Oily wastewater treatment system and control method thereof

Abstract

The invention discloses an oil-containing wastewater treatment system and a control method thereof. The oil-containing wastewater treatment system comprises: a wastewater tank, which is used to store the oil-containing wastewater to be treated, wherein a liquid level meter is arranged therein, which is used to monitor the liquid level of the wastewater tank in real time; a liquid inlet pump, which is used to pump the oil-containing wastewater in the wastewater tank, wherein the inlet of the pump is connected to the outlet of the wastewater tank; a pretreatment device, which is used to pre-separate solids and colloidal suspended matter in the wastewater, wherein the liquid inlet is connected to the outlet of the liquid inlet pump, and comprises two sets of pretreatment equipment connected in parallel with each other, wherein the two sets of pretreatment equipment can be switched to operate independently, and each set of pretreatment equipment is provided with a differential pressure meter; a water-oil separation device, which is used to separate water and oil in the wastewater, wherein the water phase outlet and the oil phase outlet are arranged therein, wherein the liquid inlet is connected to the liquid outlet of the pretreatment device, wherein the water-oil separation device is provided with a differential pressure meter, and wherein the water phase outlet is provided with a flow meter. The oily wastewater treatment system provided by the present invention is provided with a pretreatment device and a recovery device, which can effectively separate wastewater containing oil pollution and reduce the content of oil pollution in the wastewater, and can be applicable to various oil products, gas processing and any actual liquid / liquid coagulation separation process in the chemical industry; a pretreatment device is provided to pre-separate solids and colloid-bound suspended matter in the wastewater, which can effectively extend the service life of the water-oil separation device; two sets of pretreatment equipment are provided, one for use and the other for backup, so as to reduce the frequency of shutdown maintenance.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and in particular, relates to an oily wastewater treatment system and a control method thereof. Background Art

[0002] In today's rapidly developing industrial era, the leapfrog progress of my country's industrial technology has undoubtedly injected strong impetus into economic growth, but it is also accompanied by a series of environmental challenges, among which the discharge of industrial oily wastewater is particularly severe. These wastewaters, rich in oil, suspended solids and a variety of harmful chemicals, are directly discharged into natural water bodies such as rivers, lakes and even oceans without effective treatment, posing an unprecedented threat to aquatic ecosystems.

[0003] Once oily wastewater enters a water body, its hazards are multifaceted and far-reaching. The oil layer quickly covers the water surface, forming an impenetrable barrier, which seriously hinders the oxygen exchange between the air and the water, causing a sharp drop in the dissolved oxygen content of the water. This change directly threatens the survival basis of aquatic organisms, restricts algae photosynthesis, and thus affects the normal operation of the entire food chain, destroying the ecological balance. What is more serious is that oil and the harmful chemicals it brings will penetrate into the organisms, giving aquatic plants and animals an unnatural oily smell or toxicity, which not only affects people's food safety, but may also accumulate and amplify through the food chain, posing a potential risk to human health. In addition, long-term oil pollution can easily lead to eutrophication of water bodies, deterioration of water quality, and even cause water bodies to stink, greatly reducing the availability of water resources and having an adverse impact on the quality of life and economic development of surrounding residents.

[0004] Faced with this grim situation, the effective treatment of oily wastewater has become a key issue that needs to be urgently addressed in the field of environmental protection. Traditionally, single or combined technologies such as physical methods (such as gravity separation and flotation), chemical methods (such as coagulation and sedimentation) and biological methods (such as biodegradation) are often used to treat oily wastewater. Although these technologies have achieved the separation of oil and water to a certain extent, they often have limitations such as low treatment efficiency, high energy consumption, easy to produce secondary pollution or difficulty in coping with complex water quality changes. Especially in the fields of petroleum, gas and chemical industries, the separation of high-concentration emulsions has become a technical bottleneck. It is not only difficult to handle, but also costly, and it is difficult to meet increasingly stringent environmental protection requirements. In addition, most existing systems rely on manual operation and have a low degree of automation, making it difficult to achieve precise control and optimization of the wastewater treatment process.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide an oily wastewater treatment system and a control method thereof to achieve efficient, environmentally friendly and economical treatment of oily wastewater.

