A method for evaluating aeration performance of a device for mixing oxygen-containing gas and aqueous solution

Abstract

The present invention provides an aeration performance evaluation method for an oxygen-containing gas and aqueous solution mixing device, comprising the following steps: determining the oxygen content in the input oxygen-containing gas, the flow rate of the circulating pump of the device to be tested, and the cycle frequency of a single test experiment, and obtaining the volume of the aqueous solution under the test conditions; opening the device to be tested to circulate the aqueous solution in the test container, adding an oxygen scavenger, and adjusting the gas flow rate to input the oxygen-containing gas into the aqueous solution; recording the dissolved oxygen and the corresponding time values; repeating the above steps to obtain the dissolved oxygen values ​​under different cycle frequencies and different liquid-to-gas ratios; calculating a series of aeration performance parameters and drawing a graph or table. At the same time, the method of the present invention can also obtain aeration performance parameter charts of different equipment under different liquid-to-gas ratio conditions at a certain cycle frequency, and compare them. Under the actual industrial process requirements, the method of the present invention has guiding significance for the design of equipment and processes in the production process.

Description

Technical Field

[0001] The invention relates to the technical field of equipment performance evaluation, and in particular to an aeration performance evaluation method for an oxygen-containing gas and aqueous solution mixing device. Background Art

[0002] Aerators are widely used in the urban construction industry, especially in the water treatment industry. Aerators dissolve oxygen in gas (usually air) into water by bringing gas (usually air) into contact with water. The performance of aerators can be measured by detecting the concentration of dissolved oxygen.

[0003] The current measurement method for the oxygen mass transfer performance of aerators (such as in standard CJ / T475-2015) is to aerate and measure the change curve of dissolved oxygen in the water over time, and calculate the standard oxygen total mass transfer coefficient, standard oxygen mass transfer rate, standard oxygen mass transfer efficiency and standard aeration efficiency of the aerator.

[0004] In order to meet the data obtained in the experiment, the standard CJ / T475-2015 has made the following limiting conditions. First, the water in the test pool does not flow in or out, which is a non-steady-state measurement method. Second, only the detection of dissolved oxygen at three different depths of the test volume is considered, and the volume required for the test is not specified. Third, the aerators applicable in this standard are generally microporous aerators or air aerators. This type of aeration method only involves gas being blown into the water through micropores or tube holes. Generally, only the ratio of the aerator outlet surface area to the bottom area of ​​the test device is considered, and other methods of gas-liquid mixing are not considered.

[0005] The current measurement methods of aerator oxygen mass transfer performance have the following shortcomings:

[0006] 1) Most of the existing industrial aeration methods use ejectors, gas-liquid mixing pumps, venturi tubes, membrane aeration, etc. Almost all of these methods require the use of pumps as power. The pump circulates the liquid, and the gas and liquid are mixed through various air intake forms during the pump circulation process to obtain a water flow containing gas, thereby increasing the oxygen content of the water body. Therefore, we must consider the pump circulation factor and introduce new condition parameters to obtain a method for evaluating aeration performance and oxygen mass transfer performance that is of practical significance.

[0007] Due to the introduction of the pump, it is necessary to consider the pump's circulation volume, energy consumption, the relationship between the pump's circulation volume and the test water volume, the proportional relationship between the pump's circulation volume and the air intake volume, etc. However, the existing methods do not consider the significant changes these factors bring to oxygen mass transfer.

[0008] 2) The existing standard test method only considers air as the gas source, and does not consider the impact of gas sources with different oxygen contents on the aeration process performance. Therefore, in order to obtain a method with more engineering guidance significance, it is necessary to consider the impact of gas sources with different oxygen contents on aeration performance.

[0009] 3) For equipment of different models, specifications and sizes, the equipment parameters and performance are not uniform. We need to establish a fair evaluation method to meet the requirements of comparison and evaluation of different equipment under relatively the same conditions.

[0010] The existing standards only introduce the testing and calculation methods, but do not limit the testing conditions and the different equipment in different water tanks. This will lead to different performance parameter results of the aerator under different conditions, and the results have no practical guiding significance. Summary of the invention

[0011] In order to overcome the deficiencies of the prior art, the object of the present invention is to provide a method for evaluating the aeration performance of a device for mixing oxygen-containing gas and aqueous solution.

[0012] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0013] The present application provides a method for evaluating the aeration performance of an oxygen-containing gas and aqueous solution mixing device, comprising the following steps:

[0014] S1. Determine the oxygen content in the input oxygen-containing gas;

[0015] S2. Determine the circulation pump flow rate of the device to be tested;

[0016] S3. Determine the cycle frequency of a single test experiment of the device to be evaluated, and obtain the volume of the aqueous solution under the test conditions according to the circulation pump flow rate and the circulation frequency; the circulation frequency is the ratio of the circulation pump flow rate of the device to be tested to the volume of the aqueous solution under the test conditions;

[0017] S4. Turn on the device to be tested to circulate the aqueous solution in the test container, add an oxygen scavenger so that the dissolved oxygen in the aqueous solution is less than 0.5 mg / L and stabilized, and then adjust the gas flow rate to input oxygen-containing gas into the aqueous solution;

[0018] S5. Record the dissolved oxygen and corresponding time values;

[0019] S6. Repeat steps S1-S5 to obtain dissolved oxygen values ​​that vary over time at different circulation frequencies and different liquid-gas ratios; the liquid-gas ratio is the ratio of the circulation pump flow rate to the oxygen-containing gas flow rate;

[0020] S7. Calculate the series of aeration performance parameters of the oxygen-containing gas and aqueous solution mixing device under different cycle frequencies and different liquid-gas ratios according to the dissolved oxygen value; and draw a graph or table of each aeration performance parameter with the liquid-gas ratio as the abscissa and the aeration performance parameter as the ordinate; the aeration performance parameters include K L a. At least one of SOTR, SOTE, and SAE.

