WO2012026422A1 - 竪型ローラミル - Google Patents
竪型ローラミル Download PDFInfo
- Publication number
- WO2012026422A1 WO2012026422A1 PCT/JP2011/068868 JP2011068868W WO2012026422A1 WO 2012026422 A1 WO2012026422 A1 WO 2012026422A1 JP 2011068868 W JP2011068868 W JP 2011068868W WO 2012026422 A1 WO2012026422 A1 WO 2012026422A1
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- WO
- WIPO (PCT)
- Prior art keywords
- fixed blade
- conical member
- lower side
- gas
- roller mill
- Prior art date
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C23/00—Auxiliary methods or auxiliary devices or accessories specially adapted for crushing or disintegrating not provided for in preceding groups or not specially adapted to apparatus covered by a single preceding group
- B02C23/08—Separating or sorting of material, associated with crushing or disintegrating
- B02C23/10—Separating or sorting of material, associated with crushing or disintegrating with separator arranged in discharge path of crushing or disintegrating zone
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
- B07B7/00—Selective separation of solid materials carried by, or dispersed in, gas currents
- B07B7/02—Selective separation of solid materials carried by, or dispersed in, gas currents by reversal of direction of flow
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C15/00—Disintegrating by milling members in the form of rollers or balls co-operating with rings or discs
- B02C15/04—Mills with pressed pendularly-mounted rollers, e.g. spring pressed
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
- B07B7/00—Selective separation of solid materials carried by, or dispersed in, gas currents
- B07B7/08—Selective separation of solid materials carried by, or dispersed in, gas currents using centrifugal force
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K3/00—Feeding or distributing of lump or pulverulent fuel to combustion apparatus
- F23K3/02—Pneumatic feeding arrangements, i.e. by air blast
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C15/00—Disintegrating by milling members in the form of rollers or balls co-operating with rings or discs
- B02C2015/002—Disintegrating by milling members in the form of rollers or balls co-operating with rings or discs combined with a classifier
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K2201/00—Pretreatment of solid fuel
- F23K2201/10—Pulverizing
- F23K2201/101—Pulverizing to a specific particle size
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K2201/00—Pretreatment of solid fuel
- F23K2201/30—Separating
Definitions
- the present invention relates to a vertical roller mill applied to, for example, a pulverized coal-fired boiler.
- raw material coal is charged from a coal charging pipe 14 into a pulverized coal machine such as a vertical roller mill 10 shown in FIGS. 9 and 10, and pulverized pulverized coal is used as a fuel.
- a pulverized coal machine such as a vertical roller mill 10 shown in FIGS. 9 and 10
- pulverized pulverized coal is used as a fuel.
- the grinding roller 13 turns while rotating on the grinding table 12 installed at the lower part in the casing 11.
- the raw material carbon introduced into the vertical roller mill 10 is pulverized by being caught between the pulverizing table 12 and the pulverizing roller 13 to be pulverized coal.
- Pulverized coal is air-fed and transported by the hot air jetted from the throat 15 disposed around the grinding table 12 to the stationary classifier 20 disposed above in the casing 11 while being dried. At this time, coarse particles having a large particle size are dropped by gravity and returned to the top of the pulverizing table 12 by gravity classification, so pulverized coal is repeatedly crushed until it has a desired particle size. .
- pulverized coal of product particles containing coarse particles is further classified by the stationary type classifier 20 disposed on the top of the grinding table 12.
- the stationary type classifier 20 in addition to the stationary classifier 20, there is a combined rotary and stationary / rotational type.
- the rotary classifier performs classification by collision and inertia force by the rotating blades, and is known to have high classification performance.
- Pulverized coal transported by air flow is dried by hot air and further classified by passing through the stationary classifier 20.
- the classified pulverized coal passes through the pulverized coal outlet 16 communicating with the inside of the fixed classifier 20 from the inside of the casing 11 to the upper side, and is airflow-fed to a boiler (not shown) by the primary air for transportation. Ru.
- the fixed classifier 20 is provided with a large number of fixed blade inlet windows 22 that are equally spaced in the circumferential direction on the upper end side of the cone 21.
- the fixed blade inlet window 22 is an opening provided through the wall surface forming the cone 21 and a flow (hereinafter referred to as "solid-gas two-phase flow") for conveying pulverized coal by air passes through it. And the inlet and the flow passage into the inside of the cone 21.
- solid-gas two-phase flow a flow for conveying pulverized coal by air passes through it.
- solid-gas two-phase flow for conveying pulverized coal by air passes through it.
- the inlet and the flow passage into the inside of the cone 21 On the inner wall side of the cone 21, fixed vanes 23 which are paired with the respective fixed vane inlet windows 22 are attached.
