CN114591757B

CN114591757B - Recovery method of waste oil in petroleum refining electric desalting waste liquid and application thereof

Info

Publication number: CN114591757B
Application number: CN202011403423.XA
Authority: CN
Inventors: 张华�; 吴百春; 张晓飞; 李兴春; 刘译阳
Original assignee: Petrochina Co Ltd; CNPC Research Institute of Safety and Environmental Technology Co Ltd
Current assignee: Petrochina Co Ltd; CNPC Research Institute of Safety and Environmental Technology Co Ltd
Priority date: 2020-12-04
Filing date: 2020-12-04
Publication date: 2023-10-27
Anticipated expiration: 2040-12-04
Also published as: CN114591757A

Abstract

The application provides a recovery method of waste oil in petroleum refining electric desalting waste liquid and application thereof. The recovery method comprises the steps of S1, placing electric desalting back flush waste liquid in a multipolar induction electric field for demulsification treatment to obtain demulsified liquid, wherein the electric field of the multipolar induction electric field belongs to a pulse electric field, and the voltage is less than or equal to 25V and the frequency is 20-75 Hz; s2, performing oil-water separation treatment on the demulsification liquid to obtain solid-containing waste oil and deoiled waste water; and S3, carrying out solid-liquid separation on the solid-containing waste oil to obtain the waste oil. By applying the technical scheme of the application, the emulsified oil is aggregated by a three-step method, so that the water-oil separation is realized. Firstly, a low-voltage low-frequency pulse electric field is applied to the waste liquid by utilizing a multipolar induction electric field formed by multipolar induction electrodes, so that demulsification of the electric desalting waste liquid is realized. And secondly, obtaining the waste oil containing the solid phase by adopting an oil-water separation technology. Finally, a solid-liquid separation technology is adopted to obtain waste oil. The recovery method is environment-friendly, energy-saving and efficient.

Description

Recovery method of waste oil in petroleum refining electric desalting waste liquid and application thereof

Technical Field

The application relates to the technical field of oil-containing emulsified wastewater recycling treatment, in particular to a method for recycling waste oil in petroleum refining electric desalting waste liquid and application thereof.

Background

Domestic refineries increasingly rely on low-cost import low-quality heavy oil to maintain production scale and competitiveness, but the special properties of such low-quality crude oil increase the difficulty of petroleum refining. The electric desalting is the first process of petroleum refining, the oil-water separation effect in the electric desalting tank is poor and the desalting efficiency is low due to serious emulsification of crude oil, and a large amount of emulsification layers in the desalting tank are often discharged into wastewater in order to ensure the quality of desalted crude oil by partial enterprises, so that electric desalting wastewater is obtained. The electro-desalting wastewater, particularly colloid, asphaltene and naphthenic acid in the back flush wastewater enter a biochemical system, are difficult to biodegrade, have strong biotoxicity, often cause the breakdown of the biochemical system, and also cause serious foam problems in a biochemical tank. Fine particles in poor crude oil also enter wastewater, and the concentration of total suspended matters is increased, so that the fine particles are easy to deposit in pipelines and treatment facilities, and the wastewater treatment capacity and residence time are reduced.

At present, the petroleum and petrochemical industry has more researches on crude oil emulsification, but has less researches on the influence of crude oil emulsification on petroleum refining, and when the conventional process is difficult to solve the problem of emulsification of oily wastewater, a more targeted treatment technology is needed. The chemical agent degreasing method is simple to operate, but the agent cost is high, and the chemical agent remains in the effluent or forms precipitated sludge, so the chemical agent degreasing method is not a green technology; the heat treatment, the centrifugation, the membrane technology and the like do not need to add medicaments, but in actual operation, the heat treatment, the centrifugation and the like have high energy consumption, and the membrane or the adsorption technology also has the pollution problem of the membrane and the adsorption material. Compared with the chemical agent adding, the biological treatment technology has low cost, is often used for treating organic pollutants in industrial wastewater, but some organic matters in the industrial wastewater are difficult to biodegrade and have high biotoxicity.

Disclosure of Invention

The application mainly aims to provide a recovery method and application of waste oil in petroleum refining electric desalting waste liquid, so as to solve the problems of high energy consumption and serious pollution in the process of recovering waste oil in backwash waste liquid in the prior art.

