Sewage treatment system of gas collection station

Abstract

The utility model relates to the technical field of gas collection station sewage treatment, in particular to a gas collection station sewage treatment system which comprises a three-phase separator, an oil flotation tank and a plate-and-frame filter press, the three-phase separator is connected with a buffer tank, a lifting pump and a dispersion pump are arranged between the buffer tank and the oil flotation tank, and the plate-and-frame filter press is connected with the oil flotation tank. The oil flotation tank is connected with the purified water tank through the primary filter and the secondary filter; the oil flotation tank is further connected with a sludge tank, a pressure stirring tank is arranged between the sludge tank and the plate-and-frame filter press, the sludge tank is connected with the pressure stirring tank through a sludge pump, the pressure stirring tank is further connected with an air compressor, and the plate-and-frame filter press is connected with an oil-water separator. And the oil-water separator is also connected with the pipeline between the three-phase separators and the buffer tank. Oil-containing sewage is treated by utilizing an oil flotation process of the oil flotation tank, so that the device can adapt to sewage with different emulsified oil contents, the oil subjected to filter pressing by the plate-and-frame filter press is purified, and the oil product of the recovered oil is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of sewage treatment in gas gathering stations, and particularly relates to a sewage treatment system for gas gathering stations. Background Technique

[0002] At present, gas gathering stations in China collect oil, gas, and water generated by each gas well, and then conduct three-phase separation, that is, separate oil, gas, and water. The gas is transported to the external transmission pipeline network through the natural gas pipeline; the oil and water are transported by tanker trucks to the water treatment station for further treatment, and the treated water is reinjected into the deep underground. Some gas gathering stations also treat the sewage, and the treated water is reinjected into the formation on the station. The above process has some problems:

[0003] 1. The sewage separated by three-phase separation in the gas gathering station, because it only undergoes simple physical treatment, still has a high oil content in the water and belongs to hazardous waste.

[0004] 2. For on-site sewage treatment, there are currently two main treatment methods. One is air flotation, and the other is coagulation sedimentation. The air flotation process requires aeration of the sewage, and aeration will increase the dissolved oxygen in the sewage, increasing the corrosiveness of the sewage; aeration in the oil and gas field will bring potential safety hazards and increase the safety risk in the station; in addition, during aeration, oil and gas will be brought into the environment due to the air-lift effect, causing environmental pollution. When using the coagulation sedimentation process, because the sewage contains emulsified oil, when the oil content of the emulsified oil is very high (>300 PPM), it will cause the generated sludge to float, making the sedimentation process ineffective and the water quality unable to meet the standard of reinjected water.

[0005] 3. At present, most of the sludge generated from the treatment of oily sewage is treated by a spiral sludge dewatering machine or a centrifugal sludge dewatering machine. The moisture content of the dried sludge after this process is at least 80% at the lowest, and the oil cannot be removed. The disposal of dried sludge is a major problem in gas fields.

[0006] 4. If the sewage in the gas gathering station cannot be reinjected locally, it will greatly increase the transportation cost of sewage treatment. Especially when it is identified as hazardous waste, its transportation cost is even higher, increasing the production cost of the gas field.

[0007] The gas gathering station is a main link in the production of oil and gas fields, and its operation quality is related to the production and operation costs of oil and gas fields. Therefore, it is very necessary and meaningful to develop a sewage treatment system for gas gathering stations to solve the existing problems and promote the development of oil and gas fields. Summary of the Invention

[0008] The main purpose of the utility model is to provide a sewage treatment system for gas gathering stations, which can effectively solve the problems in the background technique.

[0009] To achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0010] A sewage treatment system for a gas gathering station, comprising a three-phase separator, an oil flotation tank and a plate and frame filter press. The three-phase separator is connected to a buffer tank. A lift pump and a dispersion pump are provided between the buffer tank and the oil flotation tank. The oil flotation tank is connected through a primary filter, a secondary filter and a purified water tank; the oil flotation tank is also connected to a sludge tank, and a pressure stirring tank is provided between the sludge tank and the plate and frame filter press.

[0011] By adopting the above technical solution, the oil flotation process of the oil flotation tank is used to treat oily sewage, which can adapt to sewage with different oil content rates of emulsified oil. When the oil content rate of emulsified oil in the incoming water > 300 ppm, it is not necessary to add condensate oil to make the sludge float, ensuring the normal operation of the oil flotation tank; when the oil content rate of emulsified oil in the incoming water < 300 ppm, condensate oil can be added to make all the sludge float, ensuring the normal operation of the oil flotation tank; the sewage treated by the oil flotation process of the oil flotation tank meets the standard of reinjection water and can be directly reinjected into the formation at the gas gathering station, saving a large amount of sewage transportation costs.

