An oil-containing sewage treatment device and a regulation and control method for vertical shallow purification equipment in series combination operation

Abstract

The application provides an oil-containing sewage treatment device and a regulation and control method for series combination operation of vertical shallow purification equipment, wherein, along the sewage flow direction, a first tubular micro-bubble generator, a first vertical shallow purification equipment, a second tubular micro-bubble generator and a second vertical shallow purification equipment are sequentially communicated; the first tubular micro-bubble generator and the second tubular micro-bubble generator are both provided with a medicine injection port communicated with an external medicine injection pipeline; the top oil outlet of the first vertical shallow purification equipment and the second vertical shallow purification equipment is communicated with an external oil outlet pipeline; the gas phase inlet of the first tubular micro-bubble generator and the gas phase inlet of the second tubular micro-bubble generator are both provided with a conducting state and a blocking state between the gas phase inlet and an external gas injection pipeline. According to the oil content in the sewage, the oil removal efficiency can be improved under the premise of saving energy consumption, so as to efficiently adapt to different oil content and emulsification degree of incoming liquid working conditions.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to an oily wastewater treatment device and control method that combines vertical shallow purification equipment in series. Background Technology

[0002] Currently, most major oilfields have entered the high water-cut or ultra-high water-cut development stage, leading to a year-on-year increase in produced fluid, i.e., produced water volume. Removing oil phase and suspended solids (SS) from produced water is the primary challenge in produced water treatment. Especially for offshore oil and gas field produced water treatment, limited by platform space and load-bearing capacity, the treatment process typically employs a reinjection purification process of "conventional horizontal oil separator or hydrocyclone - air flotation - filtration," facing severe challenges such as high hydraulic load and short hydraulic retention time for individual equipment. Conventional inclined plate oil separators, static hydrocyclones, and air flotation devices for oily wastewater treatment generally suffer from drawbacks such as large equipment footprint, poor adaptability to operating conditions, and high chemical reagent consumption, gradually failing to meet the actual needs of oily wastewater treatment. Therefore, there is an urgent need for new, efficient, integrated oil-water separation equipment.

[0003] In existing technologies, inclined plate oil separators, as a common oil-water separation device, are based on gravity separation and shallow pool theory. They increase the contact area of ​​the separation zone by using inclined plate groups to improve oil-water separation efficiency. Chinese patent ZL201911168972.0 discloses an inclined plate oil separator for oily wastewater, the main body of which consists of a box and inclined plate components arranged along the width direction inside the box, and a vertical oil weir plate. The inclined plate group is composed of multiple inclined plate units stacked parallel to each other, and the overall structure adopts a horizontal placement. Although this solves the problem of unreasonable internal arrangement of current conventional horizontal inclined plate oil separators and improves the ability to treat oily wastewater, the horizontal placement also has disadvantages such as a non-compact structure and a long hydraulic retention time. Air flotation devices, on the other hand, are based on the principle of air flotation separation. By injecting microbubbles into the water, the bubbles adhere to the surface of oil droplets, and buoyancy carries them to the water surface for separation. Based on the flow state of the air flotation separation zone, they can be divided into horizontal horizontal flow type and vertical vertical flow type.

[0004] In the prior art, Chinese patent ZL202411711305.3 discloses an air flotation unit for oily wastewater treatment, whose internal chamber is divided into a mixing tank, an air flotation tank, an oil collection tank, and a slag collection tank by partitions. This solves the shortcomings of existing air flotation devices, which, due to the fixed size of the scraper plates, cannot efficiently handle small volumes of wastewater or small amounts of impurities, thus saving wastewater treatment costs and time. However, this air flotation device also uses a horizontal placement, and although its separation efficiency is high, its structure is not compact, it occupies a large area, and has a long hydraulic retention time, making it unsuitable for the space-constrained conditions of offshore platforms. To address this issue, some offshore oilfields use vertical air flotation, which significantly reduces the equipment footprint compared to horizontal air flotation, but suffers from disadvantages such as low separation efficiency and high hydraulic load per unit.

[0005] Furthermore, driven by the urgent need for "compliant discharge" or "compliant reinjection" of oily wastewater from offshore platforms, several new process combinations have emerged in recent years. For example, Chinese patent ZL201810022386.4 discloses an oily wastewater treatment system and process, whose main equipment includes an oil separator, a flocculation tank, and a sedimentation tank. This process obtains primary oily wastewater through the oil separator, then demulsifies it and performs flocculation in the flocculation tank, followed by primary filtration in the sedimentation tank, and finally achieves compliant treatment of the oily wastewater through microporous filtration in a vacuum tank. This process effectively removes light oil, heavy suspended oil, emulsified oil, dispersed oil, and dissolved oil from oily wastewater, but it suffers from drawbacks such as long processing time and large reagent dosage. Chinese patent ZL202010038473.6 discloses a "filtration-cyclone separation-photocatalytic degradation" treatment process, whose main equipment includes a sedimentation tank, a cyclone separator, a cyclone flotation device, and a photocatalytic degradation device. This process has high processing efficiency, but the equipment is sensitive to the conditions of the incoming liquid, and the catalyst is expensive, making scale-up difficult. Chinese patent ZL202211574858.X discloses a standardized treatment process for an oily wastewater treatment unit in an offshore oilfield. The main equipment includes an inclined plate oil separator, an air flotation separator, a production water buffer tank, a walnut shell feed pump, a walnut shell filter, a sludge tank, and a sludge pump. This process uses an inclined plate oil separator for initial separation, followed by further purification via air flotation, and finally filtration through a walnut shell filter to ensure the oily wastewater meets standards for reinjection. The process is relatively simple, but it suffers from the drawback of being unable to control the air flotation and inclined plate oil separator, resulting in poor adaptability and an inability to efficiently remove oil according to different incoming liquid conditions.

