A method for preparing granular cellulose acetate based on two-stage pulverization by sedimentation

Abstract

The present application relates to chemical preparation technical field, propose a kind of granular cellulose acetate preparation method based on two-stage crushing of sedimentation, the method includes: into the container of being equipped with sedimentation medium injects the solution to be handled, simultaneously collects the real-time viscosity of mixed system, according to the viscosity data control two kinds of material flow, prepare initial sedimentation particle suspension;Monitoring the cumulative particle size distribution of suspension particles, combined with preset size threshold adjusts primary crushing intensity, obtains coarse crushing material;Subsequently, the solid phase of material is carried out displacement washing, obtain wet particles;Wet particles are sent into two-stage crushing area, inlet gas and monitor outlet material instantaneous particle size, compare target particle size range deviation, to adjust carrier gas flow rate and proportion, complete fine crushing and obtain powder;Finally, fine crushing powder is sequentially dried, classified and processed, and finally prepared into finished granular material;The present application can improve the efficiency of granular cellulose acetate preparation.

Description

Technical Field

[0001] This invention relates to the field of chemical preparation technology, and in particular to a method for preparing granular cellulose acetate based on two-stage precipitation and pulverization. Background Technology

[0002] The existing cellulose acetate particle preparation process lacks a real-time viscosity monitoring and flow dynamic control mechanism during the precipitation stage. The operating state of the precipitation system is difficult to maintain stability, which can easily lead to unstable initial particle formation quality, poor particle uniformity, and affect the continuity of the entire preparation process.

[0003] Traditional processing methods mostly employ a single crushing process, which cannot adjust operating parameters in a timely manner based on changes in particle size. Furthermore, they lack full-process online monitoring and closed-loop control of washing effects, material moisture content, and finished product particle size. This results in a dispersed particle size distribution in the finished product, making it difficult to accurately control material cleanliness and moisture content. Consequently, there are significant shortcomings in overall production quality and processing efficiency. Therefore, improving the preparation efficiency of granular cellulose acetate has become an urgent problem to be solved. Summary of the Invention

[0004] This invention provides a method for preparing granular cellulose acetate based on two-stage precipitation and pulverization, in order to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides a method for preparing granular cellulose acetate based on two-stage precipitation and pulverization, comprising:

[0006] A. Inject the cellulose acetate solution to be treated into a precipitation container containing a precipitation medium, and simultaneously collect real-time viscosity data of the mixture in the precipitation container;

[0007] B. Based on the real-time viscosity data, adjust the replenishment flow rate of the precipitation medium and the injection flow rate of the solution to be treated to obtain the initial precipitated cellulose acetate particle suspension;

[0008] C. Monitor the cumulative particle size distribution data of the particles in the initial sedimentation particle suspension, and control the processing intensity of the first-stage crushing zone based on the comparison result between the cumulative particle size distribution data and the preset first size threshold to obtain the coarsely crushed cellulose acetate material.

[0009] D. The solid phase in the coarsely pulverized material is subjected to displacement washing to obtain the washed wet granules of cellulose acetate;

[0010] E. The washed wet particles are conveyed to the second-stage crushing treatment zone, where auxiliary medium carrier gas is introduced and the instantaneous particle size data of the material at the outlet of the second-stage crushing treatment zone is monitored in real time.

[0011] F. Perform a difference analysis between the instantaneous particle size data and the target particle size range of cellulose acetate to obtain the particle size deviation value of cellulose acetate, and adjust the flow rate and ratio of the auxiliary medium carrier gas according to the particle size deviation value to obtain finely pulverized cellulose acetate powder.

[0012] G. The finely pulverized powder is dried, and the dried powder is graded to obtain the final granular material of cellulose acetate.

[0013] In a preferred embodiment, the step of injecting the cellulose acetate solution to be treated into a precipitation container containing a precipitation medium, while simultaneously collecting real-time viscosity data of the mixture within the precipitation container, includes:

[0014] According to the preset injection flow rate, the cellulose acetate solution to be treated is injected at a uniform rate into the precipitation container containing the precipitation medium.

[0015] During the uniform injection process, the instantaneous viscosity values ​​of the mixture in the precipitation vessel are continuously recorded to obtain the original viscosity sequence of the mixture.

[0016] Linear interpolation is performed on the outliers in the original viscosity sequence to obtain the intermediate viscosity sequence of the mixture;

[0017] The intermediate viscosity sequence is numerically smoothed to obtain the real-time viscosity data of the mixture.

[0018] In a preferred embodiment, adjusting the replenishment flow rate of the precipitation medium and the injection flow rate of the solution to be treated based on the real-time viscosity data to obtain the initial precipitated cellulose acetate particle suspension includes:

[0019] The real-time viscosity data is compared with the preset target viscosity range to obtain the precipitation control scheme of cellulose acetate.

[0020] When the real-time viscosity data is higher than the upper limit of the target viscosity range, increase the replenishment flow rate of the precipitation medium and simultaneously decrease the injection flow rate of the solution to be treated.

[0021] When the real-time viscosity data is lower than the lower limit of the target viscosity range, the replenishment flow rate of the precipitation medium is reduced while the injection flow rate of the solution to be treated is increased.

[0022] When the real-time viscosity data is within the target viscosity range, the replenishment flow rate of the precipitation medium and the injection flow rate of the solution to be treated are kept constant.

[0023] According to the precipitation control scheme, the solution to be treated is continuously injected to obtain the initial precipitated cellulose acetate particle suspension.

[0024] In a preferred embodiment, the monitoring of the cumulative particle size distribution data of the particles in the initial sedimentation particle suspension, and the control of the processing intensity of the first-stage grinding zone based on the comparison result between the cumulative particle size distribution data and a preset first size threshold, to obtain the coarsely ground cellulose acetate material, comprising:

[0025] Obtain a particle size test sample of the initial sedimentation particle suspension to obtain particle size data of the particle size test sample;

[0026] The cumulative integral transform of the particle size data is performed to obtain the cumulative particle size distribution data of the particle size detection sample;

[0027] The cumulative particle size distribution data is parameterized and mapped to a preset first size threshold to obtain representative particle size data of the particle size detection sample;

[0028] Based on the representative particle size data and the first size threshold, a first-stage pulverization treatment zone control command for the cellulose acetate is generated, and the first-stage pulverization treatment zone control command is responded to to obtain coarsely pulverized cellulose acetate material.

