A protection device for sludge multi-stage screw conveyor

Abstract

This utility model belongs to the field of wastewater treatment technology, specifically disclosing a protective device for a multi-stage sludge screw conveyor. It includes a movable cover plate for sealing the screw conveyor and a screw protection unit linked to the movable cover plate. A transmission component is connected to the end of the movable cover plate. The screw protection unit contains an elastic element and a normally closed contact. A locking element linked to the transmission component is also mounted on the screw protection unit. The normally closed contact is connected in series in the electrical control circuit of the screw conveyor's drive motor. When sludge leakage from the screw conveyor generates thrust that lifts the movable cover plate, the movable cover plate triggers the locking element to unlock via the transmission component. This causes the elastic element to drive the normally closed contact to open, thus cutting off the electrical control circuit and stopping the drive motor. This utility model can prevent large-scale sludge leakage from the screw conveyor and allows for timely shutdown in case of screw conveyor malfunction.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment technology, specifically to a protective device for a multi-stage screw conveyor for sludge. Background Technology

[0002] In the advanced sludge treatment stage of the wastewater treatment industry, plate and frame filter presses, with their superior solid-liquid separation performance, have become one of the core devices for achieving high-quality sludge filtration. By applying pressure, this equipment can efficiently separate water from the sludge, producing a highly transparent filtrate that effectively reduces the burden on subsequent water treatment. It also ensures the separated solids reach an ideal degree of dryness, significantly improving sludge reduction and achieving an extremely high solids recovery rate. This lays a solid foundation for the resource utilization of sludge (such as in the production of building aggregates and cover soil), leading to its widespread application in the industry.

[0003] However, the efficient operation of plate and frame filter presses highly depends on the stability of the upstream sludge transport system. The multi-stage screw conveyor, as a key transport device connecting the sludge storage unit and the filter press, directly affects the continuity and safety of the overall processing flow. In actual operation, when the sludge to be treated is substandard, it easily accumulates at the joints of the multi-stage screw conveyor, leading to serious malfunctions. Due to the poor flowability and high resistance of substandard sludge, localized high pressure is generated at the joints during the pushing process by the screw blades, which can then rupture the screw conveyor's cover plate. This malfunction not only causes a large amount of sludge leakage, polluting the surrounding working environment and increasing the workload of on-site cleanup, but also directly damages the equipment, such as deformation of the screw blades and damage to the bolt holes of the screw cover plate, preventing the cover plate from sealing and securing properly.

[0004] The chain reaction triggered by the above problems has further exacerbated the pain points in production and operation: on the one hand, the maintenance after equipment failure requires the replacement of cover plates, repair of bolt holes, and even replacement of spiral components, resulting in a significant increase in subsequent maintenance costs; on the other hand, the cleaning of leaked sludge, the dismantling and maintenance of equipment all require a large amount of manual operation, which not only occupies valuable production time and reduces processing efficiency, but also increases the safety hazards for operators (such as contact injury, inhalation risk, etc.) because the sludge may contain harmful pollutants, which seriously restricts the stable and efficient operation of the sewage treatment system. Utility Model Content

[0005] This utility model provides a protective device for a multi-stage screw conveyor for sludge, which aims to prevent a large amount of sludge leakage from the screw conveyor and to stop the machine in time when the screw conveyor malfunctions.

[0006] This utility model is achieved through the following technical solution: a protective device for a multi-stage screw conveyor for sludge, comprising a movable cover plate for sealing the screw conveyor and a screw protection unit linked with the movable cover plate;

[0007] The movable cover plate is connected to a transmission component at its end. The spiral protection unit is equipped with an elastic component and a normally closed contact. The spiral protection unit is also equipped with a locking component that is linked to the transmission component. The normally closed contact is connected in series in the electrical control circuit of the drive motor of the spiral conveyor.

[0008] When sludge leakage inside the screw conveyor generates thrust that lifts the movable cover plate, the movable cover plate triggers the locking element to unlock via a transmission component, causing the elastic element to drive the normally closed contact to open, thereby cutting off the electrical control circuit to stop the drive motor from operating.

