Fan-shaped ash scraper operation control device and control method thereof

Abstract

The invention relates to the technical field of converter steelmaking flue gas purification equipment, in particular to a fan-shaped ash scraper operation control device, when a motor drives a fan-shaped ash scraper to rotate forwards and backwards through a main speed reducer, the main speed reducer drives a limiting induction piece to rotate through a master speed reducer, and a first limiting induction rod is installed on the limiting induction piece; a first installation groove is formed in the proximity switch support, the first limiting induction rod swings in the first installation groove, a left in-place proximity switch is installed at the left end of the first installation groove, a right in-place proximity switch is installed at the right end of the first installation groove, a second limiting induction rod is further installed on the limiting induction piece, and a second installation groove is further formed in the proximity switch support. The second limiting induction rod swings in the second installation groove, a left limit proximity switch is installed at the left end in the second installation groove, and a right limit proximity switch is installed at the right end in the second installation groove. The invention further relates to a control method of the fan-shaped ash scraper operation control device.

Description

Technical Field

[0001] This invention relates to the technical field of converter steelmaking flue gas purification equipment, specifically to an operation control device and control method for the fan-shaped scraper of an electrostatic precipitator in a converter dry dust removal system, which is particularly suitable for precise control and safety protection of the reciprocating operation of the fan-shaped scraper. Background Technology

[0002] In the dry dust removal process of converters, the electrostatic precipitator is the core equipment for fine dust removal. The fan-shaped scraper (hereinafter referred to as the fan scraper) is responsible for removing the dust deposited on the anode plate. The reliability of its reciprocating cycle operation is directly related to the stability of the electrostatic precipitator and even the entire converter production.

[0003] Traditional fan scrapers employ a single-limit control mode. This involves a master reducer connected to the main reducer driving a limit sensor to rotate. A single sensing rod on the sensor triggers a single proximity switch on the proximity switch bracket, thereby controlling the forward and reverse rotation of the main reducer and achieving the reciprocating operation of the fan scraper. However, this single-limit control has a significant drawback: if the proximity switch fails due to loosening, damage, or sensor rod malfunction, the PLC will not receive the direction-switching signal, causing the fan scraper motor to continuously run in one direction. The fan scraper will continue to run to the mechanical limit of the gear ring, leading to "tooth skipping" and "tooth knocking," and in severe cases, causing major mechanical failures such as broken gear teeth, spindle deformation, and broken bearing seat bolts.

[0004] These types of failures all occur inside the electrostatic precipitator. Diagnosis and handling require shutdown and cooling before entering the equipment for repairs. This is not only time-consuming and labor-intensive, but also causes unplanned shutdowns of the converter, which has a huge impact on the continuous production of steel enterprises. Therefore, there is an urgent need for a fan-shaped scraper operation control scheme that can fundamentally prevent such single-point failures. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: in view of the shortcomings of the prior art, the present invention provides a fan-shaped scraper operation control device, which adds limit position protection through hardware redundancy design and realizes fault diagnosis and emergency shutdown by combining software logic interlock, thus building a double safety barrier, effectively preventing equipment damage caused by the failure of a single limit position, significantly improving the reliability and safety of fan scraper operation, and reducing production losses caused by equipment failure.

[0006] The technical solution adopted in this invention is: a fan-shaped scraper operation control device. When the motor drives the fan-shaped scraper to move forward and backward through the main reducer, the main reducer drives the limit sensor to rotate through the master reducer. A first limit sensor rod is installed on the limit sensor. A first mounting slot is on the proximity switch bracket. The first limit sensor rod swings in the first mounting slot. A left-end proximity switch is installed at the left end of the first mounting slot, and a right-end proximity switch is installed at the right end of the first mounting slot. A second limit sensor rod is also installed on the limit sensor. A second mounting slot is also on the proximity switch bracket. The second limit sensor rod swings in the second mounting slot. A left limit proximity switch is installed at the left end of the second mounting slot, and a right limit proximity switch is installed at the right end of the second mounting slot. The left-end proximity switch, right-end proximity switch, left limit proximity switch, right limit proximity switch, and motor electrical signal are connected to a PLC.