[0029] In a preferred embodiment, the step of generating a first-stage pulverization zone control command for the cellulose acetate based on the representative particle size data and the first size threshold, and responding to the first-stage pulverization zone control command to obtain coarsely pulverized cellulose acetate material, includes:

[0030] When the representative particle size data is greater than the first size threshold, the processing intensity of the first-stage crushing zone is increased to obtain an enhanced control command for the first-stage crushing zone.

[0031] When the representative particle size data is smaller than the first size threshold, the processing intensity of the first-stage crushing processing zone is reduced, and a reduction control command for the first-stage crushing processing zone is obtained.

[0032] When the representative particle size data is equal to the first size threshold, the processing intensity of the first-stage crushing processing zone is kept constant, and a stable control command for the first-stage crushing processing zone is obtained.

[0033] Based on the enhanced control command, the reduced control command, and the stable control command, the particles in the initial sedimentation particle suspension are subjected to a first-stage crushing process to obtain the coarsely crushed cellulose acetate material.

[0034] In a preferred embodiment, the step of displacement washing of the solid phase in the coarsely pulverized material to obtain the washed wet granules of cellulose acetate includes:

[0035] The coarsely pulverized material is subjected to solid-liquid separation to obtain the solid phase of the coarsely pulverized material;

[0036] The solid phase is subjected to displacement washing using a washing medium, and real-time index data of the washing waste liquid is continuously collected during the displacement washing process to obtain the waste liquid monitoring sequence of the solid phase.

[0037] The index values ​​in the waste liquid monitoring sequence are compared one by one with the preset washing endpoint threshold to obtain the washed wet granules of cellulose acetate.

[0038] In a preferred embodiment, the step of performing a difference analysis between the instantaneous particle size data and the target particle size range of cellulose acetate to obtain a particle size deviation value of the cellulose acetate, and adjusting the flow rate and ratio of the auxiliary medium carrier gas according to the particle size deviation value to obtain finely pulverized cellulose acetate powder, includes:

[0039] The instantaneous particle size data is weighted and averaged to obtain the weighted representative particle size value of the material.

[0040] Obtain the geometric center value of the target particle size range in the cellulose acetate, and perform normalized difference between the weighted representative particle size value and the geometric center value to obtain the relative deviation rate of the cellulose acetate.

[0041] The adjustment coefficient of the auxiliary medium carrier gas is calculated based on the relative deviation rate.

[0042] Multiply the adjustment coefficient by the current flow rate of the auxiliary medium carrier gas to obtain the target flow rate of the auxiliary medium carrier gas;

[0043] The target ratio of the auxiliary medium carrier gas is obtained by performing a scalar multiplication transformation on the adjustment coefficient and the current ratio of the auxiliary medium carrier gas.

[0044] Based on the target flow rate and the target ratio, the washed wet particles are subjected to a second-stage pulverization process to obtain finely pulverized cellulose acetate powder.

[0045] In a preferred embodiment, the formula for calculating the adjustment coefficient is:

[0046] ;

[0047] in, This represents the adjustment coefficient. This represents the preset single adjustment coefficient. This represents the relative deviation rate. Represents the natural constant.

[0048] In a preferred embodiment, the drying process of the finely pulverized powder and the grading process of the dried powder to obtain the final granular material of cellulose acetate include:

[0049] Based on the target moisture threshold of cellulose acetate, the finely pulverized powder is dried, and real-time moisture content data of the finely pulverized powder is continuously collected during the drying process to obtain the moisture content sequence of the finely pulverized powder.

[0050] The values ​​in the moisture content sequence are compared with the target moisture threshold one by one to obtain the dried cellulose acetate powder.

[0051] Obtain the overall particle size distribution data of the dried powder, and determine the classification of the overall particle size distribution data with the target particle size range to obtain the final granular material of cellulose acetate.

[0052] In a preferred embodiment, the step of determining the attribution of the overall particle size distribution data to the target particle size range to obtain the final granular material of cellulose acetate includes:

[0053] If the overall particle size distribution data is higher than the upper limit of the target particle size range, the dried powder is marked as coarse powder to be returned and the dried powder is returned to the first-stage crushing processing area.

[0054] If the overall particle size distribution data is lower than the lower limit of the target particle size range, the dried powder is marked as fine powder to be returned and the dried powder is returned to the second-stage crushing processing area.

[0055] If the overall particle size distribution data is within the target particle size range, the dried powder is marked as qualified powder, and the final granular material of cellulose acetate is obtained.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] 1. This invention collects viscosity data of the mixture in real time during the precipitation process and dynamically adjusts the flow rate of the solution to be treated and the precipitation medium based on the data, so that the precipitation process remains stable. This not only ensures the formation effect of the initial precipitated particles, but also allows the entire preparation process to be carried out continuously and smoothly, effectively improving the overall preparation efficiency of granular cellulose acetate.

[0058] 2. This invention employs a two-stage pulverization mode, which monitors particle size in real time throughout the process. It adaptively adjusts the pulverization intensity and the flow rate and ratio of the auxiliary carrier gas based on particle size deviation. Combined with online washing monitoring, moisture control, and finished product grading, sorting, and return processing, it can precisely control the particle size, cleanliness, and moisture content of the finished product particles, resulting in more uniform indicators of the produced granular cellulose acetate and comprehensive optimization of the overall product quality. Attached Figure Description

[0059] Figure 1 This is a schematic flowchart of a method for preparing granular cellulose acetate based on two-stage precipitation and pulverization according to an embodiment of the present invention.

[0060] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0061] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0062] This application provides a method for preparing granular cellulose acetate based on two-stage precipitation and pulverization. The execution entity of this method includes, but is not limited to, at least one of the following electronic devices that can be configured to execute the method provided in this application: a server, a terminal, etc. In other words, the method for preparing granular cellulose acetate based on two-stage precipitation and pulverization can be executed by software or hardware installed on a terminal device or a server device. The server includes, but is not limited to, a single server, a server cluster, a cloud server, or a cloud server cluster. The server can be an independent server or a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communication, middleware services, domain name services, security services, content delivery networks (CDNs), and big data and artificial intelligence platforms.

[0063] Reference Figure 1 The diagram shown is a schematic flow chart of a method for preparing granular cellulose acetate based on two-stage precipitation and pulverization according to an embodiment of the present invention. In this embodiment, the method for preparing granular cellulose acetate based on two-stage precipitation and pulverization includes:

[0064] A. Inject the cellulose acetate solution to be treated into a precipitation container containing a precipitation medium, and simultaneously collect real-time viscosity data of the mixture in the precipitation container;

[0065] In this embodiment of the invention, the step of injecting the cellulose acetate solution to be treated into a precipitation container containing a precipitation medium, and simultaneously collecting real-time viscosity data of the mixture within the precipitation container, includes:

[0066] According to the preset injection flow rate, the cellulose acetate solution to be treated is injected at a uniform rate into the precipitation container containing the precipitation medium.