[0021] The cycle frequency and liquid-to-gas ratio described in the present invention are dimensionless parameters.

[0022] In one embodiment of the present invention, in step S1, the oxygen content is any one of volume percentage, mole percentage or mass percentage;

[0023] In step S3, the aqueous solution is any one of pure water, clean water, and tap water, and its water quality index TDS should be less than 2000 mg / L.

[0024] In one embodiment of the present invention, in step S3, the cycle frequency is 0.01-100;

[0025] The oxygen-containing gas and aqueous solution mixing device is a device with a gas-liquid mixing function, including any one of a jet aerator, a gas-liquid mixing pump, a venturi tube, a membrane aeration, and a micro-nano bubble device, but not limited thereto.

[0026] In one embodiment of the present invention, in step S7, K is calculated according to the following formulas (1)-(10): L a. SOTR, SOTE, SAE:

[0027]

[0028] In formula (1), C is the dissolved oxygen concentration in water corresponding to aeration time t, mg / L; t is time, min; C0 is the dissolved oxygen concentration corresponding to time 0, mg / L; is the dissolved oxygen concentration value when reaching steady state, mg / L; K L a is the oxygen mass transfer coefficient, 1 / min;

[0029]

[0030] K L a s =K L a×θ 20-T (3)

[0031]

[0032] In formulas (2)-(6), SOTR is the standard oxygen mass transfer rate, kg / h; K L as is the total oxygen mass transfer coefficient under standard state and test conditions, 1 / min; is the saturated dissolved oxygen concentration value of the test point under standard conditions, mg / L; V is the volume of the aqueous solution in the test container, m 3 ; θ is the empirical coefficient of temperature correction, which is 1.024; T is the average water temperature during the test, ℃; is the dissolved oxygen concentration value when reaching steady state, mg / L; τ is the temperature correction coefficient; Ω is the pressure correction factor; It is the saturated dissolved oxygen concentration value at 101.235 kPa atmospheric pressure and test water temperature, mg / L; is the saturated dissolved oxygen concentration value under standard conditions, mg / L; P b is the absolute pressure of the gas during the test, kPa; P b0 101.235 kPa;

[0033]

[0034]

[0035] In formulas (7)-(8), SOTE is the standard oxygen mass transfer efficiency, %; Wo2 is the mass flow rate of oxygen in the oxygen-containing gas, kg / h; ρ is the density of the oxygen-containing gas at the test temperature, kg / m 3 ;Q b is the actual flow rate of oxygen-containing gas, m 3 / h; Vol% (oxygen) is the mass percentage of oxygen in the gas;

[0036]

[0037] P=P1+P2 (10)

[0038] In formulas (9)-(10), SAE is the standard aeration efficiency, kg / (kW·h); P is the total power required by the device to be tested, KW; P1 is the actual power required for the circulation of the aqueous solution, KW; P2 is the sum of the power converted from the preparation cost of the oxygen-containing gas and the actual power required for the process of entering the device, KW.

[0039] In the calculation formula of the present invention, since gases with different oxygen contents are used as the gas source and are not limited to air as the gas source, the calculation formula of SOTE is modified to form the above formulas (7) and (8).

[0040] In the calculation formula of the present invention, since the aqueous solution used is a circulating aqueous solution, the power of the pump needs to be considered, and the total power of other auxiliary equipment such as oxygen generators and pressurizers needs to be considered. Therefore, the above formula (10) needs to be used to calculate the total power required for the test device, and then the SAE value is obtained.

[0041] By comparing the differences in aeration performance parameters under different liquid-gas ratios using the above evaluation method, the following results can be obtained:

[0042] 1) Under a certain liquid-gas ratio and a certain oxygen concentration, the SOTR standard oxygen mass transfer rate is the highest (which is of guiding significance when the system pursues rapid dissolution of dissolved oxygen);

[0043] 2) Under certain liquid-gas ratio and oxygen concentration conditions, SOTE standard oxygen mass transfer efficiency is the highest (which is of guiding significance when the system pursues oxygen utilization rate);

[0044] 3) Under certain liquid-gas ratio and oxygen concentration conditions, SAE standard aeration efficiency is the highest (when the system does not have very high requirements for the dissolution speed and utilization rate of oxygen, and requires a certain degree of economy, it has guiding significance).

[0045] The present invention also provides a method for evaluating the aeration performance of multiple oxygen-containing gas and aqueous solution mixing devices, comprising the following steps:

[0046] A1. According to the above method, a series of aeration performance parameters of multiple oxygen-containing gas and aqueous solution mixing devices at multiple cycle frequencies and different liquid-gas ratios are obtained;

[0047] A2. Select a series of aeration performance parameters of multiple oxygen-containing gas and aqueous solution mixing devices at different liquid-to-gas ratios under a certain cycle frequency, draw a graph or table with a single aeration performance parameter as the ordinate and the liquid-to-gas ratio as the abscissa, and obtain comparative characteristics of two or more sets of oxygen-containing gas and aqueous solution mixing devices under a single or multiple aeration performance parameters.

[0048] In one embodiment of the present invention, the plurality of oxygen-containing gas and aqueous solution mixing devices are devices with different pump circulation volumes and / or different gas flow rates;

[0049] Each of the oxygen-containing gas and aqueous solution mixing devices is a device with a gas-liquid mixing function, including any one of a jet aerator, a gas-liquid mixing pump, a venturi tube, a membrane aeration, and a micro-nano bubble device, but not limited thereto.

[0050] In one embodiment of the present invention, in step A1, the cycle frequency is 0.01-100; and the liquid-gas ratio is 0.2-200.

