Crude oil storage tank water cutting electrochemical treatment system and operation method thereof

Abstract

The invention provides a crude oil storage tank water cutting electrochemical treatment system and an operation method thereof, and relates to the technical field of crude oil water cutting treatment.The system sequentially comprises an electric flocculation treatment unit and an electrocatalytic oxidation unit according to the treatment sequence of crude oil storage tank water cutting; the electric flocculation treatment unit is used for generating metal hydroxide flocs through anode dissolution, so that suspended solids, colloids, petroleum and COD (Chemical Oxygen Demand) in water are subjected to oxidation, adsorption, flocculation and air flotation separation; and the electrocatalytic oxidation unit is used for degrading petroleum, ammonia nitrogen and COD in water under the action of direct oxidation and indirect oxidation. The technical problems that effluent of a traditional process does not reach the standard and secondary pollution is easily caused are solved, the technical effects that a large number of chemical agents do not need to be added, the treatment cost is low, adaptability is high, meanwhile, water quantity fluctuation and low-temperature operation working conditions can be effectively coped with are achieved, it is guaranteed that storage tank cut water is stably discharged in a standard reaching mode, and enterprise environmental protection risks are eliminated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of crude oil water separation treatment, and particularly relates to a crude oil tank water separation electrochemical treatment system and a running method thereof. BACKGROUND

[0002] In a tank area for storing crude oil, a layer of water is formed at the bottom of the tank area. In order to ensure the quality and safety of the crude oil, the layer of water needs to be separated from the crude oil regularly, which is referred to as crude oil tank water separation. The crude oil tank water separation mainly contains petroleum, demulsifiers, scale inhibitors, corrosion inhibitors, bactericides, defoamers and water treatment agents. In the process of crude oil exploitation, dozens of agents are added, and these agents enter the water during the process of crude oil stabilization, resulting in that the crude oil tank water separation has complex water quality, high pollutant concentration and poor biodegradability, with COD being 1000 mg / L-6000 mg / L, ammonia nitrogen being 30 mg / L-100 mg / L, TDS being 9000 mg / L-20000 mg / L, and chloride ion being 4000 mg / L-10000 mg / L, which is a typical difficult-to-biodegrade toxic and harmful wastewater.

[0003] At present, most crude oil tanks mix the tank water separation with the initial rainwater of the tank area, dilute the tank water separation by using the initial rainwater, and adopt an oil removal plus flotation plus filtration process for treatment. However, when the water quantity of the tank water separation increases or in winter operation, most conventional processes cannot meet the discharge requirements, and a large amount of agents need to be added to cause secondary pollution. If biochemical treatment is adopted, due to the reasons such as intermittent water quantity and poor biodegradability, the biochemical operation conditions cannot be met.

[0004] Therefore, the present application is provided. SUMMARY

[0005] One of the purposes of the present application is to provide a crude oil tank water separation electrochemical treatment system, which solves the technical problems of high pollutant concentration, poor biodegradability, unstable treatment effect of conventional processes, serious secondary pollution and difficult operation of biochemical method in the prior art.

[0006] The second purpose of the present application is to provide a running method of the crude oil tank water separation electrochemical treatment system, which has the advantages of no need to add a large amount of chemical agents, low treatment cost and strong adaptability, can effectively cope with water quantity fluctuation and low temperature operation conditions, is beneficial to ensuring stable and standard discharge of the tank water separation, and eliminates the environmental protection risk of enterprises.

[0007] In order to achieve the above purposes of the present application, the following technical solutions are adopted:

[0008] In a first aspect, a crude oil tank water separation electrochemical treatment system comprises, in the order of treatment of crude oil tank water separation, an electrocoagulation treatment unit and an electrocatalytic oxidation unit.

[0009] The electrocoagulation treatment unit is used to generate metal hydroxide flocs through anodic dissolution, thereby oxidizing, adsorbing, flocculating, and separating suspended solids, colloids, petroleum and COD in water by air flotation.

[0010] The electrocatalytic oxidation unit is used to degrade petroleum hydrocarbons, ammonia nitrogen, and COD in water through direct and indirect oxidation.