[0067] During the uniform injection process, the instantaneous viscosity values ​​of the mixture in the precipitation vessel are continuously recorded to obtain the original viscosity sequence of the mixture.

[0068] Linear interpolation is performed on the outliers in the original viscosity sequence to obtain the intermediate viscosity sequence of the mixture;

[0069] The intermediate viscosity sequence is numerically smoothed to obtain the real-time viscosity data of the mixture.

[0070] The precipitation container is pre-filled with sufficient precipitation medium. The delivery pipeline operates continuously at a pre-set, calibrated constant flow rate. The cellulose acetate solution to be treated flows smoothly into the precipitation container through the delivery pipeline. The flow rate remains constant throughout the injection process, allowing the solution to be treated to gradually come into full contact with and mix with the precipitation medium in the container. The preparation method of the cellulose acetate solution to be treated is as follows: cellulose acetate powder with a degree of polymerization of 150-300 and an acetyl content of 54%-56% is added to a mixed solvent of acetone and ethyl acetate in a volume ratio of 7:3. The mixture is stirred at 30-40℃ for 2-4 hours until completely dissolved, yielding a cellulose acetate solution with a mass concentration of 8%-12%. The precipitation medium is a mixed solution of deionized water and acetone in a volume ratio of 9:1. The initial volume of the precipitation medium in the precipitation container is 3-5 times the total volume of the solution to be treated.

[0071] Throughout the process of the solution to be treated being continuously and uniformly injected into the precipitation container and the materials being continuously mixed, a dedicated viscosity detection device continuously collects data, sequentially capturing the viscosity value of the mixture at each moment in the container. All the instantaneous viscosity values ​​collected are arranged and stored in the order of collection, and the complete set of values ​​formed after arrangement and integration is the original viscosity sequence of the mixture.

[0072] Each value in the original viscosity sequence is checked one by one to accurately locate abnormal values ​​that do not conform to the normal variation pattern. The location of each abnormal value is determined, and the two sets of normal viscosity values ​​immediately before and after the location are extracted as reference standards. According to the law of continuous linear change, the reasonable value corresponding to the abnormal position is calculated. The calculated reasonable value is used to replace the original abnormal value. After the replacement of all abnormal values ​​in the sequence is completed, the entire set of values ​​is reorganized. The new set of values ​​obtained after reorganization is the intermediate viscosity sequence of the mixture.

[0073] Each value in the intermediate viscosity sequence and its surrounding multiple effective values ​​are selected for comprehensive calculation. The corresponding correction value is obtained based on the calculation result. The original value with abrupt fluctuations in the sequence is replaced with the correction value. The correction operation of all values ​​in the intermediate viscosity sequence is completed in the same way to eliminate abrupt fluctuations between values. The final set of values ​​obtained after completing the entire correction process is the real-time viscosity data of the mixture in the precipitation vessel.

[0074] The beneficial effects include: uniform material injection ensures a stable mixing rhythm between the solution to be treated and the precipitation medium; continuous acquisition of instantaneous viscosity values ​​can completely record the entire viscosity change of the mixture; linear interpolation can completely eliminate abnormal values ​​generated during data acquisition, avoiding abnormal data from affecting subsequent control judgments; numerical smoothing further optimizes the continuity and stability of the data; the entire data processing process can ensure that the final real-time viscosity data is accurate and reliable, providing solid data support for subsequent precise adjustment of the precipitation medium replenishment flow rate and the solution to be treated injection flow rate, ensuring stable operating conditions in the precipitation process, and improving the forming quality and uniformity of the primary cellulose acetate precipitate particles.

[0075] B. Based on the real-time viscosity data, adjust the replenishment flow rate of the precipitation medium and the injection flow rate of the solution to be treated to obtain the initial precipitated cellulose acetate particle suspension;

[0076] In this embodiment of the invention, adjusting the replenishment flow rate of the precipitation medium and the injection flow rate of the solution to be treated based on the real-time viscosity data to obtain the initial precipitated cellulose acetate particle suspension includes:

[0077] The real-time viscosity data is compared with the preset target viscosity range to obtain the precipitation control scheme of cellulose acetate.

[0078] When the real-time viscosity data is higher than the upper limit of the target viscosity range, increase the replenishment flow rate of the precipitation medium and simultaneously decrease the injection flow rate of the solution to be treated.

[0079] When the real-time viscosity data is lower than the lower limit of the target viscosity range, the replenishment flow rate of the precipitation medium is reduced while the injection flow rate of the solution to be treated is increased.

[0080] When the real-time viscosity data is within the target viscosity range, the replenishment flow rate of the precipitation medium and the injection flow rate of the solution to be treated are kept constant.

[0081] According to the precipitation control scheme, the solution to be treated is continuously injected to obtain the initial precipitated cellulose acetate particle suspension.

[0082] The complete numerical range corresponding to the target viscosity range set in advance in the system is 15-25 mPa·s (measured at 25℃). The real-time viscosity data collected is compared with this numerical range item by item. Based on the different results of the comparison, the corresponding on-site operation method is matched. The comparison conclusion and the matching operation method are integrated to form a complete cellulose acetate precipitation control scheme.

[0083] Once the real-time viscosity data exceeds the upper limit of the target viscosity range, the conveying equipment for the precipitation medium is adjusted to increase the flow rate of the replenished medium, while the conveying equipment for the solution to be treated is adjusted to decrease the flow rate of the injected solution. The adjustment actions of the two devices are completed synchronously and operate stably.

[0084] After determining that the real-time viscosity data value has not reached the lower limit value corresponding to the target viscosity range, the conveying equipment corresponding to the precipitation medium is adjusted to reduce the flow rate of medium replenishment, and the conveying equipment corresponding to the solution to be treated is adjusted simultaneously to increase the flow rate of solution injection. The adjustment actions of the two devices are completed synchronously and operate stably.

[0085] Once the real-time viscosity data is determined to be within the range corresponding to the target viscosity range, no adjustments are made to the conveying equipment corresponding to the replenishment flow rate of the precipitation medium and the injection flow rate of the solution to be treated, so that the conveying rate of the two types of materials remains unchanged in the current operating state.

