A smart dissolved air flotation device and pressure control system

Abstract

This application relates to the field of wastewater treatment technology, specifically to an intelligent dissolved air flotation (DAF) device and its pressure control system. The pressure control system includes: a data acquisition module for real-time acquisition of pressure data within the dissolved air tank of the intelligent DAF device, the amount of dissolved air in the polluted water within the tank, and the flow rate at the tank's inlet; a data analysis module for obtaining the turbulence characteristics and correlation asynchrony within the dissolved air tank at each acquisition time; further determining the fusion result of the flow rate at each acquisition time within a preset time period and all previous acquisition times; and obtaining the difference coefficient within the dissolved air tank at each acquisition time by assessing the difference in the trend between the fusion result and the dissolved air volume within the preset time period; and a pressure adjustment module for obtaining the correction pressure adjustment amount of the dissolved air tank at each acquisition time and regulating the pressure within the tank. This application aims to improve the accuracy of pressure control within the dissolved air tank.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment technology, specifically to an intelligent dissolved air flotation device and pressure control system. Background Technology

[0002] Dissolved air flotation (DAF) devices are used for wastewater treatment and reuse. They work by adding gas to water to create saturated water, which is then used to form microbubbles through a perforated plate. These bubbles adsorb suspended solids, grease, colloids, and other pollutants from the water. During saturation water formation, proper pressure control optimizes bubble characteristics, resulting in smaller bubbles and increased surface area for adsorbing more pollutants. This improves flotation efficiency, reduces energy consumption, and adapts to different wastewater treatment needs. Stable pressure also prevents clogging and extends the device's lifespan.

[0003] Existing technologies typically use PID (Proportional Integral Derivative) controllers to regulate the pressure inside the dissolved air flotation (DAF) tank. However, during operation, gas and water are continuously added to the tank to create supersaturated dissolved air solution. During this process, the agitator causes the liquid level inside the tank to fluctuate, leading to pressure changes. Traditional technologies do not distinguish whether the pressure changes are caused by changes in the air intake or by fluctuations in the liquid level. This results in poor pressure control when the PID controller directly regulates the pressure by collecting data, ultimately affecting the wastewater treatment and reuse efficiency of the DAF system. Summary of the Invention

[0004] In view of the above, it is necessary to provide an intelligent dissolved air flotation device and pressure control system, which improves the accuracy of pressure control within the dissolved air tank compared to traditional intelligent dissolved air flotation devices and pressure control systems.

[0005] In a first aspect, embodiments of this application provide a pressure control system for an intelligent dissolved air flotation device, the pressure control system comprising:

[0006] The data acquisition module is used to collect in real time the pressure data inside the dissolved air tank of the intelligent dissolved air flotation device, the amount of dissolved air in the polluted water inside the dissolved air tank, and the flow rate at the air inlet of the dissolved air tank.

[0007] The data analysis module is used to obtain the maximum dissolved gas volume under preset conditions in the dissolved gas tank, calculate the deviation between the maximum dissolved gas volume and the dissolved gas volume collected in real time, and obtain the turbulence characteristic degree in the dissolved gas tank at each collection time by the trend change degree and distribution symmetry degree of the deviation within a preset period before each collection time.

[0008] By comparing the dispersion of pressure data and dissolved gas volume within the preset time period, and comparing the synchronization degree between the deviation and the trend of pressure data change within the preset time period, the correlation and asynchrony degree within the dissolved gas tank at each collection time can be obtained.

[0009] The fusion result of the flow rate at each collection moment within the preset time period and all previous collection moments is determined. By combining the degree of difference between the fusion result and the change trend of dissolved gas volume within the preset time period with the turbulence characteristic degree and the correlation asynchrony degree, the difference coefficient in the dissolved gas tank at each collection moment is obtained.

[0010] The pressure regulation module is used to obtain the correction pressure adjustment amount of the dissolved gas tank at each sampling time through the difference coefficient and the difference between the pressure data at each sampling time and the preset pressure, and to regulate the pressure in the dissolved gas tank in conjunction with the PID controller.

[0011] In one embodiment, the process of obtaining the turbulence characteristic degree is as follows:

[0012] The data deviation at each acquisition time is obtained by assessing the symmetry of the distribution of all deviations within the preset time period.

[0013] Obtain the absolute value of the slope of the fitted straight line of all the deviations in the time series within the preset time period;

[0014] The turbulence characteristic degree is the product of the absolute value and the data deviation degree.

[0015] In one embodiment, the process of obtaining the data deviation is as follows:

[0016] Calculate the mean of all deviations within the preset time period, and count the maximum and minimum values ​​among all deviations within the preset time period; record the differences between the maximum value, the minimum value and the mean as the first difference value and the second difference value, respectively.

[0017] The data deviation is the amount of difference between the first difference value and the second difference value.

[0018] In one embodiment, the process of obtaining the associated asynchronicity is as follows:

[0019] All pressure data and all deviations within the preset time period are arranged in chronological order to form a pressure sequence and a dissolved gas quantity difference sequence; the first-order difference sequence of each pressure sequence and the first-order difference sequence of each dissolved gas quantity difference sequence are obtained respectively; positive values ​​in each first-order difference sequence are assigned the value 1, and negative values ​​are assigned the value -1.

