Novel electric flocculation and air floatation integrated device for oil and gas field wastewater treatment

Abstract

The utility model relates to the technical field of oil and gas field wastewater treatment, in particular to a novel electric flocculation and air floatation integrated device for oil and gas field wastewater treatment, which comprises a tank body, an electric flocculation and air floatation tank and a flocculation settling tank, a floating oil recovery scraper is mounted at the top of the electric flocculation air floatation tank, an oil collection tank is separated in the electric flocculation air floatation tank, and the floating oil recovery scraper is communicated with the oil collection tank. According to the device, the electrolytic flocculation equipment, the air floatation equipment and the sedimentation equipment are arranged to be an upper and lower split combined device, the three-in-one effect is achieved, the equipment structure is more reasonable, the treatment efficiency can be improved, meanwhile, the occupied area is reduced, the capital construction investment is saved, and the cost is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to oil and gas field wastewater treatment technical field especially is a kind of new oil and gas field wastewater treatment electric flocculation air floatation integrated device. BACKGROUND

[0002] Oil and gas field wastewater mainly refers to oil and gas field fracturing flowback fluid, oil and gas field produced water, mud filtrate and other wastewater.At present, most of the oil and gas field wastewater treatment stations use the wastewater treatment process of "natural oil removal + air floatation equipment + pre-oxidation device + coagulation sedimentation + pressure filtration", and the oil content in wastewater is separated from water mainly through the oil recovery tank with storage function, and then the sewage enters the small square air floatation equipment, and after being treated by the air floatation equipment, the sewage enters the pre-oxidation device to oxidize the low-valence harmful ions in the sewage, so as to remove the crude oil in the sewage and convert the harmful low-valence ions into high-valence ions conducive to flocculation, and then the sewage treated by the coagulation sedimentation and filtration device reaches the water injection standard.With the increase of the workload of oil and gas field stimulation measures and the application of a large amount of chemical oil displacement agent, the oil-water separation of oil and gas field waste liquid becomes more and more difficult, which often causes the increase of oil content in the produced water;there are various additives in the wastewater, and it is difficult to reduce the COD value, especially some hydrophilic organic additives that are not easy to remove from the wastewater;the water-based mud filtrate contains COD, suspended solids (SS), sulfide, calcium ions and magnesium ions, and the pollution factors and harmful ions are not easy to remove from the wastewater, so the natural oil removal by the oil recovery tank, the conventional air floatation device and the conventional pre-oxidation device cannot meet the control requirements of the oil content, organic additives, pollution factors and harmful ions in the wastewater, which brings many difficulties to the subsequent wastewater treatment.

[0003] The existing technical problems are: (1) the natural oil removal and the conventional air floatation device have low oil removal rate in raw water, causing resource waste; (2) the rear-end air floatation equipment and the pre-oxidation device have no flocculation sedimentation effect, so that part of the crude oil, harmful ions and suspended solids flocculation enter the filter, causing secondary pollution to the filter material and water quality; (3) the air floatation equipment, the pre-oxidation equipment and the coagulation sedimentation device are separately arranged, causing large equipment investment, repeated operation of workers, and increase of land occupation area and capital construction investment cost; (4) a large amount of iron and aluminum chemical agents are used in the oil and gas field wastewater treatment, and the iron and aluminum flocculation ions are decomposed from the electrode plate of the electric flocculation air floatation device, which is beneficial to flocculation and saves water treatment agents. UTILITY MODEL CONTENT

[0004] In order to overcome the above-mentioned existing technical defects, the utility model provides the following technical solutions.

[0005] The utility model provides a novel electric flocculation air flotation integrated device for oil and gas field wastewater treatment, which comprises a tank body, which is divided into an electric flocculation air flotation tank and a flocculation sedimentation tank stacked in an upper-lower manner, wherein the electric flocculation air flotation tank is located at the upper layer, and the flocculation sedimentation tank is located at the lower layer; a floating oil recovery scraper is mounted at the top of the electric flocculation air flotation tank; and an oil collection tank is arranged in the electric flocculation air flotation tank and is in communication with the floating oil recovery scraper.

[0006] Further, the electric flocculation air flotation tank comprises an electrode buffer zone, a first electrode plate catalytic oxidation zone and a second electrode plate catalytic oxidation zone, which are separated from each other by partitioning plates.

[0007] Further, the flocculation sedimentation tank comprises a mixing zone, a sedimentation zone and a buffer zone, which are separated from each other by partitioning plates.

[0008] Further, a water inlet of the electric flocculation air flotation tank is arranged on the outer wall of the side where the electrode buffer zone is located; a water outlet of the electric flocculation air flotation tank is arranged on the outer wall of the side where the second electrode plate catalytic oxidation zone is located; a water inlet of the flocculation sedimentation tank is arranged on the outer wall of the side where the mixing zone is located; a water outlet of the flocculation sedimentation tank is arranged on the outer wall of the side where the buffer zone is located; and the water outlet of the electric flocculation air flotation tank and the water inlet of the flocculation sedimentation tank are in communication through a vertically arranged pipeline.

