Cement kiln burner device

Abstract

To provide a cement kiln burner device capable of suppressing the occurrence of landing combustion of combustible waste while promoting the combustion of combustible waste.SOLUTION: The cement kiln burner device comprising a plurality of flow passages partitioned by a plurality of concentric cylindrical members, comprises a solid powder fuel flow passage allowing solid powder fuel to flow therethrough, a combustible waste fuel flow passage allowing the combustible waste fuel to flow therethrough, and a first air flow passage positioned in the outermost shell. The first air flow passage is configured in such a way that a plurality of first openings and a plurality of second openings each having an opening area relatively larger than that of the first openings are alternately arranged in a state of being separated from each other in the circumferential direction, and the opening area of the second opening is at least one time larger than the opening area of the first opening and at most four times larger than the opening area of the first opening.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a burner device for a cement kiln.

Background Art

[0002] Combustible wastes such as waste plastics, wood chips, and automobile shredder dust (ASR) have a calorific value that can be used as fuel for firing. Therefore, in a rotary kiln (hereinafter referred to as "cement kiln") used for firing cement clinker, the effective use of combustible waste is being promoted as an auxiliary fuel or alternative fuel to pulverized coal.

[0003] Conventionally, when introducing combustible waste into a cement kiln, utilization in the kiln tail and the pre-calciner has been promoted for reasons such as having a small impact on the quality of cement clinker and the simplicity of pretreatment such as crushing. However, when introducing waste from the kiln tail and the pre-calciner, the post-combustion of the waste causes the temperature of the gas in the subsequent stage to rise. Therefore, from the perspective of protecting the equipment arranged in the subsequent stage, water spraying treatment is carried out to lower the temperature to an appropriate level. As a result, since the heat quantity per unit decreases, when further accepting combustible waste into the cement kiln, treatment in front of the kiln is required.

[0004] The applicant of the present application has developed a burner in which a flow path for combustible waste such as waste plastic is provided inside the flow path for the main fuel in a burner for blowing pulverized coal into a cement kiln (see Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] When combustible waste is blown in from a burner installed on the front side of the kiln, the combustible waste may land on the cement clinker in the kiln and continue to burn as it is (hereinafter referred to as "landing combustion"). When landing combustion occurs, the clinker around where the combustible waste has landed is reduced-fired, resulting in whitening of the clinker and abnormalities in the clinkering reaction.

[0007] As a method for avoiding such landing combustion of combustible waste, for example, there are a method of ensuring a long floating time until landing and a method of increasing the combustion rate of combustible waste. The former has no problem when using a small amount of combustible waste while using pulverized coal as the main fuel, but when using a large amount of combustible waste, the flame shape changes significantly compared to the case of using pulverized coal as the main fuel due to poor combustion of the combustible waste, resulting in abnormal color tone of the clinker and abnormal clinkering. On the other hand, in the latter case, even when the input amount of combustible waste is large, poor combustion is less likely to occur, and the risk of deterioration of clinker quality is small.

[0008] In view of the above problems, the present invention aims to provide a burner device for a cement kiln that enables suppression of the occurrence of landing combustion of combustible waste while promoting the combustion of combustible waste when the combustible waste is introduced into the cement kiln together with a solid powder fuel such as pulverized coal.

Means for Solving the Problems

[0009] The burner device for a cement kiln according to the present invention is a burner device for a cement kiln having a plurality of flow paths partitioned by a plurality of concentric cylindrical members, a flow path for solid powder fuel through which the solid powder fuel flows, a flow path for combustible waste fuel through which the combustible waste fuel flows, and a first air flow path located in the outermost shell, outside the flow path for solid powder fuel and the flow path for combustible waste fuel, the first air flow path being configured such that a first opening and a second opening having a relatively larger opening area than the first opening are alternately arranged in a circumferentially spaced state, It is characterized in that the opening area of the second opening is larger than 1 time and equal to or less than 4 times the opening area of the first opening.