[0020] Calculate the deviation between the dispersion of all pressure data and the dispersion of all dissolved gas quantities within the preset time period;

[0021] Calculate the sum of the deviations between all elements at the same position in the first-order difference sequence of the pressure sequence and the first-order difference sequence of the dissolved gas quantity at each acquisition time.

[0022] The degree of correlation asynchrony can be further obtained by the deviation value and the sum value.

[0023] In one embodiment, the degree of asynchrony is the product of the deviation value and the sum value.

[0024] In one embodiment, the process of obtaining the difference coefficient is as follows:

[0025] Calculate the cumulative value of the flow rate at each sampling moment within the preset time period and all previous sampling moments. Record the slopes of the fitted straight lines of all the cumulative values ​​and all dissolved gas volumes within the preset time period as the first slope and the second slope, respectively. Calculate the degree of difference between the first slope and the second slope.

[0026] Calculate the product of the turbulence characteristic degree and the associated asynchrony degree;

[0027] The difference coefficient is directly proportional to the difference degree and inversely proportional to the product value.

[0028] In one embodiment, the calculation process of the difference coefficient is as follows: mapping the product value to a positive number; the difference coefficient is the ratio of the difference degree to the positive number.

[0029] In one embodiment, the expression for the correction pressure adjustment amount is:

[0030] e j ′ =norm(DF j )×e j In the formula, e j ′ This represents the adjustment amount of the dissolved gas tank's correction pressure at the j-th acquisition time; norm() represents the normalization function; DF j e represents the difference coefficient within the dissolved gas tank at the j-th sampling time; j This represents the difference between the preset pressure and the pressure data at the j-th acquisition time.

[0031] In one embodiment, the process of regulating the pressure inside the dissolved gas tank is as follows:

[0032] The calibration pressure adjustment is used as the input of the PID controller, and the output control signal is used to control the opening of the gas inlet of the dissolved gas tank at each acquisition time, so as to regulate the pressure inside the dissolved gas tank.

[0033] Secondly, this application also provides an intelligent dissolved air flotation device, which includes a dissolved air tank and a control system.

[0034] The dissolved air tank is equipped with a pressure regulating device, which is used to receive the control signal output by the PID controller and adjust the opening of the air inlet of the dissolved air tank according to the control signal.

[0035] The control system is used to adjust and monitor the operating parameters of the entire intelligent dissolved air flotation device. The control system includes a pressure regulation system, which comprises:

[0036] The data acquisition module is used to collect in real time the pressure data inside the dissolved air tank of the intelligent dissolved air flotation device, the amount of dissolved air in the polluted water inside the dissolved air tank, and the flow rate at the air inlet of the dissolved air tank.

[0037] The data analysis module is used to obtain the maximum dissolved gas volume under preset conditions in the dissolved gas tank, calculate the deviation between the maximum dissolved gas volume and the dissolved gas volume collected in real time, and obtain the turbulence characteristic degree in the dissolved gas tank at each collection time by the trend change degree and distribution symmetry degree of the deviation within a preset period before each collection time.

[0038] By comparing the dispersion of pressure data and dissolved gas volume within the preset time period, and comparing the synchronization degree between the deviation and the trend of pressure data change within the preset time period, the correlation and asynchrony degree within the dissolved gas tank at each collection time can be obtained.

[0039] The fusion result of the flow rate at each collection moment within the preset time period and all previous collection moments is determined. By combining the degree of difference between the fusion result and the change trend of dissolved gas volume within the preset time period with the turbulence characteristic degree and the correlation asynchrony degree, the difference coefficient in the dissolved gas tank at each collection moment is obtained.

[0040] The pressure regulation module is used to obtain the correction pressure adjustment amount of the dissolved gas tank at each sampling time through the difference coefficient and the difference between the pressure data at each sampling time and the preset pressure, and input it into the PID controller. The PID controller outputs a control signal to control the opening degree of the air inlet of the dissolved gas tank at each sampling time, so as to regulate the pressure inside the dissolved gas tank.

[0041] This application has at least the following beneficial effects:

[0042] This application, by calculating the deviation between the maximum dissolved gas volume and the real-time dissolved gas volume, can intuitively reflect the dissolved gas state within the dissolved gas tank. By analyzing the trend changes and symmetry of the distribution of the deviation between the maximum and real-time dissolved gas volumes, the turbulence characteristic degree can be obtained, quantifying the degree of turbulence in the dissolved gas volume within the tank and providing a reference for pressure control. By calculating the correlation asynchrony, it can assess whether the pressure change is caused by the inlet gas volume or by liquid level fluctuations, helping to improve the accuracy of pressure control. Furthermore, by comprehensively considering the difference in the changing trends of the cumulative flow rate and the dissolved gas volume, as well as the turbulence characteristic degree and the correlation asynchrony, a difference coefficient can be obtained, enabling a comprehensive assessment of the impact of gas flow within the dissolved gas tank and providing a more accurate adjustment basis for pressure control.

