Vertical roller mill

Abstract

In a vertical roller mill, this improves the non-uniformity of the inward airflow velocity in the separator's classification rotor. [Solution] The vertical roller mill comprises a rotary table, grinding rollers positioned on the upper surface of the rotary table, a separator for classifying the pulverized material that has been conveyed by a gas flow after grinding, and a mill casing having an exhaust port positioned above the separator. The separator includes a classifying rotor and guide vanes positioned around the classifying rotor. The guide vanes have multiple rows of guide vanes in the vertical direction. The multiple rows of guide vanes include a first-stage guide vane row having first-stage guide vanes arranged in a ring around the rotor axis around the classifying rotor, and a second-stage guide vane row having second-stage guide vanes arranged in a ring around the rotor axis around the classifying rotor, wherein the gas passage cross-sectional area in the first-stage guide vane row is smaller than the gas passage cross-sectional area in the second-stage guide vane row.

Description

Technical Field

[0001] The present disclosure relates to a vertical roller mill provided with a separator.

Background Art

[0002] Conventionally, vertical roller mills have been used for crushing solid fuels such as coal and for crushing cement raw materials such as limestone and clay. Hereinafter, the material to be crushed in the vertical roller mill is referred to as a raw material, and the crushed raw material is referred to as a crushed product. Some vertical roller mills are provided with a separator for classifying the crushed product to adjust the product particle size. Patent Document 1 discloses this type of vertical roller mill.

[0003] The vertical crusher of Patent Document 1 includes a crushing roller and a rotating table, and crushes the raw material input on the rotating table with the crushing roller, and blows up the crushed product with the gas supplied from below the rotating table and arranges it above the rotating table. It is configured to be taken out together with the gas from the upper outlet through a separator. The above separator includes a classification rotor composed of rotating blades arranged in a ring and fixed blades arranged on the outer periphery of the classification rotor and arranged in a ring, and swirls the airflow rectified by the fixed blades with the classification rotor to classify the crushed product.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described above, in a separator equipped with a classification rotor, the pulverized material is classified into fine and coarse powder by the balance between the centrifugal force generated by the rotation of the classification rotor and the suction force caused by the inward airflow passing through the classification rotor and toward the center of rotation. Therefore, the non-uniformity of the flow velocity of the inward airflow in the classification rotor (i.e., airflow deviation) affects the classification performance of the separator.

[0006] This disclosure is made in view of the above circumstances, and its purpose is to improve the non-uniformity of the inward airflow velocity in the separator's classification rotor in a vertical roller mill. [Means for solving the problem]

[0007] To solve the above problems, a vertical roller mill according to one aspect of this disclosure is provided. A rotating table and A crushing roller positioned on the upper surface of the aforementioned rotating table, A separator comprising a classifying rotor positioned above the rotating table and rotating about a rotor shaft extending in the vertical direction, and guide vanes positioned around the classifying rotor, which classifies the pulverized material that has been pulverized by the rotating table and the pulverizing rollers and then conveyed by a gas flow, The mill casing comprises the aforementioned rotating table, the aforementioned crushing roller, and the aforementioned separator, and has an exhaust port located above the separator. The guide vane includes multiple rows of guide blades in the vertical direction. The aforementioned multi-stage guide vane array includes a first-stage guide vane array having first-stage guide vanes arranged in a ring around the rotor axis around the classifying rotor, and a second-stage guide vane array having second-stage guide vanes arranged in a ring around the rotor axis around the classifying rotor, wherein the gas passage cross-sectional area in the first-stage guide vane array is smaller than the gas passage cross-sectional area in the second-stage guide vane array. [Effects of the Invention]

[0008] According to this disclosure, the non-uniformity of the inward airflow velocity in the separator's classification rotor can be improved in a vertical roller mill. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 shows a schematic configuration of a vertical roller mill according to one embodiment of the present disclosure. [Figure 2] Figure 2 is a diagram illustrating the support structure of the guide vane. [Figure 3] Figure 3 is a diagram showing the distribution of inward gas flow velocity in the vertical direction on the classification surface of the classification rotor. [Figure 4] Figure 4 shows the upper and lower guide vane rows of the first example, viewed from above. [Figure 5] Figure 5 shows the upper and lower guide vane rows, as viewed from above, in a modified version of the first example. [Figure 6] Figure 6 shows the upper and lower guide vane rows, as viewed from above, in a modified example of the second example. [Modes for carrying out the invention]

[0010] Next, embodiments of the present invention will be described with reference to the drawings.

