Treatment method for polymer sewage reinjection

Abstract

The invention relates to a treatment method for polymer sewage reinjection, which comprises the following steps: pretreating polymer-containing sewage to remove oil and suspended matters; carrying out acidity regulation treatment on the sewage, so that the pH value of the sewage is controlled within a range suitable for oxidation treatment; injecting gas to form a gas-water mixture; the gas-water mixture is fed into an electrochemical oxidation treatment unit with an automatic cleaning function to be subjected to electrolytic oxidation, and treatment parameters are dynamically adjusted through a control module; then carrying out alkaline neutralization treatment on the electrolyzed sewage, and carrying out fine filtration in a solid-liquid separation manner; in the treatment process, the generation condition of byproducts is synchronously monitored, and emission management is carried out. The technical problems that in the prior art, electrode pollution is difficult to clean continuously, and the electrolysis efficiency and the equipment operation stability are affected are solved.

Description

Technical Field

[0001] The present invention is a treatment method for polymer sewage reinjection. Background Art

[0002] In the existing electrolytic oxidation treatment technology for polymer-containing sewage, the problems of electrode pollution and scaling have become the key obstacles restricting its long-term stable operation. Since polymer-containing sewage contains a large amount of high-molecular polymers and complex organic substances, these substances are likely to form a deposition layer on the surfaces of the anode and cathode during the electrolysis process, which is difficult to shed, seriously affecting the effective reaction area and conductivity of the electrodes, resulting in a decrease in electrolysis efficiency, an increase in power consumption, and even causing plate corrosion or system failures. To extend the service life of the equipment and maintain the treatment effect, some existing technologies attempt to automatically clean the electrodes by setting up a mechanical brush structure. However, this type of method usually relies on motor drive, has a complex structure, is easily affected by offshore environmental factors such as high salinity, high humidity, and limited space and fails, and the brushes have problems such as wear, jamming, and rust during long-term operation, requiring frequent maintenance and having poor reliability. Therefore, how to construct a self-cleaning mechanism for electrodes that can achieve high efficiency and continuous operation without manual intervention has become a technical problem that urgently needs to be solved in the current electrolytic treatment system for polymer-containing sewage. Summary of the Invention

[0003] The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art and provide a treatment method for polymer sewage reinjection.

[0004] A treatment method for polymer sewage reinjection includes the following steps:

[0005] Step 1: Pretreat the polymer-containing sewage to remove oil and suspended solids;

[0006] Step 2: Adjust the pH value of the sewage to an appropriate range for oxidation treatment;

[0007] Step 3: Inject gas into the sewage to form a gas-liquid mixture;

[0008] Step 4: Send the gas-liquid mixture into an electrochemically oxidative treatment unit with an automatic cleaning function for electrolytic oxidation treatment, and dynamically adjust the treatment parameters through a control module;

[0009] Step 5: Perform alkaline neutralization treatment on the electrolyzed sewage;

[0010] Step 6: Perform solid-liquid separation treatment on the neutralized sewage;

[0011] Step 7: Monitor and manage the emissions of by-products during the treatment process.

[0012] Further, the pretreatment includes allowing the polymer-containing sewage to stand still in a sedimentation unit for 10 to 20 hours to remove oil and particulate matter.

[0013] Further, the acid adjustment treatment uses inorganic acid or organic acid to adjust the pH value to 3 to 5.

[0014] Further, the gas is air, nitrogen, air-ozone or air-hydrogen peroxide.

[0015] Further, the gas is injected through a micro-nano bubble generating device to form bubbles with a particle size of 20 to 80 μm.

[0016] Further, the electro-chemical oxidation treatment unit includes an anode and a cathode with a corrugated structure, and the electrode spacing is 3 to 5 cm.

[0017] Further, the anode material includes an iron plate electrode, a boron-doped diamond electrode, a metal oxide-coated electrode, etc.

[0018] Further, the automatic cleaning function is realized through a periodic electrode oscillation mechanism.

[0019] Further, the control module automatically adjusts the current density and electrolysis time according to real-time parameters such as sewage conductivity and pollution load.