[0051] The present invention also provides an application of the aforementioned evaluation method in designing a system based on a device for mixing oxygen-containing gas and aqueous solution, wherein the application fields of the system include at least one of aquaculture, rice cultivation, oxygenation of lakes and rivers, advanced ozone oxidation, domestic sewage treatment, petrochemical sewage treatment, and supercritical fluid.

[0052] The present invention obtains a chart of aeration performance parameters based on the above method, and obtains the applicable range of aeration performance parameters of an oxygen-containing gas and aqueous solution mixing device under a certain cycle frequency and a certain liquid-to-gas ratio under different application scenarios, thereby providing guidance for the design of the device for application in different actual production processes.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] 1. The present invention provides an evaluation method for the aeration performance of an oxygen-containing gas and aqueous solution mixing device. Due to the presence of a circulating pump, the water body circulates, and thus two parameter conditions, liquid-gas ratio and circulation frequency, are proposed for the first time. The circulation frequency is designed during the experiment to determine the experimental water volume, and then the gas flow rate is adjusted to change the liquid-gas ratio, and experiments are conducted under different liquid-gas ratios, thereby obtaining aeration performance parameters under different circulation frequencies and different liquid-gas ratios.

[0055] 2. The present invention determines the test conditions by designing the cycle frequency, and by setting up a simulation system, the operating conditions of the aerator are more in line with the actual application situation. By using this method for evaluation, the operating parameters that are most suitable for the system can be obtained, which is more representative for the system that needs to be applied. By adjusting the liquid-gas ratio, the application conditions that are more suitable for the system are found. It is not a simple evaluation of the equipment performance, but an evaluation of all situations, and then the most suitable operating parameters are selected according to the purpose. In actual engineering, the application of the equipment is further analyzed, which has engineering significance. The obtained liquid-gas ratio can be used directly in the design to avoid the performance effect of the equipment not being consistent with expectations, which makes the performance evaluation of the equipment deviate during the design, causing engineering losses and delays in the construction period. This evaluation method uniformly defines the conditions and can also provide fair comparison conditions when selecting an aerator. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0057] Figure 1 The SOTE curves obtained at different liquid-gas ratios using the evaluation method of Example 1 of the present invention;

[0058] Figure 2 The SOTR curves obtained at different liquid-gas ratios using the evaluation method of Example 1 of the present invention;

[0059] Figure 3 The SAE curves obtained at different liquid-gas ratios using the evaluation method of Example 1 of the present invention;

[0060] Figure 4 The SOTR curves obtained at different liquid-gas ratios using the evaluation method of Example 2 of the present invention;

[0061] Figure 5 The SOTE curves obtained at different liquid-gas ratios using the evaluation method of Example 2 of the present invention;

[0062] Figure 6 The SAE curves obtained at different liquid-gas ratios using the evaluation method of Example 2 of the present invention;

[0063] Figure 7 The SOTR curves obtained at different liquid-gas ratios using the evaluation method of Example 3 of the present invention;

[0064] Figure 8 The SOTE curves obtained at different liquid-gas ratios using the evaluation method of Example 3 of the present invention;

[0065] Fig. 9 The SAE curves obtained at different liquid-gas ratios using the evaluation method of Example 3 of the present invention;

[0066] Fig.10 The SOTR curves obtained at different liquid-gas ratios using the evaluation method of Example 4 of the present invention;

[0067] Fig.11 The SOTE curves obtained at different liquid-gas ratios using the evaluation method of Example 4 of the present invention;

[0068] Fig.12 The SAE curves obtained at different liquid-gas ratios using the evaluation method of Example 4 of the present invention;

[0069] Fig.13 The SOTR comparison curves obtained at different liquid-gas ratios using the evaluation methods of Examples 2 and 4 of the present invention;

[0070] Fig.14 The SOTE comparison curves obtained at different liquid-gas ratios using the evaluation methods of Examples 2 and 4 of the present invention;

[0071] Fig.15 The SAE comparison curves obtained at different liquid-gas ratios using the evaluation methods of Examples 2 and 4 of the present invention;

[0072] Fig.16 The SOTR curves obtained at different liquid-gas ratios using the evaluation method of Example 5 of the present invention;

[0073] Fig.17 The SOTE curves obtained at different liquid-gas ratios using the evaluation method of Example 5 of the present invention;

[0074] Fig.18 The SAE curves obtained at different liquid-gas ratios using the evaluation method of Example 5 of the present invention;

[0075] Fig.19 The SOTR comparison curves obtained at different liquid-gas ratios using the evaluation methods of Examples 2 and 5 of the present invention;

[0076] Fig. 20 The SOTE comparison curves obtained at different liquid-gas ratios using the evaluation methods of Examples 2 and 5 of the present invention;

[0077] Fig.21 The SAE comparison curves are obtained at different liquid-to-gas ratios using the evaluation methods of Examples 2 and 5 of the present invention. DETAILED DESCRIPTION

[0078] Unless otherwise defined, technical terms or scientific terms used in this specification and claims shall have the ordinary meanings understood by persons with ordinary skills in the technical field to which this application belongs. All values ​​from the lowest value to the highest value listed herein refer to all values ​​obtained by incrementing the lowest value to the highest value by one unit when the difference between the lowest value and the highest value is more than two units.

[0079] The specific implementation methods of the present application will be described below. It should be noted that in the specific description of these implementation methods, in order to provide a concise description, it is impossible for this specification to provide a detailed description of all the features of the actual implementation methods. Without departing from the spirit and scope of the present application, those skilled in the art may modify and replace the implementation methods of the present application, and the resulting implementation methods are also within the scope of protection of the present application.

[0080] In the evaluation method of the following embodiments, the dissolved oxygen test device is placed at a position where the liquid flows and will not be affected by the outlet of the oxygen-containing gas and aqueous solution mixing device, and the dissolved oxygen test device needs to be calibrated before testing.

