Oil-water separation and recovery system of sewage treatment device

Abstract

The present invention relates to an oil-water separation and recovery system for a sewage treatment device. It mainly solves the problem that the sewage after treatment by the existing sewage treatment device still contains light oil, resulting in non-compliance of sewage discharge standards and also a large loss of light oil products. Its characteristics are as follows: The oil-containing sewage inlet pipeline (15) is connected to two-stage oil removal tanks and an oil-water separation tank body (1); the oil-water separation tank body (1) is a closed storage tank; an oil-water inlet pipe orifice (2) is provided at the bottom of the oil-water separation tank body (1), and the oil-water inlet pipe orifice (2) is connected to an L-shaped oil-water inlet pipe; the longitudinal part of the oil-water inlet pipe is located at the axial center of the tank body; the top of the oil-water inlet pipe is connected to an oil-water distribution assembly. This system can separate the oil contained in the sewage into oil and water, obtain qualified sewage at the bottom of the oil-water separator, and recover the oil quality at the top of the oil-water separator, reducing the light oil quality in the sewage to 2-3 ppm and improving the current situation of environmental pollution.

Description

Technical Field

[0001] The present invention relates to the technical field of water conservation and environmental protection compliance in public engineering systems of oil refining and chemical plants, and in particular to an oil-water separation and recovery system for a sewage treatment plant. Background Art

[0002] The vast amount of wastewater generated during petrochemical production is continuously transported to sewage treatment facilities. Currently, most domestic sewage treatment plants use traditional treatment methods, employing multiple large oil separators and regulating tanks to allow natural sedimentation and separation of oily wastewater. However, even after treatment, the wastewater still contains 40-50 mg / L of light oil. Due to the lack of oil-water separation facilities in subsequent processes, the oily wastewater is discharged into the sewage system through outfalls. This results in substandard wastewater discharge, significant amounts of light oil products being lost, and resource loss. Because current sewage treatment technology cannot meet discharge requirements, wastewater discharge pollutes the environment, failing to meet environmental standards and becoming a challenge to compliant production. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the problem in the background technology that a large amount of wastewater generated in the existing production process is continuously transported to the sewage treatment device, and the treated sewage still contains light oil, resulting in sewage discharge not meeting the standards and also losing a large amount of light oil products. A sewage treatment device oil-water separation and recovery system is provided. The sewage treatment device oil-water separation and recovery system can achieve sewage quality improvement and discharge, improve the current situation of environmental pollution, lay the foundation for the compliant production of the device, and at the same time recover a large amount of oil carried in the sewage.

[0004] The present invention solves the problem through the following technical solution: the oil-water separation and recovery system of the sewage treatment device includes an oily sewage inlet pipeline, which is connected to a two-stage oil removal tank and an oil-water separation tank body; the oil-water separation tank body is a closed storage tank; an oil-water inlet pipe port is provided at the bottom of the oil-water separation tank body, and the oil-water inlet pipe port is connected to an L-shaped oil-water inlet pipe; the longitudinal part of the oil-water inlet pipe is located in the axial center of the tank body; the top of the oil-water inlet pipe is connected to an oil-water distribution assembly.

[0005] Furthermore, the oil-water distribution assembly includes several horizontally arranged oil-water distribution branches; the center point of the oil-water distribution branch is connected to the top of the oil-water inlet pipe; and both ends of the oil-water distribution branch are connected to several oil-water distributors through short joints.

[0006] Furthermore, there are 3-6 oil-water distribution branches.

[0007] Furthermore, the number of the oil-water distributors is 18-36.

[0008] Further, a fuel tank is provided on one side corresponding to the upper part of the oil-water distributor and above the oil-water separation tank body. The bottom of the fuel tank is connected to an L-shaped oil discharge pipe, and the outlet end of the oil discharge pipe faces the outside of the tank body. A horizontal drain pipe is also connected to the bottom of the oil-water separation tank body.

[0009] Further, an "inverted U-shaped" overflow pipe is provided on one side inside the oil-water separation tank body. The end of the inlet section of the overflow pipe abuts against the bottom of the oil-water separation tank body. An inlet is opened in the lower part of the inlet section of the overflow pipe. An exhaust port is provided at the highest point of the overflow pipe. The outlet section of the overflow pipe is horizontally connected to the outlet of the overflow pipe, and the outlet of the overflow pipe is located above the oil-water inlet pipe.

[0010] Further, a drain pipe is provided at the bottom of the oil-water separation tank body, and the drain pipe is located below the oil-water inlet pipe.

[0011] Further, the height ratios of the exhaust port at the highest point of the overflow pipe, the fuel tank, the oil-water distributor, and the inlet from the bottom of the tank body are 6.5: 5.5 - 6.0: 4.5 - 5.0: 1.0 - 0.5.

[0012] Further, the two-stage oil removal tank includes oil removal tank A and oil removal tank B. The oil-containing sewage inlet pipeline is connected to the bottom of oil removal tank A. The first oil-containing sewage outflow pipeline in the upper middle part of oil removal tank A is connected to the bottom of oil removal tank B. The second oil-containing sewage outflow pipeline in the upper middle part of oil removal tank B is connected to the oil-water separation tank body through the oil-water inlet pipe.

