A method and device for detecting the sealing performance of a precision filter

Abstract

The present application relates to the technical field of pipeline noise elimination, and in particular to a precision filter sealing detection method and device, which collects air pressure during pressure increase and pressure maintenance at different temperature levels, determines real air pressure sequence, standard air pressure sequence, pressure increase time period and pressure maintenance time period of the same temperature level, determines temperature influence degree of the precision filter, divides leak sub-time periods from the pressure increase time period and the pressure maintenance time period respectively, determines intermittent leakage degree corresponding to the same temperature level according to the duration of all leak sub-time periods divided from the same temperature level, the duration of the pressure increase time period and the pressure maintenance time period, and completes sealing detection of the precision filter in combination with the difference between all temperature levels and actual temperature of the precision filter sealing detection and the temperature influence degree of the precision filter. The present application can improve the accuracy of precision filter sealing detection.

Description

Technical Field

[0001] This invention relates to the field of pipeline noise reduction technology, specifically to a method and apparatus for testing the sealing performance of a precision filter. Background Technology

[0002] Microcrystalline cellulose is produced from natural wood or plant fibers through acid hydrolysis. It undergoes multiple washings with water or alcohol solvents, followed by filtration using a precision filter to remove fine particles and undissolved substances. This process removes impurities and acidic residues from the hydrolysis process, ensuring the purity of the microcrystalline cellulose. The airtightness of the precision filter is crucial to the purity of the resulting microcrystalline cellulose; therefore, the airtightness of the precision filter must be tested.

[0003] Currently, precision filters are typically pressurized and held at pressure, with the filter's seal assessed by observing a continuous drop in pressure during the holding phase. However, some poorly sealed precision filters only exhibit intermittent pressure instability during the holding phase, and existing precision filter seal testing methods are not sensitive to filters exhibiting this condition. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method and apparatus for detecting the sealing performance of a precision filter, the specific technical solution of which is as follows:

[0005] In a first aspect, one embodiment of the present invention provides a method for detecting the sealing performance of a precision filter, the method comprising the following steps:

[0006] During the pressurization and pressure holding process at a preset number of temperature levels, the air pressure at different sampling times is collected. Based on all the air pressures collected at the same temperature level, the actual air pressure sequence, standard air pressure sequence, pressurization time period, and pressure holding time period for the same temperature level are determined.

[0007] The temperature influence of the precision filter is determined based on the difference between the real pressure sequence and the standard pressure sequence at the same temperature level across all temperature grades.

[0008] Based on the pressure difference between all adjacent sampling times within the pressurization period of the same temperature level, leakage sub-time periods are divided. Based on the pressure difference between all adjacent sampling times within the pressure holding period of the same temperature level, leakage sub-time periods are divided from the pressure holding period. Based on the duration of all leakage sub-time periods divided within the same temperature level, the duration of the pressurization period, and the duration of the pressure holding period, the degree of intermittent leakage corresponding to the same temperature level is determined.

[0009] The precision filter's sealing performance is tested based on the differences between all temperature ratings and the actual temperatures used for the precision filter's sealing performance test, the degree of intermittent leakage corresponding to each temperature rating, and the temperature influence of the precision filter.

[0010] Furthermore, the method for determining the actual pressure sequence, standard pressure sequence, pressurization time period, and pressure holding time period at the same temperature level is as follows:

[0011] All air pressures collected at the same temperature level are arranged in chronological order of collection time to obtain the true air pressure sequence at the same temperature level.

[0012] Establish a Cartesian coordinate system with the time of data collection as the x-axis and air pressure as the y-axis. The point corresponding to the earliest collected air pressure in the Cartesian coordinate system is designated as the first standard point. The point corresponding to the earliest collected air pressure that is greater than or equal to the preset holding pressure is designated as the second standard point. The collection time corresponding to the second standard point is designated as the standard holding pressure time. The straight line passing through the first and second standard points in the Cartesian coordinate system is designated as the standard air pressure line. The time period from the earliest collection time to the standard holding pressure time is designated as the pressurization time period. The time period from the standard holding pressure time to the latest collection time is designated as the holding pressure time period.

[0013] The pressure values ​​corresponding to the standard pressure line at all sampling times during the pressurization period are recorded as the standard pressure at the sampling time. The standard pressure at all sampling times during the pressure holding period is assigned a preset pressure holding value. All standard pressures are arranged in chronological order of sampling times to obtain the standard pressure sequence.

[0014] Furthermore, the method for obtaining the temperature influence of the precision filter is as follows:

[0015] The DTW distance between the real pressure series and the standard pressure series at the same temperature level is denoted as the absolute difference between the real pressure series and the standard pressure series at the same temperature level.

[0016] The temperature influence of the precision filter is determined based on the absolute difference between the real and standard pressure sequences for all temperature levels, using the following formula:

[0017]

[0018] In the formula, A represents the temperature influence of the precision filter; t1 represents the first preset threshold; H k H represents the absolute difference between the true pressure sequence and the standard pressure sequence at the k-th temperature level; k-1 This represents the absolute difference between the true pressure sequence and the standard pressure sequence at the (k-1)th temperature level.