[0086] Throughout the process, the pre-established precipitation control scheme is followed to execute various flow control actions, ensuring that the cellulose acetate solution to be treated is continuously fed into the precipitation container. The solution and precipitation medium are continuously mixed and the precipitation process is completed. Gradually, a mixed material system with dispersed particles is formed in the container, and finally, a primary precipitated cellulose acetate particle suspension is obtained.

[0087] The beneficial effects are that a customized precipitation control scheme is formulated based on the comparison results of real-time viscosity data and preset ranges. Corresponding flow adjustment actions are performed for different viscosity ranges, which can keep the viscosity of the mixture in the precipitation container stable within the standard working range, ensure constant environmental conditions for the cellulose acetate precipitation reaction, promote uniform particle morphology and good dispersion, and obtain a stable initial precipitated particle suspension. At the same time, the entire control method can realize continuous automated operation of the process, reduce manual intervention, and improve the overall operational stability and production efficiency of the cellulose acetate preparation process.

[0088] C. Monitor the cumulative particle size distribution data of the particles in the initial sedimentation particle suspension, and control the processing intensity of the first-stage crushing zone based on the comparison result between the cumulative particle size distribution data and the preset first size threshold to obtain the coarsely crushed cellulose acetate material.

[0089] In this embodiment of the invention, the monitoring of the cumulative particle size distribution data of the particles in the initial sedimentation particle suspension, and the control of the processing intensity of the first-stage pulverization zone based on the comparison result between the cumulative particle size distribution data and a preset first size threshold, to obtain the coarsely pulverized cellulose acetate material, includes:

[0090] Obtain a particle size test sample of the initial sedimentation particle suspension to obtain particle size data of the particle size test sample;

[0091] The cumulative integral transform of the particle size data is performed to obtain the cumulative particle size distribution data of the particle size detection sample;

[0092] The cumulative particle size distribution data is parameterized and mapped to a preset first size threshold to obtain representative particle size data of the particle size detection sample;

[0093] Based on the representative particle size data and the first size threshold, a first-stage pulverization treatment zone control command for the cellulose acetate is generated, and the first-stage pulverization treatment zone control command is responded to to obtain coarsely pulverized cellulose acetate material.

[0094] The step of generating a first-stage pulverization zone control command for the cellulose acetate based on the representative particle size data and the first size threshold, and responding to the first-stage pulverization zone control command to obtain coarsely pulverized cellulose acetate material, includes:

[0095] When the representative particle size data is greater than the first size threshold, the processing intensity of the first-stage crushing zone is increased to obtain an enhanced control command for the first-stage crushing zone.

[0096] When the representative particle size data is smaller than the first size threshold, the processing intensity of the first-stage crushing processing zone is reduced, and a reduction control command for the first-stage crushing processing zone is obtained.

[0097] When the representative particle size data is equal to the first size threshold, the processing intensity of the first-stage crushing processing zone is kept constant, and a stable control command for the first-stage crushing processing zone is obtained.

[0098] Based on the enhanced control command, the reduced control command, and the stable control command, the particles in the initial sedimentation particle suspension are subjected to a first-stage crushing process to obtain the coarsely crushed cellulose acetate material.

[0099] An appropriate amount of initial sedimentation particle suspension is extracted from the normal transport process as a test sample. The actual size information of all particles in the sample is detected one by one using a dedicated particle size detection device. All test results are collected and summarized to obtain the particle size data of the particle size test sample.

[0100] According to the sorting rule of particle size from smallest to largest, the proportion of particles in each size range is counted in turn. The statistical results of different size ranges are continuously superimposed to complete the data accumulation and integration of the entire size range. After complete data superposition processing, the cumulative particle size distribution data of the particle size detection sample is obtained.

[0101] The accumulated particle size distribution data is compared with the pre-set first size threshold item by item. Based on the correspondence between the two, the data matching and conversion is completed. Values ​​that can reflect the comprehensive size characteristics of the whole batch of particles are selected from the overall distribution data. After the data matching and conversion operation is completed, the representative particle size data of the particle size test sample is obtained. The first size threshold is 150μm (that is, the representative particle size of the coarsely crushed material after primary crushing should be controlled within the range of 150μm±20μm).

[0102] The obtained representative particle size data is compared with the preset first size threshold. Based on the comparison results, the operating requirements of the first-stage crushing treatment zone are determined, and control instructions for the first-stage crushing treatment zone of cellulose acetate are compiled. The equipment in the crushing zone receives the instructions and prepares for operation according to the instructions.

[0103] After comparing the two sets of values ​​and confirming that the value of the representative particle size data is higher than the first size threshold, the operating conditions of the operating components in the first-stage crushing treatment zone are adjusted to enhance the crushing force of the equipment on the particles, thereby generating enhanced control commands for the first-stage crushing treatment zone.

[0104] After comparing the two sets of values ​​and confirming that the value of the representative particle size data is lower than the first size threshold, the operating conditions of the operating components in the first-stage crushing treatment zone are adjusted to reduce the crushing force of the equipment on the particles, thereby generating a reduction control command for the first-stage crushing treatment zone.

[0105] After comparing the two sets of values, it is confirmed that the value of the representative particle size data is exactly the same as the first size threshold. No changes are made to the operating conditions of the operating components in the first-stage crushing and processing zone, and the current crushing force is kept unchanged, thereby generating a stable control command for the first-stage crushing and processing zone.

[0106] The equipment in the first-stage crushing zone recognizes the currently effective control commands and operates strictly according to the processing intensity set by the commands. The initial sedimentation particle suspension is continuously transported to the crushing area, where the equipment performs mechanical crushing operations on the particles inside the suspension. After all particles complete the first-stage crushing process, coarsely crushed cellulose acetate material is obtained.

[0107] The beneficial effects are that by obtaining real particle size data through sampling and testing, and then obtaining representative data that reflects the overall particle size through data transformation and parameter mapping, combined with the dynamic switching of the crushing intensity based on preset thresholds, the first-stage crushing operation can always match the actual size state of the initially settled particles, effectively ensuring the uniformity of particle size of the coarsely crushed material. At the same time, the entire data monitoring and command control process can realize the automated connection of processes, reduce errors caused by human operation, improve the operational stability of the crushing process and the quality of material processing, and also lay a good foundation for subsequent washing, secondary crushing and other processes.