In order to achieve the above object, according to one aspect of the present application, there is provided a method for recovering waste oil from an electric desalting waste liquid for petroleum refining, comprising: step S1, placing electric desalting back flush waste liquid in a multipolar induction electric field to carry out demulsification treatment to obtain demulsification liquid, wherein the electric field of the multipolar induction electric field belongs to a pulse electric field, the voltage is less than or equal to 25V, and the frequency is 20-75 Hz; s2, performing oil-water separation treatment on the demulsification liquid to obtain solid-containing waste oil and deoiled waste water; and S3, carrying out solid-liquid separation on the solid-containing waste oil to obtain the waste oil.

Preferably, stirring is performed during the demulsification treatment, preferably magnetic stirring, and the treatment time of the demulsification treatment is preferably 5-30 min.

Preferably, the oil-water separation treatment in the step S2 includes an air float method, and S2 preferably includes: continuously introducing air into the demulsification liquid, and taking the upper oil phase to obtain solid-containing waste oil, wherein the air introduction time is preferably 5-25 min.

Preferably, the step S3 includes: filtering the solid-containing waste oil, preferably by a filter screen with the aperture less than or equal to 1 mm.

Preferably, the above recovery method further comprises: and (3) repeating the steps S1-S2 to treat the deoiled waste water to obtain solid-containing waste oil, and performing solid-liquid separation treatment on the solid-containing waste oil by adopting the step S3.

Preferably, the content of waste oil in the electric desalting waste liquid is more than or equal to 1200mg/L, the content of COD is more than or equal to 5000mg/L, and the electric conductivity of the electric desalting waste liquid is 600 mu s/cm-2000 mu s/cm.

According to another aspect of the present application, there is provided a method for treating chemical wastewater, the method comprising: step A1, mixing waste oil, a surfactant and inorganic acid to form a liquid film raw material, wherein the concentration of hydrogen ions in the inorganic acid is preferably 1-2 mol/L, and the waste oil is obtained by any one of the recovery methods; a2, performing liquid film treatment on the chemical wastewater by using a liquid film raw material to obtain layered liquid; and A3, separating the upper liquid of the layered liquid to obtain the emulsion containing pollutants.

Preferably, the surfactant is a nonionic surfactant, preferably the nonionic surfactant is one of span 80, tween 80, alkylphenol polyether, isomeric tridecanol ether and fatty acid methyl ester ethoxylate, and the amount of the surfactant is preferably 2-6% of the mass of the chemical wastewater.

Preferably, the step A1 is carried out by stirring for the first time, preferably at a speed of 2000-4000 r/min for 5-15 min.

Preferably, the step A2 includes: step A21, stirring the chemical wastewater for the second time and simultaneously adding a liquid film raw material, wherein the volume ratio of the liquid film raw material to the chemical wastewater is 1:200-1:50, preferably the speed of the second stirring is 200-600 r/min, the time of the second stirring is 10-30 min, and preferably the adding speed of the liquid film raw material is 2-10 mL/min; and step A22, standing after stirring is completed, and obtaining layered liquid.

Preferably, the above processing method further includes: and performing demulsification treatment on the emulsion containing the pollutants, and then performing sedimentation to obtain upper regenerated waste oil and lower waste water, wherein the demulsification treatment is preferably performed on the emulsion containing the pollutants at 40-60 ℃, and the sedimentation is preferably performed by adopting a mode of standing for 10-20 min.

By applying the technical scheme of the application, the emulsified oil is aggregated by a three-step method, so that the water-oil separation is realized. Firstly, a low-voltage low-frequency pulse electric field is applied to the waste liquid by utilizing a multipolar induction electric field formed by multipolar induction electrodes, so that demulsification of the electric desalting waste liquid is realized. Under the action of an electric field, the emulsified oil can generate electric induction and polarization phenomena, and induction electrodes are formed at two ends of the emulsified oil to reduce the mechanical strength of an interface of an emulsion dispersion system, so that the collision frequency and the coalescence probability of the emulsified oil are increased. Meanwhile, the small oil drops are arranged in a chain shape in the direction of an electric field by the induction electrode, the adjacent oil drops are attracted to each other, so that the emulsified oil in the system collides with each other to form the small oil drops, and the small oil drops continuously collide and then are aggregated to form large oil drops. And secondly, obtaining the waste oil containing the solid phase by adopting an oil-water separation technology. Finally, a solid-liquid separation technology is adopted to obtain waste oil. According to the method disclosed by the application, under the condition that no medicament polluting the environment is added, a pulse electric field with the power not higher than 75Hz and the power not higher than 25V is utilized, so that on one hand, the energy consumption is reduced, on the other hand, the scaling of the polar plate can be reduced in a low-frequency pulse electric field, the demulsification of the electric desalting waste liquid is realized, and further, the waste oil recovery is realized, and the method is green, environment-friendly, energy-saving and efficient.