[0019] Furthermore, the specific method for dividing the leakage sub-time period based on the pressure difference between all adjacent sampling times within a pressurization time period at the same temperature level includes:

[0020] Any sampling time included within the pressurization period is recorded as the target pressurization sampling time. The absolute value of the pressure difference between the target pressurization sampling time and the previous adjacent sampling time is recorded as the adjacent pressure difference of the target pressurization sampling time.

[0021] The rate of change of air pressure at the target pressurization sampling time is determined based on the adjacent air pressure difference at the target pressurization sampling time, the total volume inside the precision filter, and the time interval between adjacent sampling times. The rate of change of air pressure at the target pressurization sampling time is positively correlated with the adjacent air pressure difference at the target pressurization sampling time and the total volume inside the precision filter, and negatively correlated with the time interval between adjacent sampling times.

[0022] Density clustering is performed on the rate of pressure change of all sampling moments within the pressurization time period of the same temperature level to obtain clusters. The time period consisting of adjacent sampling moments within the same cluster is recorded as a sub-time period of the pressurization time period.

[0023] Based on the air pressure at the time of collection within the sub-time period and the duration of the sub-time period, leakage sub-time periods are divided from the sub-time period.

[0024] Furthermore, the specific method for dividing the leakage sub-time period from the sub-time period based on the air pressure collected at the sub-time period and the duration of the sub-time period includes:

[0025] Based on the rate of pressure change, pressure, duration of the sub-time period, and pressurization rate at adjacent sampling times within the sub-time period, the degree of abnormal leakage in the sub-time period is determined using the following formula:

[0026]

[0027] In the formula, E u Indicates the degree of abnormal leakage in sub-time period u; r u Q represents the number of data collection times contained in the sub-time period u; x,u Q represents the rate of change of air pressure at the x-th sampling time point contained in the sub-time period u; x-1,u Δt represents the rate of change of air pressure at the (x-1)th sampling time within the sub-time period u; u Δp represents the duration of the sub-time period u; u This represents the pressure difference between the first and last sampling moments of sub-time period u; v represents the pressurization rate; norm() represents the normalization function;

[0028] The sub-time period with an abnormal leakage level greater than or equal to the second preset threshold is recorded as the leakage sub-time period.

[0029] Furthermore, the specific method for dividing the leakage sub-time period from the pressure holding time period based on the pressure difference between all adjacent sampling times within the same temperature level pressure holding time period includes:

[0030] Any sampling time included within the pressure holding period is recorded as the target pressure holding sampling time. When the air pressure of the target pressure holding sampling time is not equal to the air pressure of the sampling time adjacent to the previous target pressure holding sampling time, the target pressure holding sampling time is recorded as the leakage time. The time period consisting of consecutive leakage times within the pressure holding period is recorded as the leakage sub-time period.

[0031] Furthermore, the method for obtaining the degree of intermittent leakage corresponding to the same temperature level is as follows:

[0032] For the same temperature level, the ratio of the sum of the durations of all leakage sub-time periods divided within the pressurization period to the duration of the pressurization period is denoted as the first leakage time ratio of the pressurization period.

[0033] The ratio of the sum of the durations of all leakage sub-time periods divided within the pressure holding period to the duration of the pressure holding period is denoted as the second leakage time ratio of the pressurization period.

[0034] The time it takes for the precision filter to be pressurized at a preset pressurization rate until it reaches a preset holding pressure is recorded as the standard pressurization time. The difference between the duration of the pressurization period and the standard pressurization time is recorded as the leakage effect duration.

[0035] The product of the first leakage time ratio, the second leakage time ratio, and the leakage impact duration for the same temperature level is denoted as the intermittent leakage degree for the same temperature level.

[0036] Furthermore, the specific method for completing the precision filter's sealing test based on the differences between all temperature levels and the actual temperature of the precision filter's sealing performance test, the degree of intermittent leakage corresponding to each temperature level, and the temperature influence of the precision filter includes:

[0037] Any temperature level is designated as the target temperature level. The absolute value of the difference between the target temperature level and the actual temperature of the precision filter sealing test is designated as the absolute temperature difference of the target temperature level. The ratio of the sum of the absolute temperature differences of all temperature levels to the absolute temperature difference of the target temperature level is designated as the absolute temperature difference weight of the target temperature level.

[0038] The absolute temperature difference weight of the temperature level is used as the weight of the intermittent leakage degree corresponding to the temperature level. The intermittent leakage degree corresponding to all temperature levels is weighted and summed. The normalized value of the product of the weighted sum and the temperature influence degree of the precision filter is recorded as the sealing performance evaluation value of the precision filter.

[0039] Based on the sealing performance evaluation value of the precision filter, the sealing performance test of the precision filter is completed.