[0010] As a result of the intensive research by the present inventors, it has been confirmed that by adopting the above configuration, it is possible to suppress the ground combustion of the combustible waste while promoting the combustion of the combustible waste. Details will be described later in the section "Mode for Carrying Out the Invention".

[0011] The "combustible waste" in this specification refers to general waste and industrial waste mainly composed of organic substances such as waste plastics, wood chips, ASR, waste tires, carbon fibers, carbon fiber reinforced plastics (CFRP), meat and bone meal, or biomass, which are assumed to be used as auxiliary fuels or alternative fuels together with solid powder fuels such as pulverized coal. Note that "biomass" is an organic resource derived from organisms that can be used as a fuel excluding fossil fuels, and examples include pulverized waste tatami mats, pulverized construction waste wood, wood powder, and sawdust.

[0012] Both the first opening and the second opening have a circular shape with their centers substantially located on the same virtual circle. The opening ratio, which is the ratio of the total length passing through the first opening and the second opening to the circumference length of the virtual circle, may be 10% to 40%.

[0013] Further, in the above configuration, the first opening and the second opening may be arranged substantially equidistantly on the same virtual circle. Here, the term "substantially equidistant" means that the error range between the maximum value and the minimum value of the separation distance between adjacent openings is 10% or less.

[0014] The flow path for the combustible waste fuel may be located in the innermost shell.

[0015] The burner device for the cement kiln An annular second air flow path, which is located outside the flow path for the combustible waste fuel and inside the flow path for the solid powder fuel; It may further include an annular third air flow path, which is located outside the flow path for the solid powder fuel and inside the first air flow path.

Advantages of the Invention

[0016] According to the burner device for a cement kiln of the present invention, while promoting the combustion of the combustible waste, it is possible to suppress the ground combustion of the combustible waste. Thereby, when manufacturing cement clinker, the utilization amount of the combustible waste can be increased.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0018] An embodiment of a burner device for a cement kiln according to the present invention will be described with reference to the drawings. Note that the following drawings are schematically shown, and the dimensional ratios on the drawings do not match the actual dimensional ratios. Also, the dimensional ratios do not necessarily match between the drawings.

[0019] FIG. 1 is a cross-sectional view schematically showing an example of the installation mode of a burner device for a cement kiln. In the example shown in FIG. 1, a burner device 1 for a cement kiln (hereinafter simply referred to as "burner device 1") is installed on the front side of the kiln of a cement kiln 2 for firing cement clinker 5.

[0020] The cement kiln 2 is a device for firing a clinker raw material to produce cement clinker 5. Typically, the clinker raw material calcined through a preheater (not shown) installed on the upstream side flows into the kiln end of the cement kiln 2. The cement kiln 2 has a horizontal cylindrical shape that slopes slightly downward toward the downstream side (the kiln hood 4 side), and fires the clinker raw material (or the cement clinker 5 whose firing is partially completed) while rotating.

[0021] The upstream side of the kiln hood 4 is connected to the downstream end of the cement kiln 2 and surrounds the downstream end of the cement kiln 2. The lower part of the kiln hood 4 is connected to a clinker cooler 3. In the example of FIG. 1, the burner device 1 is attached to the downstream side wall surface 4a of the kiln hood 4. However, this installation position is merely an example, and the installation position of the burner device 1 is not limited as long as it is installed on the front side of the kiln of the cement kiln 2.

[0022] The burner device 1 feeds solid powder fuel C1 and combustible waste fuel R1 into the cement kiln 2. The cement kiln 2 fires the clinker raw material flowing in from the upstream side while using the fuel (C1, R1) fed from the burner device 1. The fired cement clinker 5 falls toward the clinker cooler 3 disposed below the kiln hood 4 and is cooled in the clinker cooler 3.

[0023] The fired cement clinker 5 is at 1,000°C or higher, typically about 1,200°C to 1,500°C. This cement clinker 5 is cooled by the ambient air AA1 at normal temperature (about 20°C to 30°C) fed from a cooling fan (not shown) connected to the clinker cooler 3. The cooled cement clinker 5 is discharged from the outlet-side end of the clinker cooler 3 and stored in a clinker silo (not shown).

