Method for measuring oxygen transfer performance of aerator based on oxygen transfer efficiency detector

Abstract

The application discloses a kind of aerator clean water oxygen transfer performance determination methods based on oxygen transfer efficiency detector, including preparation process and test process: preparation process: set to be measured aerator, check whether system is air leakage, and confirm whether the air supply capacity of air blower meets the test demand, confirm test condition;Test process: add catalyst, measure clean water dissolved oxygen concentration, add excess anhydrous Na2SO3, open air blower, wait for clean water to be completely oxygen depleted, slowly increase air blower frequency, confirm the preset value of aerator ventilation AFR, with oxygen transfer efficiency detector in sequence determination each AFR set value corresponding oxygen transfer efficiency OTE, and record test data;After testing, draw aerator OTE-AFR curve, confirm the clean water oxygen transfer performance of aerator under different ventilation conditions.The application can greatly reduce the labor cost of aerator clean water oxygen transfer performance test work, reduce air blower power consumption, and improve the accuracy of test results.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sewage treatment, in particular to a method for measuring the oxygen transfer performance of an aerator based on an oxygen transfer efficiency detector. BACKGROUND

[0002] In the field of contemporary sewage treatment, microporous aerators are a common gas mass transfer device that injects gas into water through small pores to achieve an efficient gas mass transfer process. The oxygen transfer performance test of microporous aerators is carried out in clean water. The existing method includes three steps: (1) water injection of the test device; (2) oxygen removal by adding chemicals, and after complete oxygen removal, constant aeration is carried out in clean water until the dissolved oxygen concentration DO reaches saturation, completing the first aeration. Then, oxygen removal is carried out again by adding chemicals, and after complete oxygen removal, constant aeration is carried out in clean water at the same constant aeration rate until the dissolved oxygen concentration DO reaches saturation, completing the second aeration; (3) water discharge of the test device. After the test is completed, the oxygen transfer performance of the aerator in clean water is calculated from the DO rising curve.

[0003] However, the existing method has some limitations and deficiencies. First, in the existing method, constant aeration is required until the DO reaches saturation, which is time-consuming, and the time for two "aerations until the DO reaches saturation", plus the time for "water injection of the test device" and "water discharge of the test device", will take about 1 to 3 working days (depending on the size of the test). And when measuring the oxygen transfer performance of the aerator in clean water under different aeration rates, multiple tests must be carried out at different aeration rates, which is extremely costly in terms of manpower. Second, the existing method cannot directly measure the oxygen transfer performance of the aerator in clean water, and complex data processing of the measured DO data must be carried out to obtain the results. In addition, when the dissolved oxygen probe is touched by bubbles or the aeration is uneven, the dissolved oxygen concentration data is inaccurate, resulting in errors in the test results.

[0004] Oxygen transfer efficiency OTE is a key parameter for measuring the oxygen transfer performance of an aerator, and its value can be directly output by an oxygen transfer efficiency detector. The oxygen transfer efficiency detector mainly measures the content of oxygen gas in the gas (tail gas) escaping from the surface of the aeration tank, and outputs the OTE value in combination with the content of the corresponding gas in the air.

[0005] The method can overcome the shortcomings of the prior art, on the one hand, the method can greatly shorten the test time and reduce the labor cost, and reduce the power consumption of the air blower, because the method does not need to wait for “DO to reach saturation” for several hours, but only needs to wait for the OTE reading of the oxygen transfer efficiency detector to be stable for 5 to 15 minutes (which varies with the air flow), and the method can further save the “water injection” and “water discharge” steps in the prior art, so that the test that originally takes 10 working days can be completed in 1 to 2 working days, thereby greatly shortening the test time and reducing the labor cost. On the other hand, the method can directly obtain the result without additional data processing, thereby further reducing the labor cost. In addition, the oxygen transfer efficiency of the aerator can be more accurately measured by completely collecting the tail gas of the aeration tank, the influence of the bubbles on the accuracy of the result caused by the contact between the dissolved oxygen detector probe and the bubbles is completely eliminated, and the influence of the uneven aeration on the accuracy of the result is greatly reduced. SUMMARY

[0006] The present application overcomes the shortcomings of the prior art, and provides an aeration device clean water oxygen transfer performance determination method based on an oxygen transfer efficiency detector to solve the problems in the background art.