[0007] To achieve the above object, the technical solution of the present invention is:

[0008] In a first aspect, the present invention provides an oily wastewater treatment system, comprising:

[0009] A wastewater tank is used to store oily wastewater to be treated, and a liquid level meter is provided therein to monitor the liquid level of the wastewater tank in real time;

[0010] A liquid inlet pump, used for pumping the oily wastewater in the wastewater tank, wherein the inlet of the pump is connected to the outlet of the wastewater tank;

[0011] The pretreatment device is used to pre-separate solids and colloidal suspended matter in the wastewater. Its liquid inlet is connected to the outlet of the liquid inlet pump, and includes two sets of pretreatment equipment connected in parallel. The two sets of pretreatment equipment can be switched to operate independently, and each set of pretreatment equipment is equipped with a differential pressure gauge;

[0012] The water-oil separation device is used to separate water and oil in wastewater, and is provided with a water phase outlet and an oil phase outlet. Its liquid inlet is connected to the liquid outlet of the pretreatment device. The water-oil separation device is provided with a differential pressure gauge, and its water phase outlet is provided with a flow meter.

[0013] Furthermore, the oily wastewater treatment system also includes a recovery device, the waste outlets of the pretreatment device and the water-oil separation device are respectively connected to the liquid inlet of the recovery device, the liquid outlet of the recovery device is connected to the inlet of the wastewater tank, and a filter component is provided between the liquid inlet and the liquid outlet of the recovery device.

[0014] Furthermore, the water-oil separation device includes a shell, the water phase outlet and the oil phase outlet are arranged on the shell, located downstream of the separation membrane group, the water phase outlet is arranged at the lower part of the shell, and the oil phase outlet is arranged at the upper part of the shell, and a separation membrane group is arranged inside the shell.

[0015] Furthermore, an oil collecting pipe is vertically arranged on the upper part of the shell, an oil phase outlet is arranged on the top of the oil collecting pipe, and an interface meter is arranged on the side of the oil collecting pipe for monitoring the position of the oil-water interface in the oil collecting pipe.

[0016] Furthermore, a fluid distributor is provided between the liquid inlet of the water-oil separation device and the separation membrane group.

[0017] Furthermore, the oily wastewater treatment system also includes a backwash device, including a compressed air module and a backwash water module. Each set of pretreatment equipment is provided with a backwash port, and the backwash device is respectively connected to the backwash port of each set of pretreatment equipment.

[0018] Furthermore, the oily wastewater treatment system also includes a control system for automatically controlling the operating state of the oily wastewater treatment system.

[0019] In a second aspect, the present invention provides a control method for an oily wastewater treatment system, the method comprising:

[0020] Automatically control the start and stop of the water-oil separation process according to the amount of wastewater in the wastewater tank;

[0021] In the running state, when the wastewater level is less than or equal to the first level, the water-oil separation process automatically stops;

[0022] In the shutdown state, when the wastewater level is greater than or equal to the second level, the water-oil separation program starts automatically.

[0023] Further, the operating state of the pretreatment device is automatically switched according to the flux of the pretreatment device;

[0024] Determine the flux of the pretreatment device based on the inlet and outlet pressure difference of the pretreatment device;

[0025] When the inlet and outlet pressure difference of the pretreatment equipment is greater than or equal to the preset value, the currently running pretreatment device automatically switches to the backwash mode, and the other pretreatment device starts to participate in the operation of the water-oil separation program.

[0026] Furthermore, the operating power of the liquid inlet pump is adjusted according to the liquid inlet pressure and / or the water phase outlet flow rate of the water-oil separation device.

[0027] After adopting the above technical solution, the oily wastewater treatment system and control method thereof provided by the present invention have the following beneficial effects.

[0028] (1) The oily wastewater treatment system provided by the present invention is equipped with a pretreatment device and a recovery device, which can effectively separate wastewater containing oil pollution and reduce the content of oil pollution in the wastewater. It can be applied to various oil products, gas processing and any practical liquid / liquid condensation separation process in the chemical industry.

[0029] (2) The oily wastewater treatment system provided by the present invention is equipped with a pretreatment device to pre-separate the solids and suspended solids in the wastewater, which can effectively extend the service life of the water-oil separation device; two sets of pretreatment equipment are provided, one for use and one for backup, to reduce the frequency of shutdown maintenance.

[0030] (3) The oily wastewater treatment system provided by the present invention is equipped with a pretreatment device and a recovery device, which can effectively collect and filter the wastewater and waste in the treatment process and recycle them into the wastewater tank, thereby reducing the waste of water resources, realizing the maximum utilization of resources, and complying with the concept of green environmental protection.