[0081] In the evaluation method of the following embodiments, the test water is tap water with a TDS not exceeding 2000 mg / L. The test water temperature is preferably between 10°C and 30°C, preferably at 20°C. During a single test experiment, the water temperature change should not be greater than 2°C.

[0082] In the evaluation method of the following embodiment, it is necessary to add a reagent to the aqueous solution, which is the same as the existing standard method, specifically including:

[0083] 1) Catalyst addition

[0084] The catalyst is chemically pure or reagent pure cobalt chloride hydrate (CoCl2·6H2O) or cobalt sulfate (CoSO4). The cobalt ion concentration in the water should be maintained at 0.10mg / L to 0.50mg / L. After the catalyst is prepared into a solution, it is evenly added to the test device. If the test water is not changed during the test, the catalyst can be added once.

[0085] 2) Sodium sulfite addition

[0086] The deoxidizer should be reagent-pure or industrial-pure sodium sulfite, and cobalt impurities should not be contained in the sodium sulfite. After adding the deoxidizer, the time for the dissolved oxygen concentration to drop below 0.50 mg / L should be greater than 2 minutes. Sodium sulfite should be added in the form of a solution, and the amount of the solution should not exceed 0.2% of the test water volume. Powdered agents can also be added directly to ensure that the agent is evenly dispersed in the water. The dosage calculation formula for sodium sulfite is:

[0087] G=7.88×V×C×K

[0088] Where: G is the dosage of sodium sulfite, g; V is the volume of the aqueous solution in the test container, m 3 ; C is the dissolved oxygen concentration in the aqueous solution during the test, mg / L; K is the safety factor considering impurities in the reagent, which can be 1.20~1.50.

[0089] In the evaluation method of the following embodiments, the cycle frequency is the ratio of the liquid flow rate of the circulating pump of the device to be tested in one hour (i.e., the circulating pump flow rate) to the volume of the aqueous solution in the test container; the liquid-gas ratio is the ratio of the liquid flow rate of the circulating pump to the oxygen-containing gas flow rate under the same unit time; both are dimensionless parameters. The physical meaning of the cycle frequency is: the number of times a certain pool of water passes through a pump with a certain circulation flow rate per unit time (for example, the design test experiment cycle frequency is 5, the liquid flow rate of the circulating pump of the device to be tested is 500L / h, and the volume of water in the pool of the device to be tested for the experiment is 100L).

[0090] Example

[0091] The embodiments of the present application will be described in detail below. This embodiment is implemented on the premise of the technical solution of the present application, and a detailed implementation method and a specific operation process are given, but the protection scope of the present application is not limited to the following embodiments.

[0092] Example 1

[0093] This embodiment provides an evaluation method for the aeration performance of an oxygen-containing gas and aqueous solution mixing device. The gas source used is air (oxygen volume percentage is 21%), and the oxygen-containing gas and aqueous solution mixing device used is a nano bubble aerator (model OXYDEEP-0.3). The specific evaluation method is as follows:

[0094] 1) Install the device to be tested and the test water tank. The detection method adopts the non-steady-state measurement method, and the water in the water tank circulates through the circulation pump of the device to be tested.

[0095] 2) The liquid flow rate of the circulation pump is 200L / h. The designed circulation frequency parameter is 13.5, and the volume of water in the water tank is 15L.

[0096] 3) Pour 15L of clean water into the water tank and record the clean water temperature, TDS and initial DO value.

[0097] 4) Add the catalyst cobalt chloride hexahydrate and deoxidizer sodium sulfite into the water tank. Use industrial grade sodium sulfite (Na2SO3), which is dissolved in water and oxidized to sodium sulfate (Na2SO4). Take water through the water tank sampling port, dissolve the cobalt chloride hexahydrate, add it to the water tank, and then add sodium sulfite to make the DO value of the clean water lower than 0.5mg / L.

[0098] 5) Turn on the circulation pump (operating power is 200W), adjust the gas flow rate to 0.1-0.4L / min (liquid-gas ratio is 33.10-8.73), and allow the nano bubble aerator to aerate.

[0099] 6) Use a dissolved oxygen testing device to record the changes in dissolved oxygen over time.

[0100] 7) Record other data.

[0101] 8) Based on the obtained data, substitute it into the following formulas (1)-(10) to calculate the aeration performance parameter K: L a. Values ​​of SOTR, SOTE and SAE.

[0102]

[0103] In formula (1), C is the dissolved oxygen concentration in water corresponding to aeration time t, mg / L; t is time, min; C0 is the dissolved oxygen concentration corresponding to time 0, mg / L; is the dissolved oxygen concentration value when reaching steady state, mg / L; K L a is the oxygen mass transfer coefficient, 1 / min;

[0104]

[0105] K L as =K L a×θ 20-T (3)

[0106]

[0107] In formulas (2)-(6), SOTR is the standard oxygen mass transfer rate, kg / h; K L a s is the total oxygen mass transfer coefficient under standard state and test conditions, 1 / min; is the saturated dissolved oxygen concentration value of the test point under standard conditions, mg / L; V is the volume of the aqueous solution in the test container, m 3 ; θ is the empirical coefficient of temperature correction, which is 1.024; T is the average water temperature during the test, ℃; is the dissolved oxygen concentration value when reaching steady state, mg / L; τ is the temperature correction coefficient; Ω is the pressure correction factor; It is the saturated dissolved oxygen concentration value at 101.235 kPa atmospheric pressure and test water temperature, mg / L; is the saturated dissolved oxygen concentration value under standard conditions, mg / L; P b is the absolute pressure of the gas during the test, kPa; P b0 101.235 kPa;

[0108]

[0109]

[0110] In formulas (7)-(8), SOTE is the standard oxygen mass transfer efficiency, %; Wo2 is the mass flow rate of oxygen in the oxygen-containing gas, kg / h; ρ is the density of the oxygen-containing gas at the test temperature, kg / m 3 ;Q b is the actual flow rate of oxygen-containing gas, m 3 / h; Vol% (oxygen) is the mass percentage of oxygen in the gas;

[0111]

[0112] P=P1+P2 (10)

[0113] In formulas (9)-(10), SAE is the standard aeration efficiency, kg / (kW·h); P is the total power required by the device to be tested, KW; P1 is the actual power required for the circulation of the aqueous solution, W; and P2 is the sum of the power converted from the preparation cost of the oxygen-containing gas and the actual power required for the process of entering the device, W.