[0007] An aeration device clean water oxygen transfer performance determination method based on an oxygen transfer efficiency detector, the determination method comprises a preparation process and a test process:

[0008] Step S1, preparation process: setting the aeration device to be tested, checking whether the system leaks, confirming whether the air supply capacity of the air blower meets the test requirements, and confirming the test conditions, wherein the test conditions include the test water depth H, the aeration device air flow AFR setting range [AFR min , AFR max ], the bottom area of the test device, and the number of aeration devices installed;

[0009] Step S2, test process: adding a catalyst, measuring the dissolved oxygen concentration of clean water, adding excess anhydrous Na2SO3, turning on the air blower, waiting for the clean water to be completely deoxygenated, slowly increasing the frequency of the air blower, confirming the preset value of the aeration device air flow AFR, and using the oxygen transfer efficiency detector to measure the oxygen transfer efficiency OTE corresponding to each AFR setting value in turn, and recording the test data;

[0010] Step S3, after the test is completed, an aeration device OTE-AFR curve is drawn, and the clean water oxygen transfer performance of the aeration device under different air flow conditions is confirmed.

[0011] As a further scheme of the present application, the specific step of adding excess anhydrous Na2SO3 includes:

[0012] The amount of anhydrous Na2SO3 added is calculated according to the volume V of clean water and the initial dissolved oxygen concentration DO0 of the clean water, and the calculation formula is as follows:

[0013]

[0014] Among them, is the amount of anhydrous Na2SO3 added, g; N is the number of set values of the AFR to be measured; DO0 is the initial dissolved oxygen concentration of the clean water, mg / L; K is the safety factor.

[0015] As a further scheme of the present application, the specific step of slowly increasing the frequency of the air blower includes:

[0016] Observing whether the offgas_F measured by the oxygen transfer efficiency detector reaches offgas_F min , and whether the AFR measured by the gas flow meter reaches AFR min .

[0017] If both indicators meet the conditions, the frequency of the air blower is fixed; otherwise, the frequency of the air blower is continuously slowly increased.

[0018] As a further scheme of the present application, the specific step of confirming the preset value of the aeration amount AFR includes:

[0019] Recording the aeration amount AFR after the current fixed frequency of the air blower as AFR1, as the minimum set value of AFR;

[0020] Setting AFR max as AFR5 as the maximum set value of AFR, then AFR2, AFR3, AFR4 are four equal points in the closed interval [AFR1, AFR5];

[0021] Among them, the preset value of the aeration amount AFR, then AFR1, AFR2, AFR3, AFR4, and AFR5 are five set values from small to large.

[0022] As a further scheme of the present application, the specific step of using the oxygen transfer efficiency detector to measure the oxygen transfer efficiency OTE corresponding to each AFR set value in turn includes starting from AFR1, using each AFR set value for testing from small to large, and entering a test cycle.

[0023] As a further scheme of the present application, the specific step of the test cycle includes:

[0024] Fixing the frequency of the air blower to the aeration amount AFR ncontinuously aerate;

[0025] When DO obviously rises, add anhydrous Na2SO3, and wait until the water is completely deoxygenated, and then start the cycle again;

[0026] When DO does not obviously rise, and the oxygen transfer efficiency OTE is still changing, continue to wait until the OTE is basically unchanged;

[0027] When DO does not obviously rise, and the oxygen transfer efficiency OTE is basically unchanged within 10 minutes, record the current OTE as OTE n , and record other test data, if there are still AFR set values that have not been tested, adjust the frequency of the air blower until the aeration amount AFR approaches AFR n+1 , enter the next cycle; otherwise, turn off the air blower, empty the water, and end the test.

[0028] As a further scheme of the present application: the aeration amount AFR n is continuously aerated, wherein AFR n is the nth AFR set value, and in 5 test cycles, the values are AFR1, AFR2, AFR3, AFR4, and AFR5 in turn;

[0029] When DO obviously rises, the determination step is:

[0030] DO-DO 消氧后 ≥0.2mg / L

[0031] Wherein, DO is the current DO value, mg / L; DO 消氧后 is the minimum DO value after the complete deoxygenation of the excess anhydrous Na2SO3, mg / L; when the above inequality is established, it is determined that DO obviously rises; otherwise, it is determined that DO does not obviously rise;

[0032] When DO obviously rises, add anhydrous Na2SO3, and the calculation formula of the amount of anhydrous Na2SO3 added is:

[0033]

[0034] Wherein, the oxygen transfer efficiency OTE is basically unchanged, and the determination step is:

[0035] OTE 过去10分钟内的最大值 -OTE 过去10分钟内的最小值 <0.1%

[0036] When the above inequality is established, it is determined that OTE is basically unchanged; otherwise, it cannot be determined that OTE is basically unchanged;

[0037] And adjust the frequency of the air blower until the aeration amount AFR approaches AFR n+1 , wherein AFRn+1 next AFR set value, ventilation amount close to AFR n+1 , the determination method is as follows:

[0038] |AFR-AFR n+1 |<1m 3 / h

[0039] Wherein, AFR is the ventilation amount after adjusting the frequency of the air blower, m 3 / h; AFR n+1 is the next AFR set value, m 3 / h; when the above inequality is established, it is determined that the ventilation amount AFR is close to AFR n+1 ; otherwise, it is determined that the ventilation amount AFR is not close to AFR n+1 .