[0011] Furthermore, the electrocoagulation treatment unit includes an electrocoagulation reactor;

[0012] Preferably, the electrocoagulation reactor uses a soluble anode;

[0013] Preferably, the soluble anode comprises at least one of an iron electrode and an aluminum electrode;

[0014] Preferably, the cathode of the electrocoagulation reactor includes at least one of a stainless steel electrode, a graphite electrode, and a titanium electrode.

[0015] Preferably, the current in the electrocoagulation reactor is a pulsed current or a direct current with a density of 10 mA / cm³. 2 -50mA / cm 2 .

[0016] Furthermore, the electrocoagulation reactor is provided with at least one of staggered electrode groups and parallel electrode groups;

[0017] Preferably, the electrode spacing of the electrode assembly is 15mm-50mm, and the plane of the electrode is at an angle of 45°-90° to the direction of water flow.

[0018] Furthermore, the electrochemical treatment system also includes a clarification and precipitation unit;

[0019] Preferably, the clarification and precipitation unit is located between the electrocoagulation treatment unit and the electrocatalytic oxidation unit.

[0020] Furthermore, the clarification and sedimentation unit includes at least one of a sedimentation separation unit, a magnetic powder sedimentation separation unit, an air flotation unit, and a filtration unit.

[0021] Furthermore, the electrocatalytic oxidation unit includes an electrocatalytic oxidation reactor;

[0022] Preferably, the anode of the electrocatalytic oxidation reactor includes at least one of the following: ruthenium-iridium coated electrode, iridium-tantalum coated electrode, composite / doped metal oxide electrode, composite / doped lead dioxide electrode, platinum electrode, carbon-based material, and boron-doped diamond electrode.

[0023] Preferably, the cathode of the electrocatalytic oxidation reactor includes at least one of a stainless steel electrode, a graphite electrode, and a titanium electrode.

[0024] Preferably, the current density of the electro-catalytic oxidation reactor is 20mA / cm 2 -100mA / cm 2 .

[0025] Further, at least one of the interleaved electrode plate group, the parallel electrode plate group and the tubular electrode plate group is arranged in the electro-catalytic oxidation reactor.

[0026] Preferably, the electrode plate spacing of the electrode plate group is 15mm-50mm, and the space between the electrode plates is filled with conductive particles.

[0027] In a second aspect, a method for operating the electrochemical treatment system of any one of the above aspects, comprising the following steps:

[0028] The water from the crude oil storage tank is introduced into the electro-flocculation treatment unit for electro-flocculation treatment to obtain the electro-flocculation treated effluent, and the electro-flocculation treated effluent is introduced into the electro-catalytic oxidation unit for electro-catalytic oxidation treatment to obtain the purified effluent.

[0029] Further, the method for operating comprises the following steps:

[0030] The water from the crude oil storage tank is introduced into the electro-flocculation treatment unit for electro-flocculation treatment to obtain the electro-flocculation treated effluent, and the electro-flocculation treated effluent is introduced into the electro-catalytic oxidation unit for electro-catalytic oxidation treatment to obtain the purified effluent.

[0031] Preferably, the current density in the electro-flocculation treatment process is 10mA / cm 2 -50mA / cm 2 ;

[0032] Preferably, the electro-flocculation treatment time is 0.5h-1h.

[0033] Preferably, the current density in the electro-catalytic oxidation treatment process is 20mA / cm 2 -100mA / cm 2 ;

[0034] Preferably, the electro-catalytic oxidation treatment time is 0.5h-2h.

[0035] Further, the COD removal rate of the purified effluent is ≥85%, the petroleum content is ≥70%, the ammonia nitrogen removal rate is ≥50%, and the TDS removal rate is ≥50%.

[0036] Compared with the prior art, the present application has at least the following beneficial effects:

[0037] The crude oil storage tank cut water electrochemical treatment system provided by the application is aimed at the treatment requirements of oil, ammonia nitrogen and COD pollutants in the crude oil storage tank cut water, and the treatment is carried out through an electrocoagulation / electrochemical oxidation coupling process, so that the treatment cost is low, the application is practical and efficient, the crude oil storage tank cut water can be widely applied, and the technical problems of high pollutant concentration, poor biodegradability, unstable treatment effect of conventional process, serious secondary pollution and difficult operation of biochemical method in the prior art are solved.