[0009] Compared with existing technologies, this solution has the following advantages and beneficial effects:

[0010] In this solution, when sludge leaks due to excessive moisture content or high viscosity, creating localized high pressure within the screw conveyor, the thrust generated by the leaking sludge directly lifts the movable cover. The movable cover then triggers the locking mechanism of the screw protection unit via an end transmission component to unlock. After unlocking, the elastic element quickly drives the normally closed contact to open, directly cutting off the electrical control circuit of the drive motor and immediately stopping the screw conveyor. This prevents a large-scale sludge leak and ensures timely shutdown in case of a screw conveyor malfunction. This process can quickly terminate sludge transport in the early stages of leakage, preventing continuous leakage of large amounts of sludge and contamination of the working environment. It also prevents excessive scouring or crushing damage to core components such as the screw blades and screw conveyor housing caused by leaking sludge, significantly reducing the probability of mechanical failures caused by sludge leakage.

[0011] In addition, in this solution, the movable cover is lifted when sludge leaks. The transmission component at the end of the movable cover is pulled open, which unlocks the locking component. Under the action of the elastic component, the normally closed contact is disconnected and the machine stops, thus preventing the end of the cover from bursting and damaging the entire spiral cover.

[0012] Furthermore, the electrical control circuit is also connected to an alarm, which is activated and sounds an alarm when the normally closed contact is opened.

[0013] Beneficial Effects: After a screw conveyor stops, maintenance personnel often need to conduct routine inspections to discover the fault, resulting in a delay in fault detection. However, the alarm's linkage design proactively transmits fault signals to on-site personnel the instant the conveyor stops. Whether it's operators in the workshop or monitoring personnel in the control room, they can immediately become aware of the screw conveyor leak through visual signals such as sound (buzzer) and light (red warning light), eliminating the need for manual inspections. This design significantly shortens the time lag after a fault occurs, creating conditions for maintenance personnel to quickly reach the fault site and carry out cleaning and repair work. It effectively reduces the impact of the fault on subsequent sludge treatment processes and minimizes the decrease in work efficiency caused by downtime.

[0014] Furthermore, it also includes a breakable connector that connects the movable cover plate to the screw conveyor body, the breakable connector breaking when the movable cover plate is lifted.

[0015] Beneficial effects: In traditional connection methods, if rigid connectors such as metal bolts are used, when the movable cover is pushed up by the force of sludge leakage, huge stresses will be generated between the bolts, the bolt holes of the cover, and the connection structure of the conveyor body. This stress can easily lead to deformation and cracking of the bolt holes, and even breakage of the connecting lugs of the conveyor body. Such damage is a permanent structural failure, and repair requires complex processing such as cutting, welding, and re-drilling of the cover or body. Not only is the repair difficult and time-consuming, but insufficient processing precision may also affect the subsequent sealing performance. In severe cases, the entire cover or body may need to be replaced, significantly increasing equipment costs.

[0016] The design of the easily breakable connector precisely matches the fracture strength, prioritizing fracture when the thrust reaches the trigger threshold, actively releasing stress and protecting the connection structure between the movable cover and the conveyor body from impact. After fracture, only the low-cost easily breakable connector needs to be replaced to restore equipment assembly, effectively avoiding permanent damage to core components caused by stress concentration and significantly reducing the risk of equipment scrapping.

[0017] Furthermore, the easily breakable connector is a plastic bolt, and the breaking strength of the plastic bolt is less than the withstand strength of the connection between the movable cover plate and the screw conveyor body.

[0018] Beneficial Effects: In this solution, when the sludge leakage generates thrust that lifts the movable cover, the thrust first acts on the plastic bolts. Because plastic bolts have lower breaking strength, they will break first when the thrust reaches their breaking threshold. Meanwhile, core connection parts such as the bolt holes of the movable cover and the connecting lugs of the conveyor body, due to their higher strength, can completely avoid stress impact. Compared to easily broken connectors made of other materials, the breaking strength of plastic bolts is more easily controlled through material selection (such as engineering plastics of different strength grades like polyethylene and polypropylene). This strictly ensures a protection logic of bolts breaking first and components remaining undamaged, completely avoiding the problem of components failing first and bolts failing later in traditional rigid connections, and minimizing the risk of permanent damage to core connection parts.