[0040] Furthermore, the specific method for completing the sealing performance test of the precision filter based on its sealing performance evaluation value includes:

[0041] When the sealing performance evaluation value of the precision filter is greater than the third preset threshold, the sealing performance of the precision filter is deemed to be substandard.

[0042] When the sealing performance evaluation value of the precision filter is less than or equal to the third preset threshold, the sealing performance of the precision filter is deemed to meet the standard.

[0043] Secondly, another embodiment of the present invention provides a precision filter sealing performance testing device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of the precision filter sealing performance testing method described above.

[0044] The embodiments of the present invention have at least the following beneficial effects:

[0045] When the sealing performance of a precision filter is good within the actual temperature range of the microcrystalline cellulose acid hydrolysis process and solvent cleaning process, it can be considered to have good sealing performance. This application presets different temperature levels, and collects air pressure during the pressurization and holding processes at each temperature level. Based on the difference between the collected air pressure and the ideal air pressure for uniformly pressurizing the precision filter, the influence of temperature on the sealing performance of the precision filter is analyzed, and the temperature influence degree of the precision filter is obtained. Furthermore, the rate of increase of air pressure and the trend of low air pressure change during the pressurization and holding processes are analyzed to divide the leakage sub-time periods, and the probability of leakage and the degree of abnormal leakage within the leakage sub-time periods are evaluated to obtain the intermittent leakage degree corresponding to each temperature level. Finally, based on the differences between all temperature levels and the actual temperature for precision filter sealing performance testing, the intermittent leakage degree corresponding to each temperature level, and the temperature influence degree of the precision filter, the sealing performance test of the precision filter is completed. This solves the problem of insensitivity to the sealing performance test of precision filters that experience intermittent air pressure instability during the holding stage, and improves the accuracy of precision filter sealing performance testing. Attached Figure Description

[0046] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are 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.

[0047] Figure 1 A flowchart illustrating the steps of a precision filter sealing performance testing method according to an embodiment of the present invention;

[0048] Figure 2 This is a flowchart illustrating the process of obtaining the rate of air pressure change according to an embodiment of the present invention. Detailed Implementation

[0049] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a precision filter sealing performance testing method and apparatus according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0051] The following description, in conjunction with the accompanying drawings, details the specific scheme of the precision filter sealing performance testing method and apparatus provided by the present invention.

[0052] Please see Figure 1 The diagram illustrates a flowchart of a precision filter sealing performance testing method according to an embodiment of the present invention, which includes the following steps:

[0053] Step S001: During the pressurization and pressure holding process at a preset number of temperature levels, collect air pressure at different collection times. Based on all the air pressures collected at the same temperature level, determine the actual air pressure sequence, standard air pressure sequence, pressurization time period, and pressure holding time period for the same temperature level.

[0054] In the process of producing microcrystalline cellulose from natural wood or plant fibers through acid hydrolysis, a precision filter is used to remove fine particles and undissolved substances from the washing process. This removes impurities and acidic residues from the acid hydrolysis process. At this time, it is necessary to preset the temperature in advance to increase the reaction temperature in the solution during filtration. At the same time, it is necessary to avoid inaccurate precision filter sealing tests due to temperature effects.

[0055] This implementation sets t1 temperature levels, and pressurizes and holds the precision filter at each temperature level to test its sealing performance. Specifically, the precision filter is placed on a support plate, and an electric push rod drives a pneumatic assembly to automatically clamp and seal both ends of the filter. The ambient temperature of the environment where the precision filter is located is raised to the corresponding temperature level. After the ambient temperature stabilizes at the corresponding temperature level, the precision filter is pressurized at a rate of 0.4 MPa / s until it reaches the preset holding pressure, which is held for 1 minute.

[0056] Wherein, t1 is the first preset threshold. In this embodiment, the value of the first preset threshold is 4, and the four temperature levels are set as 35℃, 50℃, 65℃ and 80℃ respectively. In this embodiment, the optimal pressure of the internal solution reaction during the filtration process of the precision filter is used as the preset holding pressure.

[0057] From the moment pressurization begins, a differential pressure sensor is used to collect the air pressure inside the precision filter every 0.5 seconds until the pressure holding period ends.

[0058] All air pressures collected at the same temperature level are arranged in chronological order of collection time to obtain the true air pressure sequence at the same temperature level.

[0059] It is understandable that for each temperature level, there is a corresponding real pressure sequence. Since there are t1 temperature levels, there are a total of t1 real pressure sequences, and the real pressure sequences and temperature levels correspond one-to-one.

[0060] Furthermore, a standard pressure sequence is obtained based on the pressure contained in the real pressure sequence and the preset holding pressure.

[0061] Establish a Cartesian coordinate system with the time of data collection as the x-axis and air pressure as the y-axis. The point corresponding to the earliest collected air pressure in the Cartesian coordinate system is designated as the first standard point. The point corresponding to the earliest collected air pressure that is greater than or equal to the preset holding pressure is designated as the second standard point. The collection time corresponding to the second standard point is designated as the standard holding pressure time. The straight line passing through the first and second standard points in the Cartesian coordinate system is designated as the standard air pressure line. The air pressure values ​​corresponding to all collection times between the earliest collection time and the standard holding pressure time are designated as the standard air pressure at that collection time. The standard air pressures at all collection times after the standard holding pressure time are assigned the preset holding pressure. All standard air pressures are arranged in chronological order of collection time to obtain a standard air pressure sequence.

