Methods and systems for centrifugal separation and purification of dust generated during ring road reconstruction construction

Abstract

This invention relates to the field of road construction dust control technology, and discloses a centrifugal separation and purification method and system for dust generated during ring road reconstruction construction. The method includes: tangentially introducing a dust-laden airflow into a swirling space, where dust particles are separated by centrifugal force and slide off the inner wall surface for discharge; the airflow continues into an acceleration channel with a gradually decreasing cross-sectional area, where the rotational speed increases to perform secondary centrifugal separation of residual fine dust; dust particles adhering to the inner wall surface agglomerate into aggregates through rolling collisions and then settle in a settling space under gravity; the separated purified airflow is discharged in a straight-line flow state after the rotational tangential velocity component gradually decreases through an outlet channel; this invention also provides a centrifugal separation and purification system for performing the above method. This invention achieves highly efficient purification of dust-laden airflow through two-stage centrifugal separation, self-agglomeration and settling of dust on the wall surface, and airflow deswirl isolation and discharge.

Description

Technical Field

[0001] This invention relates to the field of road construction dust control technology, specifically to a centrifugal separation and purification method and system for dust generated during ring road reconstruction construction. Background Technology

[0002] During the reconstruction of ring roads, operations such as road surface breaking, milling, and paving generate a large amount of dust-laden airflow. Dust particles spread to the surrounding environment in the form of unorganized emissions. Among the existing road construction dust removal technologies, centrifugal separation is widely used due to its simple structure and low operating cost. Cyclone separators utilize the centrifugal force field generated by the change of linear motion to high-speed rotation after the dust-laden airflow enters the conical structure, which throws the dust particles against the cylinder wall, ultimately causing the dust to settle in the dust collection box.

[0003] However, existing cyclone separators have a prominent drawback in practical applications: the cyclone separator contains a tangential vortex composed of high-intensity rotating free vortices and forced vortices. Near the dust discharge port of the separator's conical section, the vortex core center often deviates from the geometric center line of the separator and undergoes a spiraling motion, causing pulsation in the flow field velocity. This results in the settled dust particles being re-entrained and entering the rotating flow field under the action of the return airflow and the vortex core oscillation, causing secondary dust entrainment. This secondary dust entrainment phenomenon causes the dust particles that have been separated from the airflow to be re-mixed into the purified airflow, severely reducing the separation efficiency. Ultimately, the dust concentration in the discharged purified airflow is still relatively high. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for centrifugal separation and purification of dust generated during ring road reconstruction construction, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for centrifugal separation and purification of dust generated during ring road reconstruction construction, comprising the following steps:

[0006] S1: The dust-laden airflow generated in the ring road reconstruction construction area is tangentially introduced into a vortex space. The dust-laden airflow rotates along the inner wall of the vortex space. During the rotation, the dust particles inside the dust-laden airflow are subjected to centrifugal force. Driven by the centrifugal force, the dust particles move towards the inner wall of the vortex space. The dust particles that move to the inner wall of the vortex space collide with the inner wall. After the collision, the dust particles lose their suspension ability and slide down along the inner wall. The dust particles that slide to the bottom of the vortex space are discharged from the vortex space through the outlet at the bottom of the vortex space.

[0007] S2: After being processed by S1, the airflow is discharged from the bottom of the vortex space and enters an acceleration channel with a flow cross-sectional area that gradually decreases along the direction of airflow. The axial velocity of the airflow in the acceleration channel increases as the flow cross-sectional area decreases. The increase in the axial velocity of the airflow drives the rotation speed of the airflow to increase synchronously. The airflow with the increased rotation speed exerts an enhanced centrifugal force on the residual dust particles carried inside the airflow. Driven by the enhanced centrifugal force, the residual dust particles migrate outward from the mainstream airflow. The residual dust particles that migrate to the inner wall of the acceleration channel adhere to the inner wall of the acceleration channel.

[0008] S3: Dust particles attached to the inner wall of the acceleration channel are dragged along the wall by the tangential drag force generated by the airflow flowing along the axial direction of the acceleration channel. During the rolling process, the dust particles collide and squeeze with each other. The collision and squeezing cause the dispersed dust particles to agglomerate into agglomerates. Under the combined action of their own gravity and the drag force of the airflow, the agglomerates continue to move along the inner wall of the acceleration channel towards the exit of the acceleration channel. The agglomerates that move to the exit of the acceleration channel leave the acceleration channel and enter a settling space. After entering the settling space, the movement speed of the agglomerates decreases. After the movement speed decreases, the agglomerates settle to the bottom of the settling space under the action of gravity.

[0009] S4: After the residual dust particles in S2 are separated, the airflow is discharged from the outlet of the acceleration channel. After being discharged, the airflow changes its flow direction at the outlet of the acceleration channel and flows along an outlet channel. The airflow direction in the outlet channel is isolated from and does not cross the settling direction of the agglomerates in the settling space. During the flow of the airflow in the outlet channel, the rotational tangential velocity component of the airflow in the outlet channel decreases step by step. The airflow after the rotational tangential velocity component decreases is discharged from the end of the outlet channel in a straight flow state.

[0010] As a preferred technical solution of the present invention, in S1, before the dust-laden airflow is tangentially introduced into the swirling space, a spiral pre-swirl operation is applied to the dust-laden airflow. The spiral pre-swirl operation changes the flow direction of the dust-laden airflow from straight flow to spiral flow. During the spiral flow process, the dust-laden airflow obtains a tangential velocity component along the tangential direction of the spiral path.

[0011] The dust-laden airflow with the tangential velocity component is then tangentially introduced into the swirling space. The tangential velocity component of the dust-laden airflow when it is introduced into the swirling space is consistent with the rotation direction of the airflow in the swirling space.

[0012] During the spiral pre-swirl operation, the magnitude of the tangential velocity component of the dust-laden airflow is adjusted by changing the spiral radius of the spiral flow. When the adjusted dust-laden airflow is introduced into the swirling space, the difference between the tangential velocity component of the dust-laden airflow and the average rotational speed of the airflow in the swirling space does not exceed the preset difference.

[0013] As a preferred technical solution of the present invention, in step S2, during the process of accelerating and rotating the airflow in the acceleration channel, compression and release operations are sequentially applied to the airflow along the axial direction of the acceleration channel, and the compression and release operations are alternately arranged along the axial direction of the acceleration channel.