[0108] D. The solid phase in the coarsely pulverized material is subjected to displacement washing to obtain the washed wet granules of cellulose acetate;

[0109] In this embodiment of the invention, the step of displacement washing of the solid phase in the coarsely pulverized material to obtain the washed wet granules of cellulose acetate includes:

[0110] The coarsely pulverized material is subjected to solid-liquid separation to obtain the solid phase of the coarsely pulverized material;

[0111] The solid phase is subjected to displacement washing using a washing medium, and real-time index data of the washing waste liquid is continuously collected during the displacement washing process to obtain the waste liquid monitoring sequence of the solid phase.

[0112] The index values ​​in the waste liquid monitoring sequence are compared one by one with the preset washing endpoint threshold to obtain the washed wet granules of cellulose acetate.

[0113] The coarsely crushed material is transported into the solid-liquid separation equipment, where the liquid and solid components in the material are separated by physical separation. The solid material collected after the component separation is completed is the solid phase of the coarsely crushed material.

[0114] The prepared washing medium, i.e., deionized water, is continuously passed into the washing device containing the solid phase, allowing the washing medium to continuously penetrate the surface and internal pores of the solid phase, gradually displacing the residual substances attached to the solid phase. During the entire replacement washing process, the washing temperature should be controlled at 20-30℃, and the mass ratio of washing medium to solid phase should be 5-8:1. The monitoring equipment continuously collects various indicator information corresponding to the washing waste liquid discharged at each time period. All waste liquid indicator information collected in chronological order is arranged and summarized in sequence, and the final complete data set is the solid phase waste liquid monitoring sequence.

[0115] The values ​​of each indicator in the waste liquid monitoring sequence are extracted sequentially, and each indicator value is compared and verified with the pre-set washing endpoint threshold. When the monitored indicator value stably reaches the judgment standard corresponding to the washing endpoint threshold, the real-time indicator data of the washing waste liquid is conductivity. The preset washing endpoint threshold is ≤10μS / cm (measured at 25℃). When the conductivity of the washing waste liquid is ≤10μS / cm for 3 consecutive tests, the washing is judged to be completed, the delivery of washing medium into the washing device is stopped, and the replacement washing process is ended. The processed solid material is taken out from the washing device. This part of the material is the washed wet granules of cellulose acetate.

[0116] The benefits include the ability to precisely separate liquid components from coarsely ground materials through solid-liquid separation, allowing the washing process to target only the effective solid materials, thus improving the targeting of the washing operation. The displacement washing method can thoroughly remove residual impurities attached to the surface and interior of the solid phase. Continuous collection of waste liquid indicators and comparison with the washing endpoint threshold one by one can accurately control the timing of washing termination, ensuring that the cleanliness of cellulose acetate particles meets production requirements while avoiding unnecessary consumption of washing media and changes in material properties due to excessive washing time. This effectively improves the operational quality and efficiency of the washing process, providing stable raw materials for the subsequent second-stage crushing process.

[0117] E. The washed wet particles are conveyed to the second-stage crushing treatment zone, where auxiliary medium carrier gas is introduced and the instantaneous particle size data of the material at the outlet of the second-stage crushing treatment zone is monitored in real time.

[0118] In this embodiment of the invention, the washed wet particles are smoothly conveyed to the working space of the second-stage crushing and processing zone via a dedicated conveying device. The material continuously enters the working area at a predetermined rate, ensuring that the material feeding state is continuous and evenly distributed.

[0119] Open the auxiliary medium carrier gas delivery pipeline to allow the auxiliary medium carrier gas to continuously flow into the second-stage crushing and processing zone. The carrier gas forms a stable airflow environment in the working space and accompanies the crushing process of the material throughout. The auxiliary medium carrier gas is a mixture of nitrogen and compressed air in a volume ratio of 1:1, with an initial flow velocity of 15-25 m / s and an initial pressure of 0.3-0.5 MPa.

[0120] When the second-stage crushing and processing zone is in normal operation, the particle size detection device is always aligned with the material outlet position of the zone to carry out uninterrupted data collection. It captures the particle size information of the material discharged from the outlet at every moment in real time. After collecting all the collected size information, it forms the instantaneous particle size data of the material at the outlet of the second-stage crushing and processing zone.

[0121] The beneficial effects include stable conveying of washed wet particles, allowing the second-stage crushing process to maintain continuous feeding; the introduction of auxiliary medium carrier gas can improve the flow pattern of materials in the crushing area, preventing wet particles from agglomerating; and real-time acquisition of instantaneous particle size data of the outlet material can accurately grasp the actual effect of the current crushing operation, providing intuitive and reliable data support for subsequent adjustment of the flow rate and ratio of the auxiliary medium carrier gas, ensuring that the second-stage crushing operation is always under control, and effectively improving the uniformity and overall quality of powder processing.

[0122] F. Perform a difference analysis between the instantaneous particle size data and the target particle size range of cellulose acetate to obtain the particle size deviation value of cellulose acetate, and adjust the flow rate and ratio of the auxiliary medium carrier gas according to the particle size deviation value to obtain finely pulverized cellulose acetate powder.

[0123] In this embodiment of the invention, the step of performing a difference analysis between the instantaneous particle size data and the target particle size range of cellulose acetate to obtain the particle size deviation value of the cellulose acetate, and adjusting the flow rate and ratio of the auxiliary medium carrier gas according to the particle size deviation value to obtain finely pulverized cellulose acetate powder, includes:

[0124] The instantaneous particle size data is weighted and averaged to obtain the weighted representative particle size value of the material.

[0125] Obtain the geometric center value of the target particle size range in the cellulose acetate, and perform normalized difference between the weighted representative particle size value and the geometric center value to obtain the relative deviation rate of the cellulose acetate.

[0126] The adjustment coefficient of the auxiliary medium carrier gas is calculated based on the relative deviation rate.

[0127] Multiply the adjustment coefficient by the current flow rate of the auxiliary medium carrier gas to obtain the target flow rate of the auxiliary medium carrier gas;

[0128] The target ratio of the auxiliary medium carrier gas is obtained by performing a scalar multiplication transformation on the adjustment coefficient and the current ratio of the auxiliary medium carrier gas.

[0129] Based on the target flow rate and the target ratio, the washed wet particles are subjected to a second-stage pulverization process to obtain finely pulverized cellulose acetate powder.

[0130] The formula for calculating the adjustment coefficient is as follows:

[0131] ;

[0132] in, This represents the adjustment coefficient. This represents the preset single adjustment coefficient. This represents the relative deviation rate. Represents the natural constant.