[0062] Among them, the time period from the earliest acquisition time to the standard holding time includes both the earliest acquisition time and the standard holding time.

[0063] It is understandable that each real pressure sequence can determine a standard pressure sequence. Since there is a one-to-one correspondence between real pressure sequences and temperature levels, each temperature level corresponds to a real pressure sequence and also to a standard pressure sequence.

[0064] The time period from the earliest data acquisition time to the standard pressure holding time is recorded as the pressurization time period, and the time period from the standard pressure holding time to the latest data acquisition time is recorded as the pressure holding time period.

[0065] At this point, the actual air pressure sequence, standard air pressure sequence, pressurization period, and pressure holding period have been obtained.

[0066] Step S002: Determine the temperature influence of the precision filter based on the difference between the actual pressure sequence and the standard pressure sequence at the same temperature level across all temperature levels.

[0067] To avoid inaccuracies in precision filter sealing tests due to temperature effects, the differences between the actual pressure series and the standard pressure series at each temperature level were compared to analyze the impact of temperature on precision filter sealing.

[0068] Because the pressurization rate of the precision filter is constant, when the precision filter is completely sealed, the internal air pressure should increase at a fixed rate. Specifically, during the pressurization period, the standard air pressure at each sampling moment increases at a fixed rate sequentially from morning to night, while during the pressure holding period, the standard air pressure remains unchanged at each sampling moment. Therefore, the smaller the difference between the actual air pressure sequence and the standard air pressure sequence at the same temperature level, the smaller the impact of temperature on the sealing performance of the precision filter.

[0069] The temperature influence of the precision filter is determined based on the difference between the actual pressure sequence and the standard pressure sequence at the same temperature level across all temperature grades.

[0070] The DTW distance between the real pressure series and the standard pressure series at the same temperature level is denoted as the absolute difference between the real pressure series and the standard pressure series at the same temperature level.

[0071] The temperature influence of the precision filter is determined based on the absolute difference between the true and standard pressure sequences for all temperature levels. Specifically, the formula for calculating the temperature influence of the precision filter is:

[0072]

[0073] In the formula, A represents the temperature influence of the precision filter; t1 represents the first preset threshold; H k H represents the absolute difference between the true pressure sequence and the standard pressure sequence at the k-th temperature level; k-1 This represents the absolute difference between the true pressure sequence and the standard pressure sequence at the (k-1)th temperature level.

[0074] The first temperature level is 35℃, the second temperature level is 50℃, the third temperature level is 65℃, and the fourth temperature level is 80℃. In this embodiment, the first preset threshold value is 4. The calculation of the DTW distance between the real pressure sequence and the standard pressure sequence is a well-known technique and will not be described in detail here.

[0075] The temperature effect of a precision filter evaluates the degree to which an increase in temperature affects the filter's sealing performance. The greater the difference between the actual pressure series and the standard pressure series at the same temperature level, the greater the absolute difference, and the more severe the leakage of the precision filter at that temperature level. Furthermore, the greater the difference between the actual pressure series and the standard pressure series at the same temperature level across all temperature levels, the more severe the leakage of the precision filter at each temperature level, and the greater the impact of temperature increase on the precision filter's sealing performance. In this case, the temperature effect of the precision filter is greater.

[0076] Thus, the temperature influence of the precision filter is obtained.

[0077] Step S003: Based on the pressure difference between all adjacent sampling times within the pressurization time period of the same temperature level, divide the leakage sub-time period. Based on the pressure difference between all adjacent sampling times within the pressure holding time period of the same temperature level, divide the leakage sub-time period from the pressure holding time period. Based on the duration of all leakage sub-time periods divided within the same temperature level, the duration of the pressurization time period, and the duration of the pressure holding time period, determine the degree of intermittent leakage corresponding to the same temperature level.

[0078] Leakage may occur during the pressurization and pressure holding processes of a precision filter. When the precision filter is not properly sealed, the air pressure inside the filter will exhibit different characteristics during pressurization and pressure holding. Therefore, it is necessary to analyze the pressurization and pressure holding processes separately.

[0079] Based on the air pressure at all sampling times within the pressurization period of the same temperature level, the pressurization period is divided into sub-periods.

[0080] For any given temperature level and pressurization period, when the precision filter is completely sealed, the air pressure at different sampling times within the pressurization period should increase at a fixed rate. When intermittent air pressure instability occurs, the rate of air pressure increase will change.

[0081] Any sampling time within the pressurization period is recorded as the target pressurization sampling time. The absolute value of the pressure difference between the target pressurization sampling time and the previous adjacent sampling time is recorded as the adjacent pressure difference of the target pressurization sampling time.