[0006] In summary, existing oily wastewater treatment equipment occupies a large area and cannot select a suitable oil removal device or method based on the oil content in the wastewater, resulting in low oil removal efficiency and high energy consumption. Summary of the Invention

[0007] The purpose of this invention is to provide an oily wastewater treatment device and control method for vertical shallow purification equipment operating in series, to solve the technical problem that existing oily wastewater treatment equipment cannot select a suitable oil removal method based on the oil content of the wastewater, resulting in low oil removal efficiency. The various technical effects of the preferred solutions among the many technical solutions provided by this invention are detailed below.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] The oily wastewater treatment device provided by this invention, consisting of a series combination of vertical shallow purification equipment, is characterized by comprising a primary tubular microbubble generator, a primary vertical shallow purification device, a secondary tubular microbubble generator, and a secondary vertical shallow purification device, wherein:

[0010] The inlet of the first-stage tubular microbubble generator is connected to the external oily wastewater pipeline; the inlet of the first-stage vertical shallow purification equipment is connected to the bottom outlet of the first-stage tubular microbubble generator; the inlet of the second-stage tubular microbubble generator is connected to the bottom outlet of the first-stage vertical shallow purification equipment; and the inlet of the second-stage vertical wastewater purification equipment is connected to the bottom outlet of the second-stage tubular microbubble generator.

[0011] Both the primary tubular microbubble generator and the secondary tubular microbubble generator have injection ports that are connected to the external drug delivery pipeline, and the top oil outlets of both the primary vertical shallow purification equipment and the secondary vertical shallow purification equipment are connected to the external oil delivery pipeline.

[0012] The gas phase inlet of the first-stage tubular microbubble generator and the external gas injection pipeline, as well as the gas phase inlet of the second-stage tubular microbubble generator and the external gas injection pipeline, are both in a conductive state and a blocked state.

[0013] Preferably, a first gas injection line valve is provided between the gas phase inlet of the first-stage tubular microbubble generator and the external gas injection pipeline. The first gas injection line valve is used to control whether the gas phase inlet of the first-stage tubular microbubble generator and the external gas injection pipeline are in a conducting state or a blocking state.

[0014] A second gas injection line valve is provided between the gas phase inlet of the two-stage tubular microbubble generator and the external gas injection pipeline. The second gas injection line valve is used to control whether the gas phase inlet of the two-stage tubular microbubble generator and the external gas injection pipeline are in a conducting or blocking state.

[0015] Preferably, the primary tubular microbubble generator and the secondary tubular microbubble generator have the same structure, both including a dissolved gas tube and a dissolved gas releaser. The bottom of the dissolved gas tube is provided with a dissolved gas water outlet pipe, which has a dissolved gas water outlet. The dissolved gas water outlet is connected to the primary vertical shallow purification device or the secondary vertical shallow purification device through the dissolved gas releaser.

[0016] Preferably, the dissolved air pipe includes a straight pipe section and an inner cylinder fixed inside the straight pipe section. An outer annular cavity is provided between the inner cylinder and the inner wall of the straight pipe section, and some of the fluid injected into the dissolved air pipe can circulate between the inner cylinder and the outer annular cavity.

[0017] Preferably, the primary tubular microbubble generator and the secondary tubular microbubble generator further include an arc-shaped baffle, which is located below the inner cylinder, with the concave side of the arc-shaped baffle facing the inner cylinder, and a flow port is formed between the inner cylinder and the arc-shaped baffle.

[0018] Preferably, the primary tubular microbubble generator and the secondary tubular microbubble generator further include a water inlet section with a water inlet, a throat formed in the middle of the water inlet section, the inner diameter of the throat being smaller than the inner diameter of the rest of the water inlet section, and a swirl vane provided in the water inlet section, the swirl vane being located on the upstream side of the throat.

[0019] The throat tube is also connected to a drug injection tube and a gas injection tube, with the drug injection port located on the drug injection tube and the gas phase inlet located on the gas injection tube.

[0020] Preferably, the primary vertical shallow purification device and the secondary vertical shallow purification device have the same structure, both including an inlet pipe, a tank, and an inclined plate assembly, wherein:

[0021] The inlet end of the water inlet pipe can be connected to the bottom outlet of the first-stage tubular microbubble generator or the second-stage tubular microbubble generator, and the outlet end of the water inlet pipe is connected to the tank body. The inclined plate assembly is located above the outlet of the water inlet pipe and is used to coalesce tiny oil droplets and suspended impurities.

[0022] Preferably, the inclined plate assembly includes concentric frustum inclined plates. In each group of concentric frustum inclined plates, the concentric frustum inclined plates are arranged at intervals along the vertical direction. The spacing between adjacent concentric frustum inclined plates is equal or unequal, and there is a channel for fluid flow between adjacent concentric frustum inclined plates.

[0023] Preferably, the water inlet pipe includes a connected horizontal section and a vertical section, wherein:

[0024] The horizontal section is sealed and passes through the tank wall of the tank body, and can be connected to the bottom outlet of the primary tubular microbubble generator or the secondary tubular microbubble generator;

[0025] The vertical section is arranged along the axis of the tank body, the outlet of the vertical section is arranged towards the inclined plate assembly, and a flow equalization grid is provided at the outlet of the vertical section.