[0019] Furthermore, the spiral protection unit also includes a housing, in which the elastic element, normally closed contact and locking element are all encapsulated. The housing is provided with a guide hole for the locking element to be inserted or withdrawn.

[0020] Beneficial effects: During the multi-stage screw conveying of sludge, there are often leaks of sludge, water vapor, dust and corrosive gases on site. If the core components are exposed, problems such as sludge adhesion causing elastic parts to jam (such as spring corrosion and obstructed expansion and contraction), poor contact of normally closed contacts (sludge covering causing short circuits or open circuits), and wear of locking parts (dust entering and causing a decrease in locking accuracy) may occur.

[0021] The outer casing effectively prevents external contaminants from entering, ensuring smooth expansion and contraction of the elastic element, stable electrical connection of the normally closed contacts, and precise locking and unlocking of the locking element. This prevents core components from being damaged by external contamination or accidental collisions, extends the service life of the spiral protection unit, and reduces the risk of protection mechanism failure due to component malfunction. The guide hole in this solution provides the necessary channel for the movement of the locking element.

[0022] Furthermore, the transmission component is a pull rope, one end of which is fixed to the end of the movable cover plate, and the other end is connected to the locking component of the spiral protection unit; when the movable cover plate is lifted, the pull rope pulls the locking component to disengage from the locked state.

[0023] Beneficial effects: When sludge leakage generates thrust that lifts the movable cover, the displacement at the end of the movable cover is converted into a pulling force on the locking component through the pull rope. The flexible material of the pull rope allows it to adapt to the spatial layout between the movable cover and the locking component (such as the presence of a certain angle or non-linear path), avoiding the interruption of force transmission due to the strict limitation of the installation position by rigid transmission components (such as metal rods).

[0024] Meanwhile, the pull rope can be adjusted to precisely match the distance between the two, ensuring that the pulling force can be effectively applied to the locking component as soon as the movable cover is lifted, pushing the locking component out of the locked state.

[0025] Furthermore, the spiral protection unit also includes a baffle located inside the housing, the elastic element is a spring, the locking element is a safety bolt, one end of the spring is connected to the housing, the other end of the spring is connected to the baffle, and the baffle is connected to the normally closed contact;

[0026] When the safety bolt is locked, it contacts the baffle and compresses the spring to close the normally closed contact. When the safety bolt is unlocked, the spring rebounds and pushes the baffle to reset, thus opening the normally closed contact.

[0027] Beneficial effects: When the safety bolt is locked, it directly contacts the baffle and applies pressure, compressing the spring. The compressed spring, through the baffle, exerts continuous and stable pressure on the normally closed contacts, ensuring a tight fit and maintaining electrical control circuit continuity, allowing the screw conveyor drive motor to operate normally. When the safety bolt unlocks (pulled away from the baffle by the pull rope), the spring's compression is released, causing it to quickly rebound and push the baffle back to its original position. The baffle's reset action directly acts on the normally closed contacts, separating them from the contacted state and achieving precise disconnection of the electrical control circuit. Compared to designs where the spring directly acts on the normally closed contacts, the baffle evenly distributes the spring force to the normally closed contacts, preventing uneven spring force that could lead to poor contact or damage. This ensures reliable implementation of the locking and unlocking logic, providing stable electrical triggering conditions for emergency motor shutdown.

[0028] Furthermore, two springs are provided, and the two springs are respectively connected to the upper and lower parts of the baffle.

[0029] Beneficial effects: When the safety bolt is locked, the two springs are compressed synchronously from the upper and lower ends of the baffle. The pressure transmitted to the normally closed contact through the baffle is evenly distributed in the upper and lower areas of the contact, ensuring that the normally closed contact fits tightly as a whole. This prevents the contact from tilting or causing poor contact due to excessive pressure on one side, thereby avoiding problems such as intermittent power outages or excessive contact resistance in the electrical control circuit.

