Method and device for detecting the stop of a valve shaft of a cinder valve

Abstract

This invention provides a method and apparatus for detecting the stoppage of an ash discharge valve shaft. The method involves collecting signals generated when the ash discharge valve shaft rotates; calculating the actual time T for one revolution of the shaft based on these signals; and comparing this actual time T with a preset time T0. If the actual time T is greater than the lower limit of the preset time T0, the ash discharge valve is considered stopped. By collecting and analyzing the signals generated when the ash discharge valve shaft rotates, the actual time T for one revolution can be determined. Comparing the actual time T with the preset time T0 allows for the assessment of the ash discharge valve's status, facilitating timely intervention, significantly improving detection accuracy and response speed, and reducing safety hazards caused by dust accumulation.

Description

Technical Field

[0001] This invention relates to the field of dust removal technology, and in particular to a method and apparatus for detecting the stoppage of the ash discharge valve shaft. Background Technology

[0002] In industrial dust removal and pulverized coal conveying control systems, the ash discharge valve, as a core device for airlocking and ash discharge, is crucial for real-time monitoring of its operating status to reduce dust accumulation and lower the probability of dust explosions. The ash discharge valve is typically driven by a motor that, through a reducer, rotates a shaft at a slow, uniform speed, evenly discharging dust from the upper hopper to the lower conveying pipe or dust collection box. However, due to the often high concentration of dust, severe vibration, and temperature fluctuations in the operating environment, the ash discharge valve is prone to abnormal shutdowns during long-term operation, such as mechanical jamming, reducer failure, transmission chain breakage, or rotating shaft breakage.

[0003] In related technologies, the monitoring of ash discharge valve operation typically only determines whether the basic electrical circuit (such as the contactor) is engaged, and cannot effectively determine whether the mechanical structure on site is actually rotating. When a reducer malfunctions, mechanical structure is damaged, or the main electrical circuit fails, the control circuit cannot alarm, leading to an abnormal shutdown of the ash discharge valve. If this is not detected in time during personnel inspections, it will result in a large accumulation of flammable dust, increasing the probability of major safety accidents such as dust explosions and equipment damage. Summary of the Invention

[0004] This invention provides a method and apparatus for detecting the stoppage of the ash discharge valve shaft, so as to improve the accuracy and response speed of the ash discharge valve operation status detection and reduce the safety risk of dust accumulation caused by abnormal shutdown of the ash discharge valve.

[0005] On one hand, the present invention provides a method for detecting the stoppage of the ash discharge valve shaft, comprising: Collect the signal generated when the shaft of the ash discharge valve rotates; The actual time T for the ash discharge valve shaft to rotate one revolution is calculated by the signal generated when the shaft of the ash discharge valve rotates. The actual time T for the ash discharge valve shaft to rotate one revolution is compared with the preset time T0 for the ash discharge valve shaft to rotate one revolution. If the actual time T is greater than the lower limit of the preset time T0, it indicates that the ash discharge valve is in a stopped state.

[0006] In one embodiment of the present invention, the signal generated when the shaft of the ash discharge valve rotates includes: Acquire the digital pulse signal generated by the proximity switch each time the rotating sensing contact passes by; The digital pulse signal is acquired to form a pulse sequence consisting of alternating high and low levels.

[0007] In one embodiment of the present invention, the actual time T for the ash discharge valve shaft to rotate one revolution is obtained by calculating the interval between the rising edges of two adjacent pulse signals using a pulse sequence.

[0008] In one embodiment of the present invention, the preset time T0 is set to 6s to match the extremely low-speed operation of the ash discharge valve.

[0009] In one embodiment of the present invention, after obtaining the actual time T for the ash discharge valve shaft to rotate one revolution, the method further includes: setting a continuous timeout period counter N; when the actual time obtained in a single calculation satisfies the relationship T>T0, controlling the value of the continuous timeout period counter N to accumulate by 1; when the value of the continuous timeout period counter N reaches a preset number of continuous timeout periods, it is determined that the rotating shaft is in a stopped state.

[0010] On the other hand, the present invention provides a detection device for the stopping of the ash discharge valve shaft, comprising: The mounting base is fixedly installed on the valve seat of the ash discharge valve; A rotary sensing contact is fixedly mounted on the rotating shaft of the ash discharge valve and rotates synchronously with the rotating shaft; A proximity switch is mounted on the mounting base, and a preset distance is maintained between the sensing surface of the proximity switch and the rotation trajectory of the rotary sensing contact. The PLC control system is electrically connected to the proximity switch and is used to receive the signal generated by the proximity switch each time the rotary sensing contact passes by. Based on two adjacent signals, the system calculates the actual time T for the ash discharge valve shaft to rotate one revolution. The system compares the actual time T for the ash discharge valve shaft to rotate one revolution with the preset time T0 for the ash discharge valve shaft to rotate one revolution. Based on the comparison result, the system determines the operating status of the ash discharge valve.