[0040] As a further scheme of the present application: the specific step after the test is ended is to draw an aerator OTE-AFR curve, including drawing a scatter plot with 5 groups (AFR n , OTE n ) data as the ordinate and AFR as the abscissa, and fitting a power function as:

[0041]

[0042] Wherein, p1 and p2 are parameters of the fitting function.

[0043] Compared with the prior art, the present application has the following technical effects:

[0044] By adopting the above technical scheme, the test method gradually adjusts the ventilation amount of the aerator in a single test, and directly measures the OTE of the aerator under different ventilation conditions using an oxygen transfer efficiency detector, so as to finally obtain the OTE-AFR curve of the aerator, so as to confirm the oxygen transfer performance of the aerator under different ventilation conditions. When measuring the oxygen transfer performance of the aerator under different ventilation conditions, compared with the traditional test method, the test method of the present application does not need to spend several hours waiting for "DO to reach saturation", but only needs to spend 5 to 15 minutes (different due to the size of the ventilation amount) to wait for the OTE reading of the oxygen transfer efficiency detector to be stable, while eliminating the multiple "water injection" and "water discharge" steps in the existing method, and without the need for additional calculation results from the DO rising curve, the present application reduces the labor cost of the clean water oxygen transfer performance test of the aerator from multiple aspects, and reduces the power consumption of the air blower. In addition, by completely collecting the tail gas of the aeration tank, the oxygen transfer performance of the aerator can be more accurately measured, the influence of the bubble touching the probe of the dissolved oxygen meter on the accuracy of the results is completely eliminated, and the influence of the uneven aeration on the accuracy of the results is greatly reduced, so as to improve the accuracy of the test results. BRIEF DESCRIPTION OF DRAWINGS

[0045] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0046] Figure 1 The step schematic diagram of the determination method of the disclosed embodiment of the present application is shown in the figure.

[0047] Figure 2 The schematic diagram of the test device of the disclosed embodiment of the present application is shown in the figure.

[0048] Figure 3 The flow chart of the preparation process of the disclosed embodiment of the present application is shown in the figure.

[0049] Figure 4 The flow chart of the test process of the disclosed embodiment of the present application is shown in the figure.

[0050] Figure 5 The test result diagram of the disclosed embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0051] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0052] Please refer to Figure 1 In the embodiments of the present application, a method for determining the oxygen transmission performance of a water aeration device based on an oxygen transfer efficiency detector, the determination method comprising a preparation process and a test process:

[0053] Step S1, preparation process: setting the water aeration device to be tested, checking whether the system leaks, and confirming whether the air supply capacity of the air blower meets the test requirements and confirming the test conditions, wherein the test conditions include the test water depth H, the aeration rate AFR setting range [AFR min , AFR max ], the bottom area of the test device, and the number of aeration devices installed;

[0054] Step S2, test process: adding catalyst, determining the dissolved oxygen concentration of clean water, adding excess anhydrous Na2SO3, turning on the air blower, waiting for the clean water to be completely deoxygenated, slowly increasing the frequency of the air blower, confirming the preset value of the aeration rate AFR, using the oxygen transfer efficiency detector to sequentially determine the oxygen transfer efficiency OTE corresponding to each AFR setting value, and recording the test data;

[0055] Step S3, after the test is completed, the aeration device OTE-AFR curve is drawn to confirm the oxygen transmission performance of the aeration device under different aeration rates.

[0056] In the specific implementation steps, the specific steps of adding an excess amount of anhydrous Na2SO3 include:

[0057] The amount of anhydrous Na2SO3 added is calculated according to the volume V of the clean water and the initial dissolved oxygen concentration DO0 of the clean water, and the calculation formula is as follows:

[0058]

[0059] Among them, is the amount of anhydrous Na2SO3 added, g; N is the number of set values of the AFR to be measured; DO0 is the initial dissolved oxygen concentration of the clean water, mg / L; K is the safety factor.

[0060] In the specific implementation steps, the specific steps of slowly increasing the frequency of the air blower include:

[0061] Observing whether the offgas_F measured by the oxygen transfer efficiency detector reaches offgas_F min , and whether the AFR measured by the gas flow meter reaches AFR min .