[0043] Furthermore, by adjusting the difference between the preset pressure and the real-time pressure data through the difference coefficient, the pressure change requirements in the dissolved air flotation tank are accurately reflected. Combined with the PID controller, the pressure in the dissolved air flotation tank is dynamically and precisely controlled to ensure the stability of the pressure in the dissolved air flotation tank. This optimizes the formation of dissolved air water and the characteristics of bubbles, improves the flotation efficiency, reduces energy consumption, and enables the dissolved air flotation device to operate smoothly, thereby improving the effect of wastewater treatment and its reuse. Attached Figure Description

[0044] To more clearly illustrate the technical solutions and advantages in the embodiments of this application 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 this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 A schematic diagram of an intelligent dissolved air flotation device provided in one embodiment of this application;

[0046] Figure 2 A block diagram of a pressure control system for an intelligent dissolved air flotation device provided in one embodiment of this application;

[0047] Figure 3 This is a schematic diagram illustrating the process of obtaining the difference coefficient.

[0048] Figure 4 This is a schematic diagram illustrating the implementation process of the pressure control system in an intelligent dissolved air flotation device. Detailed Implementation

[0049] In the description of the embodiments in this application, the words "exemplary," "or," and "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design scheme described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design schemes. Specifically, the use of the words "exemplary," "or," and "for example" is intended to present the relevant concepts in a specific manner.

[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 application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. It should be understood that, unless otherwise stated, " / " in this application means "or".

[0051] It should also be noted that the terms "first" and "second" in this application are used to distinguish similar objects, rather than to describe a specific order or sequence.

[0052] The following description, in conjunction with the accompanying drawings, details the specific scheme of the intelligent dissolved air flotation device and pressure control system provided in this application.

[0053] Please see Figure 1 The illustration shows a schematic diagram of an intelligent dissolved air flotation device provided in one embodiment of this application. The intelligent dissolved air flotation device mainly includes: a dissolved air tank, a release system, a flotation tank, a circulation pump and a return pump, and a control system.

[0054] Inside the dissolved air tank, water is mixed with air or other gases under high pressure to form supersaturated dissolved air water. The dissolved air tank is equipped with a stirrer and a pressure regulating device to ensure that the gas is uniformly dissolved in the water. The pressure regulating device receives the control signal output from the PID controller and adjusts the opening of the air inlet of the dissolved air tank according to the control signal to control the gas flow rate entering the dissolved air tank, thereby maintaining the pressure stability inside the dissolved air tank.

[0055] Dissolved air water enters the flotation tank through a release system, which includes an orifice plate to reduce the pressure of the dissolved air water and cause the dissolved gas to form tiny bubbles.

[0056] A flotation tank is a place where water and air bubbles come into contact. The flotation tank is equipped with a sludge scraper to collect the floating pollutants and discharge them.

[0057] The circulating pump is used to circulate the water in the flotation tank to the dissolved air tank to improve the treatment efficiency; the return pump returns part of the treated water to the dissolved air tank to form dissolved air water.

[0058] The control system is used to adjust and monitor the operating parameters of the entire intelligent dissolved air flotation device, including pressure, flow rate, and dissolved air volume parameters, to ensure the efficient operation of wastewater treatment and its reuse. The control system includes a pressure regulation system, which consists of a data acquisition module, a data analysis module, and a pressure regulation module.

[0059] Among them, the data acquisition module is used to collect in real time the pressure data in the dissolved air tank of the intelligent dissolved air flotation device, the amount of dissolved air in the polluted water in the dissolved air tank, and the flow rate of the air inlet of the dissolved air tank.

[0060] The data analysis module is used to obtain the maximum dissolved gas volume under preset conditions in the dissolved gas tank, calculate the deviation between the maximum dissolved gas volume and the dissolved gas volume collected in real time, and obtain the turbulence characteristic degree in the dissolved gas tank at each collection time by the trend change degree and distribution symmetry degree of the deviation within a preset period before each collection time.

[0061] By comparing the dispersion of pressure data and dissolved gas volume within the preset time period, and comparing the synchronization degree between the deviation and the trend of pressure data change within the preset time period, the correlation and asynchrony degree within the dissolved gas tank at each collection time can be obtained.

[0062] The fusion result of the flow rate at each collection moment within the preset time period and all previous collection moments is determined. By combining the degree of difference between the fusion result and the change trend of dissolved gas volume within the preset time period with the turbulence characteristic degree and the correlation asynchrony degree, the difference coefficient in the dissolved gas tank at each collection moment is obtained.

[0063] The pressure regulation module is used to obtain the correction pressure adjustment amount of the dissolved gas tank at each sampling time through the difference coefficient and the difference between the pressure data at each sampling time and the preset pressure, and input it into the PID controller. The PID controller outputs a control signal to control the opening degree of the air inlet of the dissolved gas tank at each sampling time, so as to regulate the pressure inside the dissolved gas tank.

[0064] Please see Figure 2 The diagram shows a block diagram of a pressure control system for an intelligent dissolved air flotation device according to an embodiment of this application. The pressure control system includes: a data acquisition module 101, a data analysis module 102, and a pressure regulation module 103.