[0014] The compression operation increases the static pressure of the airflow, and the dust particles in the airflow are forced against the inner wall of the acceleration channel under the action of the increased static pressure.

[0015] The release operation reduces the static pressure of the airflow, accelerating the shedding of dust particles from the inner wall of the channel under the reduced static pressure. The shed dust particles are then resuspended in the airflow and are pressed against the inner wall again during the subsequent compression operation. The dust particles pressed against the inner wall again are superimposed on the existing dust layer on the inner wall, forming a thickened dust layer. The thickened dust layer is then completely detached from the inner wall during the subsequent release operation and slides down the inner wall.

[0016] As a preferred technical solution of the present invention, in step S3, during the process of the airflow flowing along the axial direction of the acceleration channel toward the outlet of the acceleration channel, when the airflow reaches a position before the outlet of the acceleration channel, the airflow changes its axial flow direction before the outlet of the acceleration channel.

[0017] During the process of the airflow changing its axial flow direction, the outer layer airflow rotating downward along the inner wall of the acceleration channel and the inner layer airflow rotating upward along the axis of the acceleration channel converge at a position before the outlet of the acceleration channel.

[0018] At the junction, a turbulent airflow is ejected radially outward along the acceleration channel. The turbulent airflow exerts a radially outward disturbance force on the outer airflow. The disturbance force increases the velocity gradient at the junction interface of the outer and inner airflows. After the velocity gradient increases, the dust particles suspended in the outer airflow are thrown away from the junction interface and return to the inner wall of the acceleration channel.

[0019] As a preferred embodiment of the present invention, in step S4, the rotational tangential velocity component of the airflow in the outlet channel gradually decreases during the flow process as follows:

[0020] The airflow in the outlet channel is subjected to flow direction constraints in the first direction and the second direction, respectively, with the first direction and the second direction being perpendicular to each other;

[0021] The flow direction constraint in the first direction attenuates the rotational tangential velocity component of the airflow in the first direction, and the flow direction constraint in the second direction attenuates the rotational tangential velocity component of the airflow in the second direction.

[0022] After being constrained in the first and second directions, the rotational tangential velocity component of the airflow decays to a value that can no longer disturb the agglomerates in the settling space. The airflow with the decayed rotational tangential velocity component is discharged from the end of the outlet channel in a straight flow state.

[0023] A centrifugal separation and purification system for dust generated during ring road reconstruction construction, used to perform any one of the methods described above, including:

[0024] The cyclone separation module is used to receive the dust-laden airflow introduced tangentially and provide a cyclone space. The dust-laden airflow rotates along the inner wall of the cyclone space. During the rotation of the dust-laden airflow, the dust particles inside the airflow move towards the inner wall of the cyclone space under the drive of centrifugal force. The dust particles that move to the inner wall of the cyclone space lose their suspension ability after colliding with the inner wall and slide down to the bottom of the cyclone space. The dust particles that slide down to the bottom of the cyclone space are discharged from the cyclone space through the outlet at the bottom of the cyclone space.

[0025] The acceleration separation module is connected to the bottom of the vortex separation module. Inside the acceleration separation module, an acceleration channel with a flow cross-sectional area that gradually decreases along the airflow direction is formed. The airflow processed by the vortex separation module is discharged from the bottom of the vortex space and enters the acceleration channel. The axial velocity of the airflow in the acceleration channel increases as the flow cross-sectional area decreases. The increase in the axial velocity of the airflow drives the rotation speed of the airflow to increase synchronously. The airflow with the increased rotation speed exerts an enhanced centrifugal force on the residual dust particles carried inside the airflow. Driven by the enhanced centrifugal force, the residual dust particles migrate from the mainstream airflow to the inner wall of the acceleration channel and adhere to the inner wall of the acceleration channel.

[0026] The settling separation module, connected to the outlet of the acceleration separation module, is used to receive the agglomerates detached from the acceleration channel outlet and provide a settling space. After the agglomerates enter the settling space, their movement speed decreases and they settle to the bottom of the settling space under the action of gravity. Dust particles attached to the inner wall of the acceleration channel roll along the inner wall of the acceleration channel towards the outlet of the acceleration channel under the action of the tangential drag force generated by the airflow flowing along the axial direction of the acceleration channel. During the rolling process, the dust particles collide and squeeze with each other. The collision and squeezing cause the dispersed dust particles to agglomerate into agglomerates. Under the combined action of their own gravity and the drag force of the airflow, the agglomerates continue to move along the inner wall of the acceleration channel towards the outlet of the acceleration channel. The agglomerates that move to the outlet of the acceleration channel detach from the acceleration channel and enter the settling space.

[0027] The outlet module, connected to the outlet of the acceleration separation module, is used to discharge the airflow after the separation of residual dust particles from the outlet of the acceleration channel. After being discharged, the airflow changes its flow direction at the outlet of the acceleration channel and flows along the outlet channel formed inside the outlet module. The airflow direction in the outlet channel is isolated from and does not cross the settling direction of the agglomerates in the settling space. During the flow of the airflow in the outlet channel, the rotational tangential velocity component of the airflow in the outlet channel gradually decreases. The airflow after the rotational tangential velocity component decreases is discharged from the end of the outlet channel in a straight flow state.

[0028] As a preferred embodiment of the present invention, the inlet end of the cyclone separation module is connected to a spiral pre-swirl pipe. The spiral pre-swirl pipe is used to apply a spiral pre-swirl operation to the dust-laden airflow before it enters the cyclone separation module. The dust-laden airflow changes from a straight flow to a spiral flow in the spiral pre-swirl pipe and obtains a tangential velocity component along the tangential direction of the spiral path. The spiral radius of the spiral pre-swirl pipe is adjustable. By adjusting the spiral radius of the spiral pre-swirl pipe, the magnitude of the tangential velocity component of the dust-laden airflow is adjusted. When the adjusted dust-laden airflow is introduced into the cyclone separation module, the difference between the tangential velocity component of the dust-laden airflow and the average rotational speed of the airflow in the cyclone separation module does not exceed a preset difference.

