Powder conveyor for sulfanilic acid production

Abstract

The present application relates to the field of chemical powder machinery and automation control technology, in particular to a powder conveyor for p-aminobenzenesulfonic acid production, comprising a powder conveying execution, a resistance benchmark calibration, a real-time evaluation of material flowability and a self-adaptive state control module; the system calculates the dynamic flowability index by collecting the servo motor output torque and the strain gauge micro-strain value combined with the no-load benchmark; the core is to determine the degree of caking according to the index threshold value, control the motor high-frequency pulsation and superimpose the sine wave when the caking is mild, cooperate with the periodic shear extrusion of the wave-shaped notch of the blade to depolymerize the material, control the motor to reverse and reshape and make speed compensation operation when the bridging is serious; the present application realizes the real-time monitoring of the material flow state and the self-adaptive blockage removal in the pipe, eliminates the manual cover opening and blockage removal link, greatly reduces the downtime and eliminates the dust escape.

Description

Technical Field

[0001] This invention relates to the field of chemical powder machinery and automation control technology, specifically to a powder conveyor for the production of p-aminobenzenesulfonic acid. Background Technology

[0002] In continuous production and conveying environments of chemical powdered materials, powders such as p-aminobenzenesulfonic acid have the physical property of easily adhering after absorbing moisture, which can easily lead to local accumulation, agglomeration, and even the formation of strong bridging structures inside the pipe. To continuously convey such powders, existing solutions generally use traditional constant-speed screw conveyors, which use a drive motor to drive an internal screw shaft at a fixed speed and direction to forcefully push the material. Although this solution has basic continuous discharge capability under ideal conditions where the powder is dry and has good flowability, its single operating mode and lack of a real-time sensing mechanism for the pressure and flow status of the material inside the pipe cause a lag in the fault handling process. When slight agglomeration or severe bridging occurs inside the pipe, the equipment still maintains a constant thrust, causing the blockage to worsen rapidly. Ultimately, manual shutdown, opening the cover, disassembly, and clearing of the blockage are necessary. This method has a long maintenance cycle, reduces the overall operating efficiency of the production line, and the opening and cleaning process inevitably involves a large amount of dust escaping, causing environmental pollution and safety hazards.

[0003] Therefore, how to achieve real-time identification of the flow state during powder conveying and adaptively complete mechanical arch breaking and continuous conveying restoration without opening the cover, so as to significantly reduce downtime and prevent dust escape, has become an urgent technical problem to be solved. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a powder conveyor for the production of p-aminobenzenesulfonic acid. Specifically, the technical solution of the present invention includes: The powder conveying execution module includes a base, a conveying pipe fixed above it, a spiral shaft coaxially inserted inside the conveying pipe, a servo motor driving the spiral shaft, and strain gauges attached axially to the outer wall of the conveying pipe. The outer wall of the spiral shaft is provided with continuous spiral blades, and the outer edge is machined with continuous wavy notches; The resistance reference calibration module is used to control the servo motor to rotate at a steady speed under no-load conditions and record its no-load output torque and strain gauge micro-strain values ​​under no-load conditions. The real-time material flowability assessment module is used to control the motor to run at a preset base speed during normal conveying, and to collect its current output torque and current micro-strain value to calculate the dynamic flowability index. The adaptive state control module, based on a dynamic liquidity index, performs resonance-based or reversal-based reshaping and compensation control on the execution module, including: The mild clumping determination unit is used to determine mild clumping when the dynamic liquidity index is less than a preset first threshold and greater than or equal to a preset second threshold. The high-frequency pulsating resonance unit is used to control the motor to enter the high-frequency pulsating mode and superimpose a sinusoidal wave on the base speed when mild agglomeration is detected. The severe bridging determination unit is used to determine severe bridging when the dynamic liquidity index is less than a preset second threshold. The reversing reshaping compensation unit is used to control the motor to decelerate, reverse, and resume forward rotation in sequence when a severe bridging occurs, while also performing speed compensation increment operation.

[0005] In a preferred embodiment of the present invention, the conveying pipe is divided into a feeding section, a main conveying section and a discharging section. A feeding port is provided above the feeding section and a discharging port is provided below the discharging section. The wall thickness of the main conveying section is set to 3 mm. The strain gauge includes four strain gauge units that are equidistantly pasted along the outer wall of the main conveying section. The strain gauge units are covered with an epoxy resin protective layer.

[0006] In a preferred embodiment of the present invention, the resistance reference calibration module is used to: control the servo motor to drive the spiral shaft to rotate continuously at a stable speed of 50 r / min for 3 minutes under an unloaded state where no material enters the feed inlet; record the unloaded output torque of the servo motor at this speed in real time, and simultaneously record the unloaded micro-strain values ​​output by the four strain gauge units; and store the unloaded output torque and the unloaded micro-strain values ​​as reference parameters in the resistance reference calibration module.

