A method and apparatus for accurate measurement of neutralization reaction ph

Abstract

The application discloses a kind of neutralization reaction pH value accurate measurement method and device.The method includes: acid in acid storage tank is pumped into pipeline mixer with directly sent waste lye and is mixed and reacts;Product 1# waste lye leaves pipeline mixer, wherein gas phase 1# acid gas enters upward degassing pipeline, liquid phase 2# waste lye enters downward liquid pipeline;2# waste lye is sent into degassing tank gas-liquid separation, separated 2# acid gas is mixed into downstream processing with 1# acid gas;Neutralized waste lye of gas-liquid separation is sent into stripping tank stripping, 3# acid gas obtained and waste lye after neutralization are sent into downstream processing respectively;The pH value of 2# waste lye is detected using the pH value detector arranged on the horizontal pipe of downward liquid pipeline, and the acid injection amount of acid pump into pipeline mixer is adjusted based on the pH value.The application has the advantages of simple process, stable operation, high detection accuracy, low operation energy consumption and cost, and sensitive adjustment.

Description

TECHNICAL FIELD

[0001] The present application relates to a pH measurement method, in particular to a neutralization reaction pH accurate measurement method and device, which can realize accurate pH measurement. BACKGROUND

[0002] Whether it is industrial production or industrial wastewater treatment, the measurement of pH value is usually encountered. The pH value in the chemical reaction process is directly related to the reaction performance, and is one of the key process conditions for determining whether the reaction can proceed smoothly. In the field of industrial wastewater treatment, for the neutralization treatment of acid and alkali wastewater, pH value is one of the most critical indicators for controlling the amount of chemicals added and showing whether the wastewater treatment meets the standards, therefore, it is particularly important to measure the pH value of the wastewater in a timely and accurate manner.

[0003] For industrial wastewater treatment, due to the variety of types, the wastewater treatment process and method are also different (such as continuous flow treatment method, intermittent treatment method), and the corresponding pH value measurement method is also different. Therefore, only by reasonably setting the measurement position and method of the pH meter according to different treatment methods and wastewater characteristics, can the measured pH value be true and effective, and the data can be used to reasonably add chemical agents and adjust process parameters for wastewater treatment.

[0004] For oil refining and ethylene waste lye, with the increase of high-sulfur crude oil processing capacity and the continuous increase of ethylene plant scale, the discharge of waste lye also increases. In the petrochemical production process, NaOH solution is often used to absorb H2S, alkali wash oil and cracking gas, resulting in waste lye containing a large amount of pollutants. How to treat waste lye has been a core problem of water pollution control for oil refineries and ethylene plants in China.

[0005] Waste lye has always been a strong corrosive chemical that can harm the human body and the environment if not properly treated. Common waste lye treatment methods include acid-base neutralization method, Micro-ELE catalytic oxidation technology, advanced oxidation technology, DTRO membrane concentration technology, and combined process method. The acid-base neutralization method is a common waste lye treatment method. Because the pH of waste lye is very high, it cannot be directly discharged, and acid / waste acid needs to be added to adjust the pH to neutral. After the H2S and CO2 gas released in the neutralization is stripped out, it is treated separately. This method first removes the grease in the waste lye, and then uses 98% concentrated sulfuric acid to acidify the ethylene waste lye to pH = 2-4, and then reacts in the neutralization tank. The sodium sulfide solution is converted into a sodium sulfate solution, which is sent to the sewage plant for biochemical treatment and discharge. The H2S and CO2 gas generated during neutralization is stripped out and sent to the flare for combustion.

[0006] The adding mode and adding amount of the acid / waste acid and the accuracy of pH measurement are closely related. In the aspect of pH measurement, the prior art has made certain technical improvements in the measurement mode, accuracy and timeliness, but the comprehensive performance needs to be further improved. A pH measurement method with high efficiency, high accuracy, low cost and low energy consumption is the development direction in the field. SUMMARY

[0007] The present application provides a method and device for accurately measuring the pH value of acid-base neutralization reaction with high efficiency, high accuracy, low cost and low energy consumption, which is particularly suitable for the neutralization reaction condition of waste lye in refining and chemical enterprises.

