Adjustable Static Classifier

Abstract

To provide a static classifier capable of accommodating wide variation of types of raw materials and airflow rates.SOLUTION: A static classifier 100 includes a vessel 10 having an inlet 10A and an outlet 10B and having a vessel interior area 10V. A classifier chamber 40 is positioned in the vessel interior area. The classifier chamber has a plurality of openings 42 extending through a side wall of the classifier chamber into a classifier interior area 40D of the classifier chamber. The plurality of openings are configured for passing particles entrained in a gas from the vessel interior area into the classifier interior area. One or more flow restrictors are arranged with the classifier chamber. The flow restrictors are configured to establish an optimal flow velocity and direction of the particles entrained in the gas, through the static classifier.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention is directed to a static classifier for a grinding mill system, the static classifier being configured to separate different sized ground or pulverized particles and having a plurality of flow restriction means for adjusting the flow rate of particles entrained in a gas passing therethrough to maintain a sharp particle separation. [Background technology]

[0002] Grinding mills are used to crush solid materials, such as limestone and gypsum, minerals used in the production of stucco, phosphate rock, salt, biomass, coke, and coal, into fine particles. Impact hammer mills and ball race mills are typical grinding mills that can be used to crush, pulverize, dry, and flash-calcinate certain types of solid materials, such as gypsum, all in one step. Ground particles of various sizes are discharged from the grinding mill into a downstream classifier. One prior art classifier is known as a "whizzer separator," as disclosed in U.S. Pat. No. 2,108,609. Another classifier is a turbine classifier. One prior art classifier can be used for classifying fine particles.

[0003] The efficiency of a classifier depends on the airflow through it and the type of material being classified. Prior art static classifiers are limited to specific airflows and velocities based on the classifier's physical structure. Therefore, different classifiers are typically used to classify different materials, and a single classifier cannot be used to classify a wide range of materials, such as natural and synthetic gypsum (FGD). To produce the same amount of stucco for wallboard production, calcining FGD requires significantly more airflow than calcining natural gypsum due to the higher moisture levels in the raw material. Over the past decade, gypsum sources have changed significantly as coal-fired power plants have closed in Western countries. At the same time, developing countries are still building coal-fired power plants, and more FGD raw materials will become available in the future. This means that an ideal new calcination system must be able to accommodate a wide variety of raw material types and airflow rates.

[0004] Therefore, there is a need for an improved classifier that addresses the aforementioned problems. Summary of the Invention

[0005] Disclosed herein is a static classifier including a vessel having an inlet and an outlet and a vessel interior region. The static classifier includes a classifier chamber positioned within the vessel interior region. The classifier chamber has a plurality of openings extending through a sidewall of the classifier chamber into the classifier interior region of the classifier chamber. Each of the plurality of openings is configured to allow particles entrained in a gas to pass from the vessel interior region to the classifier interior region. The static classifier includes one or more flow restrictors disposed with the classifier chamber. The one or more flow restrictors are configured to establish a flow velocity of the particles entrained in the gas through the static classifier. Each of the plurality of openings has an axial extent. The classifier chamber includes a classifier outlet connected to an outlet duct. The flow restrictor includes a sleeve movably positioned within the outlet duct, the distal end of the sleeve extending into the classifier interior region and partially covering the axial extent.

[0006] In certain embodiments, the static classifier includes an actuator system in communication with the sleeve, the actuator system configured to axially position the sleeve relative to the plurality of openings.

[0007] In a particular embodiment, the actuator system is mounted on an outer portion of the outlet duct, with a portion of the actuator system extending through a slot in the outlet duct and secured to the sleeve.

[0008] In certain embodiments, the static classifier includes a first seal positioned radially between the sleeve and the outlet duct and having a portion axially disposed below the slot, and a second seal positioned radially between the sleeve and the outlet duct and having a portion axially disposed above the slot.

[0009] In certain embodiments, the actuator system is a rack and pinion device.

[0010] In certain embodiments, the actuator system includes a first actuator positioned on a first side of the duct and a second actuator positioned on a second side of the duct, the first and second actuators synchronously coupled to axially move the sleeve.

[0011] In certain embodiments, the first actuator is a first screw jack and the second actuator is a second screw jack, and the synchronous linkage system includes (i) a drive gearbox coupled to the first screw jack via a first linkage, (ii) a driven gearbox coupled to the second screw jack via a second linkage, and (iii) a third linkage coupling the drive gearbox to the driven gearbox.

[0012] In certain embodiments, the first actuator is a first linear actuator and the second actuator is a second linear actuator, and the first linear actuator and the second linear actuator are synchronously coupled via an electronic system.

[0013] In certain embodiments, a second flow restrictor in the static classifier includes a vane pivotally positioned in the sidewall of the classifier chamber adjacent each of the plurality of openings.

[0014] In certain embodiments, each of the plurality of openings has an axial extent and a circumferential extent, the vane has an axial length approximately equal to the axial extent, and the vane has a circumferential arc length approximately equal to the circumferential extent.

[0015] In certain embodiments, there is a vane actuator system in communication with the vane.

[0016] In certain embodiments, the classifier chamber has a top plate fixed thereto, each of the vanes is pivotally mounted on a shaft extending through the top plate, the vane actuator system includes a linkage system connected to each of the shafts and a vane actuator connected to the linkage system, and the vane actuator is configured to synchronously pivot the vanes relative to the sidewall of the classifier chamber.

[0017] In certain embodiments, the vane actuator includes a lever for manual operation or a motor for electric operation of the vane actuator.

[0018] Disclosed herein is a static classifier including a vessel having an inlet and an outlet and a vessel interior region. The static classifier includes a classifier chamber positioned within the vessel interior region. The classifier chamber has a plurality of openings extending through a sidewall of the classifier chamber into the classifier interior region of the classifier chamber. The plurality of openings are configured to allow particles entrained in a gas to pass from the vessel interior region to the classifier interior region. The static classifier includes a first flow restrictor and a second flow restrictor, respectively, disposed with the classifier chamber. The first flow restrictor and the second flow restrictor are each configured to establish a flow velocity of the particles entrained in the gas through the static classifier. The first flow restrictor includes one or more covers removably secured over one or more of the plurality of openings. The second flow restrictor includes one or more vanes pivotally disposed in the sidewall of the classifier chamber proximate each of the plurality of openings.

