A positive and negative pressure cycle pulse vibrating screen and working method

Abstract

The present invention relates to a positive and negative pressure cycle pulse vibrating screen and a working method, comprising a frame, in which a vibrating screen is fixed, the vibrating screen comprising a vibrating motor, a screen bed, and a screen mesh, a feeding mechanism being correspondingly provided on the top of the vibrating screen, and a liquid-gas separation mechanism being connected at the bottom thereof for smoothly discharging the liquid, and an air source for suction and exhaust being installed on the frame, the exhaust port and the intake port of the air source being respectively connected to the positive and negative pressure interfaces of a positive and negative pressure pulse airflow control mechanism, the positive and negative pressure pulse airflow control mechanism forming an airflow passage with the screen surface of the screen mesh through a connecting mechanism and controlling the duration and time interval of the positive and negative pressures, the negative pressure pulse airflow flowing from the top of the screen to the bottom of the screen, and the positive pressure pulse airflow flowing from the bottom of the screen to the top of the screen; pressure regulating and gas releasing devices are both provided at the intake port and the exhaust port of the air source, the vibrating motor is connected to a frequency conversion device, and the air control system is further included at one side of the frame, and its control lines are respectively connected to corresponding electrical equipment.

Description

Technical Field

[0001] The invention relates to drilling fluid screening and processing equipment, in particular to a positive and negative pressure circulation pulse vibrating screen and a working method thereof. Background Art

[0002] Modern drilling places extremely high demands on drilling fluid performance and environmental protection. While meeting the performance requirements of drilling machinery, environmental protection, safety, and occupational health must also be met. Solid impurities (especially fine impurities) in drilling fluid must be promptly removed for recycling. Excessive solids content in drilling fluid poses a significant threat to downhole safety, often leading to pipe sticking. The forced discharge of high-solids waste drilling fluid from the system poses a serious threat to workers and the environment, while also increasing the loss of drilling fluid material.

[0003] Solids control systems and equipment used to recycle drilling fluids (hereafter referred to as solids control equipment) are becoming increasingly complex, with lengthy processes and high energy consumption. Solids control equipment also produces large amounts of waste, with waste cuttings and drilling fluids containing high levels of water and complex chemical compositions. To prevent pollution, complex waste disposal systems are required, further increasing energy consumption and floor space.

[0004] Drilling solids control systems typically have four levels of processing equipment: vibrating screens, desanders, desilters, and centrifuges. Vibrating screens are the primary processing equipment. Due to their operating principle and design, when high-viscosity drilling fluid is encountered, the screen mesh quickly clogs (a phenomenon known as screen sticking), resulting in significant slurry loss. This causes abnormal drilling fluid consumption and environmental pollution, and slurry sticking accelerates screen damage. Instantaneous high-flow conditions can also lead to significant slurry loss due to insufficient vibrating screen capacity. Because vibrating screens, as primary processing equipment, are used only for coarse separation, drilling fluid with high sand content quickly forms a large amount of sediment after entering the storage tank. This necessitates the regular discharge of high-sand drilling fluid from the tank, further causing pollution and waste.

[0005] Under existing technical conditions, in order to improve the system's processing capacity, the only option is to continuously increase the configuration and quantity of equipment, and keep the high-energy-consuming second, third, and fourth-level treatment equipment (i.e., desanders, desilters, and centrifuges) running for a long time. This makes the drilling fluid solid phase control system and equipment configuration more complex, increases the number, increases energy and material consumption, increases waste emissions, and increases the load on environmental protection facilities used for harmless treatment of drilling waste. The above unfavorable factors directly lead to increased drilling costs and indirectly lead to increased risks such as equipment failure, downhole accidents, and safety and environmental protection.

[0006] In order to improve the equipment's processing capacity and separation efficiency, existing drilling vibrating screens, in addition to single-layer screen structures, also have double-layer and triple-layer structures. The increase in screen area increases the processing capacity, but because the working principle has not changed, when faced with complex working conditions such as high viscosity and large flow, there are still problems with screen sticking and slurry leakage; the waste after separation has a high moisture content, making subsequent harmless treatment difficult; the multi-layer structure increases the consumption of vulnerable parts such as screens and sealing strips, and the lower screen is not easy to observe and replace. Once damaged, it cannot be maintained in time, causing construction accidents. In addition, some vibrating screens are installed with a vacuum funnel and a vacuum device at the bottom of the screen at the chip discharge end. This reduces the moisture content of the discharged drill cuttings and can recover some drilling fluid. However, when faced with complex and special working conditions, they have the same problems as conventional vibrating screens. Moreover, the screen working in a vacuum state for a long time is more prone to clogging and wear. Therefore, the vacuum device of this type of vibrating screen is turned on intermittently to avoid screen clogging. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a positive and negative pressure circulating pulse vibrating screen and a working method, which can effectively cope with complex working conditions such as high-viscosity drilling fluid and instantaneous large flow. The screen will not be blocked during long-term operation, and it still has a large processing capacity when a high-mesh screen is installed. It has a separation accuracy comparable to that of a desilter and a higher separation efficiency. It can replace the first, second, and third-stage processing equipment in conventional drilling solid phase control systems, simplify system configuration, reduce energy consumption, material consumption, and operation and maintenance difficulty, solve the problem of large-scale waste discharge, and recover drilling fluid to the greatest extent. The dried drilling waste is convenient for subsequent harmless treatment, reducing the risk of pollution.

[0008] In order to achieve the above technical objectives, the present invention adopts and provides a positive and negative pressure circulating pulse vibrating screen, including a frame, in which a vibrating screen is fixed, the vibrating screen mainly includes a vibrating motor, a screen bed, and a screen mesh, a feeding mechanism is correspondingly provided on the vibrating screen, and a liquid-gas separation mechanism is connected below to discharge the liquid smoothly, and also includes a suction and exhaust dual-purpose air source installed on the frame, the exhaust port and the intake port of the air source are respectively connected to the positive and negative pressure interfaces of the positive and negative pressure pulse airflow control mechanism, the positive and negative pressure pulse airflow control mechanism forms an airflow path with the screen surface of the screen mesh through a connecting mechanism and controls the duration and time interval of the positive and negative pressures, the negative pressure pulse airflow flows from the top of the screen to the bottom of the screen, and the positive pressure pulse airflow flows from the bottom of the screen to the top of the screen; the intake port and the exhaust port of the air source are both provided with pressure regulating and gas releasing devices, the vibrating motor is connected to the frequency conversion device, and also includes an electric control system located on one side of the frame, the control lines of which are respectively connected to the corresponding electrical equipment and used to adjust the parameters of the electrical equipment.

[0009] Preferably, there are multiple air flow paths, each corresponding to an independent working area on the screen; each corresponding air flow path in the positive and negative pressure pulse airflow control mechanism is provided with a positive and negative pressure conversion mechanism. In one pulse cycle, only one air flow path is a positive pressure airflow within a certain period of time according to the order of the air flow path positions, and the remaining air flow paths are negative pressure airflow paths. The positive and negative pressure airflows in the independent working areas of the screen work periodically in a cycle.