[0007] In a preferred embodiment of the present invention, the real-time material flowability assessment module includes: a net propulsion torque calculation subunit, used to determine the net propulsion torque based on the current output torque and the no-load output torque; The characteristic deformation rate extraction subunit is used to extract the characteristic deformation rate based on the comprehensive characteristic deformation response of the current micro-strain value and the unloaded micro-strain value of the four strain gauge units; The dynamic liquidity index calculation subunit is used to determine the dynamic liquidity index based on the net propulsion torque and the characteristic deformation rate.

[0008] In a preferred embodiment of the present invention, the high-frequency pulsating resonance unit includes: a resonance frequency conversion subunit, used to extract a matching pulsating frequency based on the structural parameters of the wavy notch on the helical blade and the basic rotational speed of the helical shaft; The waveform superposition subunit is used to superimpose the sinusoidal rotational speed fluctuation with the fluctuation frequency onto the original base rotational speed, so that the period of the rotational speed fluctuation coincides with the period of the wave-shaped notch sweeping across a specific agglomerated area of ​​the pipe wall.

[0009] In a preferred embodiment of the present invention, the reverse reshaping compensation unit includes: a reverse bridge breaking subunit, which controls the servo motor to decelerate to a stop within 0.5s and then reverse at a speed of 30r / min for 2s, so that the spiral blades convey and peel off the material at the bridging part in the opposite direction to the feed port. The forward rotation recovery subunit is used to control the servo motor to resume forward rotation after the reverse rotation ends, and to accelerate to the base speed at an acceleration of 5r / s². The flow compensation calculation subunit is used to calculate the delivery deficit and speed compensation increment after the bridging is eliminated and the dynamic flow index recovers to above the first threshold. The compensation operation subunit is used to control the servo motor to operate by adding the speed compensation increment to the base speed until the material conveying of the current batch is completed.

[0010] In a preferred embodiment of the present invention, the flow compensation calculation subunit is used to: obtain the time value of the deceleration, reversal and recovery forward lifting process; extract the conveying volume deficit value based on the time value, and determine the speed compensation increment in combination with the remaining planned conveying time of the current batch of materials.

[0011] In a preferred embodiment of the present invention, the total length of the conveying pipe is 3m and the inner diameter is 200mm; the length of the main conveying section is 2m and the spacing between adjacent strain gauge units is 0.5m.

[0012] In a preferred embodiment of the present invention, the main body of the spiral shaft is made of a seamless steel pipe with an outer diameter of 60 mm and a wall thickness of 10 mm; the outer diameter of the spiral blade is 190 mm, and a radial gap of 5 mm is formed with the inner wall of the conveying pipe; the pitch of the spiral blade is set to 150 mm; the depth of the wavy notch is 5 mm, and the peak-to-valley distance between adjacent notches is 20 mm.

[0013] In a preferred embodiment of the present invention, the two ends of the spiral shaft protrude through the end caps of the conveying pipe and are supported by a first bearing seat and a second bearing seat; the first bearing seat and the second bearing seat are both fixedly connected to the base and are located 0.2m outside the two ends of the conveying pipe respectively; the first bearing seat adopts a structure combining a labyrinth seal and a lip seal to isolate dust.

[0014] The present invention has the following beneficial effects: 1. This invention calculates the dynamic flowability index by collecting the output torque of the motor and the micro-strain value of the strain gauge, realizing real-time monitoring of the material flow state; when it is determined to be slightly agglomerated, the motor is controlled to enter the high-frequency pulsation mode, and the material is periodically sheared and squeezed to deagglomerate in conjunction with the wavy notch on the spiral blade; this design can automatically handle the initial agglomeration in the pipe, avoid the blockage from worsening, completely eliminate the manual opening of the cover to clear the blockage, greatly reduce downtime and prevent dust from escaping; 2. This invention designs a reversal reshaping and compensation control mechanism to address the severe bridging problem that easily forms in powders. When severe bridging is detected, the control motor decelerates and reverses sequentially to pull back the bridging material and break the bridging, then resumes forward rotation. At the same time, the system calculates the conveying volume deficit during this process and automatically adds speed compensation increments to the base speed. This design accurately compensates for the flow gap caused by the fault without opening the cover for adaptive bridging, ensuring the stability of the conveying volume. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 This is a schematic diagram of the overall external structure of the device; Figure 2 This is a schematic diagram of the cross-sectional structure of the delivery pipe; Figure 3 This is a schematic diagram of the structure of the first bearing housing.

[0016] In the diagram: 1. Powder conveying execution module; 2. Base; 3. Conveying pipe; 4. Screw shaft; 5. Servo motor; 6. Strain gauge; 7. Spiral blade; 8. Wavy notch; 9. Feeding section; 10. Main conveying section; 11. Discharge section; 12. Feed inlet; 13. Discharge outlet; 14. Strain gauge unit; 15. Epoxy resin protective layer; 16. Seamless steel pipe; 17. End cap; 18. First bearing seat; 19. Second bearing seat; 20. Labyrinth seal; 21. Lip seal. Detailed Implementation

[0017] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. 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 should fall within the scope of protection of the present invention. Example