[0082] The rate of change of air pressure at the target pressurization sampling time is determined based on the adjacent air pressure difference at the target pressurization sampling time, the total volume inside the precision filter, and the time interval between adjacent sampling times. The rate of change of air pressure at the target pressurization sampling time is positively correlated with the adjacent air pressure difference at the target pressurization sampling time and the total volume inside the precision filter, and negatively correlated with the time interval between adjacent sampling times.

[0083] The product of the adjacent pressure difference at the target pressurization sampling time and the total volume inside the precision filter is recorded as the first product at the target pressurization sampling time. The ratio of the first product at the target pressurization sampling time to the time interval between adjacent sampling times is recorded as the pressure change rate at the target pressurization sampling time.

[0084] The same method can be used to obtain the rate of pressure change at any sampling moment within the pressurization period. In other words, each sampling moment within the pressurization period has a corresponding rate of pressure change. The flowchart for obtaining the rate of pressure change is as follows: Figure 2 As shown.

[0085] It is understood that the positive and negative correlations in this application refer to the relationship between the independent and dependent variables. A positive correlation means that the dependent variable increases (decreases) as the independent variable increases (decreases), and can be an additive or multiplicative relationship. A negative correlation means that the dependent variable decreases (increases) as the independent variable increases (decreases), and can be an inverse relationship or a subtractive relationship.

[0086] Understandably, the earliest sampling time has no preceding adjacent sampling time, so the pressure change rate is not calculated for the earliest sampling time. When the precision filter is completely sealed, the pressure at different sampling times within the pressurization period should increase at a fixed rate, and the pressure change rate at each sampling time within the pressurization period of the same temperature level should be the same.

[0087] Density clustering is performed on the pressure change rates at all sampling times within a pressurization period of the same temperature level to obtain clusters. The time interval consisting of adjacent sampling times within the same cluster is denoted as a sub-time interval of the pressurization period. Thus, the pressurization period of the same temperature level is divided into sub-time intervals based on the pressure change rates at all sampling times within the pressurization period of the same temperature level.

[0088] In some embodiments of this application, the DBSCAN clustering algorithm is used to cluster the rate of air pressure change. In practical applications, as other implementation methods, implementers may also use other density clustering methods such as X-means and HDBSCAN in the prior art, and automatically obtain the number of clusters during the process of obtaining clusters.

[0089] Leaking sub-time periods are selected based on the rate of change of air pressure, air pressure, duration of the sub-time period, and pressurization rate at adjacent sampling times within the sub-time period.

[0090] First, based on the rate of change of air pressure, air pressure, duration of the sub-time period, and pressurization rate at adjacent sampling times within the sub-time period, the degree of abnormal leakage in the sub-time period is determined. The calculation formula is as follows:

[0091]

[0092] In the formula, E u Indicates the degree of abnormal leakage in sub-time period u; r u Q represents the number of data collection times contained in the sub-time period u; x,u Q represents the rate of change of air pressure at the x-th sampling time point contained in the sub-time period u; x-1,u Δt represents the rate of change of air pressure at the (x-1)th sampling time within the sub-time period u; u This represents the duration of the sub-time period u, specifically the time elapsed from the first acquisition moment to the last acquisition moment of sub-time period u; Δp u The pressure difference between the first and last sampling times of sub-time period u is represented by v; the pressurization rate is constant in this embodiment at 0.4 MPa / s; norm() represents the normalization function, which is used to avoid the influence of dimensions.

[0093] It should be noted that this embodiment uses the Z-Score standard normalization method to calculate the normalized value corresponding to the normalization function. In practical applications, implementers may use other methods of existing technology, such as the maximum-minimum normalization method or the sigmoid function, to calculate the normalized value corresponding to the normalization function. No limitation is made here.

[0094] The greater the difference in the rate of pressure change between adjacent sampling moments within a sub-time period, the greater the difference in pressure between the first and last sampling moments of the sub-time period, and the greater the difference between the time required to pressurize the pressure difference appearing in the sub-time period at the pressurization rate and the duration of the sub-time period, the greater the possibility of leakage occurring within the sub-time period. In this case, the degree of abnormal leakage in the sub-time period is greater.

[0095] The sub-time period with an abnormal leakage level greater than or equal to the second preset threshold is recorded as the leakage sub-time period.

[0096] In this embodiment, the value of the second preset threshold is 0.8.

[0097] When the precision filter is completely sealed, the air pressure should be exactly the same at different sampling times within the pressure holding period. Therefore, based on the difference in air pressure between all adjacent sampling times within the pressure holding period of the same temperature level, the leakage sub-period is divided from the pressure holding period.

[0098] Any sampling time included within the pressure holding period is recorded as the target pressure holding sampling time. When the air pressure of the target pressure holding sampling time is not equal to the air pressure of the sampling time adjacent to the previous target pressure holding sampling time, the target pressure holding sampling time is recorded as the leakage time. The time period consisting of consecutive leakage times within the pressure holding period is recorded as the leakage sub-time period.