[0029] As a preferred embodiment of the present invention, the inner wall of the acceleration channel of the acceleration separation module is provided with compression zones and release zones arranged alternately along the axial direction. When the airflow flows through the compression zone, the static pressure of the airflow increases, and the dust particles in the airflow are pressed against the inner wall surface of the acceleration channel under the action of the increased static pressure. When the airflow flows through the release zone, the static pressure of the airflow decreases, and the dust particles on the inner wall surface of the acceleration channel are peeled off from the inner wall surface under the action of the decreased static pressure. The peeled dust particles are resuspended in the airflow and are pressed against the inner wall surface again when they flow through the compression zone. The dust particles pressed against the inner wall surface again are superimposed on the existing dust layer on the inner wall surface to form a thickened dust layer. The thickened dust layer is peeled off from the inner wall surface as a whole when it flows through the release zone and slides down the inner wall surface.

[0030] As a preferred embodiment of the present invention, a turning space is provided before the outlet of the acceleration separation module, in which the airflow changes from a downward axial flow direction to an upward axial flow direction; the outer layer airflow rotating downward along the inner wall of the acceleration channel and the inner layer airflow rotating upward along the axis of the acceleration channel converge at the entrance of the turning space. An auxiliary airflow inlet is provided on the side wall of the turning space, and the opening direction of the auxiliary airflow inlet is perpendicular to the tangential direction of the inner wall of the turning space. The auxiliary airflow inlet is used to inject auxiliary airflow into the turning space. The auxiliary airflow applies a radially outward disturbance force to the outer layer airflow at the interface of the convergence. The disturbance force increases the velocity gradient at the interface of the outer layer airflow and the inner layer airflow. After the velocity gradient increases, the dust particles suspended in the outer layer airflow are thrown away from the interface of the convergence and return to the inner wall of the acceleration channel.

[0031] As a preferred embodiment of the present invention, a first swirling grid and a second swirling grid are sequentially arranged in the outlet channel along the airflow direction. The extension direction of the bars of the first swirling grid is perpendicular to the extension direction of the bars of the second swirling grid. The first swirling grid is used to apply a flow direction constraint to the airflow in a first direction, so that the rotational tangential velocity component of the airflow in the first direction is attenuated. The second swirling grid is used to apply a flow direction constraint to the airflow in a second direction, so that the rotational tangential velocity component of the airflow in the second direction is attenuated. The first direction and the second direction are perpendicular to each other. After passing through the first swirling grid and the second swirling grid, the rotational tangential velocity component of the airflow is attenuated to a velocity value that cannot disturb the agglomerates in the settling space. The airflow with the attenuated rotational tangential velocity component is discharged from the end of the outlet channel in a straight flow state.

[0032] Compared with the prior art, the beneficial effects of the present invention are:

[0033] 1. This invention uses tangential air intake to create a forced swirling field in the swirling space for the dust-laden airflow. This causes dust particles to be thrown towards the inner wall surface under centrifugal force and slide down the wall surface for discharge, achieving primary separation of dust and airflow. Then, through an acceleration channel with a progressively smaller cross-sectional area, the rotation speed is increased, applying enhanced centrifugal force to the remaining fine dust, achieving secondary deep separation. The synergistic effect of the above two-stage centrifugal separation completes the step-by-step separation of dust particles without external power input. The structure is simple and the operation is stable, overcoming the shortcomings of existing single cyclone separators in terms of insufficient separation capacity for fine dust.

[0034] 2. This invention achieves periodic rises and falls in the static pressure of the airflow by alternately applying compression and release operations along the axial direction within the acceleration channel. The compression operation presses dust particles against the inner wall of the acceleration channel, while the release operation utilizes the expansion stress generated by the sudden pressure drop to peel the dust layer adhering to the wall. After being resuspended, the dust particles are pressed against the wall again in subsequent compression operations, and the layers gradually thicken. In subsequent release operations, the thickened dust layer slides off the wall as a whole because its own weight exceeds the adhesion force of the wall. The above-mentioned cyclic operation of alternating compression and release achieves automatic thickening and overall peeling of dust on the wall, eliminating the need for mechanical scraping devices or vibration mechanisms. This avoids the problems of reduced flow area and decreased separation efficiency caused by dust accumulation on the wall in the prior art.

[0035] 3. This invention involves radially injecting turbulent airflow at a point where the axial flow direction of the airflow changes. This increases the velocity gradient at the interface between the outer layer airflow rotating downwards along the inner wall of the acceleration channel and the inner layer airflow rotating upwards along the axis. Under the influence of the increased velocity gradient, suspended dust particles in the outer layer airflow are thrown away from the interface and return to the inner wall of the acceleration channel. This cuts off the path for unseparated dust particles in the outer layer airflow to be entrained by the rising inner layer airflow. This turbulent injection operation directly targets the secondary dust entrainment defect caused by the oscillation of the vortex core in existing cyclone separators. It blocks the dust back-mixing channel from the perspective of flow field dynamics and significantly reduces the dust concentration in the purified airflow.

[0036] 4. This invention reduces the residual rotational tangential velocity component in the purified airflow step by step by applying flow constraints in two mutually perpendicular directions within the outlet channel, transforming the airflow from a rotating flow to a straight flow state. Furthermore, the outlet channel and the settling space are completely isolated by a partition plate, ensuring that the straight-flowing airflow in the outlet channel does not entrain any agglomerates that have settled in the settling space. This dual guarantee of de-rotation and isolation completely solves the problem of secondary dust re-entrainment of separated dust from both the energy dissipation of the purified airflow itself and the isolation of the flow path, ensuring the cleanliness of the final discharged airflow and allowing the separated dust agglomerates to remain stationary at the bottom of the settling space, facilitating subsequent centralized cleaning. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the overall process of the centrifugal separation and purification method for dust generated during the construction of a ring road in this invention.

[0038] Figure 2 This is a structural framework diagram of the centrifugal separation and purification system for dust generated during the construction of a ring road. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Example 1

[0041] like Figure 1 As shown, this invention provides a method for centrifugal separation and purification of dust generated during ring road reconstruction construction, comprising the following steps:

[0042] S1: The dust-laden airflow generated in the ring road reconstruction construction area is tangentially introduced into a vortex space. The dust-laden airflow rotates along the inner wall of the vortex space. During the rotation, the dust particles inside the dust-laden airflow are subjected to centrifugal force. Driven by the centrifugal force, the dust particles move towards the inner wall of the vortex space. The dust particles that move to the inner wall of the vortex space collide with the inner wall. After the collision, the dust particles lose their suspension ability and slide down along the inner wall. The dust particles that slide to the bottom of the vortex space are discharged from the vortex space through the outlet at the bottom of the vortex space.