[0018] A powder conveyor for the production of p-aminobenzenesulfonic acid, comprising: Combination Figure 1 As shown, the powder conveying execution module 1 includes a base 2, a conveying pipe 3 fixed above it, a spiral shaft 4 coaxially inserted inside the conveying pipe 3, a servo motor 5 driving the spiral shaft 4, and a strain gauge 6 attached axially to the outer wall of the conveying pipe 3. Combination Figure 2 As shown, the outer wall of the spiral shaft 4 is provided with continuous spiral blades 7, and its outer edge is machined with continuous wavy notches 8; The resistance reference calibration module is used to control the servo motor 5 to rotate at a steady speed under no-load conditions and record its no-load output torque and the no-load micro-strain value of strain gauge 6. The real-time material flowability assessment module is used to control motor 5 to run at a preset base speed during normal conveying, and to collect its current output torque and current micro-strain value to calculate the dynamic flowability index. The adaptive state control module, based on the dynamic liquidity index, performs resonance-based arch-breaking or reversal reshaping and compensation control on execution module 1, including: The mild clumping determination unit is used to determine mild clumping when the dynamic liquidity index is less than a preset first threshold and greater than or equal to a preset second threshold. The high-frequency pulsating resonance unit is used to control motor 5 to enter the high-frequency pulsating mode and superimpose sinusoidal fluctuations on the base speed when mild agglomeration is detected. The severe bridging determination unit is used to determine severe bridging when the dynamic liquidity index is less than a preset second threshold. The reverse reshaping compensation unit is used to control motor 5 to decelerate, reverse, and resume forward rotation in sequence when severe bridging occurs, while also performing speed compensation incremental operation. This embodiment addresses the problems of easy adhesion, agglomeration, and bridging of p-aminobenzenesulfonic acid powder after absorbing moisture. It adopts a conveying execution structure with a wavy notch 8 on the outer edge of the spiral blade 7, and combines torque and strain signals to judge the material flow state. Compared with traditional spiral conveying equipment that only relies on constant speed conveying, this solution links agglomeration identification and conveying control to the same set of execution mechanisms. This allows mild agglomeration in the pipe to be handled by pulsating speed disturbance, and severe bridging to be handled by reverse reversal to break the arch. Moreover, the whole process does not require opening the cover for disassembly and cleaning, which can reduce downtime and the probability of dust escape. In this embodiment, the dynamic flowability index is used as a state quantity to characterize the propulsion load corresponding to the unit change in pressure on the pipe wall. When the material is in a normal continuous flow state, the material is propulsed uniformly, the lateral extrusion stress on the pipe wall is within the preset normal range and is stable, the characteristic deformation rate of the pipe wall is within the background noise range, and the propulsion torque is maintained in the normal working range. At this time, the dynamic flowability index remains above the first threshold. When the material absorbs moisture and slightly clumps, the clumps roll and compress inside the pipe, causing high-frequency fluctuations in the local stress on the pipe wall, with the fluctuation amplitude exceeding the preset normal range. This significantly increases the characteristic deformation rate, which is the denominator of the calculation model, and the dynamic flowability index drops sharply. When the material state further evolves and forms severe bridging, the material forms a solid arch bridge structure inside the pipe. Most of the propulsion force of the spiral shaft 4 is converted into strong lateral compression of the pipe wall by the bridging structure, causing the pipe wall deformation to increase continuously and rapidly. At this time, although the torque also increases, the rate of deterioration of the pipe wall deformation under pressure is significantly greater than the increase in torque, causing the dynamic flowability index to further decrease to the preset low value range. Therefore, the larger the value, the easier it is for the material to form a continuous flow when it is spirally propelled; the smaller the value, the easier it is for the material to be locally compacted, adhered, or form a bridging structure; the first threshold is used to distinguish between normal flow state and slightly agglomerated state, the second threshold is used to distinguish between slightly agglomerated state and severely bridging state, and the first threshold is greater than the second threshold. The two thresholds are determined as follows: First, multiple batches of p-aminobenzenesulfonic acid powder with a moisture content within the allowable range of the process are selected from the target production line for trial operation. During continuous conveying, the dynamic flowability index and the actual flow phenomena observed on site are recorded simultaneously. Then, the upper boundary of the index interval where local adhesion occurs but material can still be continuously discharged is determined as the first threshold, and the upper boundary of the index interval where obvious intermittent feeding, material accumulation, or reversal is required to resume conveying is determined as the second threshold. The control system takes the stable interval of multiple batches of data as the formal set value and writes it into the parameter table. Therefore, the role of the first threshold in the control process is to trigger high-frequency pulsation resonance processing in advance to suppress the continued development of mild agglomeration. The role of the second threshold in the control process is to trigger reversal reshaping and compensation control to prevent the bridging state from continuing to expand. In order to reduce misjudgment caused by single sampling fluctuations, the control system prefers to output the state judgment signal only after multiple consecutive sampling cycles meet the corresponding threshold relationship, and resumes the basic speed transmission after the judgment state is released. For example, in the same continuous conveying test of p-aminobenzenesulfonic acid powder, the traditional constant speed conveying equipment required a shutdown and manual cleaning of the bridging every 48 hours on average, which took about 2 hours each time and was accompanied by dust escaping. However, after adopting the solution of this embodiment, the system uses real-time monitoring of dynamic flowability index to trigger high-frequency pulsating resonance at the stage of slight agglomeration, which mechanically deagglomerates most of the agglomerates in the pipe. During the test period, no serious blockage requiring manual intervention occurred during 300 hours of continuous operation. The overall downtime of the equipment was reduced by more than 90%, and since there was no need to open the cover, dust escaping was effectively suppressed.