[0026] This invention provides a method for controlling the treatment of oily wastewater using a series combination of vertical shallow purification devices. The method, employing the aforementioned series combination of vertical shallow purification devices for oily wastewater treatment, includes:

[0027] When the oil content in the wastewater is less than a first set value, the gas phase inlet of the primary tubular microbubble generator and the external gas injection pipeline, as well as the gas phase inlet of the secondary tubular microbubble generator and the external gas injection pipeline, are both blocked. Flocculant is added to the primary and secondary tubular microbubble generators only through the injection port. At this time, both the primary vertical shallow purification device and the secondary vertical shallow purification device are used as vertical inclined plate oil separators.

[0028] When the oil content in the wastewater is greater than or equal to the first set value and less than or equal to the second set value, the gas phase inlet of the primary tubular microbubble generator is controlled to be in a blocked state with the external gas injection pipeline, and the gas phase inlet of the secondary tubular microbubble generator is controlled to be in a conductive state with the external gas injection pipeline. Flocculant is added to the primary tubular microbubble generator and the secondary tubular microbubble generator through the injection port, and gas is introduced into the secondary tubular microbubble generator through the gas phase inlet. At this time, the primary vertical shallow purification equipment is used as a vertical inclined plate oil separator, and the secondary vertical shallow purification equipment is used as a vertical shallow air flotation tank.

[0029] When the oil content in the wastewater exceeds the second set value, the gas phase inlet of the primary tubular microbubble generator and the external gas injection pipeline, as well as the gas phase inlet of the secondary tubular microbubble generator and the external gas injection pipeline, are both kept in a conductive state. Flocculant is added to both the primary and secondary tubular microbubble generators through the injection port, and gas is introduced into both the primary and secondary tubular microbubble generators through the gas phase inlet. At this time, both the primary and secondary vertical shallow purification devices are used as vertical shallow flotation tanks.

[0030] The oily wastewater is passed sequentially through a primary tubular microbubble generator, a primary vertical shallow purification device, a secondary tubular microbubble generator, and a secondary vertical shallow purification device.

[0031] The oily wastewater treatment device and control method for vertical shallow purification equipment in series operation provided by this invention have the following advantages compared with the prior art: The device includes two-stage tubular microbubble generators and two-stage vertical shallow purification equipment. By controlling the connection and disconnection between the gas phase inlet of the first-stage tubular microbubble generator and the external gas injection pipeline, and between the gas phase inlet of the second-stage tubular microbubble generator and the external gas injection pipeline, both the first-stage and second-stage vertical shallow purification equipment can achieve the conversion between a vertical shallow flotation tank and a vertical inclined plate oil separator. This allows for improved oil removal efficiency while saving energy, based on the oil content of the wastewater, thus efficiently adapting to different oil contents and emulsification levels of the incoming liquid, achieving flexible control through "homogeneous design and differentiated operation." The process flow is simple and reliable, with a compact structure and high integration. The overall vertical series structure significantly reduces the floor space compared to traditional horizontal equipment, making it particularly suitable for space-constrained environments such as offshore platforms. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 A schematic diagram of the structure of an oily wastewater treatment device that operates in series with vertical shallow purification equipment, as provided in an embodiment of the present invention;

[0034] Figure 2 A schematic diagram of the structure of a single-stage tubular microbubble generator provided in an embodiment of the present invention;

[0035] Figure 3 A schematic diagram of the structure of a primary vertical shallow purification device provided in an embodiment of the present invention.

[0036] In the diagram, 1. First gas injection line valve; 2. Second gas injection line valve; 3. External gas injection pipeline; 4. External drug injection pipeline; 5. External oily wastewater pipeline; 6. First-stage tubular microbubble generator; 61. Dissolved gas pipe; 62. Dissolved gas release device; 611. Water inlet; 612. Swirl vane; 613. Throat; 614. Drug injection pipe; 615. Gas injection pipe; 616. Straight pipe section; 617. Inner cylinder; 618. Dissolved gas outlet pipe; 619. Arc-shaped baffle; 620. Outer annular cavity; 7. First-stage vertical shallow purification equipment; 71. Water inlet pipe; 72. Bottom flow port; 73. Top oil outlet; 74. Concentric cone inclined plate; 75. Flow equalization grid; 8. Second-stage tubular microbubble generator; 9. Second-stage vertical shallow purification equipment; 10. External oil phase pipeline; 11. Wastewater outlet. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0038] In the description of this invention, it should be understood that the terms "center," "length," "width," "height," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and "side," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0039] This invention provides an oily wastewater treatment device that combines vertical shallow purification equipment in series. While saving energy, it improves oil removal efficiency, thereby efficiently adapting to different oil content and emulsification levels of incoming liquids and achieving flexible control through "homogeneous design and differentiated operation".

[0040] The following is combined Figures 1-3 The technical solution provided by this invention will be described in more detail below.

[0041] Example 1:

[0042] See Figures 1-3As shown, the oily wastewater treatment device for series operation of vertical shallow purification equipment provided by the present invention includes a primary tubular microbubble generator 6, a primary vertical shallow purification device 7, a secondary tubular microbubble generator 8, and a secondary vertical shallow purification device 9. Specifically: the inlet 611 of the primary tubular microbubble generator 6 is connected to the external oily wastewater pipeline 5; the inlet of the primary vertical shallow purification device 7 is connected to the bottom outlet of the primary tubular microbubble generator 6; and the inlet 611 of the secondary tubular microbubble generator 8 is connected to the underflow outlet 72 of the primary vertical shallow purification device 7. The inlet of the secondary vertical wastewater purification equipment is connected to the bottom outlet of the secondary tubular microbubble generator 8; both the primary tubular microbubble generator 6 and the secondary tubular microbubble generator 8 have injection ports connected to the external injection pipeline 4; the top oil outlets 73 of the primary vertical shallow purification equipment 7 and the secondary vertical shallow purification equipment 9 are connected to the external oil phase pipeline 10; the gas phase inlet of the primary tubular microbubble generator 6 and the external gas injection pipeline 3, and the gas phase inlet of the secondary tubular microbubble generator 8 and the external gas injection pipeline 3, have both a conductive state and a blocking state.