Detailed Description

It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other. The present application will be described in detail with reference to examples.

As analyzed by the background technology of the application, the prior art solves the problems of serious pollution and high energy consumption when the oil is removed by adopting chemical agents, heat treatment, centrifugation or membrane technology in the emulsification of the oil-containing waste liquid. In order to solve the above problems, the present application provides a recovery method of waste oil in petroleum refining electro-desalting waste liquid, comprising: step S1, placing electric desalting back flushing waste liquid in a multipolar induction electric field for demulsification treatment, wherein the electric field of the multipolar induction electric field belongs to a pulse electric field, so as to obtain demulsified liquid, and the electric field voltage of the electric field is less than or equal to 25V and the frequency is 20-75 Hz; s2, performing oil-water separation treatment on the demulsification liquid to obtain solid-containing waste oil and deoiled waste water; and S3, carrying out solid-liquid separation on the solid-containing waste oil to obtain the waste oil.

The emulsified oil in the electric desalting waste liquid is dispersed in the waste liquid to form stable emulsion. In order to gather the emulsified oil and further realize water-oil separation, the application adopts a three-step method to treat the waste liquid. Firstly, a low-voltage low-frequency pulse electric field is applied to the waste liquid by utilizing a multipolar induction electric field formed by multipolar induction electrodes, so that demulsification of the electric desalting waste liquid is realized. Under the action of an electric field, the emulsified oil can generate electric induction and polarization phenomena, and induction electrodes are formed at two ends of the emulsified oil to reduce the mechanical strength of an interface of an emulsion dispersion system, so that the collision frequency and the coalescence probability of the emulsified oil are increased. Meanwhile, the small oil drops are arranged in a chain shape in the direction of an electric field by the induction electrode, the adjacent oil drops are attracted to each other, so that the emulsified oil in the system collides with each other to form the small oil drops, and the small oil drops continuously collide and then are aggregated to form large oil drops. And secondly, obtaining the waste oil containing the solid phase by adopting an oil-water separation technology. Finally, a solid-liquid separation technology is adopted to obtain waste oil. According to the method disclosed by the application, under the condition that no medicament polluting the environment is added, a pulse electric field with the power not higher than 75Hz and the power not higher than 25V is utilized, so that on one hand, the energy consumption is reduced, on the other hand, the scaling of the polar plate can be reduced in a low-frequency pulse electric field, the demulsification of the electric desalting waste liquid is realized, and further, the waste oil recovery is realized, and the method is green, environment-friendly, energy-saving and efficient.

In order to ensure the demulsification effect of the electric field and separate as much waste oil as possible, the stirring is preferably magnetic stirring in the demulsification treatment process, and the treatment time of the demulsification treatment is preferably 5-30 min.

In one embodiment, the oil-water separation treatment in the step S2 includes an air-float method, and preferably the step S2 includes: continuously introducing air into the demulsification liquid, and taking the upper oil phase to obtain solid-containing waste oil, wherein the air introduction time is preferably 5-25 min. Air bubbles are introduced into the waste liquid for forming large oil drops, so that the oil drops are adhered to the bubbles, the bubbles float upwards together with the oil drops under the buoyancy action, the oil delamination is realized, and the solid waste oil is obtained after the oil-water separation treatment. The above-mentioned air-float process and oil-water separation process are common separation means, and specific operation means can be referred to by those skilled in the art by referring to the prior art, and are not described herein again.

In order to achieve better solid-liquid separation effect, the step S3 includes: the solid-containing waste oil is filtered, and according to the granularity and physical properties of the solid phase in the solid-containing waste oil, a stainless steel screen with the aperture less than or equal to 1mm is preferably adopted for filtering. The specific operation method can refer to the prior art, and is not described herein.

In order to reduce the waste oil content in the electric desalting waste liquid as much as possible, the above recovery method further comprises: and (3) repeating the steps S1-S2 to treat the deoiled waste water to obtain solid-containing waste oil, and performing solid-liquid separation treatment on the solid-containing waste oil by adopting the step S3.

In one embodiment, the content of waste oil in the electric desalting waste liquid is more than or equal to 1200mg/L, the content of COD is more than or equal to 5000mg/L, and the electric conductivity of the electric desalting waste liquid is 600 mu s/cm-2000 mu s/cm. The treatment method can treat the backwash electric desalting waste liquid which cannot be treated in the prior art and has higher oil content, effectively reduces the content of waste oil in the electric desalting waste liquid to below 90mg/L, and avoids pollution and economic loss caused by excessive oil discharged along with the waste water.