[0008] To achieve the above-mentioned purpose, the first aspect of the present application provides a method for accurately measuring the pH value of neutralization reaction, which comprises:

[0009] (1) The acid in the acid storage tank is sent into the pipeline mixer by the acid pump and mixed with the waste lye sent by the waste lye feeding pipeline to carry out neutralization reaction, obtaining 1# neutralized waste lye;

[0010] (2) The 1# neutralized waste lye exits the outlet pipeline of the pipeline mixer, wherein the gas phase 1# acidic gas enters the upward degassing pipeline, and the liquid phase 2# neutralized waste lye enters the downward liquid pipeline;

[0011] (3) The pH value of the 2# neutralized waste lye is detected by a pH detector, and the acid injection amount of the acid pump into the pipeline mixer is adjusted based on the pH value; the downward liquid pipeline comprises a vertical pipe and a horizontal pipe, and the pH detector is arranged on the horizontal pipe of the downward liquid pipeline;

[0012] (4) The 2# neutralized waste lye is sent into a degassing tank through the downward liquid pipeline to carry out gas-liquid separation, the obtained gas phase 2# acidic gas is discharged through the gas phase discharge pipeline of the degassing tank and mixed with the 1# acidic gas to be sent into a downstream acid gas treatment device, and the obtained liquid phase neutralized waste lye is sent into a stripping tank through the liquid phase discharge pipeline of the degassing tank to be stripped by stripping gas;

[0013] (5) The gas phase 3# acidic gas and the liquid phase neutralized waste lye obtained by stripping are sent into the downstream acid gas treatment device and the sewage treatment device through the gas phase discharge pipeline and the liquid phase discharge pipeline of the stripping tank, respectively.

[0014] The second aspect of the present application provides a device for accurately measuring the pH value of neutralization reaction, which comprises an acid storage tank, an acid pump, a pipeline mixer, a pH detector, a degassing tank and a stripping tank.

[0015] The discharge pipeline of the acid storage tank is connected to the acid pump and the pipeline mixer in sequence;

[0016] The pipeline mixer is provided with a waste lye feeding pipeline and a pipeline mixer outlet pipeline, the pipeline mixer outlet pipeline is divided into two branches, one is an upward degassing pipeline and the other is a downward liquid pipeline, the downward liquid pipeline is connected with a degassing tank feeding port, and the pH detector is arranged on the horizontal pipe of the downward liquid pipeline and forms a control loop with an acid pump.

[0017] The degassing tank is provided with a degassing tank gas phase discharge pipeline and a degassing tank liquid phase discharge pipeline, the degassing tank gas phase discharge pipeline is provided with a pressure control valve and is communicated with the upward degassing pipeline, and the pipeline communication point is located between the degassing tank and the pressure control valve.

[0018] The stripping tank is provided with a stripping tank feeding port, a stripping gas inlet, a stripping tank gas phase discharge pipeline and a stripping tank liquid phase discharge pipeline, and the stripping tank feeding port is connected with the degassing tank liquid phase discharge pipeline.

[0019] The beneficial effects of the present application are:

[0020] 1. The neutralization reaction pH accurate measurement method provided by the present application adopts the process scheme of pipeline mixer coarse adjustment and subsequent adjustment tank fine adjustment, avoids the influence of carbon dioxide gas generated by the neutralization reaction of waste lye and acid in the pipeline mixer on the plug flow of the medium in the pipeline and the vibration of the pipeline and the influence on the pH measurement accuracy, and the detection accuracy is ± 0.05 pH.

[0021] 2. The neutralization reaction pH accurate measurement method provided by the present application, the pipeline mixer outlet pipeline is divided into two branches, one is an upward degassing pipeline and the other is a downward liquid pipeline, the acidic gas (such as CO2) generated in the liquid phase is discharged through the upward degassing pipeline as much as possible, the content of the acidic gas in the liquid phase is reduced, and the pH measurement accuracy of the liquid phase is ensured.