[0019] In certain embodiments, each of the plurality of openings has an axial extent and a circumferential extent, and each one of the covers extends across the circumferential extent of one or more of the plurality of openings and partially across the axial extent.

[0020] In certain embodiments, each of the plurality of openings has an axial extent and a circumferential extent, and each of the vanes has an axial length approximately equal to the axial extent and a circumferential arc length approximately equal to the circumferential extent.

[0021] In certain embodiments, the static classifier includes a vane actuator system in communication with the vanes.

[0022] In certain embodiments, the classifier chamber has a top plate fixed thereto, each of the vanes is pivotally mounted on a shaft extending through the top plate, the vane actuator system includes a linkage system connected to each of the shafts, and a vane actuator connected to the linkage system, the vane actuator configured to synchronously pivot the vanes relative to the sidewall of the classifier chamber.

[0023] In certain embodiments, the vane actuator includes a lever for manual operation or a motor for electric operation of the vane actuator.

[0024] In certain embodiments, each of the plurality of openings has an axial extent, the classifier chamber includes a classifier outlet connected to an outlet duct, and the static classifier further includes a third flow restrictor configured as a sleeve movably positioned within the outlet duct, a distal end of the sleeve extending into the classifier interior region and partially covering the axial extent.

[0025] In certain embodiments, an actuator system is in communication with the sleeve, the actuator system being configured to axially position the sleeve relative to the plurality of openings.

[0026] In certain embodiments, the actuator system is attached to an outer portion of the outlet duct, and a part of the actuator system (eg, an arm) extends through a slot in the outlet duct and is secured to the sleeve.

[0027] In certain embodiments, a first seal has a portion positioned radially between the sleeve and the outlet duct and axially disposed below the slot, and a second seal has a portion positioned radially between the sleeve and the outlet duct and axially disposed above the slot.

[0028] In certain embodiments, the actuator system is a rack and pinion device.

[0029] In certain embodiments, the actuator system includes a first actuator positioned on a first side of the duct and a second actuator positioned on a second side of the duct, the first and second actuators synchronously coupled to axially move the sleeve.

[0030] In certain embodiments, the first actuator is a first screw jack and the second actuator is a second screw jack, and the synchronous linkage system includes (i) a drive gearbox coupled to the first screw jack via a first linkage, (ii) a driven gearbox coupled to the second screw jack via a second linkage, and (iii) a third linkage coupling the drive gearbox to the driven gearbox.

[0031] In certain embodiments, the first actuator comprises a first linear actuator and the second actuator comprises a second linear actuator, the first linear actuator and the second linear actuator being synchronously coupled via an electronic system.

[0032] Disclosed herein is a static classifier including a vessel having an inlet and an outlet and a vessel interior region. A classifier chamber is positioned within the vessel interior region. The classifier chamber has a plurality of openings extending through a sidewall of the classifier chamber into the classifier interior region of the classifier chamber. The plurality of openings are configured to allow particles entrained in a gas to pass from the vessel interior region to the classifier interior region. At least one flow restrictor is disposed with the classifier chamber. The at least one flow restrictor is configured to establish a flow velocity and direction of the particles entrained in the gas within the static classifier.

[0033] In certain embodiments, the at least one flow restrictor includes a cover removably secured over a respective one of the plurality of openings, hi some embodiments, each of the plurality of openings has a cover secured thereover.

[0034] In certain embodiments, each of the plurality of openings has an axial extent and a circumferential extent, and each of the at least one cover extends across the circumferential extent and partially across the axial extent.

[0035] In certain embodiments, each of the plurality of openings has an axial extent, the classifier chamber includes a classifier outlet connected to the outlet duct, and the at least one flow restrictor includes a sleeve movably positioned within the outlet duct, a distal end of the sleeve extending into the classifier interior region and partially covering the axial extent.

[0036] In certain embodiments, a single actuator system is in communication with the sleeve, the actuator system being configured to axially position the sleeve relative to the plurality of openings. In certain embodiments, two or more actuator systems (e.g., four actuators) are in communication with the sleeve, the actuator systems being configured to axially position the sleeve relative to the plurality of openings.

[0037] In a particular embodiment, the actuator system is mounted on an outer portion of the outlet duct, with a portion of the actuator system extending through a slot in the outlet duct and secured to the sleeve.

[0038] In certain embodiments, the static classifier includes a first seal positioned radially between the sleeve and the outlet duct and having a portion axially disposed below the slot, and a second seal positioned radially between the sleeve and the outlet duct and having a portion axially disposed above the slot.

[0039] In certain embodiments, the actuator system includes a single rack and pinion device. In certain embodiments, the actuator system includes two or more rack and pinion devices.

[0040] In certain embodiments, the actuator system includes a first actuator positioned on a first side of the duct and a second actuator positioned on a second side of the duct, the first and second actuators synchronously coupled to axially move the sleeve.

[0041] In certain embodiments, the first actuator includes a first screw jack and the second actuator includes a second screw jack, and the synchronous connection includes (i) a drive gearbox connected to the first screw jack via a first linkage, (ii) a driven gearbox connected to the second screw jack via a second linkage, and (iii) a third linkage connecting the drive gearbox to the driven gearbox.

[0042] In certain embodiments, the first actuator comprises a first linear actuator and the second actuator comprises a second linear actuator, the first linear actuator and the second linear actuator are synchronously coupled, and the synchronous coupling is electronic.

[0043] In certain embodiments, the at least one flow restrictor comprises a vane pivotally positioned in the sidewall of the classifier chamber adjacent each of the plurality of openings.

[0044] In certain embodiments, each of the plurality of openings has an axial extent and a circumferential extent, and the vane has an axial length approximately equal to the axial extent and a circumferential arc length approximately equal to the circumferential extent.

[0045] In certain embodiments, the static classifier includes a vane actuator system in communication with the vanes.

[0046] In certain embodiments, the classifier chamber has a top plate fixed thereto, and each of the vanes is pivotally mounted on a shaft extending through the top plate, the vane actuator system includes a linkage system connected to each of the shafts and a vane actuator connected to the linkage system, the vane actuator configured to synchronously pivot the vanes relative to the sidewall of the classifier chamber.

[0047] In certain embodiments, the vane actuator includes a motor.

[0048] In certain embodiments, the sleeve has an outer diameter, and the outer edges of the vanes define a reference circle (R) having a reference diameter when the vanes are extended to their maximum radially inward position, the outer diameter being smaller than the reference diameter, and the distal end of the sleeve is spaced from the vanes when the sleeve extends into the classifier interior region to partially cover the axial extent.