[0024] The ambient air AA1 flowing into the clinker cooler 3 is heat-exchanged with the high-temperature cement clinker 5 and then supplied into the cement kiln 2 as secondary air AA2. This secondary air AA2 is used as combustion air in the burner device 1.

[0025] Hereinafter, the vertical direction is defined as the Z direction and the axial direction of the cement kiln 2 is defined as the X direction for explanation. FIG. 2 is a schematic plan view when the front end surface of the burner device 1 is viewed from the +X side.

[0026] As shown in FIG. 2, the burner device 1 includes a plurality of flow paths partitioned by a plurality of concentric cylindrical members. The burner device 1 shown in FIG. 2 includes a plurality of flow paths (7, 20, 8, 30, 10) arranged at different positions in the radial direction. More specifically, it is as follows.

[0027] The burner device 1 includes a combustible waste fuel flow path 7 through which an air flow containing the combustible waste fuel R1 flows.

[0028] The burner device 1 includes a solid powder fuel flow path 8 through which an air flow containing a solid powder fuel C1 such as pulverized coal flows. In the example of FIG. 2, the solid powder fuel flow path 8 is located outside the combustible waste fuel flow path 7.

[0029] The burner device 1 includes a plurality of air flow paths (10, 20, 30) at different positions in the radial direction.

[0030] The air flow path 10 located in the outermost shell (hereinafter referred to as the "first air flow path 10") is configured by arranging a plurality of openings at intervals in the circumferential direction. More specifically, the first air flow path 10 includes a first opening 11 and a second opening 12 having a relatively larger opening area than the first opening 11. The first opening 11 and the second opening 12 are alternately arranged in a state of being separated from each other in the circumferential direction. The ratio (S2 / S1) of the opening area S2 of the second opening 12 to the opening area S1 of the first opening 11 is greater than 1 times and less than or equal to 4 times, and more preferably, greater than or equal to 2 times and less than or equal to 3.5 times.

[0031] The first opening 11 and the second opening 12 are arranged to be separated from each other on the virtual circle 10c. As a more detailed example, both the first opening 11 and the second opening 12 are circular, and the centers of the circles are substantially located on the virtual circle 10c. Note that "substantially located on the virtual circle 10c" means that in addition to the case where the center of the first opening 11 and the center of the second opening 12 completely coincide on the virtual circle 10c, the deviation of the center of one or more of the first opening 11 and the second opening 12 constituting the first air flow path 10 from the virtual circle 10c is 10% or less of the diameter of the opening.

[0032] The total number of each opening (11, 12) constituting the first air flow path 10 is not limited. However, if the number of openings is made too small while ensuring the total opening area, it is necessary to increase the size of each opening (11, 12). In this case, in order to secure a region for forming each opening (11, 12), the diameter of the burner device 1 may increase, and the manufacturing cost may increase. From this perspective, the total number of each opening (11, 12) is preferably 8 to 24, and more preferably 12 to 20. In addition, from the perspective of making the number of the first opening 11 and the second opening 12 the same, the total number of each opening (11, 12) is more preferably an even number, but the total number of each opening (11, 12) may be an odd number.

[0033] The opening ratio of the first air flow path 10 is preferably 10% to 40%, more preferably 10% to 30%. In this specification, the opening ratio of the first air flow path 10 is defined as the ratio of the total length that the virtual circle 10c passes through each opening (11, 12) to the circumferential length of the virtual circle 10c in FIG. 2.

[0034] A decrease in the opening ratio of the first air flow path 10 leads to a reduction in the region where the air flow of the outermost shell is formed. The air flow of the outermost shell serves as a barrier to suppress the inflow of the high-temperature secondary air AA2 existing outside into the inside. That is, when the opening ratio of the first air flow path 10 decreases and the region where the air flow of the outermost shell is formed decreases, it becomes easier for the high-temperature secondary air AA2 to flow into the inside from the outside. As a result, it can be said that the gas temperature near the tip of the burner device 1 rises, contributing to the early combustion of the combustible waste fuel R1.