- an inner cylinder 24 which forms a wall surface facing the fixed blade inlet window 22 and the fixed blade 23.
- the stationary vanes 23 are all mounted in the same direction in an inclined manner, that is, with an inclination angle to a radial line toward the axial center of the cone 21 in order to impart a swirl to the solid-gas two-phase flow There is. Therefore, if the inclination angle of the fixed blade 23 is increased or decreased, the strength of the swirling flow is also changed in accordance with the opening degree (angle) of the fixed blade 23, and the fineness of classification can be adjusted.
- the lower end portion of the cone 21 is a cone outlet 25 that supplies coarse particles classified by the stationary classifier 20 onto the crushing table 12.
- the accuracy of classification in the coarse particle area is poor, and coarse particles in pulverized coal (coarse particles exceeding 100 mesh which adversely affect the combustibility) increase, so the combustion exhaust gas discharged from the boiler It becomes a factor to increase the unburned component contained in the gas.
- the solid-gas two-phase flow passing between the stationary vane inlet window 22 and between the adjacent stationary vanes 23 centrifugally classifies the particles of pulverized coal into coarse particles and fine particles by swirling flow. Thereafter, the fine powder having a small particle size and light weight is wound up on the reverse rising flow from below the cone 21 and enters the inside of the inner cylinder 24 from the lower side of the inner cylinder 24 and the vertical roller mill 10 from the pulverized coal outlet 16. Leak out.
- the coarse particles having a large particle size separated by centrifugal separation can not ride on the flow entering the inside of the inner cylinder 24 from the lower side of the inner cylinder 24 because of the large weight, and reach the inner wall of the cone 21. It falls below the cone 21 by gravity. The coarse particles are finally dropped onto the grinding table 12 from the cone outlet 25 opening at the lower center of the cone 21 and crushed again.
- the fixed blade of the flat plate be modified to be a corrugated blade.
- This corrugated wing collides with the air flow collision portion of the corrugated wing, even if coarse-grained coal flows in at any incident angle, when the mixed air flow that has swirled and raised with the primary air is taken in between the corrugated vanes of the fixed classifier. Since the classification is performed, classification performance of the stationary classifier is improved (for example, Patent Document 1).
- rotary blades are arranged in two stages in the rotation axis direction, and the blades on the lower stage are inclined with respect to the outer peripheral wall of the rotor Or, a swingable portion is provided at the tip of the rotary blade (for example, Patent Document 2).
- the fixed classifier 20 of the vertical roller mill 10 classifies pulverized coal crushed by centrifugal force into coarse particles and fine particles, but coarse particles (rough particles / fine particles) close to the product particle diameter
- the particle size of about 150 ⁇ m which is the middle of the unburned component, is weak in the centrifugal effect, and partly flows toward the center near the inner cylinder 24 due to fluctuations of solid-gas two-phase flow etc. Show a tendency to turn and descend at. Therefore, there is a problem that the probability that the coarse powder gets mixed in the reverse rising flow of the fine powder increases, and the classification efficiency decreases due to the increase in the amount of the coarse powder mixed in the product pulverized coal.
- the adjustment and setting of the fineness is performed by adjusting the opening degree of the stationary blade 23. That is, the centrifugal force is increased by narrowing the opening degree of the fixed blade 23 (increasing the inclination angle) to increase the fineness, and conversely, the opening angle of the fixed blade 23 is expanded (the inclination angle is decreased). Operation to reduce the particle size and reduce the fineness.
- the degree of opening of the fixed blade 23 is broadened to reduce the fineness, the coarse powder passing through the fixed blade 23 is not sufficiently classified by centrifugal separation, and therefore flows in the center direction with the fine powder and is wound up in a reverse upflow. As this becomes easier, the reduction in classification accuracy is magnified.
- the present invention has been made in view of such circumstances, and it is intended to reduce the ratio of coarse particles in product pulverized coal (the ratio of coarse particles to an extent exceeding 100 mesh which adversely affects the combustibility). It is an object to provide a vertical roller mill with a possible fixed classifier.
- the vertical roller mill of this invention employs the following means. That is, the vertical roller mill according to the present invention is a cyclone-type fixed type in which fine powder having a small particle size in a solid-gas two-phase flow, in which powder obtained by grinding solid is flowed, is classified by centrifugal force and discharged to the outside.
- the stationary classifier includes a conical member having a tapered portion located downward, and a conical member opened in the conical member so that a solid-gas two-phase flow can be obtained.
- the powder outlet for Flow of inside guided solid-gas two-phase flow of the conical member from the fixed vane entrance window are bent tip portion of the fixed blade so as to increase downward.
- the stationary blade is bent so that the flow of the solid-gas two-phase flow introduced to the inside of the conical member increases downward in the tip portion.
