Low-temperature plasma stirring device for oil field drilling wastewater treatment

Abstract

The invention relates to the technical field of wastewater treatment, in particular to a low-temperature plasma stirring device for oilfield drilling wastewater treatment, which comprises a stirring shaft and a stirring impeller, one end of the stirring shaft is blocked, the other end of the stirring shaft is communicated with an inner cavity to form an air inlet, and a plurality of groups of air outlets are axially formed in the stirring shaft; the pore diameters of the groups of air outlet holes are different, crushing impellers are arranged at the parts, corresponding to the large-diameter air outlet holes, of the stirring shaft, and a turbulent flow piece is mounted on the stirring shaft in the axial direction of the stirring shaft; the low-temperature plasma external field is introduced, the drilling wastewater can be treated through various methods such as high-energy electron radiation, oxidation of active particles such as free radicals, ultraviolet decomposition and the like, the treatment efficiency is improved, meanwhile, the requirement for a chemical catalyst is reduced, the capital cost is reduced, and pollution to the environment is reduced; in addition, the liquid-solid mixing condition in the stirring tank is obviously improved by utilizing the stirring impeller and the spoiler, the reaction efficiency is improved, and the wastewater treatment is 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] In the process of oil and gas field mining and drilling, drilling wastewater containing a large amount of oil, solid particles, heavy metal ions and various additives will be produced. Because drilling wastewater is not only complex in composition, but also highly polluting and difficult to treat, it is easy to cause very serious environmental pollution. The use of mixing tanks plays an important role in the current drilling wastewater treatment technology, which can make wastewater mixing and chemical treatment more thorough, improve the efficiency of drilling wastewater treatment, and enhance the treatment effect. In traditional wastewater treatment, catalysts are usually added to the mixing tank. However, when this method is used, a large amount of chemical agents are used, which increases the production of by-products, and it is easy to cause uneven mixing of catalyst particles and particle deposition, resulting in uneven concentration of reactants and reduced reaction efficiency. In addition, there are problems such as too long reaction time and the inability of substances in some areas to react. At the same time, traditional mixing tanks need to provide stronger power when treating wastewater with high concentration or relatively viscous, and the treatment cost consumption will increase significantly.

[0003] Low-temperature plasma technology treats drilling wastewater by utilizing the synergistic effects of multiple methods such as high-energy electrons, ions, atoms, and free radicals in 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 wastewater; secondly, a large amount of strong oxidants such as ozone and hydrogen peroxide will be generated during the ionization process of low-temperature plasma, which will 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 will also generate 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 low-temperature plasma discharge fully treat 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 designs 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 problem that in traditional wastewater treatment, a catalyst is usually placed in a stirring tank, a large amount of chemical agents are used, the generation of by-products is increased, and phenomena such as uneven mixing of catalyst particles and particle deposition are prone to occur, resulting in uneven concentration of reactants 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 with the inner cavity to form an air inlet for plasma to enter, and a plurality of groups of air outlet holes connected with the inner cavity are opened along its axial direction for plasma in the inner cavity to flow out, each group of air outlet holes has a different aperture, 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 a plurality of spoilers arranged at intervals are installed on the stirring shaft 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 comprises a DBD generator, the gas distribution unit comprises an air compressor, a mass flow controller and an air pump which are 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, and can treat drilling wastewater through various methods such as high-energy electron radiation, oxidation of active particles such as free radicals, ultraviolet decomposition, etc., which improves the treatment efficiency while also 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 to stir significantly improves the liquid-solid mixing in the stirring tank, improves the reaction efficiency, and makes the wastewater treatment more thorough. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0017] Figure 1 It is a three-dimensional schematic diagram of the stirring shaft in the present invention;

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

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

[0020] In the figure:

[0021] 1. stirring shaft; 101. air inlet; 102. air outlet; 102a. small-diameter air outlet; 102b. large-diameter air outlet;

[0022] 2. stirring 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 that illustrate the basic structure of the present invention in a schematic manner only, and therefore only show the components related to the present invention, and directions and references such as up, down, left, right, etc. may only be used to help describe the features in the drawings. Therefore, the following specific embodiments are not to be taken in a limiting sense, and the scope of the subject matter claimed is limited only by the attached claims and their equivalents.