[0022] 3. The neutralization reaction pH accurate measurement method provided by the present application is provided with an online pH detector on the downward liquid pipeline of the pipeline mixer outlet, the pH detector is arranged on the horizontal pipe, the detection point is not less than 10D (the diameter of the pipeline) away from the elbow of the vertically downward liquid pipeline, and the downward liquid pipeline is provided with a certain static liquid column height, so that the gas-liquid phase flow is stable and the acidic gas content in the liquid phase is low.

[0023] 4. Compared with the prior art, the neutralization reaction pH accurate measurement method provided by the present application has the advantages of stable operation, high detection accuracy, low operation energy consumption and cost, sensitive adjustment and the like by arranging the gas phase pipeline and the liquid phase pipeline.

[0024] Other features and advantages of the present application will be described in detail in the following specific embodiment part. Attached Figure Description

[0025] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.

[0026] Figure 1 This is a flowchart illustrating the first specific embodiment of the present invention.

[0027] Figure 2 This is a flowchart illustrating the second specific embodiment provided by the present invention.

[0028] Figure 3 This is a flowchart illustrating the third specific embodiment provided by the present invention.

[0029] Explanation of reference numerals in the attached figures:

[0030] 1- Waste alkali solution, 2- Neutralized waste alkali solution #1, 3- Acid, 4- Neutralized waste alkali solution #2, 5- Acid gas #1, 6- Acid gas #2, 7- Neutralized waste alkali solution #3, 8- Acid gas #3, 9- Neutralized waste alkali solution, 10- Stripping gas;

[0031] 101-Acid storage tank, 102-Acid pump, 103-Pipeline mixer, 104-Degassing tank, 105-Stripping tank. Detailed Implementation

[0032] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0033] In this disclosure, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in its normal operating state, while "inner" and "outer" refer to their positions relative to the device's outline. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0034] This invention provides a method for accurately measuring the pH value of a neutralization reaction, the method comprising:

[0035] (1) The acid 3 in the acid storage tank 101 is sent into the pipeline mixer 103 by the acid pump 102 to mix with the waste lye 1 fed by the waste lye feed pipeline and to carry out a neutralization reaction, so as to obtain the 1# neutralized waste lye 2;

[0036] (2) The 1# neutralized waste lye 2 exits the outlet pipeline of the pipeline mixer 103, wherein the gaseous phase 1# acid gas 5 enters the upward degassing pipeline, and the liquid phase 2# neutralized waste lye 4 enters the downward liquid pipeline;

[0037] (3) The pH value of the 2# neutralized waste lye 4 is detected by the pH detector, and the acid injection amount fed into the pipeline mixer 103 by the acid pump 102 is adjusted based on the pH value; the downward liquid pipeline includes a vertical pipe and a horizontal pipe, and the pH detector is arranged on the horizontal pipe of the downward liquid pipeline;

[0038] (4) The 2# neutralized waste lye 4 is sent into the degassing tank 104 by the downward liquid pipeline to carry out gas-liquid separation, the obtained gaseous phase 2# acid gas 6 is discharged through the gaseous phase discharge pipeline of the degassing tank and is mixed with the 1# acid gas 5 to be fed into the downstream acid gas treatment device; the obtained liquid phase neutralized waste lye 7 is sent into the stripping tank 105 through the liquid phase discharge pipeline of the degassing tank to be stripped by the stripping gas 10;

[0039] (5) The gaseous phase 3# acid gas 8 and the liquid phase neutralized waste lye 9 obtained by stripping are respectively sent into the downstream acid gas treatment device and the sewage treatment device through the gaseous phase discharge pipeline and the liquid phase discharge pipeline of the stripping tank.

[0040] Optionally, the waste lye 1 includes at least one of ethylene waste lye and oil refining waste lye; the acid 3 is selected from at least one of sulfuric acid, hydrochloric acid and nitric acid, and is preferably concentrated sulfuric acid.

[0041] The waste lye contains Na2S, NaSH and unreacted NaOH, Na2CO3, light hydrocarbon oil and the like. The sulfide reacts with the acid to generate sulfate and hydrogen sulfide, and the Na2CO3 reacts with the acid to generate sulfate and CO2, and the generated CO2 needs to be separated in time to improve the accuracy of the pH value. The pH value of the 1# neutralized waste lye 2 after neutralization is 1.8-6.2.

