Accurate dosing device for acid-base regulation before reverse osmosis and control method thereof

Abstract

The invention provides a pre-reverse osmosis acid-base adjustment accurate dosing device and a control method thereof.The pre-reverse osmosis acid-base adjustment accurate dosing device comprises a water inlet flow meter, a water inlet pH meter, a water outlet pH meter, an acid-base dosing port, a mixer and a programmable controller, and the water inlet flow meter, the water inlet pH meter and the water outlet pH meter are all connected with the programmable controller; the acid-base dosing port is connected with the mixer, the water inlet flow meter, the water inlet pH meter and the water outlet pH meter output analog quantity signals to the programmable controller, and the programmable controller outputs analog quantity signals to a frequency converter of the acid-base dosing pump. The PH values measured by the inlet water PH meter and the outlet water PH meter are compared with the target PH value preset in the programmable controller for calculation, the running state and frequency value command of the acid-base dosing pump is fed back, the outlet water PH value is controlled to be closer to the target PH value, accurate adjustment of the PH value is achieved through the real-time monitoring and closed-loop feedback control technology, the running efficiency of a reverse osmosis membrane is improved, the service life of the reverse osmosis membrane is prolonged, and the energy consumption is reduced. The dosage is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of reverse osmosis water treatment, and in particular to a precise dosing device for acid-base regulation before reverse osmosis and a control method thereof. Background Art

[0002] In reverse osmosis water treatment, the pH of the influent significantly impacts the efficiency and lifespan of the membrane. Excessively high or low pH values ​​can degrade the performance of the reverse osmosis membrane and even damage the membrane assembly. Traditional methods of dosing acid and alkali solutions often rely on manual control or quantitative dosing, which not only wastes reagents but also lacks precise adjustment, failing to meet practical application requirements. Therefore, a device capable of real-time monitoring and precise pH adjustment is needed to ensure efficient operation of the reverse osmosis system. Summary of the Invention

[0003] The purpose of the present invention is to provide a precise dosing device for acid and alkali regulation before reverse osmosis and its control method, which can automatically adjust the acid and alkali dosing amount by real-time monitoring of the inlet pH value, outlet pH value and target pH value, and combine the flow signal of the flow meter to accurately control the operating state of the reverse osmosis membrane.

[0004] According to one object of the present invention, the present invention provides a precise dosing device for acid and alkali adjustment before reverse osmosis, comprising an inlet flow meter, an inlet pH meter, an outlet pH meter, an acid and alkali dosing port, a mixer and a programmable controller, wherein the inlet flow meter, the inlet pH meter and the outlet pH meter are all connected to the programmable controller, the acid and alkali dosing port is connected to the mixer, the inlet flow meter, the inlet pH meter and the outlet pH meter output analog signals to the programmable controller, and the programmable controller outputs analog signals to the frequency converter of the acid and alkali dosing pump.

[0005] Furthermore, the interior of the mixer is filled with SV type static pipeline mixer filler.

[0006] Furthermore, the total length of the mixer is 9 times its diameter.

[0007] Furthermore, the diameter of the middle reaction zone of the mixer is twice the diameter of the inlet and outlet pipes.

[0008] Furthermore, the acid and alkali dosing ports are separated to add acid and alkali agents respectively.

[0009] According to another object of the present invention, the present invention provides a control method for the above-mentioned acid-base adjustment and precise dosing device before reverse osmosis, comprising the following steps:

[0010] S1: Input the target pH value PH2 in the human-computer interaction interface of the programmable controller;

[0011] S2: The programmable controller reads the pH1 measured by the inlet water pH meter and compares it with the pH2;

[0012] S3: Calculate the molar concentrations QH and QOH of added acid and base in six cases according to the different relationships among pH1, pH2 and pH median;

[0013] S4: Preset the dosing pump operating frequency required for different QH and QOH according to the acid and alkali type, reagent concentration, pump parameters and water inlet flow information;

[0014] S5: The programmable controller reads the pH3 measured by the outlet water pH meter and compares it with the pH2;

[0015] S6: According to the different relationship between PH1 and PH2, the operating frequency of the dosing pump is modified;

[0016] S7: The programmable controller outputs frequency commands to the frequency converter to control the operation of the acid and alkali dosing pump.