[0007] The proximity switch bracket is a dual limit control device, which is a door-shaped structure made of steel strip. The top of the door-shaped structure has two parallel arc-shaped slots, one of which is a first mounting slot and the other is a second mounting slot. The ends of the first and second mounting slots are flat and burr-free, and the length is reserved for limit adjustment.

[0008] A control method for a fan-shaped scraper operation control device includes the following contents. S1. Normal reciprocating operation: The PLC controls the motor to start in the forward direction (the forward direction can be manually set to counterclockwise or clockwise; in this embodiment, the leftward swing of the first limit sensor rod is taken as the forward direction, but it can also be set to the rightward swing of the first limit sensor rod). When the first limit sensor rod triggers the left-end proximity switch, the left-end proximity switch sends a left-end signal to the PLC, and the PLC controls the motor to stop. After a delay, it starts in the reverse direction (runs to the right). When the first limit sensor rod triggers the right-end proximity switch, the right-end proximity switch sends a right-end signal to the PLC, and the motor stops and, after a delay, reverses again, and so on. S2, Limit Position Protection: When the left or right limit proximity switch malfunctions, causing the fan scraper to continue running beyond the normal limit position, the second limit sensor will trigger the corresponding left or right limit proximity switch. After receiving the left or right limit signal from the left or right limit proximity switch, the PLC will immediately issue an emergency stop command to the motor and then control the motor to start in the opposite direction, so that the fan scraper returns to the safe area. S3. Signal Interlocking and Fault Diagnosis: The PLC program is equipped with interlocking logic: continuously monitoring the left position signal, right position signal, left limit signal, and right limit signal. If two theoretically mutually exclusive signals are detected, it is determined that there is a system logic error or hardware fault. The PLC immediately issues an interrupt command to stop the motor in an emergency and triggers an alarm to remind the operator to check. The two theoretically mutually exclusive signals include receiving the left position signal and the right limit signal within a set time, and receiving the right position signal and the left limit signal within a set time.

[0009] The core structure of the fan-shaped scraper operation control device of the present invention includes a motor, a main reducer, a master reducer, a limit sensor, a proximity switch bracket, and a PLC. The connection and design features of each component are as follows: Drive and sensing structure: The motor drives the fan-shaped scraper to reciprocate in both forward and reverse directions through the main reducer. The main reducer also drives the master reducer to run. The output end of the master reducer is connected to the limit sensor, which drives the limit sensor to rotate synchronously.

[0010] Dual-sensor design: A first limit sensor and a second limit sensor are fixedly installed on the limit sensor. The two sensor rods swing synchronously with the rotation of the limit sensor, corresponding to the position detection and limit protection functions respectively.

[0011] Dual mounting slot proximity switch bracket: The proximity switch bracket is a dual limit control device. It is made of steel strip into a doorway structure. There are two parallel arc-shaped slots on the top, which are the first mounting slot and the second mounting slot. The first mounting slot is adapted to the swing trajectory of the first limit sensing rod, and the second mounting slot is adapted to the swing trajectory of the second limit sensing rod.

[0012] The four-level proximity switch layout is as follows: a left-end proximity switch is installed at the left end of the first mounting slot, and a right-end proximity switch is installed at the right end, used to detect the normal reciprocating position of the fan wiper; a left-limit proximity switch is installed at the left end of the second mounting slot, and a right-limit proximity switch is installed at the right end, used to detect the limit position of the fan wiper's overtravel operation; all mounting slots are machined, with smooth, burr-free ends, and the length of the slot is reserved for limit adjustment, facilitating on-site installation and precise calibration of the proximity switches.

