Potassium nitrate crystallization homogenization stirring method and device

Abstract

The application discloses a potassium nitrate crystallization homogenization stirring method and device, relates to the technical field of industrial crystallization and chemical process equipment control, and comprises the following steps: setting an inner circulation lifting area, an outer circulation reflux area and a near-wall reflux area in a crystallization container; adjusting the switching position of a flow path switching sleeve, changing the connection sequence of the crystallization slurry among the inner circulation lifting area, the outer circulation reflux area and the near-wall reflux area, and performing potassium nitrate crystallization homogenization stirring. The method has good effects in terms of crystallization slurry uniformity, controllability of the crystallization process and stability of equipment operation.

Description

Technical Field

[0001] This invention relates to the field of industrial crystallization and chemical process equipment control technology, specifically to a method and apparatus for homogenizing and stirring potassium nitrate crystals. Background Technology

[0002] Existing crystallization stirring equipment mostly uses a pre-set fixed speed or fixed operating cycle, making it difficult to adjust the stirring mode in a timely manner according to the state of the crystal slurry in different areas of the crystallization container.

[0003] Even if some equipment is equipped with detection elements such as temperature, density, turbidity or motor current, the detection results are usually only used to adjust the stirring speed, feed rate or crystallization temperature. They cannot selectively adjust the crystal slurry circulation path for different states such as bottom rich crystals, near-wall rich crystals, and local circulation short circuits.

[0004] In a crystalline slurry environment, the flow path regulating components may also experience positional deviations, increased motion resistance, or clamping due to crystals entering the mating gaps.

[0005] If the flow path regulating component is not accurately positioned before the stirring component is activated, it may cause adjacent flow paths to connect simultaneously, resulting in disordered flow direction or local blockage.

[0006] Existing equipment lacks sufficient judgment on the correlation between flow path position, stirring load and clamping state, and also lacks control measures to first isolate the flow path and automatically reset it under abnormal conditions. Summary of the Invention

[0007] In view of the above-mentioned problems, the present invention is proposed.

[0008] Therefore, the technical problem solved by this invention is that the existing potassium nitrate crystallization stirring method uses a fixed circulation flow path, which easily leads to crystal deposition at the bottom of the crystallization container, enrichment of crystal slurry in the near-wall area, and local circulation short circuits. The degree of crystal slurry homogenization and the reliability of flow path switching are low. The problem is how to orderly switch different circulation flow paths according to the crystal slurry state and realize automatic reset of abnormal clamping.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for homogenizing and stirring potassium nitrate crystals, comprising setting up an internal circulation lifting zone, an external circulation reflux zone and a near-wall reflux zone in a crystallization container.

[0010] Adjust the switching position of the flow path switching sleeve to change the connection sequence of the crystal slurry between the internal circulation lifting zone, the external circulation reflux zone, and the near-wall reflux zone, and carry out potassium nitrate crystallization homogenization stirring.

[0011] The switching positions of the flow path switching sleeve include a first switching position, a second switching position, and a third switching position.

[0012] The homogenization stirring includes axial lifting, radial reflux, near-wall scraping, and reflow lifting of the crystal slurry in sequence during the crystallization process.

[0013] As a preferred embodiment of the potassium nitrate crystallization homogenization stirring method of the present invention, the first switching position includes, in the first switching position, the inner circulation lifting zone and the outer circulation reflux zone are connected through the first window group, and the crystal slurry at the bottom of the crystallization container is sent into the inner circulation lifting zone through the lower lifting stirring member.

[0014] The second switching position includes the following: in the second switching position, the external circulation reflux zone and the near-wall reflux zone are connected through the second window group, and the rich crystal slurry on the inner wall side of the crystallization container is sent into the external circulation reflux zone by the scraping reflux component.

[0015] The third switching position includes a third window group connecting the near-wall reflux zone and the internal circulation lifting zone, where the rich crystal slurry from the near-wall reflux zone and the crystal slurry from the bottom of the crystallization container are combined in the suction area of ​​the lower lifting stirring component.