[0042] Optionally, the flow rate of the liquid phase 2# neutralized waste lye 4 is 0.1-1.5 m / s, and is preferably 0.3-0.8 m / s.

[0043] Optionally, the stripping gas is selected from at least one of low-pressure steam, nitrogen, air and oxygen, and is preferably low-pressure steam and / or air.

[0044] Specifically, the acid injection amount is adjusted by the rotation speed or stroke of the acid pump 102, and is preferably adjusted by the stroke of the acid pump 102.

[0045] The application also provides a neutralization reaction pH value accurate measuring device, characterized in that the pH value accurate measuring device comprises an acid storage tank 101, an acid pump 102, a pipeline mixer 103, a pH value detector, a degassing tank 104 and a stripping tank 105.

[0046] The discharge pipeline of the acid storage tank 101 is connected with the acid pump 102 and the pipeline mixer 103 in sequence.

[0047] The pipeline mixer 103 is provided with a waste lye feeding pipeline and a pipeline mixer outlet pipeline, the pipeline mixer outlet pipeline is divided into two branches, one branch is an upward degassing pipeline and the other branch is a downward liquid pipeline, the downward liquid pipeline is connected with a degassing tank feeding port, and the pH value detector is arranged on a horizontal pipe of the downward liquid pipeline and forms a control loop with the acid pump 102.

[0048] The degassing tank 104 is provided with a degassing tank gas phase discharge pipeline and a degassing tank liquid phase discharge pipeline, the degassing tank gas phase discharge pipeline is provided with a pressure control valve and is communicated with the upward degassing pipeline, and the pipeline communication point is located between the degassing tank 104 and the pressure control valve.

[0049] The stripping tank 105 is provided with a stripping tank feeding port, a stripping gas inlet, a stripping tank gas phase discharge pipeline and a stripping tank liquid phase discharge pipeline, and the stripping tank feeding port is connected with the degassing tank liquid phase discharge pipeline.

[0050] In order to avoid the influence of the carbon dioxide gas generated in the pipeline mixer on the plug flow of the pipeline medium and the pipeline vibration and the influence on the pH value measuring precision, the pipeline mixer 102 outlet pipeline is divided into two branches in the application, one branch is an upward degassing pipeline and the other branch is a downward liquid pipeline, and the liquid pipeline sends the liquid phase medium into the degassing tank for gas-liquid separation again.

[0051] The pH value detector and the acid pump 102 form a control loop, so that the automatic detection and control of the pH value are easy to realize, the cost is low, and the maintenance is easy.

[0052] Specifically, the downward liquid pipeline is provided with a vertical pipe and a horizontal pipe, a pipeline elbow is arranged between the vertical pipe and the horizontal pipe, and the vertical pipe height is not less than the static liquid column height corresponding to the pipeline pressure drop between the gas-liquid pipeline branch point of the pipeline mixer outlet pipeline and the degassing tank feeding port.

[0053] The liquid pipe diameter is determined according to the treatment amount of the waste lye 1, so that the conveying flow rate of the liquid phase is calculated. Generally, the liquid flow rate in the downward liquid pipeline is 0.1-1.5 m / s, and the preferred liquid flow rate is 0.3-0.8 m / s. According to the Reynolds number formula Re=ρDv / μ (ρ is density, D is pipe diameter, v is flow rate, and μ is viscosity), the calculated Re is compared with 2100, if Re<2100, then ΔP1=8μvL / r is adopted, and if Re≥2100, then ΔP2=ρgL is adopted. 2Calculate the pressure drop in the straight pipe; if Re > 2100, then use ΔP1 = λ(L / D)(ρv 2 / 2) Calculate the pressure drop in the straight pipe (L is the pipe length, R is the pipe radius, λ is the drag coefficient, for Newtonian fluid λ=0.3116 / Re) 0.25 Adding the local pressure drop ΔP2 at elbows and reducers, we get the total pressure drop ΔP. The height of the static liquid column h = ΔP / ρg, and the minimum height of the static liquid column in the downward liquid phase pipeline is h.

[0054] Optionally, the distance between the pH meter and the pipeline bend should be no less than 10D, preferably 15D to 30D, where D is the pipeline diameter.

