A low-temperature plasma stirring device for treating oilfield drilling wastewater

Abstract

The present invention relates to the technical field of wastewater treatment, and in particular to a low-temperature plasma stirring device for treating oilfield drilling wastewater. The device comprises a stirring shaft and a stirring impeller, wherein one end of the stirring shaft is blocked, and the other end is connected to an inner cavity to form an air inlet. The stirring shaft is provided with a plurality of groups of air outlet holes along its axial direction, the apertures of each group of air outlet holes are different, and a crushing impeller is provided at a portion of the stirring shaft corresponding to the large-diameter air outlet holes, and a spoiler is installed along its axial direction. The present invention introduces a low-temperature plasma external field, and can treat drilling wastewater through various methods such as high-energy electron radiation, oxidation of active particles such as free radicals, and ultraviolet decomposition, thereby improving treatment efficiency while reducing the demand for chemical catalysts, thereby reducing not only capital costs but also environmental pollution. In addition, the stirring impeller and the spoiler are used to significantly improve the liquid-solid mixing in the stirring tank, improve reaction efficiency, and make wastewater treatment more thorough.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, in particular to a low-temperature plasma stirring device for treating oilfield drilling wastewater. Background Art

[0002] During oil and gas field extraction and drilling processes, drilling wastewater is generated, containing large amounts of oil, solid particles, heavy metal ions, and various additives. Due to its complex composition and highly polluting properties, drilling wastewater is difficult to treat and can easily cause serious environmental pollution. The use of mixing tanks plays a crucial role in current drilling wastewater treatment technologies, enabling more thorough wastewater mixing and chemical treatment, improving the efficiency and effectiveness of drilling wastewater treatment. Traditional wastewater treatment typically involves the use of catalysts in mixing tanks. However, this approach, due to the large amount of chemicals used, increases the production of byproducts and is prone to uneven mixing and particle sedimentation of catalyst particles, resulting in uneven reactant concentrations and reduced reaction efficiency. Furthermore, there are challenges such as prolonged reaction times and the inability to react in certain areas. Furthermore, traditional mixing tanks require higher power levels to treat highly concentrated or viscous wastewater, significantly increasing treatment costs.

[0003] Low-temperature plasma technology treats drilling wastewater by utilizing the synergistic effects of multiple methods, including high-energy electrons, ions, atoms, and free radicals present in the plasma, ozone oxidation, and ultraviolet light decomposition. First, the discharge of low-temperature plasma can generate a large number of high-energy electrons, which directly act on pollutants in the wastewater; second, the ionization process of low-temperature plasma produces a large amount of strong oxidants such as ozone and hydrogen peroxide, which promote the chemical reaction of harmful substances and reduce the content of harmful substances in drilling wastewater; in addition, the electrolysis of low-temperature plasma also produces ultraviolet rays, which can decompose harmful substances alone or in combination with ozone. Based on the effectiveness and safety of this technology, low-temperature plasma technology can be combined with the action of a stirring tank to ensure that the various active substances generated by the low-temperature plasma discharge fully treat the drilling wastewater under the uniform mixing action of the stirring tank, thereby maximizing the removal of harmful substances. Based on this idea, the present invention has designed a low-temperature plasma stirring device for treating oilfield drilling wastewater. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: in order to overcome the problems that catalysts are usually used in stirring tanks during traditional wastewater treatment, a large amount of chemical agents are used, the production of by-products is increased, and phenomena such as uneven mixing of catalyst particles and particle deposition are prone to occur, resulting in uneven reactant concentrations and reduced reaction efficiency. A low-temperature plasma stirring device for oilfield drilling wastewater treatment is now provided.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a low-temperature plasma stirring device for treating oilfield drilling wastewater, comprising a stirring shaft with an inner cavity and a stirring impeller fixed at the bottom of the stirring shaft;

[0006] One end of the stirring shaft along its axial direction is blocked, and the other end is connected to the inner cavity to form an air inlet for plasma to enter, and the stirring shaft is provided with a plurality of groups of air outlet holes along its axial direction that are connected to the inner cavity for plasma in the inner cavity to flow out, the aperture of each group of air outlet holes is different, and a crushing impeller for crushing bubbles formed by the plasma flowing out of the large-diameter air outlet is provided at a position of the stirring shaft corresponding to the large-diameter air outlet, and the stirring shaft is provided with a plurality of spaced-apart spoilers along its axial direction.