[0011] In one embodiment of the present invention, the mounting base includes a vertical plate and a horizontal plate. The horizontal plate is connected to the valve seat of the ash discharge valve. The vertical plate and the horizontal plate are vertically connected to form an L-shape or a T-shape. The proximity switch is mounted on the vertical plate.

[0012] In one embodiment of the present invention, a strip-shaped hole is provided on the horizontal plate, and the strip-shaped hole is used to adjust the distance between the mounting base and the rotating sensing contact.

[0013] In one embodiment of the present invention, the distance between the sensing surface of the proximity switch and the rotary sensing contact is 4-8 mm.

[0014] In one embodiment of the present invention, the detection device for the ash discharge valve shaft stopping further includes an alarm light, which is connected to the PLC control system and is used to alarm for abnormal operating conditions.

[0015] The beneficial effects of the present invention are as follows: The present invention proposes a method and device for detecting the stoppage of the ash discharge valve shaft. By collecting the signal generated when the ash discharge valve shaft rotates, the actual time T for the ash discharge valve shaft to rotate one revolution can be obtained by analyzing the signal. Then, the actual time T is compared with the preset time T0, thereby determining the state of the ash discharge valve, which facilitates timely handling, significantly improves the accuracy and response speed of detection, and reduces safety hazards caused by dust accumulation. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0017] In the attached diagram: Figure 1 A schematic diagram of the structure of a detection device for the stoppage of the ash discharge valve shaft provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the mounting base provided in one embodiment of the present invention.

[0018] The attached figures are labeled as follows: Ash discharge valve 1, rotating shaft 11, valve seat 12, mounting base 2, vertical plate 21, horizontal plate 22, strip hole 23, rotary sensing contact 3, proximity switch 4, alarm light 5. Detailed Implementation

[0019] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0020] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the shape, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0021] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the invention.

[0022] To enable those skilled in the art to better understand the technical solutions in this application, the custom terms, English abbreviations, and key technical concepts appearing in this application are first uniformly defined and explained. In this application, a Programmable Logic Controller (PLC) refers to an industrial digital electronic computer that serves as the core of a control system. It receives pulse signals generated by a proximity switch through a digital input module, and runs time interval calculation programs, power-on delay protection logic, and signal redundancy processing logic in its internal central processing unit. Finally, it sends control commands to external actuators or alarm devices through a digital output module. In this application, a proximity switch refers to a non-contact position switch that operates based on the principle of electromagnetic induction. It internally includes a high-frequency oscillator, a trigger circuit, and an output amplifier. When a highly magnetic metal object approaches its sensing surface, eddy currents are generated inside the metal object, causing the oscillator to attenuate, thereby generating a switching signal level change.

[0023] In industrial dust removal, pneumatic conveying, and pulverized coal conveying control systems, the ash discharge valve, as a core component for ash removal, is crucial for real-time monitoring of its operating status to prevent dust accumulation, maintain negative pressure in the control system, and reduce the probability of dust explosions. The ash discharge valve is typically driven by a motor that, through a reducer, rotates a shaft at a slow, uniform speed, evenly discharging dust from the upper hopper to the lower conveying pipe or dust collection box. However, due to the often extremely high concentrations of dust, severe mechanical vibration, and temperature variations as high as 215°C, the ash discharge valve is highly susceptible to abnormal shutdowns during long-term operation, such as mechanical jamming, reducer shaft breakage, and transmission chain breakage.

[0024] To overcome the deficiencies in the aforementioned related technologies, this application provides a method for detecting the stoppage of the ash discharge valve shaft, comprising: Step S1: Collect the signal generated when the shaft of the ash discharge valve rotates.

[0025] Specifically, the proximity switch 4 is fixed on the mounting base 2, which is securely mounted on the valve seat 12 of the ash discharge valve 1. The rotary sensing contact 3 is coaxially fixed at the end of the rotating shaft 11. When the drive motor drives the rotating shaft 11 to rotate through the reducer, the rotary sensing contact 3 rotates synchronously.