[0035] Conversely, when the opening ratio of the first air flow path 10 increases, the flow rate of the air flow from the first air flow path 10 forming the outermost flow relatively increases, so this air flow becomes a barrier and it becomes difficult for the high-temperature secondary air AA2 to enter in the direction of the center of the burner device 1. As a result, the gas temperature near the tip of the burner device 1 decreases. From the viewpoint of early ignition of the combustible waste fuel R1 introduced from the burner device 1 to realize a stable flame, it is preferable to set the opening ratio of the first air flow path 10 to 40% or less.

[0036] From the perspective of igniting the combustible waste fuel R1 early and suppressing the ground combustion, it seems advisable to reduce the opening ratio of the first air flow path 10 as much as possible in order to increase the gas temperature near the tip of the burner device 1. However, according to the intensive research of the present inventor, it has been newly confirmed that when the opening ratio of the first air flow path 10 is reduced too much, conversely, the landing rate of the combustible waste fuel R1 tends to increase. The present inventor infers the reason as follows. When the opening ratio of the first air flow path 10 is set too low, the flow rate of the air flow from the first air flow path 10 forming the outermost flow becomes relatively low, and the combustible waste fuel R1 and the solid powder fuel C1 introduced from the inside rather than the first air flow path 10 tend to flow from the center of the burner device 1 toward the outside. As a result, there is a possibility that the combustible waste fuel R1 and the like land on the upper surface of the cement clinker 5 before burning out.

[0037] From the above perspective, it is preferable to set the opening ratio of the first air flow path 10 to 10% - 30%, and more preferably to 15% - 25%.

[0038] In addition, when the opening area S1 of the first opening 11 is made too small compared to the opening area S2 of the second opening 12, the influence of the air flow from the second opening 12 becomes dominant compared to the air flow from the first opening 11. In this case, it is considered that the same phenomenon as when the opening ratio of the first air flow path 10 is reduced occurs. As will be described later with reference to the examples, from the perspective of reducing the landing rate of the combustible waste fuel R1, the ratio (S2 / S1) of the opening area S2 of the second opening 12 to the opening area S1 of the first opening 11 is preferably greater than 1 times and less than or equal to 4 times, and more preferably greater than or equal to 2 times and less than or equal to 3.5 times.

[0039] The burner device 1 shown in FIG. 2 includes an annular second air flow path 20 between the flow path 7 for combustible waste fuel and the flow path 8 for solid powder fuel in the radial direction. Further, the burner device 1 shown in FIG. 2 includes an annular third air flow path 30 between the flow path 8 for solid powder fuel and the first air flow path 10 in the radial direction.

[0040] Preferably, swirling air flows are blown into the cement kiln 2 from the second air flow path 20 and the third air flow path 30, respectively. Also preferably, a straight air flow is blown into the cement kiln 2 from each opening (11, 12) constituting the first air flow path 10. However, in the present invention, the air flows blown from the first air flow path 10, the second air flow path 20, and the third air flow path 30 may be straight flows or swirling flows.

[0041] The burner device 1 may separately provide a flow path for blowing a liquid fuel (such as oil) into the cement kiln 2, in addition to the flow path 7 for the combustible waste fuel, inside the second air flow path 20.

[0042] The burner device 1 may be configured to include only one of the second air flow path 20 and the third air flow path 30. The burner device 1 may include an additional air flow path between the combustible waste fuel flow path 7 and the solid powder fuel flow path 8 in the radial direction. The burner device 1 may include an additional air flow path between the solid powder fuel flow path 8 and the first air flow path 10 in the radial direction.

Example

[0043] A simulation was performed on the influence of the opening ratio of the first air flow path 10 and the area ratio between the first opening 11 and the second opening 12 on the gas temperature and the combustible waste fuel R1. The simulation conditions are described below.