[0013] Electrical control connection: The signal output terminals of the left limit proximity switch, right limit proximity switch, left limit proximity switch, and right limit proximity switch are all electrically connected to the input module of the PLC. The output module of the PLC is electrically connected to the motor driving the fan-shaped scraper, realizing real-time acquisition of all limit signals and precise control of the motor.

[0014] Based on the above-mentioned device, the present invention also provides a corresponding control method, including three core steps: normal reciprocating operation, limit position protection, and signal interlocking and fault diagnosis, constructing a three-level control strategy of "position control as the main method, limit protection as the auxiliary method, and logic interlocking as a fallback": The beneficial effects of this invention are as follows: Compared with the traditional single-limit control scheme, the fan-shaped scraper operation control device and control method of this invention have the following significant advantages: 1. Hardware redundancy protection to eliminate single-point failure at the source: Through the hardware design of dual sensing rods, dual mounting slots and four-level proximity switches, the position detection and limit protection functions are separated in physical space and electrical circuit. This avoids the problem of equipment failure caused by the failure of a single sensor in traditional single limit control, and completely eliminates serious mechanical accidents such as "tooth skipping", "tooth breaking" and gear tooth breakage caused by overtravel of the fan scraper.

[0015] 2. Three-level control strategy with progressive safety protection: A three-level control logic is constructed, consisting of "position control as the main method, limit protection as the auxiliary method, and logic interlocking as a backup method". During normal operation, the position proximity switch achieves precise reciprocating control. When the position switch fails, the limit proximity switch achieves over-range emergency protection. When the sensor or line fails, the interlocking logic achieves fault diagnosis and emergency shutdown. The progressive protection ensures the safety of the fan and scraper operation.

[0016] 3. Simple structure, convenient modification and installation: The proximity switch bracket is made of steel strip into a doorway structure. The machined double arc-shaped mounting groove has a reserved adjustment margin. The end is flat and burr-free. It can be directly modified and installed on the basis of the existing fan-shaped scraper equipment without making major adjustments to the core drive structure. The modification cost is low and the construction period is short.

[0017] 4. Precise fault location and significantly enhanced maintainability: The PLC's interlock logic can identify various signal faults and display the specific fault signal combinations synchronously through the host computer human-machine interface. Operators do not need to check sensors and lines one by one, and can directly locate the fault point, which greatly shortens the fault diagnosis and repair time and reduces equipment maintenance costs.

[0018] 5. Improved production stability and significant economic benefits: After this device is put into use, it can effectively reduce unplanned downtime and major equipment repairs of the converter caused by fan scraper failure, ensure the continuous and stable operation of the converter dry dust removal system and the entire converter production, reduce long-term production losses, and extend the service life of the fan scraper and electrostatic precipitator, thus having significant economic benefits and industrial practical value. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the fan-scraper master reducer structure of the present invention; Figure 2 This is a schematic diagram of the three-view structure of the dual limit control device of the present invention; Figure 3 This is a logic flowchart of the control method of the present invention.

[0021] Among them, 1. Left limit proximity switch, 2. Right limit proximity switch, 3. Left limit proximity switch, 4. Right limit proximity switch, 5. Proximity switch bracket, 6. Limit sensor, 7. Limit sensor rod installation position, 8. Fan-shaped scraper shaft, 9. First mounting slot, 10. Second mounting slot. Detailed Implementation

[0022] 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.

[0023] Device installation and commissioning: 1. Proximity switch bracket installation: The portal-type proximity switch bracket made of steel strip is fixed to the bracket base next to the master reducer with bolts and nuts, ensuring that the bracket is installed firmly without any loosening or offset.

[0024] 2. Proximity switch installation: Install the left and right end-position proximity switches at the left and right ends of the first mounting slot using fasteners, respectively. Install the left and right limit proximity switches at the left and right ends of the second mounting slot, respectively. Adjust the position of each proximity switch in the mounting slot according to the normal operating stroke and limit protection stroke of the fan scraper to ensure that the end-position proximity switch is accurately triggered when the first limit sensing rod swings to the normal end point, and the limit proximity switch is accurately triggered when the second limit sensing rod exceeds the preset distance. After adjustment, tighten the fasteners.