[0114] Using different gas flow rates q bThe calculated results of various aeration performance parameter indicators are shown in Table 1.

[0115] Table 1

[0116]

[0117]

[0118] With the liquid-gas ratio in Table 1 as the horizontal axis and SOTE, SOTR, and SAE as the vertical axis, curve graphs are drawn respectively, such as Figure 1-Figure 3 As shown. Figure 1-Figure 3 It can be seen that under different liquid-gas ratio conditions, the trends of SOTE, SOTR and SAE are not the same. Under the working condition that requires a rapid increase in dissolved oxygen, the higher the SOTR, the better the effect. It can also be seen in the figure that when the liquid-gas ratio is lower, the SOTR value is higher. You can choose the upper limit of the liquid-gas ratio that the equipment allows for aeration, and SOTR is the highest at this time; when it is necessary to meet high gas utilization efficiency, you can choose to aerate in the range of relatively high liquid and gas that the equipment can withstand, and SOTE is the highest at this time; when considering economic benefits and aeration efficiency, you can also compare the gains of different parameters. Under the condition of meeting the working conditions, choose the liquid-gas ratio with the highest SAE for aeration.

[0119] Example 2

[0120] This embodiment provides a method for evaluating the aeration performance of an oxygen-containing gas and aqueous solution mixing device. The gas source used is air (oxygen volume percentage is 21%), and the oxygen-containing gas and aqueous solution mixing device used is a micro-nano bubble aerator (model HIPROZ-10). The specific evaluation method is as follows:

[0121] 1) Install the device to be tested and the test water tank. The detection method adopts the non-steady-state measurement method, and the water in the water tank circulates through the circulation pump of the device to be tested.

[0122] 2) The liquid flow rate of the circulation pump is 8500L / h, the design circulation frequency is selected as 8.5, and the volume of the test water is 1000L.

[0123] 3) Pour 1000L of clean water into the water tank and record the clean water temperature, TDS and initial DO value.

[0124] 4) Add the catalyst cobalt chloride hexahydrate and deoxidizer sodium sulfite into the water tank. Use industrial grade sodium sulfite (Na2SO3), which is dissolved in water and oxidized to sodium sulfate (Na2SO4). Take water through the water tank sampling port, dissolve the cobalt chloride hexahydrate, add it to the water tank, and then add sodium sulfite to make the DO value of the clean water lower than 0.5mg / L.

[0125] 5) Select five test points with liquid-gas ratios of 47.22, 28.33, 14.17, 9.44 and 7.08. Through the pump circulation volume and liquid-gas ratio, the set gas flow rates can be obtained as 180L / h (3L / min), 300L / h (5L / min), 600L / h (10L / min), 900L / h (15L / min) and 1200L / h (20L / min). Turn on the circulation pump for the experiment.

[0126] 6) The gas flow rate is adjusted according to step 5) to allow the micro-nano bubble aerator to perform aeration.

[0127] 7) Use a dissolved oxygen testing device to record the changes in dissolved oxygen over time.

[0128] 8) Record other data.

[0129] 9) Based on the obtained data, substitute it into the formula (1)-(10) shown in Example 1 to calculate the aeration performance parameter index K L a, SOTR, SOTE and SAE values. The results are shown in Table 2.

[0130] Table 2

[0131]

[0132] With the liquid-gas ratio in Table 2 as the horizontal axis and SOTE, SOTR, and SAE as the vertical axis, curve graphs are drawn respectively, such as Figure 4-Figure 6 As shown. Figure 4-Figure 6 It can be seen that for this aerator, when the gas source is air, the lower the liquid-gas ratio, the higher the SOTR standard oxygen mass transfer rate; the higher the liquid-gas ratio, the higher the SOTE standard oxygen mass transfer efficiency; the lower the liquid-gas ratio, the higher the SAE standard aeration efficiency.

[0133] Figure 6 It can be concluded that SAE (standard aeration efficiency) decreases with the increase of liquid-gas ratio. This is because under the condition of no gas source energy consumption, the energy consumption of the pump is constant, and the energy consumption of the aerator comes only from pumping. As the liquid-gas ratio increases, SOTR (standard oxygen mass transfer rate) slows down, and the mass of oxygen transferred to the water per unit time decreases. Because SAE is the mass of oxygen transferred to the water per unit of useful work consumed under test conditions, so under the condition of constant pumping, SAE decreases as SOTR decreases.

[0134] Example 3

[0135] This embodiment provides a method for evaluating the aeration performance of an oxygen-containing gas and aqueous solution mixing device, the gas source used is oxygen, the aerator used is a micro-nano bubble aerator (model HIPROZ-10), the oxygen comes from a molecular sieve oxygen generator, and other experimental conditions and parameters are consistent with those of Example 2. The specific evaluation method is as follows:

[0136] 1) Install the device to be tested and the test water tank. The detection method adopts the non-steady-state measurement method, and the water in the water tank circulates through the circulation pump of the device to be tested.