[0043] S2: After being processed by S1, the airflow is discharged from the bottom of the vortex space and enters an acceleration channel with a flow cross-sectional area that gradually decreases along the direction of airflow. The axial velocity of the airflow in the acceleration channel increases as the flow cross-sectional area decreases. The increase in the axial velocity of the airflow drives the rotation speed of the airflow to increase synchronously. The airflow with the increased rotation speed exerts an enhanced centrifugal force on the residual dust particles carried inside the airflow. Driven by the enhanced centrifugal force, the residual dust particles migrate outward from the mainstream airflow. The residual dust particles that migrate to the inner wall of the acceleration channel adhere to the inner wall of the acceleration channel.

[0044] S3: Dust particles attached to the inner wall of the acceleration channel are dragged along the wall by the tangential drag force generated by the airflow flowing along the axial direction of the acceleration channel. During the rolling process, the dust particles collide and squeeze with each other. The collision and squeezing cause the dispersed dust particles to agglomerate into agglomerates. Under the combined action of their own gravity and the drag force of the airflow, the agglomerates continue to move along the inner wall of the acceleration channel towards the exit of the acceleration channel. The agglomerates that move to the exit of the acceleration channel leave the acceleration channel and enter a settling space. After entering the settling space, the movement speed of the agglomerates decreases. After the movement speed decreases, the agglomerates settle to the bottom of the settling space under the action of gravity.

[0045] S4: After the residual dust particles in S2 are separated, the airflow is discharged from the outlet of the acceleration channel. After being discharged, the airflow changes its flow direction at the outlet of the acceleration channel and flows along an outlet channel. The airflow direction in the outlet channel is isolated from and does not cross the settling direction of the agglomerates in the settling space. During the flow of the airflow in the outlet channel, the rotational tangential velocity component of the airflow in the outlet channel decreases step by step. The airflow after the rotational tangential velocity component decreases is discharged from the end of the outlet channel in a straight flow state.

[0046] Furthermore, in S1, before the dust-laden airflow is tangentially introduced into the swirling space, a spiral pre-swirl operation is applied to the dust-laden airflow. The spiral pre-swirl operation changes the flow direction of the dust-laden airflow from straight flow to spiral flow. During the spiral flow, the dust-laden airflow obtains a tangential velocity component along the tangential direction of the spiral path.

[0047] The dust-laden airflow with the tangential velocity component is then tangentially introduced into the swirling space. The tangential velocity component of the dust-laden airflow when it is introduced into the swirling space is consistent with the rotation direction of the airflow in the swirling space.

[0048] During the spiral pre-swirl operation, the magnitude of the tangential velocity component of the dust-laden airflow is adjusted by changing the spiral radius of the spiral flow. When the adjusted dust-laden airflow is introduced into the swirling space, the difference between the tangential velocity component of the dust-laden airflow and the average rotational speed of the airflow in the swirling space does not exceed the preset difference.

[0049] Furthermore, in S2, during the process of accelerating and rotating the airflow within the acceleration channel, compression and release operations are sequentially applied to the airflow along the axial direction of the acceleration channel, with the compression and release operations alternating along the axial direction of the acceleration channel.

[0050] The compression operation increases the static pressure of the airflow, and the dust particles in the airflow are forced against the inner wall of the acceleration channel under the action of the increased static pressure.

[0051] The release operation reduces the static pressure of the airflow, accelerating the shedding of dust particles from the inner wall of the channel under the reduced static pressure. The shed dust particles are then resuspended in the airflow and are pressed against the inner wall again during the subsequent compression operation. The dust particles pressed against the inner wall again are superimposed on the existing dust layer on the inner wall, forming a thickened dust layer. The thickened dust layer is then completely detached from the inner wall during the subsequent release operation and slides down the inner wall.

[0052] Furthermore, in S3, as the airflow flows along the axial direction of the acceleration channel toward the outlet of the acceleration channel, when the airflow reaches a position before the outlet of the acceleration channel, the airflow changes its axial flow direction before the outlet of the acceleration channel.

[0053] During the process of the airflow changing its axial flow direction, the outer layer airflow rotating downward along the inner wall of the acceleration channel and the inner layer airflow rotating upward along the axis of the acceleration channel converge at a position before the outlet of the acceleration channel.

[0054] At the junction, a turbulent airflow is ejected radially outward along the acceleration channel. The turbulent airflow exerts a radially outward disturbance force on the outer airflow. The disturbance force increases the velocity gradient at the junction interface of the outer and inner airflows. After the velocity gradient increases, the dust particles suspended in the outer airflow are thrown away from the junction interface and return to the inner wall of the acceleration channel.

[0055] Furthermore, in S4, the rotational tangential velocity component of the airflow in the outlet channel gradually decreases during the flow process as follows:

[0056] The airflow in the outlet channel is subjected to flow direction constraints in the first direction and the second direction, respectively, with the first direction and the second direction being perpendicular to each other;

[0057] The flow direction constraint in the first direction attenuates the rotational tangential velocity component of the airflow in the first direction, and the flow direction constraint in the second direction attenuates the rotational tangential velocity component of the airflow in the second direction.

[0058] After being constrained in the first and second directions, the rotational tangential velocity component of the airflow decays to a value that can no longer disturb the agglomerates in the settling space. The airflow with the decayed rotational tangential velocity component is discharged from the end of the outlet channel in a straight flow state.

[0059] like Figure 2 As shown, the present invention also provides a centrifugal separation and purification system for dust generated during ring road reconstruction construction, used to perform any of the above methods, including:

[0060] The cyclone separation module is used to receive the dust-laden airflow introduced tangentially and provide a cyclone space. The dust-laden airflow rotates along the inner wall of the cyclone space. During the rotation of the dust-laden airflow, the dust particles inside the airflow move towards the inner wall of the cyclone space under the drive of centrifugal force. The dust particles that move to the inner wall of the cyclone space lose their suspension ability after colliding with the inner wall and slide down to the bottom of the cyclone space. The dust particles that slide down to the bottom of the cyclone space are discharged from the cyclone space through the outlet at the bottom of the cyclone space.