[0010] Preferably, the sieve is sealed and fixed on the sieve bed. The sieve bed divides the sieve into multiple independent working areas, each of which is connected to the liquid-gas separation mechanism. From top to bottom, the sieve bed area corresponding to each independent working area of ​​the sieve and the internal area of ​​the liquid-gas separation mechanism form an independently sealed liquid-gas flow channel; the air flow path is correspondingly connected to the liquid-gas flow channel.

[0011] The present invention provides a working method of a positive and negative pressure circulation pulse vibrating screen, which is applied to the above-mentioned positive and negative pressure circulation pulse vibrating screen, comprising: the drilling fluid to be processed first enters the feeding tank, and flows downwardly onto the upper surface of the tail screen of the composite screen through the feeding port on the feeding tank; the vibrating body generates an exciting force under the excitation action of the vibration motor to cause the drilling fluid and the solid phase therein to move forward; the air pump is turned on, and the air intake port of the air pump is connected to the negative pressure channel of the positive and negative pressure pulse airflow generator, and the exhaust port is connected to the positive pressure channel of the positive and negative pressure pulse airflow generator; the positive and negative pressure pulse airflow generator and the screen form n airflow channels, and a positive high-speed airflow is generated on the screen surface corresponding to the negative pressure airflow to continuously carry the drilling fluid on the screen surface through the screen, and a negative high-speed airflow is generated on the screen surface corresponding to the positive pressure airflow The high-speed airflow blows up the drill cuttings and sweeps the mesh to clean and regenerate them. In one pulse cycle, only one airflow channel is positive pressure airflow for a certain period of time, which circulates in the order of the airflow channel positions, so that the mesh area corresponding to the positive pressure airflow moves forward in a cycle, and the drill cuttings are transported forward out of the machine with the forward throwing force generated by the vibration of the vibrating screen; the drilling fluid that passes through the screen enters the screen bed together with the high-speed airflow, and enters the liquid-gas separation chamber through the liquid-gas outlet at the bottom of the screen bed. The drilling fluid settles at the bottom of the liquid-gas separation chamber, and finally flows over the water-sealed weir plate out of the machine, while the gas flows upward in the fixed liquid-gas flow channel, enters the negative pressure channel of the positive and negative pressure pulse airflow generator through the connecting pipe, and is finally sucked into the air pump through the negative pressure connecting pipe.

[0012] The beneficial effects of the present invention are: it no longer relies on the high-frequency and large-amplitude vibrations generated by the vibrating screen itself for screening to obtain materials on and under the screen, but instead drives material separation through high-speed pulse airflow with alternating positive and negative pressure cycles. Under the condition of installing a high-mesh screen, it still has a large processing capacity, is not easy to stick to the screen and the slurry runs, the screen has a long service life, and has high dehydration efficiency. The transportation of the material on the screen is completed by the lifting effect of the positive pressure airflow and the forward throwing force generated by the vibration. Unlike relying solely on high-frequency vibration, it can effectively slow down the wear of the screen by the material on the screen.

[0013] The negative pressure pulse airflow in the positive and negative pressure circulating pulse airflow flows from above the screen to below the screen, and the gas and liquid materials on the screen and the materials smaller than the mesh size are carried by the high-speed airflow and quickly pass through the screen below the screen; the positive pressure pulse airflow flows from below the screen to above the screen, and the materials on the screen that cannot pass through the screen are quickly blown up, thereby realizing material separation; the mesh surface is divided into several working areas, corresponding to the same number of airflow channels, and each working area works alternately with positive pressure airflow and negative pressure airflow; the several working areas of the mesh surface are divided into two states according to the positive and negative pressure airflows, namely positive pressure state and negative pressure state, and these two states change periodically, and the number and duration of positive pressure state and negative pressure state operate in a certain proportion to maintain an efficient and stable working state. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a general schematic diagram of the positive and negative pressure cycle pulse vibrating screen of the embodiment;

[0015] Figure 2 Schematic diagram of the rack structure in the embodiment;

[0016] Figure 3 This is a schematic diagram of the installation of the composite screen and the frame in the embodiment;

[0017] Figure 4 Schematic diagram of the composite screen structure in the embodiment;

[0018] Figure 5 Schematic diagram of the vibration box structure in the embodiment;

[0019] Figure 6 This is a schematic diagram of the installation of positive and negative pressure airflow pipelines in the embodiment;

[0020] Figure 7 Schematic diagram of the liquid-gas separation chamber structure in the embodiment;

[0021] Figure 8 This is the section BB in the structural diagram of the liquid-gas separation chamber in the embodiment;

[0022] Figure 9 Schematic diagram of the combined structure of the sieve bed and the screen in the embodiment;

[0023] Figure 10 This is the section AA in the schematic diagram of the combined structure of the sieve bed and the screen mesh in the embodiment;

[0024] Figure 11 Schematic diagram of the structure of the positive and negative pressure pulse airflow generator in the embodiment;

[0025] Figure 12 It is the cross section DD in the structural schematic diagram of the positive and negative pressure pulse airflow generator in the embodiment;

[0026] Figure 13 Schematic diagram of the electronic control system in the embodiment;

[0027] Figure 14 Schematic diagram of the working state of the screen in the embodiment;

[0028] In the figure: 1. frame, 2. composite screen, 3. air pump mounting bracket, 4. air pump, 5. positive and negative pressure pulse air flow generator, 6. feeding tank, 7. electronic control system, 8. screen surface inclination adjustment device, 9. composite screen mounting sleeve, 10. adjustment device mounting seat, 11. adjustment device mounting ear, 12. composite screen mounting pin, 13. adjustment device connecting ear seat, 14. adjustment device connecting rod, 15. adjustment device mounting seat, 16. vibration box, 17. suspension vibration isolator, 18. vibration motor, 19. screen, 20. sieve bed, 21. vibration isolator rear support, 22. liquid-gas separation chamber, 23. vibration isolator front support, 24. box, 25. reinforcement cross brace, 26. sieve bed mounting seat, 27. vibration motor mounting beam, 28. One-phase connecting pipe, 29. Two-phase connecting pipe, 30. Three-phase connecting pipe, 31. Four-phase connecting pipe, 32. Five-phase connecting pipe, 33. Six-phase connecting pipe, 34. Positive pressure connecting pipe, 35. Negative pressure connecting pipe, 36. Separation chamber body, 37. Water-sealed weir plate, 38. Separation chamber partition, 39. Separation chamber sieve bed connecting sleeve, A1. One-phase liquid and gas flow channel, A2. Two-phase liquid and gas flow channel, A3. Three-phase liquid and gas flow channel, A4. Four-phase liquid and gas flow channel, A5. Five-phase liquid and gas flow channel, A6. Six-phase liquid and gas flow channel, B1, one-phase sieve bed interface, B2, two-phase sieve bed interface, B3, three-phase sieve bed interface, B4, four-phase sieve bed interface, B5, five-phase sieve bed interface, B6, six-phase sieve bed interface, 40, liquid-gas outlet, 41, sieve bed frame, 42, shell, 43, positive and negative pressure conversion valve core, 44, push-pull actuator, 45, right end cover, 46, positive pressure channel, 47, negative pressure channel, 48, sealing gasket, 49, generator output connector, 50, negative pressure regulating pressure relief valve, 51, positive pressure regulating pressure relief valve, 52, left end cover, C1, one-phase generator outlet, C2, two-phase generator outlet, C3, three-phase generator outlet, C4, four-phase generator outlet, C5, five-phase generator outlet, C6, six-phase generator outlet, 53, conversion valve disc, 54, conversion valve core sleeve, 55, axial sealing ring, 56, compression Spring, 57, spring seat, 58, positive pressure interface, 59, negative pressure interface, M1, front end vibration motor terminal group, M2, rear end vibration motor terminal group, M3, screen surface inclination adjustment device motor terminal group, M4, air pump motor terminal group, FR3, thermal relay, KM1, screen surface inclination adjustment device motor forward control contactor, KM2, screen surface inclination adjustment device motor reverse control contactor, KM3, air pump motor control contactor, BPQ, vibration motor control inverter, KZQ, pulse airflow generation controller, QF1, vibration motor control circuit breaker, QF2, screen surface inclination adjustment device motor control circuit breaker, QF3, air pump motor control circuit breaker, QF4, pulse airflow generation controller circuit breaker, F1, one phase terminal, F2, two phase terminals, F3, three phase terminals, F4, four phase terminals,F5, five-phase terminal, F6, six-phase terminal, Z1, one-phase screen working state, Z2, two-phase screen working state, Z3, three-phase screen working state, Z4, four-phase screen working state, Z5, five-phase screen working state, Z6, six-phase screen working state, 0, one-phase screen working state start time, t1, two-phase screen working state start time, t2, three-phase screen working state start time, t3, four-phase screen working state start time, t4, five-phase screen working state start time, t5, six-phase screen working state start time, T, one pulse cycle, X, positive pressure state working area, Y, negative pressure state working area. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not intended to limit the scope of the present invention. In the description of the present invention, it should be noted that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "inside", "outside" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the devices or elements referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the present invention. In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, they can be fixedly connected, detachably connected, or integrally connected; they can be mechanically connected or electrically connected; they can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific circumstances.