[0026] First, the digital pulse signal generated by the proximity switch each time the rotating sensing contact 3 passes by is acquired. Whenever the rotating sensing contact 3 rotates past the sensing surface of the proximity switch 4, the internal oscillation circuit of the proximity switch 4 attenuates, triggering the circuit to flip and outputting a high-level signal. When the rotating sensing contact 3 rotates away from the sensing surface of the proximity switch 4, the proximity switch 4 returns to its initial state and outputs a low-level signal. Through this non-contact sensing method, the proximity switch 4 can continuously acquire digital pulse signals composed of alternating high and low levels and transmit them to the digital input module of the control system (such as a PLC system) via a shielded cable.

[0027] Then, the above digital pulse signals are formed into a pulse sequence consisting of alternating high and low levels.

[0028] During the monitoring of the ash discharge valve's operational status, sensors installed near the rotating shaft (such as proximity switches or photoelectric sensors) capture the raw digital pulse signals generated during shaft rotation in real time. To facilitate accurate identification and processing by the subsequent control system, this signal is conditioned and converted, regularized, and formed into a pulse sequence consisting of alternating high and low levels. In this pulse sequence, each level transition (e.g., from low to high) precisely corresponds to the mechanical action of the ash discharge valve shaft passing through a specific angle or completing a specific position. This regularly alternating high and low level waveform not only effectively filters out complex electromagnetic interference and noise in the field but also greatly improves the signal's anti-interference capability and transmission reliability. Subsequently, the control unit (such as a PLC or microcontroller) can directly read this standard pulse sequence and accurately deduce the actual time taken for a single rotation of the shaft by calculating the time interval between adjacent level transitions. This provides a solid and accurate underlying data foundation for subsequent speed calculations, abnormal condition judgments, and system interlock protection.

[0029] Step S2: Calculate the actual time T for the ash discharge valve shaft to rotate one revolution using the signal generated when the shaft rotates.

[0030] During the automated operation and status monitoring of the ash discharge valve, the control system collects pulse or position feedback signals generated during the rotation of the shaft in real time. Based on these continuous rotation signals, the control unit can accurately capture the actual time T taken for the shaft to complete one full 360° rotation. This key parameter T not only intuitively reflects the actual rotational speed and discharge frequency of the ash discharge valve, but also serves as an important basis for evaluating the stability of equipment operation, calculating instantaneous discharge volume, and judging whether there are abnormal operating conditions such as jamming or overload, thus providing reliable data support for the stable operation of the entire dust removal control system.

[0031] For example, the PLC system calls its internal high-speed counters and timers to capture the rising edge of the received digital pulse signal. By calculating the interval between the rising edges of two adjacent pulse signals using the pulse sequence, the actual time T for the ash discharge valve shaft to rotate one revolution is obtained.

[0032] In this embodiment, the actual time T is calculated as follows: the PLC system records the absolute timestamps of the rising edges of two adjacent digital pulse signals being triggered. Let the time of the i-th captured pulse rising edge be... , i-th The moment when the rising edge of the pulse is captured is The formula for calculating the actual time T for one revolution of shaft 11 is: T = In equation (1), T is the actual time for the rotating shaft 11 to rotate one revolution, in seconds (s). The absolute moment when the rising edge of the pulse is captured in the current cycle, in seconds (s). This is the absolute moment when the rising edge of the pulse was captured in the previous cycle, expressed in seconds (s). Using this formula, the PLC system can quantify the actual operating cycle of the rotating shaft 11 in real time with extremely high precision.

[0033] Step S3: Compare the actual time T for the ash discharge valve shaft to rotate one revolution with the preset time T0 for the ash discharge valve shaft to rotate one revolution. If the actual time T is greater than the lower limit of the preset time T0, it means that the ash discharge valve is in a stopped state.

[0034] Specifically, in the automated monitoring logic of the ash discharge valve's operating status, the control system dynamically compares and analyzes the real-time calculated actual time T for a single rotation of the shaft with the pre-set standard time T0 for a single rotation and its allowable lower limit threshold. When the actual time T is detected to be greater than the lower limit of the preset time T0, the control system can determine that the ash discharge valve is currently in a stopped state or has experienced a serious speed abnormality. If the ash discharge valve stops or its speed drops sharply due to internal material jamming, mechanical structure failure, or power failure of the drive motor, the actual time required to complete a single full rotation will inevitably increase significantly, even approaching infinity. Through this rigorous logic comparison and threshold triggering mechanism, the control system can accurately detect equipment shutdowns or abnormal operating conditions in real time, and then promptly trigger audible and visual alarms or automatically cut off relevant feeding programs. This effectively prevents serious production accidents caused by poor ash discharge, such as ash accumulation in the ash hopper, blockage of the control system, and even secondary dust pollution, thus providing a solid guarantee for the overall safety and stable operation of the dust removal control system.