- the downward velocity component of the solid-gas two-phase flow introduced to the inside of the conical member is increased, and the coarser and heavier coarse particles of the fine powder in the solid-gas two-phase flow flow downward.
- the amount of coarse powder rolled up in the reverse upflow is reduced among the coarse particles flowing from the fixed blade inlet window to the inside of the conical member. Therefore, the classification accuracy of the vertical roller mill can be improved.
- the fixed blade is bent at a bending line connecting the upper side bending start point of the flat upper side and the lower side bending start point of the lower side of the flat plate, and the lower side bending start point is the conical member than the upper side bending start point. It may be located on the axial center side.
- the upper side bending starting point is at a position 0.2 or more and 0.3 or less from the fixed blade inlet window with respect to the total length of the upper side of the flat plate, and the lower side bending starting point is the entire length of the lower side of the flat shape
- the position may be 0.4 or more and 0.6 or less from the fixed blade inlet window.
- the upper side bending start point is 0.2 or more and 0.3 or less from the fixed blade inlet window with respect to the total length of the upper side of the flat plate, and the lower side bending start point is 0. It was decided to be provided and bent at a position of 4 or more and 0.6 or less. Therefore, the flow of the solid-gas two-phase flow can further increase the velocity component downward. Therefore, the classification accuracy of the vertical roller mill can be further improved.
- the upper side bending start point is 0.24 from the fixed blade inlet window to the entire length of the flat upper side, and the lower side bending start point is 0.50 from the fixed blade inlet window to the whole length of the lower side of the flat plate Is preferred.
- the line connecting the tip of the lower side of the fixed blade and the lower side bending start point is 10 ° or more and 30 ° or less with respect to the radial direction line from the fixed blade inlet window toward the axial center of the conical member
- the line connecting the tip of the upper side of the fixed blade to the start point of the upper side bend is not less than 5 ° and not more than 25 ° with respect to the line connecting the tip of the lower side of the fixed blade to the lower side bend start point. It is also possible to form an angle of
- the angle between the line connecting the upper side bending start point to the tip of the upper side and the line connecting the lower side bending start point to the lower end is 5 ° or more and 25 ° or less.
- the angle between the connecting line and the radial line from the fixed blade inlet window toward the axial center of the conical member is 10 ° or more and 30 ° or less. Therefore, the flow of solid-gas two-phase flow can increase the velocity component downward. Therefore, the classification accuracy of the vertical roller mill can be further improved.
- the angle between the upper side bending start point and the line connecting the lower side bending start point connecting the front end of the upper side to the lower end is more preferably 10 ° or more and 20 ° or less, and the lower side bending start point to the lower side
- the angle between the line connecting the tip and the radial line from the fixed blade inlet window toward the axial center of the conical member is more preferably 15 ° or more and 25 ° or less.
- the fixed blade may be divided into a plurality of steps from the fixed blade inlet window toward the axial center of the conical member and bent.
- the tip portion of the fixed blade is bent so that the flow of the solid-gas two-phase flow introduced to the inside of the conical member increases downward.
- the downward velocity component of the solid-gas two-phase flow introduced to the inside of the conical member is increased, and among the powders in the solid-gas two-phase flow, the larger and heavier coarse particles flow downward. become. Therefore, the amount of coarse powder rolled up in the reverse upflow is reduced among the coarse particles flowing from the fixed blade inlet window to the inside of the conical member. Therefore, the classification accuracy of the vertical roller mill can be improved.
- the vertical roller mill 10 shown in FIG. 9 is for producing pulverized coal which is, for example, a fuel for a pulverized coal-fired boiler (not shown).
- pulverized coal which is, for example, a fuel for a pulverized coal-fired boiler (not shown).
- raw material coal is pulverized into pulverized coal, and the pulverized coal after gravity classification is classified by the stationary classifier 20.
- the product pulverized coal which has been classified by passing through the fixed classifier 20 is discharged from the pulverized coal outlet (milled powder outlet) 16 provided on the upper part of the vertical roller mill 10 as pulverized coal fuel having a desired degree of fineness.
- the air is transported to the pulverized coal-fired boiler by the primary air.
- the configuration of the vertical roller mill 10 according to the present embodiment is the same as that of the prior art described above except for the configuration of the fixed classifier 20 described later, and therefore, the detailed description thereof will be omitted.
- the solid-gas two-phase flow for conveying the pulverized coal (powder) obtained by pulverizing the raw material coal (solid) in an air flow passes through, whereby the particle diameter is small.
- a cyclone-type fixed classifier 20 is provided at the upper portion in the casing 11 for classifying pulverized coal by centrifugal force and flowing it out to a pulverized coal burning boiler (outside).