[0061] The acceleration separation module is connected to the bottom of the vortex separation module. Inside the acceleration separation module, an acceleration channel with a flow cross-sectional area that gradually decreases along the airflow direction is formed. The airflow processed by the vortex separation module is discharged from the bottom of the vortex space and enters the acceleration channel. The axial velocity of the airflow in the acceleration channel increases as the flow cross-sectional area decreases. The increase in the axial velocity of the airflow drives the rotation speed of the airflow to increase synchronously. The airflow with the increased rotation speed exerts an enhanced centrifugal force on the residual dust particles carried inside the airflow. Driven by the enhanced centrifugal force, the residual dust particles migrate from the mainstream airflow to the inner wall of the acceleration channel and adhere to the inner wall of the acceleration channel.

[0062] The settling separation module, connected to the outlet of the acceleration separation module, is used to receive the agglomerates detached from the acceleration channel outlet and provide a settling space. After the agglomerates enter the settling space, their movement speed decreases and they settle to the bottom of the settling space under the action of gravity. Dust particles attached to the inner wall of the acceleration channel roll along the inner wall of the acceleration channel towards the outlet of the acceleration channel under the action of the tangential drag force generated by the airflow flowing along the axial direction of the acceleration channel. During the rolling process, the dust particles collide and squeeze with each other. The collision and squeezing cause the dispersed dust particles to agglomerate into agglomerates. Under the combined action of their own gravity and the drag force of the airflow, the agglomerates continue to move along the inner wall of the acceleration channel towards the outlet of the acceleration channel. The agglomerates that move to the outlet of the acceleration channel detach from the acceleration channel and enter the settling space.

[0063] The outlet module, connected to the outlet of the acceleration separation module, is used to discharge the airflow after the separation of residual dust particles from the outlet of the acceleration channel. After being discharged, the airflow changes its flow direction at the outlet of the acceleration channel and flows along the outlet channel formed inside the outlet module. The airflow direction in the outlet channel is isolated from and does not cross the settling direction of the agglomerates in the settling space. During the flow of the airflow in the outlet channel, the rotational tangential velocity component of the airflow in the outlet channel gradually decreases. The airflow after the rotational tangential velocity component decreases is discharged from the end of the outlet channel in a straight flow state.

[0064] Furthermore, the inlet end of the cyclone separation module is connected to a spiral pre-swirl pipe. The spiral pre-swirl pipe is used to apply a spiral pre-swirl operation to the dust-laden airflow before it enters the cyclone separation module. The dust-laden airflow changes from a straight flow to a spiral flow in the spiral pre-swirl pipe and obtains a tangential velocity component along the tangential direction of the spiral path. The spiral radius of the spiral pre-swirl pipe is adjustable. By adjusting the spiral radius of the spiral pre-swirl pipe, the magnitude of the tangential velocity component of the dust-laden airflow is adjusted. When the adjusted dust-laden airflow is introduced into the cyclone separation module, the difference between the tangential velocity component of the dust-laden airflow and the average rotational speed of the airflow in the cyclone separation module does not exceed a preset difference.

[0065] Furthermore, the inner wall of the acceleration channel of the acceleration separation module is provided with compression zones and release zones arranged alternately along the axial direction. When the airflow flows through the compression zone, the static pressure of the airflow increases, and the dust particles in the airflow are pressed against the inner wall surface of the acceleration channel under the action of the increased static pressure. When the airflow flows through the release zone, the static pressure of the airflow decreases, and the dust particles on the inner wall surface of the acceleration channel are peeled off from the inner wall surface under the action of the decreased static pressure. The peeled dust particles are resuspended in the airflow and are pressed against the inner wall surface again when they flow through the compression zone. The dust particles pressed against the inner wall surface again are superimposed on the existing dust layer on the inner wall surface to form a thickened dust layer. The thickened dust layer is peeled off from the inner wall surface as a whole when it flows through the release zone and slides down the inner wall surface.

[0066] Furthermore, a turning space is provided before the outlet of the acceleration separation module, where the airflow changes from a downward axial flow direction to an upward axial flow direction. The outer layer airflow rotating downward along the inner wall of the acceleration channel and the inner layer airflow rotating upward along the axis of the acceleration channel converge at the entrance of the turning space. An auxiliary airflow inlet is provided on the side wall of the turning space, and the opening direction of the auxiliary airflow inlet is perpendicular to the tangential direction of the inner wall of the turning space. The auxiliary airflow inlet is used to inject auxiliary airflow into the turning space. The auxiliary airflow exerts a radially outward disturbance force on the outer layer airflow at the interface. The disturbance force increases the velocity gradient at the interface between the outer and inner layer airflows. After the velocity gradient increases, the dust particles suspended in the outer layer airflow are thrown away from the interface and return to the inner wall of the acceleration channel.

[0067] Furthermore, a first swirling grid and a second swirling grid are sequentially arranged along the airflow direction within the outlet channel. The extension direction of the bars of the first swirling grid is perpendicular to the extension direction of the bars of the second swirling grid. The first swirling grid is used to apply a flow constraint in a first direction to the airflow, causing the rotational tangential velocity component of the airflow in the first direction to attenuate. The second swirling grid is used to apply a flow constraint in a second direction to the airflow, causing the rotational tangential velocity component of the airflow in the second direction to attenuate. The first direction and the second direction are perpendicular to each other. After passing through the first swirling grid and the second swirling grid, the rotational tangential velocity component of the airflow is attenuated to a velocity value that cannot disturb the agglomerates in the settling space. The airflow with the attenuated rotational tangential velocity component is discharged from the end of the outlet channel in a straight flow state.

[0068] Example 2

[0069] This embodiment further elaborates on the spiral pre-rotation operation in step S1, based on the above embodiment 1.

[0070] Taking a section of a ring road reconstruction project in a city in southern China as an example, the dust particles in the dust-laden airflow generated during the construction of this section are mainly concentrated in the range of 10μm to 200μm. In response to the particle size distribution characteristics of this type of dust-laden airflow, in step S1, the dust-laden airflow generated in the ring road reconstruction construction area is first introduced into a spiral pre-swirl pipe. The dust-laden airflow moves in a spiral motion along the inner wall of the spiral pre-swirl pipe. The flow direction of the dust-laden airflow changes from straight flow to spiral flow. During the spiral flow, the dust particles are subjected to the initial action of centrifugal force. Dust particles with a diameter greater than 50μm are thrown towards the inner wall of the spiral pre-swirl pipe under the action of centrifugal force and slide down along the inner wall. These large-diameter dust particles are separated and removed before entering the swirling space.