[0065] The data acquisition module 101 is used to collect in real time the pressure data inside the dissolved air tank of the intelligent dissolved air flotation device, the amount of dissolved air in the polluted water inside the dissolved air tank, and the flow rate at the air inlet of the dissolved air tank.

[0066] In the process of wastewater treatment and reuse, it is necessary to monitor the pressure data inside the dissolved air tank, the dissolved air volume in the polluted water inside the tank, and the flow rate at the tank's inlet. Therefore, pressure sensors, flow sensors, and dissolved air pressure sensors installed inside the tank are used to collect real-time data on the pressure inside the tank, the flow rate at the tank's inlet, and the dissolved air volume in the polluted water. The dissolved air volume specifically refers to the concentration of dissolved air. Because the objects collected by the pressure sensors, flow sensors, and dissolved air pressure sensors are highly mobile, the collected pressure data, flow rate, and dissolved air volume may contain missing data and noise. Therefore, the collected pressure data, flow rate, and dissolved air volume need to be processed for missing data filling and noise reduction.

[0067] In this embodiment, the sampling frequency of the pressure sensor, flow sensor and dissolved gas pressure sensor is 10Hz. The sampling frequency value is preset by the user and can be set by the implementer according to the actual situation. This application does not impose any special restrictions.

[0068] In this embodiment, linear interpolation is used to fill in the missing data. Linear interpolation is a well-known technique and will not be described in detail here. As other implementation methods, based on the ability to fill in the missing data, implementers may use other existing techniques, such as mean filling methods, etc. This application does not impose any special restrictions.

[0069] In this embodiment, a Savitzky-Golay filter is used to denoise the collected pressure data, flow rate, and dissolved gas volume respectively. The Savitzky-Golay filter is a well-known technology and will not be described in detail in this application. As other implementation methods, based on the ability to denoise the collected pressure data, flow rate, and dissolved gas volume respectively, the implementer may use other existing technologies, such as mean filtering methods, etc. This application does not impose any special restrictions.

[0070] The data analysis module 102 is used to analyze the pressure data, dissolved gas volume and flow rate collected in real time, and to obtain the difference coefficient in the dissolved gas tank at each collection time.

[0071] In the process of wastewater treatment and reuse, dissolved air water is generated by adding gas to water in a dissolved air tank. Under stable pressure and temperature, the maximum volume of gas that dissolves in water is fixed. Therefore, when the water in the dissolved air tank reaches supersaturation, the gas added through the inlet will no longer dissolve in the water; it will only increase the volume of gas above the liquid surface in the tank, increasing the pressure inside. To ensure the safe and stable operation of the dissolved air tank, it is necessary to maintain stable gas pressure. Therefore, it is necessary to reduce the gas intake to maintain pressure balance and improve the efficiency of wastewater treatment and reuse.

[0072] (1) Obtain the maximum dissolved gas volume under preset conditions in the dissolved gas tank, calculate the deviation between the maximum dissolved gas volume and the dissolved gas volume collected in real time, and obtain the turbulence characteristic degree in the dissolved gas tank at each collection time by the trend change degree and distribution symmetry degree of the deviation in the preset period before each collection time.

[0073] Based on the above analysis, Henry's Law is used to obtain the maximum dissolved gas volume under preset conditions within the dissolved gas tank. The difference between the maximum dissolved gas volume and the dissolved gas volume collected in real time is recorded as the dissolved gas deficit. All dissolved gas deficits within the preset time period before each collection time are arranged chronologically to form a sequence of dissolved gas volume differences at each collection time. When all data in the dissolved gas volume difference sequence lie on a horizontal straight line, it indicates that the difference between the maximum dissolved gas volume and the actual amount of gas dissolved in the dissolved gas tank is constant. Therefore, the actual amount of gas dissolved in the dissolved gas tank is stable. Fluctuations in the liquid level within the dissolved gas tank will affect the local dissolution efficiency. Since the actual amount of gas dissolved in the dissolved gas tank is stable, the liquid level does not change frequently. Therefore, fluctuations in the gas pressure within the dissolved gas tank are not caused by fluctuations in the liquid level during agitation by the stirrer within the dissolved gas tank. In the above case, the center of the pressure data fluctuation is the true pressure within the dissolved gas tank.

[0074] In this embodiment, the preset time period before each collection time is specifically the 1 minute preceding each collection time. The length of the preset time period is preset by the user and can be set by the implementer according to the actual situation. This application does not impose any special restrictions.

[0075] In this embodiment, the preset conditions in the dissolved gas tank are 0.3 MPa and 25°C water temperature. Therefore, the maximum dissolved gas volume in the dissolved gas tank calculated using Henry's Law is 2.25 L.

[0076] Furthermore, the data deviation at each collection time is obtained by assessing the symmetry of the distribution of dissolved gas deficiency in the dissolved gas quantity difference sequence at each collection time. The expression is as follows:

[0077] In the formula, kf j Q represents the data deviation at the j-th acquisition time; j,max Q j,min These represent the maximum and minimum values ​​of dissolved gas missing amounts among all dissolved gas missing amounts in the dissolved gas difference sequence at the j-th acquisition time, respectively. This represents the mean of all dissolved gas missing values ​​in the dissolved gas difference sequence at the j-th acquisition time; |*| indicates the absolute value operation. These are denoted as the first difference value and the second difference value, respectively.