[0035] This application adopts the principle of non-contact electromagnetic induction, which completely eliminates the mechanical wear and jamming risks of traditional contact detection devices and improves the working life in harsh industrial environments.

[0036] When the actual time T calculated by the PLC system satisfies the relationship T>T0, it indicates that the actual rotation cycle of the shaft 11 has significantly exceeded the upper limit of the safe operating cycle, meaning that the shaft 11 has experienced severe jamming, its speed has slowed down drastically, or it has completely stopped rotating. At this time, the PLC system determines that the shaft 11 is in a stopped state and immediately outputs a control signal through its digital output module to remind the staff. It can also drive the alarm light 5 to provide an immediate audible and visual alarm, prompting on-site operators and the central control room to take emergency measures.

[0037] If the actual time T satisfies the relationship T≤T0, then the rotating shaft 11 is determined to be in normal operating condition.

[0038] Specifically, if the calculated actual time T is less than or equal to the preset lower limit T0, it indicates that the rotational speed of shaft 11 is within the normal rated fluctuation range, and the equipment is operating well. The PLC system determines that shaft 11 is in normal operating condition, does not output an alarm signal, and automatically clears the timer to prepare for the next pulse cycle detection loop.

[0039] In some preferred embodiments, the preset time lower limit T0 is set to 6s.

[0040] Specifically, the ash discharge valve 1 is typically a very low-speed operating device, with a rated speed n generally around 10 r / min. Under single-contact operation and without considering deviation, the theoretical cycle of one normal rotation of the shaft 11 is 6 seconds. Therefore, precisely setting the preset lower limit value T0 to 6 seconds perfectly matches this low-speed operating characteristic. When the shaft 11 is operating normally, the interval T between the rising edges of adjacent pulses collected by the proximity switch 4 should be stable at around 6 seconds. Once a jam occurs causing a stop, the actual time T will quickly exceed 6 seconds. The PLC system can detect abnormal speed extremely sensitively by comparing the actual time T with 6 seconds. In contrast, if the threshold is set too low (e.g., 2 seconds), false alarms will be frequently triggered during normal low-speed operation; if it is set too high (e.g., 15 seconds), the alarm response will be severely delayed, making it impossible to cut off the feed in the early stages of a fault. Therefore, limiting T0 to 6 seconds is a key parameter for balancing detection sensitivity and system anti-interference capability.

[0041] In some embodiments, after obtaining the actual time T for one revolution of the ash discharge valve shaft, the method further includes: Set the continuous timeout period counter N and reset its initial value to 0.

[0042] When the actual time obtained from a single calculation satisfies the relationship T>T0, the value of the continuous timeout period counter N is incremented by 1, i.e., N=N+1 is executed.

[0043] Determine whether the current value of the continuous timeout period counter N has reached the preset number of continuous timeout periods.

[0044] If the value of the continuous timeout period counter N reaches the preset number of continuous timeout periods, the rotating shaft 11 is finally determined to be in a stopped state, and a control signal is output to control the alarm light 5 to sound an alarm.

[0045] If, during the accumulation of counter N, the calculated actual time recovers to satisfy the relationship T≤T0, then the value of the continuous timeout period counter N is cleared to zero, that is, N=0 is executed and the count is restarted.

[0046] In actual industrial settings, electromagnetic interference, momentary power grid fluctuations, or minute impurities in materials can cause a brief, transient pause in the rotating shaft 11. This pause is usually overcome automatically by the system's own driving torque within a very short time, restoring normal rotation. If an alarm were triggered immediately based solely on a single pulse interval T>T0, it would result in an extremely high false alarm rate, severely impacting production continuity. By introducing the aforementioned signal redundancy processing logic, the final stop alarm is only triggered when timeouts are detected for N consecutive rotation cycles (i.e., the rotating shaft 11 remains stopped or operates at extremely slow speeds for more than 6*Ns). This effectively filters out momentary electromagnetic interference and brief mechanical pauses, reducing the false alarm rate of the control system and ensuring the reliability of the alarm signal.