[0030] The purpose of the present invention is to provide a positive and negative pressure circulating pulse vibrating screen, which can effectively cope with complex working conditions such as high-viscosity drilling fluid and instantaneous large flow. The screen will not be blocked (i.e., the screen will become sticky) during long-term operation. It can still have a large processing capacity when a high-mesh screen is installed. It has a separation accuracy comparable to that of a desilter and a higher separation efficiency. It can replace the first, second, and third-stage processing equipment in conventional drilling solid phase control systems, simplify system configuration, reduce energy consumption, material consumption, and operation and maintenance difficulty, solve the problem of large-scale waste discharge, and recover drilling fluid to the greatest extent. The dried drilling waste is convenient for subsequent harmless treatment, reducing the risk of pollution.

[0031] The traditional vibrating screen only relies on the acceleration of the screen surface to separate solids and liquids, and only relies on high-frequency vibration to generate forward throwing force to transport drill cuttings outward. The separation principle of the present invention is essentially different from that of conventional vibrating screens, that is, the drilling fluid is carried through the screen quickly by the positive high-speed airflow, and the drill cuttings are instantly separated from the screen surface by the reverse high-speed airflow. The positive and reverse high-speed airflows circulate alternately according to a certain period and time ratio, continuously allowing the drilling fluid to pass through the screen quickly and allowing the drill cuttings to jump off the screen surface in time, reducing the wear of the screen. At the same time, the reverse high-speed airflow continuously blows the mesh, completely solving the problem of screen sticking. The vibration of the vibrating screen itself adopts high and low frequency control. During normal operation, low-frequency vibration is turned on, which only needs to provide the function of assisting in transporting drill cuttings outward. High-frequency vibration is no longer relied on to achieve material separation, which can effectively extend the service life of the equipment and screen. When used as a conventional vibrating screen, the air source can be turned off and high-frequency vibration can be turned on.

[0032] like Figure 1 、 Figure 2 、 Figure 3 As shown, the vibrating screen driven by positive and negative pressure circulating pulse airflow is mainly composed of a frame 1, a composite screen 2, an air pump mounting bracket 3, an air pump 4, a positive and negative pressure pulse airflow generator 5, a feeding tank 6, an electronic control system 7, a screen surface inclination adjustment device 8 and other components.

[0033] The frame 1 is welded from rectangular tubing or other cross-section steel and steel plates. The composite screen 2 is mounted within the frame 1. The composite screen mounting sleeve 9 is fixedly mounted on the inner side of the rear end of the frame 1 and also fixedly mounted on the corresponding position of the composite screen 2. They are connected and rotated together by the composite screen mounting pin 12. Adjustment device connecting lugs 13 are fixedly mounted on both sides of the lower middle portion of the composite screen 2. They are hingedly connected to the adjustment device connecting rod 14. The other end of the adjustment device connecting rod 14 is hingedly connected to the screen surface inclination adjustment device 8. The screen surface inclination adjustment device 8 is hingedly connected to the frame 1 via the adjustment device mounting bracket 15. The air pump mounting bracket 3 is mounted on the upper middle portion of the frame 1. The air pump 4 is mounted above the air pump mounting bracket 3. The feed tank 6 is a box-shaped structure and is mounted on the upper rear side of the frame 1. It has a feed port facing downward toward the rear screen of the composite screen 2. The positive and negative pressure pulse airflow generator 5 is mounted on the upper portion of the feed tank. The control box of the electronic control system 7 is mounted on the side of the rear end of the frame 1, and the control cables are connected to the corresponding electrical equipment.

[0034] like Figure 1 、 Figure 4 、 Figure 5 As shown, the composite screen 2 is mainly composed of a vibration box 16, a suspension vibration isolator 17, a vibration motor 18, a screen 19, a screen bed 20, a vibration isolator rear support 21, a liquid-gas separation chamber 22, and a vibration isolator front support 23.

[0035] The vibration box 16 is mainly welded into a whole by a box 24, a reinforcing crossbeam 25, a sieve bed mounting seat 26, and a vibration motor mounting beam 27. A vibration motor 18 is fixedly mounted on the vibration motor mounting beam 27 of the vibration box 16.

[0036] The sieve bed 20 has a built-in metal frame and is covered with elastic non-metallic material. It is fixedly mounted on the sieve bed mounting seat 26 of the vibration box 16.

[0037] The screen 19 is pressed and fixed on the sieve bed 20, and a seal is formed between the contact surfaces of the screen 19, the sieve bed 20 and the sieve bed mounting base 26.

[0038] The suspended vibration isolators 17 are fixedly installed at the four corners outside the vibration box 16 and are divided into four groups. The other end is fixedly installed on the rear support 21 and the front support 23 of the vibration isolator. The rear support 21 and the front support 23 of the vibration isolator are fixedly installed at the four corners outside the liquid-gas separation chamber 22.

[0039] The vibration box 16, the vibration motor 18, the screen 19 and the screen bed 20 together constitute a parametric body. The parametric body can achieve free vibration through elastic support provided by the suspension vibration isolator 17.

[0040] like Figures 6 to 12 As shown, an embodiment of generating positive and negative pressure pulse airflow and using it to drive solid-liquid two-phase separation is described.