[0017] Furthermore, the calculation formula in step S3 includes:

[0018] (1) PH2<7 and PH1<7 and PH1-PH2<0

[0019] Then QH=0, QOH=(10^-PH1)-(10^-PH2);

[0020] (2) PH2<7 and PH1<7 and PH1-PH2>0

[0021] Then QH=(10^-PH2)-(10^-PH1), QH=0;

[0022] (3) PH2<7 and PH1>7

[0023] Then QH=[10^(PH1-14)]+(10^-PH2)-(10^-7), QOH=0;

[0024] (4) PH2>7 and PH1<7

[0025] Then QH=0, QOH=[10^(PH1-14)]+[10^(PH2-14)]-(10^-7);

[0026] (5) PH2>7 and PH1>7 and PH1-PH2<0

[0027] Then QH=0, QOH=[10^(PH2-14)]-[10^(PH1-14)];

[0028] (6) PH2>7 and PH1>7 and PH1-PH2>0

[0029] Then QH=[10^(PH1-14)]-[10^(PH1-14)], QOH=0.

[0030] Furthermore, the correction in step S6 includes adjusting the operating frequency of the acid dosing pump or the alkali dosing pump according to the difference between the pH values ​​of the inlet water and the outlet water and the target pH value.

[0031] Furthermore, in step S6, FH and FOH are corrected in eight types and run in a loop:

[0032] (1) In step S3, for types (2), (3) and (6):

[0033] ①PH3-PH2<0 and PH2-PH3<1, then FH=FH-1;

[0034] ②PH3-PH2<0 and PH2-PH3>1, then FH=FH-3;

[0035] ③PH3-PH2>0 and PH3-PH2<1, then FH=FH+1;

[0036] ④PH3-PH2>0 and PH3-PH2>1, then FH=FH+3;

[0037] (2) In step S3, for types (1), (4) and (5):

[0038] ⑤PH3-PH2<0 and PH2-PH3<1, then FOH=FOH+1;

[0039] ⑥PH3-PH2<0 and PH2-PH3>1, then FOH=FOH+3;

[0040] ⑦PH3-PH2>0 and PH2-PH3<1, then FOH=FOH-1;

[0041] ⑧PH3-PH2>0 and PH2-PH3>1, then FOH=FOH-3.

[0042] Furthermore, in step S7, the operating frequency of the dosing pump is adjusted by controlling the frequency converter, thereby accurately controlling the dosing amount.

[0043] The technical solution of the present invention compares and calculates the pH values ​​measured by the inlet pH meter and the outlet pH meter with the target pH value preset in the programmable controller, and feeds back the operating status and frequency value command of the acid and alkali dosing pump to control the outlet pH value to be closer to the target pH value. Real-time monitoring and closed-loop feedback control technology are used to achieve precise adjustment of the pH value, thereby improving the operating efficiency and life of the reverse osmosis membrane and reducing the dosage. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0045] Figure 1 Schematic diagram of the structure of an embodiment of the present invention;

[0046] Figure 2 A control logic diagram of a programmable controller according to an embodiment of the present invention;

[0047] In the figure, 1. Water inlet flow meter; 2. Water inlet pH meter; 3. Water outlet pH meter; 4. Acid and alkali dosing port; 5. Mixer; 6. Programmable controller. DETAILED DESCRIPTION

[0048] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0049] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore should not be understood as limiting the present invention.

[0050] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a communication between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0051] Example 1

[0052] like Figure 1 As shown, a device for precise dosing of acid and alkali adjustment before reverse osmosis includes an inlet flow meter 1, an inlet pH meter 2, an outlet pH meter 3, an acid and alkali dosing port 4, a mixer 5, and a programmable controller 6. The device automatically calculates and adjusts the operating frequency of the dosing pump by combining the flow signal measured by the inlet flow meter 1 with the pH value information of the inlet pH meter 2 and the outlet pH meter 3, in combination with the target pH value set in the programmable controller 6, thereby achieving precise dosing and ensuring the optimal operating state of the reverse osmosis system. Among them:

[0053] The water inlet flow meter 1 is connected to the mixer 5 , the water inlet pH meter 2 and the acid and alkali dosing port 4 are connected to the water inlet side of the mixer 5 , and the water outlet pH meter 3 is connected to the water outlet side of the mixer 5 .