[0049] In certain embodiments, the sleeve has an outer diameter, and the outer edges of the vanes define a reference circle having a reference diameter when the vanes are extended to their maximum radially inward position, the outer diameter being smaller than the reference diameter, and the distal end of the sleeve is spaced from the vanes when the sleeve extends into the classifier interior region to partially cover the axial extent.

[0050] In a particular embodiment, three flow restrictors are used, including the cover, the sleeve, and the vane.

[0051] In certain embodiments, only two flow restrictors are used: the sleeve and the vane.

[0052] In certain embodiments, only two flow restrictors are used: the cover and the vane. [Brief explanation of the drawings]

[0053] [Figure 1] FIG. 1 is a cross-sectional view of a static classifier of the present invention using a single actuator for sleeve movement.

[0054] [Figure 2A] FIG. 2A is a top cross-sectional view of the static classifier of FIG. 1 taken along section AA.

[0055] [Figure 2B] FIG. 2B is a top cross-sectional view of the static classifier of FIG. 1 taken along section BB.

[0056] [Figure 2C] FIG. 2C is an enlarged cross-sectional view of detail 2C of FIG. 1 of the lower seal.

[0057] [Figure 2D] FIG. 2D is a top view of a segmented seal for use in the static classifier of FIGS.

[0058] [Figure 2E] FIG. 2E is an enlarged cross-sectional view of detail 2E of FIG. 1 of the top seal of FIG. 2G and of the top and bottom seals.

[0059] [Figure 2F] FIG. 2F is a top view of a complete circular seal for use in the upper and / or lower seal configurations of Detail 2E of FIG. 1 and Detail 2C of FIG.

[0060] [Figure 2G] FIG. 2G is a perspective view of another embodiment of a multi-piece outlet duct having slots extending therethrough.

[0061] [Figure 3]FIG. 3 is a top view of the static classifier of FIG.

[0062] [Figure 4] FIG. 4 is a front view of a portion of the static classifier of FIG.

[0063] [Figure 5] FIG. 5 is an enlarged view of a portion of the static classifier taken along section AA of FIG.

[0064] [Figure 6] FIG. 6 is a front view of a portion of the static classifier of FIG. 1 showing two covers positioned over openings in the classifier chamber.

[0065] [Figure 7] FIG. 7 is a top cross-sectional view of the opening in the classifier chamber along section CC of FIG.

[0066] [Figure 8A] FIG. 8A is a front view of the large cover shown in FIG.

[0067] [Figure 8B] FIG. 8B is a top cross-sectional view of the cover of FIG. 8A.

[0068] [Figure 9A] FIG. 9A is a front view of the small cover shown in FIG.

[0069] [Figure 9B] FIG. 9B is a top cross-sectional view of the cover of FIG. 9A.

[0070] [Figure 10A] FIG. 10A is a front view of a portion of a static classifier similar to that shown in FIG. 1, but of a larger size.

[0071] [Figure 10B]FIG. 10B is a top view of a portion of the static classifier of FIG. 10A showing the vanes in various rotational positions.

[0072] [Figure 10C] FIG. 10C is an enlarged cross-sectional view of the motor and actuator of one of the vanes of the large classifier.

[0073] [Figure 10D] FIG. 10D is a top view of a linkage plate for the actuator of FIG. 10C.

[0074] [Figure 10E] FIG. 10E is a connector tube for the actuator of FIG. 10C.

[0075] [Figure 10F] FIG. 10F is a top view of the connector tube of FIG. 10E.

[0076] [Figure 11A] FIG. 11A is a cross-sectional view of a portion of a static classifier showing two screw jack actuators in communication with the sleeve, one half shown extended and the other half shown retracted.

[0077] [Figure 11B] FIG. 11B is a top view of the two screw jacks and static classifier of FIG. 11A.

[0078] [Figure 12A] FIG. 12A is a cross-sectional view of a portion of the static classifier of a large classifier showing two linear actuators in communication with the sleeve.

[0079] [Figure 12B] FIG. 12B is an enlarged view of detail 12B of FIG. 12A.

[0080] [Figure 13] FIG. 13 is a schematic diagram of a static classifier in a pulverizer system. DETAILED DESCRIPTION OF THE INVENTION

[0081] As shown in Figure 1, a static classifier of the present invention is generally designated by the numeral 100. Static classifier 100 includes a vessel 10 having an inlet 10A and an outlet 10B and having a vessel interior region 10V. Vessel 10 includes an upper drum 10D that transitions into a lower cone 10C that tapers inwardly toward inlet 10A.

[0082] The static classifier 100 includes a classifier chamber 40 (e.g., an outlet sleeve) positioned within a vessel interior region 10V inside an upper drum 10D. The classifier chamber 40 has a plurality of openings 42 (e.g., windows) that extend through a sidewall 44 of the classifier chamber 40 into the classifier interior region 40D of the classifier chamber 40. The plurality of openings 42 are configured to allow particles entrained in the gas to pass from the vessel interior region 10V to the classifier interior region 40D.

[0083] The static classifier 100 includes one or more flow restrictors, as further described herein, disposed with the classifier chamber 40. Each of the flow restrictors is configured to establish a flow velocity and / or direction of particles entrained in the gas through the static classifier 100. The number and type of flow restrictors used depends on the particle size required and the air flow rate of the system.

[0084] The static classifier 100 of the present invention is useful in that it can separate large particles from small particles. The flow restrictor helps optimize and maintain classification efficiency even when the system flow rate changes significantly due to changing process requirements.

[0085] The upper drum 10D of the classifier chamber 40 has an upper plate 40P fixed thereto. The classifier chamber 40 has a classifier outlet 46 formed in the upper plate 40P. The classifier outlet 46 is connected to an outlet duct 20 (e.g., an intake duct) through which the classified fine particles are entrained into the gas flow. and discharged through the duct outlet 22 do.