[0025] 3. Electrical Connection: Connect the cables of the left limit proximity switch, right limit proximity switch, left extreme proximity switch, and right extreme proximity switch to the DI input module of the PLC to complete the wiring of the limit signals; connect the PLC's DO output module to the controller of the fan drive motor to complete the wiring of the motor control signals. After wiring, check whether the wiring connection is firm to avoid poor contact.

[0026] 4. PLC program debugging: Load the preset control program into the PLC, including normal reciprocating operation logic, limit protection logic, and signal interlock fault diagnosis logic. Set parameters such as motor start / stop delay time and mutual exclusion signal detection set time. Simulate triggering each proximity switch signal through the PLC to test whether the motor start / stop, direction switching, emergency stop, and alarm functions are normal, and ensure that all control logic operates without errors.

[0027] Field Application Examples A dual-limit control device for the fan scraper of a converter dry electrostatic precipitator includes a fan scraper drive mechanism, a master reducer, and a sensing element. Its improvement lies in the inclusion of a double-row mounting slot-type proximity switch bracket.

[0028] The bracket has two rows of parallel elongated mounting slots: a first mounting slot (position slot) and a second mounting slot (limit slot). A left-position proximity switch and a right-position proximity switch are respectively installed at both ends of the first mounting slot; a left-limit proximity switch and a right-limit proximity switch are respectively installed at both ends of the second mounting slot. The mounting slots are machined and have smooth edges, providing a precise and adjustable fixing reference for the installation position of the proximity switches.

[0029] The sensing element is equipped with a sensing rod that can sense the four proximity switches mentioned above.

[0030] The signal output terminals of the left and right position proximity switches and the left and right limit proximity switches are all connected to the input module of the programmable logic controller (PLC). The PLC output module controls the start, stop, and direction of the fan drive motor through the motor driver.

[0031] A control method for a fan-shaped scraper operation control device includes the following steps: S1: Normal reciprocating operation. The PLC controls the fan motor to start in the forward direction (e.g., to the left). When the sensor triggers the left-end proximity switch, the PLC controls the motor to stop, and after a delay, it starts in the reverse direction (to the right). When the right-end proximity switch is triggered, the motor stops and reverses again, thus cycling.

[0032] S2: Limit Position Protection. If the fan blades exceed the normal stop point and continue to operate in one direction due to a malfunction of the left (or right) limit proximity switch, the sensing rod will trigger the corresponding left (or right) limit proximity switch. After receiving the limit signal, the PLC will immediately issue an emergency stop command and then automatically control the motor to start in the opposite direction, causing the fan blades to return to the safe area.

[0033] S3: Signal Interlocking and Fault Diagnosis. The PLC program is equipped with interlocking logic: continuously monitoring combinations of left and right position signals, left and right limit signals, and arbitrary position signals combined with opposite direction limit signals. If two theoretically mutually exclusive signals are detected simultaneously as "true" (e.g., "left position" and "right position" are triggered simultaneously), it is determined to be a system logic error or hardware fault. At this time, the PLC immediately issues an interrupt command to stop the fan motor immediately and triggers an audible and visual alarm on the host computer's human-machine interface (HMI), clearly indicating the fault type (e.g., "left and right position signal conflict"), reminding the operator to check.

[0034] The fan-shaped dust scraper operation control device of the present invention was upgraded and put into use on the No. 1, No. 2 and No. 3 electrostatic precipitators in the North Zone of the steelmaking plant of Shanxi Taigang Stainless Steel Co., Ltd. in July 2020. During the actual operation for more than five years, the upgraded fan-shaped dust scrapers have not experienced any mechanical failures such as tooth loss, tooth skipping, or gear tooth breakage caused by limit switch failure. The operation stability of the electrostatic precipitators has been significantly improved, and the unplanned downtime of the converter dry dust removal system has been greatly reduced.