[0054] The water inlet flow meter 1, the water inlet pH meter 2, and the water outlet pH meter 3 are all connected to the programmable controller 6, the acid and alkali dosing port 4 is connected to the mixer 5, the water inlet flow meter 1, the water inlet pH meter 2, and the water outlet pH meter 3 output analog signals to the programmable controller 6, and the programmable controller 6 outputs analog signals to the frequency converter of the acid and alkali dosing pump.

[0055] The water inlet flowmeter 1 is used to measure the water inlet flow rate. The water enters through the water inlet end of the flowmeter 1, measures the water inlet flow rate, and transmits the data to the programmable controller 6 to control the operation of the dosing pump.

[0056] The inlet pH meter 2 and the outlet pH meter 3 are used to measure the pH values ​​of the inlet water and the outlet water respectively, and transmit the measured values ​​to the programmable controller 6 for analysis and processing.

[0057] Specifically, the metered incoming water enters the mixer 5, the pH value is measured by the inlet pH meter 2 at the water inlet end of the mixer 5, and the measurement data is transmitted to the programmable controller 6; after the incoming water and the reagent are fully mixed and reacted in the mixer 5, the pH value is measured by the outlet pH meter 3 at the water outlet end of the mixer 5, and the measurement data is transmitted to the programmable controller 6.

[0058] The acid and alkali dosing port 4 is used to inject acid or alkali, which is mixed with the incoming water to adjust the pH. The acid and alkali dosing ports 4 are separate, allowing the acid and alkali to be added separately. The water is then mixed with the acid or alkali injected through the acid and alkali dosing port 4 at the water inlet of the mixer 5.

[0059] Mixer 5 is filled with SV-type static pipeline mixer packing, which ensures thorough mixing of the acid and base reagents with the incoming water. The total length of mixer 5 is nine times its diameter. The diameter of the central reaction zone of mixer 5 is twice the diameter of the inlet and outlet pipes.

[0060] After the incoming water and the reagent are mixed, they enter the mixer 5 together. In order to fully mix and react the incoming water and the reagent, the mixer 5 is equipped with an SV type static pipeline mixer filler. Relying on the internal fixed corrugated structure, the fluid produces cutting, rotation and turbulence when flowing through, thereby achieving full mixing and reaction of the incoming water and the reagent. The designed residence time of the incoming water and the reagent in the mixer 5 is 2.4s.

[0061] The programmable controller 6 receives data from various sensors, calculates the operating frequency of the dosing pump, and displays relevant information through the human-computer interaction interface.

[0062] The control logic of the present invention:

[0063] The control logic of programmable controller 6 includes variables such as inlet flow rate Q, inlet pH value PH1, target pH value PH2, outlet pH value PH3, target molar concentration of acid addition QH, target molar concentration of alkali addition QOH, set operating frequency FH ​​for the acid dosing pump, and set operating frequency FOH for the alkali dosing pump. Based on the target pH value input from the human-machine interface, as well as the inlet flow rate Q measured by flowmeter 1, the measured value PH1 of inlet pH meter 2, and the measured value PH1 of outlet pH meter 3, programmable controller 6 performs internal calculations to output the set operating frequency FH ​​and FOH for the acid or alkali dosing pump.

[0064] The programmable controller 6 achieves precise acid and alkali dosing control through the following steps:

[0065] Enter the target pH value PH2 in the human-computer interaction interface;

[0066] Read the pH1 measured by the inlet pH meter 2 and compare it with the target pH2;

[0067] According to the different relationships among pH1, pH2 and pH median, the molar concentrations QH and QOH of added acid and base are calculated in six cases;

[0068] According to information such as acid and alkali type, reagent concentration, pump parameters and water inlet flow, the dosing pump operating frequency corresponding to different QH and QOH is preset;

[0069] Read the pH3 measured by the outlet pH meter 3 and compare it with the target pH2 to further correct the frequency of the dosing pump.