In an exemplary embodiment of the present application, there is provided a chemical wastewater treatment method including: a1, mixing waste oil, a surfactant and an inorganic acid to form a liquid film raw material, wherein the concentration of the inorganic acid is preferably 1-2 mol/L, and the waste oil is obtained by any one of the recovery methods; a2, performing liquid film treatment on the chemical wastewater by using a liquid film raw material to obtain layered liquid; and A3, separating the upper liquid of the layered liquid to obtain the emulsion containing pollutants.

According to the application, the waste oil recovered from the electric desalting waste liquid is used as a solvent in a liquid film technology for the first time, chemical waste water (such as aniline waste water) is treated, and harmful substances such as low-concentration heavy metals, organic acids, amines and the like in the chemical waste water are effectively recovered, so that the reutilization of the waste oil is realized. Specifically, the method takes waste oil as a solvent, and adds a surfactant for stabilizing water in an oil phase and acid as a back-extraction agent to form a liquid film raw material, so that the liquid film raw material performs liquid film treatment on chemical wastewater, and then separates the oil phase to effectively complete separation of pollutants in the chemical wastewater.

Preferably, the surfactant is a nonionic surfactant, preferably the nonionic surfactant is one of span 80, tween 80, alkylphenol polyether, isomeric tridecanol ether and fatty acid methyl ester ethoxylate, and the surfactant not only can improve the stability of the liquid film raw material as much as possible, but also has better acid resistance and is easy to break emulsion, so that the oil phase can be repeatedly used. Further, the concentration of the surfactant is preferably 2 to 6% to enhance the effect of stabilizing the water in the oil phase.

In one embodiment, the step A1 is a mixing process by a first stirring, preferably at a speed of 2000 to 4000r/min for 5 to 15min. Through high-speed stirring, solvent oil, surfactant and acid are fully mixed, and the effect of a liquid film technology is improved.

In one embodiment, the step A2 includes: step A21, stirring the chemical wastewater for the second time and simultaneously adding a liquid film raw material, wherein the volume ratio of the liquid film raw material to the chemical wastewater is 1:200-1:50, preferably the speed of the second stirring is 200-600 r/min, the time of the second stirring is 10-30 min, and preferably the adding speed of the liquid film raw material is 2-10 mL/min; and step A22, standing after stirring is completed, and obtaining layered liquid. Through the stirring, standing and layering, the adding speed of the liquid film raw materials is controlled, so that the liquid film and the chemical wastewater are fully mixed, and as many target pollutants in the chemical wastewater as possible enter stripping agent acid in the liquid film, thereby realizing the separation and recovery of the target pollutants.

In one embodiment, the above processing method further includes: and performing demulsification treatment on the emulsion containing the pollutants, and then performing sedimentation to obtain upper regenerated waste oil and lower waste water, wherein the demulsification treatment is preferably performed on the emulsion containing the pollutants at 40-60 ℃, and the sedimentation is preferably performed by adopting a mode of standing for 10-20 min. And (3) demulsifying the emulsion containing the pollutants in a gravity sedimentation mode to form a layered liquid with an upper layer of regenerated waste oil and a lower layer of waste water containing the pollutants, so that the regeneration of the waste oil is realized, and the regenerated waste oil can be returned to the step A1 for recycling.

The advantageous effects of the present application will be further described below with reference to examples and comparative examples.

Example 1

1) 1L of test water sample (average oil content: 1545mg/L, average COD: 9156mg/L, average conductivity: 1020. Mu.s/cm) was added to a small test device built with dimensionally stable electrodes, and an electric field with a voltage of 5V and a frequency of 50Hz was applied to the test water sample. The reaction process is magnetically stirred, and the residence time is 15min.

2) After demulsification by the electric field, air is introduced to carry out air floatation, the reaction time is 15min, and the waste liquid is layered into upper solid-containing waste oil and lower deoiled waste water.

3) The upper layer solid waste oil is filtered and recovered by a stainless steel screen with the aperture of 1mm, the recovered waste oil quantity is about 10mL, the average oil content is 96.7% by measurement, and the average oil content of the lower layer waste water is 89mg/L.

4) The above treatment is repeatedly carried out on the lower layer waste water until the recovery amount of waste oil is more than or equal to 20mL.