[0007] Furthermore, the blade cross-section of the crushing impeller is an arc-shaped structure.

[0008] Furthermore, the axial extension length of the blades of the crushing impeller is equal to the axial distribution length of the corresponding air outlet holes.

[0009] Furthermore, the spoiler is an annular sheet.

[0010] Furthermore, the stirring impeller includes at least two impeller bodies.

[0011] Furthermore, the blade thickness of the impeller body located below is greater than the blade thickness of the impeller body located above, and the blade height of the impeller body located above is greater than the blade height of the impeller body located below.

[0012] Furthermore, the above-mentioned spoiler is provided between two adjacent impeller bodies.

[0013] Furthermore, the stirring device also includes a plasma generating unit and a gas distribution unit;

[0014] The plasma generating unit includes a DBD generator, the gas distribution unit includes an air compressor, a mass flow controller and an air pump connected in sequence, and the DBD generator is located between the mass flow controller and the air pump.

[0015] The beneficial effects of the present invention are as follows: the present invention introduces a low-temperature plasma external field, which can treat drilling wastewater through various methods such as high-energy electron radiation, oxidation of active particles such as free radicals, and ultraviolet decomposition, thereby improving treatment efficiency while reducing the generation of by-products. At the same time, the introduction of low-temperature plasma can reduce the demand for chemical catalysts, which not only reduces capital costs but also reduces pollution to the environment. In addition, the use of a stirring impeller and a spoiler significantly improves the liquid-solid mixing in the stirring tank, improves reaction efficiency, and makes wastewater treatment more thorough. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described below with reference to the accompanying drawings and examples.

[0017] Figure 1 3D schematic diagram of the stirring shaft in the present invention;

[0018] Figure 2 This is a front view of the stirring shaft of the present invention;

[0019] Figure 3 It is a schematic diagram of the overall structure of the present invention;

[0020] In the picture:

[0021] 1. Stirring shaft; 101. Air inlet; 102. Air outlet; 102a. Small-diameter air outlet; 102b. Large-diameter air outlet;

[0022] 2. Mixing impeller; 201. First impeller body; 202. Second impeller body;

[0023] 3. Crushing impeller;

[0024] 4. Spoiler; 401. Upper spoiler ring; 402. Middle spoiler ring; 403. Lower spoiler ring;

[0025] 5. Wastewater treatment tank;

[0026] 6. Air compressor;

[0027] 7. Mass flow controller;

[0028] 8. Positive plate;

[0029] 9. Negative plate;

[0030] 10. DBD generator;

[0031] 11. Oscilloscope;

[0032] 12. Ground terminal;

[0033] 13. Air pump. DETAILED DESCRIPTION

[0034] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating the basic structure of the present invention only in a schematic manner. Therefore, they only show components relevant to the present invention, and directions and references such as up, down, left, right, etc., are merely used to facilitate the description of features in the drawings. The following detailed description is therefore not to be taken in a limiting sense, and the scope of the claimed subject matter is defined solely by the appended claims and their equivalents.