[0070] This system compares the pH values ​​measured by inlet and outlet pH meters with the target pH value preset in a programmable controller, and provides feedback on the operating status and frequency command of the acid and alkali dosing pump. This system uses real-time monitoring and closed-loop feedback control technology and algorithms to effectively achieve precise pH adjustment, improve the operating efficiency and lifespan of the reverse osmosis membrane, and reduce the dosage. It is particularly suitable for acid-base adjustment and precise dosing control of wastewater before reverse osmosis.

[0071] Example 2

[0072] The working process of the present invention is as follows:

[0073] The water enters through the water inlet port of the flow meter 1, the water flow is measured, and the measured flow data is transmitted to the programmable controller 6;

[0074] The metered water enters the mixer 5, and the pH value is measured by the water pH meter 2 at the water inlet of the mixer 5, and the measured data is transmitted to the programmable controller 6;

[0075] Mixing at the water inlet end of the mixer 5 with the acid or alkali agent injected through the acid and alkali dosing port 4;

[0076] After the water and the reagent are mixed, they enter the mixer 5 together. To ensure that the water and the reagent are fully mixed and reacted, the mixer 5 is equipped with an SV type static pipeline mixer filler. The internal fixed corrugated structure causes cutting, rotation and turbulence when the fluid flows through, achieving full mixing and reaction of the water and the reagent. The designed residence time of the water and the reagent in the mixer 5 is 2.4s.

[0077] After the influent water and the reagent are fully mixed and reacted in the mixer 5, the pH value is measured by the outlet pH meter 3 at the outlet of the mixer 5, and the measured data is transmitted to the programmable controller 6;

[0078] The programmable controller 6 uses the target pH value input through the human-machine interface and the input signals of the inlet flow Q measured by the flow meter 1, the measured value PH1 of the inlet pH meter 2, and the measured value PH1 of the outlet pH meter 3 to output the given operating frequency values ​​FH and FOH of the acid or alkali dosing pump through internal calculation;

[0079] The water after adjusting the pH value to the appropriate level enters the next reverse osmosis treatment unit.

[0080] The present invention compares and calculates the pH values ​​measured by the inlet pH meter and the outlet pH meter with the target pH value preset in the programmable controller, and feeds back the operating status and frequency value command of the acid and alkali dosing pump to control the outlet pH value to be closer to the target pH value. Real-time monitoring and closed-loop feedback control technology are used to achieve precise regulation of the pH value, thereby improving the operating efficiency and service life of the reverse osmosis membrane and reducing the dosage. At the same time, the present invention adopts a pipeline form with a reasonable appearance, and controls the dosage by controlling the frequency of the dosing pump. Without changing the original dosing system, the reverse osmosis system can be quickly modified.

[0081] Example 3

[0082] like Figure 2 As shown, the control method of the above-mentioned acid-base adjustment and precise dosing device before reverse osmosis includes the following steps:

[0083] S1: Input the target pH value PH2 in the human-computer interaction interface of the programmable controller 6;

[0084] S2: The programmable controller 6 reads the pH1 measured by the inlet pH meter 2 and compares it with the pH2;

[0085] S3: According to the different relationships among pH1, pH2 and pH median value 7, the molar concentrations QH and QOH of acid and alkali are calculated in six cases and circulated;

[0086] S4: Preset the dosing pump operating frequency required for different QH and QOH according to information such as acid and alkali type, reagent concentration, dosing pump parameters and water inlet flow rate;

[0087] S5: The programmable controller reads the pH3 measured by the outlet water pH meter and compares it with the pH2;

[0088] S6: According to the different relationship between PH1 and PH2, the operating frequency of the dosing pump is modified;

[0089] S7: The programmable controller outputs frequency commands to the frequency converter to control the operation of the acid and alkali dosing pump.