Example 2

The difference from example 1 is that the electric field voltage in 1) is 25V. After the treatment, the recovered waste oil was about 13mL, and the oil content was found to be 97.3% on average, and the oil content of the lower-layer waste water was found to be 55mg/L on average. The above treatment is repeatedly carried out on the lower layer waste water until the recovery amount of waste oil is more than or equal to 20mL.

Example 3

The difference from example 1 is that the electric field frequency in 1) is 20Hz. After the treatment, the recovered waste oil was about 10mL, and the oil content was determined to be 96.3% on average, and the oil content of the lower layer waste water was 90mg/L on average. The above treatment is repeatedly carried out on the lower layer waste water until the recovery amount of waste oil is more than or equal to 20mL.

Example 4

The difference from example 1 is that the electric field frequency in 1) is 75Hz. After the treatment, the recovered waste oil was about 12mL, and the oil content was found to be 97% on average, and the oil content of the lower-layer waste water was found to be 62mg/L on average. The above treatment is repeatedly carried out on the lower layer waste water until the recovery amount of waste oil is more than or equal to 20mL.

Example 5

The difference from example 1 is that the retention time in 1) is 5min. After the treatment, the recovered waste oil was about 8mL, and the oil content was measured to be 90.3% on average, and the oil content of the lower-layer waste water was 150mg/L on average. The above treatment is repeatedly carried out on the lower layer waste water until the recovery amount of waste oil is more than or equal to 20mL.

Example 6

The difference from example 1 is that the retention time in 1) is 30min. The oil content of the treated recovered waste water was about 12mL, and the oil content was measured to be 96.1% on average, and the oil content of the lower layer waste water was 60mg/L on average. The above treatment is repeatedly carried out on the lower layer waste water until the recovery amount of waste oil is more than or equal to 20mL.

Example 7

The difference from example 1 is that the air-flotation reaction time in 2) is 5min. After the treatment, the recovered waste oil was about 8mL, and the oil content was found to be 95.0% on average, and the oil content of the lower-layer waste water was found to be 180mg/L on average. The above treatment is repeatedly carried out on the lower layer waste water until the recovery amount of waste oil is more than or equal to 20mL.

Example 8

The difference from example 1 is that the air-float reaction time in 2) was 25 minutes, the recovered waste oil after the treatment was about 13mL, the oil content was determined to be 96.3% on average, and the oil content of the lower layer waste water was 70mg/L on average. The above treatment is repeatedly carried out on the lower layer waste water until the recovery amount of waste oil is more than or equal to 20mL.

Example 9

The procedure of example 1 was followed, in which 3) the used oil was recovered by filtration through a stainless steel screen having a pore size of 0.5 mm. After the treatment, the recovered waste oil was about 11mL, and the oil content was determined to be 96.9% on average, and the oil content of the lower-layer waste water was 85mg/L on average. The above treatment is repeatedly carried out on the lower layer waste water until the recovery amount of waste oil is more than or equal to 20mL.

Example 10

1) 20mL of the recovered waste oil in example 1 was placed in a 100mL beaker, 200mL of Tween 80, which was 3% of the mass of the aniline production waste water, was added, and then hydrochloric acid solution was added so that the concentration of hydrochloric acid in the mixed solution was 1.5mol/L. Magnetic stirring is carried out at a speed of 3000r/min for 10min until the liquid film raw material is emulsified, and the liquid film raw material with a median particle diameter of about 8.5 mu m is obtained.

2) 200mL of aniline production wastewater (COD content is 850mg/L on average, chromaticity is 700 times on average) is taken in a 500mL beaker. The waste oil liquid film raw material prepared in the step 1) is added dropwise under magnetic stirring at a speed of 400r/min, and the raw material adding speed is 5mL/min. Stirring for 20min while adding to obtain brown pollutant-containing oil layer and waste water with average chromaticity less than 50 times.

3) Taking out the upper emulsion in the step 2), heating to 50 ℃ to realize demulsification in stirring, standing for 15min, separating by gravity sedimentation to form layered liquid, and recovering the upper waste oil to obtain regenerated waste oil. Which can be used again as a solvent in emulsion film treatment to separate contaminants in aniline wastewater.

Example 11

The difference from example 10 is that the hydrochloric acid solution of 1) was changed to sulfuric acid solution, and the concentration of sulfuric acid in the mixed solution was 0.75mol/L. After the treatment of step 1), a liquid film raw material having a median particle diameter of about 8.5 μm was obtained. The upper layer of the wastewater is brown and contains pollutant oil layers and the lower layer of the wastewater with average chromaticity less than 50 times is obtained after the treatment of the step 2).