[0016] In a preferred embodiment of the potassium nitrate crystallization homogenization stirring method of the present invention, crystal slurry state data and execution state data are collected before or during the adjustment of the flow path switching sleeve.

[0017] The slurry state data includes at least two of the following: temperature, density, turbidity, and particle size characterization values ​​within the crystallization container.

[0018] The execution status data includes at least two of the following: the driving current of the lower lifting and stirring component, the stirring torque, the load value of the scraping and returning component, and the position feedback value of the flow path switching sleeve.

[0019] A crystallization homogenization state characterization quantity is generated based on the slurry state data and the execution state data.

[0020] As a preferred embodiment of the potassium nitrate crystallization homogenization stirring method of the present invention, wherein: bottom rich crystal characterization, near-wall rich crystal characterization and cyclic short-circuit characterization are generated according to the crystallization homogenization state characterization values ​​respectively.

[0021] The bottom rich crystal characterization, near-wall rich crystal characterization, and cycle short-circuit characterization are matched with the preset switching threshold to generate the flow path switching state.

[0022] The flow path switching states include a lifting and recirculation state corresponding to the first switching position, a near-wall scraping state corresponding to the second switching position, a return and lifting state corresponding to the third switching position, and an intermediate closed state located between adjacent switching positions.

[0023] As a preferred embodiment of the potassium nitrate crystallization homogenization stirring method of the present invention, the flow path switching state includes generating a target switching position of the flow path switching sleeve according to the flow path switching state.

[0024] When the flow path switching sleeve moves from the current switching position to the target switching position, the flow path switching sleeve first enters the intermediate closed state and then enters the target switching position.

[0025] When the position feedback value of the flow path switching sleeve matches the alignment condition of the window group corresponding to the target switching position, a stirring execution command corresponding to the target switching position is generated.

[0026] As a preferred embodiment of the potassium nitrate crystallization homogenization stirring method of the present invention, the stirring execution command includes the residence time of the flow path switching sleeve, the rotation speed of the lower lifting stirring component, the scraping speed of the scraping return component, and the switching waiting time.

[0027] In the first switching position, the stirring execution command includes the lifting speed of the lower lifting stirring component.

[0028] In the second switching position, the stirring execution command includes the scraping speed of the scraping return member.

[0029] The stirring execution command in the third switching position includes the synchronous execution time of the lower lifting stirring component and the scraping return component.

[0030] As a preferred embodiment of the potassium nitrate crystallization homogenization stirring method of the present invention, after completing a switching cycle consisting of a first switching position, a second switching position, and a third switching position, crystal slurry state data and execution state data are collected, and the crystallization homogenization state characterization quantity is updated based on the collected data.

[0031] When the difference between the updated crystallization homogenization state characterization value and the crystallization homogenization state characterization value corresponding to the previous switching cycle falls into the preset correction range, the residence time of at least one switching position or at least one stirring execution command in the next switching cycle is adjusted.

[0032] As a preferred embodiment of the potassium nitrate crystallization homogenization stirring method of the present invention, wherein: when the position feedback value of the flow path switching sleeve does not meet the window group alignment condition, the correspondence between the driving current and stirring torque of the lower lifting stirring component falls into the preset clamping judgment range, the flow path switching sleeve is kept in the middle closed state, and a reset switching command is generated.

[0033] The reset switching command includes the reverse micro-motion angle of the flow path switching sleeve, the reset waiting time, and the target switching position after reset.

[0034] Another objective of this invention is to provide a potassium nitrate crystallization homogenization stirring device, which can selectively connect the inner circulation lifting zone, the outer circulation reflux zone, and the near-wall reflux zone in a predetermined order by setting a flow path switching sleeve with multiple switching positions. This solves the problems of bottom crystal deposition, near-wall crystal slurry enrichment, local circulation short circuits, and insufficient reliability of flow path switching caused by the use of fixed circulation flow paths in existing crystallization stirring equipment.