[0090] The calculation formula in step S3 includes six types:

[0091] (1) PH2<7 and PH1<7 and PH1-PH2<0

[0092] Then QH=0, QOH=(10^-PH1)-(10^-PH2);

[0093] (2) PH2<7 and PH1<7 and PH1-PH2>0

[0094] Then QH=(10^-PH2)-(10^-PH1), QH=0;

[0095] (3) PH2<7 and PH1>7

[0096] Then QH=[10^(PH1-14)]+(10^-PH2)-(10^-7), QOH=0;

[0097] (4) PH2>7 and PH1<7

[0098] Then QH=0, QOH=[10^(PH1-14)]+[10^(PH2-14)]-(10^-7);

[0099] (5) PH2>7 and PH1>7 and PH1-PH2<0

[0100] Then QH=0, QOH=[10^(PH2-14)]-[10^(PH1-14)];

[0101] (6) PH2>7 and PH1>7 and PH1-PH2>0

[0102] Then QH=[10^(PH1-14)]-[10^(PH1-14)], QOH=0.

[0103] The correction in step S6 includes adjusting the operating frequency of the acid dosing pump or the alkali dosing pump according to the difference between the inlet and outlet pH values ​​and the target pH value. In step S6, the FH and FOH are corrected in eight types and run in a cycle:

[0104] (1) In step S3, for types (2), (3) and (6):

[0105] ①PH3-PH2<0 and PH2-PH3<1, then FH=FH-1;

[0106] ②PH3-PH2<0 and PH2-PH3>1, then FH=FH-3;

[0107] ③PH3-PH2>0 and PH3-PH2<1, then FH=FH+1;

[0108] ④PH3-PH2>0 and PH3-PH2>1, then FH=FH+3;

[0109] (2) In step S3, for types (1), (4) and (5):

[0110] ⑤PH3-PH2<0 and PH2-PH3<1, then FOH=FOH+1;

[0111] ⑥PH3-PH2<0 and PH2-PH3>1, then FOH=FOH+3;

[0112] ⑦PH3-PH2>0 and PH2-PH3<1, then FOH=FOH-1;

[0113] ⑧PH3-PH2>0 and PH2-PH3>1, then FOH=FOH-3.

[0114] In step S7, the operating frequency of the dosing pump is adjusted by controlling the frequency converter, thereby accurately controlling the dosing amount.

[0115] The programmable controller can adjust the pH value of the inlet and outlet water in real time through closed-loop feedback control, thereby improving the operating efficiency and life of the reverse osmosis membrane.

[0116] The present invention compares and calculates the pH values ​​measured by the inlet pH meter and the outlet pH meter with the target pH value preset in the programmable controller, and feeds back the operating status and frequency value command of the acid and alkali dosing pump to control the outlet pH value to be closer to the target pH value. Real-time monitoring and closed-loop feedback control technology are used to achieve precise regulation of the pH value, thereby improving the operating efficiency and service life of the reverse osmosis membrane and reducing the dosage.

[0117] The present invention compares the inlet pH value with the target pH value in various ways, iteratively calculates the given dosing pump operating frequency, and compares the outlet pH value with the target pH value in various ways, iteratively calculates and corrects the given dosing pump operating frequency, thereby achieving precise control of the dosing amount. The present invention adopts a pipeline form with a reasonable appearance, and controls the dosing amount by controlling the dosing pump frequency. Without changing the original dosing system, the present invention can quickly modify the reverse osmosis system.

[0118] The present invention provides a device for precise dosing of acid and alkalinity before reverse osmosis (RO) treatment, and its control method. It is particularly suitable for adjusting the pH and precisely controlling dosing of wastewater before it enters a RO treatment system. By monitoring the pH values ​​of the influent and effluent in real time and utilizing a closed-loop feedback mechanism between a programmable controller (PLC) and a dosing pump control system, the RO system's pH can be precisely adjusted, thereby optimizing the operating efficiency of the RO membrane and extending its service life.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A precise dosing device for acid and alkali adjustment before reverse osmosis, characterized in that: The invention comprises an inlet flow meter, an inlet pH meter, an outlet pH meter, an acid and alkali dosing port, a mixer and a programmable controller. The inlet flow meter, the inlet pH meter and the outlet pH meter are all connected to the programmable controller. The acid and alkali dosing port is connected to the mixer. The inlet flow meter, the inlet pH meter and the outlet pH meter output analog signals to the programmable controller. The programmable controller outputs analog signals to the frequency converter of the acid and alkali dosing pump.