[0086] As shown in the embodiment of FIG. 6 , the flow restrictor is in the form of a cover 50 removably secured (e.g., bolted) to the sidewall 44 of the classifier chamber 40 and positioned over a portion of two of the plurality of openings 42. Each of the plurality of openings 42 has an axial extent 42A and a circumferential extent 42C. Each of the covers 50 extends across the circumferential extent 42C and partially across the axial extent 42A. For example, one of the covers 50 (the one on the left in FIG. 6 ) extends across a greater percentage of the axial extent than the other cover 50 (the one on the right in FIG. 6 ). While only two covers 50 are shown positioned over one opening 42 each, the covers 50 may be larger or smaller than shown herein, depending on the required flow rate and particle separation size, and the invention is not limited in this respect as each opening 42 may have a cover 50 secured thereto. In some embodiments, the cover 50 extends across two or more of the openings 42, or across all of the openings.

[0087] As shown in the embodiment of FIGS. 1, 2A, and 2B, the flow restrictor is in the form of a sleeve 30 that is movably positioned axially (along the longitudinal axis L) within the outlet duct 20, with the distal end 30A of the sleeve 30 extending into the classifier interior region 40D to partially cover the upper axial extent 42A of the openings 42. An actuator system 60 is in communication with the sleeve 30, e.g., a portion of the actuator system is bolted to the sleeve 30 with suitable fasteners 66. The actuator system 60 is configured to axially position the sleeve 30 relative to the plurality of openings 42. The actuator system 60 is attached to an outer portion of the outlet duct 20 using a suitable fastening system 64. A portion of the actuator system 60 (e.g., an actuator arm 62) extends through a longitudinal slot 20X in the outlet duct 20 and is secured to the sleeve 30, as shown in FIG. 2B. In the embodiment shown in Figures 1 and 2B, the actuator system 60 is a rack and pinion device 60R having a rack 68 and a hand crank 60H.

[0088] As shown in FIG. 2C , the first seal 80 has a portion positioned radially between the sleeve 30 and the outlet duct 20 and axially disposed below the slot 20X. The first seal 80 is secured to the top plate 40P inside the upper drum 10D by a plurality of fasteners 82 and a washer system 84. The first seal 80 projects radially inward from the top plate 40P and sealingly engages the outer surface 30Y of the sleeve 40 when the outer surface 30Y slidably engages the seal 80. In some embodiments, the first seal 80 is segmented and has multiple parts, as shown in FIG. 2D . In some embodiments, the second seal 80 is a complete circular part, as shown in FIG. 2F . In some embodiments, the first seal is a high-temperature resistant gasket material, such as graphite, silicone, or a fluoroelastomer (e.g., Viton®) material.

[0089] As shown in FIG. 2E, the second seal 90 has a portion positioned radially between the sleeve 30 and the outlet duct 20 and axially disposed above the slot 20X. The outlet duct 20 has a first flange 20F1 and a second flange 20F2, and the second seal 90 is secured therebetween by a plurality of fasteners 92. A portion of the seal 90 (the stationary seal) protrudes radially inward from the outlet duct 20 and sealingly engages the outer surface 30Y of the sleeve 30 when the outer surface 30Y slidably engages the seal 90. In some embodiments, the second seal 90 is segmented and has multiple parts, as shown in FIG. 2D. In some embodiments, the second seal 90 is a complete circular part. In some embodiments, the first seal is a high-temperature resistant gasket material such as graphite, silicone, or a fluoroelastomer (e.g., Viton®) material. Seals 80, 90 are useful for preventing ambient airflow leakage into the gas through slot 20X when the system is operating under negative pressure. Seals 80, 90 also prevent process particle flow from leaking into the environment when the system is operating under positive pressure.

[0090] In some embodiments, as shown in FIG. 2G, the seal 80 is removed and replaced on the multi-piece outlet duct 20, 20' with the seal 90 and flanges 20F1, 20F2 shown in FIG. 2C.

[0091] 1 and 2B illustrate a rack-and-pinion 60R actuator system 60, but the present invention is not limited in this regard, as other actuator systems 60 are encompassed by the present invention. For example, as shown in FIG. 11A, the actuator system 60 includes a first actuator 60A and a second actuator 60B. The first actuator 60A is positioned on a first side 20A of the duct 20, and the second actuator 60B is positioned on a second side 20B of the duct 20. In some embodiments, the first actuator 60A and the second actuator 60B are screw jacks. As shown in FIG. 11B, the first actuator 60A and the second actuator 60B are synchronously coupled to axially move the sleeve 30. The first actuator 60A and the second actuator 60B are synchronously connected via a drive gearbox 66A connected to the first actuator 60A via a first linkage 68A, a driven gearbox 66A connected to the second actuator 60B via a second linkage 68A, and a third linkage 68C connecting the drive gearbox 66A to the driven gearbox 66B.

[0092] As shown in FIG. 11B, the drive gearbox 66A is driven by a hand crank or motor to synchronously rotate the first linkage 68A and the third linkage 68C. Rotation of the third linkage 68C rotates the second linkage 68B via the second gearbox 66B. Rotation of the first linkage 68A causes the first actuator 60A to extend or retract the first actuator rod 60AJ disposed therewith. Rotation of the second linkage 68B causes the second actuator 60B to extend or retract the second actuator rod 60BJ disposed therewith. The first actuator rod 60AJ has a first connector arm 61A that extends through a slot 20X in the outlet duct 20 and is secured to the sleeve 30. The second actuator rod 60BJ has a second connector arm / rod 61B that extends through a slot 20X in the outlet duct 20 and extends through the entire diameter of the sleeve 30. Each of the first and second actuator rods 60AJ, 60BJ is protected by a respective pipe 60P (see FIG. 11A ) having a diameter slightly larger than the first and second actuator rods 60AJ, 60BJ. The first and second actuator rods 60AJ, 60BJ move synchronously. For clarity, the left side of FIG. 11A shows the first actuator rod 60AJ extending outward from the first actuator 60A, thereby causing the distal end 30A′ of the sleeve 30′ to extend downward to cover a portion of the opening 42. The right side of FIG. 11A shows the second actuator rod 60BJ retracted within the second actuator 60B, thereby moving the distal end 30A of the sleeve 30′ upward, thereby exposing the opening 42.

[0093] As shown in FIG. 12A, the first actuator 60A is the first linear actuator 60AL, and the second actuator 60B is the second linear actuator 60BL. The first linear actuator 60AL and the second linear actuator 60BL are electronically synchronously coupled to each other so that they extend or retract synchronously. As shown in FIG. 2B, the linear actuator 60BL has a connector arm 61B extending therefrom that communicates with (e.g., extends into) a cross member (e.g., tube) 30X secured to the sleeve 30. The cross member 30X extends across the sleeve 30 and is secured to opposing inner walls of the sleeve 30. The connector arm 61B extends through the cross member 30X and is secured to the first linear actuator 60AL.