[0019] The conveying pipe 3 is divided into a feeding section 9, a main conveying section 10 and a discharging section 11. A feeding port 12 is provided above the feeding section 9 and a discharging port 13 is provided below the discharging section 11. The wall thickness of the main conveying section 10 is set to 3mm. The strain gauge 6 includes four strain gauge units 14 that are equidistantly pasted along the outer wall of the main conveying section 10. The strain gauge units 14 are covered with an epoxy resin protective layer 15. The conveying pipe 3 adopts a segmented structure. The feeding section 9 is used to receive p-aminobenzenesulfonic acid powder, the main conveying section 10 is used to complete material propulsion and status detection, and the discharge section 11 is used to stably feed material to subsequent equipment. After the wall thickness of the main conveying section 10 is set to 3mm, the pipe body can form a deformation that can be recognized by the strain gauge 6 when it is squeezed by the material, which facilitates the output of a stable signal by the strain gauge 6. The four strain gauge units 14 are evenly arranged along the main conveying section 10, which can correspond to the changes in pipe wall force at different axial positions. The epoxy resin protective layer 15 is used to isolate dust, moisture and cleaning liquid, reduce the drift of the sensor after being affected by the environment, and make the subsequent flowability calculation have a consistent signal source.

[0020] The resistance reference calibration module is used to: control the servo motor 5 to drive the screw shaft 4 to rotate continuously at a stable speed of 50 r / min for 3 minutes under no-load conditions when no material enters the feed inlet 12; record the no-load output torque of the servo motor 5 at this speed in real time, and at the same time record the no-load micro-strain values ​​output by the four strain gauge units 14; and store the no-load output torque and no-load micro-strain values ​​as reference parameters into the resistance reference calibration module. After the equipment is started and before material is fed into the feed inlet 12, the servo motor 5 drives the spiral shaft 4 to run at a constant speed of 50 r / min for 3 minutes, so that the basic friction state between the spiral blade 7 and the inner wall of the conveying pipe 3 is stabilized. During this stage, the control system records the motor output torque and the background micro-strain of the four strain gauge units 14, and writes them into the control system storage area as reference parameters. After this processing, the subsequent calculations do not use absolute torque or absolute strain as the basis for judgment, but use the no-load reference as the reference, which can reduce the influence of equipment installation deviation, initial bearing friction and temperature micro-change on the judgment result.