[0035] As a preferred embodiment of the potassium nitrate crystallization homogenization stirring device of the present invention, it includes a crystallization container, a flow path switching sleeve, a lower lifting stirring component, a scraping and reflux component, a fixed flow guiding component, a switching drive component, a crystallization state acquisition unit, and a control unit.

[0036] The fixed flow guiding component is installed inside the crystallization container and cooperates with the crystallization container to form an internal circulation lifting zone, an external circulation reflux zone, and a near-wall reflux zone.

[0037] The flow path switching sleeve is connected to the switching drive component and is provided with a first window group, a second window group, and a third window group.

[0038] The crystallization state acquisition unit is respectively installed in at least two locations in the crystallization container, the lower lifting and stirring component, the scraping and reflux component, and the flow path switching sleeve.

[0039] The control unit is connected to the crystallization state acquisition unit, the switching drive component, the lower lifting and stirring component, and the scraping and reflux component, respectively.

[0040] As a preferred embodiment of the potassium nitrate crystallization homogenization stirring device of the present invention, the control unit includes a state characterization module, a state switching generation module, an execution instruction generation module, and a feedback correction module.

[0041] The state characterization module is used to generate a crystallization homogenization state characterization quantity based on the data collected by the crystallization state acquisition unit. The switching state generation module is used to generate flow path switching states based on the crystallization homogenization state characterization parameters.

[0042] The execution command generation module is used to generate execution commands for the flow path switching sleeve, the lower lifting and stirring component, and the scraping and returning component based on the flow path switching status.

[0043] The feedback correction module is used to correct the execution command for the next switching cycle based on the position feedback value of the flow path switching sleeve and the execution status data.

[0044] The beneficial effects of this invention are as follows: The potassium nitrate crystallization homogenization stirring method provided by this invention uses a flow path switching sleeve that moves between different switching positions, sequentially connecting the inner circulation lifting zone, the outer circulation reflux zone, and the near-wall reflux zone. This achieves bottom crystal slurry lifting, near-wall rich crystal slurry scraping, and rich crystal slurry return, reducing bottom deposition, near-wall enrichment, and circulation short circuits caused by a fixed circulation flow path. By collecting data such as temperature, density, turbidity, particle size, and applied load, a crystallization homogenization state characterization quantity is generated, allowing adjustment of the switching position and stirring parameters according to the crystal slurry state. Through intermediate closure, position alignment, feedback correction, and clamping reset mechanisms, the accuracy of flow path switching and operational reliability are improved. This invention has excellent effects on crystal slurry uniformity, crystallization process controllability, and equipment operational stability. Attached Figure Description

[0045] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a schematic diagram of the three flow zones and basic homogenization stirring in a crystallization container for a potassium nitrate crystallization homogenization stirring method provided in Embodiment 1 of the present invention.

[0047] Figure 2 This is a schematic diagram of the window group connection state under three switching positions in a potassium nitrate crystallization homogenization stirring method provided in Embodiment 2 of the present invention.

[0048] Figure 3 This is a schematic diagram of a flow path switching method based on state characterization parameters for a potassium nitrate crystallization homogenization stirring method provided in Embodiment 3 of the present invention.

[0049] Figure 4 This is a structural diagram of an apparatus for a potassium nitrate crystallization homogenization stirring method provided in Embodiment 4 of the present invention. Detailed Implementation

[0050] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. 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 protection scope of the present invention.

[0051] Example 1: Refer to Figure 1As an embodiment of the present invention, a timed sequential switching type of potassium nitrate crystallization homogenization stirring method is provided, specifically including: The crystallization container 100 is pre-formed with an internal circulation lifting zone 101, an external circulation reflux zone 102, and a near-wall reflux zone 103. The flow path switching sleeve 200 has a first switching position 201, a second switching position 202, and a third switching position 203.

[0052] In this embodiment, potassium nitrate mother liquor is first added to the crystallization container 100 to allow the mother liquor to enter the cooling crystallization or evaporation crystallization stage.

[0053] The initial rotation speed of the lower lifting and stirring component 300 is set to 120 rpm, and the initial rotation speed of the scraping and reflux component 400 is set to 20 rpm.