[0043] See Figure 1 and Figure 2 As shown, the two treatment units are connected in series via fluid pipelines. Specifically, the oily wastewater to be treated is introduced into the system via the external oily wastewater pipeline 5, first entering the primary tubular microbubble generator 6. After purification by the two treatment units, the qualified clean water is discharged from the system through the treated wastewater outlet 11 at the bottom of the secondary vertical shallow purification device 9. During the separation process, the oil phase separated in the primary vertical shallow purification device 7 and the secondary vertical shallow purification device 9 is collected through the oil discharge pipelines at the top of their respective units and sent to the external oil phase pipeline 10 for transport to subsequent oil recovery or disposal facilities.

[0044] The core control mechanism of this application lies in setting up a gas supply control device for selectively supplying gas to the primary tubular microbubble generator 6 and the secondary tubular microbubble generator 8. Figure 1 In the structure shown, the gas supply control device can be implemented by a set of pipelines and valves. For example, an external gas supply pipeline 3 serves as the main gas source, which branches off into two branches, connected to the gas injection ports of the primary tubular microbubble generator 6 and the secondary tubular microbubble generator 8, respectively.

[0045] As an optional implementation, a first gas injection line valve 1 is provided between the gas phase inlet of the first-stage tubular microbubble generator 6 and the external gas injection pipeline 3. The first gas injection line valve 1 is used to control whether the gas phase inlet of the first-stage tubular microbubble generator 6 and the external gas injection pipeline 3 are in a connected or blocked state. A second gas injection line valve 2 is provided between the gas phase inlet of the second-stage tubular microbubble generator 8 and the external gas injection pipeline 3. The second gas injection line valve 2 is used to control whether the gas phase inlet of the second-stage tubular microbubble generator 8 and the external gas injection pipeline 3 are in a connected or blocked state.

[0046] When the first gas injection line valve 1 is closed, the gas phase inlet of the primary tubular microbubble generator 6 is blocked from the external gas injection pipeline 3, and the primary vertical shallow purification device 7 can be used as a vertical inclined plate oil separator. When the first gas injection line valve 1 is opened, the gas phase inlet of the primary tubular microbubble generator 6 is connected to the external gas injection pipeline 3, and the primary vertical shallow purification device 7 can be used as a vertical shallow air flotation tank. When the second gas injection line valve 2 is closed, the gas phase inlet of the secondary tubular microbubble generator 8 is blocked from the external gas injection pipeline 3, and the secondary vertical shallow purification device 9 can be used as a vertical inclined plate oil separator. When the second gas injection line valve 2 is opened, the gas phase inlet of the secondary tubular microbubble generator 8 is connected to the external gas injection pipeline 3, and the secondary vertical shallow purification device 9 can be used as a vertical shallow air flotation tank.

[0047] By independently controlling the opening and closing of the first gas injection line valve 1 and the second gas injection line valve 2, it is possible to precisely determine whether to inject gas into the corresponding level of tubular microbubble generator. Understandably, this selective gas injection behavior is key to switching the operating modes of the downstream primary vertical shallow purification device 7 or the secondary vertical shallow purification device 9: when a tubular microbubble generator is not injected, its corresponding downstream vertical shallow purification device operates in vertical inclined plate oil separator mode; conversely, when gas is injected, it switches to vertical shallow flotation tank mode.

[0048] As an alternative implementation, see [link to implementation details]. Figure 1 and Figure 2 As shown, the first-stage tubular microbubble generator 6 and the second-stage tubular microbubble generator 8 have the same structure, both including a dissolved gas tube 61 and a dissolved gas release device 62. The bottom of the dissolved gas tube 61 is provided with a dissolved gas outlet pipe 618, which has a dissolved gas water outlet. The dissolved gas water outlet is connected to the first-stage vertical shallow purification device 7 or the second-stage vertical shallow purification device 9 through the dissolved gas release device 62.

[0049] The dissolved gas release device 62 can preferably be a ball valve, allowing adjustment of the dissolved gas pressure by changing the valve opening. This eliminates the risk of clogging and requires no regular maintenance. The injection pipes 615 of the primary tubular microbubble generator 6 and the secondary tubular microbubble generator 8 are connected to the external gas phase pipeline to provide the necessary gas source for the foaming process. The injection volume is 5%–10% of the inlet water flow rate, and the average bubble particle size is less than 50 μm. The injection ports of the primary tubular microbubble generator 6 and the secondary tubular microbubble generator 8 are connected to the external drug delivery pipeline 614. The drug is a flocculant or demulsifier. The structure of the secondary tubular microbubble generator 8 is the same as that of the primary tubular microbubble generator 6.

[0050] As an alternative implementation, see [link to implementation details]. Figure 1 and Figure 2 As shown, the dissolved air pipe 61 includes a straight pipe section 616 and an inner cylinder 617 fixed inside the straight pipe section 616. An outer annular cavity 620 is provided between the inner cylinder 617 and the inner wall of the straight pipe section 616. Part of the fluid injected into the dissolved air pipe 61 can circulate between the inner cylinder 617 and the outer annular cavity 620.

[0051] See Figure 1 and Figure 2 As shown, Figure 2 The arrows in the text indicate the direction of movement of some fluids. The main body of the dissolved air pipe 61, the pressurized straight pipe section 616, is equipped with an inner cylinder 617. The inner cylinder 617 and the circulation cavity can force the formation of circulation, prolong the residence time of bubbles, and improve the dissolved air effect. No regular maintenance is required. The air injection volume is 5%-10% of the inlet water flow rate, and the average particle size of the bubbles is less than 50μm.