[0021] The real-time material flowability assessment module includes: a net propulsion torque calculation subunit, used to determine the net propulsion torque based on the current output torque and the no-load output torque; The characteristic deformation rate extraction subunit is used to extract the characteristic deformation rate based on the comprehensive characteristic deformation response of the four strain gauge units 14, which is the current micro-strain value and the unloaded micro-strain value. The dynamic liquidity index calculation subunit is used to determine the dynamic liquidity index based on net propulsion torque and characteristic deformation rate. During continuous conveying, the control system synchronously reads the current output torque of the servo motor 5 and the current micro-strain values ​​of the four strain gauge units 14, and compares them with the no-load reference respectively; the net propulsion torque is obtained by subtracting the no-load output torque from the current output torque, which reflects the actual propulsion load of the screw shaft 4 on the material; the deformation rate is obtained by differentiating the four deformations with respect to time, and the maximum value is selected as the characteristic deformation rate, which is used to characterize the position where the pressure response intensity of the pipe wall is the greatest; Based on this, the dynamic flowability index calculation subunit receives the net propulsion torque and characteristic deformation rate and performs calculations to identify the flow state of the material inside the pipe; wherein, the net propulsion torque characterizes the rotational torque applied by the screw shaft 4 to overcome the resistance of material movement, and the characteristic deformation rate characterizes the gradient of the radial compressive stress of the material on the pipe wall; the dynamic flowability index calculation subunit outputs the dynamic flowability index by dividing the net propulsion torque by the characteristic deformation rate; When the index is high, it indicates that the energy is mainly used for axial propulsion and the material is in a continuous flow state; when the index decreases, it indicates that the material accumulates and compacts towards the pipe wall when pushed, and the energy is converted into radial extrusion deformation, which serves as the basis for judging mild agglomeration and severe bridging. The processing flow of the real-time material flowability assessment module is executed in the following order: Step 1, collect the output torque value of the servo motor 5 in the current sampling period, and the micro-strain value of the four strain gauge units 14 in the same sampling period. Step 2: Subtract the corresponding unloaded micro-strain value from the four current micro-strain values ​​to obtain four deformation values, in order to eliminate the fixed background amount caused by installation pre-tightening, pipe body self-weight and temperature drift; Step 3: For each deformation, the corresponding deformation rate is obtained by dividing the difference between two adjacent sampling periods by the sampling time interval, thereby reflecting the rate of change of pressure on the pipe wall at that location. Step 4: Select the one with the largest value among the four deformation rates as the characteristic deformation rate, which means the response intensity of the location with the most drastic pressure change within the main conveying section 10 at the current moment. Step 5: Subtract the no-load output torque from the current output torque to obtain the net propulsion torque. Then, process the net propulsion torque with the characteristic deformation rate to obtain the dynamic flow index for use by the state control module. The reason why the characteristic deformation rate is taken as the maximum value among the four deformation rates is that agglomeration and bridging usually form locally first. If the average value is used, the local abnormal signal is easily smoothed by the average value calculation, while taking the maximum value can reflect the concentrated stress change on the pipe wall caused by local accumulation earlier. To ensure the stability of the calculation results, the control system preferably performs time alignment on the torque signal and the micro-strain signal first. That is, the encoder of the servo motor 5 and the amplifier of the strain gauge 6 are triggered by the same hardware clock of the control system to perform strict synchronous sampling. The spike interference of a single sampling point is smoothed by a moving average filtering algorithm or a Kalman filtering algorithm before the above differential calculation is performed. When the characteristic deformation rate is close to zero, the control system does not directly perform division. Instead, it first determines the state as insufficient deformation response and maintains the dynamic fluidity index of the previous effective cycle. Alternatively, it substitutes the preset minimum effective deformation rate lower limit into the calculation. The minimum effective deformation rate lower limit is greater than the background noise of the strain gauge 6 system and is determined based on the fluctuation variance of the micro-strain value during the system's no-load steady-state operation to avoid abnormal amplification of the index due to an excessively small denominator. The dynamic fluidity index output by this process is transmitted to the mild agglomeration judgment unit and the severe bridging judgment unit as the direct judgment input for subsequent selection of pulsating resonance processing or reversal reshaping processing. To further clarify the programmable implementation process of this algorithm, a quantitative derivation example is provided: Assume that the no-load output torque of the servo motor 5 is 0.2 N·m, and the no-load micro-strain value is 10 με; within a certain sampling period, the current output torque is 3.2 N·m, the current micro-strain values ​​of the four strain gauge units 14 are 12, 15, 30, and 11 με, respectively, the sampling time interval is 0.1 s, and the deformation of the previous period is 1, 4, 15, and 0 με, respectively; The system calculates the net propulsion torque as 3.2 - 0.2 = 3.0 N·m; the deformation at the four positions is calculated as 2, 5, 20, and 1 με, respectively. The difference between these values ​​and the previous cycle is calculated and divided by 0.1 s to obtain deformation rates of 10, 10, 50, and 10 με / s, respectively; the system extracts the maximum value of 50 με / s as the characteristic deformation rate. The dynamic liquidity index is calculated as 3.0 / 50 = 0.06. If the calculated characteristic deformation rate is less than the minimum effective deformation rate lower limit, the system will force the characteristic deformation rate to be assigned to the preset minimum effective deformation rate lower limit for division. This operation logic is based entirely on basic arithmetic and logical judgment, the data flow is clear, no complex function calls are required, and ordinary programmable logic controllers can meet the real-time requirements.

[0022] The high-frequency pulsating resonance unit includes: a resonance frequency conversion sub-unit, used to extract the matching pulsating frequency based on the structural parameters of the wavy notch 8 on the spiral blade 7 and the basic rotational speed of the spiral shaft 4; The waveform superposition subunit is used to superimpose a sinusoidal speed fluctuation with a fluctuating frequency on the original base speed, so that the period of the speed fluctuation coincides with the period of the wave-shaped notch 8 sweeping over a specific agglomerated area of ​​the pipe wall. When the dynamic flowability index is between the first and second thresholds, the control system determines that the material has slightly agglomerated and converts the notch spacing of the spiral blade 7 with the current rotation speed into the corresponding fluctuation frequency. This fluctuation frequency is written into the speed command of the servo driver, and a sinusoidal speed disturbance is superimposed on the base rotation speed, so that the notch forms a periodic shearing and squeezing effect when passing through the agglomerated area. Since the fluctuation period is consistent with the period of the notch passing through the local area, the local adhesion layer inside the pipe is more likely to detach from the pipe wall and re-enter the main material flow under alternating force, thereby reducing the probability of the slight agglomeration continuing to develop. The inputs to the resonant frequency conversion subunit include the current base rotational speed, the peak-to-valley distance between adjacent wavy notches 8 on the outer edge of the helical blade 7, and the number of effective notch repetitions on the outer edge of the helical blade 7 around one circumference. The control system first determines the linear velocity of the circumference where the notch is located based on the outer diameter of the helical blade 7, and then determines how many notch repetitions will sweep across the same local area per unit time based on the peak-to-valley distance, thereby obtaining the target frequency of the rotational speed fluctuation. The conversion relationship can be expressed as: In the formula, the physical unit of the fluctuation frequency is Hz; the physical unit of the linear velocity of the outer edge of the helical blade is m / s; the gap spacing in the formula is the peak-valley spacing of the gap, which refers to the arc length spacing between adjacent wavy gaps, and the physical unit is m; for the structural dimensions given in this embodiment, the control system can also first calculate the number of revolutions per second of the helical shaft 4 from the current rotation speed, and then combine the effective gap repetition number corresponding to each revolution to obtain the same target frequency; the execution order of the waveform superposition subunit is as follows: first read the current base rotation speed as the center rotation speed, then output the target fluctuation frequency from the resonance frequency conversion subunit, then generate a sinusoidal speed disturbance command according to the frequency, and superimpose it on the base rotation speed to form the instantaneous speed setpoint of the servo motor 5; The resonance here does not refer to the structural components of the equipment entering a dangerous mechanical resonance, but rather to the speed disturbance period matching the action period of the gap passing over the local agglomeration area, making the local material easier to loosen under repeated shearing and squeezing. In order to avoid the disturbance amplitude being too large and causing drastic fluctuations in the conveying volume, the control system preferably limits the amplitude of the sinusoidal speed fluctuation within a preset ratio range of the base speed, and releases the waveform superposition control after the dynamic flowability index rises above the first threshold, restoring the base speed operation. Example