[0055] Specifically, the diameter of the downward liquid line should not be less than the diameter of the outlet line of the pipe mixer, and preferably the diameter of the downward liquid line should be one to two sizes larger than the diameter of the outlet line of the pipe mixer. For example, if the outlet line diameter of the pipe mixer is DN80, then the diameter of the downward liquid line should be DN100.

[0056] According to a preferred embodiment of the present invention, a liquid level control valve is provided on the liquid phase discharge pipeline of the degassing tank;

[0057] The stripping gas inlet is located at the lower part of the stripping tank 105;

[0058] The merged pipeline, after being connected to the degassing pipeline and the gas phase discharge pipeline of the degassing tank, is further connected to the gas phase discharge pipeline of the stripping tank.

[0059] The present invention will be described in more detail below through embodiments.

[0060] Example 1

[0061] As shown in the attached document Figure 1 The neutralization reaction pH measurement device shown includes: acid storage tank 101, acid pump 102, pipeline mixer 103, pH meter, degassing tank 104 and stripping tank 105;

[0062] The discharge pipeline of acid storage tank 101 is connected in sequence to acid pump 102 and pipeline mixer 103;

[0063] The pipeline mixer 103 is equipped with a waste alkali inlet pipeline and a pipeline mixer outlet pipeline. The pipeline mixer outlet pipeline is divided into two branches: one is an upward degassing pipeline and the other is a downward liquid pipeline. The downward liquid pipeline is connected to the inlet of the degassing tank. The pH value detector is installed on the horizontal pipe of the downward liquid pipeline and forms a control loop with the acid pump 102.

[0064] The degassing tank 104 is provided with a degassing tank gas phase discharge pipeline and a degassing tank liquid phase discharge pipeline, and a pressure control valve is arranged on the degassing tank gas phase discharge pipeline and is communicated with the upward degassing pipeline, and the pipeline communication point is located between the degassing tank 104 and the pressure control valve;

[0065] The blow tank 105 is provided with a blow tank feed inlet, a blow gas inlet, a blow tank gas phase discharge pipeline and a blow tank liquid phase discharge pipeline, and the blow tank feed inlet is connected with the degassing tank liquid phase discharge pipeline.

[0066] The neutralization reaction pH value accurate measurement method using the above device comprises:

[0067] The waste lye 1 is directly sent into the pipeline mixer 103, the sulfuric acid in the acid storage tank 101 is pumped into the pipeline mixer 103 through the acid pump 102, the sulfuric acid and the waste lye are fully mixed in the pipeline mixer, an acid-base neutralization reaction is carried out, the sulfide in the solution is converted into sulfate, and the carbonate is converted into CO2. The 1# neutralized waste lye 2 exits the pipeline mixer 103, obtains 1# acid gas 5 in the upward degassing pipeline, and obtains 2# neutralized waste lye 4 in the downward liquid pipeline, the 2# neutralized waste lye 4 is sent into the degassing tank 104 to further separate the acid gas entrained in the liquid phase, and 2# acid gas 6 exits the degassing tank 104 and is sent to a downstream acid gas treatment device after being combined with 1# acid gas 5. The neutralized waste lye 7 from which the acid gas is removed exits from the bottom of the degassing tank 104 and is sent into the blow tank 105 to further reduce the acid gas in the liquid phase by using blow gas (such as nitrogen), and the blow tank 105 is sent to a downstream sewage treatment device. The 2# neutralized waste lye 4 is provided with a pH value detector on the horizontal pipeline, the pH value detector and the sulfuric acid pump 102 constitute a control loop, and the injection amount of sulfuric acid is adjusted by detecting the pH value of the 2# neutralized waste lye 4 to adjust the stroke of the pump.

[0068] The detailed composition of the waste lye 1 in the embodiment is shown in Table 1, the treatment amount of the waste lye 1 is 25 t / h, the pipe diameter of the pipeline mixer is DN80, the pipe diameter of the upward gas phase pipeline is DN25, the pipe diameter of the downward liquid phase pipeline is DN100, and the flow velocity in the liquid phase pipeline is controlled to be 0.3-0.45 m / s. The static liquid column height of the liquid phase pipeline below the gas-liquid phase branch point is 3 m, and the distance between the pH value detector and the elbow is 2.0 m (20D).