[0099] It is important to note that each temperature level has a corresponding pressurization period and a pressure holding period. The leakage sub-period is divided from the pressurization period or the pressure holding period. Therefore, each leakage sub-period has a corresponding temperature level.

[0100] The degree of intermittent leakage corresponding to the same temperature level is determined by the duration of all leakage sub-time periods, the duration of pressurization time periods and the duration of pressurization of the precision filter at a preset pressurization rate until the precision filter reaches the preset holding pressure.

[0101] For the same temperature level, the ratio of the sum of the durations of all leakage sub-time periods divided within the pressurization period to the total duration of the pressurization period is recorded as the first leakage time ratio of the pressurization period; the ratio of the sum of the durations of all leakage sub-time periods divided within the pressure holding period to the total duration of the pressure holding period is recorded as the second leakage time ratio of the pressurization period; the time taken to pressurize the precision filter using a preset pressurization rate until the precision filter reaches the preset pressure holding pressure is recorded as the standard pressurization time; and the difference between the duration of the pressurization period and the standard pressurization time is recorded as the leakage effect duration.

[0102] The degree of intermittent leakage corresponding to the same temperature level is determined based on the first leakage time ratio, the second leakage time ratio, and the leakage impact duration during the pressurization period corresponding to the same temperature level. The first leakage time ratio, the second leakage time ratio, and the leakage impact duration during the pressurization period corresponding to the same temperature level are positively correlated with the degree of intermittent leakage corresponding to the same temperature level.

[0103] The product of the first leakage time ratio, the second leakage time ratio, and the leakage impact duration for the same temperature level is denoted as the intermittent leakage degree for the same temperature level.

[0104] Preferably, as an embodiment of this application, the smaller the sum of the durations of all leakage sub-time periods divided within the pressurization period compared to the total duration of the pressurization period, the smaller the sum of the durations of all leakage sub-time periods divided within the pressure holding period compared to the total duration of the pressure holding period, and the closer the duration of the pressurization period is to the standard pressurization period, the lower the probability of leakage in the precision filter, the less obvious the degree of leakage, and the better the sealing performance of the precision filter. In this case, the degree of intermittent leakage corresponding to the same temperature level is smaller.

[0105] It is understood that each temperature level corresponds to a degree of intermittent leakage. Since this embodiment sets four temperature levels, a total of four degrees of intermittent leakage are obtained, and each degree of intermittent leakage has a corresponding temperature level.

[0106] This allows us to obtain the degree of intermittent leakage corresponding to each temperature level.

[0107] Step S004: Based on the differences between all temperature levels and the actual temperature of the precision filter sealing test, the degree of intermittent leakage corresponding to each temperature level, and the temperature influence of the precision filter, the sealing test of the precision filter is completed.

[0108] It is important to note that the acid hydrolysis and solvent cleaning processes of microcrystalline cellulose are conducted at a constant temperature. As long as the precision filter maintains a high level of sealing at this constant temperature, its sealing performance will not significantly affect the production quality of microcrystalline cellulose. In other words, if the precision filter's sealing performance is good within the actual temperature range of the acid hydrolysis and solvent cleaning processes, then the precision filter can be considered to have good sealing performance. Therefore, based on the differences between the actual temperature of the solvent cleaning process and each temperature level, the degree of intermittent leakage at each temperature level is determined to influence the sealing performance of the precision filter.

[0109] The actual temperature of the acid hydrolysis process and solvent cleaning process of microcrystalline cellulose is generally 80-100℃. In this embodiment, 90℃ is selected as the actual temperature for the precision filter sealing test.

[0110] The sealing performance evaluation value of the precision filter is determined based on the difference between all temperature levels and the actual temperature of the precision filter sealing test, the degree of intermittent leakage corresponding to each temperature level, and the temperature influence of the precision filter.

[0111] Any temperature level is designated as the target temperature level. The absolute value of the difference between the target temperature level and the actual temperature of the precision filter sealing test is designated as the absolute temperature difference of the target temperature level. The ratio of the sum of the absolute temperature differences of all temperature levels to the absolute temperature difference of the target temperature level is designated as the absolute temperature difference weight of the target temperature level.

[0112] The absolute temperature difference weight for any temperature level can be obtained using the same method; that is, each temperature level has a corresponding absolute temperature difference weight.

[0113] The absolute temperature difference weight of the temperature level is used as the weight of the intermittent leakage degree corresponding to the temperature level. The intermittent leakage degree corresponding to all temperature levels is weighted and summed. The normalized value of the product of the weighted sum and the temperature influence degree of the precision filter is recorded as the sealing performance evaluation value of the precision filter.

[0114] The smaller the absolute temperature difference of the target temperature rating, the smaller the difference between the target temperature rating and the actual temperature of the precision filter's sealing performance test. This makes using the target temperature rating to evaluate the precision filter's sealing performance more accurate. In this case, the weight of the absolute temperature difference of the target temperature rating is greater. Furthermore, the more accurate the result of weighted summation, where the absolute temperature difference weight of the temperature rating is used as the weight for the degree of intermittent leakage corresponding to that temperature rating. A higher sealing performance evaluation value for the precision filter indicates more significant intermittent leakage and poorer sealing performance.