[0078] It should be noted that the smaller the data deviation, the higher the symmetry of the distribution of dissolved gas missing amount in the dissolved gas amount difference sequence, and the higher the stability of the dissolved gas amount in the polluted water in the dissolved gas tank.

[0079] Furthermore, by analyzing the trend of dissolved gas loss in the dissolved gas volume difference sequence at each sampling time, and the data deviation at each sampling time, the turbulence characteristic of the dissolved gas tank at each sampling time is obtained, expressed as:

[0080] TFG j =|K j |×kf j In the formula, TFG j K represents the turbulence characteristic degree inside the dissolved gas tank at the j-th acquisition time; j The slope of the fitted straight line representing the dissolved gas quantity difference sequence at the j-th acquisition time; |*| represents the absolute value operation; kf j This represents the data deviation at the j-th acquisition time. The calculation of the slope is a well-known technique and will not be elaborated upon in this application.

[0081] In this embodiment, the least squares method is used to obtain the fitted straight line of the dissolved gas difference sequence. The least squares method is a well-known technique and will not be described in detail in this application. As other implementation methods, based on the ability to obtain the fitted straight line of the dissolved gas difference sequence, the implementer may use other existing techniques, such as linear regression analysis, weighted least squares method, etc. This application does not impose any special restrictions.

[0082] It should be noted that: for dissolved air water in a dissolved air tank, if the dissolved air volume remains stable, it means that the amount of gas absorbed is fixed, and the smaller the absolute value of the slope of the fitted straight line of the dissolved air volume difference sequence; at the same time, the smaller the data deviation, the higher the stability of the dissolved air volume in the polluted water in the dissolved air tank; at this time, the higher the dissolved air volume in the polluted water in the dissolved air tank, the more microbubbles can be generated, more water pollutants can be adsorbed, the better the effect of sewage treatment and its reuse, and the faster the water purification efficiency.

[0083] (2) By comparing the dispersion of pressure data and the dispersion of dissolved gas within the preset time period, and by comparing the synchronization degree of the deviation and the trend of pressure data change within the preset time period, the correlation and asynchrony degree of dissolved gas tank at each collection time is obtained.

[0084] Because the dissolving of gas in the dissolved air tank is a continuous process, the saturated dissolved air water in the tank enters the flotation tank through the outlet, while water needs to be continuously added to the dissolved air tank through the inlet. This necessitates a continuous supply of gas into the dissolved air tank, causing pressure changes within the tank. When the dissolved air water can no longer absorb gas, the pressure inside the dissolved air tank will continuously rise even without releasing gas.

[0085] When the dissolved gas volume and pressure within the dissolved gas tank maintain a similar rate of change, it indicates that the pressure within the tank is primarily affected by the inlet gas flow rate, rather than by pressure changes caused by fluctuations in the liquid level. All pressure data from the preset time period preceding each acquisition time are arranged chronologically to form a pressure sequence for each acquisition time. The first-order difference sequence of each pressure sequence and the first-order difference sequence of each dissolved gas volume difference sequence are then obtained. Positive values ​​in each first-order difference sequence are assigned a value of 1, and negative values ​​are assigned a value of -1, to characterize the direction of pressure data variation and the direction of dissolved gas loss variation between adjacent acquisition times. All dissolved gas volumes from the preset time period preceding each acquisition time are arranged chronologically to form a dissolved gas volume sequence for each acquisition time.

[0086] Furthermore, by comparing the dispersion of pressure data in the pressure sequence and the dispersion of dissolved gas volume in the dissolved gas volume sequence at each acquisition time, and by comparing the first-order difference sequence of the pressure sequence and the first-order difference sequence of the dissolved gas volume difference sequence at each acquisition time, the correlation asynchrony degree within the dissolved gas tank at each acquisition time is obtained, expressed as:

[0087] In the formula, Rgf j This indicates the degree of correlation asynchrony within the dissolved gas tank at the j-th acquisition time; |*| represents the absolute value operation; BH j BE represents the dispersion of pressure data in the pressure sequence at the j-th acquisition time. j UH represents the dispersion of dissolved gas quantity in the dissolved gas quantity sequence at the j-th acquisition time; N represents the length of the first-order difference sequence; UH j,i EF represents the i-th element in the first-order difference sequence of the pressure sequence at the j-th acquisition time; j,i Let i represent the i-th element in the first-order difference sequence of the dissolved gas quantity difference sequence at the j-th sampling time.

[0088] In this embodiment, the dispersion involved in the calculation of the correlation asynchrony degree is the coefficient of variation. The coefficient of variation is a well-known technology and will not be described in detail in this application. As other implementation methods, based on the ability to measure the uneven distribution of pressure data and the uneven distribution of dissolved gas, the implementer may use other existing technologies, such as standard deviation and variance. This application does not impose any special restrictions.