[0035] Example 1:

[0036] like Figure 1 and Figure 2 As shown, the present invention is a low-temperature plasma stirring device for treating oilfield drilling wastewater, which is used to stir wastewater in a wastewater treatment tank 5. The stirring device includes a stirring shaft 1 with an inner cavity and a stirring impeller 2 fixed to the bottom of the stirring shaft 1;

[0037] The stirring shaft 1 is sealed at one end along its axial direction, and the other end is connected to the inner cavity to form an air inlet 101 for the plasma to enter, and the stirring shaft 1 is provided with a plurality of groups of air outlet holes 102 along its axial direction that are connected to the inner cavity to allow the plasma in the inner cavity to flow out;

[0038] Each group of air outlet holes 102 includes a plurality of air outlet holes 102 distributed axially and circumferentially along the stirring shaft 1. The apertures of each group of air outlet holes 102 are different, and the portion of the stirring shaft 1 corresponding to the large-diameter air outlet holes 102b is provided with a crushing impeller 3 for crushing bubbles formed by the plasma flowing out of the large-diameter air outlet holes 102b, thereby accelerating the plasma treatment process of the wastewater. In this embodiment, two groups of air outlet holes 102 are provided, namely small-diameter air outlet holes 102a and large-diameter air outlet holes 102b, and the large-diameter air outlet holes 102b are located below the small-diameter air outlet holes 102a. The arrangement of the small-diameter air outlet holes 102a and the large-diameter air outlet holes 102b can guide the flow of fluid and evenly mix the fluids in different areas. If the apertures are the same, insufficient flow uniformity may result, and the purpose of effective mixing cannot be achieved. The large-diameter air outlet holes 102b allow more fluid to flow, increasing the overall flow rate, while the small-diameter air outlet holes 102a can generate stronger local shear force, which helps to refine particles or promote the mixing of liquids and solids. The small bubbles formed by the plasma flowing out from the small-diameter outlet 102a are easy to break, and they can fully contact with the wastewater to react. The large bubbles formed by the plasma flowing out from the large-diameter outlet 102b are not easy to break. When the stirring shaft 1 rotates, it drives the breaking impeller 3 to rotate synchronously to break up the large bubbles so that they can fully contact with the wastewater.

[0039] Described agitator shaft 1 is axially equipped with some spaced spoilers 4, in the present embodiment, spoiler 4 quantity is three, three are followed successively by upper spoiler ring 401, middle spoiler ring 402 and lower spoiler ring 403 from top to bottom, lower spoiler ring 403 is mainly used in the strong flow that produces bottom area, avoids particle precipitation, helps the solid materials deposited to be resuspended, can help fluid to rise from bottom area simultaneously, guarantees even mixing.Middle spoiler ring 402 is generally used in the central area of ​​wastewater treatment tank 5 and produces strong circulating flow, guarantees that fluid flows to the edge from the central authorities of tank, further improves the uniformity of mixing, and it is usually responsible for most fluid exchange and circulation.Upper spoiler ring 401 is mainly used in the flow of control upper area, prevents liquid surface from forming eddy current or dead zone, it can reduce the involvement (preventing foam generation) of surface gas, guarantees the even mixing of whole liquid height.

[0040] First, the driving mechanism drives the stirring shaft 1 to rotate, and then the plasma enters the inner cavity of the stirring shaft 1 from the air inlet 101 and flows out from each group of air outlets 102. After the small-diameter air outlet 102a enters the wastewater, it is quickly broken under the action of water pressure to contact the wastewater. After the large-diameter air outlet 102b enters the wastewater, it is broken under the action of the crushing impeller 3 to contact the wastewater. In this embodiment, the introduction of low-temperature plasma technology into drilling wastewater treatment can significantly reduce the use of chemical agents, greatly reduce the generation of by-products, and facilitate the subsequent treatment of wastewater. For high-viscosity drilling wastewater, plasma can react and degrade viscous substances in the wastewater to achieve the effect of reducing the viscosity of the wastewater. In addition, the stirring process in the wastewater treatment tank 5 is smoother. At the same time, the stirring impeller 2 and the spoiler 4 rotate to stir the wastewater. The stirring action can help the plasma be evenly distributed in the wastewater, allowing the plasma to fully react with the wastewater. In addition, the plasma can also remove various harmful heavy metal ions, organic matter, etc. generated by wastewater treatment, making the wastewater treatment more thorough and significant.