[0011] [Outline configuration of vertical roller mill 1] Figure 1 is a schematic diagram of a vertical roller mill 1 according to one embodiment of the present disclosure. As shown in Figure 1, the vertical roller mill 1 comprises a rotary table 2, grinding rollers 3 that roll on the upper surface of the rotary table 2, and a separator 9 positioned above the rotary table 2. The rotary table 2, the plurality of grinding rollers 3, and the separator 9 are covered by a mill casing 7.

[0012] The rotary table 2 is rotationally driven by a table drive device 5 about a vertical rotation axis passing through the center of the rotary table 2. The table drive device 5 includes a mill motor 51 and a speed reducer 52 that amplifies the rotational torque of the mill motor 51 and transmits it to the rotary table 2. Raw materials are supplied onto the rotary table 2 through a raw material input chute 8. The inlet of the raw material input chute 8 is arranged outside the mill casing 7, and raw materials are quantitatively supplied to the inlet of the raw material input chute 8 by a feeder 14.

[0013] Between the outer peripheral edge of the rotary table 2 and the mill casing 7, annular or annularly arranged hot gas outlets are provided. A hot air inlet 72 arranged below the rotary table 2 of the mill casing 7 is connected to a hot gas source via piping or the like. The hot gas supplied from the hot gas source to the hot air inlet 72 blows upward from the hot gas outlets.

[0014] The plurality of grinding rollers 3 are arranged at equal angular intervals on a circumferential orbit centered on the rotation axis of the rotary table 2. In FIG. 1, two of the plurality of grinding rollers 3 are illustrated. Each of the plurality of grinding rollers 3 is resiliently pressed against the rotary table 2 by a roller pressing device 4 equipped with a drive source such as a hydraulic cylinder.

[0015] Above the rotary table 2, an inner cone 11 having a funnel shape is arranged. The discharge port of the inner cone 11 is located above the central portion of the rotary table 2. Inside the mill casing 7, above the inner cone 11, a separator 9 is arranged.

[0016] The separator 9 classifies the pulverized material conveyed by the airflow along with the rising hot gas into fine powder and coarse powder. The structure of the separator 9 will be described in detail later.

[0017] Above the separator 9, there is provided a mill outlet 71 which is an exhaust port of the mill casing 7. An exhaust passage 31 is connected to the mill outlet 71. The exhaust passage 31 is provided with a collecting device 33 for collecting the pulverized material entrained in the mill exhaust. The collecting device 33 may be, for example, a bag filter or a cyclone. Further, an exhaust fan 34 is provided in the exhaust passage 31. The flow rate of the mill exhaust can be adjusted by changing the rotational speed of this exhaust fan.

[0018] Subsequently, the pulverizing operation of the vertical roller mill 1 having the above configuration will be described. The plurality of pulverizing rollers 3 roll on the rotary table 2 following the rotation of the rotary table 2. When the raw material is supplied to the approximate center of the rotary table 2 through the raw material input chute 8, the raw material moves toward the outer edge of the rotary table 2 by the centrifugal force accompanying the rotational drive of the rotary table 2, and is bitten between the rotary table 2 and the pulverizing rollers 3 and pulverized.

[0019] The pulverized material further moves toward the outer edge of the rotary table 2 by the centrifugal force, and is dried by the hot gas blown up from around the rotary table 2 and conveyed upward by the airflow. Note that the spillage such as the pulverized material that does not ride on the airflow of the hot gas, gravel, and metal pieces falls from the outer peripheral edge of the rotary table 2 by the centrifugal force and is recovered.

[0020] The pulverized material that has risen in the mill casing 7 along with the flow of the hot gas is classified into coarse particles and fine particles by the separator 9. The fine particles classified by the separator 9 are conveyed to the mill outlet 71 by the airflow and flow out from the mill outlet 71 to the exhaust passage 31. The fine particles that have flowed out to the exhaust passage 31 are separated from the airflow by the collecting device 33 and recovered as a product. On the other hand, the coarse particles classified by the separator 9 slide down the inner cone 11 and are returned onto the rotary table 2 and pulverized again together with the raw material.