[0137] 2) The liquid flow rate of the circulation pump is 8500L / h, the designed circulation frequency is 8.5, and the volume of water is determined to be 1000L.

[0138] 3) Pour 1000L of clean water into the water tank and record the clean water temperature, TDS and initial DO value.

[0139] 4) Add the catalyst cobalt chloride hexahydrate and deoxidizer sodium sulfite into the water tank. Use industrial grade sodium sulfite (Na2SO3), which is dissolved in water and oxidized to sodium sulfate (Na2SO4). Take water through the water tank sampling port, dissolve the cobalt chloride hexahydrate, add it to the water tank, and then add sodium sulfite to make the DO value of the clean water lower than 0.5mg / L.

[0140] 5) Select five test points with liquid-gas ratios of 47.22, 28.33, 14.17, 9.44 and 7.08. Through the pump circulation volume and liquid-gas ratio, the set gas flow rates can be obtained as 180L / h (3L / min), 300L / h (5L / min), 600L / h (10L / min), 900L / h (15L / min) and 1200L / h (20L / min). Turn on the circulation pump for the experiment.

[0141] 6) The gas flow rate is adjusted according to step 5) to allow the micro-nano bubble aerator to perform aeration.

[0142] 7) Use a dissolved oxygen testing device to record the changes in dissolved oxygen over time.

[0143] 8) Record other data.

[0144] 9) Based on the obtained data, substitute it into the formula (1)-(10) shown in Example 1 to calculate the aeration performance parameter index K L a, SOTR, SOTE and SAE values. The results are shown in Table 3 (wherein the oxygen concentration is volume percentage).

[0145] Table 3

[0146]

[0147] With the liquid-gas ratio in Table 3 as the horizontal axis and SOTE, SOTR, and SAE as the vertical axis, curve graphs are drawn respectively, such as Figure 7-Figure 9 As shown. Figure 7-Figure 9 It can be seen that for this aerator, when the gas source is oxygen, under the conditions of the five selected liquid-gas ratios, the lower the liquid-gas ratio, the higher the SOTR standard oxygen mass transfer rate; the higher the liquid-gas ratio, the higher the SOTE standard oxygen mass transfer efficiency; when the liquid-gas ratio is between 9.44 and 14.77, SAE peaks, with the best standard aeration efficiency. This is because when the gas source is oxygen, the oxygen generator consumes energy. As the liquid-gas ratio decreases, the gas flow rate also increases accordingly, and the energy consumption of oxygen production increases. SOTR increases as the liquid-gas ratio decreases. At this time, energy consumption and SOTR jointly affect the results of SAE.

[0148] In actual situations, when the SAE values ​​are close, we can compare other parameters to evaluate the aerator. For example, if we want to pursue the oxygen mass transfer rate while ensuring economic benefits, we can choose aeration when the liquid-to-gas ratio is 9.44. If we are more concerned about the oxygen utilization rate, we can choose aeration when the liquid-to-gas ratio is 14.17.

[0149] Example 4

[0150] This embodiment provides an evaluation method for the aeration performance of an oxygen-containing gas and aqueous solution mixing device. The gas source used is air (oxygen volume percentage is 21%), and the oxygen-containing gas and aqueous solution mixing device used is a micro-nano bubble aerator (model HIPROZ-3). The specific evaluation method is as follows:

[0151] 1) Install the device to be tested and the test water tank. The detection method adopts the non-steady-state measurement method, and the water in the water tank circulates through the circulation pump of the device to be tested.

[0152] 2) The liquid flow rate of the circulation pump is 2820L / h, the designed circulation frequency is 2.82, and the volume of water is 1000L.

[0153] 3) Pour 1000L of clean water into the water tank and record the clean water temperature, TDS and initial DO value.

[0154] 4) Add the catalyst cobalt chloride hexahydrate and deoxidizer sodium sulfite into the water tank. Use industrial grade sodium sulfite (Na2SO3), which is dissolved in water and oxidized to sodium sulfate (Na2SO4). Take water through the water tank sampling port, dissolve the cobalt chloride hexahydrate, add it to the water tank, and then add sodium sulfite to make the DO value of the clean water lower than 0.5mg / L.

[0155] 5) Select five test points with liquid-to-gas ratios of 47.00, 23.50, 15.67, 11.75 and 9.40. Through the pump circulation volume and liquid-to-gas ratio, the set gas flow rates can be obtained as 60 L / h (1 L / min), 120 L / h (2 L / min), 180 L / h (3 L / min), 240 L / h (4 L / min) and 300 L / h (3 L / min). Turn on the circulation pump for the experiment.

[0156] 6) The gas flow rate is adjusted according to step 5) to allow the micro-nano bubble aerator to perform aeration.

[0157] 7) Use a dissolved oxygen testing device to record the changes in dissolved oxygen over time.

[0158] 8) Record other data.

[0159] 9) Based on the obtained data, substitute it into the formula (1)-(10) shown in Example 1 to calculate the aeration performance parameter index K L a, SOTR, SOTE and SAE values. The results are shown in Table 4.

[0160] Table 4

[0161]

[0162] With the liquid-gas ratio in Table 4 as the abscissa and SOTE, SOTR, and SAE as the ordinates, curve graphs are drawn respectively, such as Figure 10-12 As shown. Figure 10-12 It can be seen that when the gas source is air, the lower the liquid-gas ratio, the higher the SOTR standard oxygen mass transfer rate; the higher the liquid-gas ratio, the higher the SOTE standard oxygen mass transfer efficiency; the lower the liquid-gas ratio, the higher the aeration effect of the SAE equipment.