Example 12

The difference from example 10 is that the concentration of hydrochloric acid in the mixed solution in 1) was 1mol/L. After the treatment of step 1), a liquid film raw material having a median particle diameter of about 9 μm was obtained. The upper layer of the wastewater is brown and contains pollutant oil layers and the lower layer of the wastewater with average chromaticity less than 50 times is obtained after the treatment of the step 2).

Example 13

The difference from example 10 is that the concentration of hydrochloric acid in the mixed solution in 1) was set to 2mol/L. After the treatment of step 1), a liquid film raw material having a median particle diameter of about 8 μm was obtained. The upper layer of the wastewater is brown and contains pollutant oil layers and the lower layer of the wastewater with average chromaticity less than 50 times is obtained after the treatment of the step 2).

Example 14

1) 20mL of the recovered waste oil in example 1 was placed in a 100mL beaker, tween 80 was added at a mass concentration of 3%, and then hydrochloric acid solution was added so that the concentration of hydrochloric acid in the mixed solution was 1.5mol/L. Magnetic stirring is carried out at a speed of 3000r/min for 10min until the liquid film raw material is emulsified, and the liquid film raw material with a median particle diameter of about 8.5 mu m is obtained.

2) 200mL of purified water (average COD content: 1100mg/L, phenol content: about 60 mg/L) from petroleum refining sour water stripping was placed in a 500mL beaker. The waste oil emulsion prepared in step 1) above was added dropwise with magnetic stirring at a speed of 400 r/min. Stirring and reacting for 20min to obtain the wastewater with the average phenol content of the upper layer of the dye oil layer and the lower layer of the dye oil layer less than 1 mg/L.

Example 15

The difference from example 10 is that 1) tween 80 was changed to span 80, and after the treatment of step 1), a liquid film material having a median particle diameter of about 8 μm was obtained. The upper layer of the wastewater is brown and contains pollutant oil layers and the lower layer of the wastewater with average chromaticity less than 50 times is obtained after the treatment of the step 2).

Example 16

The difference from example 10 is that, in 1), tween 80 was replaced with alkylphenol polyether, and after the treatment of step 1), a liquid film material having a median particle diameter of about 8.5 μm was obtained. The upper layer of the wastewater is brown and contains pollutant oil layers and the lower layer of the wastewater with average chromaticity less than 50 times is obtained after the treatment of the step 2).

Example 17

The difference from example 10 is that, in 1), tween 80 was changed to a fatty acid methyl ester ethoxylate, and after the treatment of step 1), a liquid film material having a median particle diameter of about 8.6 μm was obtained. The upper layer of the wastewater is brown and contains pollutant oil layers and the lower layer of the wastewater with average chromaticity less than 50 times is obtained after the treatment of the step 2).

Example 18

The difference from example 10 is that, in 1), tween 80 was changed to isotridecyl alcohol ether, and after the treatment in 1), a liquid film material having a median particle diameter of about 8.3 μm was obtained. The upper layer of the wastewater is brown and contains pollutant oil layers and the lower layer of the wastewater with average chromaticity less than 50 times is obtained after the treatment of the step 2).

Example 19

The difference from example 10 is that the mass of Tween 80 in 1) is 2% of the mass of 200mL of aniline production wastewater, and the liquid film raw material with the median diameter of about 9 μm is obtained after the treatment of the step 1). The upper layer of the wastewater is brown and contains pollutant oil layers and the lower layer of the wastewater with average chromaticity less than 50 times is obtained after the treatment of the step 2).

Example 20

The difference from example 10 is that the tween 80 in 1) has a mass concentration of 6% of the mass of 200mL of aniline production wastewater, and after the treatment in step 1), a liquid film raw material with a median particle diameter of about 7.5 μm is obtained. The upper layer of the wastewater is brown and contains pollutant oil layers and the lower layer of the wastewater with average chromaticity less than 50 times is obtained after the treatment of the step 2).

Example 21

The difference from example 10 is that the magnetic stirring at a speed of 2000r/min in 1) is carried out, and after the treatment in step 1), a liquid film raw material having a median particle diameter of about 8.5 μm is obtained. The upper layer of the wastewater is brown and contains pollutant oil layers and the lower layer of the wastewater with average chromaticity less than 50 times is obtained after the treatment of the step 2).

Example 22

The difference from example 10 is that in 1) magnetic stirring is carried out at a speed of 4000r/min, and after the treatment in step 1), a liquid film raw material having a median particle diameter of about 7.5 μm is obtained. The upper layer of the wastewater is brown and contains pollutant oil layers and the lower layer of the wastewater with average chromaticity less than 50 times is obtained after the treatment of the step 2).