[0044] FIG. 3 is a schematic drawing of a cement kiln model 40 used in the simulation. The cement kiln model 40 was set in a cylindrical shape with a diameter of 4.7 m and a length of 30 m. A burner device 1 was installed at a first end 41 that simulated the front of the kiln, and a state in which solid powder fuel C1, combustible waste fuel R1, and air flowed into the cement kiln model 40 from this burner device 1 was simulated. Further, high-temperature secondary air 52 flowed into the cement kiln model 40 from the first end 41, and a state in which combustion gas was exhausted from a second end 42 on the opposite side of the first end 41 was simulated.

[0045] The flow rates and temperatures of the air flow and fuel flow flowing in from the burner device 1, and the flow rate and temperature of the secondary air 52 introduced from the first end portion 41 were respectively set to the conditions in Table 1 below.

[0046]

Table 1

[0047] The combustible waste fuel R1 was in the form of a sheet of waste plastic with a diameter of 30 mm and a thickness of 1 mm, and the input amount was set to 1 t / h. The solid powder fuel C1 was pulverized coal, and the input amount was set to 11 t / h. During the simulation, the software FLUENT ver.2022R2 manufactured by ANSYS was used.

[0048] <Verification 1> First, the influence of the value of the opening ratio of the first air flow path 10 on the gas temperature and the landing rate of the combustible waste fuel R1 was verified. Here, with the areas of the first opening 11 and the second opening 12 being the same and fixed, a simulation was performed with the opening ratio of the first air flow path 10 changed from 10% to 40%, and the gas temperature and the landing rate of the combustible waste fuel R1 were calculated.

[0049] As the gas temperature, the value of the "0.5 m gas temperature" calculated by the following method was adopted. In the cement kiln model 40, a circular surface area with a diameter of 600 mm centered on the axis of the burner device 1 was set at a location 0.5 m away from the tip of the burner device 1 installed at the first end portion 41 in the axial direction of the cement kiln model 40. Then, the average gas temperature within this surface area was taken as the value of the 0.5 m gas temperature. The higher the value of the 0.5 m gas temperature, the higher the mixing property between the combustible waste fuel R1 and the high-temperature secondary air 52 is considered to be.

[0050] As the landing rate of the combustible waste fuel R1, the value obtained by dividing the amount of the combustible waste fuel R1 that collided with the inner wall of the cement kiln model 40 without complete combustion in the internal space of the cement kiln model 40 by the input amount (here, 1 t / h) was adopted. The lower the value of the landing rate of the combustible waste fuel R1, the lower the ratio of the combustible waste fuel R1 landing on the upper surface of the cement clinker 5 before the combustible waste fuel R1 burns out, and it is considered that the influence on the cement clinker 5 is low.

[0051] The simulation results are shown in Table 2 and Figure 4. In the following description, the "landing rate of the combustible waste fuel R1" may be simply referred to as the "landing rate of waste plastic".

[0052]

Table 2

[0053] According to Table 2 and Figure 4, as the opening ratio of the first air flow path 10 decreased, the 0.5 m gas temperature increased. As shown in Figure 2, the first air flow path 10 forms the outermost shell flow path. The decrease in the opening ratio of the first air flow path 10 means that the blocked portion of the outermost shell flow path increases. That is, in the air flow forming the outermost flow that flows into the cement kiln model 40 from the first air flow path 10, the flow rate of the air flow at the location corresponding to the blocked portion decreases, so that the high-temperature secondary air 52 existing outside it easily flows inward (toward the axis of the burner device 1), and it is speculated that the 0.5 m gas temperature increased.

[0054] On the other hand, according to Table 2 and Figure 4, the landing rate of waste plastic (the landing rate of the combustible waste fuel R1) showed a minimum value when the opening ratio of the first air flow path 10 was 20%. More specifically, when the opening ratio of the first air flow path 10 was lower than 20%, the landing rate of waste plastic tended to increase as the opening ratio decreased. Also, when the opening ratio of the first air flow path 10 was higher than 20%, the landing rate of waste plastic tended to increase as the opening ratio increased.