[0163] Since Example 2 and Example 4 are the same series of self-priming jet aerators, only the pump circulation volume is different, it can be concluded that Figure 13-15 From Figure 13-Figure 15 It can be seen that the standard aeration efficiency of the two devices is very close, but the SOTR of the HIPROZ-10 device is obviously higher than that of the HIPROZ-3 device. This is because under the same liquid-gas ratio, the air intake of the HIPROZ-10 device is higher than that of the HIPROZ-3 device, so the SOTR standard oxygen mass transfer rate is higher. It can also be shown that the SAE standard aeration efficiency of this series of equipment is relatively uniform.

[0164] Example 5

[0165] This embodiment provides an evaluation method for the aeration performance of an oxygen-containing gas and aqueous solution mixing device. The gas source used is air (oxygen volume percentage is 21%), and the oxygen-containing gas and aqueous solution mixing device used is a nano bubble aerator (model OXYDEEP-0.3). The specific evaluation method is as follows:

[0166] 1) Install the device to be tested and the test water tank. The detection method adopts the non-steady-state measurement method, and the water in the water tank circulates through the circulation pump of the device to be tested.

[0167] 2) The liquid flow rate of the circulation pump is 240L / h, the designed circulation frequency is 8, and the volume of water is 30L.

[0168] 3) Pour 30L of clean water into the water tank and record the clean water temperature, TDS and initial DO value.

[0169] 4) Add the catalyst cobalt chloride hexahydrate and deoxidizer sodium sulfite into the water tank. Use industrial grade sodium sulfite (Na2SO3), which is dissolved in water and oxidized to sodium sulfate (Na2SO4). Take water through the water tank sampling port, dissolve the cobalt chloride hexahydrate, add it to the water tank, and then add sodium sulfite to make the DO value of the clean water lower than 0.5mg / L.

[0170] 5) Select four test points with liquid-to-gas ratios of 40.00, 20.00, 13.33 and 10.00. Through the pump circulation volume and liquid-to-gas ratio, the set air intake volumes can be obtained as 6L / h (0.1L / min), 12L / h (0.2L / min), 18L / h (0.3L / min) and 24L / h (0.4L / min). Turn on the circulation pump for the experiment.

[0171] 6) The gas flow rates in step 5) are adjusted respectively to allow the nano bubble aerator to perform aeration.

[0172] 7) Use a dissolved oxygen testing device to record the changes in dissolved oxygen over time.

[0173] 8) Record other data.

[0174] 9) Based on the obtained data, substitute it into the formula (1)-(10) shown in Example 1 to calculate the aeration performance parameter index K L a s , SOTR, SOTE and SAE values. The results are shown in Table 5.

[0175] Table 5

[0176]

[0177] With the liquid-gas ratio in Table 5 as the horizontal axis and SOTE, SOTR, and SAE as the vertical axis, curve graphs are drawn respectively, such as Figure 16-18 As shown. Figure 16-18 It can be seen that when the gas source is air, the lower the liquid-gas ratio, the higher the SOTR standard oxygen mass transfer rate; the higher the liquid-gas ratio, the higher the SOTE standard oxygen mass transfer efficiency; the lower the liquid-gas ratio, the higher the SAE standard aeration efficiency.

[0178] The cycle frequencies of Example 2 and Example 5 are very close, and the self-priming aerators used belong to two series. The evaluation method proposed in this patent can be used to compare and evaluate the two aerators. Figure 19-21 The comparison chart shown. Figure 4-Figure 6 It can be seen that under the test point conditions, the SOTE of the OXYDEEP-0.3 device is higher than the SOTE standard oxygen mass transfer efficiency of the HIPROZ-10 device, but the oxygen mass transfer rate of the OXYDEEP-0.3 device is significantly lower than that of the HIPROZ-10 device. This is because the gas flow rate of the OXYDEEP-0.3 device is lower under the same liquid-gas ratio conditions, and the oxygen dissolution rate is slower. Compared with SAE, after considering the energy consumption issue, the SAE standard aeration efficiency of the OXYDEEP-0.3 device is much lower than that of the HIPROZ-10 device. Under the same energy consumption, the HIPROZ-10 device transfers more oxygen mass to the water, so under normal circumstances, the HIPROZ-10 device is better than the OXYDEEP-0.3 device.

[0179] It should be noted that the evaluation method of the present invention is not only applicable to the nanobubble and micro-nano bubble aerators listed in the above embodiments, but also applicable to other jet aerators, and to other devices with gas-liquid mixing functions, such as gas-liquid mixing pumps, venturi tubes, membrane aeration, micro-nano bubble equipment, etc. These are not listed one by one in the present invention.

[0180] The method of the present invention can also be used to evaluate the aeration performance of oxygen-containing gases with different oxygen contents as gas sources, which are not limited to the air and oxygen with a volume percentage of more than 90 vol% listed in the above embodiments.

[0181] The above description of the embodiments is to facilitate those of ordinary skill in the art to understand and apply the present application. It is obvious that those familiar with the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without having to pay creative labor. Therefore, the present application is not limited to the embodiments herein, and improvements and modifications made by those skilled in the art based on the contents disclosed in the present application without departing from the scope and spirit of the present application are within the scope of the present application.