[0047] On the other hand, such as Figure 1 and Figure 2 As shown, the present invention also provides a detection device for the stopping of the rotating shaft of an ash discharge valve, including a mounting base 2, a proximity switch 4, a rotary sensing contact 3, and a PLC system. The mounting base 2 is disposed on the ash discharge valve 1; the proximity switch 4 is fixed on the mounting base 2, and the rotary sensing contact 3 is disposed on the rotating shaft 11 of the ash discharge valve 1; the control system (such as a PLC system) is electrically connected to the proximity switch 4.

[0048] Specifically, the proximity switch 4 is used to non-contactly acquire the digital pulse signal generated when the rotary sensing contact 3 rotates and transmit it to the PLC system. The PLC system is used to calculate the time interval between adjacent pulses based on the digital pulse signal to obtain the actual time T for the rotating shaft 11 to rotate one revolution, and to determine that the rotating shaft 11 is in a stopped state when the actual time T is greater than the preset lower limit value T0.

[0049] During operation, the sensing surface of proximity switch 4 maintains a non-contact, preset distance from the rotation trajectory of rotary sensing contact 3. Whenever the rotating shaft 11 drives the rotary sensing contact 3 past the sensing surface of proximity switch 4, proximity switch 4 generates a level signal and transmits it to the PLC system. The PLC system acquires this signal through a high-speed counting channel and uses an internal timer to calculate the time interval between the rising edges of two adjacent signals, thus obtaining the actual time T for one revolution of the rotating shaft 11. The PLC system compares the actual time T with the preset lower time limit T0 in real time. Once T > T0, it is determined that the rotating shaft 11 has stopped rotating, and the PLC system immediately outputs a control signal to close the relay. In some embodiments, the detection device further includes an alarm light connected to the PLC control system for alerting users to abnormal operating conditions. Turning on the power supply to the alarm light 5 activates a strong audible and visual alarm. This device has a compact structure and no mechanical friction pairs, reducing the probability of detection failure due to mechanical wear and lowering maintenance costs.

[0050] In some embodiments, the mounting base 2 consists of a vertical plate 21 and a horizontal plate 22. The horizontal plate 22 is connected to the valve seat 12 of the ash discharge valve. The vertical plate 21 and the horizontal plate 22 are vertically connected in an L-shape or T-shape. The proximity switch 4 is mounted on the vertical plate 21. The horizontal plate 22 has a strip hole 23. The vertical plate 21 is fixed by fasteners passing through the strip hole 23. The vertical plate 21 can slide along the strip hole 23 to adjust the radial distance between the proximity switch 4 and the rotary sensing contact 3, so that the radial distance is maintained within the sensing sensitivity range of 4mm to 8mm.

[0051] Specifically, in industrial dust removal sites, the ash discharge valve 1 experiences continuous and severe mechanical vibration due to fan suction and material falling. Long-term vibration can easily cause slight physical displacement of the mounting base 2, causing the radial distance between the proximity switch 4 and the rotary sensing contact 3 to deviate from the design value, leading to sensing failure or collision. To solve this mechanical displacement compensation problem, in this embodiment, the mounting base 2 adopts a unique L-shaped or T-shaped adjustment structure. The mounting base 2 includes a vertical plate 21 and a horizontal plate 22, which are vertically welded together. The horizontal plate 22 is attached to the valve seat 12 of the ash discharge valve 1, and a radially extending slot 23 is provided on the horizontal plate 22. Fastening bolts pass through this slot 23 to lock the horizontal plate 22 onto the valve seat 12. The proximity switch 4 is fixed to the vertical plate 21 by a nut. When the sensing distance needs to be adjusted, simply loosen the fastening bolts slightly, allowing the entire mounting base 2 to slide radially along the strip hole 23. This allows for extremely precise fine-tuning of the radial distance between the proximity switch 4 and the rotary sensing contact 3, keeping it perfectly within the optimal sensing sensitivity range of 4mm to 8mm. After adjustment, tighten the bolts again. This design not only simplifies installation but also provides mechanical displacement compensation, improving the detection stability of the device under long-term severe vibration.