[0054] Each switching cycle of the flow path switching kit 200 includes a stay of 60s at the first switching position 201, a stay of 45s at the second switching position 202, and a stay of 90s at the third switching position 203.

[0055] It should be noted that the residence time can be set from 30s to 180s depending on the volume of the crystallization container.

[0056] The flow path switching sleeve 200 is brought to the first switching position 201, the first window group is opened, and the inner circulation boosting area 101 is connected to the outer circulation return area 102.

[0057] Start the lower lifting and stirring component 300 to draw the crystal slurry from the bottom of the crystallization container 100 into the suction area 301 and lift it upward along the inner circulation lifting area 101.

[0058] The lifted slurry enters the external circulation reflux zone 102 through the first window group and refluxes along the outside of the crystallization container 100.

[0059] The flow path switching sleeve 200 is moved to the second switching position 202, the second window group is opened, and the external circulation return area 102 is connected to the near-wall return area 103.

[0060] Start the scraping and reflux component 400 to scrape the rich crystal slurry adhering to or near the inner wall of the crystallization container 100 into the near-wall reflux zone 103.

[0061] The flow path switching sleeve 200 is moved to the third switching position 203, the third window group is opened, and the near-wall reflux zone 103 is connected to the internal circulation enhancement zone 101.

[0062] The rich crystal slurry in the near-wall reflux zone 103 is fed back to the suction zone 301 of the lower lifting stirring member 300 and merges with the crystal slurry at the bottom of the crystallization container 100.

[0063] Repeat until the crystallization batch reaches the discharge condition. If the flow path switching sleeve 200 is not in position at any switching position, control it to return to the intermediate closed state between adjacent switching positions and pause the opening action of the next window group.

[0064] Example 2: Refer to Figure 2 As an embodiment of the present invention, an embodiment of flow path switching control based on crystallization state characterization parameters is provided in a potassium nitrate crystallization homogenization stirring method, specifically including: Density detector, turbidity detector, particle size characterization detector, current detector and torque detector are installed on the crystallization container 100.

[0065] Density measuring devices collected the density at the bottom of the crystallization container 100. and central density The turbidity measuring device collected 103 turbidity samples from the near-wall reflux zone. Turbidity in the middle of crystallization container 100 The particle size characterization test specimen collected 103 particle size characterization values ​​in the near-wall reflux zone. and the particle size characterization value in the middle The current detection device collects the driving current I of the lower lifting and stirring component 300, and the torque detection device collects the stirring torque M.

[0066] Before formal crystallization, a calibration process is performed, which includes calibration with clean water under no-load conditions, calibration with potassium nitrate mother liquor, calibration with low solids content crystal slurry, and calibration with target solids content crystal slurry.

[0067] The reference drive current was determined based on the calibration using clean water under no-load and potassium nitrate mother liquor. and reference stirring torque .

[0068] The preset bottom crystal-rich threshold θb and the preset near-wall crystal-rich threshold θw are determined based on the calibration of low solids content slurry and the calibration of target solids content slurry.

[0069] The solid content of low-solids crystalline slurry can be 20% to 50% of the target solid content, and the solid content of the target solids crystalline slurry is set according to the requirements of the discharge process.

[0070] The calibration data table includes the calibration batch number, switching location, sampling time, and , , , , , I and M.

[0071] During the crystallization process, data were collected every 5 to 60 seconds, and the bottom rich crystal characterization and near-wall rich crystal characterization were calculated.

[0072] A preferred method for calculating the characterization of bottom-rich crystals is as follows:

[0073] in, This indicates the amount of crystal-rich material at the bottom. Indicates the density at the bottom. This indicates the mid-density, and M represents the stirring torque. Indicates the reference stirring torque, and I represents the drive current. Indicates the reference drive current. These represent three different weighting coefficients.

[0074] The contribution of data fluctuations in each batch of the target solid content slurry to the slurry enrichment state is determined.

[0075] Specifically, after completing the calibration of the target solid crystal slurry, density change, torque change and current change are taken as three candidate influencing factors, and the trend of the bottom crystal enrichment degree in the calibration batch is used as a reference.