[0094] 4 and 5, the flow restrictor is in the form of a vane 70 (e.g., having an arcuate profile) pivotally mounted (e.g., attached to a shaft 71) adjacent the sidewall 44 of the classifier chamber 40 adjacent each of the plurality of openings 42. The vane 70 has an axial length 70L approximately equal to the axial extent 42A of the openings 42, and the vane 70 has a circumferential arc length 70C approximately equal to the circumferential extent 42C of the openings 42. A control rod 71 extends from the classifier chamber 40 through the top plate 40P. Although a first linear actuator 60AL and a second actuator 60B are shown and described, more than two actuators (e.g., three, four, or more) may be used.

[0095] As shown in FIGS. 3, 10C, and 1D, a vane actuator system 70V is in communication with the vane 70. The vane actuator system 70V includes a linkage system having connector plates 74 connected to each of the shafts 71 and linkage rods 75 connecting adjacent connector plates 74. The vane actuator 72 has an actuator shaft 72X connected to one of the shafts 71 via an expandable bushing 76X attached to an actuator lever 76. Each connector plate 74 attached to the shaft 71 carrying the vane actuator 72 is connected to only one adjacent connector plate 74 by a single linkage rod 75. As shown in FIG. 3, no linkage rod 75 is provided between the shafts 71 positioned to the left of the shafts 71 carrying the vane actuator 72. The shafts 71 are supported within a mounting sleeve 77 via a bearing housed therein. The mounting sleeve 77 is fixed to the top plate 40P. The vane actuator 72 is configured to synchronously rotate the vanes 70 relative to the sidewall 44 of the classifier chamber 40 to adjust the size of the flow of particles entrained in the gas through the opening 42. The vane actuator 72 includes a motor or a hand crank. The connector plate 74 is shown, for example, as generally triangular. However, in some embodiments, the connector plate may have a rectangular shape 76, as shown, for example, in FIG. 10D. The connector plate 75 is useful for use on the shaft 71 with the vane actuator to provide greater load-carrying capability than other triangular-shaped connector plates 74.

[0096] As shown in Figure 2A, sleeve 30 has an outer diameter 30D. As shown in Figure 10B, outer edges 70G of vanes 70 define a reference circle R having a reference diameter RD when vanes 70 are extended to their maximum radially inward position. Because outer diameter 30D is smaller than reference diameter RD, distal end 30A of sleeve 30 is spaced from vanes 70 when sleeve 30 extends into classifier interior region 40D to partially cover axial extent 42A.

[0097] The static classifier 100 is useful in a grinding mill system 1000, as shown in Figure 13. The grinding system 1000 includes a grinding mill 200 (e.g., an impact mill) that supplies gas-entrained ground particles from an upstream blower and air heater system 300 to the static classifier 100 via an inlet duct 10A. Coarse rejects are classified in the classifier chamber 40 and returned to the grinding mill 200 via a return duct 40R. The classified fine particles are conveyed to a dust collector 400 with the aid of a fan system 500.

[0098] In some embodiments, the static classifier 100 includes three types of flow restrictors, including a cover 50 , a movable sleeve 30 , and an adjustable vane 70 .

[0099] In some embodiments, the static classifier 100 includes only two types of flow restrictors: the sleeve 30 and the adjustable vane 70 .

[0100] In some embodiments, the static classifier 100 includes only two types of flow restrictors: the cover 50 and the adjustable vane 70 .

[0101] The following clauses, listed as items, represent embodiments of the present invention.

[0102] Item 1. 1. A static classifier (100) comprising: a vessel (10) having an inlet (10A) and an outlet (10B) and having a vessel interior region (10V); a classifier chamber (40) positioned within the vessel interior region (10V), the classifier chamber (40) having a plurality of openings (42) extending through a sidewall (44) of the classifier chamber (40) into a classifier interior region (40D) of the classifier chamber (40), the plurality of openings (42) being configured to allow particles entrained in a gas to pass from the vessel interior region (10V) to the classifier interior region (40D); and at least one flow restrictor disposed with the classifier chamber (40), the at least one flow restrictor being configured to establish a flow velocity of the particles entrained in the gas through the static classifier (100).

[0103] Item 2. The static classifier (100) according to Item 1, wherein the at least one flow restrictor includes at least one cover (50) removably secured over at least one of the plurality of openings (42).

[0104] Item 3. The static classifier (100) according to Item 2, wherein each of the plurality of openings (42) has an axial range (42A) and a circumferential range (42C), and each one of the at least one cover (50) extends across the circumferential range (42C) of each one of the plurality of openings (42) and partially across the axial range (42A).

[0105] Item 4. A static classifier (100) according to Item 1, wherein each of the plurality of openings (42) has an axial extent (42A), the classifier chamber (40) includes a classifier outlet (46) connected to an outlet duct (20), and the at least one flow restrictor includes a sleeve (30) movably positioned within the outlet duct (20), and a distal end (30A) of the sleeve (30A) extends into the classifier interior region (40D) and partially covers the axial extent (42A).

[0106] Item 5. The static classifier (100) of claim 4, further comprising an actuator system (60) in communication with the sleeve (30), the actuator system (60) configured to axially position the sleeve (30) relative to the plurality of openings (42).

[0107] Item 6. The static classifier (100) according to Item 5, wherein the actuator system (60) is attached to an outer portion of the outlet duct (20), and a portion of the actuator system (60) extends through a slot (20X) in the outlet duct (20) and is fixed to the sleeve (30).

[0108] Item 7. The static classifier (100) according to claim 6, further comprising: a first seal (80) positioned radially between the sleeve (30) and the outlet duct (20) and having a portion axially disposed below the slot (20X); and a second seal (90) positioned radially between the sleeve (30) and the outlet duct (20) and having a portion axially disposed above the slot (20X).

[0109] Item 8. The static classifier (100) according to Item 5, wherein the actuator system (60) includes a rack and pinion device (60R).

[0110] Item 9. The static classifier (100) according to Item 5, wherein the actuator system (60) includes a first actuator (60A) positioned on a first side (20A) of the duct (20) and a second actuator (60B) positioned on a second side (20B) of the duct (20), and the first actuator (60A) and the second actuator (60B) are synchronously coupled to move the sleeve (30) in the axial direction.