[0012] Specifically, the sludge tank is connected to the pressure stirring tank through a sludge pump, and the pressure stirring tank is also connected to an air compressor.

[0013] Specifically, the plate and frame filter press is connected to an oil-water separator, the oil-water separator is connected to a sewage recovery pump, and the oil-water separator is also connected to the pipeline between the buffer tank and the three-phase separator.

[0014] Specifically, the buffer tank is also connected to a condensate oil tank, and the condensate oil tank is connected to an oil tanker through an oil pump.

[0015] Specifically, a fuel pump is connected between the lift pump and the dispersion pump, and the oil flotation tank is connected to a fourth chemical dosing pump.

[0016] Specifically, a first chemical dosing pump, a second chemical dosing pump and a third chemical dosing pump are also connected between the dispersion pump and the oil flotation tank.

[0017] The beneficial effects of the present utility model:

[0018] The sewage treatment system for a gas gathering station described in the present utility model uses the oil flotation process of the oil flotation tank to treat oily sewage, which can adapt to sewage with different oil content rates of emulsified oil. When the oil content rate of emulsified oil in the incoming water > 300 ppm, it is not necessary to add condensate oil to make the sludge float, ensuring the normal operation of the oil flotation tank; when the oil content rate of emulsified oil in the incoming water < 300 ppm, condensate oil can be added to make all the sludge float, ensuring the normal operation of the oil flotation tank; the sewage treated by the oil flotation process of the oil flotation tank meets the standard of reinjection water and can be directly reinjected into the formation at the gas gathering station, saving a large amount of sewage transportation costs;

[0019] For the sewage treatment system of a gas gathering station described in the present utility model, the oil flotation process is a fully enclosed process, without discharging gas into the environment and causing no secondary pollution to the environment, thus maintaining a good environment. The water content of the treated sludge is < 70%, and the sludge volume is reduced by 33% compared with that of a sludge moisture content of 80% such as a spiral press, which is equivalent to a 33% reduction in sludge disposal costs. The oil is purified after being filtered by a plate and frame filter press, improving the quality of the recovered oil. Brief Description of the Drawings

[0020] The present utility model will be further described below in conjunction with the drawings and embodiments.

[0021] Figure 1 It is a schematic structural diagram of a sewage treatment system for a gas gathering station of the present utility model.

[0022] In the figure: 1. Three-phase separator; 2. Buffer tank; 3. Lift pump; 4. Dispersion pump; 5. Oil flotation tank; 6. First-stage filter; 7. Second-stage filter; 8. Purified water tank; 9. Fuel pump; 10. First chemical dosing pump; 11. Second chemical dosing pump; 12. Third chemical dosing pump; 13. Fourth chemical dosing pump; 14. Oil tanker; 15. Oil pump; 16. Condensate oil tank; 17. Sludge tank; 18. Sludge pump; 19. Pressure stirring tank; 20. Air compressor; 21. Oil-water separator; 22. Sewage recovery pump; 23. Plate and frame filter press. Specific Embodiments

[0023] In order to make the technical means, creative features, achieved purposes and functions of the present utility model easy to understand, the present utility model will be further described below in conjunction with specific embodiments.

[0024] As Figure 1 shown, a sewage treatment system for a gas gathering station includes a three-phase separator 1, an oil flotation tank 5 and a plate and frame filter press 23. The three-phase separator 1 is connected to the buffer tank 2. A lift pump 3 and a dispersion pump 4 are provided between the buffer tank 2 and the oil flotation tank 5. The oil flotation tank 5 is connected through a first-stage filter 6, a second-stage filter 7 and a purified water tank 8. The oil flotation tank 5 is also connected to the sludge tank 17, and a pressure stirring tank 19 is provided between the sludge tank 17 and the plate and frame filter press 23.

[0025] As an implementation mode of the utility model, the sludge tank 17 is connected to the pressure stirring tank 19 through a sludge pump 18, and the pressure stirring tank 19 is also connected to an air compressor 20; the plate and frame filter press 23 is connected to the oil-water separator 21, the oil-water separator 21 is connected to a sewage recovery pump 22, and the oil-water separator 21 is also connected to the pipeline between the buffer tank 2 and the three-phase separator 1; the buffer tank 2 is also connected to the condensate oil tank 16, and the condensate oil tank 16 is connected to an oil tanker 14 through an oil pump 15; a fuel pump 9 is connected between the lift pump 3 and the dispersion pump 4, and the oil flotation tank 5 is connected to a fourth chemical dosing pump 13; a first chemical dosing pump 10, a second chemical dosing pump 11 and a third chemical dosing pump 12 are also connected between the dispersion pump 4 and the oil flotation tank 5.