[0021] 〔Configuration of the separator 9〕 Here, the configuration of the separator 9 will be described in detail. The separator 9 comprises a classifying rotor 91, guide vanes 92 provided on the outer circumference side of the classifying rotor 91, and a separator drive device 93 that rotates the classifying rotor 91.

[0022] The classifying rotor 91 comprises a rotor shaft 94 and a rotor blade row 98C consisting of a plurality of rotor blades 98 arranged in an annular pattern around the rotor shaft 94. The rotor shaft 94 hangs down from the top of the mill casing 7 into the mill casing 7 and is rotatably supported by the mill casing 7. The rotor shaft 94 and the rotor blade row 98C are connected via a rim 95, and the rotor blade row 98C rotates integrally with the rotor shaft 94. The separator drive unit 93 is located outside the mill casing 7. The separator drive unit 93 includes a classifying motor M and a power transmission mechanism that transmits the rotation of the classifying motor M to the rotor shaft 94, and the rotor shaft 94, i.e., the classifying rotor 91, rotates when the classifying motor M is driven.

[0023] The guide vane 92 has multiple rows of guide vanes 96C, 97C in the vertical direction, including an upper guide vane row 96C and a lower guide vane row 97C. In this embodiment, the guide vane 92 has two rows of guide vanes 96C, 97C, but one or more additional rows of guide vanes may be arranged in addition to the upper guide vane row 96C and the lower guide vane row 97C.

[0024] The upper guide vane row 96C consists of multiple upper guide vanes 96 arranged in a ring around the rotor axis 94. The blade angle of the upper guide vanes 96 is variable. The lower guide vane row 97C consists of multiple lower guide vanes 97 arranged in a ring around the rotor axis 94. The blade angle of the lower guide vanes 97 is variable. Here, the blade angle represents the inclination of the chord lines of the guide vanes 96 and 97 with respect to the radial direction (i.e., the radial direction of the guide vane rows 96C and 97C) with respect to the rotor axis 94.

[0025] The blade angles of the multiple upper guide vanes 96 may be the same or different from each other. The blade angles of the multiple lower guide vanes 97 may be the same or different from each other. If the rotor blades 98 have a vertically divided structure, variations in the blade angles of the rotor blades 98 in the rotor blade row 98C may disrupt the rotational balance of the classifier rotor 91. However, since the guide vanes 96 and 97 are stationary during operation, variations in the blade angles of the guide vanes 96 and 97 in the guide vane rows 96C and 97C do not cause the above-mentioned problems.

[0026] When the number of divisions is two, the vertical dimension of the upper guide vane 96 is smaller than the vertical dimension of the lower guide vane 97. Preferably, the vertical dimension of the upper guide vane 96 is 1 / 2 or less of the vertical dimension of the guide vane 92, and more preferably 1 / 3 or less.

[0027] Figure 2 illustrates the support structure of the upper guide vane 96 and the lower guide vane 97. Although Figure 2 shows the support structure of one pair of upper guide vane 96 and lower guide vane 97, other upper guide vane 96 and lower guide vane 97 have similar support structures.

[0028] As shown in Figure 2, the upper guide vane 96 and the lower guide vane 97 are supported by the mill casing 7. An inner cylinder 82 penetrates the mill casing 7, and a support shaft 81 is rotatably inserted through this inner cylinder 82. The support shaft 81 is longer than the inner cylinder 82, and the support shaft 81 extends upward from the inner cylinder 82 and downward from the inner cylinder 82.

[0029] The lower part of the inner cylinder 82 and the portion of the support shaft 81 that extends below the inner cylinder 82 are exposed inside the milk casing 7. Inside the milk casing 7, the upper guide vane 96 is fixed to the inner cylinder 82, and the lower guide vane 97 is fixed to the support shaft 81.