[0111] Item 10. The static classifier (100) according to Item 9, wherein the first actuator (60A) includes a first screw jack, the second actuator (60B) includes a second screw jack, and the synchronous connection includes (i) a drive gearbox (66A) connected to the first screw jack (60AJ) via a first linkage (68A), (ii) a driven gearbox (66A) connected to the second screw jack (60BJ) via a second linkage (68A), and (iii) a third linkage (68C) connecting the drive gearbox (66A) to the driven gearbox (66B).

[0112] Item 11. The static classifier (100) according to Item 5, wherein the first actuator (60A) includes a first linear actuator (60AL), the second actuator (60B) includes a second linear actuator (60BL), the first linear actuator (60AL) and the second linear actuator (60BL) are synchronously coupled, and the synchronous coupling is electronic.

[0113] Item 12. The static classifier (100) described in Item 1, wherein the at least one flow restrictor includes a vane (70) pivotally disposed on the side wall (44) of the classifier chamber (40) adjacent to each of the plurality of openings (42).

[0114] Item 13. A static classifier (100) according to Item 12, wherein each of the plurality of openings (42) has an axial range (42A) and a circumferential range (42C), and the vane (70) has an axial length (70L) approximately equal to the axial range (42A) and a circumferential arc length (70C) approximately equal to the circumferential range (42C).

[0115] Item 14. The static classifier (100) according to Item 12, further comprising a vane actuator system (70V) in communication with the vane (70).

[0116] Item 15. The static classifier (100) according to Item 14, wherein the classifier chamber (40) has an upper plate (40P) fixed thereto, each of the vanes (70) is rotatably mounted on a shaft (77) extending through the upper plate (40P), the vane actuator system (70V) includes a linkage system connected to each of the shafts (77) and a vane actuator (70VA) connected to the linkage system, and the vane actuator (70VA) is configured to synchronously rotate the vanes (70) relative to the side wall (44) of the classifier chamber (40).

[0117] Item 16. The static classifier (100) according to Item 15, wherein the vane actuator (70VA) includes a lever for manual operation or a motor for electrically operating the vane actuator.

[0118] Item 17. A static classifier (100) according to item 2 and optionally item 3, removably fixed over at least one of the plurality of openings (42); (b) a sleeve (30) according to item 4 and optionally any of items 5 to 11, wherein each of the plurality of openings (42) has an axial extent (42A), the classifier chamber (40) includes a classifier outlet (46) connected to an outlet duct (20), the sleeve (30) is movably positioned within the outlet duct (20), and a distal end (30A) of the sleeve (30) extends into the classifier interior region (40D) and partially covers the axial extent (42A); and (c) a vane (70) according to item 12 and optionally any of items 13 to 16, pivotably disposed on the side wall (44) of the classifier chamber (40) adjacent to each of the plurality of openings (42).

[0119] Item 18. The static classifier (100) according to Item 17, wherein the sleeve (30) has an outer diameter (30D), the outer edge (70G) of the vane (70) defines a reference circle (R) having a reference diameter (RD) when the vane (70) is extended to its maximum radially inward position, the outer diameter (30D) being smaller than the reference diameter, and the distal end (30A) of the sleeve (30) is spaced apart from the vane (70) when the sleeve (30) extends into the classifier interior region (40D) to partially cover the axial range (42A).

[0120] Item 19. A static classifier (100) according to item 1, comprising: (a) the sleeve (30) according to item 4 and optionally any one of items 5 to 11, wherein each of the plurality of openings (42) has an axial extent (42A), the classifier chamber (40) includes a classifier outlet (46) connected to an outlet duct (20), the sleeve (30) is movably positioned within the outlet duct (20), and a distal end (30A) of the sleeve (30) extends into the classifier interior region (40D) and partially covers the axial extent (42A); and (b) a vane (70) according to item 12 and optionally any one of items 13 to 16, pivotally arranged on the side wall (44) of the classifier chamber (40) adjacent to each of the plurality of openings (42).

[0121] Item 20. The static classifier (100) according to Item 19, wherein the sleeve (30) has an outer diameter (30D), the outer edge (70G) of the vane (70) defines a reference circle (R) having a reference diameter (RD) when the vane (70) is extended to its maximum radially inward position, the outer diameter (30D) being smaller than the reference diameter, and the distal end (30A) of the sleeve (30) is spaced apart from the vane (70) when the sleeve (30) extends into the classifier interior region (40D) to partially cover the axial range (42A).

[0122] Item 21. The static classifier (100) according to item 1, comprising: (a) at least one cover (50) according to item 2 and optionally item 3 removably secured over at least one of the plurality of openings (42); and (b) a vane (70) according to item 12 and optionally any of items 13 to 16 pivotally disposed on the side wall (44) of the classifier chamber (40) adjacent to each of the plurality of openings (42).

[0123] Item 22. A static classifier comprising: a vessel having an inlet and an outlet and having a vessel interior region; a classifier chamber positioned within the vessel interior region, the classifier chamber having a plurality of openings extending through a sidewall of the classifier chamber into the classifier interior region of the classifier chamber, the plurality of openings configured to allow particles entrained in a gas to pass from the vessel interior region to the classifier interior region; and at least one flow restrictor disposed with the classifier chamber, the at least one flow restrictor configured to establish a flow rate of the particles entrained in the gas through the static classifier, each of the plurality of openings having an axial extent, the classifier chamber comprising a classifier outlet connected to an outlet duct, the at least one flow restrictor including a sleeve movably positioned within the outlet duct, a distal end of the sleeve extending into the classifier interior region and partially covering the axial extent.

[0124] Item 23. The static classifier of item 22, further comprising an actuator system in communication with the sleeve, the actuator system configured to axially position the sleeve relative to the plurality of openings.

[0125] Item 24. The static classifier according to Item 23, wherein the actuator system is attached to an outer portion of the outlet duct, and a portion of the actuator system extends through a slot in the outlet duct and is fixed to the sleeve.

[0126] Item 25. The static classifier according to Item 24, further comprising a first seal positioned between the sleeve and the outlet duct and having a portion disposed below the slot, and a second seal positioned between the sleeve and the outlet duct and having a portion disposed above the slot.

[0127] Item 26. The static classifier of item 23, wherein the actuator system comprises a rack and pinion device.