[0089] It should be noted that for the gas entering the dissolved gas tank, a portion will dissolve in the water, and a portion will be released from the top of the tank to maintain pressure balance. Therefore, when the opening of the release valve remains constant, the pressure inside the dissolved gas tank will increase as the amount of dissolved gas decreases. This results in a high degree of synchronicity between the pressure sequence and the dissolved gas quantity difference sequence, leading to a smaller difference in the first-order difference sequences between them. Furthermore, the smaller the difference in dispersion between the pressure sequence and the dissolved gas quantity sequence during the dissolution process, the stronger the correlation between the pressure and the dissolved gas quantity within the tank, resulting in a smaller degree of asynchrony within the dissolved gas tank and more accurate pressure data detected at the j-th acquisition time.

[0090] (3) Determine the fusion result of the flow rate at each collection time within the preset time period and all previous collection times. By combining the degree of difference between the fusion result and the change trend of dissolved gas volume within the preset time period with the turbulence characteristic degree and the correlation asynchrony degree, obtain the difference coefficient in the dissolved gas tank at each collection time.

[0091] Furthermore, regarding the intake rate of the dissolved air tank, the greater the change in the intake rate while the dissolved amount in the tank remains constant, the greater the pressure change inside the tank. Therefore, when controlling the pressure inside the dissolved air tank, it is necessary to enhance the pressure control capability to ensure the pressure balance inside the tank, so as to better treat water pollution and improve the effectiveness and quality of wastewater treatment and its reuse.

[0092] The cumulative value of the flow rate at each sampling moment within the preset time period and all previous sampling moments is calculated. All the cumulative values ​​within the preset time period preceding each sampling moment are arranged chronologically to form a cumulative sequence for each sampling moment. The slopes of the fitted lines for the cumulative sequences and the fitted lines for the dissolved gas volume sequences at each sampling moment are obtained respectively, to characterize the changes in the cumulative gas intake and dissolved gas volume in the dissolved gas tank. The calculation of the slopes is a known technique and will not be elaborated upon in this application.

[0093] In this embodiment, the least squares method is used to obtain the fitted straight line of the cumulative sequence and the fitted straight line of the dissolved gas quantity sequence, respectively. The least squares method is a well-known technique and will not be described in detail in this application. As other implementation methods, based on the ability to obtain the fitted straight line of the cumulative sequence and the fitted straight line of the dissolved gas quantity sequence, the implementer may use other existing techniques, such as linear regression analysis, weighted least squares method, etc. This application does not impose any special restrictions.

[0094] Furthermore, by analyzing the differences in data trends between the accumulated sequence and the dissolved gas volume sequence at each acquisition time, and combining the turbulence characteristics within the dissolved gas tank at each acquisition time with the aforementioned correlation asynchrony, the difference coefficient within the dissolved gas tank at each acquisition time is obtained, expressed as:

[0095] In the formula, DF j k represents the difference coefficient within the dissolved gas tank at the j-th sampling time; j,1 k j,2 Let represent the slopes of the fitted lines for the accumulated sequence and dissolved gas volume sequence at the j-th acquisition time, respectively; |*| represents the absolute value operation; TFG j Rgf represents the turbulence characteristic degree within the dissolved gas tank at the j-th acquisition time. j ε represents the degree of correlation asynchrony within the dissolved gas tank at the j-th acquisition time; ε represents a preset positive number used to avoid a denominator of 0. The value of ε is preset manually and can be set by the implementer. In this embodiment, the value of ε is 0.01. Let k j,1 k j,2 These are denoted as the first slope and the second slope, respectively.

[0096] It should be noted that when the pressure inside the dissolved air flotation (DAF) tank is caused by the total amount of air intake, and the water body cannot dissolve more gas, the difference between the slope of the cumulative sequence fitting line and the slope of the tank dissolved air flotation sequence fitting line will increase. Simultaneously, the turbulence characteristic and correlation asynchrony within the DAF tank will decrease. This indicates that the collected pressure data is affected by the air intake volume, rather than by the liquid fluctuations within the DAF tank. In this case, the difference between the pressure data and the preset pressure is the required pressure adjustment. Accurate pressure adjustment can improve the efficiency of the DAF flotation device for wastewater treatment and reuse. A schematic diagram of the difference coefficient acquisition process is shown below. Figure 3 As shown.

[0097] The pressure regulation module 103 is used to obtain the correction pressure adjustment amount of the dissolved gas tank at each sampling time through the difference coefficient and the difference between the pressure data at each sampling time and the preset pressure, and to regulate the pressure in the dissolved gas tank in conjunction with the PID controller.

[0098] The difference between the preset pressure and the pressure data at each acquisition time is recorded as the initial pressure adjustment. A larger difference coefficient within the dissolved gas tank indicates that the pressure change is more likely caused by the amount of gas entering the tank; conversely, a smaller coefficient suggests that the pressure change is more likely due to liquid level fluctuations caused by the agitator. Furthermore, the agitator's movement within the dissolved gas tank causes liquid level fluctuations, which in turn cause pressure data fluctuations even in a dissolved gas equilibrium state (where the amount of gas entering the tank equals the amount dissolved in the water). Therefore, when adjusting the pressure within the dissolved gas tank, it is only necessary to reduce the initial pressure adjustment; that is, to correct the initial pressure adjustment so that the corrected pressure adjustment is less than the initial pressure adjustment.