[0030] An outer cylinder 83 is fixed to the outer surface of the mill casing 7, and an inner cylinder 82 is rotatably inserted into the outer cylinder 83. An upper guide plate 86 is fixed to the upper end of the outer cylinder 83. The inner cylinder 82 extends upward from the outer cylinder 83 above the upper guide plate 86, and an upper lever 84 is fixed to this extended portion of the inner cylinder 82. The upper guide plate 86 is provided with an arc-shaped guide hole 86a that guides and restricts the rotation of the upper lever 84. A bolt 88 passed through the upper lever 84 is movable within the guide hole 86a. Above the upper guide plate 86, a lower guide plate 87 is positioned via a support. The upper end of the support shaft 81 extends upward from the inner cylinder 82 above the lower guide plate 87, and a lower lever 85 is fixed to this extended portion of the support shaft 81. The lower guide plate 87 is provided with a guide hole 87a that guides and restricts the rotation of the lower lever 85. The bolt 89, which passes through the lower lever 85, is movable within the guide hole 87a of the lower guide plate 87.

[0031] When the upper lever 84 is rotated, the inner cylinder 82 rotates relative to the support shaft 81, and the upper guide vane 96 fixed to the inner cylinder 82 rotates around the support shaft 81, changing the blade angle of the upper guide vane 96. The blade angle of the upper guide vane 96 is fixed by fastening the upper lever 84 to the upper guide plate 86 with a bolt 88 and nut. Similarly, when the lower lever 85 is rotated, the support shaft 81 rotates relative to the inner cylinder 82, and the lower guide vane 97 fixed to the support shaft 81 rotates around the support shaft 81, changing the blade angle of the lower guide vane 97. The blade angle of the lower guide vane 97 is fixed by fastening the lower lever 85 to the lower guide plate 87 with a bolt 89 and nut.

[0032] In the separator 9, the blade angles of each upper guide blade 96 in the upper guide blade row 96C, and the blade angles of each lower guide blade 97 in the lower guide blade row 97C, are adjusted before operation or pre-set during the construction of the vertical roller mill 1.

[0033] In the separator 9, under the condition that the blade angles of all upper guide vanes 96 and lower guide vanes 97 are equal and that the upper guide vanes 96 and lower guide vanes 97 are treated as a single guide vane, a CFD (Computational Fluid Dynamics) analysis of the airflow flowing into the separator 9 was performed. The results revealed that the gas flow concentrates at the top of the separator 9 because it is exhausted from the mill outlet 71 located above the separator 9, and that the gas flow concentrates at the top of the separator 9 due to centrifugal force because the gas flow abruptly changes direction from upward to sideways towards the center of the classifying rotor 91 at the inlet of the separator 9.

[0034] Figure 3 is a chart showing the distribution of inward gas flow velocity in the vertical direction on the classification surface S of the classification rotor 91. The classification surface S of the classification rotor 91 is, in other words, the outer surface of the rotor blade row 98C. In this chart, the vertical axis represents the vertical position on the classification surface S, and the horizontal axis represents the inward gas flow velocity on the classification surface S. Inward gas flow velocity is the speed of the lateral gas flow from the classification surface S of the classification rotor 91 toward the center of rotation. In this chart, the relationship between the vertical position on the classification surface S and the inward gas flow velocity when all the blade angles of the upper guide blades 96 and lower guide blades 97 are equal and the upper guide blades 96 and lower guide blades 97 can be considered as a single guide blade is shown by a dashed line as a "comparative example". Furthermore, the relationship between the vertical position on the classification surface S and the inward gas flow velocity when the ratio of the vertical dimensions of the upper guide vane 96 and the lower guide vane 97 is 1:1 is shown by a solid line as an "Example". In the comparative example, as a result of the gas flow concentrating at the top of the separator 9, the gas flow is concentrated at the top of the classification rotor 91, and the inward gas flow velocity on the classification surface S of the classification rotor 91 is non-uniform in the vertical direction. More specifically, in the comparative example, the inward gas flow velocity passing through the upper part of the classification surface S of the classification rotor 91 is greater than the inward gas flow velocity passing through the lower part of the classification surface S, and there is a part at the top of the classification surface S where the inward gas flow velocity is locally higher compared to other parts.