[0128] Item 27. The static classifier described in Item 23, wherein the actuator system includes a first actuator positioned on a first side of the duct and a second actuator positioned on a second side of the duct, the first actuator and the second actuator being synchronously coupled to move the sleeve in the axial direction.

[0129] Item 28. The static classifier according to Item 27, wherein the first actuator includes a first screw jack, the second actuator includes a second screw jack, and the synchronous connection includes (i) a drive gearbox connected to the first screw jack via a first linkage, (ii) a driven gearbox connected to the second screw jack via a second linkage, and (iii) a third linkage connecting the drive gearbox to the driven gearbox.

[0130] Item 29. The static classifier described in Item 23, wherein the first actuator includes a first linear actuator, the second actuator includes a second linear actuator, the first linear actuator and the second linear actuator are synchronously coupled, and the synchronous coupling is electronic.

[0131] Item 30. The static classifier of item 22, further comprising a second flow restrictor including a vane pivotally positioned in the side wall of the classifier chamber adjacent each of the plurality of openings.

[0132] Item 31. The static classifier according to Item 30, wherein each of the plurality of openings has an axial range and a circumferential range, and the vane has an axial length approximately equal to the axial range and a circumferential arc length approximately equal to the circumferential range.

[0133] Item 32. The static classifier of item 30, further comprising a vane actuator system in communication with the vanes.

[0134] Item 33. The static classifier of Item 32, wherein the classifier chamber has a top plate fixed thereto, each of the vanes is rotatably mounted on a shaft extending through the top plate, the vane actuator system includes a linkage system connected to each of the shafts and a vane actuator connected to the linkage system, and the vane actuator is configured to synchronously rotate the vanes relative to the side wall of the classifier chamber.

[0135] Item 34. The static classifier according to Item 32, wherein the vane actuator includes a lever for manual operation or a motor for electrically operating the vane actuator.

[0136] Item 35. A static classifier comprising: a vessel having an inlet and an outlet and a vessel interior region; a classifier chamber positioned within the vessel interior region, the classifier chamber having a plurality of openings extending through a sidewall of the classifier chamber into the classifier interior region of the classifier chamber, the plurality of openings configured to allow particles entrained in a gas to pass from the vessel interior region to the classifier interior region; and a first flow restrictor and a second flow restrictor respectively disposed with the classifier chamber, the first flow restrictor and the second flow restrictor each configured to establish a flow rate of the particles entrained in the gas through the static classifier, the second flow restrictor including a vane pivotally disposed on the sidewall of the classifier chamber proximate each of the plurality of openings, and the first flow restrictor including at least one cover removably secured over at least one of the plurality of openings.

[0137] Item 36. The static classifier described in Item 35, wherein each of the plurality of openings has an axial extent and a circumferential extent, and each one of the at least one cover extends across the circumferential extent of at least one of the plurality of openings and partially across the axial extent.

[0138] Item 37. The static classifier according to Item 35, wherein each of the plurality of openings has an axial range and a circumferential range, and the vane has an axial length approximately equal to the axial range and a circumferential arc length approximately equal to the circumferential range.

[0139] Item 38. The static classifier of item 35, further comprising a vane actuator system in communication with the vanes.

[0140] Item 39. The static classifier of Item 35, wherein the classifier chamber has a top plate fixed thereto, each of the vanes is rotatably mounted on a shaft extending through the top plate, the vane actuator system includes a linkage system connected to each of the shafts and a vane actuator connected to the linkage system, and the vane actuator is configured to synchronously rotate the vanes relative to the side wall of the classifier chamber.

[0141] Item 40. The static classifier according to Item 38, wherein the vane actuator includes a lever for manual operation or a motor for electrically operating the vane actuator.

[0142] Item 41. The static classifier described in Item 35, wherein each of the plurality of openings has an axial extent, the classifier chamber includes a classifier outlet connected to an outlet duct, and further includes a third flow restrictor including a sleeve movably positioned within the outlet duct and a distal end of the sleeve extending into the classifier interior region and partially covering the axial extent.

[0143] Item 42. The static classifier of item 41, further comprising an actuator system in communication with the sleeve, the actuator system configured to axially position the sleeve relative to the plurality of openings.

[0144] Item 43. The static classifier according to Item 42, wherein the actuator system is attached to an outer portion of the outlet duct, and a portion of the actuator system extends through a slot in the outlet duct and is fixed to the sleeve.

[0145] Item 44. The static classifier according to Item 43, further comprising a first seal positioned between the sleeve and the outlet duct and having a portion disposed below the slot, and a second seal positioned between the sleeve and the outlet duct and having a portion disposed above the slot.

[0146] Item 45. The static classifier according to items 43 and 21, wherein the actuator system comprises a rack and pinion device.

[0147] Item 46. The static classifier described in Item 43, wherein the actuator system comprises a first actuator positioned on a first side of the duct and a second actuator positioned on a second side of the duct, the first actuator and the second actuator being synchronously coupled to move the sleeve in the axial direction.

[0148] Item 47. The static classifier according to Item 46, wherein the first actuator includes a first screw jack, the second actuator includes a second screw jack, and the synchronous connection includes (i) a drive gearbox connected to the first screw jack via a first linkage, (ii) a driven gearbox connected to the second screw jack via a second linkage, and (iii) a third linkage connecting the drive gearbox to the driven gearbox.

[0149] Item 48. The static classifier described in Item 43, wherein the first actuator includes a first linear actuator, the second actuator includes a second linear actuator, the first linear actuator and the second linear actuator are synchronously coupled, and the synchronous coupling is electronic.