[0069] The acid used in the embodiment is 98% concentrated sulfuric acid, the outlet pressure of the acid pump 102 is 0.8 MPaG, the pressure of the degassing tank 104 is 0.55 MPaG, and the pressure of the blow tank 105 is 0.15 MPaG. The properties of the lye 9 after the neutralization treatment are shown in Table 2. The lye after the treatment mainly contains sodium sulfate sodium salt.

[0070] From the above neutralization reaction pH value accurate measurement method and the nature of the treated lye in Table 2, it can be seen that the embodiment has the advantages of high pH value detection accuracy, sensitive adjustment, stable operation and low cost.

[0071] Table 1 waste lye water quality analysis parameters

[0072]

[0073] Table 2 nature of the treated lye

[0074]

[0075]

[0076] Example 2

[0077] As Figure 2 shown, the reaction process conditions of the embodiment are the same as those of Example 1, and the difference is that a liquid level control valve is provided on the waste lye 7 pipeline, and the speed of the pH value adjusting pump is detected to adjust the injection amount of sulfuric acid. From the neutralization reaction pH value accurate measurement method of the embodiment, it can be seen that the embodiment also has the advantages of high pH value detection accuracy, sensitive adjustment, stable operation and low cost.

[0078] Example 3

[0079] As Figure 3 shown, the process of the embodiment is basically the same as that of Examples 1 and 2, and the difference is that the 1# acid gas 5 produced by the pipeline mixer, the 2# acid gas 6 produced by the degassing tank 104, and the 3# acid gas 8 produced by the stripping tank 105 are mixed together and sent to the downstream acid gas treatment device. The stripping gas used in the embodiment is low-pressure steam of 0.35 MPaG, which strips out the trace amounts of H2S and CO2 entrained in the waste lye 9 after neutralization, and provides qualified water for the downstream wastewater treatment device. At the same time, the generated acid gas is transported to the downstream device in a sealed manner, minimizing the impact on the environment.

[0080] The above has described various embodiments of the present application, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for accurate measurement of neutralization reaction pH, characterized by, The method comprises: (1) the acid (3) in the acid storage tank (101) is sent into the pipeline mixer (103) by the acid pump (102) to mix with the waste lye (1) sent by the waste lye feeding pipeline and to carry out neutralization reaction, so as to obtain 1# neutralized waste lye (2); (2) the 1# neutralized waste lye (2) leaves the outlet pipeline of the pipeline mixer (103), wherein the gas phase 1# acidic gas (5) enters the upward degassing pipeline, and the liquid phase 2# neutralized waste lye (4) enters the downward liquid pipeline; (3) the pH value of the 2# neutralized waste lye (4) is detected by the pH detector, and the acid injection amount of the acid pump (102) into the pipeline mixer (103) is adjusted based on the pH value; the downward liquid pipeline comprises a vertical pipe and a horizontal pipe, and the pH detector is arranged on the horizontal pipe of the downward liquid pipeline; (4) the 2# neutralized waste lye (4) is sent into the degassing tank (104) through the downward liquid pipeline to carry out gas-liquid separation, the obtained gas phase 2# acidic gas (6) is discharged through the degassing tank gas phase discharge pipeline and mixed with the 1# acidic gas (5) to be sent into a downstream acid gas treatment device; the obtained liquid phase neutralized waste lye (7) is sent into the stripping tank (105) through the degassing tank liquid phase discharge pipeline to be stripped by stripping gas (10); (5) the gas phase 3# acidic gas (8) and the liquid phase neutralized waste lye (9) obtained by stripping are sent into a downstream acid gas treatment device and a sewage treatment device through the stripping tank gas phase discharge pipeline and the stripping tank liquid phase discharge pipeline respectively; A pipeline elbow is arranged between the vertical pipe and the horizontal pipe, the height of the vertical pipe is not less than the height of the static liquid column corresponding to the pipeline pressure drop between the gas-liquid pipeline branch point of the outlet pipeline of the pipeline mixer and the feed inlet of the degassing tank; The distance between the pH detector and the pipeline elbow is not less than 10D; The diameter of the downward liquid pipeline is not less than the diameter of the outlet pipeline of the pipeline mixer.