[0052] As an optional implementation, the primary tubular microbubble generator 6 and the secondary tubular microbubble generator 8 also include an arc-shaped baffle 619. The arc-shaped baffle 619 is located below the inner cylinder 617, with the concave side of the arc-shaped baffle 619 facing the inner cylinder 617. A flow port is formed between the inner cylinder 617 and the arc-shaped baffle 619.

[0053] As an optional implementation, the primary tubular microbubble generator 6 and the secondary tubular microbubble generator 8 further include a water inlet section with a water inlet 611. A throat 613 is formed in the middle of the water inlet section. The inner diameter of the throat 613 is smaller than the inner diameter of the rest of the water inlet section. A swirl vane 612 is provided in the water inlet section and is located on the upstream side of the throat 613. The throat 613 is also connected to a drug injection pipe 614 and a gas injection pipe 615. The drug injection port is located on the drug injection pipe 614, and the gas phase inlet is located on the gas injection pipe 615.

[0054] Swirl vanes 612 are installed in the water inlet sections of the primary tubular microbubble generator 6 and the secondary tubular microbubble generator 8 to generate initial bubbles through swirling shearing action.

[0055] A radial injection port is provided at the upper throat 613, which can simultaneously carry out jet dissolved gas and drug mixing reaction to achieve nucleation and bubble formation in the floc, which not only reduces the amount of drug consumed, but also significantly enhances the dryness of the floc.

[0056] See Figure 1 and Figure 2 As shown, the primary tubular microbubble generator 6 and the secondary tubular microbubble generator 8 are highly efficient fluid mixing and dissolved air devices. The fluid to be treated enters the device through the inlet 611 and first flows through an inlet section equipped with static swirl vanes 612. These vanes 612 impart strong rotational motion to the fluid, and the shear force generated by the high-speed swirl initially breaks up larger oil droplets in the water, creating favorable hydraulic conditions for subsequent gas-liquid mixing. Subsequently, the rotating fluid enters the constricted throat 613. According to Bernoulli's principle, the fluid velocity increases sharply at the throat 613, while the pressure decreases accordingly, thus forming a local negative pressure zone. In this negative pressure zone, the gas injected through the air injection pipe 615 can be instantly drawn in and sheared into microbubbles by the high-speed water flow. Simultaneously, the chemical agent injected through the chemical injection pipe 614 can also achieve instantaneous and intense mixing with the wastewater here, greatly improving the mixing efficiency.

[0057] After passing through the throat 613, the gas, liquid, and chemical three-phase mixture enters a pressurized dissolved gas straight pipe section 616 with its diameter restored. To further enhance the dissolved gas process and prolong the gas-liquid contact time, this pipe section is equipped with an inner cylinder 617 and an arc-shaped baffle 619. The inner cylinder 617 forces the fluid to form complex circulation and vortices within the pipe, increasing the turbulence and travel of the fluid, ensuring that the gas can be fully dissolved in the water or uniformly dispersed in the form of extremely fine bubbles. This structure allows for the stable generation of microbubbles, laying a solid foundation for efficient air flotation separation. Finally, the fully mixed fluid with dissolved gas flows out through the dissolved gas outlet pipe 618 and enters the downstream vertical shallow-layer purification equipment.

[0058] As an alternative implementation, see [link to implementation details]. Figure 1 and Figure 3 As shown, the first-stage vertical shallow purification device 7 and the second-stage vertical shallow purification device 9 have the same structure, both including an inlet pipe 71, a tank and an inclined plate assembly. The inlet end of the inlet pipe 71 can be connected to the bottom outlet of the first-stage tubular microbubble generator 6 or the second-stage tubular microbubble generator 8, and the outlet end of the inlet pipe 71 is connected to the tank. The inclined plate assembly is located above the outlet of the inlet pipe 71 and is used to coalesce tiny oil droplets and suspended impurities.

[0059] As an alternative implementation, see [link to implementation details]. Figure 1 and Figure 3As shown, the inclined plate assembly includes concentric frustum inclined plates 74. In each group of concentric frustum inclined plates 74, the concentric frustum inclined plates 74 are arranged at intervals along the vertical direction. The spacing between adjacent concentric frustum inclined plates 74 is equal or unequal, and there are channels for fluid flow between adjacent concentric frustum inclined plates 74.

[0060] The tank is equipped with concentric frustum inclined plates 74 with equal or unequal axial spacing, which can increase the separation area and promote oil-water separation through shallow sedimentation. Each set of concentric frustum inclined plates 74 has no less than 5 layers, and the hydraulic residence time of the tank is ≤3min.

[0061] The aforementioned structure of the concentric truncated cone inclined plate 74 significantly increases the effective separation area per unit volume of the equipment, representing a typical application of shallow separation theory. Fluid flows slowly upwards at a low velocity through the channels between adjacent concentric truncated cone inclined plates 74 within the tank. When the equipment operates in gravity separation mode (i.e., without upstream aeration), lower-density oil droplets, under buoyancy, float and accumulate along the inner wall of the inclined plate, eventually converging at the oil collection area at the top of the equipment. When the equipment switches to air flotation separation mode (i.e., with upstream aeration), microbubbles in the water adhere to the flocs formed by chemical flocculation, forming a "gas-solid" composite with a density less than water. These composites also float rapidly along the inner wall of the inclined plate, accumulating at the top to form a scum layer. Both the oil layer and the scum layer can be periodically or continuously discharged through the top oil drain pipe at the top of the equipment, flowing into the external oil phase pipeline 10. The thoroughly separated purified water is discharged from the bottom outlet 72 at the bottom of the equipment. Thanks to its vertical structure and efficient inclined plate components, the hydraulic retention time of this equipment can be controlled within 3 minutes, achieving a balance between high-efficiency treatment and equipment miniaturization.