[0133] Collect all instantaneous particle size data of the material at the outlet of the second-stage crushing and processing zone. Assign corresponding weight values ​​according to the particle distribution ratio of different particle size data. Combine each set of particle size data with the matched weight in sequence to carry out calculation. After summarizing all calculation results, complete the overall mean calculation. After the calculation is completed, the weighted representative particle size value of the material is obtained.

[0134] The target particle size range of cellulose acetate in the extraction system is 20-50 μm. Based on two sets of boundary values, the geometric center value corresponding to this particle size range is calculated to be 31.6 μm. The weighted representative particle size value and the geometric center value are then calculated by difference. A unified standardized conversion method is used to process the difference to eliminate the interference caused by the magnitude of the numerical values. After processing, the relative deviation rate of cellulose acetate is obtained.

[0135] Referring to the particle size deviation reflected by the obtained relative deviation rate, the calculation work is carried out step by step according to the established calculation logic. The corresponding adjustment range is determined based on the actual degree of deviation. After the entire calculation process is completed, the adjustment coefficient of the auxiliary medium carrier gas is obtained.

[0136] The preset single adjustment coefficient is a fixed value set in advance based on the production standards of granular cellulose acetate and the equipment parameters of the second-stage crushing treatment zone before the equipment starts operating. The value range is 0.8-1.2, preferably 1.0. The relative deviation rate is obtained by normalized difference calculation of the weighted representative particle size value and the geometric center value of the target particle size range of cellulose acetate. The weighted representative particle size value is the result of weighted average processing of the instantaneous particle size data of the material at the outlet of the second-stage crushing treatment zone. The instantaneous particle size data is the material particle size value obtained by real-time monitoring during the second-stage crushing treatment. The geometric center value is a fixed value obtained by taking the middle position of the two ends of the predefined target particle size range of cellulose acetate. The natural constant is a fixed mathematical constant and participates in the calculation process of the adjustment coefficient throughout the process.

[0137] The entire calculation method combines a fixed mathematical constant to perform a double exponential operation on the relative deviation rate. The difference and sum of the two sets of exponential operation results are calculated separately. The two sets of calculation results are then divided to obtain the basic operation result. Subsequently, the basic operation result is added to the square of the relative deviation rate. Finally, the sum is multiplied by a preset single adjustment coefficient to obtain the adjustment coefficient used to control the auxiliary medium carrier gas. The adjustment coefficient obtained by this operation will directly affect the flow rate and ratio of the auxiliary medium carrier gas. Multiplying the calculated adjustment coefficient by the current flow rate of the auxiliary medium carrier gas will give the target flow rate of the auxiliary medium carrier gas. Multiplying the calculated adjustment coefficient by the current ratio of the auxiliary medium carrier gas will give the target ratio of the auxiliary medium carrier gas. Based on the target flow rate and target ratio, the working conditions of the second-stage crushing and processing zone are adjusted to produce finely crushed cellulose acetate powder.

[0138] As the weighted representative particle size deviates from the geometric center of the target particle size range of cellulose acetate by a continuously increasing margin, the relative deviation rate will increase accordingly. The adjustment coefficient obtained after the entire calculation will also increase, ultimately increasing the flow rate and ratio of the auxiliary medium carrier gas to improve the pulverizing effect of the second-stage pulverizing zone and reduce the gap between the material particle size and the standard range. Conversely, as the weighted representative particle size approaches the geometric center of the target particle size range of cellulose acetate, the relative deviation rate will gradually decrease, and the adjustment coefficient obtained after the entire calculation will also decrease accordingly. This will ultimately reduce the flow rate and ratio of the auxiliary medium carrier gas to weaken the pulverizing intensity of the second-stage pulverizing zone and prevent the material particle size from becoming too small. When the weighted representative particle size perfectly matches the geometric center of the target particle size range of cellulose acetate, the relative deviation rate returns to zero. The adjustment coefficient obtained after the entire calculation remains stable, and the flow rate and ratio of the auxiliary medium carrier gas no longer change. The second-stage pulverizing zone maintains its current operating conditions and stably produces finely pulverized cellulose acetate powder that meets the particle size requirements.

[0139] The current flow rate of the auxiliary medium carrier gas in the second-stage pulverizing zone is retrieved and processed with the calculated adjustment coefficient. After the calculation, the target flow rate of the auxiliary medium carrier gas is obtained.

[0140] The mixing ratio parameters of the various components of the auxiliary medium carrier gas are sorted out, and the entire set of current ratio parameters and adjustment coefficients are uniformly converted and adjusted. After the overall ratio is synchronously transformed, the target ratio of the auxiliary medium carrier gas is obtained.

[0141] The conveying conditions of the auxiliary medium carrier gas are adjusted according to the determined target flow rate and target ratio, so that the carrier gas is continuously and stably conveyed in the second-stage crushing treatment zone with new parameters. At the same time, the washed wet particles that continuously enter the working area are subjected to the second-stage crushing treatment. After the material completes the fine crushing process, finely crushed cellulose acetate powder is obtained.

[0142] The beneficial effects are as follows: By integrating multiple sets of instantaneous particle size data through weighted averaging, the comprehensive particle size of the entire batch of materials can be accurately reflected. The relative deviation rate calculated in combination with the target particle size range can accurately determine the deviation of particle size. Based on the deviation data, the adjustment coefficient, target flow rate and target ratio can be calculated layer by layer. The operating parameters of the auxiliary medium carrier gas can be dynamically adjusted according to the actual state of the material, so that the working conditions of the second-stage crushing operation are always in a reasonable state, effectively correcting the particle size deviation, ensuring the uniformity of the finely crushed powder, and the entire data processing and parameter control process is smooth and seamless, realizing automated dynamic control of the process, reducing human operation errors, and further improving the processing quality and continuous operation capability of the second-stage crushing process.

[0143] G. The finely pulverized powder is dried, and the dried powder is graded to obtain the final granular material of cellulose acetate.

[0144] In this embodiment of the invention, the drying process of the finely pulverized powder and the grading process of the dried powder to obtain the final granular material of cellulose acetate include:

[0145] Based on the target moisture threshold of cellulose acetate, the finely pulverized powder is dried, and real-time moisture content data of the finely pulverized powder is continuously collected during the drying process to obtain the moisture content sequence of the finely pulverized powder.

[0146] The values ​​in the moisture content sequence are compared with the target moisture threshold one by one to obtain the dried cellulose acetate powder.