[0035] The classification diameter of the separator 9 is adjusted by the rotational speed and airflow of the classification rotor 91. However, if there is a bias in the inward gas flow velocity on the classification surface S of the classification rotor 91, the conventional practice is to rotate the classification rotor 91 at a rotational speed that matches the largest value of the inward gas flow velocity. Consequently, if there is a bias in the inward gas flow velocity on the classification surface S of the classification rotor 91, the energy required to rotate the classification rotor 91 increases, and proper classification is not performed on the classification surface S where the inward gas flow velocity does not match the rotational speed of the classification rotor 91, resulting in a decrease in classification efficiency. Therefore, in the separator 9 according to this disclosure, the guide vanes 92 are configured in multiple stages in the vertical direction, including an upper guide vane row 96C and a lower guide vane row 97C, so that the gas passage cross-sectional area of ​​the upper guide vane row 96C is smaller than the gas passage cross-sectional area of ​​the lower guide vane row 97C. The gas passage cross-sectional area of ​​the upper guide vane row 96C is the sum of the cross-sectional areas of the passages between adjacent upper guide vanes 96, and the cross-sectional area of ​​each passage may be the smallest cross-sectional area within that passage. Similarly, the gas passage cross-sectional area of ​​the lower guide vane row 97C is the sum of the cross-sectional areas of the passages between adjacent lower guide vanes 97, and the cross-sectional area of ​​each passage may be the smallest cross-sectional area within that passage.

[0036] As described above, when the gas passage cross-sectional area of ​​the upper guide vane row 96C is smaller than the gas passage cross-sectional area of ​​the lower guide vane row 97C, the gas flows more actively towards the lower guide vane row 97C than towards the upper guide vane row 96C. In other words, because the gas passage cross-sectional area of ​​the upper guide vane row 96C is smaller than that of the lower guide vane row 97C, the upper guide vane row 96C obstructs the gas flow toward the classifying rotor 91 more than the lower guide vane row 97C. As a result, the amount of gas passing over the guide vane 92 decreases and the amount of sludge passing under the guide vane 92 increases. Therefore, as shown by the solid line in Figure 3, the vertical bias of the inward gas flow velocity on the classifying surface S of the classifying rotor 91 is reduced, and the non-uniformity of the inward gas flow velocity on the classifying surface S of the classifying rotor 91 is mitigated.

[0037] Figure 4 is a view from above of the upper guide vane row 96C and lower guide vane row 97C in the first example. In the example shown in Figure 4, the blade angles of the upper guide vane 96 and the lower guide vane 97 are different. The blade angle of the upper guide vane 96 is larger than that of the lower guide vane 97. Therefore, the inter-blade passages of the upper guide vane 96 are narrower than those of the lower guide vane 97. As a result, the gas passage cross-sectional area of ​​the upper guide vane row 96C is smaller than that of the lower guide vane row 97C. Note that the blade angles of all upper guide vanes 96 do not have to be the same. For example, as in the modified example shown in Figure 5, the blade angles of some of the upper guide vanes 96 may be the same as the planting angle of the lower guide vane 97, and the blade angles of the remaining parts may be larger than the blade angles of the lower guide vane 97. Also, some of the inter-blade passages of the upper guide vane row 96C may be closed or narrowed.

[0038] In the examples shown in Figures 4 and 5, the average blade angle of the multiple upper guide blades 96 of the upper guide blade row 96C is larger than the average blade angle of the multiple lower guide blades 97 of the lower guide blade row 97C. In this way, the narrowing of the inter-blade passages of the upper guide blade row 96C reduces the flow path cross-sectional area of ​​the upper guide blade row 96C, obstructing the gas flow passing through the upper guide blade row 96C, causing the gas flow to concentrate in the lower guide blade row 97C. Then, an upward force acts on the gas flow that has passed through the lower guide blade row 97C due to the suction force generated at the mill outlet 71, and the gas flow is dispersed in the vertical direction across the classification surface S of the classification rotor 91. As a result, the vertical bias of the inward gas flow velocity on the classification surface S of the classification rotor 91 is reduced, and the non-uniformity of the inward gas flow velocity on the classification surface S of the classification rotor 91 is mitigated.

[0039] Incidentally, due to the circumferential position of the mill outlet 71 and the presence of components that obstruct the gas flow, there may be circumferential biases or locally high points in the inward gas flow velocity on the classification surface S of the classification rotor 91. When there is a localized flow bias R1 where the gas flow is concentrated in the circumferential direction, the blade angle of the lower guide vane 97 is adjusted in the guide vane 92 so that the gas flow toward the classification rotor 91 at the circumferential flow bias R1 is significantly obstructed compared to other locations. Here, the blade angle of the upper guide vane 96 may also be adjusted in addition to the lower guide vane 97.