Example 23

The difference from example 10 is that the magnetic stirring time in 1) was 5min, and after the treatment in step 1), a liquid film material having a median particle diameter of about 8.5 μm was obtained. The upper layer of the wastewater is brown and contains pollutant oil layers and the lower layer of the wastewater with average chromaticity less than 50 times is obtained after the treatment of the step 2).

Example 24

The difference from example 10 is that the magnetic stirring time in 1) was 15min, and after the treatment in step 1), a liquid film material having a median particle diameter of about 7 μm was obtained. The upper layer of the wastewater is brown and contains pollutant oil layers and the lower layer of the wastewater with average chromaticity less than 50 times is obtained after the treatment of the step 2).

Example 25

The difference from example 10 is that the magnetic stirring speed in 2) is 200r/min. The upper layer of the wastewater is brown and contains pollutant oil layers and the lower layer of the wastewater with average chromaticity less than 50 times is obtained after the treatment of the step 2).

Example 26

The difference from example 10 is that the magnetic stirring speed in 2) is 600r/min. The upper layer of the wastewater is brown and contains pollutant oil layers and the lower layer of the wastewater with average chromaticity less than 50 times is obtained after the treatment of the step 2).

Example 27

The difference from example 10 is that the magnetic stirring time in 2) is 10min. The upper layer of the wastewater is brown and contains pollutant oil layers and the lower layer of the wastewater with average chromaticity less than 50 times is obtained after the treatment of the step 2).

Example 28

The difference from example 10 is that the magnetic stirring time in 2) is 30min. The upper layer of the wastewater is brown and contains pollutant oil layers and the lower layer of the wastewater with average chromaticity less than 50 times is obtained after the treatment of the step 2).

Example 29

The difference from example 10 is that 2) the feed rate was 2mL/min. The upper layer of the wastewater is brown and contains pollutant oil layers and the lower layer of the wastewater with average chromaticity less than 50 times is obtained after the treatment of the step 2).

Example 30

The difference from example 10 is that 2) the feed rate was 10mL/min. The upper layer of the wastewater is brown and contains pollutant oil layers and the lower layer of the wastewater with average chromaticity less than 50 times is obtained after the treatment of the step 2).

Example 31

The difference from example 10 is that the demulsification is effected in 3) by heating to 40℃with stirring. And 3) treating to obtain regenerated waste oil.

Example 32

The difference from example 10 is that the demulsification is effected by heating to 60℃with stirring in 3). And 3) treating to obtain regenerated waste oil.

Example 33

The difference from example 10 is that in 3) a stratified liquid is formed by gravity sedimentation separation after standing for 10min. And 3) treating to obtain regenerated waste oil.

Example 34

The difference from example 10 is that in 3) a stratified liquid is formed by gravity sedimentation separation by standing for 20 min. And 3) treating to obtain regenerated waste oil.

From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:

the emulsified oil in the electric desalting waste liquid is dispersed in the waste liquid to form stable emulsion. In order to gather the emulsified oil and further realize water-oil separation, the application adopts a three-step method to treat the waste liquid. First, a low-voltage low-frequency pulse electric field is applied to the waste liquid to realize demulsification of the electric desalting waste liquid. Under the action of an electric field, the emulsified oil can generate electric induction and polarization phenomena, and induction electrodes are formed at two ends of the emulsified oil to reduce the mechanical strength of an interface of an emulsion dispersion system, so that the collision frequency and the coalescence probability of the emulsified oil are increased. Meanwhile, the small oil drops are arranged in a chain shape in the direction of the electric line of force by the induction electrode, and the small oil drops are attracted to each other in a similar distance, so that the emulsified oil in the system collides with each other to form the small oil drops, and the small oil drops continuously collide and then are aggregated to form the large oil drops. And secondly, obtaining the waste oil containing the solid phase by adopting an oil-water separation technology. Finally, a solid-liquid separation technology is adopted to obtain waste oil. The method disclosed by the application realizes demulsification of the electric desalting waste liquid by using the pulse electric field with the power of not higher than 75Hz and not higher than 20V under the condition of not adding any medicament polluting the environment, thereby realizing waste oil recovery, and is environment-friendly, energy-saving and efficient.