[0038] The operation method of the crude oil storage tank cut water electrochemical treatment system provided by the application includes an electrocoagulation treatment stage and an electrocatalytic oxidation treatment stage. The electrocoagulation treatment stage removes suspended solids, colloids, part of oil and COD and the like in wastewater through flocculation, flotation, oxidation and reduction mechanisms. The electrocatalytic oxidation treatment stage is mainly an oxidation process, which removes oil, ammonia nitrogen and COD and the like in wastewater through oxidation and reduction mechanisms. In summary, the method of the application does not need to add a large amount of chemical agents, has low treatment cost, strong adaptability, can effectively cope with water fluctuation and low-temperature operation conditions, solves the problems of non-standard effluent and secondary pollution of the traditional process, can ensure stable and standard discharge of the storage tank cut water, and eliminates the environmental protection risk of enterprises. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the specific embodiments of the application or the technical solutions in the prior art, the drawings needed in the specific embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0040] Figure 1 The schematic diagram of the crude oil storage tank cut water electrochemical treatment method provided by one embodiment of the application.

[0041] The figure shows: 1-electrocoagulation treatment unit; 2-clearing and sedimentation unit; 3-electrocatalytic oxidation unit; 4-power supply; 5-positive electrode of power supply; 6-negative electrode of power supply; 7-raw water inlet pipe; 8-electrocoagulation anode plate; 9-electrocoagulation cathode plate; 10-electrocoagulation treatment unit effluent pipe; 11-electrocatalytic oxidation unit inlet pipe; 12-electrocatalytic oxidation anode plate; 13-electrocatalytic oxidation cathode plate; 14-electrocatalytic oxidation unit effluent pipe. DETAILED DESCRIPTION

[0042] The technical solutions of the application will be described below in conjunction with the embodiments. Obviously, the described embodiments are some of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0043] According to a first aspect of the present application, there is provided a crude oil tank cutting water electrochemical treatment system, which comprises, in sequence according to the treatment order of the crude oil tank cutting water, an electrocoagulation treatment unit and an electrocatalytic oxidation unit.

[0044] The electrocoagulation treatment unit is used to generate metal hydroxide flocs through anode dissolution, so as to oxidize, adsorb, flocculate and float separate the suspended solids, colloids, petroleum and COD in the water.

[0045] The electrocatalytic oxidation unit is used to degrade the petroleum, ammonia nitrogen and COD in the water through the effects of direct oxidation and indirect oxidation.

[0046] In view of the treatment requirements of the pollutants such as petroleum, ammonia nitrogen and COD in the crude oil tank cutting water, the system of the present application is treated by the electrocoagulation / electrochemical oxidation coupling process, which not only has low treatment cost, but also is practical and efficient, and can be widely applied to treat the crude oil tank cutting water, and solves the technical problems of high pollutant concentration, poor biodegradability, unstable treatment effect of conventional process, serious secondary pollution and difficult operation of biochemical method in the prior art.

[0047] In the present application, the electrocoagulation treatment unit includes but is not limited to an electrocoagulation reactor.

[0048] In a preferred embodiment, the electrocoagulation reactor adopts a soluble anode, which includes but is not limited to at least one of an iron electrode (i.e. iron plate) and an aluminum electrode (i.e. aluminum plate), and is more conducive to generating metal hydroxide flocs through anode dissolution; the cathode of the electrocoagulation reactor includes but is not limited to at least one of a stainless steel electrode, a graphite electrode and a titanium electrode.

[0049] In a preferred embodiment, the current of the electrocoagulation reactor can be pulse current or direct current, and the density can be 10mA / cm 2 - 50mA / cm 2 , for example, typical but not limited current density is 10mA / cm 2 , 20mA / cm 2 , 30mA / cm 2 , 40mA / cm 2 , 50mA / cm 2 , which is more conducive to improving the electrocoagulation effect.

[0050] In the present application, the electric flocculation reactor can be provided with staggered electrode plate groups and / or parallel electrode plate groups; meanwhile, the electrode plate spacing of the electrode plate groups can be 15-50 mm, for example, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, but not limited to this; the electrode plate plane can form an angle of 45-90° with the water flow direction.

[0051] In a preferred embodiment, the electrochemical treatment system further comprises but is not limited to a clarification sedimentation unit, which can be arranged between the electric flocculation treatment unit and the electro-catalytic oxidation unit.