[0041] The liquid-gas separation chamber 22 primarily consists of a separation chamber housing 36, a separation chamber partition 38, and a separation chamber sieve bed connection sleeve 39. The separation chamber housing 36 is a box-like structure with an opening on one side. The interior is divided into six compartments by the separation chamber partition 38. The lower edge of the separation chamber partition 38 is spaced a certain distance from the bottom of the housing, allowing the lower portions of each of the six compartments to communicate with the housing's lateral opening. The lateral opening is rectangular, and a water-sealing weir plate 37 is installed in the lower half of the rectangular opening. The upper edge of the water-sealing weir plate 37 is higher than the lower edge of the separation chamber partition 38. When the housing is filled with drilling fluid, the drilling fluid floods the separation chamber partition 38, forming six sealed compartments (i.e., six phase liquid and gas flow channels) and can flow over the water-sealing weir plate 37 and out of the machine. The rear end of the separation chamber housing 36 bulges upward, and at its highest point, a pipe for external connection is led upward from each of the six phase liquid and gas flow channels.

[0042] Separation chamber sieve bed connection sleeves 39 are uniformly distributed above the one-phase liquid and gas flow channel A1, the two-phase liquid and gas flow channel A2, the three-phase liquid and gas flow channel A3, the four-phase liquid and gas flow channel A4, the five-phase liquid and gas flow channel A5, and the six-phase liquid and gas flow channel A6, in a number of groups (four groups in this embodiment, but not limited to four) equal to the number of sieve beds 20. From left to right, one separation chamber sieve bed connection sleeve 39 is located on each of the six phase liquid and gas flow channels to form a group of six separation chamber sieve bed connection sleeves 39, each group of six being paired and sealedly connected to the six liquid-gas outlets 40 on the sieve beds 20.

[0043] The sieve bed 20 comprises a sieve bed frame 41 coated with a non-metallic elastic material. The sieve bed frame 41 is a welded metal structure formed of angle steel forming a rectangular perimeter. Five flat steel bars are evenly spaced along the width of the rectangular perimeter, and several small flat steel bars are evenly spaced along the length as reinforcement ribs. The non-metallic elastic material coating forms six channels along the width of the rectangular perimeter. Each channel has a liquid and gas outlet 40 at the bottom of the sieve bed. There are four sieve beds 20, and four screens 19 are compacted and sealed and mounted on the four sieve beds 20. Each screen 19 is divided into six corresponding working areas.

[0044] The upper surface of the sieve bed 20 is used for sealing and installing the sieve 19. A sieve bed interface is provided on each channel. One sieve bed corresponds to six sieve bed interfaces, and four sieve beds correspond to 24 sieve bed interfaces. The sieve bed interfaces correspond to connecting liquid and gas flow channels.

[0045] The liquid-gas outlets 40 on the six channels correspond to the six-phase liquid-gas flow channels of the liquid-gas separation chamber 22 and are arranged as follows: one-phase sieve bed interface B1 and one-phase liquid-gas flow channel A1, two-phase sieve bed interface B2 and two-phase liquid-gas flow channel A2, three-phase sieve bed interface B3 and three-phase liquid-gas flow channel A3, four-phase sieve bed interface B4 and four-phase liquid-gas flow channel A4, five-phase sieve bed interface B5 and five-phase liquid-gas flow channel A5, and six-phase sieve bed interface B6 and six-phase liquid-gas flow channel A6. Correspondingly, four sieves 19 are compacted and sealed and mounted on the four sieve beds 20. Each sieve 19 is divided into six corresponding working areas.

[0046] The positive and negative pressure pulse airflow generator 5 is composed of a shell 42, a positive and negative pressure conversion valve core 43, a push-pull actuator 44, a right end cover 45, a sealing gasket 48, a generator output connector 49, a negative pressure regulating pressure relief valve 50, a positive pressure regulating pressure relief valve 51, and a left end cover 52.

[0047] There are two through-hole channels in the housing 42, namely a positive pressure channel 46 and a negative pressure channel 47. Each channel has an external interface, namely a positive pressure interface 58 and a negative pressure interface 59.

[0048] The air pump 4 has two interfaces, namely an air intake port and an air exhaust port. The air intake port of the air pump 4 is connected to the negative pressure interface 59 through a negative pressure connecting pipe 35, and the air exhaust port of the air pump 4 is connected to the positive pressure interface 58 through a positive pressure connecting pipe 34.

[0049] The left end face of the shell 42 is sealed with a left end cover 52 , on which a negative pressure regulating relief valve 50 and a positive pressure regulating relief valve 51 are sealed, corresponding to the negative pressure channel 47 and the positive pressure channel 46 respectively. The right end face of the shell 42 is sealed with a right end cover 45 .

[0050] Six through holes are evenly distributed on one side of the shell 42, and six through holes are also evenly distributed on the other side and on the inner wall between the positive pressure channel 46 and the negative pressure channel 47, forming six groups of three-hole coaxial structures, respectively called upper hole, lower hole, and middle hole. Six push-pull actuators 44 are evenly installed on the plane on one side of the upper hole of the shell 42. The push-pull actuator 44 can perform two actions of pushing and pulling back according to the electric control signal. Its structure can be any form such as pneumatic, electric, hydraulic, and mechanical linkage; six generator output connectors 49 are evenly installed on the plane on one side of the lower hole of the shell 42, and the sealing gasket 48 is pressed and fixed in the lower hole by the generator output connector 49. The six generator output connectors 49 are connected to the first phase generator outlet C1, the second phase generator outlet C2, the third phase generator outlet C3, the fourth phase generator outlet C4, the fifth phase generator outlet C5, and the sixth phase generator outlet C6.

[0051] The two ends of the one-phase connecting tube 28, the two-phase connecting tube 29, the three-phase connecting tube 30, the four-phase connecting tube 31, the five-phase connecting tube 32, and the six-phase connecting tube 33 are respectively connected to the following interfaces in sequence: the one-phase liquid and gas flow channel A1 and the one-phase generator outlet C1, the two-phase liquid and gas flow channel A2 and the two-phase generator outlet C2, the three-phase liquid and gas flow channel A3 and the three-phase generator outlet C3, the four-phase liquid and gas flow channel A4 and the four-phase generator outlet C4, the five-phase liquid and gas flow channel A5 and the five-phase generator outlet C5, and the six-phase liquid and gas flow channel A6 and the six-phase generator outlet C6.

[0052] The positive and negative pressure conversion valve core 43 is composed of a conversion valve disc 53, a conversion valve core sleeve 54, a compression spring 56, and a spring seat 57. The conversion valve core sleeve 54 is a cylindrical structure with an open structure at one end and a smaller closed structure at the other end and a conical sealing surface on the inner side of the closed end. The spring seat 57 is a porous structure and is fixedly installed in the middle and lower part of the conversion valve core sleeve 54. The lower part of the conversion valve disc 53 is a three-claw or multi-claw guide structure, which forms an axial sliding fit with the inner wall of the conversion valve core sleeve 54. There is a conical sealing surface in the middle part, which is pressed tightly against the conical sealing surface on the conversion valve core sleeve 54 by the compression spring 56 between the conversion valve disc 53 and the spring seat 57 to form an axial sealing fit. A connecting rod extending a certain length from the upper part is fixedly fitted with the connecting rod extending from the push-pull actuator 44.