[0062] As an optional implementation, the water inlet pipe 71 includes a horizontal section and a vertical section connected to each other, wherein: the horizontal section passes through the tank wall in a sealed manner and can be connected to the bottom outlet of the primary tubular microbubble generator 6 or the secondary tubular microbubble generator 8; the vertical section is arranged along the axis of the tank, the outlet of the vertical section is arranged facing the inclined plate assembly, and a flow equalization grid 75 is provided at the outlet of the vertical section.

[0063] The flow equalization grid 75 can evenly distribute the concentrated water flow across the entire cross-section of the tank, avoiding local eddies or short-circuit phenomena caused by water flow impact, and creating an ideal hydraulic environment for subsequent smooth separation.

[0064] Example 2:

[0065] This embodiment provides a method for controlling the treatment of oily wastewater using vertical shallow purification equipment in series. By adjusting the combined state of the first air injection pipeline valve 1 and the second air injection pipeline valve 2, this method can flexibly achieve at least three different overall treatment processes to adapt to varying influent conditions.

[0066] Process Mode 1: Two-stage vertical inclined plate oil separator mode. This mode is suitable for treating wastewater with low oil concentration, large oil droplet size, and easy removal by gravity separation.

[0067] The oil content in the wastewater is detected. When the oil content in the wastewater is less than a first set value, the gas phase inlet of the primary tubular microbubble generator 6 and the external gas injection pipeline 3, as well as the gas phase inlet of the secondary tubular microbubble generator 8 and the external gas injection pipeline 3, are both blocked. Flocculant is added to the primary tubular microbubble generator 6 and the secondary tubular microbubble generator 8 only through the injection port. At this time, the primary tubular microbubble generator 6 and the secondary tubular microbubble generator 8 are used as vertical inclined plate oil separators. The oily wastewater passes sequentially through the primary tubular microbubble generator 6, the primary vertical shallow purification device 7, the secondary tubular microbubble generator 8, and the secondary vertical shallow purification device 9.

[0068] Specifically, firstly, both the first gas injection line valve 1 and the second gas injection line valve 2 are closed, at which point neither of the two-stage tubular microbubble generators functions.

[0069] Then, the oily wastewater enters the inlet 611 of the non-aerated first-stage tubular microbubble generator 6 through the inlet tube bundle, and the flocculant enters through the injection port. After the wastewater and the agent are mixed and reacted, they flow downstream through the bottom drain into the first-stage vertical shallow purification equipment 7, and oil-water separation is carried out under the shallow sedimentation action of the concentric cone inclined plate 74.

[0070] Finally, the separated oil phase flows into the external oil phase pipeline through the top oil drain pipe, while the treated wastewater enters the secondary tubular microbubble generator 8 through the bottom outlet 72 of the tank, where it is mixed and reacted with the reagents again. Then, it flows into the secondary vertical shallow purification device 9 through the bottom drain outlet, where oil and water are separated under the shallow settling action of the concentric cone inclined plate 74. The treated wastewater is connected to the downstream pipeline through the bottom outlet 72, while the oil phase flows into the external oil phase pipeline through the top oil drain outlet 73.

[0071] Process Mode 2: A series connection of a primary vertical inclined plate oil separator and a secondary vertical shallow air flotation tank (air flotation separation). This mode is suitable for treating wastewater of moderate difficulty containing some emulsified oil or fine suspended solids.

[0072] When the oil content in the wastewater is greater than or equal to the first set value and less than or equal to the second set value, the gas phase inlet of the primary tubular microbubble generator 6 is blocked from the external gas injection pipeline 3, while the gas phase inlet of the secondary tubular microbubble generator 8 is open to the external gas injection pipeline 3. Flocculant is added to the primary tubular microbubble generator 6 and the secondary tubular microbubble generator 8 through the injection port, and gas is introduced into the secondary tubular microbubble generator 8 through the gas phase inlet. At this time, the primary tubular microbubble generator 6 is used as a vertical inclined plate oil separator, and the secondary tubular microbubble generator 8 is used as a vertical shallow air flotation tank. The oily wastewater passes sequentially through the primary tubular microbubble generator 6, the primary vertical shallow purification device 7, the secondary tubular microbubble generator 8, and the secondary vertical shallow purification device 9.

[0073] Specifically, firstly, the first gas injection line valve 1 is opened and the second gas injection line valve 2 is closed. At this time, the first-stage tubular microbubble generator 6 does not generate bubbles because there is no gas injection. The first-stage vertical shallow purification equipment 7 is used as a vertical inclined plate oil separator, and the second-stage vertical shallow purification equipment 9 is used as a vertical shallow air flotation tank.

[0074] Then, the oily wastewater enters the inlet 611 of the non-aerated first-stage tubular microbubble generator 6 through the inlet pipe bundle, while the reagent is injected through the radial injection port at the upper throat 613. After the reagent and oily wastewater are mixed and reacted, they flow downstream through the bottom drain port of the pressurized dissolved air pipe 61 into the first-stage vertical shallow purification equipment 7 (acting as a vertical inclined plate oil separator), and oil and water are separated under the shallow sedimentation action of the concentric cone inclined plate 74.