- the stationary classifier 20 introduces solid-gas two-phase flow into the interior of the cone 21 from the stationary vane inlet window 22 opened to the cone (conical member) 21 and is mounted inside the stationary vane inlet window 22
- the solid-gas two-phase flow is swirled by the fixed vanes 23 and the small particle size small pulverized coal passes through the inside of the inner cylinder 24 from the lower end of the inner cylinder 24 provided inside the cone 21, It is configured to flow out from the pulverized coal outlet 16 provided at the upper end portion of the inner cylinder 24 to the outside of the cone 21.
- pulverized coal smaller than the desired particle size is classified on the reverse rising flow rising through the lower end of the inner cylinder 24 installed in the fixed classifier 20 and opened at the top. Flow out through the pulverized coal outlet 16.
- the pulverized coal is supplied from the fixed classifier 20 and the vertical roller mill 10 to a pulverized coal burning boiler (not shown) as product pulverized coal (pulverized coal for fuel).
- a fixed blade 23A shown in FIG. 1 is employed in place of the fixed blade 23 described above.
- the stationary blade 23A includes a stationary blade root 23a that imparts a swirling flow to the solid-gas two-phase flow that has flowed into the inside of the cone 21 from the stationary blade inlet window 22 and a stationary blade tip 23b that increases the downward velocity component of the swirling flow. Is equipped.
- the fixed classifier 20A includes a cone 21 and a concentric inner cylinder 24 disposed at a predetermined interval inside the cone 21, and is configured as a double cylindrical shape.
- a pulverized coal outlet 16 through which the classified product pulverized coal flows is provided to open at the top of the cone 21.
- the cone 21 has a conical shape whose tapered portion is located below the stationary classifier 20A.
- a cone outlet 25 for dropping the collected coarse particles to the grinding table 12 (see FIG. 9) is opened.
- the fixed blade inlet window 22 is an opening provided through the wall surface forming the cone 21, and a solid-gas two-phase flow for conveying pulverized coal by means of primary air is passed through the opening of the cone 21. It becomes an inlet and a flow path which flow inside.
- the solid-gas two-phase flow flowing into the fixed vane inlet window 22 is diverted in the direction of approximately 90 degrees from the upflow where the pulverized coal crushed on the crushing table 12 disposed at the lower part of the casing 11 is air-fed It is done.
- a fixed blade 23 ⁇ / b> A is attached at a position to be paired with each fixed blade inlet window 22.
- FIGS. 2A to 2C show enlarged views of the stationary blade 23A shown in FIG. 2A shows a front view of the fixed blade
- FIG. 2B shows a left side view of the fixed blade
- FIG. 2C shows a top view of the fixed blade.
- the fixed blade 23A is provided inside the cone 21 (see FIG. 1) and in the vicinity of the fixed blade inlet window 22.
- the fixed blade 23A has a shape in which a part of a flat plate is bent.
- the fixed blade 23A is bent in one step in the radial direction from the fixed blade inlet window 22 toward the axial center of the cone 21.
- the fixed blade 23A divided into two by bending is composed of a fixed blade root 23a on the fixed blade inlet window 22 side and a fixed blade tip (tip) 23b on the axial center side of the cone 21. Become.
- the fixed blade 23A has an upper side bending starting point (upper side bending starting point) 23c provided on a flat plate upper side (upper side of the cone 21) before bending and a lower side bending provided on a lower side (lower side of the cone 21). It is bent at a bending line 23e connecting the starting point (lower side bending starting point) 23d.
- the lower side bending starting point 23d is provided to be closer to the axial center of the cone 21 than the upper side bending starting point 23c.
- the fixed blade 23A Since the lower side bending start point 23d is provided closer to the axial center of the cone 21 than the upper side bending start point 23c, the fixed blade 23A has a trapezoidal shape when viewed from the left side as shown in FIG. 2B. Thus, the fixed blade tip 23b is bent. Thereby, the downward flow of the solid-gas two-phase flow whose swirl is given by the fixed blade root 23a is increased by the fixed blade tip 23b.
- the fixed blade root portions 23a of the fixed blades 23 are provided on the inner wall of the cone 21 with the same inclination angle in the same direction in order to impart a swirl to the solid-gas two-phase flow.
- the solid-gas two-phase flow that has flowed in from the fixed blade inlet window 22 (see FIG. 1) is axially centered so as to be substantially orthogonal to the outer wall of the inner cylinder 24. There will be no flow going in the direction.