[0062] If both indicators meet the conditions, the frequency of the air blower is fixed; otherwise, the frequency of the air blower is continuously slowly increased.

[0063] In the specific implementation steps, the specific steps of confirming the preset value of the aeration amount AFR include:

[0064] Recording the aeration amount AFR after the current fixed frequency of the air blower as AFR1, as the minimum set value of AFR;

[0065] Setting AFR max as AFR5 as the maximum set value of AFR, then AFR2, AFR3, AFR4 are four equal points in the closed interval [AFR1, AFR5];

[0066] Among them, the preset value of the aeration amount AFR, then the five set values of AFR1, AFR2, AFR3, AFR4, and AFR5 are in order from small to large.

[0067] In the specific implementation steps, the specific steps of using the oxygen transfer efficiency detector to measure the oxygen transfer efficiency OTE corresponding to each AFR set value in turn include starting from AFR1, using each AFR set value for testing in order from small to large, and entering a test cycle.

[0068] In the specific implementation steps, the specific steps of the test cycle include:

[0069] Fixing the frequency of the air blower to the aeration amount AFR n , and continuously aerating;

[0070] When DO obviously rises, add anhydrous Na2SO3, and wait until the clear water is completely deoxygenated, then start the cycle again;

[0071] When DO does not obviously rise, and OTE is still changing, continue to wait until OTE is basically unchanged;

[0072] When DO does not obviously rise, and OTE is basically unchanged within 10 minutes, record the current OTE as OTE n , and record other test data. If there are still AFR set values that have not been tested, adjust the frequency of the air blower until the ventilation AFR is close to AFR n+1 , then enter the next cycle; otherwise, turn off the air blower, empty the clear water, and end the test.

[0073] In the specific implementation steps, the ventilation AFR n is continuously aerated, where AFR n is the nth AFR set value, and the values in the 5 test cycles are AFR1, AFR2, AFR3, AFR4, and AFR5 in order.

[0074] When DO obviously rises, the determination step is:

[0075] DO-DO 消氧后 ≥0.2mg / L

[0076] where DO is the current DO value, mg / L; and DO 消氧后 is the minimum DO value after the complete deoxygenation of the excess anhydrous Na2SO3, mg / L. When the above inequality holds, it is determined that DO obviously rises; otherwise, it is determined that DO does not obviously rise.

[0077] When DO obviously rises, add anhydrous Na2SO3, and the calculation formula for the amount of anhydrous Na2SO3 added is:

[0078]

[0079] where OTE is basically unchanged, and the determination step is:

[0080] OTE 过去10分钟内的最大值 -OTE 过去10分钟内的最小值 <0.1%

[0081] When the above inequality holds, it is determined that OTE is basically unchanged; otherwise, it cannot be determined that OTE is basically unchanged.

[0082] And adjust the frequency of the air blower until the ventilation AFR is close to AFR n+1 , where AFR n+1 refers to the next AFR set value, and the ventilation is close to AFRn+1 The determination method is as follows:

[0083] |AFR-AFR n+1 |<1m 3 / h

[0084] Where AFR is the airflow rate after adjusting the blower frequency, m 3 / h; AFR n+1 Set the value for the next AFR, m 3 / h; when the above inequality holds, it is determined that the ventilation rate (AFR) is close to the average ventilation rate (AFR). n+1 Otherwise, determine that the ventilation rate (AFR) is not close to the average ventilator rate (AFR). n+1 .

[0085] In the specific implementation steps, after the test, the following steps are taken: plot the OTE-AFR curve of the aerator, including plotting OTE as the vertical axis and AFR as the horizontal axis, and plotting 5 groups (AFR... n ,OTE n Plot a scatter plot of the data and fit a power function as follows:

[0086]

[0087] Where p1 and p2 are the parameters of the fitting function.

[0088] like Figure 2 As shown in the diagram, this is a testing device. 1 is a gas collection hood, which collects gas escaping from the liquid surface of the testing device; 2 is a gas delivery hose, which transmits the collected gas to an oxygen transfer efficiency detector; 3 is an oxygen transfer efficiency detector, which analyzes the composition of the escaping gas and determines the oxygen transfer efficiency; 4 is a dissolved oxygen meter, which measures the dissolved oxygen concentration in the water; 5 is a water thermometer, which measures the water temperature; 6 is a blower, which provides airflow based on the target ventilation rate; 7 is a pressure gauge, which measures the relative pressure of the gas and provides airflow information; 8 is an air flow meter, which measures the total ventilation rate; 9 is an aeration pipe, which transmits air; and 10 is an aerator, which disperses the air.