[0031] (4) The oily wastewater treatment system provided by the present invention is equipped with a pretreatment device and a backwashing device, which can perform self-cleaning without affecting the overall operation of the system, effectively extending the service life of the equipment and reducing maintenance costs. At the same time, the modular design makes troubleshooting and replacement easier and faster, reducing downtime.

[0032] (5) The present invention uses a variety of sensors such as liquid level gauges, differential pressure gauges, interface meters, flow meters, etc. to accurately monitor various key parameters in the wastewater treatment process, providing a reliable basis for system control. It can automatically control the start and stop of the water-oil separation program, automatically switch the pretreatment equipment and perform backwashing, and automatically adjust the operating power of the liquid inlet pump. No manual operation is required, and the system runs fully automatically, reducing operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings are part of the present invention and are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but do not constitute an improper limitation of the present invention. Obviously, the drawings described below are only some embodiments. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the accompanying drawings:

[0034] Figure 1 It is a system schematic diagram of the oily wastewater treatment system of the present invention.

[0035] In the figure:

[0036] 10. Wastewater tank; 11. Liquid level meter;

[0037] 20. Liquid inlet pump;

[0038] 30. Pretreatment device; 31. Pretreatment equipment; 311. Filter element;

[0039] 40. Water-oil separation device; 41. Shell; 411. Oil collecting pipe; 412. Interface meter; 42. Separation membrane group; 43. Fluid distributor;

[0040] 50. Recovery device; 51. Bag filter;

[0041] 60. Backwash device; 61. Compressed air module; 62. Backwash water module;

[0042] 70. Flow meter;

[0043] 80. Pressure transmitter;

[0044] 90. Differential pressure gauge.

[0045] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but are intended to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0046] 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 used to limit the scope of the present invention.

[0047] In the description of the present invention, it should be noted that the directions or positional relationships indicated by terms such as “upper”, “lower”, “front”, “back”, “left”, “right”, “vertical”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0048] 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, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0049] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0050] [Example 1]

[0051] The present embodiment provides an oily wastewater treatment system, which mainly includes a wastewater tank 10 , a liquid inlet pump 20 , a pretreatment device 30 and a water-oil separation device 40 .

[0052] The wastewater tank 10 is used to store the oily wastewater to be treated, and is provided with a liquid level meter 11, preferably a field remote liquid level meter 11, for real-time monitoring of the liquid level of the wastewater tank 10. A control valve is provided at the outlet of the wastewater tank 10 to control the flow of the oily wastewater by opening and closing the control valve.

[0053] The inlet pump 20 is used to pump the oily wastewater in the wastewater tank 10. Its inlet is connected to the outlet of the wastewater tank 10. Its operating power is adjustable according to the pressure of the water-oil separation device 40 and the water flow rate.

[0054] The pretreatment device 30 is used to pre-separate solids and colloidal suspended matter in wastewater, which can effectively extend the service life of the water-oil separator 40. Its liquid inlet is connected to the outlet of the liquid inlet pump 20, and its liquid outlet is connected to the liquid inlet of the water-oil separator 40.

[0055] Further, the pretreatment device 30 includes two sets of pretreatment equipment 31 connected in parallel, and the two sets of pretreatment equipment 31 can be switched to operate independently. Each set of pretreatment equipment 31 is provided with a differential pressure gauge 90, and the liquid inlet and the liquid outlet are provided with automatic valves for automatic switching. In a preferred embodiment, the oily wastewater treatment system also includes a backwashing device 60, including a compressed air module 61 and a backwashing water module 62, each set of pretreatment equipment 31 is provided with a backwashing port, and the backwashing device 60 is respectively connected to the backwashing port of each set of pretreatment equipment 31.

[0056] Specifically, the pretreatment device 31 is provided with a liquid inlet, a liquid outlet and a backwashing port, an exhaust port is provided at the top, and a sewage outlet is provided at the bottom. A filter element 311 is provided in the pretreatment device 30, and the filtering direction is from inside to outside and from bottom to top. The liquid inlet is arranged at the lower part of the pretreatment device 31, and the liquid outlet is arranged at the upper part of the pretreatment device 31. Preferably, the filter element 311 is made of sintered metal fiber, and can be backwashed, backwashed, and replaced separately, saving costs.