- the fixed blade tip 23b is provided at the tip of the fixed blade 23A so that the flow of the solid-gas two-phase flow that flows into the inside of the cone 21 increases downward, the direction change of upward flow is substantially horizontal. It changes downward more than that. That is, since the stationary blade tip 23b forcibly guides and changes the solid-gas two-phase flow passing through the stationary blade tip 23b downward as shown by the arrow F in the drawing of FIG. The downward velocity component in which the solid-gas two-phase flow introduced to the blade tip 23 b flows into the inside of the cone 21 is increased.
- the solid-gas two-phase flow that has flowed into the inside of the cone 21 is substantially perpendicular to the outer wall of the inner cylinder 24
- the velocity component toward the center weakens and becomes smaller.
- the solid-gas two-phase flow in FIG. 1 forms a clockwise swirling flow. That is, the fixed blade tip 23 b is bent in the flow direction of the clockwise swirling flow.
- FIG. 3 shows a schematic view of the fixed blade 23A folded in one step.
- the length from the fixed blade inlet window 22 to the upper side bending start point 23c is L1
- the length from the fixed blade inlet window 22 to the lower side bending start point 23d is L2.
- the fixed blade tip side connecting the upper side bending start point 23c to the end in the extending direction of the upper side of the fixed blade 23A (hereinafter referred to as "the tip of the upper side") with respect to the fixed blade tip side lower side
- the inclination angle formed by the upper side (not shown) is assumed to be ⁇ 2.
- FIG. 4 shows the case where the fixed blade 23A is not bent (old knowledge), with respect to the ratio of coarse particles of 300 ⁇ m or more remaining in 50 mesh. Further, FIG. 4 shows L1 and L2 with respect to L (full length of fixed blade 23A) when fixed blade 23A is bent, inclination angle ⁇ 1 formed by L and fixed blade tip lower side, fixed lower end of fixed blade The case where the inclination angle ⁇ 2 formed by the blade tip side upper side is changed is compared.
- FIG. 5 shows the case where the fixed blade 23A is not bent (old knowledge), with respect to the proportion of fine particles of 75 ⁇ m or less which has passed 200 mesh. Further, FIG. 5 shows that L1 and L2 with respect to L when the fixed blade 23A is bent, the inclination angle ⁇ 1 formed by L and the lower end of the fixed blade, and the lower end of the fixed blade and the upper end of the fixed blade The case where the inclination angle ⁇ 2 is changed is compared.
- FIG. 6 shows the old findings shown in FIG. 4 and a graph of Example 1 and Example 2.
- the classification accuracy proportion of coarse particles of 300 ⁇ m or more
- the fixed blade tip portion 23b of the fixed blade 23A is obtained by bending the fixed blade tip portion 23b of the fixed blade 23A as in the first embodiment and the second embodiment as compared with the old knowledge. Has been improved.
- FIG. 7 shows the former findings shown in FIG. 5 and a graph of Example 1 and Example 2.
- the maximum fineness (the ratio of fine particles of 75 ⁇ m or less) is improved in Example 1 as compared to the old findings, and is decreased in Example 2 as compared to the old findings.
- FIG. 6 and FIG. 7 show that Example 1 is improved in classification accuracy and maximum fineness more than in the former findings, and Example 2 is improved in classification accuracy over the former findings. It can be seen that the maximum fineness is reduced.
- the fixed blade tip portion 23b of the fixed blade 23A is provided with the upper side bending start point 23c at a position of L1 / L of 0.2 or more and 0.3 or less, and a position of L2 / L of 0.4 or more and 0.6 or less
- the lower side bending starting point 23d is provided on the lower side, and the inclination angle ⁇ 1 of the lower side of the fixed blade tip side with respect to the radial direction from the fixed blade inlet window 22 toward the axial center of the cone 21 is 10 ° or more and 30 ° or less It was decided to bend so that inclination angle theta 2 between fixed blade tip side lower side may be 5 degrees or more and 25 degrees or less.
- the inclination angle ⁇ 1 is more preferably 15 ° or more and 25 ° or less, and the inclination angle ⁇ 2 is more preferably 10 ° or more and 20 ° or less. Further, it is preferable that L1 / L is 0.24 for the upper side bending start point 23c, and a position of L2 / L is 0.50 for the lower side bending start point 23d.
- the fixed blade tip portion (tip portion) 23b of the fixed blade 23A is bent so that the flow of the solid-gas two-phase flow introduced to the inside of the cone (conical member) 21 increases downward.
- the flow of the solid-gas two-phase flow introduced to the inside of the cone (conical member) 21 increases its velocity component downward, and among the fine powder in the solid-gas two-phase flow, the coarser and heavier coarse particles It flows downward inside the cone 21. Therefore, the amount of coarse powder rolled up in the reverse rising flow is reduced among the coarse particles flowing from the fixed blade inlet window 22 to the inside of the cone 21. Therefore, the classification accuracy of the vertical roller mill 10 can be improved.