[0009] Further, the second electrode plate catalytic oxidation zone is provided with a valve plate controlled water outlet, which is connected with the water outlet of the electric flocculation air flotation tank.

[0010] Further, an overflow port is arranged at the upper part of the electric flocculation air flotation tank.

[0011] Further, a sewage discharge port is arranged at the bottom of each partition of the electric flocculation air flotation tank and the flocculation sedimentation tank.

[0012] The utility model has the beneficial technical effects that:

[0013] 1. The upper-lower split combination type device allows electrolysis, air flotation and flocculation to be carried out in independent spaces, and the device structure is rationalized, so that the treatment efficiency can be improved; compared with conventional natural oil removal devices and simple air flotation devices, the oil recovery rate of the wastewater can be obviously improved, the crude oil recovery rate can be improved by about 40%, and resource waste can be reduced.

[0014] 2. The connection between the electrolysis electrode plates effectively reduces the spacing between the electrode plates, so that the tank voltage and energy consumption can be reduced; compared with the traditional device, the energy consumption per ton of water can be reduced by about 45%; through the electrode reaction, complex compounds and hydroxides with flocculation effect can be generated, so that colloidal impurities and suspended impurities in the wastewater can be coagulated and separated in the sedimentation zone; at the same time, the charged pollutant particles swim in the electric field, part of the electric charge is neutralized by the electrode, so that the particles are destabilized and gathered and separated to be settled, the addition of chemical agents can be saved, the disposal cost can be reduced, and the use cost of the chemical agents can be reduced by about 30%.

[0015] 3、The device sets electrolytic flocculation, air flotation and sedimentation equipment as an upper and lower split combination device, plays a three-in-one role, can save equipment capital investment and reduce floor area, save capital construction investment, and the investment cost can be reduced by 50%; it is more beneficial to sewage treatment of the rear-end process, is beneficial to stable water quality reaching the standard, can greatly reduce the content of crude oil and organic chemical additives in sludge, finally realizes harmless disposal and resource utilization of sludge residues, meets the green environmental protection requirement, produces good social benefits, can reduce the amount of hazardous waste, and reduces the hazardous waste disposal cost. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is an overall structural schematic view of the integrated device of the utility model.

[0017] In the figure, the specific names of the components are marked as follows:

[0018] 1 - water inlet, 2 - floating oil recovery scraper, 3 - oil collection tank, 4 - electrode buffer zone, 5 - first-stage electrode plate catalytic oxidation zone, 6 - second-stage electrode plate catalytic oxidation zone, 7 - valve plate control water outlet, 8 - electrocoagulation air flotation tank water outlet, 9 - flocculation sedimentation tank water inlet 9, 10 - mixing zone, 11 - sedimentation zone, 12 - buffer zone, 13 - partition plate, 14 - flocculation sedimentation tank water outlet, 15 - overflow port, 16 - blowdown port, 17 - tank body. DETAILED DESCRIPTION

[0019] In order to make the structure, principle and technical characteristics of the utility model easy to understand, the utility model of a novel oil and gas field wastewater treatment electrocoagulation air flotation integrated device is further described in detail below with reference to the drawings, but should not be regarded as limiting the utility model.

[0020] Referring to Figure 1 The utility model sets up an electrocoagulation air flotation integrated device by air flotation device, pre-oxidation device and coagulation sedimentation device, including tank body 17, the top is electrocoagulation air flotation tank, the bottom is flocculation sedimentation tank, the electrocoagulation air flotation tank includes electrode buffer zone 4, first-stage electrode plate catalytic oxidation zone 5 and second-stage electrode plate catalytic oxidation zone 6, and is separated by partition plate 13. The flocculation sedimentation tank includes mixing zone 10, sedimentation zone 11 and buffer zone 12, and is separated by partition plate 13. The top of the electrocoagulation air flotation tank is provided with floating oil recovery scraper 2, and is internally separated by oil collection tank 3. Floating oil recovery scraper 2 includes tensioning device and carbon steel chain, and N = 0.55Kw, the running speed is 3m / min.