[0053] The positive and negative pressure conversion valve core 43 is installed in the middle hole inside the shell 42 and forms an axial sliding fit with the middle hole. It can move up and down under the action of the push-pull actuator 44. When a push-pull actuator 44 is in the retracted state, the corresponding one-phase generator outlet C1, two-phase generator outlet C2, three-phase generator outlet C3, four-phase generator outlet C4, five-phase generator outlet C5, six-phase generator outlet C6 is connected to the passage in a negative pressure state, and the high-speed airflow and drilling fluid are sucked into the liquid-gas separation chamber 22 from the screen surface. The liquid-gas separation After the separation, the drilling fluid overflows the water sealing weir plate 37 and is discharged outside the machine; when the push-pull actuator 44 is pushed out, the conversion valve core sleeve 54 first contacts the sealing gasket 48 to form an axial seal, and continued pushing will push the conversion valve disc 53 to slide downward relative to the conversion valve core sleeve 54, the seal between the two is released, the compression spring 56 is compressed, and the passage connected to the corresponding generator outlet will be connected to the positive pressure channel 46, becoming a positive pressure state, and the high-speed airflow is discharged from the channel to the outside, and flows through the screen in the opposite direction to make the drill cuttings on the screen surface jump off the screen surface, and at the same time, the mesh of the corresponding screen working area is cleaned and regenerated.

[0054] like Figure 13 As shown, the electronic control system mainly consists of the front-end vibration motor terminal M1, the rear-end vibration motor terminal M2, the screen surface inclination adjustment device motor terminal M3, the air pump motor terminal M4, the thermal relay FR3, the screen surface inclination adjustment device motor forward control contactor KM1, the screen surface inclination adjustment device motor reverse control contactor KM2, the air pump motor control contactor KM3, the vibration motor control inverter BPQ, the pulse airflow generation controller KZQ, the vibration motor control circuit breaker QF1, the screen surface inclination adjustment device motor control circuit breaker QF2, the air pump motor control circuit breaker QF3, the pulse airflow generation controller circuit breaker QF4, the one-phase terminal F1, the two-phase terminal F2, the three-phase terminal F3, the four-phase terminal F4, the five-phase terminal F5, and the six-phase terminal F6.

[0055] The vibration motor control inverter BPQ and the vibration motor control circuit breaker QF1 are used to control the start, stop and speed regulation of the two vibration motors. The front vibration motor terminal group M1 and the rear vibration motor terminal group M2 are connected to the corresponding terminals of the two vibration motors through control lines, and make the two vibration motors rotate synchronously in opposite directions.

[0056] The forward control contactor KM1 of the screen surface inclination adjustment device motor, the reverse control contactor KM2 of the screen surface inclination adjustment device motor, and the screen surface inclination adjustment device motor control circuit breaker QF2 are used to control the start and stop and forward and reverse rotation of the screen surface inclination adjustment device motor. The screen surface inclination adjustment device motor terminal M3 is connected to the corresponding terminal of the screen surface inclination adjustment device motor through a control line to realize the adjustment of the screen surface inclination.

[0057] The air pump motor control contactor KM3 and the air pump motor control circuit breaker QF3 are used to control the start and stop of the air pump motor. The pulse airflow generation controller KZQ has the functions of start and stop, and AC to DC conversion, and especially has the function of setting the power-on and power-off time of each output terminal. The one-phase terminal F1, the two-phase terminal F2, the three-phase terminal F3, the four-phase terminal F4, the five-phase terminal F5, and the six-phase terminal F6 are respectively connected to the six-phase push-pull actuators on the positive and negative pressure pulse airflow generator through control lines to control the pulling back and pushing out time of each push-pull actuator, forming a positive and negative pressure circulating pulse airflow with a certain period and time ratio.

[0058] Thermal relay FR3, vibration motor control inverter BPQ, and pulse airflow generation controller KZQ can all provide overcurrent protection for each circuit.

[0059] like Figure 14 As shown, through the combined action of the electronic control system, the actuators and the device's own mechanism, all screens installed on the device have six cyclically alternating working states, namely, one-phase screen working state Z1, two-phase screen working state Z2, three-phase screen working state Z3, four-phase screen working state Z4, five-phase screen working state Z5, and six-phase screen working state Z6; in all working states, each screen always has at least five negative pressure working areas Y and one positive pressure working area X, or is converted to a negative pressure working area Y within the time of the start of two adjacent states.

[0060] As time goes by, at the starting time 0 of the one-phase screen working state, the starting time t1 of the two-phase screen working state, the starting time t2 of the three-phase screen working state, the starting time t3 of the four-phase screen working state, the starting time t4 of the five-phase screen working state, and the starting time t5 of the six-phase screen working state, the positive pressure state working area X keeps moving forward until a pulse cycle period T ends and then restarts from the starting time 0 of the one-phase screen working state, thereby realizing that the high-speed airflow driven by negative pressure continuously carries the drilling fluid through the screen, the high-speed airflow driven by positive pressure continuously blows up the drill cuttings, and acts on all areas of the screen in a reciprocating cycle according to the pulse cycle period T, and cooperates with the forward throwing force generated by the vibration of the screen itself, so that the drill cuttings move forward continuously and are finally discharged outside the machine, and all the meshes on the screen are periodically cleaned and regenerated.

[0061] It should be pointed out that the vibrating screen working under the working principle of the present invention no longer needs to separate materials by obtaining a high excitation intensity through high frequency and large amplitude. The vibrating screen only needs to provide low frequency or high frequency small amplitude vibration to assist in transporting drill cuttings. It should be pointed out in particular that the present embodiment only describes a scheme with six phases and four screens, but is not limited to the present embodiment. It can also be a different combination of other phase numbers and screen numbers. The positive and negative pressure pulse airflow generator in the present embodiment is only to realize and explain the principle of material separation driven by positive and negative pressure circulating pulse airflow, and is not limited to any structure under this principle. The electronic control system described in the present embodiment is only to illustrate the control points required for the working principle of the present invention, namely, the frequency modulation control of the vibration motor, the forward and reverse control of the screen surface inclination adjustment device, the start and stop control of the air pump, and especially the positive and negative pressure state and period control of the positive and negative pressure circulating pulse airflow, and is not limited to the control method described in the present embodiment. A variety of different control schemes such as relay control, PLC control or single-chip microcomputer control can be adopted.