[0020] Further, the by-product monitoring includes on-line monitoring and automatic discharge control of electrode corrosion products, foam layer, oil sludge and suspended particles.

[0021] Beneficial effects: Compared with the prior art, the treatment method for reinjecting polymer-containing sewage provided by the present invention integrates functions such as pretreatment, pH adjustment, gas-water mixing, electrolytic oxidation, air flotation, neutralization, filtration and by-product monitoring through modular design, forming a set of sewage treatment system with coordination, high efficiency, safety and high automation level. This method mainly aims at the pain points of high polymer viscosity, large oil and suspended solid content, easy electrode pollution, high treatment energy consumption and unstable operation in polymer-containing sewage, and adopts the following five key technologies for optimization, effectively improving the overall operation performance of the system and the feasibility of industrial application.

[0022] First, to solve the problem of easy scaling on the electrode plates during the electrolysis process, the present invention adopts a corrugated structure electrode plate combined with a periodic oscillation cleaning mechanism, which can continuously disturb the electrode surface during the treatment process. With the help of liquid flow shear force and mechanical oscillation, on-line self-cleaning of the electrode plates without shutdown is realized, significantly reducing the maintenance frequency and improving the continuous operation ability of the equipment. This design replaces the traditional brush structure and has the advantages of simple structure and high reliability.

[0023] Secondly, to address the problems of high energy consumption and unstable treatment efficiency in traditional electrolysis systems under load changes, the present invention introduces an intelligent electronic control module. It can collect parameters such as the conductivity, temperature, and polymer concentration of sewage in real time, and automatically adjust the electrolysis current and treatment time to achieve an energy supply-on-demand and dynamic response control strategy. This not only improves the efficiency of the electrolysis reaction but also significantly reduces the energy consumption per unit of water treatment, making it suitable for energy-constrained scenarios such as offshore platforms.

[0024] Regarding the safety hazards brought about by the dependence on chemical aids such as ozone or hydrogen peroxide in traditional flotation processes, the present invention uses micro-nano bubble technology to replace chemical oxidants. By means of high-speed shearing or ceramic aeration, bubbles with a particle size of 20 - 80 μm are formed, which can significantly enhance the flocculation and floating performance of polymers and oil droplets, achieve physical enhanced flotation effects, eliminate safety risks such as explosion and corrosion at the source, and at the same time improve the greenness of operation and the adaptability of equipment.

[0025] In addition, to address the problems of large fluctuations in the quality and complex composition of polymer-containing sewage, the overall system adopts an online monitoring and closed-loop control mechanism. Each unit can automatically and collaboratively adjust the chemical dosage, electrolysis intensity, and filtration intensity according to the front-end pollution load to ensure that the system can still operate stably and meet the standards under different pollutant concentrations and pH conditions, and has good adaptability and scalability.

[0026] Finally, to prevent the risks of secondary pollution and system blockage, the present invention configures a by-product monitoring and centralized collection system in the electrolytic oxidation and filtration modules, which can monitor and regularly discharge sludge, oily sludge, electrode corrosion products, foam layers, etc. in real time, and constructs a closed-loop by-product safety management mechanism to improve the environmental protection and stability of system operation.

[0027] In summary, by introducing a number of key technologies such as electrode self-cleaning, intelligent energy consumption regulation, safe flotation, dynamic response control, and by-product monitoring in the process flow, the present invention comprehensively solves the technical bottlenecks in the treatment of polymer-containing sewage in existing offshore oilfields, and has significant advantages such as high efficiency, low energy consumption, easy operation and maintenance, automation, environmental protection and safety, and has good industrial application prospects and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a flowchart of a treatment method for polymer sewage reinjection. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] To deepen the understanding of the present invention, the following will further elaborate on the present invention in combination with embodiments and drawings. The embodiments are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0030] Embodiment 1: Treatment of reinjection water under standard process conditions

[0031] This embodiment is used to treat the polymer-containing sewage in the produced fluid of an offshore oilfield. The initial concentration of the polymer in the water sample is about 600 mg / L, the viscosity is about 15 mPa·s, the oil content is about 120 mg / L, and the suspended solid content is about 180 mg / L.