[0023] The reverse reshaping compensation unit includes: a reverse bridge breaking subunit, which controls the servo motor 5 to decelerate to a stop within 0.5s and then reverse at a speed of 30r / min for 2s, so that the spiral blades 7 can reverse the material of the bridging part towards the feed inlet 12 for reverse conveying and peeling. The forward rotation recovery subunit is used to control the servo motor 5 to resume forward rotation after the reverse rotation ends, and to accelerate to the base speed at an acceleration of 5r / s². The flow compensation calculation subunit is used to calculate the transport volume deficit and speed compensation increment after the bridging is eliminated and the dynamic flow index recovers to above the first threshold. The compensation operation subunit is used to control the servo motor 5 to operate with speed compensation increments on top of the base speed until the material conveying of the current batch is completed. When the dynamic flow index falls below the second threshold, the control system determines the state as severe bridging and issues a control command to the servo motor 5 to rapidly decelerate to a stop, causing the spiral shaft 4 to stop operating within 0.5 seconds. The motor then reverses at 30 r / min for 2 seconds, using the spiral blades 7 to reverse the conveying and stripping of the bridging area, causing the material to lose its original support structure. After the reversal, the motor resumes forward rotation and increases back to the base speed at 5 r / s² to avoid secondary accumulation caused by sudden load changes. The system then calculates the speed compensation increment based on the conveying loss during the stop and reversal periods, and adds this increment during the remaining conveying time to ensure that the conveying volume of the current batch of material is consistent with the process requirements.

[0024] The flow compensation calculation subunit is used to: obtain the time value of the deceleration, reversal and resumption of forward rotation lifting process; extract the conveying volume deficit value based on the time value, and determine the speed compensation increment in combination with the remaining planned conveying time of the current batch of materials; After the reversal process is completed and forward rotation resumes, the control system calculates the time spent in the three stages of deceleration, reversal, and slow acceleration, and integrates the actual rotational speed during this time period to obtain the theoretically uncompleted conveying volume deficit during this period. In this process, the flow compensation calculation subunit essentially constitutes a closed-loop flow recovery model. The purpose of this model is to accurately compensate for the material conveying gap caused by shutdown and reversal after handling bridging failure, and to ensure the stability of single-batch output. In terms of logical structure and data flow, the model receives the time consumed by the deceleration, reversal, and slow acceleration processes, as well as the actual rotation speed during that time period, as inputs. By integrating the rotation speed over time, it calculates the theoretically uncompleted transport volume deficit. The model further receives the remaining planned conveying time, divides the conveying deficit by the remaining time, and outputs the speed compensation increment. In terms of the physical relationship represented, the model abstracts the linear proportional mapping relationship between the speed and the volumetric flow rate of the screw conveyor. Because the volume loss is quantified by the time integral of the speed, the macroscopic flow deficit can be transformed into a microscopic speed compensation command. The compensation value, superimposed on the base speed, is used for subsequent operation, enabling precise quantification and replenishment of flow loss during the recovery process. Ultimately, because the speed is compensated, fluctuations in material received by downstream equipment are eliminated. To ensure the programmable implementation of this software module, its specific calculation logic is executed according to the following data flow steps: An accumulation register is set up inside the system. During deceleration, reversal, and slow acceleration, the difference between the current actual speed and the base speed is read at a fixed sampling period. This difference is multiplied by the sampling period and accumulated to obtain the total speed integral deficit. The system reads the remaining planned delivery time for the current batch of materials. The total speed integral deficit is divided by the remaining planned delivery time to obtain the speed compensation increment. If the base speed is 1 r / s, the total time for the system to handle the bridge failure is 2.7s, which is the total time for deceleration, reversal, and acceleration recovery. If the system should rotate 2.7 r at the base speed within these 2.7s, but the actual number of rotations is -0.65 r obtained through discrete integration, the total speed integral deficit is 2.7 - (-0.65) = 3.35 r. If the remaining planned delivery time is 55s, the speed compensation increment is 3.35 / 55 ≈ 0.06 r / s. The control system updates the running command of servo motor 5 to 1.06 r / s until the delivery ends. Through the above calculations, the flow deficit is quantified and regressed, ensuring the accurate output of the control logic.