[0055] When the opening ratio of the first air flow path 10 is lower than 20%, as the opening ratio decreases, the blocked portion of the outermost shell flow path increases. As a result, it is presumed that the combustible waste fuel R1 input from the burner device 1 scattered outside beyond the barrier of the air flow forming the outermost flow and fell early.

[0056] On the other hand, when the opening ratio of the first air flow path 10 is higher than 20%, as the opening ratio increases, the outermost flow blown in from the first air flow path 10 becomes a high barrier, making it difficult for the high-temperature secondary air 52 to flow inward (toward the axis of the burner device 1). As a result, the temperature rise rate of the combustible waste fuel R1 input from the burner device 1 slows down, and it is presumed that it takes time to burn out completely. This is also consistent with the fact that the 0.5 m gas temperature decreases as the opening ratio increases.

[0057] At the time of filing this application, in an actual cement manufacturing facility, when manufacturing cement using a fuel containing the combustible waste fuel R1, if the landing rate of the combustible waste fuel R1 is 22.8% or less, the impact on the quality of the cement clinker 5 is considered to be within an acceptable range. Considering this point, it is suggested that if the opening ratio of the first air flow path 10 is within the range of 10% to 40%, the impact on the quality of the cement clinker 5 is small. According to the results of FIG. 4, it can be said that the opening ratio of the first air flow path 10 is more preferably set within the range of 10% to 30%, and particularly preferably set within the range of 15% to 25%.

[0058] <Verification 2> Next, with the opening ratio of the first air flow path 10 fixed, the influence of the area ratio between the first opening 11 and the second opening 12 forming the first air flow path 10 on the gas temperature and the landing rate of the combustible waste fuel R1 was verified.

[0059] Specifically, the opening ratio of the first air flow path 10 was fixed at 20% (level #2) where the value of the waste plastic landing rate was the minimum in Verification 1, and the ratio of the area of the second opening 12 to the area of the first opening 11 was varied within the range of 1 to 10 times for simulation. The results of this simulation are shown in Table 3 and FIG. 5.

[0060]

Table 3

[0061] According to Table 3 and FIG. 5, when the ratio of the area of the second opening 12 to the area of the first opening 11 (hereinafter, may be simply abbreviated as "area ratio") is within the range of 1 to 10 times, the 0.5 m gas temperature increases with the increase of the area ratio. The reason for this is that the air volume and air velocity are different between the air flow from the first opening 11 with a relatively small opening area and the air flow from the second opening 12 with a relatively large opening area, so the mixing of the air flow from the first air flow path 10 forming the outermost flow is promoted. As a result, it is considered that the mixing between the high-temperature secondary air 52 and the primary air is promoted in a form involved in this mixing.

[0062] On the other hand, according to Table 3 and FIG. 5, the trend of the waste plastic landing rate is different from the trend of the 0.5 m gas temperature, and the waste plastic landing rate shows the minimum value when the area ratio is 3. More specifically, when the area ratio is lower than 3, the waste plastic landing rate tends to increase with the decrease of the area ratio. Also, when the area ratio is higher than 3, the waste plastic landing rate tends to increase with the increase of the area ratio.

[0063] When the area ratio is lower than 3, it is presumed that the effect of promoting the mixing between the high-temperature secondary air 52 and the primary air, as described above, cannot be sufficiently obtained with the decrease of the area ratio. On the other hand, when the area ratio is higher than 3, with the increase of the area ratio, the air volume of the air flow from the first opening 11 with a relatively small opening area decreases, and the air velocity also slows down. For the same reason as when the opening ratio of the first air flow path 10 is low, it is presumed that the combustible waste fuel R1 scatters outside beyond the barrier of the air flow forming the outermost flow and falls early.