[0076] Based on the synchronization of candidate influence terms with the enrichment level of the bottom crystal, weights are assigned to candidate influence terms, and this ensures... .

[0077] The Eb parameter determines whether to enter the first switching position 201 or the third switching position 203.

[0078] A preferred method for calculating the near-wall rich crystal characterization is as follows:

[0079] in, This indicates the near-wall rich crystal characterization quantity. Indicates the turbidity in the near-wall reflux region. This indicates the turbidity in the middle of the crystallization container. This represents the particle size characterization value of the near-wall recirculation zone. This represents the particle size characterization value in the middle section. These represent two different weighting coefficients, and .

[0080] Used to determine whether to enter the second switching position 202 or the third switching position 203, with a preset bottom rich crystal threshold. and preset near-wall rich crystal threshold Generated from the calibration data table.

[0081] In the target solid crystal slurry calibration batch The average value of the stable segment is denoted as The standard deviation is denoted as .

[0082] Will The average value of the stable segment is denoted as The standard deviation is denoted as The stable segment is the interval in which the fluctuation of the sampled data is less than the set fluctuation range for 3 to 10 consecutive sampling cycles after the flow path switching sleeve 200 enters the corresponding switching position.

[0083] A preferred method for calculating the preset threshold is:

[0084] in, , This represents the threshold coefficient, which can range from 1 to 3. This indicates the preset bottom crystal-rich threshold region. This indicates a preset near-wall rich crystal threshold region. This represents the average value of the stable segment of the bottom rich crystal characterization quantity. This represents the average value of the stable segment of the near-wall rich crystal characterization quantity. This indicates the standard deviation of the bottom rich crystal characterization quantity. This represents the standard deviation of the near-wall rich crystal characterization.

[0085] and Write the flow path switching judgment table; the judgment table includes three fields: judgment condition, target switching position, and execution action.

[0086] when fall into and Not fallen At this time, the flow path switching sleeve 200 enters the first switching position 201, and the lower lifting stirring component 300 performs a lifting action.

[0087] when fall into and When the flow path switching sleeve 200 does not fall into θb, the flow path switching sleeve 200 is moved to the second switching position 202, and the scraping and feeding return component 400 is made to perform scraping action.

[0088] when and When all fall into the corresponding threshold range, the flow path switching sleeve 200 enters the third switching position 203, and the rich crystal slurry in the near-wall reflux zone 103 enters the suction zone 301.

[0089] like and If none of the data falls within the corresponding threshold range, maintain the current switching position for one sampling period and re-collect the data.

[0090] Example 3: Reference Figure 3As an embodiment of the present invention, a feedback correction and abnormal reset type homogenization stirring method for potassium nitrate crystallization is provided, specifically including: A position detection element is installed on the flow path switching sleeve 200 to output the position feedback value P.

[0091] A current detection element and a torque detection element are installed on the lower lifting and stirring component 300 to output the driving current I and stirring torque M, respectively.

[0092] Before formal operation, the target position value is determined through no-load calibration and mother liquor calibration. Reference drive current and reference stirring torque .

[0093] Before each switch, the flow path switching sleeve 200 is first put into an intermediate closed state between adjacent switching positions, and then enters the target switching position.

[0094] When switching angles, the window group alignment condition is |P﹣Pt|≤0.5° to 3°.

[0095] When switching axially, the window group alignment condition is |P﹣Pt|≤0.5mm to 5mm.

[0096] The alignment conditions for this window group are determined by the window opening width, the sealing edge width, and the resolution of the position detection element.

[0097] Once the position feedback value P meets the window group alignment condition, the execution instruction for the cost switching cycle is generated.

[0098] The execution instructions include: target location change and dwell time. The lower lifting stirring component rotates at a speed of 300. and the rotational speed of the scraping and reflux component 400 .

[0099] The first switching position 201 corresponds to the escalation execution instruction, the second switching position 202 corresponds to the scraping execution instruction, and the third switching position 203 corresponds to the return escalation execution instruction.