- the fixed blade 23A is used. Thereby, the flow of the solid-gas two-phase flow introduced from the fixed blade inlet window 22 to the inside of the cone 21 can increase the velocity component downward. Therefore, among the fine powder in the solid-gas two-phase flow, the larger and heavier coarse particles flow downward, and the reverse upward flow of the coarse particles flowing from the fixed blade inlet window 22 toward the axial center of the cone 21 The amount to be rolled up is reduced. Therefore, the classification accuracy of the vertical roller mill 10 can be improved.
- the upper side bending point 23c of the fixed blade 23A is 0.2 or more and 0.3 or less from the fixed blade inlet window 22 with respect to the total length L of the upper side of the flat plate, and the lower side of the lower side bending starting point 23d of the fixed blade 23A is a flat plate It is provided and bent from the fixed blade inlet window 22 at a position of 0.4 or more and 0.6 or less with respect to the total length L of the lower side of the shape. Therefore, the flow of the solid-gas two-phase flow can further increase the velocity component downward. Therefore, the classification accuracy of the vertical roller mill 10 can be further improved.
- the inclination angle ⁇ 1 between the fixed blade tip side lower side (the line connecting the lower side bending start point 23d to the lower end portion 23g) and the radial direction line from the fixed blade inlet window 22 to the axial center of the cone 21 is 10
- the angle between the fixed blade tip side upper side (the line connecting the upper side bending start point 23c to the top edge 23f) and the fixed blade tip side lower side is 5 ° to 25 °
- the fixed blade tip 23b is bent so as to be as follows. Therefore, the flow of solid-gas two-phase flow can increase the velocity component downward. Therefore, the classification accuracy of the vertical roller mill 10 can be further improved.
- FIG. 8A to 8C are enlarged views of a stationary classifier of a vertical roller mill according to a second embodiment of the present invention, FIG. 8A is a front view thereof, FIG. 8B is a left side view thereof, and FIG. , Its top view is shown.
- the fixed blade 23B is composed of a fixed blade root 23a, a fixed blade first tip 23h, and a fixed blade second tip 23j.
- the fixed blade 23B is divided into two stages in the order of the fixed blade first tip 23h and the fixed blade second tip 23j in the radial direction from the fixed blade root 23a toward the axial center of the cone (not shown) and bent It is done.