[0057] When the inlet and outlet pressure difference of the pretreatment device 30 reaches the preset value, it means that the blockage degree of the filter element 311 of the currently operating pretreatment device 31 has reached the preset situation. At this time, the currently operating pretreatment device 31 sends a pressure difference alarm to remind the operator to switch the pretreatment device 31 and backwash the current pretreatment device 31. At this time, the operator opens the inlet and outlet valves of another set of spare pretreatment equipment 31, and closes the inlet and outlet valves of the pressure difference alarm device at the same time, switches the pretreatment device 31 and backwashes the alarmed device. In the backwashing procedure, the compressed air module 61 and the backwash port and sewage outlet of the pretreatment device 31 to be cleaned are opened, and the residual liquid in the pretreatment device 31 is discharged from the bottom sewage outlet. After the liquid is drained, the compressed air continues to backwash the filter element 311 from the inside to the outside, the impurities are blown off, and the filter element 311 recovers the flux, and then the backwash water module 62 is opened to clean the filter element 311, so that the filter element flux is completely restored, and then the valve is reset to wait for the next feeding. In a preferred embodiment, the backwash water module 62 is provided with a heating component, which can be turned on to allow hot water to flow into the filter element 311 for cleaning, thereby more effectively removing oil stains and improving the cleaning effect.

[0058] In a preferred embodiment, a pressure transmitter 80 and an explosion relief valve are provided behind the compressed air module 61, and automatic valves are provided at the liquid inlet, liquid outlet, sewage outlet and backwash outlet of the pre-separation module for automatic switching. When the pressure is too high, the automatic valve at the rear cannot be opened, and the pressure will be released when it exceeds the set pressure of the explosion relief valve.

[0059] The water-oil separation device 40 is used to separate water and oil in wastewater, and is provided with a water phase outlet, an oil phase outlet, a sewage outlet, and an exhaust outlet, and its liquid inlet is connected to the liquid outlet of the pretreatment device 30. The water-oil separation device 40 includes a housing 41, a separation membrane group 42 is provided inside the housing 41, a water phase outlet and an oil phase outlet are arranged on the housing 41, and are located downstream of the separation membrane group 42, the water phase outlet is arranged at the lower part of the housing 41, and the oil phase outlet is arranged at the upper part of the housing 41. Further, an oil collecting pipe 411 is vertically upwardly provided at the upper part of the housing 41, an oil phase outlet is provided at the top of the oil collecting pipe 411, and an interface meter 412 is provided on the side of the oil collecting pipe 411 for monitoring the position of the oil-water interface in the oil collecting pipe 411. A differential pressure gauge 90 is provided in the water-oil separation device 40, and a flow meter 70 is provided at its water phase outlet.

[0060] In a preferred embodiment, a fluid distributor 43 is provided between the liquid inlet of the water-oil separation device 40 and the separation membrane group 42. Exemplarily, a fluid reverse distributor can be used to make the wastewater entering the separation membrane group 42 first flow in the opposite direction of the separation membrane group, and the fluid pressure flowing out of the pipe port is released by impacting the head. After the fluid is turned back through the head, the flow rate is greatly reduced, and the liquid flow is gradually transformed from turbulent flow to laminar flow, and the fluid slowly and evenly enters the separation membrane group. Setting the fluid distributor 43 can change the fluid movement mode and reduce the flow rate, which can greatly improve the oil-water separation effect.

[0061] Specifically, the separation membrane group 42 is composed of a filtration layer, a demulsification layer, a coagulation layer, and a separation layer. After the wastewater flows into the separation membrane group 42, it first passes through the filtration layer from the inside to the outside. The filtration layer is made of metal glass fiber composite folding, has a large filtration area and high precision, effectively intercepts solid particles and improves the oil-water separation effect, and forms a double-layer interception with the pretreatment equipment 31, effectively extending the service life of the separation membrane group; the filtered oily wastewater enters the demulsification layer and the coagulation layer, and ultrafine fibers of different wire diameters are combined according to the set conditions. Through the principles of interception, collision, and inertial adsorption, the water-in-oil liquid form can be broken up, and large and small oil droplets aggregate and flow with the flow of liquid. Under the polarity of the separation layer, the oil droplets quickly leave the separation membrane group, and then move upward by density difference. After passing through a separation area of ​​a specific size, the oil droplets gradually gather on the upper layer of the equipment and enter the oil collecting pipe 411 on the upper part of the water-oil separation device 40. The position of the oil-water interface is observed through the interface meter 412, and the size of the oil phase outlet regulating valve is adjusted in real time. Due to the principle of density difference, the water phase gathers at the bottom of the equipment and flows out from the water phase outlet. The water phase outlet is provided with a regulating valve and a flow meter 70, and the valve opening can be adjusted by the water flow rate to make the liquid flow out stably. The water-oil separation device 40 is provided with a differential pressure gauge 90, which can monitor the inlet pressure and pressure difference in real time. When the pressure difference reaches the set value, the staff is reminded to replace the separation membrane group 42 in time.