[0147] Obtain the overall particle size distribution data of the dried powder, and determine the classification of the overall particle size distribution data with the target particle size range to obtain the final granular material of cellulose acetate.

[0148] The step of determining the attribution of the overall particle size distribution data to the target particle size range to obtain the final granular material of cellulose acetate includes:

[0149] If the overall particle size distribution data is higher than the upper limit of the target particle size range, the dried powder is marked as coarse powder to be returned and the dried powder is returned to the first-stage crushing processing area.

[0150] If the overall particle size distribution data is lower than the lower limit of the target particle size range, the dried powder is marked as fine powder to be returned and the dried powder is returned to the second-stage crushing processing area.

[0151] If the overall particle size distribution data is within the target particle size range, the dried powder is marked as qualified powder, and the final granular material of cellulose acetate is obtained.

[0152] The drying equipment is started based on the pre-set target moisture threshold of cellulose acetate. The finely pulverized powder is continuously fed into the drying equipment to carry out the drying operation. The powder moves continuously inside the equipment and completes the moisture removal. During the uninterrupted drying process, the moisture detection device continuously collects the real-time moisture content data of the finely pulverized powder at each stage according to a fixed rhythm. All the moisture content values ​​recorded in the order of collection are arranged and combined in sequence to form the moisture content sequence of the finely pulverized powder.

[0153] The moisture content value of each record in the moisture content sequence is taken out in sequence and compared with the preset target moisture threshold. When all the moisture content values ​​in the sequence meet the judgment criteria corresponding to the target moisture threshold, the operation of the drying equipment is terminated and all the material is taken out from the equipment. This part of the material is the dried powder of cellulose acetate, and the target moisture threshold is ≤0.5% (mass fraction).

[0154] A dedicated particle size detection device was used to comprehensively test the collected dried powder, and the size information of all particles inside the batch of powder was collected. After integrating and sorting all the size information, the overall particle size distribution data of the dried powder was obtained. Then, the sorted overall particle size distribution data was compared and classified with the target particle size range corresponding to cellulose acetate. Based on the comparison results, the material was classified and determined. After a complete determination process, the final granular material of cellulose acetate was obtained.

[0155] After completing the numerical comparison, it was determined that the overall particle size distribution data exceeded the upper limit of the target particle size range. The dried powder was then uniformly marked as coarse powder to be returned. At the same time, the batch of material was transported back to the first-stage crushing and processing area in the production process for reprocessing using conveying equipment.

[0156] After completing the numerical comparison, it was determined that the overall particle size distribution data did not reach the lower limit value corresponding to the target particle size range. The dried powder was uniformly marked and classified as fine powder to be returned. At the same time, the batch of material was transported back to the second-stage crushing and processing area in the production process for reprocessing using conveying equipment.

[0157] After completing the numerical comparison, it was determined that the overall particle size distribution data was within the range corresponding to the target particle size. The dried powder was then uniformly labeled and classified as qualified powder. This batch of qualified powder that meets the standard is the final granular material of cellulose acetate.

[0158] The beneficial effects are that the drying operation is controlled by a preset target moisture threshold. Moisture data is continuously collected throughout the process to form a complete sequence and the drying endpoint is determined one by one. This can accurately control the moisture content of the powder and effectively prevent the material from being under-dryed or over-dried, which would damage the original properties of the material. By comprehensively detecting and obtaining the overall particle size distribution data of the dried powder and classifying it according to the target particle size range, materials with different particle size states are categorized and returned to the corresponding crushing area for reprocessing. This not only strictly controls the particle size quality of the final product, but also enables the recycling and reprocessing of unqualified materials, reducing raw material loss. The entire drying, grading and recirculation process is highly automated and the process is seamless, which greatly improves the finished product qualification rate and overall production efficiency of cellulose acetate granular materials.

[0159] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0160] This application embodiment can acquire and process relevant data based on artificial intelligence technology. Artificial intelligence is the theory, method, technology, and application system that uses digital computers or machines controlled by digital computers to simulate, extend, and expand human intelligence, perceive the environment, acquire knowledge, and use that knowledge to obtain optimal results.

[0161] Finally, 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 method for preparing granular cellulose acetate based on two-stage precipitation and pulverization, characterized in that, The method includes: A. Inject the cellulose acetate solution to be treated into a precipitation container containing a precipitation medium, and simultaneously collect real-time viscosity data of the mixture in the precipitation container; B. Based on the real-time viscosity data, adjust the replenishment flow rate of the precipitation medium and the injection flow rate of the solution to be treated to obtain the initial precipitated cellulose acetate particle suspension; C. Monitor the cumulative particle size distribution data of the particles in the initial sedimentation particle suspension, and control the processing intensity of the first-stage crushing zone based on the comparison result between the cumulative particle size distribution data and the preset first size threshold to obtain the coarsely crushed cellulose acetate material. D. The solid phase in the coarsely pulverized material is subjected to displacement washing to obtain the washed wet granules of cellulose acetate; E. The washed wet particles are conveyed to the second-stage crushing treatment zone, where auxiliary medium carrier gas is introduced and the instantaneous particle size data of the material at the outlet of the second-stage crushing treatment zone is monitored in real time. F. Perform a difference analysis between the instantaneous particle size data and the target particle size range of cellulose acetate to obtain the particle size deviation value of cellulose acetate, and adjust the flow rate and ratio of the auxiliary medium carrier gas according to the particle size deviation value to obtain finely pulverized cellulose acetate powder. G. The finely pulverized powder is dried, and the dried powder is graded to obtain the final granular material of cellulose acetate.

2. The method for preparing granular cellulose acetate based on two-stage precipitation and pulverization as described in claim 1, characterized in that, The step of injecting the cellulose acetate solution to be treated into a precipitation container containing a precipitation medium, and simultaneously collecting real-time viscosity data of the mixture within the precipitation container, includes: According to the preset injection flow rate, the cellulose acetate solution to be treated is injected at a uniform rate into the precipitation container containing the precipitation medium. During the uniform injection process, the instantaneous viscosity values ​​of the mixture in the precipitation vessel are continuously recorded to obtain the original viscosity sequence of the mixture. Linear interpolation is performed on the outliers in the original viscosity sequence to obtain the intermediate viscosity sequence of the mixture; The intermediate viscosity sequence is numerically smoothed to obtain the real-time viscosity data of the mixture.