[0035] Embodiment 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 the wastewater in the wastewater treatment tank 5. The stirring device includes a stirring shaft 1 with an inner cavity and a stirring impeller 2 fixed at the bottom of the stirring shaft 1;

[0037] The stirring shaft 1 is blocked at one end 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;

[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, and 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 hole 102b is provided with a crushing impeller 3 for crushing bubbles formed by the plasma flowing out of the large-diameter air outlet hole 102b, so as to accelerate the process of plasma treatment of wastewater. In this embodiment, two groups of air outlet holes 102 are provided, namely, the small-diameter air outlet hole 102a and the large-diameter air outlet hole 102b, and the large-diameter air outlet hole 102b is located below the small-diameter air outlet hole 102a. The setting of the small-diameter air outlet hole 102a and the large-diameter air outlet hole 102b can guide the flow of fluid and make the fluids in different regions evenly mixed. 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 hole 102b allows more fluid to flow and enhances the overall flow rate, and the small-diameter air outlet hole 102a can generate stronger local shear force, which helps to refine particles or promote the mixing of liquid and solid. The small bubbles formed by the plasma flowing out from the small-diameter outlet 102a are easy to break, and 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] The stirring shaft 1 is provided with several spaced spoilers 4 along its axial direction, and the spoilers 4 quantity is three in the present embodiment, and the three are upper spoiler ring 401, middle spoiler ring 402 and lower spoiler ring 403 from top to bottom, and the lower spoiler ring 403 is mainly used for generating the strong flow in the bottom area, avoiding the precipitation of particles, helping to resuspend the deposited solid materials, and can help the fluid to rise from the bottom area at the same time, ensuring uniform mixing. The middle spoiler ring 402 is usually used for generating strong circulation flow in the central area of ​​the wastewater treatment tank 5, ensuring that the fluid flows from the center of the tank to the edge, further improving the uniformity of mixing, and it is usually responsible for most of the fluid exchange and circulation. The upper spoiler ring 401 is mainly used for controlling the flow in the upper area, preventing the liquid surface from forming eddy current or dead zone, and it can reduce the involvement of surface gas (preventing foam generation), ensuring the uniform mixing of the 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 low-temperature plasma technology is introduced into the drilling wastewater treatment, which 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 with 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 to be evenly distributed in the wastewater, so that the plasma fully reacts with the wastewater. In addition, the plasma can also remove various harmful heavy metal ions, organic matter, etc. generated by the wastewater treatment, so that the wastewater treatment is 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, reduce the generation of turbulence and eddies near the arc-shaped blades, and reduce 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. The present embodiment adopts a double-layer impeller, which can effectively improve the flow condition in the stirring tank. The impeller body located at the bottom (i.e., the first impeller body 201) can suspend the particles 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 first impeller body 201 located at the bottom usually needs to work in a relatively high resistance environment, so the thickness of the blades located at the first impeller body 201 is greater than the thickness of the second impeller body 202 located at the top to withstand the higher flow resistance; and the central area of ​​the wastewater treatment tank 5 needs to have a larger stirring coverage to promote the circulation flow of the entire liquid height. Therefore, the height of the second impeller body 202 located at the top is greater than the height of the first impeller body 201 located at the bottom, thereby generating a larger stirring range at the upper layer to enhance the overall circulation, and the blades of the first impeller body 201 are tilted, with an inclination 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 precipitation 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 comprises a DBD generator 10, an oscilloscope 11 and an electrode plate. The plasma generator provides electric 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 through a wire, and the negative plate 9 is connected to the ground terminal 12 through a wire. The adjustment range of the discharge voltage of the high-voltage power supply in the plasma generator is 0-30KV, and the frequency is 50KHz. In this embodiment, the DBD generator 10 is adjusted to break down the air between the positive plate 8 and the negative plate 9 through the display data of the oscilloscope 11 to generate 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 10mm, the dielectric barrier layer material is quartz glass with a dielectric thickness of 5mm, the electrode spacing is 40mm, and the length of the electrode plate 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 in 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 contact the wastewater. After the large-diameter air outlet 102b enters the wastewater, it is broken under the action of the breaking impeller 3 to contact 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 to be evenly distributed in the wastewater, so that the plasma can fully react with the wastewater. In addition, the plasma can also remove various harmful heavy metal ions, organic matter, etc. generated by the wastewater treatment, so that the wastewater treatment is more thorough and significant.

[0052] The above-mentioned ideal embodiments of the present invention are for inspiration. Through the above-mentioned description, relevant staff can make various changes and modifications without departing from the technical idea of ​​the present invention. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope 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) along its axial direction is blocked, 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 to allow plasma in the inner cavity to flow out, each group of air outlet holes (102) has a different aperture, and a crushing impeller (3) for crushing bubbles formed by plasma flowing out of the large-diameter air outlet holes (102b) is provided at a position 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 spoilers (4) distributed at intervals along its axial direction.

2. A 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. A 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) which are 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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