- the vertical roller mill according to the present embodiment exhibits the following effects.
- the fixed blade first tip 23 h and the fixed blade second tip are divided and bent in two steps (multiple steps) from the fixed blade inlet window (not shown) toward the axial center of the cone (conical member)
- the fixed blade 23B having the portion 23j is used. Therefore, the flow of the solid-gas two-phase flow can be increased downward as compared to the case where the fixed blade 23B is bent in one step. Therefore, the classification accuracy of the vertical roller mill (not shown) can be further improved.
- the fixed blade is described as being bent in two stages, but the present invention is not limited to this, and may be bent in two or more stages.
Abstract
Description
なお、コーン21の下端部は、固定式分級器20によって分級された粗粒を粉砕テーブル12上へ供給するコーン出口25となっている。
すなわち、本発明に係る竪型ローラミルは、固体を粉砕した粉体が気流搬送された固気二相流中の粒径の小さい微粉を遠心力により分級して外部へ流出させるサイクロン型の固定式分級器をケーシング内に備える竪型ローラミルにおいて、前記固定式分級器は、先細部が下方に位置する円錐状部材と、該円錐状部材に開口しており固気二相流を該円錐状部材の内部に導入する固定羽根入口窓と、前記円錐状部材の内側であって前記固定羽根入口窓の近傍に取り付けられて固気二相流に旋回を与える平板状の固定羽根と、前記円錐状部材の軸中心に設けられて固気二相流の旋回によって微粉が下端部から上端部へと導かれる内筒と、該内筒の上端部に導かれた微粉を前記円錐状部材の外部へと導出する微粉出口と、を備え、前記固定羽根は、前記固定羽根入口窓から前記円錐状部材の内部に導かれた固気二相流の流れが下方向に増すように前記固定羽根の先端部が折り曲げられる。
なお、上辺曲げ起点は、平板状の上辺の全長に対して固定羽根入口窓から0.24に、下辺曲げ起点は、平板状の下辺の全長に対して固定羽根入口窓から0.50の位置が好適である。
なお、上辺曲げ起点から上辺の先端部を結ぶ線下辺曲げ起点から下辺の先端部までを結ぶ線と成す角度は、10°以上20°以下であれば更に好適であり、下辺曲げ起点から下辺の先端部を結ぶ線と固定羽根入口窓から円錐状部材の軸中心に向かう半径方向の線とが成す角度は、15°以上25°以下であれば更に好適である。
図9に示す竪型ローラミル10は、たとえば微粉炭焚きボイラ(図示せず)の燃料となる微粉炭を製造するものである。竪型ローラミル10は、原料炭を粉砕して微粉炭とし、重力分級後の微粉炭を固定式分級器20により分級する。これにより、固定式分級器20を通過して分級された製品微粉炭は、所望の微粉度を有する微粉炭燃料として竪型ローラミル10の上部に設けられている微粉炭出口(微粉出口)16から、1次空気により微粉炭焚きボイラへと気流搬送される。
なお、本実施形態に係る竪型ローラミル10の構成は、後述する固定式分級器20の構成を除いて上述した従来技術と同様であり、従って、その詳細な説明は省略する。
換言すれば、所望の粒径より小さい微粉炭は、固定式分級器20内に設置されている内筒24の下端部を通過して上昇する反転上昇流に乗って分級され、上部に開口している微粉炭出口16を通って流出する。この微粉炭は、固定式分級器20及び竪型ローラミル10から微粉炭焚きボイラ(図示せず)へ製品微粉炭(燃料用微粉炭)として供給される。
本実施形態では、上述した固定羽根23に代えて、図1に示す固定羽根23Aが採用されている。固定羽根23Aは、固定羽根入口窓22からコーン21の内部に流れ込んだ固気二相流に旋回流れを与える固定羽根根元部23aと旋回流れの下方向の速度成分を増す固定羽根先端部23bとを備えている。
図2Aは、固定羽根の正面図、図2Bは、固定羽根の左側面図、図2Cは、固定羽根の上面図を示している。
固定羽根23Aは、コーン21(図1参照)の内側であって固定羽根入口窓22の近傍に設けられている。固定羽根23Aは、平板状の一部を折り曲げた形状となっている。固定羽根23Aは、固定羽根入口窓22からコーン21の軸中心に向かう半径方向に1段に折り曲げられている。折り曲げられることによって2つに分割された固定羽根23Aは、固定羽根入口窓22側である固定羽根根元部23aと、コーン21の軸中心側である固定羽根先端部(先端部)23bと、からなる。
図3には、1段に折り曲げられている固定羽根23Aの模式図が示されている。
固定羽根23Aを折り曲げなかった場合、すなわち、平板状の場合における固定羽根入口窓22(図1参照)からコーン21(図1参照)の軸中心に向かう固定羽根23Aの上辺または下辺の全長をLとする。固定羽根入口窓22から上辺折り曲げ起点23cまでの長さをL1とし、固定羽根入口窓22から下辺折り曲げ起点23dまでの長さをL2とする。
図4は、50メッシュに残っている300μm以上の粗粒子の割合について、固定羽根23Aを折り曲げなかった場合(旧知見)について示している。さらに、図4は、固定羽根23Aを折り曲げた場合におけるL(固定羽根23Aの全長)に対するL1およびL2と、Lと固定羽根先端側下辺とが成す傾斜角度θ1と、固定羽根先端側下辺と固定羽根先端側上辺とが成す傾斜角度θ2とを変化させた場合を比較している。