[0062] Combine Figures 1 to 14 In addition to the above content, the method of driving the vibrating screen with positive and negative pressure cycle pulse airflow is described:

[0063] 1. The drilling fluid to be processed first enters the feeding tank 6, and flows downward through the feeding port on the feeding tank 6 to the upper surface of the tail screen of the composite screen 2;

[0064] 2. The vibrating body composed of the vibrating box 16, the vibrating motor 18, the screen 19, and the screen bed 20 generates an exciting force under the excitation of the vibrating motor 18 to move the drilling fluid and the solid phase therein forward;

[0065] 3. The air intake of the opened air pump 4 is connected to the negative pressure channel 47 of the positive and negative pressure pulse airflow generator 5 through the negative pressure connecting pipe 35, and the air exhaust port is connected to the positive pressure channel 46 of the positive and negative pressure pulse airflow generator 5 through the positive pressure connecting pipe 34; the negative pressure channel 47 is always connected to five or six of the first phase generator outlet C1, the second phase generator outlet C2, the third phase generator outlet C3, the fourth phase generator outlet C4, the fifth phase generator outlet C5, and the sixth phase generator outlet C6. According to the phase sequence of C1 to C6, within a pulse cycle T, the push-pull actuators 44 corresponding to the six generator outlets push out the positive and negative pressure conversion valve core 43 one by one and maintain them for a certain time (the time of the six phases is not necessarily continuous). During this time, the generator outlet is connected to the positive pressure channel 46 and the exhaust port of the air pump 4 and becomes positive pressure, and the push-pull actuators 44 corresponding to the remaining channels are in a retracted state, that is, the corresponding passages are all in a negative pressure state; through the above process, all screens 19 are synchronously realized Figure 14In one pulse cycle T, the working state of the screen mesh changes from Z1 to Z6. In the negative pressure working area Y, a positive high-speed airflow is generated on the mesh surface, continuously carrying the drilling fluid on the screen surface through the screen. In the positive pressure working area X, a reverse high-speed airflow is generated on the mesh surface, blowing up the drill cuttings and sweeping the mesh holes to clean and regenerate them. Since the positive pressure working area X always moves forward in a cycle, the forward throwing force generated by the vibration of the vibrating screen is used to transport the drill cuttings forward out of the machine.

[0066] 4. The drilling fluid that has passed through the sieve enters the sieve bed 20 together with the high-speed airflow, and enters the liquid-gas separation chamber 22 through the liquid-gas outlet 40 at the bottom of the sieve bed 20. The drilling fluid settles at the bottom of the liquid-gas separation chamber 22, and finally flows over the water-sealed weir plate 37 and out of the machine. The gas flows upward in the fixed liquid-gas flow channel, passes through the connecting pipe, enters the negative pressure channel 47 of the positive-negative pressure pulse airflow generator 5, and is finally sucked into the air pump 4 through the negative pressure connecting pipe 35.

[0067] 5. In order to adapt to more working conditions, the negative pressure and airflow volume can be adjusted by adjusting the negative pressure regulating relief valve 50 on the positive and negative pressure pulse airflow generator 5;

[0068] 6. The airflow discharged from the air pump 4 is divided into two paths. One path passes through the positive pressure channel 46 of the positive and negative pressure pulse airflow generator 5, enters a path opened by the push-pull actuator 44, enters the liquid-gas flow channel corresponding to the liquid-gas separation chamber 22 through the connecting pipe, and finally enters the channel corresponding to the sieve bed 20 to form a reverse high-speed airflow that passes through the sieve outward; the other path passes through the positive pressure regulating pressure relief valve 51 with a set pressure and is discharged outside the machine. The pressure of this pressure relief valve can be adjusted arbitrarily.

[0069] 7. If the equipment needs to be used as a conventional vibrating screen, turn off the air pump 4 and adjust the vibration motor control inverter BPQ to a high frequency. Since the principle of material separation driven by positive and negative pressure pulse airflow can effectively extend the service life of the screen, the frequency can be higher than that of a conventional vibrating screen to enhance the processing effect, and the overall service life of the screen is still higher than that of a conventional vibrating screen.

[0070] 8. When it is necessary to adjust the screen surface inclination angle to change the flow rate of the drilling fluid on the screen surface, turn on the forward and reverse control of the screen surface inclination angle adjustment device 8. When rotating forward, the composite screen 2 rotates counterclockwise around the composite screen mounting pin 12, the screen surface inclination angle increases, and the liquid flow rate slows down; when rotating reversely, the composite screen 2 rotates clockwise around the composite screen mounting pin 12, the screen surface inclination angle decreases, and the liquid flow rate speeds up.

[0071] This invention proposes a new screening method and principle: positive and negative pressure pulse airflow driven separation method. Its characteristics are:

[0072] 1. It no longer relies on the high-frequency and large-amplitude vibration generated by the vibrating screen itself to screen and obtain the materials on and under the screen. Instead, it uses high-speed pulse airflow with alternating positive and negative pressure cycles to drive material separation. Relying solely on high-frequency vibration to separate materials will greatly reduce the screening efficiency and processing capacity when dealing with high-viscosity media, and it is easy to cause screen sticking and pulp running. When installing a high-mesh screen with fine mesh, the processing capacity will also be greatly reduced and the life of the screen will be shortened. When dealing with high-moisture content media, the dehydration efficiency is low and the moisture content of the materials on the screen is high. The vibrating screen driven by positive and negative pressure pulse airflow still has a large processing capacity when installed with a high-mesh screen, is not easy to cause screen sticking and pulp running, has a long screen life, and has high dehydration efficiency.

[0073] Second, the negative pressure pulse airflow in the positive and negative pressure circulating pulse airflow flows from the top of the screen to the bottom of the screen. The gas and liquid materials on the screen and the materials smaller than the mesh size are carried by the high-speed airflow and quickly pass through the screen below the screen; the positive pressure pulse airflow flows from the bottom of the screen to the top of the screen, and the materials on the screen that cannot pass through the screen are quickly blown up, thereby achieving material separation;

[0074] 3. The positive and negative pressure cyclic pulse airflow acts on the mesh surface, dividing the mesh surface into several working areas corresponding to the same number of air flow channels. Each working area works alternately with positive pressure airflow and negative pressure airflow;

[0075] Fourth, the several working areas of the mesh surface are divided into two states according to the positive and negative pressure airflows, namely the positive pressure state and the negative pressure state. The two states change periodically, and the number and duration of the positive pressure state and the negative pressure state are operated in a certain ratio;

[0076] 5. The conveying of the material on the screen is completed by the lifting effect of the positive pressure airflow and the forward throwing force generated by the vibration. Unlike relying solely on high-frequency vibration, it can effectively reduce the wear of the screen by the material on the screen.

[0077] The mechanism of positive and negative pressure cyclic pulse airflow in the present invention is: first, there must be a dual-purpose air source for suction and exhaust, and the air intake and exhaust ports of the air source can be divided into multiple paths through a distribution mechanism; each path forms a passage with an independent working area on the screen through a connecting mechanism; each path is provided with a control mechanism to control the selection of the air intake or exhaust port connected to the air source, that is, negative pressure or positive pressure, and the control mechanism can also control the duration and time interval of the negative pressure and positive pressure; each path is provided with a liquid-gas separation mechanism so that the liquid phase can be discharged smoothly; the air intake and exhaust ports of the air source are provided with pressure regulating and gas release devices, which can set the system pressure to ensure stable operation of the system; the implementation of the above mechanism can be the scheme in the embodiment but is not limited to this.