[0052] In a preferred embodiment, the clarification sedimentation unit comprises but is not limited to at least one of a sedimentation separation unit, a magnetic powder precipitation separation unit, a gas floatation unit, and a filtration unit.

[0053] In the present application, the electro-catalytic oxidation unit comprises but is not limited to an electro-catalytic oxidation reactor.

[0054] In a preferred embodiment, the anode of the electro-catalytic oxidation reactor can adopt a titanium-based noble metal coating electrode, which comprises but is not limited to at least one of a ruthenium-iridium coating electrode, an iridium-tantalum coating electrode, a composite / doped metal oxide electrode, a composite / doped lead dioxide electrode, a platinum electrode, a carbon-based material, and a boron-doped diamond electrode; the cathode of the electro-catalytic oxidation reactor comprises but is not limited to at least one of a stainless steel plate electrode, a graphite plate electrode, and a porous titanium mesh electrode.

[0055] In a preferred embodiment, the current density of the electro-catalytic oxidation reactor can be 20 mA / cm 2 -100 mA / cm 2 , for example, a typical but non-limiting current density is 20 mA / cm 2 , 30 mA / cm 2 , 40 mA / cm 2 , 50 mA / cm 2 , 60 mA / cm 2 , 70 mA / cm 2 , 80 mA / cm 2 , 90 mA / cm 2 , 100 mA / cm 2 , which is more conducive to improving the electro-catalytic oxidation effect.

[0056] In the present application, at least one of the staggered electrode plate group, the parallel electrode plate group and the tubular electrode plate group can be arranged in the electro-catalytic oxidation reactor; meanwhile, the electrode plate spacing of the electrode plate group can be 15-50 mm, for example, can be 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm or 50 mm, but is not limited thereto; in addition, the electrode plate spacing can be filled with conductive particles (such as activated carbon, metal oxide loaded particles) to form a three-dimensional reinforced electrode structure.

[0057] According to a second aspect of the present application, a method for operating the electrochemical treatment system of any one of the above is provided, comprising the following steps:

[0058] The crude oil tank cut water is introduced into the electro-flocculation treatment unit for electro-flocculation treatment to obtain electro-flocculation treated effluent, and the electro-flocculation treated effluent is introduced into the electro-catalytic oxidation unit for electro-catalytic oxidation treatment to obtain purified effluent.

[0059] The method of the present application comprises an electro-flocculation treatment stage and an electro-catalytic oxidation treatment stage. The electro-flocculation treatment stage removes suspended solids, colloids, part of oil and COD in the wastewater through flocculation, flotation, oxidation and reduction mechanisms. The electro-catalytic oxidation treatment stage is mainly an oxidation process, which removes oil, ammonia nitrogen and COD in the wastewater through oxidation and reduction mechanisms. In summary, the method of the present application does not need to add a large amount of chemical agents, has low treatment cost and strong adaptability, can effectively cope with water fluctuation and low temperature operation conditions, solves the problems of non-compliance of the effluent of the traditional process and secondary pollution, and can ensure stable and compliant discharge of the tank cut water and eliminate the environmental protection risk of the enterprise.

[0060] It should be noted that, according to different treatment requirements of the crude oil tank cut water, the process flow of the method of the present application can be applied in sections or repeatedly applied in multiple sections, that is, the electro-flocculation treatment stage and the electro-catalytic oxidation treatment stage can be independently applied, or some or several treatment stages can be repeatedly applied. The process is flexible and efficient, can be adjusted according to the discharge requirements, has good treatment effect, the treatment effect is not affected by water quality fluctuation, seasonal change and the like, has high impact load resistance, does not need to add additional chemical agents, has small sludge production, and no secondary pollutants are generated.

[0061] In a preferred embodiment, the method for operating the present application comprises the following steps:

[0062] The crude oil tank cut water is introduced into the electro-flocculation treatment unit for electro-flocculation treatment to obtain electro-flocculation treated effluent, the electro-flocculation treated effluent is introduced into the clarification and precipitation unit for clarification treatment to obtain clarified effluent, and the clarified effluent is introduced into the electro-catalytic oxidation unit for electro-catalytic oxidation treatment to obtain purified effluent.

[0063] The current density in the electrocoagulation treatment process can be 10 mA / cm 2 - 50 mA / cm 2 The electrocoagulation treatment time can be 0.5 h-1 h.