[0115] It should be noted that this embodiment uses the Z-Score standard normalization method to calculate the normalized value. In practical applications, implementers may use other methods of existing technology, such as the maximum-minimum normalization method or the sigmoid function, to calculate the normalized value, and no limitation is made here.

[0116] When the sealing performance evaluation value of the precision filter is greater than the third preset threshold, the precision filter is determined to be substandard and the precision filter is replaced; when the sealing performance evaluation value of the precision filter is less than or equal to the third preset threshold, the precision filter is determined to be standard.

[0117] In this embodiment, the third preset threshold value is 0.9.

[0118] This completes the sealing test of the precision filter.

[0119] This invention also proposes a precision filter sealing performance testing device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. The processor executes the computer program to perform the steps described above. Since a precision filter sealing performance testing method has been described in detail above, it will not be repeated here.

[0120] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, the above description focuses on specific embodiments of this specification. Additionally, the processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0121] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0122] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them; modifications to the technical solutions described in the foregoing embodiments, or equivalent substitutions of some of the technical features, do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for detecting the tightness of a precision filter, characterized in that, The method comprises the following steps: During the process of pressurization and pressure maintenance at a preset number of temperature levels, the air pressure at different collection time points is collected, and according to all the air pressures collected at the same temperature level, the real air pressure sequence, the standard air pressure sequence, the pressurization time period and the pressure maintenance time period of the same temperature level are determined; According to the difference between the real air pressure sequence and the standard air pressure sequence of the same temperature level in all temperature levels, the temperature influence degree of the precision filter is determined; According to the difference between the air pressures of all adjacent collection time points contained in the pressurization time period of the same temperature level, the leakage sub-time period is divided, and according to the difference between the air pressures of all adjacent collection time points contained in the pressure maintenance time period of the same temperature level, the leakage sub-time period is divided from the pressure maintenance time period, and according to the duration of all the leakage sub-time periods divided in the same temperature level, the duration of the pressurization time period and the pressure maintenance time period, the intermittent leakage degree corresponding to the same temperature level is determined; According to the difference between the actual temperature of the precision filter in the sealing detection and all temperature levels, the intermittent leakage degree corresponding to each temperature level, and the temperature influence degree of the precision filter, the sealing detection of the precision filter is completed.

2. The method of claim 1, wherein The determination method of the real air pressure sequence, the standard air pressure sequence, the pressurization time period and the pressure maintenance time period of the same temperature level is: All the air pressures collected at the same temperature level are arranged in the order of collection time points to obtain the real air pressure sequence of the same temperature level; The collection time point is taken as the abscissa, and the air pressure is taken as the ordinate to establish a plane rectangular coordinate system; the point corresponding to the air pressure collected at the earliest collection time point in the plane rectangular coordinate system is recorded as the first standard point, the point corresponding to the air pressure collected at the earliest collection time point and greater than or equal to the preset pressure maintenance pressure in all collected air pressures in the plane rectangular coordinate system is recorded as the second standard point, the collection time point corresponding to the second standard point is recorded as the standard pressure maintenance time point; the straight line passing through the first standard point and the second standard point in the plane rectangular coordinate system is recorded as the standard air pressure straight line; the time period corresponding to the earliest collection time point to the standard pressure maintenance time point is recorded as the pressurization time period; the standard pressure maintenance time point to the latest collection time point is recorded as the pressure maintenance time period; The value of the air pressure corresponding to the collection time point of the standard air pressure of all the collection time points in the pressurization time period is recorded as the standard air pressure; the standard air pressure of all the collection time points in the pressure maintenance time period is assigned as the preset pressure maintenance pressure; all the standard air pressures are arranged in the order of collection time points to obtain the standard air pressure sequence.

3. The method of claim 1, wherein The acquisition method of the temperature influence degree of the precision filter is: The DTW distance of the real air pressure sequence and the standard air pressure sequence of the same temperature level is recorded as the absolute difference between the real air pressure sequence and the standard air pressure sequence of the same temperature level; According to the absolute difference between the real air pressure sequence and the standard air pressure sequence of all temperature levels, the temperature influence degree of the precision filter is determined, and the calculation formula is: In the formula, A represents a temperature influence degree of the precision filter; t1 represents a first preset threshold; H k represents an absolute difference between the real air pressure sequence and the standard air pressure sequence of the kth temperature level; H k-1 represents an absolute difference between the real air pressure sequence and the standard air pressure sequence of the k-1th temperature level.