[0052] In this embodiment, the rotary sensing contact 3 includes a non-metallic turntable coaxially fixedly mounted on the end of the rotating shaft 11, and an iron plate eccentrically embedded on the end face of the non-metallic turntable. The non-metallic turntable is made of MC nylon material, with a precision circular hole in its center. A bolt post is coaxially provided at the end of the rotating shaft 11. During assembly, the non-metallic turntable is fitted onto the bolt post of the rotating shaft 11 through its central circular hole and locked in place with a high-strength anti-loosening nut, ensuring extremely high coaxiality between the non-metallic turntable and the rotating shaft 11, and preventing loosening or relative slippage under long-term alternating torque and severe vibration. The proximity switch 4 is an electromagnetic proximity switch, securely mounted on the upright plate 21 of the mounting base 2, with its sensing end face aligned with the trajectory of the iron plate embedded in the non-metallic turntable. Because the nylon material is completely transparent to electromagnetic signals, the alternating magnetic field emitted by the electromagnetic proximity switch 4 can penetrate the nylon medium without damage, producing an extremely sensitive response only to the highly magnetically permeable iron plate. This structure not only completely eliminates the magnetic field interference of the large metal body of the rotating shaft 11, but its bolt-locking assembly method is also highly shock-resistant, making it very suitable for heavy-duty industrial environments.

[0053] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for detecting the stoppage of the ash discharge valve shaft, characterized in that, include: Collect the signal generated when the shaft of the ash discharge valve rotates; The actual time T for the ash discharge valve shaft to rotate one revolution is calculated by the signal generated when the shaft of the ash discharge valve rotates. The actual time T for the ash discharge valve shaft to rotate one revolution is compared with the preset time T0 for the ash discharge valve shaft to rotate one revolution. If the actual time T is greater than the lower limit of the preset time T0, it indicates that the ash discharge valve is in a stopped state.

2. The method for detecting the stoppage of the ash discharge valve shaft according to claim 1, characterized in that, The signal generated when the shaft of the ash discharge valve rotates includes: Acquire the digital pulse signal generated by the proximity switch each time the rotating sensing contact passes by; The digital pulse signal is acquired to form a pulse sequence consisting of alternating high and low levels.

3. The method for detecting the stoppage of the ash discharge valve shaft according to claim 2, characterized in that, The actual time T for the ash discharge valve shaft to rotate one revolution is obtained by calculating the interval between the rising edges of two adjacent pulse signals using a pulse sequence.

4. The method for detecting the stoppage of the ash discharge valve shaft according to any one of claims 1-3, characterized in that, The preset time T0 is set to 6s to match the extremely low-speed operation of the ash discharge valve.

5. The method for detecting the stoppage of the ash discharge valve shaft according to claim 3, characterized in that, After obtaining the actual time T for the ash discharge valve shaft to rotate one revolution, the method further includes: setting a continuous timeout period counter N; when the actual time obtained in a single calculation satisfies the relationship T>T0, controlling the value of the continuous timeout period counter N to increment by 1; when the value of the continuous timeout period counter N reaches the preset number of continuous timeout periods, it is determined that the rotating shaft is in a stopped state.

6. A detection device for the stopping of the rotating shaft of an ash discharge valve, characterized in that, include: The mounting base is fixedly installed on the valve seat of the ash discharge valve; A rotary sensing contact is fixedly mounted on the rotating shaft of the ash discharge valve and rotates synchronously with the rotating shaft; A proximity switch is mounted on the mounting base, and a preset distance is maintained between the sensing surface of the proximity switch and the rotation trajectory of the rotary sensing contact. The PLC control system is electrically connected to the proximity switch and is used to receive the signal generated by the proximity switch each time the rotary sensing contact passes by. Based on two adjacent signals, the system calculates the actual time T for the ash discharge valve shaft to rotate one revolution. The system compares the actual time T for the ash discharge valve shaft to rotate one revolution with the preset time T0 for the ash discharge valve shaft to rotate one revolution. Based on the comparison result, the system determines the operating status of the ash discharge valve.

7. The detection device for the stoppage of the ash discharge valve shaft according to claim 6, characterized in that, The mounting base includes a vertical plate and a horizontal plate. The horizontal plate is connected to the valve seat of the ash discharge valve. The vertical plate and the horizontal plate are vertically connected to form an L-shape or a T-shape. The proximity switch is mounted on the vertical plate.

8. The detection device for the stoppage of the ash discharge valve shaft according to claim 7, characterized in that, The horizontal plate is provided with a strip-shaped hole, which is used to adjust the distance between the mounting base and the rotating sensing contact.

9. The detection device for the stoppage of the ash discharge valve shaft according to claim 8, characterized in that, The distance between the sensing surface of the proximity switch and the rotary sensing contact is 4-8 mm.

10. The detection device for the stoppage of the ash discharge valve shaft according to claim 6, characterized in that, The detection device for the ash discharge valve shaft stopping also includes an alarm light, which is connected to the PLC control system and is used to alarm for abnormal operating conditions.

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