[0064] The current density in the electro-catalytic oxidation treatment process can be 20 mA / cm 2 - 100 mA / cm 2 The electro-catalytic oxidation treatment time can be 0.5 h-2 h.

[0065] A typical method for electrochemical treatment of water cutting of a crude oil storage tank is shown in Figure 1 , comprising the following steps:

[0066] The crude oil storage tank water cutting enters the electrocoagulation treatment unit 1 through the raw water inlet pipe 7, and is subjected to electrocoagulation treatment under the action of the power supply 4 (current density 15 mA / cm 2 - 50 mA / cm 2 ), wherein the electrodes are arranged in parallel with a spacing of 15 mm-50 mm, the electrocoagulation anode plate 8 uses an aluminum electrode or an iron electrode, the electrocoagulation cathode plate 9 uses a stainless steel or graphite or titanium electrode, the electrocoagulation treatment has a wastewater residence time of 0.5 h-1 h, and the electrocoagulation treated storage tank water cutting is obtained.

[0067] The electrocoagulation treated storage tank water cutting enters the clarification sedimentation unit 2 through the electrocoagulation treatment unit outlet pipe 10 for clarification treatment, and the clarified wastewater enters the electro-catalytic oxidation unit 3 through the electro-catalytic oxidation unit inlet pipe 11, and is subjected to electro-catalytic oxidation treatment under the action of the power supply 4 (current density 20 mA / cm 2 - 50 mA / cm 2 ), wherein the electrodes are arranged in parallel with a spacing of 15 mm-50 mm, the electro-catalytic oxidation anode plate 12 uses a ruthenium-iridium coated electrode or a BDD electrode, the electro-catalytic oxidation cathode plate 13 uses a stainless steel or graphite electrode, the electro-catalytic oxidation treatment temperature is 25℃-45℃, the wastewater residence time is 0.5 h-2 h, the electro-catalytic oxidation unit outlet pipe 14 discharges water, and the electro-catalytic oxidation treated storage tank water cutting is obtained as the purified outlet water.

[0068] In the present application, the COD removal rate of the purified outlet water is ≥85%, the petroleum content is ≥70%, the ammonia nitrogen removal rate is ≥50%, and the TDS removal rate is ≥50%.

[0069] The present application will be further described by examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.

[0070] Example 1

[0071] The application discloses an electrochemical treatment system for water cutting of a crude oil storage tank.

[0072] The electrocoagulation treatment unit is used for generating metal hydroxide flocs through anode dissolution, so as to oxidize, adsorb, flocculate and air float separate suspended solids, colloids, petroleum and COD in water.

[0073] The electrocoagulation treatment unit comprises an electrocoagulation reactor, the soluble anode is an iron electrode, and the cathode of the electrocoagulation reactor is made of a 316L stainless steel plate.

[0074] The electro-catalytic oxidation unit is used for degrading petroleum, ammonia nitrogen and COD in water through direct oxidation and indirect oxidation.

[0075] The electro-catalytic oxidation unit comprises an electro-catalytic oxidation reactor, the anode of the electro-catalytic oxidation reactor is a Ti / RuO-IrO electrode, and the cathode of the electro-catalytic oxidation reactor is made of a 316L stainless steel plate.

[0076] Embodiment 2

[0077] The embodiment provides an electrochemical treatment system for water cutting of a crude oil storage tank, which is different from the embodiment 1 only in that the electrochemical treatment system further comprises a clarification and precipitation unit.

[0078] The clarification and precipitation unit is arranged between the electrocoagulation treatment unit and the electro-catalytic oxidation unit.

[0079] The clarification and precipitation unit comprises at least one of a sedimentation separation unit, a magnetic powder precipitation separation unit, an air floatation unit and a filtration unit.

[0080] The rest is the same as the embodiment 1.

[0081] Embodiment 3

[0082] The embodiment is a running method of the electrochemical treatment system for water cutting of a crude oil storage tank in the embodiment 2, which comprises the following steps.

[0083] The water cutting of the crude oil storage tank is first subjected to mesh filtration (mesh size 5mm-10mm) to remove part of suspended solids, and then enters the electrocoagulation treatment unit to be subjected to electrocoagulation treatment, the current density adopted in the electrocoagulation treatment is 30mA / cm 2 , the electrocoagulation treatment time is 0.5h, the electrode plate spacing of the electrode plate group in the electrocoagulation treatment is 20mm, and the water cutting of the crude oil storage tank after the electrocoagulation treatment is obtained.