[0025] The total length of the conveying pipe 3 is 3m and the inner diameter is 200mm; the length of the main conveying section 10 is 2m and the spacing between adjacent strain gauge units 14 is 0.5m. With the total length of the conveying pipe 3 set to 3m and the inner diameter set to 200mm, it can provide a conveying volume that meets the design capacity requirements for p-aminobenzenesulfonic acid powder, while avoiding uneven material spreading caused by excessively large pipe diameter. The main conveying section 10 is 2m long, which facilitates the arrangement of four strain gauge units 14 in the stable conveying area. The spacing between adjacent strain gauge units 14 is 0.5m, so that the sensor can cover the main stress distribution area of ​​the main conveying section 10. This size configuration matches the calculation position of the dynamic flowability index, so that the changes in pipe wall pressure caused by local agglomeration can be captured in time.

[0026] The main body of the spiral shaft 4 is made of seamless steel pipe 16 with an outer diameter of 60mm and a wall thickness of 10mm; the outer diameter of the spiral blade 7 is 190mm, and it forms a radial gap of 5mm with the inner wall of the conveying pipe 3; the pitch of the spiral blade 7 is set to 150mm; the depth of the wavy notch 8 is 5mm, and the peak-valley spacing between adjacent notches is 20mm. The main body of the spiral shaft 4 is made of seamless steel pipe 16 with an outer diameter of 60mm and a wall thickness of 10mm. This can reduce the moment of inertia while ensuring torsional rigidity, making it suitable for speed fluctuation control of servo motor 5. After the outer diameter of the spiral blade 7 is set to 190mm, a radial gap of 5mm is formed with the inner wall of the conveying pipe 3, which can reduce the risk of jamming while maintaining effective propulsion of powder. When the pitch is 150mm, the axial displacement of the material is stable during each revolution, which is convenient for coordination with the periodic action of the wavy notch 8. The wavy notch 8 is set with a depth of 5mm and a peak-to-valley spacing of 20mm, which allows the notch to form repeatable local shearing and disturbance when passing through the material agglomeration area, making it suitable for use with high-frequency pulse control.

[0027] Combination Figure 3 As shown, the two ends of the spiral shaft 4 pass through the end caps 17 of the conveying pipe 3 and are supported by the first bearing seat 18 and the second bearing seat 19. The first bearing seat 18 and the second bearing seat 19 are both fixedly connected to the base 2 and are located 0.2m outside the two ends of the conveying pipe 3 respectively. The first bearing seat 18 adopts a structure combining a labyrinth seal 20 and a lip seal 21 to isolate dust. After the two ends of the spiral shaft 4 pass through the end caps 17 of the conveying pipe 3, they are supported by the first bearing seat 18 and the second bearing seat 19 located 0.2m outside the two ends of the conveying pipe 3. The bearing seats are fixed on the base 2, which can make the stress point of the shaft system separate from the powder area inside the conveying pipe 3, reducing the probability of dust entering the bearing. The first bearing seat 18 adopts a combination structure of labyrinth seal 20 and lip seal 21. The labyrinth seal 20 is used to form multi-level path barrier, and the lip seal 21 is used to further isolate fine dust, thereby reducing bearing grease contamination and wear. When this structure is combined with the external support method, it can maintain the stable rotation of the spiral shaft 4 without damaging the airtightness of the pipe body and improve the mechanical reliability under long-term operation.

[0028] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A powder conveyor for the production of p-aminobenzenesulfonic acid, characterized in that, include: The powder conveying execution module (1) includes a base (2), a conveying pipe (3) fixed above it, a spiral shaft (4) coaxially inserted in the conveying pipe (3), a servo motor (5) driving the spiral shaft (4), and a strain gauge (6) attached to the outer wall of the conveying pipe (3) along the axial direction. The outer wall of the spiral shaft (4) is provided with continuous spiral blades (7), and its outer edge is machined with continuous wavy notches (8). The resistance reference calibration module is used to control the servo motor (5) to rotate at a steady speed when unloaded, and to record its unloaded output torque and the unloaded micro-strain value of the strain gauge (6). The material flowability real-time assessment module is used to control the motor (5) to run at a preset base speed during normal conveying, and to collect its current output torque and current micro-strain value to calculate the dynamic flowability index. The adaptive state control module, based on the dynamic liquidity index, performs resonance-based arch breaking or reversal reshaping and compensation control on the execution module (1), including: The mild clumping determination unit is used to determine mild clumping when the dynamic liquidity index is less than a preset first threshold and greater than or equal to a preset second threshold. The high-frequency pulsating resonance unit is used to control the motor (5) to enter the high-frequency pulsating mode and superimpose a sinusoidal wave on the base speed when it is determined that there is slight agglomeration. The severe bridging determination unit is used to determine severe bridging when the dynamic liquidity index is less than a preset second threshold. The reversing reshaping compensation unit is used to control the motor (5) to decelerate, reverse, and resume forward rotation in sequence when a severe bridge is detected, and to perform speed compensation incremental operation.