[0030] When the safety bolt is unlocked, the two springs rebound synchronously from the top and bottom, pushing the baffle to return to its original position smoothly along a straight line. This causes the normally closed contacts to separate synchronously in the upper and lower areas, preventing the "partial disconnection" state where one end of the contact disconnects first while the other end remains in contact due to the baffle tilting. This ensures that the electrical control circuit is completely cut off instantly, providing a more precise triggering guarantee for the emergency stop of the screw conveyor drive motor and avoiding motor shutdown delays or malfunctions caused by incomplete contact switching.

[0031] Furthermore, the movable cover plate is hinged to the cover plate on the screw conveyor.

[0032] Beneficial effects: When sludge leakage generates thrust on the movable cover, the hinge point becomes the rotation center of the movable cover, ensuring that the cover can only be flipped upwards around the hinge point. This prevents the movable cover from shifting, tilting, or jamming due to the lack of a fixed support point. For example, if a non-hinged free connection is used, the movable cover may shift to the side due to uneven thrust, failing to effectively lift the end pull rope. The hinged design ensures that the movable cover can be lifted upwards along a preset flipping trajectory regardless of the direction of the leakage thrust. This precisely pulls the end pull rope, triggering the locking mechanism of the spiral protection unit to unlock, ensuring the continuous triggering of the leakage → lifting → shutdown protection logic and preventing the protection mechanism from failing due to deviations in the movable cover's movement.

[0033] Furthermore, the electrical control circuit includes a main power switch, a main circuit, and a control circuit; the main circuit is connected in series with the main power switch, the main contact of the contactor, and the drive motor; the control circuit is connected in series with the main power switch, the fuse, the stop button, the start button, the contactor coil, and the normally closed contact, and the contactor coil is connected in parallel with a contactor auxiliary normally open contact to achieve self-locking.

[0034] Beneficial effects: The main circuit, consisting of the main power switch, the main contacts of the contactor, and the drive motor connected in series, is specifically responsible for providing high-power power to the drive motor of the screw conveyor, meeting the power requirements of the motor operation; the main contacts of the contactor have the characteristic of withstanding large currents, which can avoid contact burnout caused by current overload and ensure the stability of power transmission.

[0035] The control circuit connects the main power switch, fuse, stop button, start button, contactor coil, and normally closed contacts in series. The main circuit's start and stop can be indirectly controlled by switching the contactor coil on and off using only a low-current signal. This separate design avoids high current interference from the main circuit's logic signals in the control circuit, and prevents control circuit faults (such as short circuits) from affecting the main circuit's safety, significantly reducing the overall electrical system failure risk and ensuring safe equipment operation. Attached Figure Description

[0036] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0037] Figure 1 This is a schematic diagram of the structure of a protective device for a multi-stage screw conveyor for sludge, installed on the multi-stage screw conveyor according to the present invention;

[0038] Figure 2 for Figure 1 A magnified view of a section at point A in the middle;

[0039] Figure 3This is a partial structural schematic diagram of a protective device for a multi-stage screw conveyor for sludge according to the present invention.

[0040] The attached diagram shows the markings and corresponding component names:

[0041] 1. Movable cover plate; 2. Plastic bolts; 3. Pull rope;

[0042] 4. Spiral protection unit; 41. Safety bolt; 42. Housing; 43. Baffle; 44. Wire; 45. Contact; 46. Spring.

[0043] 5. Screw conveyor; 6. Hinges. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this utility model are only used to explain this utility model and are not intended to limit this utility model.

[0045] like Figures 1-2 As shown, this embodiment provides a protective device for a multi-stage screw conveyor for sludge, including a movable cover plate 1 for sealing the screw conveyor 5 and a screw protection unit 4 linked with the movable cover plate 1. In this embodiment, the movable cover plate 1 is hinged to the cover plate on the screw conveyor 5. Specifically, the protective device in this embodiment is installed at the joint of the multi-stage screw conveyor 5, and a section is cut off at one end of the original cover plate of the screw conveyor 5 so that one end of the movable cover plate 1 is hinged to the original cover plate of the screw conveyor 5 through a hinge 6.