図6に示すように、分級精度(300μm以上の粗粒子の割合)は、旧知見に比べて実施例1および実施例2のように固定羽根23Aの固定羽根先端部23bを折り曲げた場合の方が改善されている。
図7に示すように、最大微粉度(75μm以下の微粒子の割合)は、旧知見に比べて実施例1が向上し、旧知見に比べて実施例2は低下している。
これらにより、固定羽根23Aの固定羽根先端部23bは、L1/Lが0.2以上0.3以下の位置に上辺折り曲げ起点23cを設け、L2/Lが0.4以上0.6以下の位置に下辺折り曲げ起点23dを設けることとし、固定羽根入口窓22からコーン21の軸中心に向かう半径方向に対する固定羽根先端側下辺の傾斜角度θ1を10°以上30°以下とし、固定羽根先端側上辺と固定羽根先端側下辺との間の傾斜角度θ2を5°以上25°以下になるように折り曲げることとした。
また、上辺折り曲げ起点23cは、L1/Lが0.24であり、下辺折り曲げ起点23dは、L2/Lが0.50の位置が好適である。
コーン(円錐状部材)21の内部に導かれた固気二相流の流れが下方向に増すように固定羽根23Aの固定羽根先端部(先端部)23bを折り曲げることとした。これにより、コーン(円錐状部材)21の内部に導かれた固気二相流の流れが下方向に速度成分を増し、固気二相流中の微粉のうち粒子径が大きく重い粗粉ほどコーン21の内部を下方向に流れるようになる。そのため、固定羽根入口窓22からコーン21の内側へと流れ込んだ粗粉のうち反転上昇流に巻き上げられる粗粉の量が低減する。したがって、竪型ローラミル10の分級精度を向上させることができる。
以下、本発明の第2実施形態について説明する。本実施形態の竪型ローラミルは、固定羽根が2段に折り曲げられている点で第1実施形態と相違しその他は同様である。したがって、同一の構成および同一の流れについては、同一の符号を付してその説明を省略する。
図8Aから図8Cは、本発明の第2実施形態に係る竪型ローラミルの固定式分級器の拡大図であり、図8Aは、その正面図、図8Bは、その左側面図、図8Cは、その上面図を示している。
固定羽根23Bは、固定羽根根元部23aと、固定羽根第1先端部23hと、固定羽根第2先端部23jとからなっている。固定羽根23Bは、固定羽根根元部23aからコーン(図示せず)の軸中心に向かって半径方向に固定羽根第1先端部23h、固定羽根第2先端部23jの順に2段に分割されて折り曲げられている。
固定羽根入口窓(図示せず)からコーン(円錐状部材)の軸中心へと向かって2段(複数段)に分割されて折り曲げられている固定羽根第1先端部23hおよび固定羽根第2先端部23jを有している固定羽根23Bを用いることとした。そのため、固定羽根23Bが1段に折り曲げられている場合に比べて、固気二相流の流れが下方向に増加することができる。したがって、竪型ローラミル(図示せず)の分級精度を更に向上させることができる。
11 ケーシング
12 粉砕テーブル
13 粉砕ローラ
14 石炭投入管
15 スロート
16 微粉炭出口(微粉出口)
20、20A 固定式分級器
21 コーン(円錐状部材)
22 固定羽根入口窓
23A、23B 固定羽根
23b 固定羽根先端部(先端部)
23c 上辺折り曲げ起点(上辺曲げ起点)
23d 下辺折り曲げ起点(下辺曲げ起点)
23e 曲げ線
23f 上辺の先端部
23g 下辺の先端部
23h 固定羽根第1先端部
23j 固定羽根第2先端部
24 内筒
25 コーン出口
Claims (5)
- 固体を粉砕した粉体が気流搬送された固気二相流中の粒径の小さい微粉を遠心力により分級して外部へ流出させるサイクロン型の固定式分級器をケーシング内に備える竪型ローラミルにおいて、
前記固定式分級器は、先細部が下方に位置する円錐状部材と、該円錐状部材に開口しており固気二相流を該円錐状部材の内部に導入する固定羽根入口窓と、前記円錐状部材の内側であって前記固定羽根入口窓の近傍に取り付けられて固気二相流に旋回を与える平板状の固定羽根と、前記円錐状部材の軸中心に設けられて固気二相流の旋回によって微粉が下端部から上端部へと導かれる内筒と、該内筒の上端部に導かれた微粉を前記円錐状部材の外部へと導出する微粉出口と、を備え、
前記固定羽根は、前記固定羽根入口窓から前記円錐状部材の内部に導かれた固気二相流の流れが下方向に増すように前記固定羽根の先端部が折り曲げられる竪型ローラミル。 - 前記固定羽根は、平板状の上辺の上辺曲げ起点と平板状の下辺の下辺曲げ起点とを結ぶ曲げ線で折り曲げられ、
前記下辺曲げ起点は、前記上辺曲げ起点よりも前記円錐状部材の軸中心側に位置する請求項1に記載の竪型ローラミル。 - 前記上辺曲げ起点は、前記平板状の上辺の全長に対して固定羽根入口窓から0.2以上0.3以下の位置であり、前記下辺曲げ起点は、前記平板状の下辺の全長に対して固定羽根入口窓から0.4以上0.6以下の位置である請求項2に記載の竪型ローラミル。
- 前記固定羽根入口窓から前記円錐状部材の軸中心に向かう半径方向の線に対して、前記固定羽根の下辺の先端部と前記下辺曲げ起点とを結ぶ線が10°以上30°以下の角度を成し、
前記固定羽根の下辺の先端部と前記下辺曲げ起点とを結ぶ線に対して、前記固定羽根の上辺の先端部と前記上辺曲げ起点とを結ぶ線が5°以上25°以下の角度を成す請求項2または請求項3に記載の竪型ローラミル。 - 前記固定羽根は、前記固定羽根入口窓から前記円錐状部材の軸中心側へと向かって複数段に分割されて折り曲げられる請求項2から請求項4のいずれかに記載の竪型ローラミル。
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CN111229390A (zh) * | 2020-03-05 | 2020-06-05 | 兰溪诸葛南方水泥有限公司 | 一种可回料的立磨式选粉机 |
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