[0040] Figure 6 is a view from above of the upper guide vane row 96C and lower guide vane row 97C in the second example. In the example shown in Figure 6, the blade angle of the lower guide vane 97 located at the circumferential flow deviation point R1 is larger than that of the other lower guide vanes 97, and the passage between the lower guide vanes 97 located at the flow deviation point R1 is closed or narrowed. In this way, by making the blade angle of the lower guide vane 97 at the flow deviation point R1 larger than that of the other lower guide vanes 97 in the lower guide vane row 97C, the gas flow passing through the flow deviation point R1 is obstructed. As a result, the circumferential bias of the inward gas flow velocity at the classification surface S of the classification rotor 91 is reduced.

[0041] In the separator 9 of the vertical roller mill 1 according to this disclosure, both the upper guide vane 96 and the lower guide vane 97 have variable blade angles, but the blade angle of at least one of the upper guide vane 96 and the lower guide vane 97 may be variable. For example, the upper guide vane 96 and the lower guide vane 97 may have fixed blade angles. Alternatively, for example, the blade angle of the upper guide vane 96 may be variable and the lower guide vane 97 may have a fixed blade angle. When a fixed blade angle is adopted in this way, the inward gas flow velocity on the classification surface S of the classification rotor 91 without the action of the guide vane 92 is predicted in advance by simulation, the fixed blade angles of the upper guide vane 96 and the lower guide vane 97 are determined based on the predicted non-uniformity of the inward gas flow velocity, and the upper guide vane 96 and the lower guide vane 97 are fixed to the mill casing 7 so that the fixed blade angles are realized.

[0042] [Summary] The vertical roller mill 1 relating to item 1 of this disclosure is Rotary table 2 and A crushing roller 3 is positioned on the upper surface of the rotating table 2, A separator 9 is positioned above the rotary table 2 and includes a classifying rotor 91 that rotates around a rotor shaft 94 extending in the vertical direction, and guide vanes 92 arranged around the classifying rotor 91, which classifies the pulverized material that has been pulverized by the rotary table 2 and the pulverizing rollers 3 and then conveyed by a gas flow, The mill casing 7 comprises a rotating table 2, a grinding roller 3, and a separator 9, and has an exhaust port located above the separator 9. The guide vane 92 includes multiple rows of guide vanes 96C, 97C in the vertical direction. The multiple-stage guide vane rows 96C, 97C include a first-stage guide vane row (corresponding to the upper guide vane row 96C in the above embodiment) having first-stage guide vanes (corresponding to the upper guide vane row 96 in the above embodiment) arranged in a ring around the rotor shaft 94 of the classifying rotor 91, and a second-stage guide vane row (corresponding to the lower guide vane row 97C in the above embodiment) having second-stage guide vanes (corresponding to the lower guide vane row 97 in the above embodiment) arranged in a ring around the rotor shaft 94 of the classifying rotor 91, characterized in that the gas passage cross-sectional area in the first-stage guide vane row is smaller than the gas passage cross-sectional area in the second-stage guide vane row.

[0043] In the vertical roller mill 1 with the above configuration, the gas flow passing through the first stage guide vane row of the guide vanes 92 is obstructed more significantly than the gas flow passing through the second stage guide vane row, so the gas flow passing through the guide vanes 92 is concentrated in the second stage guide vane row. In this way, by utilizing the difference in the size of the inter-blade passages of the guide vane row, the vertical bias of the inward gas flow velocity at the classification surface S of the classification rotor 91 can be reduced. Therefore, the vertical roller mill 1 according to the present disclosure can improve the non-uniformity of the inward airflow velocity at the classification rotor 91 of the separator 9.

[0044] The vertical roller mill 1 relating to the second item of this disclosure is characterized in that the first stage guide blade row 96C is located above the second stage guide blade row 97C.

[0045] In the vertical roller mill 1 with the above configuration, the gas that has passed through the guide vanes 92 diffuses upward due to the suction force of the mill outlet 71, resulting in a reduction of the vertical bias of the inward gas flow velocity on the classification surface S of the classification rotor 91.

[0046] The vertical roller mill 1 relating to item 3 of this disclosure is a vertical roller mill 1 relating to item 1 or 2, wherein the average blade angle of the first stage guide blade 96 of the first stage guide blade row 96C is greater than the average blade angle of the second stage guide blade 97 of the second stage guide blade row 97C.