[0100] After each switching cycle is completed, the dwell time for the next switching cycle is adjusted based on the change in state.

[0101] A preferred approach to adjusting the dwell time is:

[0102] in, This indicates the dwell time at the j-th switching position in the next switching cycle. This represents the dwell time at the j-th switching position in the current switching cycle. Indicates the shortest stay time. Indicates the longest stay. This represents the correction factor. The value ranges from 0.1 to 0.5. Represents the change in state. and The output is determined by the permissible start / stop frequency of the motor, the volume of the crystallization container, and the batch duration of the process. The dwell time used for the next switching cycle.

[0103] When both the driving current I and the stirring torque M deviate from the reference value, the clamping judgment quantity J is calculated.

[0104]

[0105] Where J represents the pinch-in determination quantity, and I represents the current drive current. M represents the reference drive current, and M represents the current stirring torque. As a reference stirring torque, Let represent the weighting coefficients, and .

[0106] Pinch-off threshold The average value of the stable segment of J in the target solid content slurry calibration batch and standard deviation A preferred method for calculating the pinch-off threshold is as follows:

[0107] in, This indicates the threshold for determining clamping. This represents the average value of the stable segment of J in the calibration batch of the target solid content slurry. This represents the standard deviation of J in the target solid slurry calibration batch.

[0108] when If the sampling continues for 2 to 5 sampling cycles, or if the position feedback value P does not meet the window group alignment condition, the flow path switching sleeve 200 is kept in the middle closed state and a reset action is performed.

[0109] The reset action includes micro-moving in the opposite direction by 1° to 8° or moving in the opposite direction by 1mm to 8mm, and waiting for 1s to 10s before re-entering the target switching position.

[0110] If the window group alignment condition is not met after 2 to 5 consecutive resets, the lower lifting mixing component 300 will run at low speed and a stop check signal will be output.

[0111] Example 4: Reference Figure 4According to one embodiment of the present invention, a potassium nitrate crystallization homogenization stirring device is provided, comprising: a crystallization container 100, a flow path switching sleeve 200, a lower lifting stirring component 300, a scraping and reflux component 400, a fixed flow guiding component 500, a switching drive component 600, a crystallization state acquisition unit 700, and a control unit 800.

[0112] A fixed flow guiding component 500 is disposed inside the crystallization container 100. An inner circulation lifting zone 101 is formed inside the fixed flow guiding component 500, an outer circulation reflux zone 102 is formed between the outer side of the fixed flow guiding component 500 and the crystallization container 100, and a near-wall reflux zone 103 is formed near the inner wall of the crystallization container 100.

[0113] The flow path switching sleeve 200 is rotatably or axially movable and fitted onto the outside of the fixed flow guide member 500. The flow path switching sleeve 200 is provided with a first window group, a second window group, and a third window group. A switching drive member 600 is connected to the flow path switching sleeve 200, and the switching drive member 600 can be a servo motor, a stepper motor, or a pneumatic actuator. A position detection element is mounted on the switching drive member 600 or the flow path switching sleeve 200 and is used to output a position feedback value P.

[0114] A lower lifting and stirring component 300 is disposed at the lower part of the crystallization container 100, including axial lifting blades and a suction area 301. A scraping and reflux component 400 is disposed in the near-wall reflux zone 103, including scraping blades close to the inner wall of the crystallization container 100. The crystallization state acquisition unit 700 includes at least two of the following: a density sensor, a turbidity sensor, a particle size characterization sensor, a current detection device, a torque detection device, and a position detection device.

[0115] The control unit 800 includes a state characterization module 801, a switching state generation module 802, an execution instruction generation module 803, and a feedback correction module 804. The state characterization module 801 receives data from the crystallization state acquisition unit 700 and generates bottom-rich crystal characterization and near-wall-rich crystal characterization.