3. The method for preparing granular cellulose acetate based on two-stage precipitation and pulverization as described in claim 1, characterized in that, The step of adjusting the replenishment flow rate of the precipitation medium and the injection flow rate of the solution to be treated based on the real-time viscosity data to obtain the initial precipitated cellulose acetate particle suspension includes: The real-time viscosity data is compared with the preset target viscosity range to obtain the precipitation control scheme of cellulose acetate. When the real-time viscosity data is higher than the upper limit of the target viscosity range, increase the replenishment flow rate of the precipitation medium and simultaneously decrease the injection flow rate of the solution to be treated. When the real-time viscosity data is lower than the lower limit of the target viscosity range, the replenishment flow rate of the precipitation medium is reduced while the injection flow rate of the solution to be treated is increased. When the real-time viscosity data is within the target viscosity range, the replenishment flow rate of the precipitation medium and the injection flow rate of the solution to be treated are kept constant. According to the precipitation control scheme, the solution to be treated is continuously injected to obtain the initial precipitated cellulose acetate particle suspension.

4. The method for preparing granular cellulose acetate based on two-stage precipitation and pulverization as described in claim 1, characterized in that, The cumulative particle size distribution data of the particles in the initial sedimentation particle suspension is monitored, and the processing intensity of the first-stage pulverization zone is controlled based on the comparison between the cumulative particle size distribution data and a preset first size threshold to obtain the coarsely pulverized cellulose acetate material, comprising: Obtain a particle size test sample of the initial sedimentation particle suspension to obtain particle size data of the particle size test sample; The cumulative integral transform of the particle size data is performed to obtain the cumulative particle size distribution data of the particle size detection sample; The cumulative particle size distribution data is parameterized and mapped to a preset first size threshold to obtain representative particle size data of the particle size detection sample; Based on the representative particle size data and the first size threshold, a first-stage pulverization treatment zone control command for the cellulose acetate is generated, and the first-stage pulverization treatment zone control command is responded to to obtain coarsely pulverized cellulose acetate material.

5. The method for preparing granular cellulose acetate based on two-stage precipitation and pulverization as described in claim 4, characterized in that, The step of generating a first-stage pulverization zone control command for the cellulose acetate based on the representative particle size data and the first size threshold, and responding to the first-stage pulverization zone control command to obtain coarsely pulverized cellulose acetate material, includes: When the representative particle size data is greater than the first size threshold, the processing intensity of the first-stage crushing zone is increased to obtain an enhanced control command for the first-stage crushing zone. When the representative particle size data is smaller than the first size threshold, the processing intensity of the first-stage crushing processing zone is reduced, and a reduction control command for the first-stage crushing processing zone is obtained. When the representative particle size data is equal to the first size threshold, the processing intensity of the first-stage crushing processing zone is kept constant, and a stable control command for the first-stage crushing processing zone is obtained. Based on the enhanced control command, the reduced control command, and the stable control command, the particles in the initial sedimentation particle suspension are subjected to a first-stage crushing process to obtain the coarsely crushed cellulose acetate material.

6. The method for preparing granular cellulose acetate based on two-stage precipitation and pulverization as described in claim 1, characterized in that, The process of displacement washing of the solid phase in the coarsely pulverized material to obtain washed wet granules of cellulose acetate includes: The coarsely pulverized material is subjected to solid-liquid separation to obtain the solid phase of the coarsely pulverized material; The solid phase is subjected to displacement washing using a washing medium, and real-time index data of the washing waste liquid is continuously collected during the displacement washing process to obtain the waste liquid monitoring sequence of the solid phase. The index values ​​in the waste liquid monitoring sequence are compared one by one with the preset washing endpoint threshold to obtain the washed wet granules of cellulose acetate.

7. The method for preparing granular cellulose acetate based on two-stage precipitation and pulverization as described in claim 1, characterized in that, The step involves performing a difference analysis between the instantaneous particle size data and the target particle size range of cellulose acetate to obtain the particle size deviation value of the cellulose acetate. Based on the particle size deviation value, the flow rate and ratio of the auxiliary medium carrier gas are adjusted to obtain finely pulverized cellulose acetate powder, comprising: The instantaneous particle size data is weighted and averaged to obtain the weighted representative particle size value of the material. Obtain the geometric center value of the target particle size range in the cellulose acetate, and perform normalized difference between the weighted representative particle size value and the geometric center value to obtain the relative deviation rate of the cellulose acetate. The adjustment coefficient of the auxiliary medium carrier gas is calculated based on the relative deviation rate. Multiply the adjustment coefficient by the current flow rate of the auxiliary medium carrier gas to obtain the target flow rate of the auxiliary medium carrier gas; The target ratio of the auxiliary medium carrier gas is obtained by performing a scalar multiplication transformation on the adjustment coefficient and the current ratio of the auxiliary medium carrier gas. Based on the target flow rate and the target ratio, the washed wet particles are subjected to a second-stage pulverization process to obtain finely pulverized cellulose acetate powder.

8. The method for preparing granular cellulose acetate based on two-stage precipitation and pulverization as described in claim 7, characterized in that, The formula for calculating the adjustment coefficient is as follows: ； in, This represents the adjustment coefficient. This represents the preset single adjustment coefficient. This represents the relative deviation rate. Represents the natural constant.

9. The method for preparing granular cellulose acetate based on two-stage precipitation and pulverization as described in claim 1, characterized in that, The process of drying the finely pulverized powder and classifying the dried powder to obtain the final granular material of cellulose acetate includes: Based on the target moisture threshold of cellulose acetate, the finely pulverized powder is dried, and real-time moisture content data of the finely pulverized powder is continuously collected during the drying process to obtain the moisture content sequence of the finely pulverized powder. The values ​​in the moisture content sequence are compared with the target moisture threshold one by one to obtain the dried cellulose acetate powder. Obtain the overall particle size distribution data of the dried powder, and determine the classification of the overall particle size distribution data with the target particle size range to obtain the final granular material of cellulose acetate.

10. The method for preparing granular cellulose acetate based on two-stage precipitation and pulverization as described in claim 9, characterized in that, The step of determining the attribution of the overall particle size distribution data to the target particle size range to obtain the final granular material of cellulose acetate includes: If the overall particle size distribution data is higher than the upper limit of the target particle size range, the dried powder is marked as coarse powder to be returned and the dried powder is returned to the first-stage crushing processing area. If the overall particle size distribution data is lower than the lower limit of the target particle size range, the dried powder is marked as fine powder to be returned and the dried powder is returned to the second-stage crushing processing area. If the overall particle size distribution data is within the target particle size range, the dried powder is marked as qualified powder, and the final granular material of cellulose acetate is obtained.

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