Meanwhile, the waste oil recovered from the electric desalting waste liquid is used as a solvent in a liquid film technology for the first time, chemical waste water (such as aniline waste water) is treated, and harmful substances such as low-concentration heavy metals, organic acids, amines and the like in the chemical waste water are effectively recovered, so that the reutilization of the waste oil is realized. Specifically, the method takes waste oil as a solvent, and adds a surfactant for stabilizing water in an oil phase and acid as a back-extraction agent to form emulsion, so that the emulsion performs liquid film treatment on chemical wastewater, and then separates the oil phase, thereby effectively completing the separation of pollutants in the chemical wastewater.

The above is only a preferred embodiment of the present application, and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for treating chemical wastewater, the method comprising:

step A1, mixing waste oil with a surfactant and inorganic acid to form a liquid film raw material;

a2, performing liquid film treatment on the chemical wastewater by using the liquid film raw material to obtain layered liquid;

step A3, separating the upper liquid of the layered liquid to obtain an emulsion containing pollutants;

the waste oil is recovered from petroleum refining electric desalting waste liquid, and the recovery method comprises the following steps:

step S1, placing electric desalting back flush waste liquid in a multipolar induction electric field to carry out demulsification treatment to obtain demulsification liquid, wherein the electric field of the multipolar induction electric field belongs to a pulse electric field, and the voltage is less than or equal to 25V and the frequency is 20-75 Hz;

s2, carrying out oil-water separation treatment on the demulsification liquid to obtain solid-containing waste oil and deoiled waste water;

and S3, carrying out solid-liquid separation on the solid-containing waste oil to obtain the waste oil.

2. The method according to claim 1, wherein the concentration of hydrogen ions in the inorganic acid is 1 to 2mol/L.

3. The process of claim 1 wherein agitation is performed during the demulsification treatment.

4. A process according to claim 3, wherein the stirring is magnetic stirring.

5. A treatment method according to claim 3, wherein the demulsification treatment is carried out for a treatment time of 5 to 30 minutes.

6. The process according to claim 1, wherein the oil-water separation treatment in step S2 comprises an air-float process.

7. The processing method according to claim 6, wherein the S2 includes:

continuously introducing air into the demulsification liquid, and taking the upper oil phase to obtain the solid-containing waste oil.

8. The method according to claim 7, wherein the air is introduced for a period of 5 to 25 minutes.

9. The processing method according to claim 1, wherein the step S3 includes: filtering the solid-containing waste oil.

10. The method according to claim 9, wherein the filtering is performed by using a filter screen having a pore size of 1mm or less.

11. The process of claim 1 wherein the recovery process further comprises:

and repeating the steps S1 to S2 to treat the deoiled waste water to obtain solid-containing waste oil, and adopting the step S3 to perform solid-liquid separation treatment on the solid-containing waste oil.

12. The method according to claim 1, wherein the waste oil content in the electric desalting waste liquid is not less than 1200mg/L, the COD content is not less than 5000mg/L, and the electric desalting waste liquid has an electric conductivity of 600 to 2000 μs/cm.

13. The method of claim 1, wherein the surfactant is a nonionic surfactant.

14. The method of claim 13, wherein the nonionic surfactant is one of span 80, tween 80, alkylphenol polyether, isotridecyl alcohol ether, fatty acid methyl ester ethoxylate.

15. The method according to claim 13, wherein the amount of the surfactant is 2 to 6% by mass of the chemical wastewater.

16. The method according to claim 1, wherein the step A1 is performed by performing the mixing treatment with a first stirring.

17. The process of claim 16, wherein the first stirring is performed at a speed of 2000 to 4000r/min for a period of 5 to 15 minutes.

18. The method according to claim 1, wherein the step A2 includes:

step A21, stirring the chemical wastewater for the second time and simultaneously adding the liquid film raw material, wherein the volume ratio of the liquid film raw material to the chemical wastewater is 1:200-1:50;

and step A22, standing after stirring is completed, so as to obtain the layered liquid.

19. The method according to claim 18, wherein the speed of the second stirring is 200 to 600r/min, and the time of the second stirring is 10 to 30min.

20. The method according to claim 18, wherein the liquid film raw material is added at a rate of 2 to 10mL/min.

21. The processing method according to claim 1, characterized in that the processing method further comprises:

and performing demulsification treatment on the emulsion containing pollutants, and then performing sedimentation to obtain upper regenerated waste oil and lower waste water.

22. The method according to claim 21, wherein the demulsification treatment is performed at 40 to 60 ℃ on the emulsion containing the contaminants.

23. The method according to claim 21, wherein the sedimentation is performed by standing for 10 to 20 minutes.