[0084] The crude oil tank cut water quality: suspended solids 30 mg / L, COD 510.61 mg / L, ammonia nitrogen 17.22 mg / L, chloride ion 2953 mg / L, polymer 245.00 mg / L, and petroleum 1.36 mg / L;

[0085] The crude oil tank cut water after the electrocoagulation treatment enters a clarification and precipitation unit for clarification treatment, and the clarified crude oil tank cut water is obtained.

[0086] The clarified crude oil tank cut water enters an electrocatalytic oxidation unit for electrocatalytic oxidation treatment, the electrocatalytic oxidation treatment uses a current density of 40 mA / cm 2 , the electrocatalytic oxidation treatment time is 45 min, the electrode plate spacing of the electrode plate group of the electrocatalytic oxidation treatment is 20 mm, and the electrocatalytic oxidation treated crude oil tank cut water is obtained, which is the final effluent.

[0087] The final effluent quality obtained in the embodiment: suspended solids 5 mg / L, COD 40 mg / L, ammonia nitrogen 4 mg / L, chloride ion 2590 mg / L, polymer 5.00 mg / L, and petroleum 0.5 mg / L.

[0088] Example 4

[0089] The embodiment is a running method of the crude oil tank cut water electrochemical treatment system of Example 2, comprising the following steps:

[0090] The crude oil tank cut water is first filtered through a grid (grid size 5 mm-10 mm) to remove part of the suspended solids, and then enters an electrocoagulation treatment unit for electrocoagulation treatment, the electrocoagulation treatment uses a current density of 30 mA / cm 2 , the electrocoagulation treatment time is 40 min, and the electrode plate spacing of the electrode plate group of the electrocoagulation treatment is 25 mm, and the electrocoagulation treated crude oil tank cut water is obtained.

[0091] The crude oil tank cut water quality: suspended solids 254 mg / L, COD 1270 mg / L, ammonia nitrogen 16.22 mg / L, chloride ion 3315 mg / L, polymer 453.00 mg / L, and petroleum 96.75 mg / L;

[0092] The crude oil tank cut water after the electrocoagulation treatment enters a clarification and precipitation unit for clarification treatment, and the clarified crude oil tank cut water is obtained.

[0093] The clarified crude oil tank cut water enters an electrocatalytic oxidation unit for electrocatalytic oxidation treatment, the electrocatalytic oxidation treatment uses a current density of 50 mA / cm 2 , the electrocatalytic oxidation treatment time is 1 h, the electrode plate spacing of the electrode plate group of the electrocatalytic oxidation treatment is 25 mm, and the electrocatalytic oxidation treated crude oil tank cut water is obtained, which is the final effluent.

[0094] The final effluent water quality obtained in this embodiment: suspended solids 5 mg / L, COD 50 mg / L, ammonia nitrogen 3.2 mg / L, chloride 3150 mg / L, polymer 25.00 mg / L, and petroleum 1.0 mg / L.

[0095] Comparative Example 1

[0096] The only difference between this comparative example and Example 1 is that no electrocoagulation treatment unit is provided.

[0097] The rest is the same as Example 1.

[0098] Compared with Example 1, the defect of this comparative example is that, since metal hydroxide floc cannot be generated, oxidation, adsorption, flocculation and air floatation separation of suspended solids, colloids, petroleum and COD in water cannot be performed.

[0099] Comparative Example 2

[0100] The only difference between this comparative example and Example 1 is that no electro-catalytic oxidation unit is provided.

[0101] The rest is the same as Example 1.

[0102] Compared with Example 1, the defect of this comparative example is that petroleum, ammonia nitrogen and COD in water cannot be degraded by direct oxidation and indirect oxidation.

[0103] In summary, the method of the present application does not need to add a large amount of chemical agents, has low treatment cost and strong adaptability, can effectively deal with water fluctuation and low temperature operation conditions, solves the problems of non-standard effluent and secondary pollution of traditional processes, can ensure stable and standard discharge of tank water, and eliminates environmental protection risks of enterprises.