[0078] The remarkable effects of the present invention are:

[0079] 1. The positive high-speed airflow carries the drilling fluid through the screen surface quickly, which can greatly increase the processing capacity, improve the recovery rate of drilling fluid, reduce the moisture content of drill cuttings, and reduce the discharge of drilling waste;

[0080] 2. The reverse high-speed airflow allows the drill cuttings to quickly separate from the screen surface, effectively solving the problem of screen sticking, reducing the contact time between the drill cuttings and the screen, continuously cleaning the mesh to recycle it, reducing the probability of critical-sized drill cuttings passing through the screen, and reducing secondary crushing of the drill cuttings and wear of the screen;

[0081] 3. Positive and negative high-speed airflows act on all screen working areas according to a certain cycle and time ratio and circulate alternately. While maintaining efficient and stable working conditions, parameters such as cycle, time ratio, air pressure, and air flow can be quickly adjusted through the electronic control system to meet wide adaptability under various working conditions and facilitate the further development of equipment automation, intelligent control, and remote network monitoring.

[0082] 4. The positive airflow lifting and vibration combined conveying of drill cuttings has low requirements on vibration intensity. Only low-frequency vibration or high-frequency small-amplitude vibration is required, which can effectively extend the service life of the equipment and screen.

[0083] 5. Without increasing the number and area of ​​the screens, the present invention is adapted to high-mesh screens with high separation accuracy, which can meet the requirements of high separation accuracy and large processing capacity at the same time. The service life of the high-mesh screens that are easily damaged is also guaranteed. Therefore, it can replace multiple conventional vibrating screens, high-energy consumption desanders and desilters, reduce the frequency and duration of centrifuge startup, simplify the solids control system process, and greatly reduce energy consumption. The drilling fluid with low solid content can effectively improve drilling efficiency and reduce downhole accidents. It is not easy to form precipitation in storage tanks and pipelines, which minimizes the discharge of waste drilling fluid and reduces the consumption of drilling fluid materials and the workload of solids control system maintenance.

[0084] A comparative experiment was conducted on drilling fluid screening under negative pressure. The experimental results show that:

[0085] 1. The processing capacity of the vibrating screen with the same mesh size is greatly increased under negative pressure compared with that under normal pressure, especially when high mesh size screen is installed and high viscosity drilling fluid is processed. However, the processing capacity will decrease after a period of time. The reason for this is that the mesh of the screen is gradually blocked when it is under negative pressure for a long time.

[0086] 2. During the negative pressure experiment, positive pressure experiments were interspersed with the same experimental device, and a comparative experiment was conducted, that is, an alternating positive and negative pressure experiment. When the screen mesh was working under negative pressure for a certain period of time, the positive pressure state was promptly turned on, which effectively prevented the mesh from being clogged. The higher the frequency of the positive pressure state being turned on, the more significant the effect. In addition, under positive pressure, the drill cuttings on the screen surface were lifted by the airflow, and the speed of outward transportation was accelerated. The screening efficiency of the screen mesh remained unchanged after long-term operation, and the mesh surface did not wear out. However, the screen mesh that had been working under normal pressure or negative pressure showed a gradual decrease in processing capacity and partial damage to the screen mesh.

[0087] 3. Based on the positive and negative pressure alternating experiment, the mesh surface of the screen was divided into several independent areas, and pulsed airflow with alternating positive and negative pressure was loaded in each area, so that one area was always in a positive pressure state and the other areas were in a negative pressure state. This was used to conduct a comparative experiment on the processing capacity. The experimental results showed that the working state loaded with pulsed airflow with alternating positive and negative pressure had a significant increase in processing capacity compared with the normal pressure working state, was more stable than the negative pressure working state, and did not show any processing capacity attenuation. At the same time, it showed the beneficial effects of fast and smooth drilling cuttings transportation and extended screen service life. After reducing the vibration intensity and amplitude, the working state loaded with pulsed airflow with alternating positive and negative pressure was not affected, but both the normal pressure working state and the negative pressure working state showed slow drilling cuttings transportation and decreased processing capacity.

Claims

1. A positive and negative pressure cycle pulse vibrating screen, comprising a frame, a vibrating screen installed in the frame, the vibrating screen comprising a vibrating motor, a screen bed, and a screen mesh, a feeding mechanism corresponding to the vibrating screen being provided on the upper side, and a liquid-gas separation mechanism being connected to the lower side for smooth discharge of liquid, characterized in that: It also includes a dual-purpose air source for suction and exhaust installed on the frame, the exhaust port and the intake port of the air source are respectively connected to the positive and negative pressure interfaces of the positive and negative pressure pulse airflow control mechanism, the positive and negative pressure pulse airflow control mechanism forms an airflow passage with the screen surface of the screen through a connecting mechanism and controls the duration and time interval of the positive and negative pressures, the negative pressure pulse airflow flows from the upper screen to the lower screen, and the positive pressure pulse airflow flows from the lower screen to the upper screen; the intake port and the exhaust port of the air source are both provided with pressure regulating and gas releasing devices, the vibration motor is connected to the frequency conversion device, and also includes an electric control system located on one side of the frame, the control lines of which are respectively connected to the corresponding electrical equipment and used to adjust the parameters of the electrical equipment; The airflow passages are multiple, each corresponding to an independent working area on the screen; each corresponding airflow passage in the positive and negative pressure pulse airflow control mechanism is provided with a positive and negative pressure conversion mechanism. In one pulse cycle, one or more airflow passages are positive pressure airflow for a certain period of time according to the order of the airflow passage positions, and the remaining airflow passages are negative pressure airflow passages. The positive and negative pressure airflows in the independent working areas of the screen cycle in a cycle, and the duration of the positive and negative pressures is adjustable and operates proportionally. The sieve is sealably fixed on the sieve bed. The sieve bed divides the sieve into multiple independent working areas, each of which is connected to a liquid-gas separation mechanism. From top to bottom, an independently sealed liquid-gas flow channel is formed by the sieve bed area corresponding to each independent working area of ​​the sieve and the internal area of ​​the liquid-gas separation mechanism. The air flow path is correspondingly connected to the liquid-gas flow channel.

2. A positive and negative pressure cycle pulse vibrating screen according to claim 1, characterized in that: The vibrating screen is a composite screen, which consists of three parts: a parametric body, a suspended vibration isolator, and a non-parametric body. The parametric body consists of a vibration box, a vibration motor, a screen, and a screen bed; the non-parametric body consists of a rear support of the vibration isolator, a liquid-gas separation mechanism, and a front support of the vibration isolator. The liquid-gas separation mechanism is located below the screen bed, and the rear support and the front support of the vibration isolator are fixedly installed at the four corners outside the liquid-gas separation mechanism; the parametric body and the non-parametric body are connected via a suspended vibration isolator. The parametric body provides vibration function, and the non-parametric body provides liquid The sieve bed has the functions of gas separation and external air flow channel; the sieve bed is a structure in which a sieve bed frame is covered with a non-metallic elastic material. The sieve bed frame is a metal welded structure, and a rectangular circumference is formed by angle steel. A plurality of flat steels are evenly distributed in the width direction of the rectangular circumference to form n channels corresponding to the number and position of the air flow channels. A plurality of small flat steels are evenly distributed in the length direction as reinforcement ribs. Each channel has a liquid-gas outlet at the bottom of the sieve bed connected to an independent area in the liquid-gas separation mechanism. The sieve bed divides the screen into n areas of corresponding position and size.