[0046] In this embodiment, the end of the movable cover plate 1 is connected to a transmission component, the spiral protection unit 4 is provided with an elastic component and a normally closed contact 45, and the spiral protection unit 4 is equipped with a locking component that is linked to the transmission component. The normally closed contact 45 is connected in series in the electrical control circuit of the drive motor of the spiral conveyor 5.

[0047] When the sludge leakage inside the screw conveyor 5 generates thrust that lifts the movable cover plate 1, the movable cover plate 1 triggers the locking element to unlock through the transmission component, causing the elastic element to drive the normally closed contact 45 to open, thus cutting off the electrical control circuit to stop the drive motor from running.

[0048] In one embodiment, such as Figure 2 As shown, a protective device for a multi-stage screw conveyor for sludge in this embodiment also includes a breakable connector that connects the movable cover plate 1 to the screw conveyor body 5. The breakable connector breaks when the movable cover plate 1 is lifted.

[0049] In this embodiment, the easily breakable connecting component is the plastic bolt 2. The breaking strength of the plastic bolt 2 is less than the withstand strength of the connection between the movable cover plate 1 and the screw conveyor 5 body. The plastic bolt 2 is designed to ensure that the movable cover plate 1 can be cut off in time when it is pushed up by the sludge, without damaging the bolt holes of the movable cover plate 1.

[0050] In one embodiment, such as Figure 2 As shown, the spiral protection unit 4 also includes a housing 42, in which the elastic element, normally closed contact 45, and locking element are all encapsulated. The housing 42 is provided with a guide hole for the locking element to be inserted or withdrawn. The housing 42 is fixed to the outside of the spiral conveyor 5 by bolts.

[0051] In one embodiment, such as Figure 2 As shown, the transmission component is a pull rope 3. One end of the pull rope 3 is fixed to the end of the movable cover plate 1, and the other end is connected to the locking component of the spiral protection unit 4. In this embodiment, through holes for the pull rope 3 to pass through are provided on both the movable cover plate 1 and the locking component. The pull rope 3 is fixed to the movable cover plate 1 and the locking component by knotting, bonding and other fixing methods. When the movable cover plate 1 is lifted by sludge, the movable cover plate 1 drives the pull rope 3 to pull the locking component out of the locked state, thereby causing the normally closed contact 45 to open.

[0052] In one embodiment, combined Figure 2 and Figure 3 As shown, in this embodiment, the spiral protection unit 4 also includes a baffle 43, which is located inside the housing 42. In this embodiment, the elastic element is a spring 46 and the locking element is a safety bolt 41. One end of the spring 46 is connected to the housing 42, and the other end of the spring 46 is connected to the baffle 43. The baffle 43 is connected to the normally closed contact 45. In this embodiment, both ends of the spring 46 are welded to the housing 42 and the baffle 43 respectively, or connected in other ways. The baffle 43 is welded to the normally closed contact 45, or connected in other ways.

[0053] When the safety bolt 41 is locked, it contacts the baffle 43 and compresses the spring 46, thus closing the normally closed contact 45. When the safety bolt 41 is unlocked, the spring 46 rebounds and pushes the baffle 43 back to its original position, thus opening the normally closed contact 45. When the safety bolt 41 is inserted into the housing 42 and contacts the baffle 43, it exerts a squeezing force on the baffle 43, which compresses the spring 46. At this time, the normally closed contact 45 is closed. When sludge leaks from the screw conveyor 5 and squeezes the movable cover 1, it will exert an upward pushing force on the movable cover 1, causing the pull rope 3 to pull open the safety bolt 41, moving the safety bolt 41 away from the baffle 43. Under the action of the spring 46, the baffle 43 will return to its original position to the right. During the return process of the baffle 43, the normally closed contact 45 will be opened, thereby stopping the screw conveyor 5.