[0026] The sludge discharged from the sludge tank 17 is dehydrated and deoiled through the plate and frame filter press 23. After pressure filtration, the water content of the sludge is < 70% and the oil content is < 2%, meeting the discharge requirements of the oilfield industry; the sludge volume with a water content of 70% after pressure filtration by the plate and frame filter press 23 is 33% less than the sludge volume with a water content of 80% after pressure filtration by the spiral press filter.

[0027] The plate and frame filter press 23 can recover the oil in the sewage and the added condensate oil, and the recovered oil can also be purified; the oil flotation water quality process of the oil flotation tank 5 can lift all the generated sludge to the top of the oil flotation tank 5 without the phenomenon of sludge sinking, thus ensuring the normal operation of the oil flotation tank 5.

[0028] It should be noted that the utility model is a gas gathering station sewage treatment system. The oily sewage and oil separated by the three-phase separator 1 of the gas gathering station from the well-discharged liquid enter the buffer tank 2, where the gas in the water is released, the floating oil in the sewage is recovered, and the sewage is lifted by the lift pump 3. At the same time, condensate oil is added through the condensate oil tank 16 (if the sewage contains high emulsified oil, condensate oil may not be added), and then demulsifier, pH regulator, and coagulant are added. The sewage enters the oil flotation tank 5, where it is mixed and reacted, and the flocs formed by the chemicals adsorb impurities, oil, etc. in the sewage; and flocculant is added in the later stage to facilitate the growth of the flocs. Through the special structure of the sludge collection tank of the oil flotation tank 5, the flocs are separated from the water, and the sewage is purified. The purified sewage directly enters the first-stage filter 6 and the second-stage filter 7 from the bottom of the oil flotation tank 5. After filtration, it enters the purified water tank 8; the floating flocs reach the top of the oil flotation tank to form sludge, and rely on the self-pressure of the oil flotation tank to be discharged to the sludge tank 17.

[0029] The foregoing has shown and described the basic principles, main features and advantages of the present utility model. Those skilled in the art should understand that the present utility model is not limited by the above-mentioned embodiments. The above-mentioned embodiments and the description in the specification only illustrate the principles of the present utility model. Without departing from the spirit and scope of the present utility model, the present utility model will have various changes and improvements, and all these changes and improvements fall within the scope of the present utility model claimed. The scope of protection claimed by the present utility model is defined by the appended claims and their equivalents.

Claims

1. A gas gathering station sewage treatment system, characterized in that: It comprises a three-phase separator (1), an oil flotation tank (5) and a plate-frame filter press (23), wherein the three-phase separator (1) is connected to a buffer tank (2), a lifting pump (3) and a dispersion pump (4) are provided between the buffer tank (2) and the oil flotation tank (5), and the oil flotation tank (5) is connected via a primary filter (6), a secondary filter (7) and a purified water tank (8); The oil flotation tank (5) is also connected to a sludge tank (17), and a pressure stirring tank (19) is provided between the sludge tank (17) and the plate and frame filter press (23).

2. A gas gathering station sewage treatment system according to claim 1, characterized in that: The sludge tank (17) is connected to a pressure stirring tank (19) via a sludge pump (18), and the pressure stirring tank (19) is also connected to an air compressor (20).

3. A gas gathering station sewage treatment system according to claim 1, characterized in that: The plate-and-frame filter press (23) is connected to an oil-water separator (21), the oil-water separator (21) is connected to a sewage recovery pump (22), and the oil-water separator (21) is also connected to a pipeline between the buffer tank (2) between the three-phase separator (1).

4. A gas gathering station sewage treatment system according to claim 1, characterized in that: The buffer tank (2) is also connected to a condensate oil tank (16), and the condensate oil tank (16) is connected to an oil tanker (14) via an oil pump (15).

5. A gas gathering station sewage treatment system according to claim 1, characterized in that: A refueling pump (9) is connected between the lifting pump (3) and the dispersion pump (4), and the oil flotation tank (5) is connected to a fourth dosing pump (13).

6. A gas gathering station sewage treatment system according to claim 1, characterized in that: A first dosing pump (10), a second dosing pump (11) and a third dosing pump (12) are also connected between the dispersion pump (4) and the oil flotation tank (5).

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