[0064] Incidentally, as described above, if the target upper limit value of the landing rate of the combustible waste fuel R1 is set to 22.8%, when the opening ratio of the first air flow path 10 is 20%, if the area ratio is higher than 1 times and lower than or equal to 10 times, the landing rate of the combustible waste fuel R1 can be made lower than the target upper limit value. In particular, by setting the area ratio to be higher than 1 times and lower than or equal to 4 times, it can be seen that the landing rate of the combustible waste fuel R1 can be further reduced compared to the case where the first air flow path 10 is formed by a group of openings of the same size. According to FIG. 5, a more preferable area ratio is from 2 times to 3.5 times.

[0065] Incidentally, just in case, in Verification 1, when the opening ratio of the first air flow path 10, which showed the lowest value of the landing rate of the combustible waste fuel R1, was set to 40% (level #5), the simulation was performed with the area ratio set to 4 times. The results of this simulation are shown in Table 4 and FIG. 6.

[0066]

Table 4

[0067] According to Table 4 and FIG. 6, even when the opening ratio of the first air flow path 10 is 40%, by quadrupling the ratio of the area of the second opening 12 to the area of the first opening 11 (area ratio), it can be seen that the landing rate of the combustible waste fuel R1 can be reduced compared to the case where the first air flow path 10 is formed by a group of openings of the same size. Incidentally, considering the results of FIG. 5 as well, if the ratio of the area of the second opening 12 to the area of the first opening 11 is within the range higher than 1 times and lower than or equal to 4 times, even when the opening ratio of the first air flow path 10 is 40%, it is presumed that the landing rate of the combustible waste fuel R1 can be reduced compared to the case where the first air flow path 10 is formed by a group of openings of the same size.

[0068] That is, according to the above verification, regardless of the opening ratio of the first air flow path 10, by setting the ratio of the area of the second opening 12 to the area of the first opening 11 to be higher than 1 times and lower than or equal to 4 times, it is suggested that the landing rate of the combustible waste fuel R1 can be reduced compared to the case where the first air flow path 10 is formed by a group of openings of the same size.

[0069] The present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail for better understanding of the present invention, and are not necessarily limited to those having all the configurations described. The scope of the present invention is indicated by the claims, and it is intended that all changes within the meaning and scope equivalent to the claims are included.

Explanation of Signs

[0070] 1: Burner device for cement kiln 2: Cement kiln 3: Clinker cooler 4: Kiln hood 4a: Downstream side wall surface 5: Cement clinker 7: Flow path for combustible waste fuel 8: Flow path for solid powder fuel 10: First air flow path 10c: Virtual circle 11: First opening 12: Second opening 20: Second air flow path 30: Third air flow path 40: Cement kiln model 41: First end 42: Second end 52: Secondary air AA1: Atmosphere AA2: Secondary air C1: Solid powder fuel R1: Combustible waste fuel

Claims

1. A burner device for a cement kiln, comprising a plurality of flow paths partitioned by a plurality of concentric cylindrical members, a flow path for solid powder fuel through which the solid powder fuel flows, a flow path for combustible waste fuel through which the combustible waste fuel flows, and a first air flow path located in the outermost shell, outside the flow path for solid powder fuel and the flow path for combustible waste fuel. The first air flow path is configured such that a first opening and a second opening having a relatively larger opening area than the first opening are alternately arranged at intervals in the circumferential direction. A burner device for a cement kiln, characterized in that the opening area of the second opening is larger than 1 times and not more than 4 times the opening area of the first opening.

2. Both the first opening and the second opening exhibit a circular shape whose centers are substantially located on the same virtual circle. The burner device for a cement kiln according to Claim 1, characterized in that the opening ratio, which is the ratio of the total length passing through the first opening and the second opening to the circumferential length of the virtual circle, is 10% to 40%.

3. The burner device for a cement kiln according to Claim 1 or 2, characterized in that the flow path for combustible waste fuel is located in the innermost shell.

4. an annular second air flow path located outside the flow path for combustible waste fuel and inside the flow path for solid powder fuel, and an annular third air flow path located outside the flow path for solid powder fuel and inside the first air flow path. The burner device for a cement kiln according to Claim 3 is characterized by comprising the above.

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