[0089] In this embodiment, blower 6 compresses air to provide aeration. Aeration pipe 9 transmits the compressed air to aerator 10, which disperses the air into the clean water. Gas escaping from the surface of the clean water is collected by gas collection hood 1 and transmitted to oxygen transfer efficiency detector 3 via air guide hose 2. Dissolved oxygen meter 4 measures the dissolved oxygen concentration in the clean water to determine whether oxygen-removing agent needs to be added during the test. Air flow meter 8 measures the total ventilation volume to determine whether the blower's air supply reaches the target ventilation volume for the test. Water thermometer 5 and pressure gauge 7 measure the test water temperature and relative gas pressure, respectively, to record the test conditions.

[0090] like Figure 3 The preparation process shown confirms that the test water depth H is 2.5m and the aerator ventilation rate (AFR) is below the lower limit (AFR). min Take 3m 3 / h, upper limit AFR max Take 10.5m 3 / h, the aerator airflow rate (AFR) setting range is [1.5, 10.5m]. 3 / h], the bottom area A of the test device is 9m² 2 The measured air outlet surface area 'a' of the aerator was 0.283 m². 2 Calculate the number of aerators to be installed according to formula (1):

[0091]

[0092] 1.59 ≤ Number of aerators installed (units) ≤ 3.18

[0093] Two aerators are to be installed.

[0094] Fill the test device with water until aerator 10 is submerged, then stop filling the water supply. Turn on blower 6 and check for leaks in the aeration system, then turn off blower 6. If the aeration system is leak-free, continue with the subsequent steps; otherwise, replace aerator 10 or repair the aeration system and re-check for leaks.

[0095] After completing the leak test of the aeration system, continue filling with water until the water depth reaches H. Then, stop draining the water, turn on blower 6, adjust the frequency of blower 6, and observe whether the AFR can be achieved. max Turn off blower 6. If AFR can reach AFR max If not, continue with the next steps; otherwise, drain the water, replace the blower 6 with one that has a stronger gas supply capacity, and start over from the leak detection step.

[0096] After completing the preparation process, the testing process begins.

[0097] like Figure 4 The test procedure shown involves adding CoSO4·7H2O as a catalyst, with a water volume V of 22.5 m³. 3 Co2+ The ion concentration is taken as 0.3 mg / L. The dosage of CoSO4·7H2O is calculated according to formula (3):

[0098]

[0099] Add 32.2g of CoSO4·7H2O to water, ensuring the solid is fully dissolved during addition.

[0100] The initial dissolved oxygen concentration (DO0) of the purified water was measured to be 7.43 mg / L using a dissolved oxygen meter 4, and the water volume (V) was 22.5 m³. 3 The number of AFR setpoints to be tested, N, is taken as 5, and the safety factor K is taken as 1.35. The dosage of anhydrous Na2SO3 is calculated according to formula (4):

[0101]

[0102] Add 10.67 kg of anhydrous Na2SO3 to clean water.

[0103] Turn on blower 6 and observe the dissolved oxygen concentration (DO) in the water measured by dissolved oxygen meter 4. When the DO concentration drops to 0, slowly increase the frequency of blower 6. The air flow meter 8 first measures an AFR of 1.5 m³ / h. 3 / h, but the exhaust gas flow rate offgas_F measured by the oxygen transfer efficiency detector 3 did not reach 5L / s; continue to slowly increase the frequency of the blower 6 until offgas_F reaches 5L / s, at which point the AFR is approximately 3m 3 / h, then the frequency of the fixed blower is 6.

[0104] Record the current (after fixing the blower frequency) AFR as AFR1 (minimum AFR setting); set AFR max AFR5 is the maximum AFR setting; AFR2, AFR3, and AFR4 are the quartiles of the closed interval [AFR1, AFR5]; the five AFR settings, from smallest to largest, are 3m. 3 / h, 4.9m 3 / h, 6.8m 3 / h, 8.6m 3 / h, 10.5m 3 / h.

[0105] Entering the first test cycle. Maintain a fixed blower frequency of 6 at 3m... 3 With continuous aeration at / h(AFR1), the dissolved oxygen meter 4 measured DO at 0 mg / L throughout. The inequality (5) is calculated as follows:

[0106] DO-DO 消氧后 ≥0.2mg / L#(5)

[0107] 0-0=0<0.2mg / L

[0108] Inequality (5) is not true, and it is determined that DO does not increase significantly. When the oxygen transfer efficiency detector 3 determines that the oxygen transfer efficiency OTE does not change significantly, OTE is 14.49%, and 14.49% is recorded as OTE1. The water temperature meter 5 reads 22.7°C, and the pressure gauge 7 reads 21.5 kPa. The frequency of the air blower 6 is adjusted so that the AFR measured by the gas flow meter 8 reaches 4.3 m 3 / h, and Inequality (8) is calculated as follows:

[0109] |AFR-AFR n+1 |<1m 3 / h#(8)

[0110] |4.3-4.9|=0.6<1m 3 / h

[0111] Inequality (8) is true, and it is determined that the ventilation AFR is close to AFR n+1 , and the next cycle is entered.