Claims

1. A method for evaluating the aeration performance of an oxygen-containing gas and aqueous solution mixing device, characterized in that: The following steps are involved: S1. Determine the oxygen content in the input oxygen-containing gas: S2. Determine the circulation pump flow rate of the device to be tested; S3. Determine the cycle frequency of a single test experiment of the device to be evaluated, and obtain the volume of the aqueous solution under the test conditions according to the circulation pump flow rate and the circulation frequency; the circulation frequency is the ratio of the circulation pump flow rate of the device to be tested to the volume of the aqueous solution under the test conditions; S4. Turn on the device to be tested to circulate the aqueous solution in the test container, add an oxygen scavenger so that the dissolved oxygen in the aqueous solution is less than 0.5 mg / L and stabilized, and then adjust the gas flow rate to input oxygen-containing gas into the aqueous solution; S5. Record dissolved oxygen and corresponding time values; S6. Repeat steps S1-S5 to obtain dissolved oxygen values ​​that vary over time at different circulation frequencies and different liquid-gas ratios; the liquid-gas ratio is the ratio of the circulation pump flow rate to the oxygen-containing gas flow rate; S7. Calculate the series of aeration performance parameters of the oxygen-containing gas and aqueous solution mixing device under different cycle frequencies and different liquid-gas ratios according to the dissolved oxygen value; and draw a graph or table of each aeration performance parameter with the liquid-gas ratio as the abscissa and the aeration performance parameter as the ordinate; the aeration performance parameters include K L a. At least one of SOTR, SOTE, SAE; The K L a is the oxygen mass transfer coefficient; SOTR is the standard oxygen mass transfer rate; SOTE is the standard oxygen mass transfer efficiency; SAE is the standard aeration efficiency.

2. The aeration performance evaluation method of the oxygen-containing gas and aqueous solution mixing device according to claim 1, characterized in that: In step S1, the oxygen content is any one of volume percentage, mole percentage or mass percentage; In step S3, the aqueous solution is any one of pure water, clean water, and tap water, and its water quality index TDS should be less than 2000 mg / L.

3. The aeration performance evaluation method of the oxygen-containing gas and aqueous solution mixing device according to claim 1, characterized in that: In step S3, the cycle frequency is 0.01-100.

4. The aeration performance evaluation method of the oxygen-containing gas and aqueous solution mixing device according to claim 1, characterized in that: The oxygen-containing gas and aqueous solution mixing device is a device with a gas-liquid mixing function, including any one of a jet aerator, a gas-liquid mixing pump, a venturi tube, a membrane aeration, and a micro-nano bubble device.

5. The aeration performance evaluation method of the oxygen-containing gas and aqueous solution mixing device according to claim 1, characterized in that: In step S7, K is calculated according to the following formulas (1)-(10): L a. SOTR, SOTE, SAE: In formula (1), C is the dissolved oxygen concentration in water corresponding to aeration time t, mg / L; t is time, min; C0 is the dissolved oxygen concentration corresponding to time 0, mg / L; is the dissolved oxygen concentration value when reaching steady state, mg / L; K L a is the oxygen mass transfer coefficient, 1 / min; K L a s =K L a×θ 20-T (3) In formulas (2)-(6), SOTR is the standard oxygen mass transfer rate, kg / h; K L a s is the total oxygen mass transfer coefficient under standard state and test conditions, 1 / min; is the saturated dissolved oxygen concentration value of the test point under standard conditions, mg / L; V is the volume of the aqueous solution in the test container, m 3 ; θ is the empirical coefficient of temperature correction, which is 1.024; T is the average water temperature during the test, ℃; is the dissolved oxygen concentration value when reaching steady state, mg / L; τ is the temperature correction coefficient; Ω is the pressure correction factor; It is the saturated dissolved oxygen concentration value at 101.235 kPa atmospheric pressure and test water temperature, mg / L; is the saturated dissolved oxygen concentration value under standard conditions, mg / L; P b is the absolute pressure of the gas during the test, kPa; P b0 101.235 kPa; In formulas (7)-(8), SOTE is the standard oxygen mass transfer efficiency, %; Wo2 is the mass flow rate of oxygen in the oxygen-containing gas, kg / h; ρ is the density of the oxygen-containing gas at the test temperature, kg / m 3 ;Q b is the actual flow rate of oxygen-containing gas, m 3 / h; Vol% (oxygen) is the mass percentage of oxygen in the gas; P=P1+P2 (10) In formulas (9)-(10), SAE is the standard aeration efficiency, kg / (kW·h); P is the total power required by the device to be tested, KW; P1 is the actual power required for the circulation of the aqueous solution, KW; P2 is the sum of the power converted from the preparation cost of the oxygen-containing gas and the actual power required for the process of entering the device, KW.

6. A method for evaluating the aeration performance of multiple oxygen-containing gas and aqueous solution mixing devices, characterized in that: The following steps are involved: A1. According to the method of steps S1-S7 in claim 1, a series of aeration performance parameters of multiple oxygen-containing gas and aqueous solution mixing devices at multiple cycle frequencies and different liquid-gas ratios are obtained; A2. Select a series of aeration performance parameters of multiple oxygen-containing gas and aqueous solution mixing devices at different liquid-to-gas ratios under a certain cycle frequency, draw a graph or table with a single aeration performance parameter as the ordinate and the liquid-to-gas ratio as the abscissa, and obtain comparative characteristics of multiple oxygen-containing gas and aqueous solution mixing devices under a single or multiple aeration performance parameters.

7. The method for evaluating the aeration performance of a plurality of oxygen-containing gas and aqueous solution mixing devices according to claim 6, characterized in that: The multiple oxygen-containing gas and aqueous solution mixing devices are devices with different pump circulation volumes and / or different gas flow rates; Each of the oxygen-containing gas and aqueous solution mixing devices is a device with a gas-liquid mixing function, including any one of a jet aerator, a gas-liquid mixing pump, a venturi tube, a membrane aeration, and a micro-nano bubble device.

8. The method for evaluating the aeration performance of multiple oxygen-containing gas and aqueous solution mixing devices according to claim 6, characterized in that: In step A1, the cycle frequency is 0.01-100; the liquid-gas ratio is 0.2-200.

9. An application of the evaluation method according to any one of claims 1 to 5 in designing a system based on a device for mixing oxygen-containing gas and aqueous solution, characterized in that: The application fields of the system include at least one of aquaculture, rice planting, lake and river oxygenation, ozone advanced oxidation, domestic sewage treatment, petrochemical sewage treatment, and supercritical fluid.

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