[0071] By adjusting the spiral radius of the spiral pre-swirl pipe, the tangential velocity component of the dust-laden airflow at the outlet of the spiral pre-swirl pipe can be controlled. When the content of fine dust in the dust-laden airflow is high, the spiral radius of the spiral pre-swirl pipe is reduced, the tangential velocity component of the dust-laden airflow increases, and the rotation intensity of the forced swirling field formed after entering the swirling space is correspondingly increased. The forced swirling field's ability to capture fine dust is thus enhanced. After the dust-laden airflow obtains the tangential velocity component in the spiral pre-swirl pipe, it is introduced into the swirling space along the tangential direction of the swirling space. The tangential velocity component of the dust-laden airflow when it enters the swirling space is consistent with the rotation direction of the existing airflow in the swirling space, so as to maintain the flow stability of the forced swirling field in the swirling space.

[0072] During the spiral pre-swirl operation, the tangential velocity component of the dust-laden airflow at the outlet of the spiral pre-swirl pipe is monitored in real time and compared with the average rotational velocity of the airflow in the swirling space. When the difference between the tangential velocity component of the dust-laden airflow and the average rotational velocity of the airflow in the swirling space exceeds the preset difference, the spiral radius of the spiral pre-swirl pipe is adjusted to adjust the tangential velocity component of the dust-laden airflow so that the difference is controlled within the preset difference range. After the dust-laden airflow adjusted by the spiral pre-swirl enters the swirling space, the forced swirling field in the swirling space maintains a stable rotational state, and the uniformity of dust collection on the inner wall of the swirling space is improved, avoiding the decrease in separation efficiency caused by uneven local airflow velocity distribution.

[0073] Taking a section of a ring road reconstruction project in a city in North China as an example, the construction of this section mainly involves road milling. The particle size distribution of dust particles in the generated dust-laden airflow differs from that in southern cities, with fine dust particles ranging from 10μm to 50μm accounting for 20% to 30% of the total dust mass. To address this type of dust-laden airflow, increasing the spiral radius of the spiral pre-swirl pipe reduces the tangential velocity component of the dust-laden airflow. The forced swirling field formed after entering the swirling space has a moderate rotation intensity, ensuring effective separation of fine dust while reducing pressure loss of the airflow in the swirling space and reducing system energy consumption. By adjusting the spiral radius of the spiral pre-swirl pipe as described above, this method can adapt to changes in the particle size distribution of dust-laden airflow under different construction conditions and maintain high separation and purification efficiency.

[0074] Example 3

[0075] Based on Example 1 above, this embodiment further elaborates on the settling process of the aggregates in the settling space in step S3, and the process of the purified airflow being isolated and discharged from the settling space in step S4.

[0076] Taking a section of a ring road reconstruction project in a city as an example, the construction work includes road surface breaking, milling and paving. After the dust-laden airflow generated during construction undergoes swirling separation in step S1 and acceleration separation in step S2, most of the dust particles are separated from the airflow and adhere to the inner wall of the acceleration channel. The dust particles adhering to the inner wall of the acceleration channel roll along the inner wall under the action of tangential drag force. During the rolling process, the dust particles collide and squeeze each other, and the dispersed dust particles gradually agglomerate into agglomerates. The mass of the agglomerates is significantly increased compared to that of individual fine dust particles, and the degree of influence of airflow drag force is significantly reduced.

[0077] The agglomerates roll continuously downwards along the inner wall of the acceleration channel. After reaching the outlet of the acceleration channel, they leave the acceleration channel and enter the settling space. When the agglomerates enter the settling space, they have a velocity component along the tangential direction of the inner wall of the acceleration channel. This velocity component causes the agglomerates to continue rotating along the inner wall of the settling space after entering it. As the agglomerates continue to move in the settling space, friction occurs between the agglomerates and the inner wall of the settling space. The tangential velocity component of the agglomerates gradually decreases. When the tangential velocity component of the agglomerates decreases to an insufficient level to maintain its rotational motion along the wall, the agglomerates settle downwards from the upper part of the settling space under the action of their own gravity, and finally accumulate at the bottom of the settling space.

[0078] During the settling of agglomerates, the purified airflow after the separation of residual dust particles in step S2 is discharged from the outlet of the acceleration channel. The purified airflow changes its flow direction at the outlet of the acceleration channel, changing from downward axial flow to upward axial flow. After changing its flow direction, the purified airflow flows along the outlet channel, which is located above the settling space. The outlet channel and the settling space are separated by a partition plate. The partition plate completely separates the airflow path in the outlet channel from the settling path of the agglomerates in the settling space. The purified airflow flowing in the outlet channel will not cause airflow disturbance to the agglomerates settling in the settling space.

[0079] A first swirling grid and a second swirling grid are sequentially arranged along the airflow direction in the outlet channel. When the purified airflow passes through the first swirling grid, the grid bars of the first swirling grid apply a flow direction constraint in the first direction to the purified airflow, and the rotational tangential velocity component of the purified airflow in the first direction is weakened. When the purified airflow continues to flow and passes through the second swirling grid, the grid bars of the second swirling grid apply a flow direction constraint in the second direction to the purified airflow, and the rotational tangential velocity component of the purified airflow in the second direction is weakened. The first direction and the second direction are perpendicular to each other. After being constrained by two orthogonal directions, the residual rotational tangential velocity component of the purified airflow is reduced to a velocity value that cannot disturb the agglomerates in the settling space.

[0080] After being processed by the first and second swirling grids, the purified airflow changes from a rotating flow to a straight flow. The straight-flowing purified airflow is discharged along the end of the outlet channel. Since the tangential velocity component of the purified airflow has been largely eliminated, and the outlet channel and the settling space are separated by a partition plate, the purified airflow discharged from the outlet channel will not have a suction effect on the agglomerates accumulated in the settling space. The agglomerates at the bottom of the settling space remain stationary and can be discharged from the bottom of the settling space periodically to complete the final collection of dust. Through the above-mentioned isolation design between the outlet channel and the settling space, and the de-swirl treatment of the purified airflow by the swirling grid in the outlet channel, the purified airflow and the separated dust agglomerates are completely separated, avoiding secondary dust re-entrainment after separation.