[0104] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A crude oil storage tank water electrochemical treatment system, characterized in that, According to the treatment sequence of water removal from crude oil storage tanks, it includes an electrocoagulation treatment unit and an electrocatalytic oxidation unit in sequence; The electrocoagulation treatment unit is used to generate metal hydroxide flocs through anodic dissolution, thereby oxidizing, adsorbing, flocculating, and separating suspended solids, colloids, petroleum and COD in water by air flotation. The electrocatalytic oxidation unit is used to degrade petroleum hydrocarbons, ammonia nitrogen, and COD in water through direct and indirect oxidation.

2. The electrochemical treatment system according to claim 1, characterized in that, The electrocoagulation treatment unit includes an electrocoagulation reactor; Preferably, the electrocoagulation reactor uses a soluble anode; Preferably, the soluble anode comprises at least one of an iron electrode and an aluminum electrode; Preferably, the cathode of the electrocoagulation reactor includes at least one of a stainless steel electrode, a graphite electrode, and a titanium electrode. Preferably, the current in the electrocoagulation reactor is a pulsed current or a direct current with a density of 10 mA / cm³. 2 -50mA / cm 2 .

3. The electrochemical treatment system according to claim 2, characterized in that, The electrocoagulation reactor is provided with at least one of staggered electrode groups and parallel electrode groups. Preferably, the electrode spacing of the electrode assembly is 15mm-50mm, and the plane of the electrode is at an angle of 45°-90° to the direction of water flow.

4. The electrochemical treatment system according to claim 1, characterized in that, The electrochemical treatment system also includes a clarification and precipitation unit; Preferably, the clarification and precipitation unit is located between the electrocoagulation treatment unit and the electrocatalytic oxidation unit.

5. The electrochemical treatment system according to claim 4, characterized in that, The clarification and sedimentation unit includes at least one of a sedimentation separation unit, a magnetic powder sedimentation separation unit, an air flotation unit, and a filtration unit.

6. The electrochemical treatment system according to claim 1, characterized in that, The electrocatalytic oxidation unit includes an electrocatalytic oxidation reactor; Preferably, the anode of the electrocatalytic oxidation reactor includes at least one of the following: ruthenium-iridium coated electrode, iridium-tantalum coated electrode, composite / doped metal oxide electrode, composite / doped lead dioxide electrode, platinum electrode, carbon-based material, and boron-doped diamond electrode. Preferably, the cathode of the electrocatalytic oxidation reactor includes at least one of a stainless steel electrode, a graphite electrode, and a titanium electrode. Preferably, the current density of the electrocatalytic oxidation reactor is 20 mA / cm². 2 -100mA / cm 2 .

7. The electrochemical treatment system according to claim 6, characterized in that, The electrocatalytic oxidation reactor is provided with at least one of the following: staggered electrode group, parallel electrode group, and tubular electrode group. Preferably, the electrode spacing of the electrode assembly is 15mm-50mm, and the space between the electrodes is filled with conductive particles.

8. A method for operating the electrochemical treatment system according to any one of claims 1-7, characterized in that, Includes the following steps: The water from the crude oil storage tank is fed into the electrocoagulation treatment unit for electrocoagulation treatment to obtain electrocoagulated effluent. The electrocoagulated effluent is then fed into the electrocatalytic oxidation unit for electrocatalytic oxidation treatment to obtain purified effluent.

9. The operating method according to claim 8, characterized in that, The operating method includes the following steps: The water from the crude oil storage tank is fed into the electrocoagulation treatment unit for electrocoagulation treatment to obtain electrocoagulated effluent. The electrocoagulated effluent is then fed into the clarification and sedimentation unit for clarification treatment to obtain clarified effluent. The clarified effluent is then fed into the electrocatalytic oxidation unit for electrocatalytic oxidation treatment to obtain purified effluent. Preferably, the current density during the electrocoagulation process is 10 mA / cm². 2 -50mA / cm 2 ; Preferably, the electrocoagulation treatment time is 0.5h-1h; Preferably, the current density during the electrocatalytic oxidation process is 20 mA / cm². 2 -100mA / cm 2 ; Preferably, the electrocatalytic oxidation treatment time is 0.5h-2h.

10. The operating method according to claim 9, characterized in that, The purified effluent has a COD removal rate of ≥85%, a petroleum content of ≥70%, an ammonia nitrogen removal rate of ≥50%, and a TDS removal rate of ≥50%.

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