2. The powder conveyor for the production of p-aminobenzenesulfonic acid according to claim 1, characterized in that, The conveying pipe (3) is divided into a feeding section (9), a main conveying section (10) and a discharging section (11). The feeding section (9) has a feeding port (12) above it and a discharging port (13) below it. The wall thickness of the main conveying section (10) is set to 3 mm. The strain gauge (6) includes four strain gauge units (14) that are equidistantly pasted along the outer wall of the main conveying section (10). The strain gauge units (14) are covered with an epoxy resin protective layer (15).

3. The powder conveyor for the production of p-aminobenzenesulfonic acid according to claim 2, characterized in that, The resistance reference calibration module is used to: control the servo motor (5) to drive the spiral shaft (4) to rotate continuously at a stable speed of 50r / min for 3 minutes when there is no material entering the feed inlet (12) under no-load conditions; The no-load output torque of the servo motor (5) at the specified speed is recorded in real time, and the no-load micro-strain value output by the four strain gauge units (14) is also recorded. The no-load output torque and the no-load micro-strain value are stored as reference parameters in the resistance reference calibration module.

4. The powder conveyor for the production of p-aminobenzenesulfonic acid according to claim 3, characterized in that, The real-time material flowability assessment module includes: A net propulsion torque calculation subunit is used to determine the net propulsion torque based on the current output torque and the no-load output torque. The characteristic deformation rate extraction subunit is used to extract the characteristic deformation rate based on the comprehensive characteristic deformation response of the current micro-strain value and the unloaded micro-strain value of the four strain gauge units (14); The dynamic liquidity index calculation subunit is used to determine the dynamic liquidity index based on the net propulsion torque and the characteristic deformation rate.

5. The powder conveyor for the production of p-aminobenzenesulfonic acid according to claim 4, characterized in that, The high-frequency pulsating resonance unit includes: a resonance frequency conversion subunit, used to extract the matching pulsating frequency based on the structural parameters of the wavy notch (8) on the spiral blade (7) and the basic rotation speed of the spiral shaft (4); The waveform superposition subunit is used to superimpose the sinusoidal rotational speed fluctuation with the fluctuation frequency on the original base rotational speed, so that the period of the rotational speed fluctuation coincides with the period of the wave-shaped gap (8) sweeping across a specific agglomerated area of ​​the pipe wall.

6. The powder conveyor for the production of p-aminobenzenesulfonic acid according to claim 5, characterized in that, The reverse reshaping compensation unit includes: a reverse bridge breaking subunit, which controls the servo motor (5) to decelerate to a stop within 0.5s and then reverse at a speed of 30r / min for 2s so that the spiral blades (7) convey and peel off the material at the bridging part in the opposite direction to the feed inlet (12). The forward rotation recovery subunit is used to control the servo motor (5) to resume forward rotation after the reverse rotation ends, and to accelerate to the base speed at an acceleration of 5r / s². The flow compensation calculation subunit is used to calculate the delivery deficit and speed compensation increment after the bridging is eliminated and the dynamic flow index recovers to above the first threshold. The compensation operation subunit is used to control the servo motor (5) to operate by superimposing the speed compensation increment on the base speed until the material conveying of the current batch is completed.

7. The powder conveyor for the production of p-aminobenzenesulfonic acid according to claim 6, characterized in that, The flow compensation calculation subunit is used to: obtain the time values ​​consumed during the deceleration, reversal, and recovery forward rotation lifting processes; Based on the time consumed, the conveying volume deficit is extracted, and combined with the remaining planned conveying time of the current batch of materials, the speed compensation increment is determined.

8. The powder conveyor for the production of p-aminobenzenesulfonic acid according to claim 7, characterized in that, The total length of the conveying pipe (3) is 3m and the inner diameter is 200mm; the length of the main conveying section (10) is 2m and the spacing between adjacent strain gauge units (14) is 0.5m.

9. The powder conveyor for the production of p-aminobenzenesulfonic acid according to claim 8, characterized in that, The main body of the spiral shaft (4) is made of a seamless steel pipe (16) with an outer diameter of 60 mm and a wall thickness of 10 mm; the outer diameter of the spiral blade (7) is 190 mm, and it forms a radial gap of 5 mm with the inner wall of the conveying pipe (3); the pitch of the spiral blade (7) is set to 150 mm; the depth of the wavy notch (8) is 5 mm, and the peak-to-valley distance between adjacent notches is 20 mm.

10. The powder conveyor for the production of p-aminobenzenesulfonic acid according to claim 9, characterized in that, The two ends of the spiral shaft (4) pass through the end caps (17) of the conveying pipe (3) respectively, and are supported by the first bearing seat (18) and the second bearing seat (19); the first bearing seat (18) and the second bearing seat (19) are both fixedly connected to the base (2) and are located 0.2m outside the two ends of the conveying pipe (3) respectively; the first bearing seat (18) adopts a structure combining a labyrinth seal (20) and a lip seal (21) to isolate dust.

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