[0032] The treatment steps are as follows:

[0033] Pretreatment stage: The sewage is first introduced into an oil removal and sedimentation tank with an oil-water separation function, and the static time is 12 hours to preliminarily separate large particles and floating oil.

[0034] pH adjustment stage: The settled sewage is sent to a pH adjustment tank, and a 5% sulfuric acid solution is automatically added. The pH is controlled to be stable at 4.0 ± 0.2 through an on-line pH monitor to facilitate subsequent electrolytic oxidation.

[0035] Gas-liquid mixing stage: The sewage after pH adjustment is sent to a micro-nano bubble generation system by a pump, air is injected to generate micro-bubbles with an average particle size of 30 μm, and a stable gas-water mixed fluid is formed.

[0036] Electrolytic oxidation - air flotation stage: The gas-water mixture enters an integrated electrolytic oxidation - air flotation treatment device, and the specific parameters are as follows:

[0037] Anode: Boron-doped diamond (BDD) corrugated plate;

[0038] Cathode: Stainless steel corrugated plate;

[0039] Plate spacing: 3 cm;

[0040] Configure an electrode low-frequency oscillation structure, which oscillates once every 10 minutes with an amplitude of 1 cm;

[0041] Configure an intelligent control module to automatically identify the conductivity of the water sample and adjust the current intensity to 2.5 A, the voltage is 25 V, and the treatment time is 15 minutes.

[0042] Neutralization and buffering stage: The electrolyzed sewage enters a buffer tank, and a 5% sodium hydroxide solution is automatically added to adjust the pH value to 7.5 ± 0.2.

[0043] Deep filtration stage: The neutralized sewage enters a series filtration system composed of modified fiber balls + quartz sand particles, and the filtration speed is 8 m / h, and the effluent meets the re-injection water quality standard.

[0044] By-product monitoring and treatment: By-product monitoring modules are provided at the bottom of the electrolysis device and the filtration system to continuously monitor the sludge concentration and particle load through on-line sensors, and a timed sewage discharge system is provided to clean the residue every 24 hours.

[0045] The treatment effect is shown in Table 1 below:

[0046] Item Before treatment After treatment Polymer concentration 600mg / L 600mg / L Oil content 120mg / L 120mg / L Suspended solids 180mg / L 180mg / L pH value 6.2 6.2

[0047] Table 1

[0048] Example Two: Energy-saving Optimization Parameter Conditions

[0049] In another practical application scenario, in order to adapt to the condition of tight power supply, the following energy-saving process parameters are adopted:

[0050] The pH is adjusted using 3% acetic acid solution, and the target pH = 4.5;

[0051] In the micro-nano bubble system, no external oxidant is used, and only normal-pressure air is injected;

[0052] The electrolysis current is set to 1.5 A, the voltage is 20 V, and the time is 20 minutes;

[0053] The anode is an iron-plated titanium dioxide electrode plate, the cathode is a graphite plate, and the electrode plate spacing is 4 cm;

[0054] Neutralization is carried out with 5% ammonia water, and the final pH value is controlled at 7.2;

[0055] The filtration system is the same.

[0056] The power consumption of this scheme is further reduced by 20%, which is applicable to medium- and low-concentration polymer sewage or offshore platforms with energy constraints.

[0057] Working principle: Through modular design, functions such as pretreatment, pH adjustment, gas-water mixing, electrolytic oxidation, air flotation, neutralization, filtration, and by-product monitoring are integrated into one, forming a set of sewage treatment system with coordination, high efficiency, safety, and high automation level. This method mainly aims at the pain points of high polymer viscosity, large oil and suspended solid content, easy electrode pollution, high treatment energy consumption, and unstable operation in polymer-containing sewage. The following five key technologies are adopted for optimization, effectively improving the overall operation performance of the system and the feasibility of industrial application.

[0058] First, to solve the problem of easy scaling on the electrode plate during the electrolysis process, the present invention adopts a corrugated structure electrode plate combined with a periodic oscillation cleaning mechanism, which can continuously disturb the electrode surface during the treatment process. With the help of liquid flow shear force and mechanical oscillation, on-line self-cleaning of the electrode plate without stopping the machine is realized, significantly reducing the maintenance frequency and improving the continuous operation ability of the equipment. This design replaces the traditional brush structure and has the advantages of simple structure and high reliability.