[0054] When sludge leaks and pushes up the end of the cover plate, the pull rope 3 will pull open the safety bolt 41 in the spiral protection unit 4. After the safety bolt 41 is pulled open, the spring 46 will pop open the normally closed contact 45. The normally closed contact 45 is connected to the electrical system, which will de-energize the drive motor and stop the spiral conveyor 5 from working, so that the sludge will not continue to leak out.

[0055] In one embodiment, such as Figure 3 As shown, in this embodiment, two springs 46 are provided, and the two springs 46 are respectively connected to the upper and lower parts of the baffle 43.

[0056] In one embodiment, the electrical control circuit includes a main power switch, a main circuit, and a control circuit; the main circuit is connected in series with the main power switch, the main contact 45 of the contactor, and the drive motor; the control circuit is connected in series with the main power switch, the fuse, the stop button, the start button, the contactor coil, and the normally closed contact 45, and the contactor coil is connected in parallel with the contactor auxiliary normally open contact 45 to achieve self-locking.

[0057] like Figure 3 As shown, the power output terminal of the electrical system (such as the main contact 45 of the contactor) is directly connected to the drive motor of the screw conveyor 5 through the wire 44, forming the main circuit for the operation of the equipment and providing power to the screw conveyor 5. The on / off state of the main circuit directly determines the start and stop state of the screw conveyor 5.

[0058] The normally closed contact 45 is connected in series in the control circuit of the electrical system via wire 44, and the control circuit is also connected to the contactor coil of the main circuit.

[0059] After the operator presses the start button, the contactor coil is energized, the main contact 45 of the contactor closes to make the motor run, and the auxiliary normally open contact 45 of the contactor closes simultaneously. After the start button is released, the current can continuously supply power to the coil through the path of "contactor auxiliary normally open contact 45 → contactor coil → normally closed contact 45", so that the equipment can be maintained without continuously pressing the start button, completely freeing the operator's hands and reducing the intensity of operation.

[0060] In one embodiment, the electrical control circuit is also connected to an alarm. The alarm is activated and sounds an alarm when the normally closed contact 45 is opened. In this embodiment, the alarm is an audible and visual alarm. The alarm is connected to the control circuit in parallel and is linked to the normally closed contact 45. That is, the on / off state of the normally closed contact 45 directly controls the power supply of the alarm.

[0061] When the multi-stage screw conveyor 5 is in normal operation and no sludge leakage occurs: the safety bolt 41 in the screw protection device is locked, the spring 46 remains compressed, and the normally closed contact 45 is always closed.

[0062] The normally closed contact 45 keeps the control circuit of the electrical system conducting, and the current flows smoothly through the contactor coil. When the main contact 45 of the contactor closes, the main circuit is connected, and the drive motor of the screw conveyor 5 receives power and operates normally.

[0063] At this time, the alarm is in a power-off standby state and does not issue an alarm prompt because there is no reverse trigger signal in the control circuit (or the parallel branch is not connected).

[0064] When sludge leaks at the spiral joint due to quality issues, lifting the movable cover plate 1 and pulling the rope 3, thereby opening the safety bolt 41 of the spiral protection device, the coordination logic of each component changes as follows:

[0065] After the safety bolt 41 is pulled open, the compression spring 46 inside the spiral protection device quickly rebounds, pushing the mechanical structure to open the normally closed contact 45, thus disconnecting the originally conductive control circuit.

[0066] After the control circuit is disconnected, the contactor coil is de-energized, the main contact 45 of the contactor is reset and disconnected, the main circuit of the screw conveyor 5 is de-energized, the drive motor stops running, the sludge stops being pushed, and the expansion of the leakage range is effectively contained.

[0067] When the normally closed contact 45 opens, its linked electrical signal triggers the parallel branch of the alarm to conduct (or the power supply of the alarm is switched through the control module). The alarm receives power and immediately starts the audible and visual alarm, such as flashing red warning lights and sounding a buzzer alarm, to transmit a fault signal to the on-site maintenance personnel and prompt them to carry out timely maintenance.