[0099] Based on the above analysis, the initial pressure adjustment at each sampling time is corrected using the difference coefficient within the dissolved gas tank at each sampling time, resulting in the corrected pressure adjustment amount for the dissolved gas tank at each sampling time, expressed as:

[0100] e j ′ =norm(DF j )×e j In the formula, e j ′ This represents the adjustment amount of the dissolved gas tank's correction pressure at the j-th acquisition time; norm() represents the normalization function; DF j e represents the difference coefficient within the dissolved gas tank at the j-th sampling time; j This represents the difference between the preset pressure and the pressure data at the j-th acquisition time, i.e., the initial pressure adjustment amount at the j-th acquisition time.

[0101] In this embodiment, the normalization function is specifically the sigmoid function. The sigmoid function is a well-known technique and will not be described in detail here.

[0102] The calculated correction pressure adjustment of the dissolved air flotation (DAF) tank at each data acquisition time is used as the input to the PID controller, which outputs a control signal. This control signal controls the opening of the DAF tank's inlet to regulate the pressure within the tank, thereby improving the efficiency of the DAF device in wastewater treatment and reuse, and realizing the concept of green and environmentally friendly development. A schematic diagram of the pressure regulation system implementation of the intelligent DAF device is shown below. Figure 4 As shown.

[0103] In summary, this application, by calculating the deviation between the maximum dissolved gas volume and the real-time dissolved gas volume, can intuitively reflect the dissolved gas state within the dissolved gas tank. By analyzing the trend changes and symmetry of the distribution of the deviation between the maximum and real-time dissolved gas volumes, the turbulence characteristic degree can be obtained, quantifying the degree of turbulence in the dissolved gas volume changes within the tank and providing a reference for pressure control. By calculating the correlation asynchrony, it can assess whether the pressure change is caused by the inlet gas volume or by liquid level fluctuations, which helps improve the accuracy of pressure control. Furthermore, by comprehensively considering the difference in the trends of cumulative flow and dissolved gas volume changes, as well as the turbulence characteristic degree and the correlation asynchrony, a difference coefficient can be obtained, enabling a comprehensive assessment of the impact of gas flow within the dissolved gas tank and providing a more accurate adjustment basis for pressure control.

[0104] Furthermore, by adjusting the difference between the preset pressure and the real-time pressure data through the difference coefficient, the pressure change requirements in the dissolved air flotation tank are accurately reflected. Combined with the PID controller, the pressure in the dissolved air flotation tank is dynamically and precisely controlled to ensure the stability of the pressure in the dissolved air flotation tank. This optimizes the formation of dissolved air water and the characteristics of bubbles, improves the flotation efficiency, reduces energy consumption, and enables the dissolved air flotation device to operate smoothly, thereby improving the effect of wastewater treatment and its reuse.

[0105] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. In some alternative implementations, the functions marked in the blocks may occur in a different order than that shown in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. In the descriptions corresponding to the flowcharts and block diagrams in the accompanying drawings, the operations or steps corresponding to different blocks may also occur in a different order than disclosed in the description, and sometimes there is no specific order between different operations or steps. For example, two consecutive operations or steps may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. Each block in a block diagram and / or flowchart, and combinations of blocks in a block diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0106] It will be apparent to those skilled in the art that this application is not limited to the details of the exemplary embodiments described above, and that this application can be implemented in other specific forms without departing from its essential characteristics. Therefore, the embodiments described above should be considered exemplary and non-limiting in all respects.