[0150] While the present invention has been shown and described with reference to specific embodiments thereof, it will be understood by those skilled in the art that various modifications may be made and equivalents may be substituted for the elements without departing from the scope of the invention. In addition, modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is not intended that the invention be limited to the specific embodiments disclosed in the above detailed description, but rather that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. A static classifier (100), comprising: a vessel (10) having an inlet (10A) and an outlet (10B) and having a vessel interior region (10V); a classifier chamber (40) positioned within the vessel interior region (10V), the classifier chamber (40) having a plurality of openings (42) extending through a sidewall (44) of the classifier chamber (40) into a classifier interior region (40D) of the classifier chamber (40), the plurality of openings (42) being configured to allow particles entrained in the gas to pass from the vessel interior region (10V) to the classifier interior region (40D); at least one flow restrictor disposed with said classifier chamber (40); Equipped with the at least one flow restrictor is configured to establish a flow rate of the particles entrained in the gas through the static classifier (100); Each of the plurality of openings (42) has an axial extent (42A), and the classifier chamber (40) includes a classifier outlet (46) connected to an outlet duct (20); the at least one flow restrictor includes a sleeve (30) movably positioned within the outlet duct (20), the distal end (30A) of the sleeve (30) extending into the classifier interior region (40D) and partially covering the axial extent (42A); The static classifier (100) further comprises an actuator system (60) in communication with the sleeve (30), the actuator system (60) configured to axially position the sleeve (30) relative to the plurality of openings (42); the actuator system (60) is attached to an outer portion of the outlet duct (20), a portion of the actuator system (60) extending through a slot (20X) in the outlet duct (70) and fixed to the sleeve (30); The static classifier (100) further comprises a first seal (80) positioned between the sleeve (30) and the outlet duct (20) and having a portion disposed below the slot (20X), and a second seal (90) positioned between the sleeve (30) and the outlet duct (20) and having a portion disposed above the slot (20X).

2. 2. The static classifier (100) of claim 1, further comprising a second flow restrictor including a vane (70) pivotally disposed on the sidewall (44) of the classifier chamber (40) adjacent each of the plurality of openings (42).

3. 3. The static classifier (100) of claim 2, wherein each of the plurality of openings (42) has a circumferential extent (42C), and the vane (70) has an axial length (70L) approximately equal to the axial extent (42A) and a circumferential arc length (70C) approximately equal to the circumferential extent (42C).

4. The static classifier (100) of claim 2, further comprising a vane actuator system (70V) in communication with the vanes (70).

5. 5. The static classifier (100) of claim 4, wherein the classifier chamber (40) has a top plate (40P) fixed thereto, each of the vanes (70) pivotally mounted on a shaft (77) extending through the top plate (40P), and the vane actuator system (70V) includes a linkage system connected to each of the shafts (77) and a vane actuator (70VA) connected to the linkage system, the vane actuator (70VA) configured to synchronously pivot the vanes (70) relative to the side wall (44) of the classifier chamber (40).

6. A static classifier (100), comprising: a vessel (10) having an inlet (10A) and an outlet (10B) and having a vessel interior region (10V); a classifier chamber (40) positioned within the vessel interior region (10V), the classifier chamber (40) having a plurality of openings (42) extending through a sidewall (44) of the classifier chamber (40) into a classifier interior region (40D) of the classifier chamber (40), the plurality of openings (40) being configured to allow particles entrained in the gas to pass from the vessel interior region (10V) to the classifier interior region (40D); a first flow restrictor and a second flow restrictor respectively disposed in the classifier chamber (40); Equipped with the first flow restrictor and the second flow restrictor are each configured to establish a flow rate of the particles entrained in the gas through the static classifier (100); the first flow restrictor includes at least one cover (50) removably secured over at least one of the plurality of openings (42); the second flow restrictor includes a vane (70) pivotally disposed on the side wall (44) of the classifier chamber (40) adjacent each of the plurality of openings (42); Each of the plurality of openings (42) has an axial extent (42A) and a circumferential extent (42C), and each one of the at least one covers (50) extends across the circumferential extent (42C) of at least one of the plurality of openings (42) and partially across the axial extent (42A).

7. 7. The static classifier (100) of claim 6, wherein each of the plurality of openings (42) has an axial extent (42A) and a circumferential extent (42C), and the vane (70) has an axial length (70L) approximately equal to the axial extent (42A) and a circumferential arc length (70C) approximately equal to the circumferential extent (42C).

8. The static classifier (100) of claim 6, further comprising a vane actuator system (70V) in communication with the vanes (70).

9. 9. The static classifier (100) of claim 8, wherein the classifier chamber (40) has a top plate (40P) fixed thereto, each of the vanes (70) pivotally mounted on a shaft (77) extending through the top plate (40P), and the vane actuator system (70V) includes a linkage system connected to each of the shafts (77) and a vane actuator (70VA) connected to the linkage system, the vane actuator (70VA) configured to synchronously pivot the vanes (70) relative to a side wall (44) of the classifier chamber (40).

10. 10. The static classifier (100) of claim 5 or 9, wherein the vane actuator (70VA) comprises a lever for manual operation or a motor for electric operation of the vane actuator (70VA).

11. 7. The static classifier (100) of claim 6, wherein each of the plurality of openings (42) has an axial extent (42A), the classifier chamber (40) includes a classifier outlet (46) connected to an outlet duct (20), and further comprises a third flow restrictor including a sleeve (30) movably positioned within the outlet duct (20) and a distal end (20A) of the sleeve (20) extending into the classifier interior region (40D) and partially covering the axial extent (42A).

12. 12. The static classifier (100) of claim 11, further comprising an actuator system (60) in communication with the sleeve (30), the actuator system (60) configured to axially position the sleeve (30) relative to the plurality of openings (42).

13. 13. The static classifier (100) of claim 1 or 12, wherein the actuator system (60) is attached to an outer portion of the outlet duct (20), and a portion of the actuator system (60) extends through a slot (20X) in the outlet duct (70) and is fixed to the sleeve (30).

14. 14. The static classifier (100) of claim 13, further comprising: a first seal (80) positioned between the sleeve (30) and the outlet duct (20) and having a portion disposed below the slot (20X); and a second seal (90) positioned between the sleeve (30) and the outlet duct (20) and having a portion disposed above the slot (20X).

15. The actuator system (60) includes a first actuator (60A) positioned on a first side of the outlet duct (20) and a second actuator (60B) positioned on a second side of the outlet duct (20); 13. The static classifier (100) of claim 1 or 12, wherein the first actuator (60A) and the second actuator (60B) are synchronously coupled to move the sleeve (30) axially.

16. The first actuator (60A) includes a first screw jack, and the second actuator (60B) includes a second screw jack, and the synchronous coupling is (i) a drive gearbox connected to the first screw jack via a first linkage; (ii) a driven gearbox connected to the second screw jack via a second linkage; (iii) a third linkage connecting the drive gearbox to the driven gearbox; The static classifier (100) of claim 15, comprising:

17. 16. The static classifier (100) of claim 15, wherein the first actuator (60A) comprises a first linear actuator, the second actuator (60B) comprises a second linear actuator, the first linear actuator and the second linear actuator are synchronously coupled, and the synchronous coupling is electronic.

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