[0062] In a preferred embodiment, the oily wastewater treatment system further includes a recovery device 50, which effectively collects and filters the wastewater and waste in the treatment process, and recycles them into the wastewater tank 10. Specifically, the waste outlets of the pretreatment device 30 and the water-oil separation device 40 are respectively connected to the liquid inlet of the recovery device 50, and the liquid outlet of the recovery device 50 is connected to the entrance of the wastewater tank 10. A filter component is provided between the liquid inlet and the liquid outlet of the recovery device 50 to intercept the residue in the wastewater and waste. Exemplarily, the filter component can adopt a bag filter 51, and the bag filter 51 adopts a 1-micron filter bag. After intercepting the solid impurities, the liquid flows back to the wastewater tank 10. The bag filter 51 is provided with a pressure differential transmitter, and the filter bag is replaced in time when the pressure differential reaches the set value.

[0063] In a preferred embodiment, the outlet of the liquid inlet pump 20 is connected to the recovery device 50 through a branch, and the flow direction of the wastewater is controlled by a control valve, so that the wastewater in the wastewater tank 10 can be directly circulated and filtered through the recovery device 50.

[0064] In a preferred embodiment, the oily wastewater treatment system further includes a control system to automatically control the operating state of the oily wastewater treatment system. For example, the control system can adopt a PLC control system, equipped with an editable controller, a touch screen, and interlocking control of a feed pump, a liquid level meter 11, a control valve, a regulating valve, a pressure transmitter 80, a differential pressure transmitter, a flow meter 70, etc., to achieve one-button start, automatic filtering and oil collection, automatic flushing, automatic flow adjustment, high pressure alarm, high pressure differential alarm reminder, low liquid level shutdown and other functions.

[0065] In a preferred embodiment, the oily wastewater treatment system is modularly configured, and each system is integrated with a skid. The customer only needs to provide the main power supply to the control cabinet and connect the process pipeline nozzles to each nozzle to operate it. The installation is convenient and fast, saving on-site assembly time, and the installation location can also be quickly transferred according to project requirements.

[0066] [Example 2]

[0067] This embodiment provides a control method for an oily wastewater treatment system, in which the start and stop of the water-oil separation program is automatically controlled according to the amount of wastewater in the wastewater tank 10. Specifically, when the wastewater level is less than or equal to the first level, the water-oil separation program is automatically stopped; in the shutdown state, when the wastewater level is greater than or equal to the second level, the water-oil separation program is automatically started.

[0068] The control method provided in this embodiment also includes automatically switching the operating state of the pretreatment device 31 according to the flux of the pretreatment device 30. Specifically, the flux of the pretreatment device 30 is judged according to the inlet and outlet pressure difference of the pretreatment device 31, and when the inlet and outlet pressure difference of the pretreatment device 31 is greater than or equal to a preset value, the currently running pretreatment device 30 is automatically switched to the backwash mode, and another set of pretreatment devices 30 is started to participate in the operation of the water-oil separation program.

[0069] The control method provided in this embodiment also includes adjusting the operating power of the liquid inlet pump 20 according to the liquid inlet pressure and / or the water phase outlet flow rate of the water-oil separation device 40.

[0070] In some embodiments, when the pressure at the inlet of the water-oil separator 40 is higher than a set threshold, the operating power of the inlet pump 20 tends to decrease to reduce the inlet pressure and ensure safe operation; when the pressure at the inlet of the water-oil separator 40 is lower than the set threshold, the operating power of the inlet pump 20 tends to increase to increase the inlet pressure and increase the speed of water-oil separation. Exemplarily, the range of the set threshold is between 0.1-0.4MPa, preferably between 0.2-0.3MPa, and more preferably 0.25MPa.

[0071] In some embodiments, when the water phase outlet flow rate is greater than the first flow rate, the operating power of the liquid inlet pump 20 tends to decrease to reduce the wastewater supply, ensure operational safety, and prevent water from flowing out of the oil phase outlet; when the water phase outlet flow rate is less than the first flow rate, the operating power of the liquid inlet pump 20 tends to increase to increase the wastewater supply and ensure the water-oil separation efficiency.