[0112] The second test cycle is entered. The frequency of the air blower 6 is fixed at 4.3 m 3 / h (close to AFR2) to continue aeration, and the DO measured by the dissolved oxygen meter 4 is always 0 mg / L, and Inequality (5) is calculated as follows:

[0113] DO-DO 消氧后 ≥0.2mg / L#(5)

[0114] 0-0=0<0.2mg / L

[0115] Inequality (5) is not true, and it is determined that DO does not increase significantly. When the oxygen transfer efficiency detector 3 determines that the oxygen transfer efficiency OTE does not change significantly, OTE is 12.52%, and 12.52% is recorded as OTE2. The water temperature meter 5 reads 22.7°C, and the pressure gauge 7 reads 22.4 kPa. The frequency of the air blower 6 is adjusted so that the AFR measured by the gas flow meter 8 reaches 6.4 m 3 / h, and Inequality (8) is calculated as follows:

[0116] |AFR-AFR n+1 |<1m 3 / h#(8)

[0117] |6.4-6.8|=0.4<1m 3 / h

[0118] Inequality (8) is true, and it is determined that the ventilation AFR is close to AFR n+1 , and the next cycle is entered.

[0119] / h (close to AFR3) continuously, the DO measured by the dissolved oxygen meter 4 is always 0 mg / L, and the inequality (5) is calculated as follows: 3 / h (close to AFR3) continuously, the DO measured by the dissolved oxygen meter 4 is always 0 mg / L, and the inequality (5) is calculated as follows:

[0120] Do-Do 消氧后 ≥0.2mg / L#(5)

[0121] 0-0=0<0.2mg / L

[0122] The inequality (5) is not established, and it is determined that the DO does not rise obviously. When the oxygen transfer efficiency detector 3 measures that the oxygen transfer efficiency OTE is basically unchanged, the OTE is 10.75%, and 10.75% is recorded as OTE3. The reading of the water temperature meter 5 is recorded as 22.6℃, and the reading of the pressure gauge 7 is recorded as 22.9 kPa. The frequency of the air blower 6 is adjusted so that the AFR measured by the gas flow meter 8 reaches 8.1 m 3 / h (close to AFR3) continuously, the DO measured by the dissolved oxygen meter 4 is always 0 mg / L, and the inequality (5) is calculated as follows:

[0123] |AFR-AFR n+1 |<1m 3 / h#(8)

[0124] |8.1-8.6|=0.5<1m 3 / h

[0125] The inequality (8) is established, and it is determined that the ventilation AFR is close to AFR n+1 , and the next cycle is entered.

[0126] The fourth test cycle is entered. The frequency of the air blower 6 is fixed at 8.1 m 3 / h (close to AFR3) continuously, and the DO measured by the dissolved oxygen meter 4 reaches 1.6 mg / L during the process, and the inequality (5) is calculated as follows:

[0127] DO-DO 消氧后 ≥0.2mg / L#(5)

[0128] 1.6-0=1.6≥0.2mg / L

[0129] The inequality (5) is established, and it is determined that the DO rises obviously. The anhydrous Na2SO3 dosage is calculated according to formula (6):

[0130]

[0131] 1.778 kg of anhydrous Na2SO3 is added to the clean water, and the dissolved oxygen concentration DO measured by the dissolved oxygen meter 4 is observed to be reduced to 0, and this cycle is restarted.

[0132] The fourth test cycle is re-entered. The frequency of the air blower 6 is fixed at 8.1 m3 / h (near AFR3) continuously, the dissolved oxygen meter 4 determines DO to be always 0 mg / L, and the inequality (5) is calculated as follows:

[0133] DO - DO 消氧后 ≥ 0.2 mg / L (5)

[0134] 0 - 0 = 0 < 0.2 mg / L

[0135] The inequality (5) is not established, and it is determined that DO does not significantly rise. When the oxygen transfer efficiency detector 3 determines that the oxygen transfer efficiency OTE is substantially unchanged, OTE is 10.21%, and 10.21% is recorded as OTE4. The water thermometer 5 is recorded to be 22.6°C, and the pressure gauge 7 is recorded to be 21.5 kPa. The frequency of the air blower 6 is adjusted so that the AFR determined by the gas flow meter 8 reaches 9.8 m 3 / h, and the inequality (8) is calculated as follows:

[0136] | AFR - AFR n+1 | < 1 m 3 / h (8)

[0137] | 9.8 - 10.5 | = 0.7 < 1 m 3 / h

[0138] The inequality (8) is established, and it is determined that the aeration amount AFR is near AFR n+1 , and the next cycle is entered.