[0081] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A centrifugal separation and purification method for dust generated during ring road reconstruction construction, characterized in that, Includes the following steps: S1: The dust-laden airflow generated in the ring road reconstruction construction area is tangentially introduced into a vortex space. The dust-laden airflow rotates along the inner wall of the vortex space. During the rotation, the dust particles inside the dust-laden airflow are subjected to centrifugal force. Driven by the centrifugal force, the dust particles move towards the inner wall of the vortex space. The dust particles that move to the inner wall of the vortex space collide with the inner wall. After the collision, the dust particles lose their suspension ability and slide down along the inner wall. The dust particles that slide to the bottom of the vortex space are discharged from the vortex space through the outlet at the bottom of the vortex space. S2: After being processed by S1, the airflow is discharged from the bottom of the vortex space and enters an acceleration channel with a flow cross-sectional area that gradually decreases along the direction of airflow. The axial velocity of the airflow in the acceleration channel increases as the flow cross-sectional area decreases. The increase in the axial velocity of the airflow drives the rotation speed of the airflow to increase synchronously. The airflow with the increased rotation speed exerts an enhanced centrifugal force on the residual dust particles carried inside the airflow. Driven by the enhanced centrifugal force, the residual dust particles migrate outward from the mainstream airflow. The residual dust particles that migrate to the inner wall of the acceleration channel adhere to the inner wall of the acceleration channel. S3: Dust particles attached to the inner wall of the acceleration channel are dragged along the wall by the tangential drag force generated by the airflow flowing along the axial direction of the acceleration channel. During the rolling process, the dust particles collide and squeeze with each other. The collision and squeezing cause the dispersed dust particles to agglomerate into agglomerates. Under the combined action of their own gravity and the drag force of the airflow, the agglomerates continue to move along the inner wall of the acceleration channel towards the exit of the acceleration channel. The agglomerates that move to the exit of the acceleration channel leave the acceleration channel and enter a settling space. After entering the settling space, the movement speed of the agglomerates decreases. After the movement speed decreases, the agglomerates settle to the bottom of the settling space under the action of gravity. S4: After the residual dust particles in S2 are separated, the airflow is discharged from the outlet of the acceleration channel. After being discharged, the airflow changes its flow direction at the outlet of the acceleration channel and flows along an outlet channel. The airflow direction in the outlet channel is isolated from and does not cross the settling direction of the agglomerates in the settling space. During the flow of the airflow in the outlet channel, the rotational tangential velocity component of the airflow in the outlet channel decreases step by step. The airflow after the rotational tangential velocity component decreases is discharged from the end of the outlet channel in a straight flow state.

2. The method according to claim 1, characterized in that, In S1, before the dust-laden airflow is tangentially introduced into the swirling space, a spiral pre-swirl operation is applied to the dust-laden airflow. The spiral pre-swirl operation changes the flow direction of the dust-laden airflow from straight flow to spiral flow. During the spiral flow, the dust-laden airflow obtains a tangential velocity component along the tangential direction of the spiral path. The dust-laden airflow with the tangential velocity component is then introduced tangentially into the swirling space. The tangential velocity component of the dust-laden airflow when it is introduced into the swirling space is consistent with the rotation direction of the airflow in the swirling space. During the spiral pre-swirl operation, the magnitude of the tangential velocity component of the dust-laden airflow is adjusted by changing the spiral radius of the spiral flow. When the adjusted dust-laden airflow is introduced into the swirling space, the difference between the tangential velocity component of the dust-laden airflow and the average rotational speed of the airflow in the swirling space does not exceed the preset difference.

3. The method according to claim 1, characterized in that, In S2, during the process of accelerating and rotating the airflow in the acceleration channel, compression and release operations are sequentially applied to the airflow along the axial direction of the acceleration channel, with the compression and release operations alternating along the axial direction of the acceleration channel. The compression operation increases the static pressure of the airflow, and the dust particles in the airflow are forced against the inner wall of the acceleration channel under the action of the increased static pressure. The release operation reduces the static pressure of the airflow, accelerating the shedding of dust particles from the inner wall of the channel under the reduced static pressure. The shed dust particles are then resuspended in the airflow and are pressed against the inner wall again during the subsequent compression operation. The dust particles pressed against the inner wall again are superimposed on the existing dust layer on the inner wall, forming a thickened dust layer. The thickened dust layer is then completely detached from the inner wall during the subsequent release operation and slides down the inner wall.

4. The method according to claim 1, characterized in that, In S3, as the airflow flows along the axial direction of the acceleration channel toward the outlet of the acceleration channel, when the airflow reaches a position before the outlet of the acceleration channel, the airflow changes its axial flow direction before the outlet of the acceleration channel. During the process of the airflow changing its axial flow direction, the outer layer airflow rotating downward along the inner wall of the acceleration channel and the inner layer airflow rotating upward along the axis of the acceleration channel converge at a position before the outlet of the acceleration channel. At the junction, a turbulent airflow is ejected radially outward along the acceleration channel. The turbulent airflow exerts a radially outward disturbance force on the outer airflow. The disturbance force increases the velocity gradient at the junction interface of the outer and inner airflows. After the velocity gradient increases, the dust particles suspended in the outer airflow are thrown away from the junction interface and return to the inner wall of the acceleration channel.

5. The method according to claim 1, characterized in that, In step S4, the process by which the rotational tangential velocity component of the airflow in the outlet channel gradually decreases during the flow is as follows: The airflow in the outlet channel is subjected to flow direction constraints in the first direction and the second direction, respectively, with the first direction and the second direction being perpendicular to each other; The flow direction constraint in the first direction attenuates the rotational tangential velocity component of the airflow in the first direction, and the flow direction constraint in the second direction attenuates the rotational tangential velocity component of the airflow in the second direction. After being constrained in the first and second directions, the rotational tangential velocity component of the airflow decays to a value that can no longer disturb the agglomerates in the settling space. The airflow with the decayed rotational tangential velocity component is discharged from the end of the outlet channel in a straight flow state.