[0072] In some embodiments, before adjusting the operating power of the liquid inlet pump 20, the inlet and outlet pressure differential of the water-oil separation device 40 is also obtained. If the pressure differential is greater than the set range, it means that the separation membrane group 42 of the water-oil separation device 40 is blocked and the separation membrane group needs to be replaced. In this case, it is prompted to replace the separation membrane group, and the operating power of the liquid inlet pump 20 will be reduced or the liquid inlet pump 20 will be directly shut down.

[0073] In some embodiments, the above methods for adjusting the operating power of the inlet pump are taken into consideration.

[0074] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0075] The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this patent can make some changes or modifications to equivalent embodiments of equivalent changes by using the technical content suggested above without departing from the scope of the technical solution of the present invention. The implementation scheme in the above embodiment can also be further combined or replaced. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the solution of the present invention.

Claims

1. An oily wastewater treatment system, characterized in that: include: A wastewater tank is used to store oily wastewater to be treated, and a liquid level meter is provided therein to monitor the liquid level of the wastewater tank in real time; A liquid inlet pump, used for pumping the oily wastewater in the wastewater tank, wherein the inlet of the pump is connected to the outlet of the wastewater tank; The pretreatment device is used to pre-separate solids and colloidal suspended matter in the wastewater. Its liquid inlet is connected to the outlet of the liquid inlet pump, and includes two sets of pretreatment equipment connected in parallel. The two sets of pretreatment equipment can be switched to operate independently, and each set of pretreatment equipment is equipped with a differential pressure gauge; The water-oil separation device is used to separate water and oil in wastewater, and is provided with a water phase outlet and an oil phase outlet. Its liquid inlet is connected to the liquid outlet of the pretreatment device. The water-oil separation device is provided with a differential pressure gauge, and its water phase outlet is provided with a flow meter.

2. The oily wastewater treatment system according to claim 1, characterized in that: It also includes a recovery device, wherein the waste outlets of the pretreatment device and the water-oil separation device are respectively connected to the liquid inlet of the recovery device, the liquid outlet of the recovery device is connected to the inlet of the wastewater tank, and a filter component is provided between the liquid inlet and the liquid outlet of the recovery device.

3. The oily wastewater treatment system according to claim 1, characterized in that: The water-oil separation device comprises a shell, the water phase outlet and the oil phase outlet are arranged on the shell, and are located downstream of the separation membrane group. The water phase outlet is arranged at the lower part of the shell, and the oil phase outlet is arranged at the upper part of the shell. A separation membrane group is arranged inside the shell.

4. The oily wastewater treatment system according to claim 3, characterized in that: An oil collecting pipe is vertically arranged on the upper part of the shell, an oil phase outlet is arranged on the top of the oil collecting pipe, and an interface meter is arranged on the side of the oil collecting pipe for monitoring the position of the oil-water interface in the oil collecting pipe.

5. The oily wastewater treatment system according to claim 3, characterized in that: A fluid distributor is provided between the liquid inlet of the water-oil separation device and the separation membrane group.

6. The oily wastewater treatment system according to claim 1, characterized in that: It also includes a backwashing device, including a compressed air module and a backwashing water module. Each set of pretreatment equipment is provided with a backwashing port, and the backwashing device is respectively connected to the backwashing port of each set of pretreatment equipment.

7. The oily wastewater treatment system according to any one of claims 1 to 6, characterized in that: It also includes a control system for automatically controlling the operating status of the oily wastewater treatment system.

8. A control method for an oily wastewater treatment system, characterized in that: Automatically control the start and stop of the water-oil separation process according to the amount of wastewater in the wastewater tank; In the running state, when the wastewater level is less than or equal to the first level, the water-oil separation process automatically stops; In the shutdown state, when the wastewater level is greater than or equal to the second level, the water-oil separation program starts automatically.

9. The control method of the oily wastewater treatment system according to claim 8, characterized in that: Automatically switch the operating state of the pretreatment equipment according to the flux of the pretreatment device; Determine the flux of the pretreatment device based on the inlet and outlet pressure difference of the pretreatment device; When the inlet and outlet pressure difference of the pretreatment equipment is greater than or equal to the preset value, the currently running pretreatment device automatically switches to the backwash mode, and the other pretreatment device starts to participate in the operation of the water-oil separation program.

10. The control method of the oily wastewater treatment system according to claim 8, characterized in that: The operating power of the liquid inlet pump is adjusted according to the liquid inlet pressure and / or the water phase outlet flow rate of the water-oil separation device.

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