[0035] During field application, a fault occurred in the right-end proximity switch circuit due to poor contact. The fan scraper exceeded the right end point and continued to run. Subsequently, the second limit sensor rod triggered the right limit proximity switch. The PLC immediately controlled the motor to stop urgently and start in reverse. The fan scraper quickly returned to the safe area. At the same time, the host computer human-machine interface displayed "Right end signal missing, right limit protection triggered". The operator quickly located the circuit fault based on the alarm information and completed the repair. The entire fault handling process took only 15 minutes and did not affect the converter production, which fully verified the effectiveness, reliability and practicality of the invention.

[0036] Industrial Applicability: The fan-shaped scraper operation control device of this invention is suitable for the control and protection of the fan-shaped scraper in electrostatic precipitators of various converter dry dust removal systems. It can also be extended to other industrial fields where reciprocating operation is required and overtravel protection is necessary. This device has a simple structure, low modification cost, and convenient installation and commissioning. It can be quickly implemented on the basis of existing equipment, and after being put into use, it can significantly improve the safety and stability of equipment operation, reduce downtime losses due to failures, and lower equipment maintenance costs. It has broad industrial application prospects and practical value.

Claims

1. A fan-shaped scraper operation control device, wherein when the motor drives the fan-shaped scraper to move forward and reverse through a main reducer, the main reducer drives a limit sensor to rotate through a master reducer; a first limit sensing rod is installed on the limit sensor; a first mounting groove is provided on a proximity switch bracket; the first limit sensing rod swings in the first mounting groove; a left-end proximity switch is installed at the left end of the first mounting groove; and a right-end proximity switch is installed at the right end of the first mounting groove, characterized in that: The limit sensor is also equipped with a second limit sensor rod, and the proximity switch bracket is equipped with a second mounting slot. The second limit sensor rod swings in the second mounting slot. The left end of the second mounting slot is equipped with a left limit proximity switch, and the right end of the second mounting slot is equipped with a right limit proximity switch. The left limit proximity switch, the right limit proximity switch, the left limit proximity switch, the right limit proximity switch, and the motor electrical signal are connected to the PLC.

2. The fan-shaped scraper operation control device according to claim 1, characterized in that: The proximity switch bracket is a dual limit control device, which is a door-shaped structure made of steel strip. The top of the door-shaped structure has two parallel arc-shaped slots, one of which is a first mounting slot and the other is a second mounting slot. The ends of the first and second mounting slots are flat and burr-free, and the length is reserved for limit adjustment.

3. A control method for the fan-shaped scraper operation control device as described in claim 1, characterized in that: Includes the following content S1. Normal reciprocating operation: The PLC controls the motor to start in the forward direction. When the first limit sensor triggers the left position proximity switch, the left position proximity switch sends a signal to the PLC to reach the left position. The PLC controls the motor to stop. After a delay, it starts in the reverse direction. When the first limit sensor triggers the right position proximity switch, the right position proximity switch sends a signal to the PLC to reach the right position. The motor stops and, after a delay, reverses again. This cycle repeats. S2, Limit Position Protection: When the left or right limit proximity switch malfunctions, causing the fan scraper to continue running beyond the normal limit position, the second limit sensor will trigger the corresponding left or right limit proximity switch. After receiving the left or right limit signal from the left or right limit proximity switch, the PLC will immediately issue an emergency stop command to the motor and then control the motor to start in the opposite direction, so that the fan scraper returns to the safe area. S3. Signal Interlocking and Fault Diagnosis: The PLC program is equipped with interlocking logic: continuously monitoring the left position signal, right position signal, left limit signal, and right limit signal. If two theoretically mutually exclusive signals are detected, it is determined that there is a system logic error or hardware fault. The PLC immediately issues an interrupt command to stop the motor in an emergency and triggers an alarm to remind the operator to check. The two theoretically mutually exclusive signals include receiving the left position signal and the right limit signal within a set time, and receiving the right position signal and the left limit signal within a set time.

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