[0139] The 5th test cycle is entered. The frequency of the air blower 6 is fixed at 9.8 m 3 / h (near AFR3) continuously, the dissolved oxygen meter 4 determines DO to be always 0 mg / L, and the inequality (5) is calculated as follows:

[0140] DO - DO 消氧后 ≥ 0.2 mg / L (5)

[0141] 0 - 0 = 0 < 0.2 mg / L

[0142] The inequality (5) is not established, and it is determined that DO does not significantly rise. When the oxygen transfer efficiency detector 3 determines that the oxygen transfer efficiency OTE is substantially unchanged, OTE is 9.83%, and 9.83% is recorded as OTE5. The water thermometer 5 is recorded to be 22.6°C, and the pressure gauge 7 is recorded to be 21.1 kPa.

[0143] Up to now, it is confirmed that AFR1, AFR2, AFR3, AFR4, AFR5 are 3 m 3 / h, 4.3 m 3 / h, 6.4 m 3 / h, 8.1 m 3 / h, 9.8 m3 OTE1, OTE2, OTE3, OTE4, OTE5 are 14.49%, 12.52%, 10.75%, 10.21%, 9.83%, respectively.

[0144] Close the blower, empty the clean water, and the test is over.

[0145] Take OTE as the longitudinal coordinate, AFR as the horizontal coordinate, draw a scatter plot with 5 groups (AFR n , OTE n ) data, and fit a power function. Figure 5 The test result graph is shown in the figure.

[0146] The aeration device performance curve in the test result graph directly reflects the clean water oxygen transfer performance of the aeration device under different aeration rates.

[0147] The test of the embodiment of the application takes 2 working days in total, the first working day is used for water discharge of the test device, and the second working day is used for aeration test and water discharge of the test device, wherein the blower aeration time is 3h, and 5 groups (AFR n , OTE n ) data are measured. Under the same test scale, if the traditional method is used to measure the oxygen transfer performance of the aeration device under 5 aeration rates, the water discharge of the test device takes 1 working day, the aeration test and the water discharge of the test device take 1 working day, and at least 10 working days are required; the single aeration time is about 4h, and the total aeration time is about 20h.

[0148] Therefore, it is estimated that under the same test scale, the test time of the embodiment of the application is about 20% of the traditional method, which can greatly reduce the labor cost; secondly, the aeration time of the embodiment of the application is about 15% of the traditional method, which reduces the power consumption of the blower; and the OTE can be directly measured, without the need to calculate the clean water oxygen transfer performance of the aeration device according to the DO rising curve, without the need for additional data processing, further reducing the labor cost; in addition, by completely collecting the tail gas of the aeration tank, the oxygen transfer performance of the aeration device can be more accurately measured, completely eliminating the influence of the touch of the bubble on the probe of the dissolved oxygen meter on the accuracy of the results, while greatly reducing the influence of uneven aeration on the accuracy of the results, improving the accuracy of the test results.

[0149] Although the embodiments of the application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and spirits of the application, the scope of the application is defined by the appended claims and their equivalents, and all should be included in the protection scope of the application.