[0075] Finally, after separation by the concentric cone inclined plate 74, the oil phase flows into the external oil phase pipeline through the top discharge pipe, while the treated wastewater is discharged through the bottom outlet 72 of the tank and enters the inlet 611 of the secondary tubular microbubble generator 8. The reagents and gases are injected through the symmetrically arranged injection ports and gas injection ports at the upper throat 613 of the diode-type microbubble generator, and a strengthened dissolved gas and reagent flocculation reaction occurs in the straight section 616 of the main body of the jet dissolved gas pipe 61. The resulting dissolved gas water is released under reduced pressure by the dissolved gas release device 62, generating a large number of microbubbles. Some of these microbubbles nucleate and precipitate from inside the flocs and tightly adhere to them. The wastewater mixed with microbubbles and flocs enters the secondary vertical shallow purification equipment 9 (acting as a vertical shallow air flotation tank) for air flotation purification. The wastewater purified by air flotation is connected to the downstream system pipeline through the bottom outlet 72, while the separated oil phase flows into the external oil phase pipeline through the top discharge pipe.

[0076] Process Mode 3: Two-stage vertical shallow air flotation tank series mode, i.e., two-stage air flotation separation mode. This mode is specifically designed for treating wastewater with poor water quality, such as wastewater with high oil concentration, severe emulsification, and high suspended solids content.

[0077] When the oil content in the wastewater exceeds the second set value, the gas phase inlet of the primary tubular microbubble generator 6 and the external gas injection pipeline 3, as well as the gas phase inlet of the secondary tubular microbubble generator 8 and the external gas injection pipeline 3, are both kept in a conductive state. Flocculant is added to the primary tubular microbubble generator 6 and the secondary tubular microbubble generator 8 through the injection port, and gas is introduced into both the primary tubular microbubble generator 6 and the secondary tubular microbubble generator 8 through the gas phase inlet. At this time, the primary tubular microbubble generator 6 and the secondary tubular microbubble generator 8 are used as vertical shallow flotation tanks. The oily wastewater passes sequentially through the primary tubular microbubble generator 6, the primary vertical shallow purification device 7, the secondary tubular microbubble generator 8, and the secondary vertical shallow purification device 9.

[0078] Specifically, firstly, both the first gas injection line valve 1 and the second gas injection line valve 2 are opened. At this time, both tubular microbubble generators are in operation, and both vertical shallow purification devices are used as vertical shallow air flotation tanks.

[0079] Then, the wastewater enters the inlet 611 of the first-stage tubular microbubble generator 6 through the inlet pipe bundle. The reagents and gases are injected through the symmetrically arranged injection ports and gas injection ports at the upper throat 613 of the first-stage tubular microbubble generator 6. The enhanced dissolved gas and reagent flocculation reaction occurs in the straight section 616 of the jet dissolved gas pipe 61. The dissolved gas water generated is released by the dissolved gas release device 62 after depressurization, generating a large number of microbubbles. Some microbubbles nucleate and precipitate from the inside of the flocs and tightly adhere to the flocs. The wastewater mixed with microbubbles and flocs enters the first-stage vertical shallow purification equipment (acting as a vertical shallow air flotation tank) for air flotation purification treatment.

[0080] Finally, the oil phase separated by the concentric cone inclined plate 74 flows into the external oil phase pipeline through the top oil drain pipe, while the wastewater enters the secondary tubular microbubble generator 8 through the bottom outlet 72 of the tank, where it undergoes enhanced dissolved air and flocculation reactions with the gas and reagents. The resulting dissolved air water is then released under reduced pressure by the dissolved air release device 62, generating a large number of microbubbles. Some of these microbubbles nucleate and precipitate from inside the flocs and tightly adhere to them. The wastewater mixed with microbubbles and flocs enters the secondary vertical shallow purification device 9 (acting as a vertical shallow air flotation tank) for air flotation purification. The treated wastewater is connected to the downstream pipeline through the bottom outlet 72 of the tank, while the separated oil phase flows into the external oil phase pipeline through the top oil drain pipe of the tank.

[0081] In summary, this embodiment achieves flexible switching between multiple process modes with a single device by combining and controlling the gas supply to the two-stage treatment units, greatly enhancing the system's adaptability to different influent conditions. Furthermore, the preferred equipment structure in this embodiment ensures the overall compactness and high efficiency of the system.

[0082] The specific features, structures, or characteristics described in this specification may be combined in any suitable manner in one or more embodiments or examples.