2. The device for precise dosing of acid and alkali adjustment before reverse osmosis according to claim 1, characterized in that: The interior of the mixer is filled with SV type static pipeline mixer filler.

3. The device for precise dosing of acid and alkali adjustment before reverse osmosis according to claim 1, characterized in that: The total length of the mixer is 9 times its diameter.

4. The device for precise dosing of acid and alkali adjustment before reverse osmosis according to claim 1, characterized in that: The diameter of the middle reaction zone of the mixer is twice the diameter of the water inlet and outlet pipes.

5. The device for precise dosing of acid and alkali adjustment before reverse osmosis according to claim 1, characterized in that: The acid and alkali adding ports are separated and the acid and alkali agents are added respectively.

6. The control method of the device for precise dosing of acid and alkali regulation before reverse osmosis according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: Input the target pH value PH2 in the human-computer interaction interface of the programmable controller; S2: The programmable controller reads the pH1 measured by the inlet water pH meter and compares it with the pH2; S3: Calculate the molar concentrations QH and QOH of added acid and base in six cases according to the different relationships among pH1, pH2 and pH median; S4: Preset the dosing pump operating frequency required for different QH and QOH according to the acid and alkali type, reagent concentration, pump parameters and water inlet flow information; S5: The programmable controller reads the pH3 measured by the outlet water pH meter and compares it with the pH2; S6: According to the different relationship between PH1 and PH2, the operating frequency of the dosing pump is modified; S7: The programmable controller outputs frequency commands to the frequency converter to control the operation of the acid and alkali dosing pump.

7. The control method of the device for precise dosing of acid and alkali regulation before reverse osmosis according to claim 6, characterized in that: The calculation formula in step S3 includes: (1) PH2<7 and PH1<7 and PH1-PH2<0 Then QH=0, QOH=(10^-PH1)-(10^-PH2); (2) PH2<7 and PH1<7 and PH1-PH2>0 Then QH=(10^-PH2)-(10^-PH1), QH=0; (3) PH2<7 and PH1>7 Then QH=[10^(PH1-14)]+(10^-PH2)-(10^-7), QOH=0; (4) PH2>7 and PH1<7 Then QH=0, QOH=[10^(PH1-14)]+[10^(PH2-14)]-(10^-7); (5) PH2>7 and PH1>7 and PH1-PH2<0 Then QH=0, QOH=[10^(PH2-14)]-[10^(PH1-14)]; (6) PH2>7 and PH1>7 and PH1-PH2>0 Then QH=[10^(PH1-14)]-[10^(PH1-14)], QOH=0.

8. The control method of the device for precise dosing of acid and alkali adjustment before reverse osmosis according to claim 6, characterized in that: The correction in step S6 includes adjusting the operating frequency of the acid dosing pump or the alkali dosing pump according to the difference between the pH values ​​of the inlet water and the outlet water and the target pH value.

9. The control method of the device for precise dosing of acid and alkali adjustment before reverse osmosis according to claim 8, characterized in that: In step S6, FH and FOH are corrected in eight types and run in a loop: (1) In step S3, for types (2), (3) and (6): ①PH3-PH2<0 and PH2-PH3<1, then FH=FH-1; ②PH3-PH2<0 and PH2-PH3>1, then FH=FH-3; ③PH3-PH2>0 and PH3-PH2<1, then FH=FH+1; ④PH3-PH2>0 and PH3-PH2>1, then FH=FH+3; (2) In step S3, for types (1), (4) and (5): ⑤PH3-PH2<0 and PH2-PH3<1, then FOH=FOH+1; ⑥PH3-PH2<0 and PH2-PH3>1, then FOH=FOH+3; ⑦PH3-PH2>0 and PH2-PH3<1, then FOH=FOH-1; ⑧PH3-PH2>0 and PH2-PH3>1, then FOH=FOH-3.

10. The control method of the device for precise dosing of acid and alkali adjustment before reverse osmosis according to claim 6, characterized in that: In step S7, the operating frequency of the dosing pump is adjusted by controlling the frequency converter, thereby accurately controlling the dosing amount.

Images