[0041] In some examples, the blade cross-section of the crushing impeller 3 is an arc-shaped structure, roughly a quarter of a circle. The stirring impeller 2 is located below the crushing impeller 3. The arc-shaped blades can guide the fluid to flow through the blade surface more smoothly, reducing the generation of turbulence and eddy currents near the arc-shaped blades, and reducing the direct impact force on the front of the blades. Therefore, the reaction force of the fluid on the blades can be reduced, thereby reducing the resistance of the stirring impeller 2.

[0042] In some examples, the axial extension length of the blades of the crushing impeller 3 is equal to the axial distribution length of the corresponding large-diameter air outlet holes 102b, and each blade is located between two adjacent rows of air outlet holes 102 to ensure that each bubble formed by flowing out of the large-diameter air outlet holes 102b can be crushed by the crushing impeller 3.

[0043] In some examples, the spoiler 4 is an annular thin sheet, and the crushing impeller 3 is located between the upper spoiler ring 401 and the middle spoiler ring 402 .

[0044] In some examples, the stirring impeller 2 includes a nut threadedly connected to the stirring shaft 1 and at least two impeller bodies located on the nut. This embodiment uses a double-layer impeller, which can effectively improve the flow conditions in the stirring tank. The impeller body located at the bottom (i.e., the first impeller body 201) can suspend the particulate matter in the wastewater to prevent particle deposition; the impeller body located at the top (i.e., the second impeller body 202) can ensure the flow of the upper wastewater, so that the treatment and reaction of the wastewater can be carried out more thoroughly, further improving the performance of the reactor.

[0045] In some examples, the lower first impeller body 201 typically needs to operate in a relatively high-resistance environment. Therefore, the blades in the first impeller body 201 are thicker than those in the upper second impeller body 202 to withstand the higher flow resistance. Furthermore, the central area of ​​the wastewater treatment tank 5 requires a larger stirring coverage area to promote circulation throughout the entire height of the liquid. Therefore, the height of the upper second impeller body 202 is greater than that of the lower first impeller body 201, thereby creating a larger stirring range in the upper layer and enhancing overall circulation. The blades of the first impeller body 201 are tilted at an angle of 20°-35°.

[0046] In some examples, the above-mentioned spoiler ring is provided between two adjacent impeller bodies, that is, the lower spoiler ring 403 is provided between two adjacent impeller bodies. On the one hand, it is used to generate strong disturbance at the bottom of the wastewater treatment tank 5 to avoid particle sedimentation and ensure uniform mixing. On the other hand, it can be used to install the lower impeller body. The blades of the lower impeller body are evenly distributed in a vertical state at the bottom of the lower spoiler ring 403, which can make the stirring of the bottom area inside the wastewater treatment tank 5 more sufficient.

[0047] In some examples, such as Figure 3 As shown, the stirring device also includes a plasma generating unit and a gas distribution unit;

[0048] The plasma generating unit includes a DBD generator 10, an oscilloscope 11, and electrode plates. The plasma generator provides electrical energy to ionize the gas between the electrode plates to form a low-temperature plasma. The positive plate 8 is connected to the DBD generator 10 via a wire, and the negative plate 9 is connected to the ground terminal 12 via a wire. The high-voltage power supply in the plasma generator has an adjustable discharge voltage range of 0-30 kV and a frequency of 50 kHz. In this embodiment, the DBD generator 10 is adjusted based on the displayed data of the oscilloscope 11 to break down the air between the positive plate 8 and the negative plate 9, thereby generating a large number of high-energy electrons and active particles. The positive plate 8 and the negative plate are made of copper with a thickness of 10 mm. The dielectric barrier layer is made of quartz glass with a dielectric thickness of 5 mm. The electrode spacing is 40 mm, and the electrode plate length depends on the specific situation.