6. A centrifugal separation and purification system for dust generated during ring road reconstruction construction, used to execute the method according to any one of claims 1-5, characterized in that, include: The cyclone separation module is used to receive the dust-laden airflow introduced tangentially and provide a cyclone space. The dust-laden airflow rotates along the inner wall of the cyclone space. During the rotation of the dust-laden airflow, the dust particles inside the airflow move towards the inner wall of the cyclone space under the drive of centrifugal force. The dust particles that move to the inner wall of the cyclone space lose their suspension ability after colliding with the inner wall and slide down to the bottom of the cyclone space. The dust particles that slide down to the bottom of the cyclone space are discharged from the cyclone space through the outlet at the bottom of the cyclone space. The acceleration separation module is connected to the bottom of the vortex separation module. Inside the acceleration separation module, an acceleration channel with a flow cross-sectional area that gradually decreases along the airflow direction is formed. The airflow processed by the vortex separation module is discharged from the bottom of the vortex space and enters the acceleration channel. The axial velocity of the airflow in the acceleration channel increases as the flow cross-sectional area decreases. The increase in the axial velocity of the airflow drives the rotation speed of the airflow to increase synchronously. The airflow with the increased rotation speed exerts an enhanced centrifugal force on the residual dust particles carried inside the airflow. Driven by the enhanced centrifugal force, the residual dust particles migrate from the mainstream airflow to the inner wall of the acceleration channel and adhere to the inner wall of the acceleration channel. The settling separation module is connected to the outlet of the acceleration separation module. It is used to receive the agglomerates that detach from the outlet of the acceleration channel and provide a settling space. After the agglomerates enter the settling space, their movement speed decreases and they settle to the bottom of the settling space under the action of gravity. Dust particles adhering to the inner wall of the acceleration channel roll along the inner wall of the acceleration channel toward the outlet direction under the tangential drag force generated by the airflow flowing along the axial direction of the acceleration channel. During the rolling process, the dust particles collide and squeeze with each other. The collision and squeezing cause the dispersed dust particles to agglomerate into agglomerates. Under the combined action of their own gravity and the drag force of the airflow, the agglomerates continue to move along the inner wall of the acceleration channel toward the outlet direction. The agglomerates that move to the outlet of the acceleration channel detach from the acceleration channel and enter the settling space. The outlet module, connected to the outlet of the acceleration separation module, is used to discharge the airflow after the separation of residual dust particles from the outlet of the acceleration channel. After being discharged, the airflow changes its flow direction at the outlet of the acceleration channel and flows along the outlet channel formed inside the outlet module. The airflow direction in the outlet channel is isolated from and does not cross the settling direction of the agglomerates in the settling space. During the flow of the airflow in the outlet channel, the rotational tangential velocity component of the airflow in the outlet channel gradually decreases. The airflow after the rotational tangential velocity component decreases is discharged from the end of the outlet channel in a straight flow state.

7. The system according to claim 6, characterized in that, The inlet end of the cyclone separation module is connected to a spiral pre-swirl pipe. The spiral pre-swirl pipe is used to apply a spiral pre-swirl operation to the dust-laden airflow before it enters the cyclone separation module. The dust-laden airflow changes from a straight flow to a spiral flow in the spiral pre-swirl pipe and obtains a tangential velocity component along the tangential direction of the spiral path. The spiral radius of the spiral pre-swirl pipe is adjustable. By adjusting the spiral radius of the spiral pre-swirl pipe, the magnitude of the tangential velocity component of the dust-laden airflow is adjusted. When the adjusted dust-laden airflow is introduced into the cyclone separation module, the difference between the tangential velocity component of the dust-laden airflow and the average rotational speed of the airflow in the cyclone separation module does not exceed a preset difference.

8. The system according to claim 6, characterized in that, The acceleration channel of the acceleration separation module has compression and release zones arranged alternately along the axial direction on its inner wall. When the airflow passes through the compression zone, the static pressure of the airflow increases, and the dust particles in the airflow are pressed against the inner wall of the acceleration channel under the action of the increased static pressure. When the airflow passes through the release zone, the static pressure of the airflow decreases, and the dust particles on the inner wall of the acceleration channel are peeled off from the inner wall under the action of the decreased static pressure. The peeled dust particles are resuspended in the airflow and are pressed against the inner wall again when they subsequently pass through the compression zone. The dust particles pressed against the inner wall again are superimposed on the existing dust layer on the inner wall and form a thickened dust layer. The thickened dust layer is peeled off from the inner wall as a whole when it subsequently passes through the release zone and slides down the inner wall.

9. The system according to claim 6, characterized in that, A turning space is provided before the outlet of the acceleration separation module. In the turning space, the airflow changes from a downward axial flow direction to an upward axial flow direction. The outer layer airflow rotating downward along the inner wall of the acceleration channel and the inner layer airflow rotating upward along the axis of the acceleration channel converge at the entrance of the turning space. An auxiliary airflow inlet is provided on the side wall of the turning space. The opening direction of the auxiliary airflow inlet is perpendicular to the tangent direction of the inner wall of the turning space. The auxiliary airflow inlet is used to inject auxiliary airflow into the turning space. The auxiliary airflow applies a radially outward disturbance force to the outer layer airflow at the interface. The disturbance force increases the velocity gradient at the interface of the outer and inner layer airflows. After the velocity gradient increases, the dust particles suspended in the outer layer airflow are thrown away from the interface and return to the inner wall of the acceleration channel.

10. The system according to claim 6, characterized in that, The outlet channel is provided with a first swirl-blocking grid and a second swirl-blocking grid in sequence along the airflow direction. The extension direction of the bars of the first swirl-blocking grid is perpendicular to the extension direction of the bars of the second swirl-blocking grid. The first swirl-blocking grid is used to apply a flow direction constraint to the airflow in a first direction, so that the rotational tangential velocity component of the airflow in the first direction is attenuated. The second swirl-blocking grid is used to apply a flow direction constraint to the airflow in a second direction, so that the rotational tangential velocity component of the airflow in the second direction is attenuated. The first direction and the second direction are perpendicular to each other. After passing through the first swirl-blocking grid and the second swirl-blocking grid, the rotational tangential velocity component of the airflow is attenuated to a velocity value that can no longer disturb the agglomerates in the settling space. The airflow with the attenuated rotational tangential velocity component is discharged from the end of the outlet channel in a straight flow state.

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