondary air outlet 41 is provided at one end of the secondary air supply channel 4, and a secondary air supply inlet 42 is provided at the other end. The secondary air outlet 41 is provided close to the fuel supply inlet 1, so that the pulverized coal in the fuel supply channel 2 is fed into the reaction furnace at a high speed through the ejection effect of the secondary air supply channel 4.

[0035] In this embodiment, the secondary air supply channel 4 is configured to be axially adjustable relative to the primary air supply channel 3, that is, the insertion depth of the secondary air outlet 41 is adjustable, thereby flexibly adjusting the injection effect of the burner fuel.

[0036] In this embodiment, a secondary air diffuser 43 and a secondary air straight pipe 44 are installed at the other end of the secondary air supply channel 4. The axes of the secondary air diffuser 43 and the secondary air straight pipe 44 are perpendicular to each other. The secondary air diffuser 43 is sleeved on the outside of the primary air supply channel 3. The secondary air diffuser 43 is welded to the other end of the secondary air supply channel 4. One end of the secondary air straight pipe 44 is installed on the side wall of the secondary air diffuser 43, and the other end is provided with a secondary air supply inlet 42, so that the secondary air and primary air supply volumes can be reasonably adjusted according to the coal powder injection amount, so as to maintain the ideal reducing atmosphere field distribution in the internal area of ​​the reactor.

[0037] In this embodiment, the other end of the secondary air straight pipe 44 is provided with a secondary air straight pipe flange 45 for connecting to external equipment, thereby facilitating connection with an external gas supply device through a pipeline.

[0038] Furthermore, the coal-fired burner of the present invention is used in this embodiment. The burner is installed on a rotary kiln with a specification of φ4m×50m. The physical and chemical parameters of the coal are shown in Table 1.

[0039] Table 1 Analysis results of physical and chemical parameters of coal

[0040] 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

[0041] After the coal is crushed, it is stored in the pulverized coal bin. After being accurately measured by the metering device, the pulverized coal is sprayed into the rotary kiln through the burner of the present invention for combustion. The schematic diagram of the flow trajectory of the pulverized coal and the combustion-supporting gas in the rotary kiln is shown in FIG. Figure 2 The CO concentration distribution diagram in the rotary kiln at 10m away from the kiln head is as follows: Figure 4 shown.

[0042] From the attached Figure 4 The results show that after the burner of the present invention burns, the radial CO concentration 10m away from the kiln head is approximately in an "M" shape distribution, with low concentration in the central area, and the CO concentration first increases and then slowly decreases toward the kiln wall. Compared with the radial CO concentration after combustion of 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 after combustion, which is consistent with the reducing atmosphere field requirement for material reaction.

[0043] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A burner for atmosphere control of a magnetized roasting rotary kiln, It is characterized in that The invention comprises a fuel supply channel (2) and a primary air supply channel (3), wherein the fuel supply channel (2) is sleeved on the outside of the primary air supply channel (3), one end of the fuel supply channel (2) is provided with a fuel output port (21), and the other end is provided with a fuel supply port (1), one end of the primary air supply channel (3) is provided with a primary air output port (31), and the other end is provided with a primary air supply port (32); a fuel gradual expansion tube (23) and a fuel straight tube (24) are installed on the other end of the fuel supply channel (2), the fuel gradual expansion tube (23) is sleeved on the outside of the primary air supply channel (3), the fuel gradual expansion tube (23) is connected to the other end of the fuel supply channel (2), one end of the fuel straight tube (24) is installed on the side wall of the fuel gradual expansion tube (23), and the other end is provided with the fuel supply port (1); the fuel output port ( 21) and the edge of the primary air outlet (31) are arranged flush; it also includes a secondary air supply channel (4), the secondary air supply channel (4) is sleeved on the outside of the other end of the primary air supply channel (3), one end of the secondary air supply channel (4) is provided with a secondary air outlet (41), and the other end is provided with a secondary air supply inlet (42), the secondary air outlet (41) is arranged close to the fuel supply inlet (1); the other end of the secondary air supply channel (4) is installed with a secondary air gradual expansion tube (43) and a secondary air straight tube (44), the secondary air gradual expansion tube (43) is sleeved outside the primary air supply channel (3), the secondary air gradual expansion tube (43) is connected to the other end of the secondary air supply channel (4), one end of the secondary air straight tube (44) is installed on the side wall of the secondary air gradual expansion tube (43), and the other end is provided with the secondary air supply inlet (42).

2. The burner for controlling the atmosphere of the magnetized roasting rotary kiln according to claim 1, It is characterized in that The other end of the fuel straight pipe (24) is provided with a fuel straight pipe flange (25) for connecting to external equipment.

3. The burner for controlling the atmosphere of the magnetized roasting rotary kiln according to claim 1, It is characterized in that The fuel supply channel (2) is configured to allow gaseous fuel to flow into it.

4. The burner for controlling the atmosphere of the magnetized roasting rotary kiln according to claim 1, It is characterized in that The secondary air supply channel (4) is arranged to be axially adjustable relative to the primary air supply channel (3).

5. The burner for controlling the atmosphere of the magnetized roasting rotary kiln according to claim 1, It is characterized in that The other end of the secondary air straight pipe (44) is provided with a secondary air straight pipe flange (45) for connecting to external equipment.

6. The burner for controlling the atmosphere of a magnetized roasting rotary kiln according to any one of claims 1 to 3, It is characterized in that The fuel supply channel (2) and the primary air supply channel (3), and the secondary air supply channel (4) and the primary air supply channel (3) are separated by high temperature resistant steel.

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