[0049] The gas distribution unit includes an air compressor 6, a mass flow controller 7 and an air pump 13 connected in sequence. The DBD generator 10 is located between the mass flow controller and the air pump 13. The air compressor 6 compresses the air to a high-pressure state, stores it, and delivers it to the mass flow controller 7. The mass flow controller 7 controls the flow of gas entering between the electrode plates to prevent problems with the entire system caused by excessive or insufficient air input. Finally, the air pump 13 delivers the generated low-temperature plasma into the inner cavity of the stirring shaft 1, and enters the wastewater to be treated from the air outlet 102 for reaction, thereby achieving the purpose of wastewater treatment.

[0050] Working principle:

[0051] First, the driving mechanism drives the stirring shaft 1 to rotate, and then the plasma enters the inner cavity of the stirring shaft 1 from the air inlet 101 and flows out from each group of air outlets 102. After the small-diameter air outlet 102a enters the wastewater, it is quickly broken under the action of water pressure to come into contact with the wastewater. After the large-diameter air outlet 102b enters the wastewater, it is broken under the action of the crushing impeller 3 to come into contact with the wastewater. At the same time, the stirring impeller 2 and the spoiler 4 rotate to stir the wastewater. The stirring action can help the plasma be evenly distributed in the wastewater, allowing the plasma to fully react with the wastewater. In addition, the plasma can also remove various harmful heavy metal ions, organic matter, etc. generated by wastewater treatment, making the wastewater treatment more thorough and significant.

[0052] The above description of the preferred embodiments of the present invention is intended to serve as a guide. Based on the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A low-temperature plasma stirring device for treating oilfield drilling wastewater, characterized in that: It comprises a stirring shaft (1) having an inner cavity and a stirring impeller (2) fixed at the bottom of the stirring shaft (1); One end of the stirring shaft (1) is blocked along its axial direction, and the other end is connected to the inner cavity to form an air inlet (101) for plasma to enter, and the stirring shaft (1) is provided with a plurality of groups of air outlet holes (102) along its axial direction that are connected to the inner cavity for plasma in the inner cavity to flow out, the aperture of each group of air outlet holes (102) is different, and a crushing impeller (3) for crushing bubbles formed by the plasma flowing out of the large-diameter air outlet holes (102b) is provided at a portion of the stirring shaft (1) corresponding to the large-diameter air outlet holes (102b), and the stirring shaft (1) is provided with a plurality of spaced-apart spoilers (4) along its axial direction.

2. The low-temperature plasma stirring device for treating oilfield drilling wastewater according to claim 1, characterized in that: The blade cross section of the crushing impeller (3) is an arc-shaped structure.

3. The low-temperature plasma stirring device for treating oilfield drilling wastewater according to claim 1, characterized in that: The axial extension length of the blades of the crushing impeller (3) is equal to the axial distribution length of the corresponding air outlet holes (102).

4. The low-temperature plasma stirring device for treating oilfield drilling wastewater according to claim 1, characterized in that: The spoiler (4) is an annular thin sheet.

5. The low-temperature plasma stirring device for treating oilfield drilling wastewater according to claim 1, characterized in that: The stirring impeller (2) comprises at least two impeller bodies.

6. The low-temperature plasma stirring device for treating oilfield drilling wastewater according to claim 5, characterized in that: The blade thickness of the impeller body located at the bottom is greater than the blade thickness of the impeller body located at the top, and the blade height of the impeller body located at the top is greater than the blade height of the impeller body located at the bottom.

7. The low-temperature plasma stirring device for treating oilfield drilling wastewater according to claim 5, characterized in that: The spoiler (4) is provided between two adjacent impeller bodies.

8. The low-temperature plasma stirring device for treating oilfield drilling wastewater according to claim 1, characterized in that: The stirring device also includes a plasma generating unit and a gas distribution unit; The plasma generating unit comprises a DBD generator (10), the gas distribution unit comprises an air compressor (6), a mass flow controller (7) and an air pump (13) connected in sequence, and the DBD generator (10) is located between the mass flow controller (7) and the air pump (13).

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