4. The method of claim 1, wherein The specific method for dividing the leakage sub-time period according to the difference between the air pressures of all adjacent collection time points contained in the pressurization time period of the same temperature level includes: An arbitrary one of the collection time points included in the pressurization time period is recorded as a target pressurization collection time point, and an absolute value of a difference between the pressure at the target pressurization collection time point and the pressure at a neighboring collection time point before the target pressurization collection time point is recorded as a neighboring pressure difference of the target pressurization collection time point; A pressure change rate of the target pressurization collection time point is determined according to the neighboring pressure difference of the target pressurization collection time point, the total volume inside the precision filter, and a time interval between the neighboring collection time points, and the pressure change rate of the target pressurization collection time point is positively correlated with the neighboring pressure difference of the target pressurization collection time point and the total volume inside the precision filter, and is negatively correlated with the time interval between the neighboring collection time points; Density clustering is performed on the pressure change rates of all the collection time points included in the pressurization time period of the same temperature level, a clustering cluster is obtained, and a time period formed by neighboring collection time points in the same clustering cluster is recorded as a sub time period of the pressurization time period; A leakage sub time period is divided from the sub time period according to the pressure at the collection time point in the sub time period and the length of the sub time period.

5. The method of claim 4, wherein The specific method of dividing the leakage sub time period from the sub time period according to the pressure at the collection time point in the sub time period and the length of the sub time period includes: An abnormal leakage degree of the sub time period is determined according to the pressure change rate and the pressure of the neighboring collection time points in the sub time period, the length of the sub time period, and the pressurization rate, and the calculation formula is: wherein E u represents the abnormal leakage degree of the sub-time period u; r u represents the number of collection instants included in the sub-time period u; Q x,u represents the air pressure change rate of the xth collection instant included in the sub-time period u; Q x-1,u represents the air pressure change rate of the x-1th collection instant included in the sub-time period u; Δt u represents the duration of the sub-time period u; Δp u represents the difference between the air pressure of the first collection instant and the last collection instant of the sub-time period u; v represents the pressurization rate; norm() represents the normalization function; The sub time period with the abnormal leakage degree greater than or equal to the second preset threshold value is recorded as the leakage sub time period.

6. The method of claim 1, wherein The specific method of dividing the leakage sub time period from the holding time period according to the difference between the pressures at all the neighboring collection time points included in the holding time period of the same temperature level includes: An arbitrary one of the collection time points included in the holding time period is recorded as a target holding collection time point, and when the pressure at the target holding collection time point is not equal to the pressure at a neighboring collection time point before the target holding collection time point, the target holding collection time point is recorded as a leakage time point, and a time period formed by continuous leakage time points in the holding time period is recorded as a leakage sub time period.

7. The method of claim 1, wherein The specific method of obtaining the intermittent leakage degree corresponding to the same temperature level includes: For the same temperature level, a ratio of a sum of the lengths of all the leakage sub time periods divided in the pressurization time period to the length of the pressurization time period is recorded as a first leakage time ratio of the pressurization time period; A ratio of a sum of the lengths of all the leakage sub time periods divided in the holding time period to the length of the holding time period is recorded as a second leakage time ratio of the pressurization time period; A length of time during which the precision filter is pressurized at the preset pressurization rate until the precision filter reaches the preset holding pressure is recorded as a standard pressurization length, and a difference between the length of the pressurization time period and the standard pressurization length is recorded as a leakage influence length; A product of the first leakage time ratio of the pressurization time period, the second leakage time ratio of the pressurization time period, and the leakage influence length corresponding to the same temperature level is recorded as the intermittent leakage degree corresponding to the same temperature level.

8. The method of claim 1, wherein The sealing detection of the precision filter is completed according to the difference between all temperature grades and the actual temperature of the sealing detection of the precision filter, the intermittent leakage degree corresponding to each temperature grade, and the temperature influence degree of the precision filter, and the specific method comprises the following steps: Any temperature grade is recorded as a target temperature grade, the absolute value of the difference between the target temperature grade and the actual temperature of the sealing detection of the precision filter is recorded as the absolute temperature difference of the target temperature grade, and the ratio of the cumulative sum of the absolute temperature differences of all temperature grades to the absolute temperature difference of the target temperature grade is recorded as the absolute temperature difference weight of the target temperature grade; The absolute temperature difference weight of the temperature grade is used as the weight of the intermittent leakage degree corresponding to the temperature grade, the weighted sum of the intermittent leakage degrees corresponding to all temperature grades is obtained, and the normalized value of the product of the weighted sum result and the temperature influence degree of the precision filter is recorded as the sealing evaluation value of the precision filter; The sealing detection of the precision filter is completed according to the sealing evaluation value of the precision filter.

9. The method of claim 8, wherein the method further comprises: The sealing detection of the precision filter is completed according to the sealing evaluation value of the precision filter, and the specific method comprises the following steps: When the sealing evaluation value of the precision filter is greater than a third preset threshold value, it is determined that the sealing of the precision filter is substandard; When the sealing evaluation value of the precision filter is less than or equal to the third preset threshold value, it is determined that the sealing of the precision filter is up to standard.

10. A precision filter leak detection apparatus comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein, The processor executes the computer program to realize the steps of the sealing detection method of the precision filter according to any one of claims 1-9.

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