Claims

1. A method for determining the oxygen transfer performance of an aerator in clear water based on an oxygen transfer efficiency detector, characterized in that, The determination method includes a preparation process and a testing process: Step S1, Preparation: Set up the aerator to be tested, check for air leaks in the system, and confirm that the blower's air supply capacity meets the test requirements. Confirm the test conditions, including the test water depth H and the aerator's airflow rate (AFR) setting range [AFR]. min AFR max The test device's bottom area and the number of aerators installed; Step S2, Test process: Add catalyst, measure dissolved oxygen concentration in water, add excess anhydrous Na2SO3, turn on blower, wait for complete deoxygenation of water, slowly increase blower frequency, confirm the preset value of aerator air flow rate (AFR), use oxygen transfer efficiency tester to measure the oxygen transfer efficiency (OTE) corresponding to each AFR setting value in sequence, and record the test data. The specific steps for slowly increasing the blower frequency include: Observe whether the exhaust gas flow rate offgas_F measured by the oxygen transfer efficiency detector reaches offgas_F. min And whether the AFR measured by the gas flow meter reaches the AFR min If both indicators meet the conditions, fix the blower frequency; otherwise, continue to slowly increase the blower frequency. The specific steps for confirming the preset value of the aerator airflow rate (AFR) include: Record the aerator airflow rate (AFR) after fixing the blower frequency as AFR1, which will be used as the minimum AFR setting value; set AFR max If AFR5 is taken as the maximum set value of AFR, then AFR2, AFR3, and AFR4 are the four quartiles of the closed interval [AFR1, AFR5]. Among them, the preset values ​​of the aerator ventilation volume AFR are, in ascending order, the five set values ​​of AFR1, AFR2, AFR3, AFR4, and AFR5. The specific steps for using the oxygen transfer efficiency detector to sequentially measure the oxygen transfer efficiency (OTE) corresponding to each AFR set value include: starting from AFR1, testing each AFR set value in sequence from small to large, and entering the test cycle. The specific steps of the test loop include: With a fixed blower frequency, the airflow rate (AFR) is used to measure the airflow rate. n Continuous aeration; When the dissolved oxygen (DO) level rises significantly, add anhydrous Na2SO3, wait for the water to be completely deoxygenated, and then restart the cycle. If DO does not increase significantly and the oxygen transfer efficiency (OTE) is still changing, continue to wait until OTE remains essentially constant. When DO does not increase significantly and the oxygen transfer efficiency (OTE) remains essentially unchanged within 10 minutes, record the current OTE as OTE. n Record other test data. If there are still untested AFR settings, adjust the blower frequency until the ventilation AFR is close to the AFR. n+1 If the test is successful, proceed to the next cycle; otherwise, turn off the blower, drain the water, and end the test. Step S3: After the test, plot the OTE-AFR curve of the aerator to confirm the oxygen transfer performance of the aerator in clear water under different aeration conditions.

2. The method for determining the oxygen transfer performance of an aerator in clear water based on an oxygen transfer efficiency detector according to claim 1, characterized in that, The specific steps for adding excess anhydrous Na2SO3 include: Based on the volume V of the clear water and the initial dissolved oxygen concentration of the clear water The dosage of anhydrous Na2SO3 is calculated using the following formula: in, The dosage of anhydrous Na2SO3 is in g; The number of AFR values ​​to be measured; The initial dissolved oxygen concentration in the water is mg / L. This is for the safety factor.

3. The method for determining the oxygen transfer performance of an aerator in clear water based on an oxygen transfer efficiency detector according to claim 1, characterized in that, The ventilation rate AFR n Continuous aeration, including AFR n The nth AFR is set to a value, and in 5 test cycles, the values ​​are AFR1, AFR2, AFR3, AFR4, and AFR5 respectively. When DO rises significantly, the determination steps are as follows: in, This is the current DO value, in mg / L; The minimum DO value after complete deoxygenation with excess anhydrous Na2SO3 is given, in mg / L; when the above inequality holds, it is determined that DO has increased significantly; otherwise, it is determined that DO has not increased significantly. When the dissolved oxygen (DO) level rises significantly, anhydrous Na₂SO₃ is added. The formula for calculating the amount of anhydrous Na₂SO₃ added is: in, The dosage of anhydrous Na2SO3 is in g; The volume of pure water; The initial dissolved oxygen concentration in the water is mg / L. For safety margin; the oxygen transfer efficiency (OTE) remains essentially unchanged, the determination steps are as follows: When the above inequality holds, it is determined that OTE remains essentially unchanged; otherwise, it cannot be determined that OTE remains essentially unchanged. Adjust the blower frequency until the airflow rate (AFR) is close to the airflow rate (AFR). n+1 , among which, AFR n+1 This refers to the next AFR setting, where the ventilation rate is close to the AFR. n+1 The determination method is as follows: in, To adjust the airflow after adjusting the blower frequency, m 3 / h; Set the value for the next AFR, m 3 / h; when the above inequality holds, it is determined that the ventilation rate (AFR) is close to the average ventilation rate (AFR). n+1 Otherwise, determine that the ventilation rate (AFR) is not close to the average ventilator rate (AFR). n+1 .

4. The method for determining the oxygen transfer performance of an aerator in clear water based on an oxygen transfer efficiency detector according to claim 1, characterized in that, The specific steps after the test are as follows: plot the OTE-AFR curve of the aerator, including plotting OTE as the vertical axis and AFR as the horizontal axis, and using 5 groups (AFR... n OTE n Plot a scatter plot of the data and fit a power function as follows: in, , These are the parameters of the fitted function.

Images