[0116] The switching state generation module 802 generates a lifting and reflux state, a near-wall scraping and conveying state, a return lifting state, or an intermediate closed state based on the bottom rich crystal characterization value and the near-wall rich crystal characterization value; the execution command generation module 803 generates execution commands for the flow path switching sleeve 200, the lower lifting and stirring component 300, and the scraping and reflux component 400 based on the switching state; the feedback correction module 804 corrects the next cycle command or generates a reset switching command based on the position feedback value P, the drive current I, and the stirring torque M.

[0117] When the device operates independently, the control unit 800 first reads the preset mapping table, then starts the switching drive component 600 to make the flow path switching sleeve 200 move according to the target switching position; then, it judges whether the window group is aligned according to the position feedback value P; after alignment, the control unit 800 drives the lower lifting and stirring component 300 and the scraping and returning component 400 to perform the corresponding actions respectively; after the execution is completed, the feedback correction module 804 reads the data required for the next cycle and updates the execution instructions.

[0118] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution device. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0119] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not 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, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for homogenizing potassium nitrate crystals by stirring, characterized in that, include: An internal circulation lifting zone (101), an external circulation reflux zone (102), and a near-wall reflux zone (103) are provided inside the crystallization container (100). Adjust the switching position of the flow path switching sleeve (200) to change the connection sequence of the crystal slurry between the inner circulation lifting zone (101), the outer circulation reflux zone (102), and the near-wall reflux zone (103) for potassium nitrate crystallization homogenization stirring; wherein, The switching positions of the flow path switching sleeve (200) include a first switching position (201), a second switching position (202), and a third switching position (203). The homogenization stirring includes axial lifting, radial reflux, near-wall scraping, and reflow lifting of the crystal slurry in sequence during the crystallization process.

2. The method for homogenizing and stirring potassium nitrate crystals as described in claim 1, characterized in that: The first switching position (201) includes the following: in the first switching position (201), the inner circulation lifting zone (101) and the outer circulation reflux zone (102) are connected through the first window group, and the crystal slurry at the bottom of the crystallization container (100) is sent into the inner circulation lifting zone (101) through the lower lifting stirring member (300). The second switching position (202) includes that, in the second switching position (202), the external circulation reflux zone (102) and the near-wall reflux zone (103) are connected through the second window group, and the rich crystal slurry on the inner wall side of the crystallization container (100) is sent into the external circulation reflux zone (102) by the scraping reflux member (400). The third switching position (203) includes the following: in the third switching position (203), the near-wall reflux zone (103) and the internal circulation lifting zone (101) are connected through the third window group, and the rich crystal slurry from the near-wall reflux zone (103) and the crystal slurry from the bottom of the crystallization container (100) are combined in the suction area (301) of the lower lifting stirring member (300).

3. The method for homogenizing potassium nitrate crystals by stirring as described in claim 1 or 2, characterized in that: Before or during the adjustment of the switching position of the flow path switching sleeve (200), collect crystal slurry status data and execution status data; The crystal slurry state data includes at least two of the following: temperature, density, turbidity, and particle size characterization values ​​within the crystallization container (100); The execution status data includes at least two of the following: the driving current of the lower lifting stirring component (300), the stirring torque, the load value of the scraping return component (400), and the position feedback value of the flow path switching sleeve (200); A crystallization homogenization state characterization quantity is generated based on the slurry state data and the execution state data.

4. The method for homogenizing potassium nitrate crystals by stirring as described in claim 3, characterized in that: Based on the crystallization homogenization state characterization values, bottom rich crystal characterization values, near-wall rich crystal characterization values, and cyclic short-circuit characterization values ​​are generated respectively. The bottom rich crystal characterization, near-wall rich crystal characterization, and cycle short-circuit characterization are matched with the preset switching threshold to generate the flow path switching state. The flow path switching states include a lifting and recirculation state corresponding to the first switching position (201), a near-wall scraping state corresponding to the second switching position (202), a recirculation and lifting state corresponding to the third switching position (203), and an intermediate closed state located between adjacent switching positions.