[0068] After the maintenance personnel have dealt with the sludge leakage fault, such as cleaning up the leaking sludge, replacing the damaged parts, and relocking the safety bolt 41 of the spiral protection device, the safety bolt 41 is relocked, pushing the spring 46 to reset, and the normally closed contact 45 returns to the closed state under mechanical force, and the control circuit of the electrical system is reconnected.

[0069] After the control circuit is activated, the contactor coil is re-energized, the main contact 45 closes, and the screw conveyor 5 drive motor is powered back up, allowing the equipment to restart. Simultaneously, as the control circuit returns to normal, the alarm signal disappears, the alarm stops, and the device returns to standby mode, awaiting the next fault trigger.

[0070] It should be noted that the above description of the disclosed embodiments enables those skilled in the art to implement or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A protective device for a multi-stage screw conveyor for sludge, characterized in that, Includes a movable cover plate for sealing the screw conveyor and a screw protection unit that is linked to the movable cover plate; The movable cover plate is connected to a transmission component at its end. The spiral protection unit is equipped with an elastic component and a normally closed contact. The spiral protection unit is also equipped with a locking component that is linked to the transmission component. The normally closed contact is connected in series in the electrical control circuit of the drive motor of the spiral conveyor. When sludge leakage inside the screw conveyor generates thrust that lifts the movable cover plate, the movable cover plate triggers the locking element to unlock via a transmission component, causing the elastic element to drive the normally closed contact to open, thereby cutting off the electrical control circuit to stop the drive motor from operating.

2. The protective device for a multi-stage screw conveyor for sludge according to claim 1, characterized in that, The electrical control circuit is also connected to an alarm. When the normally closed contact is opened, the alarm is activated and sounds an alarm.

3. The protective device for a multi-stage screw conveyor for sludge according to claim 1, characterized in that, It also includes a breakable connector that connects the movable cover plate to the screw conveyor body, the breakable connector breaking when the movable cover plate is lifted.

4. The protective device for a multi-stage screw conveyor for sludge according to claim 3, characterized in that, The easily breakable connector is a plastic bolt, and the breaking strength of the plastic bolt is less than the withstand strength of the connection between the movable cover plate and the screw conveyor body.

5. A protective device for a multi-stage screw conveyor for sludge according to claim 1, characterized in that, The spiral protection unit also includes a housing, in which the elastic element, normally closed contact and locking element are all encapsulated. The housing is provided with a guide hole for the locking element to be inserted or withdrawn.

6. A protective device for a multi-stage screw conveyor for sludge according to claim 5, characterized in that, The transmission component is a pull rope, one end of which is fixed to the end of the movable cover plate, and the other end is connected to the locking component of the spiral protection unit; when the movable cover plate is lifted, the pull rope pulls the locking component to disengage from the locked state.

7. A protective device for a multi-stage screw conveyor for sludge according to claim 6, characterized in that, The spiral protection unit also includes a baffle located inside the housing. The elastic element is a spring, and the locking element is a safety bolt. One end of the spring is connected to the housing, and the other end of the spring is connected to the baffle. The baffle is connected to the normally closed contact. When the safety bolt is locked, it contacts the baffle and compresses the spring to close the normally closed contact. When the safety bolt is unlocked, the spring rebounds and pushes the baffle to reset, thus opening the normally closed contact.

8. A protective device for a multi-stage screw conveyor for sludge according to claim 7, characterized in that, Two springs are provided, and the two springs are respectively connected to the upper and lower parts of the baffle.

9. A protective device for a multi-stage screw conveyor for sludge according to claim 1, characterized in that, The movable cover plate is hinged to the cover plate on the screw conveyor.

10. A protective device for a multi-stage screw conveyor for sludge according to any one of claims 1-9, characterized in that, The electrical control circuit includes a main power switch, a main circuit, and a control circuit. The main circuit is connected in series with the main power switch, the main contact of the contactor, and the drive motor. The control circuit is connected in series with the main power switch, the fuse, the stop button, the start button, the contactor coil, and the normally closed contact. The contactor coil is connected in parallel with a contactor auxiliary normally open contact to achieve self-locking.

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