[0047] In the vertical roller mill 1 relating to the third item, by adjusting the blade angle of the first stage guide blade 96, the gas passage cross-sectional area in the first stage guide blade row 96C can be made smaller than the gas passage cross-sectional area in the second stage guide blade row 97C.

[0048] The vertical roller mill 1 relating to item 4 of this disclosure is a vertical roller mill 1 relating to any of items 1 to 3, wherein the vertical dimension of the first stage guide blade row 96C is smaller than the vertical dimension of the second stage guide blade row 97C.

[0049] In the vertical roller mill 1 relating to the fourth item, the vertical proportion of the guide vanes 92 occupied by the first stage guide vane row 96C is suppressed. Since the passage of gas is restricted in the first stage guide vane row 96C, it is preferable that the vertical dimension of the first stage guide vane 96 be as small as possible, if it is possible to suppress the localized increase in inward gas flow velocity.

[0050] The vertical roller mill 1 relating to item 5 of this disclosure is a vertical roller mill 1 relating to any of items 1 to 4, wherein the blade angle of at least one of the first stage guide blades 96 and the second stage guide blades 97 is variable.

[0051] In the vertical roller mill 1 relating to item 5, the gas passage cross-sectional area of ​​the first stage guide blade row 96C and the gas passage cross-sectional area of ​​the lower stage guide blade row 97C can be adjusted after the separator 9 is installed. Therefore, the gas passage cross-sectional areas of the first stage guide blade row 96C and the second stage guide blade row 97C can be adjusted according to the operating conditions of the vertical roller mill 1.

[0052] The discussions of this disclosure described above are presented for illustrative and explanatory purposes only and are not intended to limit the disclosure to the forms disclosed herein. For example, in the detailed description above, various features of the disclosure are grouped into a single embodiment for the purpose of streamlining the disclosure, but some of the features may be combined. Also, some of the features included in this disclosure may be combined into alternative embodiments, configurations, or aspects other than those discussed above. [Explanation of symbols]

[0053] 1: Vertical roller mill 2: Rotating table 3: Crushing roller 7: Mill casing 9: Separator 71: Mill outlet (exhaust port) 91: Classification rotor 92: Guide vane 94: Rotor shaft 96: Upper guide vane (an example of a first-stage guide vane) 96C: Upper guide vane row (an example of a first-stage guide vane row) 96C: Guide vane row 97: Lower guide vane (an example of a second-stage guide vane) 97C: Lower guide vane row (an example of a second-stage guide vane row) 97C: Guide wing row

Claims

1. Rotating table and A crushing roller positioned on the upper surface of the aforementioned rotating table, A separator comprising a classifying rotor positioned above the rotating table and rotating about a rotor shaft extending in the vertical direction, and guide vanes positioned around the classifying rotor, which classifies the pulverized material that has been pulverized by the rotating table and the pulverizing rollers and then conveyed by a gas flow, The mill casing comprises the aforementioned rotating table, the aforementioned crushing roller, and the aforementioned separator, and has an exhaust port located above the separator. The guide vane includes multiple rows of guide blades in the vertical direction. The aforementioned multi-stage guide vane array includes a first-stage guide vane array having first-stage guide vanes arranged in an annular pattern around the rotor axis of the classifying rotor, and a second-stage guide vane array having second-stage guide vanes arranged in an annular pattern around the rotor axis of the classifying rotor, wherein the gas passage cross-sectional area in the first-stage guide vane array is smaller than the gas passage cross-sectional area in the second-stage guide vane array. Vertical roller mill.

2. The first stage guide vane row is located above the second stage guide vane row. The vertical roller mill according to claim 1.

3. The average blade angle of the first stage guide blades in the first stage guide blade row is greater than the average blade angle of the second stage guide blades in the second stage guide blade row. The vertical roller mill according to claim 1.

4. The vertical dimension of the first stage guide vane row is smaller than the vertical dimension of the second stage guide vane row. A vertical roller mill according to any one of claims 1 to 3.

5. The blade angle of at least one of the first stage guide vane and the second stage guide vane is variable. A vertical roller mill according to any one of claims 1 to 3.

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