3. A positive and negative pressure cycle pulse vibrating screen according to claim 2, characterized in that: The liquid-gas separation mechanism is a liquid-gas separation chamber, which is mainly composed of a separation chamber box, a separation chamber partition, and a separation chamber sieve bed connecting sleeve. The separation chamber box is a box structure with an opening on one side. The interior is divided into corresponding n independent area chambers by the separation chamber partition, and the lower edge of the separation chamber partition is at a certain distance from the bottom of the box, so that the lower parts of the n independent area chambers are all connected to the side opening of the box. The side opening is rectangular, and a water-sealed weir plate is installed in the lower half of the rectangular opening. The upper edge of the water-sealed weir plate is higher than the lower edge of the separation chamber partition. When the box is filled with drilling fluid, the drilling fluid submerges the separation chamber partition to form n sealed compartments, and at the same time, the drilling fluid overflows the water-sealed weir plate and is discharged out of the machine. Above each sealed compartment is a separation chamber sieve bed connecting sleeve with the same number of sieve beds. The separation chamber sieve bed connecting sleeve is sealed and connected to the liquid and gas outlet of the corresponding sieve bed channel to form an independent liquid-gas flow channel.

4. The positive and negative pressure cycle pulse vibrating screen according to claim 3, characterized in that: The air source is an air pump with an air intake and an air exhaust port, and the positive and negative pressure pulse airflow control mechanism is a positive and negative pressure pulse airflow generator, which is composed of a shell, a positive and negative pressure conversion valve core, a push-pull actuator, a right end cover, a sealing gasket, a generator output connector, a negative pressure regulating pressure relief valve, a positive pressure regulating pressure relief valve, and a left end cover; there are two through-hole channels, a positive pressure channel and a negative pressure channel, in the shell, and each channel has an external interface, which is a positive pressure interface and a negative pressure interface, connecting the exhaust port and the air intake port of the air source; the left end face of the shell is sealed with a left end cover, and a negative pressure regulating pressure relief valve and a positive pressure regulating pressure relief valve are sealed on the left end cover, corresponding to the negative pressure channel and the positive pressure channel respectively; the right end of the shell The right end cover is installed with a face seal; n through holes are evenly distributed on one side of the shell, and n through holes are also evenly distributed on the other side and on the inner wall between the two holes of the positive pressure channel and the negative pressure channel, forming n groups of three-hole coaxial structures, and n push-pull actuators are evenly installed on the plane on one side of the upper hole of the shell, and the push-pull actuators perform the two actions of pushing out and pulling back according to the electric control signal; n generator output connectors are evenly installed on the plane on one side of the lower hole of the shell, and the sealing gasket is pressed and fixed in the lower hole by the generator output connector; n generator output connectors are correspondingly connected to n liquid-gas flow channels; the positive and negative pressure conversion valve core is composed of a conversion valve disc, a conversion valve core sleeve, a compression spring, and a spring seat. The conversion valve core sleeve is a cylindrical structure with an open end. The spool has a plurality of springs, each of which is provided with a plurality of springs, and a plurality of springs are provided with a plurality of springs. The spool has a plurality of springs, each of which is provided with a plurality of springs. The spool has a plurality of springs, each of which is provided with a plurality of springs. The spool has a plurality of springs, each of which is provided with a plurality of springs. The spool has a plurality of springs, each of which is provided with a plurality of springs. The spool has a plurality of springs, each of which is provided with a plurality of springs. When in the pulled-back state, the passage connected to the corresponding generator outlet is in a negative pressure state, and the high-speed airflow and drilling fluid are sucked into the liquid-gas separation chamber from the screen surface. After liquid-gas separation, the drilling fluid overflows the water sealing weir plate and is discharged out of the machine. When the push-pull actuator is pushed out, the conversion valve core sleeve first contacts the sealing gasket to form an axial seal. Continuing to push the conversion valve disc will push downward relative to the conversion valve core sleeve. The seal between the two is released, the compression spring is compressed, and the passage connected to the corresponding generator outlet will be connected to the positive pressure channel and become a positive pressure state. The high-speed airflow is discharged from the channel to the outside, and flows through the screen in the opposite direction to make the drill cuttings on the screen surface jump off the screen surface. At the same time, the mesh of the corresponding screen working area is cleaned and regenerated.

5. A working method of a positive and negative pressure cycle pulse vibrating screen, characterized in that: Applied to the positive and negative pressure cycle pulse vibrating screen according to claim 4, the working method includes: (1) The drilling fluid to be treated first enters the feed tank and flows downward through the feed port on the feed tank to the upper surface of the tail screen of the composite screen; (2) The vibrating body generates an exciting force under the excitation of the vibration motor, which causes the drilling fluid and the solid phase therein to move forward; (3) Turn on the air pump, connect the air pump suction port to the negative pressure channel of the positive and negative pressure pulse airflow generator, and connect the air pump exhaust port to the positive pressure channel of the positive and negative pressure pulse airflow generator; the positive and negative pressure pulse airflow generator and the screen form n airflow channels, and a positive high-speed airflow is generated on the mesh surface corresponding to the negative pressure airflow to continuously carry the drilling fluid on the screen surface through the screen, and a reverse high-speed airflow is generated on the mesh surface corresponding to the positive pressure airflow, blowing up the drill cuttings and sweeping the mesh holes to clean and regenerate them. In one pulse cycle, one or more airflow channels are positive pressure airflows for a certain period of time, and circulate in sequence according to the position of the airflow channels, so that the mesh area corresponding to the positive pressure airflow moves forward in a cycle, and the drill cuttings are transported forward out of the machine in conjunction with the forward throwing force generated by the vibration of the vibrating screen; (4) By setting the parameters of the electronic control system, the switching action of each airflow path in the positive and negative pressure pulse airflow generator is controlled, and each independent working area of ​​the screen is divided into two working states according to the positive and negative pressure airflows, which are periodically changed, and the quantity and duration are operated in a certain proportion. The positive and negative pressure airflow duration, the positive and negative pressure airflow time interval, and the pulse cycle parameters of each airflow channel are adjusted to achieve the regulation of processing capacity, drill cuttings conveying speed, and drill cuttings moisture content; (5) The drilling fluid that has passed through the screen enters the screen bed together with the high-speed airflow, and enters the liquid-gas separation chamber through the liquid-gas outlet at the bottom of the screen bed. The drilling fluid settles at the bottom of the liquid-gas separation chamber, and finally flows over the water-sealed weir plate and out of the machine. The gas flows upward in the fixed liquid-gas flow channel, enters the negative pressure channel of the positive and negative pressure pulse airflow generator through the connecting pipe, and is finally sucked into the air pump through the negative pressure connecting pipe; (6) In order to adapt to more working conditions, the negative pressure and airflow volume can be adjusted by adjusting the negative pressure regulating relief valve on the positive and negative pressure pulse airflow generator; (7) The airflow discharged from the air pump is divided into two paths. One path passes through the positive pressure channel of the positive and negative pressure pulse airflow generator, enters a path opened by the push-pull actuator, enters the liquid-gas flow channel corresponding to the liquid-gas separation chamber through the connecting pipe, and finally enters the channel corresponding to the sieve bed to form a reverse high-speed airflow that passes through the sieve outward; the other path passes through the positive pressure regulating pressure relief valve with a set pressure and is discharged outside the machine; (8) If the equipment needs to be used as a conventional vibrating screen, turn off the air pump and adjust the vibration motor control inverter to high frequency.

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