5. The method for homogenizing potassium nitrate crystals by stirring as described in claim 1, 2, or 4, characterized in that: The flow path switching state includes generating a target switching position for the flow path switching sleeve (200) based on the flow path switching state; When the flow path switching sleeve (200) moves from the current switching position to the target switching position, the flow path switching sleeve (200) first enters the intermediate closed state and then enters the target switching position; When the position feedback value of the flow path switching sleeve (200) matches the alignment condition of the window group corresponding to the target switching position, a stirring execution command corresponding to the target switching position is generated.

6. The method for homogenizing potassium nitrate crystals by stirring as described in claim 5, characterized in that: The stirring execution command includes, The residence time of the flow path switching sleeve (200), the rotation speed of the lower lifting stirring component (300), the scraping speed of the scraping return component (400), and the switching waiting time; The stirring execution command at the first switching position (201) includes the lifting speed of the lower lifting stirring component (300); The stirring execution command at the second switching position (202) includes the scraping speed of the scraping return member (400); The stirring execution command at the third switching position (203) includes the synchronous execution time of the lower lifting stirring component (300) and the scraping return component (400).

7. The method for homogenizing potassium nitrate crystals by stirring as described in claim 1, 2, 4 or 6, characterized in that: After completing a switching cycle consisting of the first switching position (201), the second switching position (202), and the third switching position (203), crystal slurry state data and execution state data are collected, and the crystal homogenization state characterization quantity is updated based on the collected data; When the difference between the updated crystallization homogenization state characterization value and the crystallization homogenization state characterization value corresponding to the previous switching cycle falls into the preset correction range, the residence time of at least one switching position or at least one stirring execution command in the next switching cycle is adjusted.

8. The method for homogenizing potassium nitrate crystals by stirring as described in claim 7, characterized in that: When the position feedback value of the flow path switching sleeve (200) does not meet the window group alignment condition, the correspondence between the driving current and stirring torque of the lower lifting stirring component (300) falls into the preset clamping judgment range, keeping the flow path switching sleeve (200) in the middle closed state and generating a reset switching command; The reset switching command includes the reverse micro-motion angle of the flow path switching sleeve (200), the reset waiting time, and the target switching position after reset.

9. A potassium nitrate crystallization homogenization stirring apparatus, employing the potassium nitrate crystallization homogenization stirring method as described in any one of claims 1 to 8, characterized in that: It includes a crystallization container (100), a flow path switching sleeve (200), a lower lifting and stirring component (300), a scraping and reflux component (400), a fixed flow guiding component (500), a switching drive component (600), a crystallization state acquisition unit (700), and a control unit (800). The fixed flow guiding component (500) is disposed inside the crystallization container (100) and cooperates with the crystallization container (100) to form an inner circulation lifting zone (101), an outer circulation reflux zone (102) and a near-wall reflux zone (103). The flow path switching sleeve (200) is connected to the switching drive component (600) and is provided with a first window group, a second window group and a third window group; The crystallization state acquisition unit (700) is respectively disposed in at least two of the crystallization container (100), the lower lifting and stirring component (300), the scraping and reflux component (400), and the flow path switching sleeve (200); The control unit (800) is connected to the crystallization state acquisition unit (700), the switching drive component (600), the lower lifting and stirring component (300), and the scraping and reflux component (400), respectively.

10. A potassium nitrate crystallization homogenization stirring apparatus, employing the potassium nitrate crystallization homogenization stirring method as described in any one of claims 1 to 8, characterized in that: The control unit (800) includes a state characterization module (801), a switching state generation module (802), an execution instruction generation module (803), and a feedback correction module (804). The state characterization module (801) is used to generate a crystallization homogenization state characterization quantity based on the data collected by the crystallization state acquisition unit (700); The switching state generation module (802) is used to generate the flow path switching state based on the crystallization homogenization state characterization quantity; The execution instruction generation module (803) is used to generate execution instructions for the flow path switching sleeve (200), the lower lifting stirring component (300), and the scraping return component (400) according to the flow path switching status; The feedback correction module (804) is used to correct the execution command of the next switching cycle based on the position feedback value of the flow path switching sleeve (200) and the execution status data.

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