[0083] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0084] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for regulating the treatment of oily wastewater using vertical shallow purification devices in series operation, characterized in that, An oily wastewater treatment device using vertical shallow purification equipment connected in series, comprising a primary tubular microbubble generator, a primary vertical shallow purification unit, a secondary tubular microbubble generator, and a secondary vertical shallow purification unit, wherein: The inlet of the first-stage tubular microbubble generator is connected to the external oily wastewater pipeline; the inlet of the first-stage vertical shallow purification equipment is connected to the bottom outlet of the first-stage tubular microbubble generator; the inlet of the second-stage tubular microbubble generator is connected to the bottom outlet of the first-stage vertical shallow purification equipment; and the inlet of the second-stage vertical shallow purification equipment is connected to the bottom outlet of the second-stage tubular microbubble generator. Both the primary tubular microbubble generator and the secondary tubular microbubble generator have injection ports that are connected to the external drug delivery pipeline, and the top oil outlets of both the primary vertical shallow purification equipment and the secondary vertical shallow purification equipment are connected to the external oil delivery pipeline. The gas phase inlet of the first-stage tubular microbubble generator and the external gas injection pipeline, as well as the gas phase inlet of the second-stage tubular microbubble generator and the external gas injection pipeline, both have a conductive state and a blocking state. A first gas injection line valve is provided between the gas phase inlet of the first-stage tubular microbubble generator and the external gas injection pipeline. The first gas injection line valve is used to control whether the gas phase inlet of the first-stage tubular microbubble generator and the external gas injection pipeline are in a conducting state or a blocking state. A second gas injection line valve is provided between the gas phase inlet of the two-stage tubular microbubble generator and the external gas injection pipeline. The second gas injection line valve is used to control whether the gas phase inlet of the two-stage tubular microbubble generator and the external gas injection pipeline are in a conducting state or a blocking state. The method includes: When the oil content in the wastewater is less than a first set value, the gas phase inlet of the primary tubular microbubble generator and the external gas injection pipeline, as well as the gas phase inlet of the secondary tubular microbubble generator and the external gas injection pipeline, are both blocked. Flocculant is added to the primary and secondary tubular microbubble generators only through the injection port. At this time, both the primary vertical shallow purification device and the secondary vertical shallow purification device are used as vertical inclined plate oil separators. When the oil content in the wastewater is greater than or equal to the first set value and less than or equal to the second set value, the gas phase inlet of the primary tubular microbubble generator is controlled to be in a blocked state with the external gas injection pipeline, and the gas phase inlet of the secondary tubular microbubble generator is controlled to be in a conductive state with the external gas injection pipeline. Flocculant is added to the primary tubular microbubble generator and the secondary tubular microbubble generator through the injection port, and gas is introduced into the secondary tubular microbubble generator through the gas phase inlet. At this time, the primary vertical shallow purification equipment is used as a vertical inclined plate oil separator, and the secondary vertical shallow purification equipment is used as a vertical shallow air flotation tank. When the oil content in the wastewater exceeds the second set value, the gas phase inlet of the primary tubular microbubble generator and the external gas injection pipeline, as well as the gas phase inlet of the secondary tubular microbubble generator and the external gas injection pipeline, are both kept in a conductive state. Flocculant is added to both the primary and secondary tubular microbubble generators through the injection port, and gas is introduced into both the primary and secondary tubular microbubble generators through the gas phase inlet. At this time, both the primary and secondary vertical shallow purification devices are used as vertical shallow flotation tanks. The oily wastewater is passed sequentially through a primary tubular microbubble generator, a primary vertical shallow purification device, a secondary tubular microbubble generator, and a secondary vertical shallow purification device.

2. The method for controlling the treatment of oily wastewater by series combination operation of vertical shallow purification equipment according to claim 1, characterized in that, The primary tubular microbubble generator and the secondary tubular microbubble generator have the same structure, both including a dissolved gas tube and a dissolved gas releaser. The bottom of the dissolved gas tube is provided with a dissolved gas water outlet pipe, which has a dissolved gas water outlet. The dissolved gas water outlet is connected to the primary vertical shallow purification device or the secondary vertical shallow purification device through the dissolved gas releaser.

3. The method for controlling the treatment of oily wastewater by series combination operation of vertical shallow purification equipment according to claim 2, characterized in that, The dissolved air pipe includes a straight pipe section and an inner cylinder fixed inside the straight pipe section. An outer annular cavity is provided between the inner cylinder and the inner wall of the straight pipe section. Part of the fluid injected into the dissolved air pipe can circulate between the inner cylinder and the outer annular cavity.

4. The method for controlling the treatment of oily wastewater by series combination operation of vertical shallow purification equipment according to claim 3, characterized in that, The primary tubular microbubble generator and the secondary tubular microbubble generator further include an arc-shaped baffle. The arc-shaped baffle is located below the inner cylinder, with its concave side facing the inner cylinder. A flow port is formed between the inner cylinder and the arc-shaped baffle.

5. The method for controlling the treatment of oily wastewater by series combination operation of vertical shallow purification equipment according to claim 2, characterized in that, The primary tubular microbubble generator and the secondary tubular microbubble generator further include a water inlet section with a water inlet. A throat is formed in the middle of the water inlet section. The inner diameter of the throat is smaller than the inner diameter of the rest of the water inlet section. A swirl vane is provided in the water inlet section, and the swirl vane is located on the upstream side of the throat. The throat tube is also connected to a drug injection tube and a gas injection tube, with the drug injection port located on the drug injection tube and the gas phase inlet located on the gas injection tube.

6. The method for controlling the treatment of oily wastewater by series combination operation of vertical shallow purification equipment according to claim 1, characterized in that, The primary vertical shallow purification equipment and the secondary vertical shallow purification equipment have the same structure, both including an inlet pipe, a tank, and an inclined plate assembly, wherein: The inlet end of the water inlet pipe can be connected to the bottom outlet of the first-stage tubular microbubble generator or the second-stage tubular microbubble generator, and the outlet end of the water inlet pipe is connected to the tank body. The inclined plate assembly is located above the outlet of the water inlet pipe and is used to coalesce tiny oil droplets and suspended impurities.

7. The method for controlling the treatment of oily wastewater by series combination operation of vertical shallow purification equipment according to claim 6, characterized in that, The inclined plate assembly includes concentric frustum inclined plates. In each group of concentric frustum inclined plates, the concentric frustum inclined plates are arranged at intervals along the vertical direction. The spacing between adjacent concentric frustum inclined plates is equal or unequal, and there is a channel for fluid flow between adjacent concentric frustum inclined plates.

8. The method for controlling the treatment of oily wastewater by series combination operation of vertical shallow purification equipment according to claim 6, characterized in that, The water inlet pipe includes a connected horizontal section and a vertical section, wherein: The horizontal section is sealed and passes through the tank wall of the tank body, and can be connected to the bottom outlet of the primary tubular microbubble generator or the secondary tubular microbubble generator; The vertical section is arranged along the axis of the tank body, the outlet of the vertical section is arranged towards the inclined plate assembly, and a flow equalization grid is provided at the outlet of the vertical section.

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