[0021] Oil and gas field wastewater enters the electrode buffer zone 4 through the inlet pipeline of inlet 1. A partition plate 13 separates the buffer mixing zone 4 from the primary electrode plate catalytic oxidation zone 5. The wastewater enters the primary electrode plate catalytic oxidation zone 5 from the buffer mixing zone 4, where it undergoes the first-stage electrode reaction, producing compounds that facilitate flocculation and purification, while simultaneously generating electrolytic bubbles for flotation and oil removal. The wastewater then enters the secondary electrode plate catalytic oxidation zone 6 from the upper part of the primary electrode plate catalytic oxidation zone 5, where it undergoes further electrode catalytic oxidation reactions, reacting with impurities and ions in the wastewater to form flocs. The reacted wastewater then enters the mixing zone 10 through the outlet 7 controlled by the valve plate and the inlet 9 of the settling tank. The floating oil is fed into the oil collection tank 3 via the floating oil recovery scraper 2 for crude oil recovery; the sludge generated by the electrocoagulation flotation tank is discharged through the drain outlet 16 and enters the sludge thickening system; the wastewater enters the mixing zone 10, a small amount of flocculant is added, and after mixing and flocculation reaction, it enters the settling zone 11, where the settling and separation process is completed. The supernatant enters the buffer zone 12, and the sludge is discharged through the drain outlet 16 and enters the sludge thickening system; when the liquid level is high, a warning overflow outlet 15 is set up, and the wastewater exceeding the liquid level enters the sewage tank through the overflow outlet 15; the purified water in the buffer zone 12 enters the downstream fine filtration system through the flocculation settling tank outlet 14 for further deep treatment.

[0022] The specific reaction principle is as follows: The electrocoagulation reaction uses aluminum and iron as anodes. Under the action of direct current, the sacrificial anode produces aluminum and iron ions. Then, through a series of hydrolysis, polymerization, and ferrous oxidation processes, complexes and hydroxides with flocculation effects are produced, causing colloidal and suspended impurities in the wastewater to coagulate and separate in the settling zone. At the same time, charged pollutant particles migrate in the electric field, and some of their charge is neutralized by the electrodes, causing them to destabilize and accumulate in the settling zone for separation and sedimentation. Meanwhile, bubbles are generated during the electrode electrolysis process, which can play a role in air flotation for oil removal, which is conducive to the aggregation and floating of oil in the water, thus separating oil and water and achieving the effect of oil removal.

[0023] The above description, in conjunction with specific embodiments, provides a further detailed explanation of this application and should not be construed as limiting the specific implementation of this application to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of this application, and all such modifications or substitutions should be considered within the scope of protection of this application.

Claims

1. A novel electric flocculation air flotation integrated device for oil and gas field wastewater treatment, characterized in that: The tank body (17) is divided into an electric flocculation air flotation tank and a flocculation sedimentation tank stacked in upper and lower layers, wherein the electric flocculation air flotation tank is located in the upper layer, the flocculation sedimentation tank is located in the lower layer, a floating oil recovery scraper (2) is installed at the top of the electric flocculation air flotation tank, and an oil collection tank (3) is internally partitioned, and the floating oil recovery scraper (2) is communicated with the oil collection tank (3).

2. The new electric flocculation air flotation integrated device for oil and gas field wastewater treatment according to claim 1, characterized in that: The electric flocculation air flotation tank comprises an electrode buffer zone (4), a primary electrode plate catalytic oxidation zone (5) and a secondary electrode plate catalytic oxidation zone (6), and partitioning partitions (13) are arranged between the zones.

3. The new type of integrated electric flocculation air flotation device for oil and gas field wastewater treatment according to claim 2, characterized in that: The flocculation sedimentation tank comprises a mixing zone (10), a sedimentation zone (11) and a buffer zone (12), and partitioning partitions (13) are arranged between the zones.

4. The new type of integrated electric flocculation air flotation device for oil and gas field wastewater treatment according to claim 3, characterized in that: An electric flocculation air flotation tank water inlet (1) is arranged on the outer wall of the side where the electrode buffer zone (4) is located, a secondary electrode plate catalytic oxidation zone (6) water outlet (8) is arranged on the outer wall of the side where the secondary electrode plate catalytic oxidation zone (6) is located, a flocculation sedimentation tank water inlet (9) is arranged on the outer wall of the side where the mixing zone (10) is located, a flocculation sedimentation tank water outlet (14) is arranged on the outer wall of the side where the buffer zone (12) is located, and the electric flocculation air flotation tank water outlet (8) and the flocculation sedimentation tank water inlet (9) are communicated through a vertically arranged pipeline.

5. The new type of integrated electric flocculation air flotation device for oil and gas field wastewater treatment according to claim 4, characterized in that: The secondary electrode plate catalytic oxidation zone (6) is provided with a valve plate controlled water outlet (7), and the valve plate controlled water outlet (7) is connected with the electric flocculation air flotation tank water outlet (8).

6. The new type of integrated electric flocculation air flotation device for oil and gas field wastewater treatment according to claim 5, characterized in that: An overflow port (15) is arranged at the upper part of the electric flocculation air flotation tank.

7. The integrated electrocoagulation and dissolved air flotation device for oil and gas field wastewater treatment according to any one of claims 1-6, characterized in that: A sewage discharge port (16) is arranged at the bottom of each partition of the electric flocculation air flotation tank and the flocculation sedimentation tank.

Images