Claims

1. A pressure control system for an intelligent dissolved air flotation device, characterized in that, The pressure control system includes: The data acquisition module is used to collect in real time the pressure data inside the dissolved air tank of the intelligent dissolved air flotation device, the amount of dissolved air in the polluted water inside the dissolved air tank, and the flow rate at the air inlet of the dissolved air tank. The data analysis module is used to obtain the maximum dissolved gas volume under preset conditions in the dissolved gas tank, calculate the deviation between the maximum dissolved gas volume and the dissolved gas volume collected in real time, and obtain the turbulence characteristic degree in the dissolved gas tank at each collection time by the trend change degree and distribution symmetry degree of the deviation within a preset period before each collection time. By comparing the dispersion of pressure data and dissolved gas volume within the preset time period, and comparing the synchronization degree between the deviation and the trend of pressure data change within the preset time period, the correlation and asynchrony degree within the dissolved gas tank at each collection time can be obtained. The fusion result of the flow rate at each collection moment within the preset time period and all previous collection moments is determined. By combining the degree of difference between the fusion result and the change trend of dissolved gas volume within the preset time period with the turbulence characteristic degree and the correlation asynchrony degree, the difference coefficient in the dissolved gas tank at each collection moment is obtained. The pressure regulation module is used to obtain the correction pressure adjustment amount of the dissolved gas tank at each sampling time through the difference coefficient and the difference between the pressure data at each sampling time and the preset pressure, and to regulate the pressure in the dissolved gas tank in conjunction with the PID controller. The process of obtaining the turbulence characteristic degree is as follows: The data deviation at each acquisition time is obtained by assessing the symmetry of the distribution of all deviations within the preset time period. Obtain the absolute value of the slope of the fitted straight line of all the deviations in the time series within the preset time period; The turbulence characteristic degree is the product of the absolute value and the data deviation degree; The expression for the data deviation is: ; This represents the data deviation at the j-th acquisition time. , These represent the maximum and minimum values ​​of dissolved gas missing amounts among all dissolved gas missing amounts in the dissolved gas difference sequence at the j-th acquisition time, respectively. The value represents the average of all dissolved gas missing amounts in the dissolved gas difference sequence at the j-th collection time. The difference between the maximum dissolved gas amount and the dissolved gas amount collected in real time is recorded as the dissolved gas missing amount. All dissolved gas missing amounts within a preset time period before each collection time are arranged in chronological order to form the dissolved gas difference sequence at each collection time. The process of obtaining the associated asynchronous degree is as follows: Arrange all pressure data within the preset time period in chronological order to form a pressure sequence; obtain the first-order difference sequence of each pressure sequence and the first-order difference sequence of each dissolved gas quantity difference sequence; assign 1 to positive values ​​and -1 to negative values ​​in each first-order difference sequence. Calculate the deviation between the dispersion of all pressure data and the dispersion of all dissolved gas quantities within the preset time period; the dispersion is the coefficient of variation. Calculate the sum of the deviations between all elements at the same position in the first-order difference sequence of the pressure sequence and the first-order difference sequence of the dissolved gas quantity at each acquisition time. The product of the sum and the deviation is taken as the degree of correlation asynchrony. The process of obtaining the difference coefficient is as follows: Calculate the cumulative value of the flow rate at each sampling moment within the preset time period and all previous sampling moments, and denote the slopes of the fitted straight lines of all the cumulative values ​​and all dissolved gas volumes within the preset time period as the first slope and the second slope, respectively. The expression for the coefficient of difference is: In the formula, This represents the difference coefficient within the dissolved gas tank at the j-th sampling time. , Let represent the first slope and the second slope at the j-th acquisition time, respectively; This represents the turbulence characteristic degree inside the dissolved gas tank at the j-th data acquisition time. This represents the degree of correlation asynchrony within the dissolved gas tank at the j-th acquisition time; ε represents a preset positive number. The expression for the correction pressure adjustment amount is: In the formula, This represents the adjustment amount of the dissolved gas tank's correction pressure at the j-th acquisition time; norm() represents the normalization function; This represents the difference coefficient within the dissolved gas tank at the j-th sampling time. This represents the difference between the preset pressure and the pressure data at the j-th acquisition time.

2. The pressure control system of the intelligent dissolved air flotation device as described in claim 1, characterized in that, The process of regulating the pressure inside the dissolved gas tank is as follows: The calibration pressure adjustment is used as the input of the PID controller, and the output control signal is used to control the opening of the gas inlet of the dissolved gas tank at each acquisition time, so as to regulate the pressure inside the dissolved gas tank.

3. An intelligent dissolved air flotation device, employing the pressure control system of the intelligent dissolved air flotation device as described in claim 1, characterized in that, The intelligent dissolved air flotation device includes: a dissolved air tank and a control system; The dissolved air tank is equipped with a pressure regulating device, which is used to receive the control signal output by the PID controller and adjust the opening of the air inlet of the dissolved air tank according to the control signal. The control system is used to adjust and monitor the operating parameters of the entire intelligent dissolved air flotation device. The control system includes a pressure regulation system, which comprises: The data acquisition module is used to collect in real time the pressure data inside the dissolved air tank of the intelligent dissolved air flotation device, the amount of dissolved air in the polluted water inside the dissolved air tank, and the flow rate at the air inlet of the dissolved air tank. The data analysis module is used to obtain the maximum dissolved gas volume under preset conditions in the dissolved gas tank, calculate the deviation between the maximum dissolved gas volume and the dissolved gas volume collected in real time, and obtain the turbulence characteristic degree in the dissolved gas tank at each collection time by the trend change degree and distribution symmetry degree of the deviation within a preset period before each collection time. By comparing the dispersion of pressure data and dissolved gas volume within the preset time period, and comparing the synchronization degree between the deviation and the trend of pressure data change within the preset time period, the correlation and asynchrony degree within the dissolved gas tank at each collection time can be obtained. The fusion result of the flow rate at each collection moment within the preset time period and all previous collection moments is determined. By combining the degree of difference between the fusion result and the change trend of dissolved gas volume within the preset time period with the turbulence characteristic degree and the correlation asynchrony degree, the difference coefficient in the dissolved gas tank at each collection moment is obtained. The pressure regulation module is used to obtain the correction pressure adjustment amount of the dissolved gas tank at each sampling time through the difference coefficient and the difference between the pressure data at each sampling time and the preset pressure, and input it into the PID controller. The PID controller outputs a control signal to control the opening degree of the air inlet of the dissolved gas tank at each sampling time, so as to regulate the pressure inside the dissolved gas tank.

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