2. The method of claim 1, wherein the neutralization reaction pH is measured accurately. The waste lye (1) comprises at least one of ethylene waste lye and oil refining waste lye; the acid (3) is selected from at least one of sulfuric acid, hydrochloric acid and nitric acid.

3. The method of claim 1, wherein the neutral reaction pH is measured accurately. The acid (3) is concentrated sulfuric acid.

4. The method of claim 1, wherein the neutral reaction pH is measured accurately. The flow rate of the liquid phase 2# neutralized waste lye (4) is 0.1-1.5 m / s.

5. The method of claim 1, wherein the neutralization reaction pH is measured accurately. The flow rate of the liquid phase 2# neutralized waste lye (4) is 0.3-0.8 m / s.

6. The method of claim 1, wherein the neutralization reaction pH is measured accurately. The stripping gas is selected from at least one of low-pressure steam, nitrogen, air and oxygen.

7. The method of claim 1, wherein the neutralization reaction pH is measured accurately. The stripping gas is low-pressure steam and / or air.

8. The method of claim 1, wherein the neutralization reaction pH is measured accurately. The acid injection amount is adjusted by the rotation speed or stroke of the acid pump (102).

9. The method of claim 1, wherein the neutralization reaction pH is measured accurately. The acid injection amount is adjusted by the stroke of the acid pump (102).

10. A device for accurate measurement of neutralization reaction pH, characterized by, The pH value accurate measurement device comprises an acid storage tank (101), an acid pump (102), a pipeline mixer (103), a pH detector, a degassing tank (104) and a stripping tank (105); The discharge pipeline of the acid storage tank (101) is connected to the acid pump (102) and the pipeline mixer (103) in sequence; The pipeline mixer (103) is provided with a waste lye feeding pipeline and a pipeline mixer outlet pipeline, the pipeline mixer outlet pipeline is divided into two branches, one is an upward degassing pipeline and the other is a downward liquid pipeline, the downward liquid pipeline is connected with a degassing tank feeding port, the pH detector is arranged on a horizontal pipe of the downward liquid pipeline and forms a control loop with an acid pump (102); The degassing tank (104) is provided with a degassing tank gas phase discharge pipeline and a degassing tank liquid phase discharge pipeline, the degassing tank gas phase discharge pipeline is provided with a pressure control valve and is communicated with the upward degassing pipeline, the pipeline communication point is located between the degassing tank (104) and the pressure control valve; The stripping tank (105) is provided with a stripping tank feeding port, a stripping gas inlet, a stripping tank gas phase discharge pipeline and a stripping tank liquid phase discharge pipeline, the stripping tank feeding port is connected with the degassing tank liquid phase discharge pipeline; The downward liquid pipeline is provided with a vertical pipe and a horizontal pipe, a pipeline elbow is arranged between the vertical pipe and the horizontal pipe, the vertical pipe height is not less than the static liquid column height corresponding to the pipeline pressure drop between the pipeline mixer outlet pipeline gas-liquid pipeline branch point and the degassing tank feeding port; The distance between the pH detector and the pipeline elbow is not less than 10D, wherein D is the pipeline diameter; The diameter of the downward liquid pipeline is not less than the diameter of the pipeline mixer outlet pipeline.

11. The neutralization reaction pH accuracy measuring device according to claim 10, wherein The distance between the pH detector and the pipeline elbow is not less than 15D-30D.

12. The neutralization reaction pH precision measuring device according to claim 10, wherein, The diameter of the downward liquid pipeline is one to two levels larger than the diameter of the pipeline mixer outlet pipeline.

13. The neutralization reaction pH precision measuring device according to claim 10, wherein The degassing tank liquid phase discharge pipeline is provided with a liquid level control valve; The stripping gas inlet is arranged at the lower part of the stripping tank (105); The combined pipeline after the degassing pipeline is communicated with the degassing tank gas phase discharge pipeline is further communicated with the stripping tank gas phase discharge pipeline.

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