[0059] Secondly, to address the problems of high energy consumption and unstable treatment efficiency of traditional electrolysis systems under load changes, the present invention introduces an intelligent electronic control module that can collect parameters such as the conductivity, temperature, and polymer concentration of sewage in real time, and automatically adjust the electrolysis current and treatment time to achieve an energy supply-on-demand and dynamic response control strategy. This not only improves the efficiency of the electrolysis reaction but also significantly reduces the energy consumption per unit of water treatment, making it suitable for energy-constrained scenarios such as offshore platforms.

[0060] To address the safety hazards posed by traditional flotation processes that rely on chemical aids such as ozone or hydrogen peroxide, the present invention uses micro-nano bubble technology to replace chemical oxidants. By means of high-speed shearing or ceramic aeration, bubbles with a particle size of 20-80 μm are formed, which can significantly enhance the flocculation and floating performance of polymers and oil droplets, achieving a physically enhanced flotation effect, eliminating safety risks such as explosion and corrosion at the source, and improving the greenness of operation and equipment adaptability at the same time.

[0061] In addition, to address the problems of large fluctuations in the quality and complex composition of polymer-containing sewage, the overall system adopts an online monitoring and closed-loop control mechanism. Each unit can automatically and collaboratively adjust the chemical dosage, electrolysis intensity, and filtration intensity according to the front-end pollution load to ensure that the system can still operate stably and meet the standards under different pollutant concentrations and pH conditions, and has good adaptability and scalability.

[0062] Finally, to prevent the risks of secondary pollution and system blockage, the present invention configures a by-product monitoring and centralized collection system in the electrolytic oxidation and filtration modules, which can monitor and regularly discharge sludge, oily sludge, electrode corrosion products, foam layers, etc. in real time, and constructs a closed-loop by-product safety management mechanism to improve the environmental protection and stability of system operation.

[0063] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A treatment method for polymer wastewater reinjection, characterized in that: The following steps are involved: Step 1: Pre-treat the polymer-containing wastewater to remove oil and suspended solids; Step 2: performing acid adjustment treatment on the sewage to control its pH value within a range suitable for oxidation treatment; Step 3: injecting gas into the sewage to form a gas-water mixture; Step 4: sending the gas-water mixture into an electrochemical oxidation treatment unit with an automatic cleaning function for electrolytic oxidation treatment, and dynamically adjusting the treatment parameters through a control module; Step 5: Perform alkaline neutralization treatment on the electrolyzed wastewater; Step 6: Perform solid-liquid separation on the neutralized sewage; Step 7: Monitor and manage the emissions of by-products generated during the treatment process.

2. The method according to claim 1, characterized in that The pretreatment includes leaving the polymer-containing wastewater in a sedimentation unit for 10 to 20 hours to remove oil and particulate matter.

3. The method according to claim 1, characterized in that The acid adjustment treatment uses an inorganic acid or an organic acid to adjust the pH value to 3-5.

4. The method according to claim 1, characterized in that: The gas is air, nitrogen, air-ozone or air-hydrogen peroxide.

5. The method according to claim 1, characterized in that The gas is injected through a micro-nano bubble generating device to form bubbles with a particle size of 20 to 80 μm.

6. The method according to claim 1, characterized in that The electrochemical oxidation treatment unit comprises an anode and a cathode of a corrugated structure, and the distance between the electrodes is 3 to 5 cm.

7. The method according to claim 6, characterized in that The anode material includes an iron plate electrode, a boron-doped diamond electrode, a metal oxide-plated electrode, and the like.

8. The method according to claim 1, characterized in that The automatic cleaning function is achieved through a periodic electrode oscillation mechanism.

9. The method according to claim 1, characterized in that: The control module automatically adjusts the current density and electrolysis time according to real-time parameters such as sewage conductivity and pollution load.

10. The method according to claim 1, characterized in that Byproduct monitoring includes online monitoring and automatic emission control of electrode corrosion, foam layer, sludge and suspended particles.

Images