[0013] The present invention may have the following beneficial effects when compared with the above background technology:

[0014] The oil-water distributor provided in the system of the present invention allows the oil-containing wastewater to flow out horizontally, preventing the water flow from rising and disturbing the upper oil surface. An overflow pipe is provided inside the oil-water separation tank body. An inlet is opened in the lower part of the inlet section of the overflow pipe, so as to discharge the tank body in time when the liquid level in the tank is too high. Since the overflow inlet is provided at the bottom of the separation tank, the excess oil-free sewage inside the tank body can be successfully discharged. An exhaust port is provided at the highest point of the overflow pipe to exhaust gas and facilitate the flow of water.

[0015] The height ratios of the exhaust port at the highest point of the overflow pipe, the fuel tank, the oil-water distributor, and the inlet from the bottom of the tank body are arranged in a decreasing order, which is convenient for simple and efficient oil-water separation.

[0016] Using the oil-water separation and recovery system of the sewage treatment device of the present invention, the sewage is discharged up to standard and with improved quality, improving the current situation of environmental pollution, laying a foundation for the compliant production of the device, and at the same time recovering a large amount of oil in the sewage.

[0017] In on-site applications, after separating 40 tons / h of sewage containing 50 ppm of light oil through the invented oil-water separation tank, the light oil in the sewage is reduced to 2-3 ppm; at the same time, a large amount of oil in the sewage is recovered, with a recovery volume of 172.8 tons / year. Through this invention, not only the sewage discharge quality meets the standards, but also a large amount of light oil is recovered, creating a profit of more than one million yuan. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. Figure 1 is the system flow chart of the present invention;

[0019] FIG. Figure 2 is the structural schematic diagram of the oil-water separation tank body of the present invention;

[0020] FIG. Figure 3 is the top view of the oil-water separation tank body of the present invention.

[0021] In the figure: 1 - oil-water separation tank body; 2 - oil-water inlet pipe; 3 - oil-water distribution branch pipe; 4 - oil-water distributor; 5 - oil collection tank; 6 - oil discharge pipe; 7 - drain pipe; 8 - water inlet; 9 - high point exhaust port of overflow pipe; 10 - outlet of overflow pipe; 11 - emptying pipe; 12 - overflow pipe; 13 - oil removal tank A; 14 - oil removal tank B; 15 - oil-containing sewage inlet pipeline; 16 - first oil-containing sewage outflow pipeline; 17 - second oil-containing sewage outflow pipeline. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The present invention will be further described below in conjunction with the accompanying drawings:

[0023] As shown in FIG. Figure 1 The oil-water separation and recovery system of the sewage treatment device includes an oil-containing sewage inlet pipeline 15, and the oil-containing sewage inlet pipeline 15 is connected to the bottom of the oil removal tank A 13; the first oil-containing sewage outflow pipeline 16 in the upper middle part of the oil removal tank A 13 is connected to the bottom of the oil removal tank B 14; the second oil-containing sewage outflow pipeline 17 in the upper middle part of the oil removal tank B 14 is connected to the oil-water separation tank body 1 through the oil-water inlet pipe 2.

[0024] As shown in Figure 2 、 Figure 3As shown, the top of the oil-water separation tank body 1 is an arc-shaped tank top; the top of the oil-water separation tank body 1 is a closed storage tank; the bottom of the oil-water separation tank body 1 is provided with an oil-water inlet pipe opening 2, and the oil-water inlet pipe opening 2 is connected to an L-shaped oil-water inlet pipe. The longitudinal part of the oil-water inlet pipe is at the axial center of the tank body. The top of the oil-water inlet pipe is connected to the center points of 3 - 6 horizontally arranged oil-water distribution branch pipes 3; both ends of the oil-water distribution branch pipe 3 are respectively connected to 18 - 36 oil-water distributors 4 through short joints. The oil-water distributors 4 flow out the oil-containing wastewater horizontally to prevent the water flow from rising and disturbing the upper oil surface; on one side of the oil-water separation tank body 1 corresponding to the upper part of the oil-water distributor 4, there is an oil collection tank 5. The bottom of the oil collection tank 5 is connected to an L-shaped oil discharge pipe 6. The outlet end of the oil discharge pipe 6 faces the outside of the tank body 1. The light oil separated and recovered by the oil collection tank is discharged through the oil discharge pipe to the fixed-point recovery position; the bottom of the oil-water separation tank body 1 is also connected with a horizontal drain pipe 7, whose function is to continuously discharge the oil-free sewage from the bottom of the tank; in order to prevent overpressure in the oil-water separation tank when it is full, an "inverted U-shaped" overflow pipe 12 is also arranged on one side inside the oil-water separation tank body 1; the end of the inlet section of the overflow pipe 12 abuts against the bottom of the oil-water separation tank body 1; a water inlet 8 is opened at the lower part of the inlet section of the overflow pipe 12, so as to discharge the tank body in time when the liquid level in the tank is too high. Since the overflow water inlet 8 is arranged at the bottom of the separation tank, the excess oil-free sewage inside the tank body can be successfully discharged; an exhaust port 9 at the high point of the overflow pipe 12 is provided to exhaust air and discharge water in time; the outlet section of the overflow pipe 12 is horizontally connected to an overflow pipe outlet 10, and the overflow pipe outlet 10 is located above the oil-water inlet pipe opening 2; a drain pipe 11 is arranged at the bottom of the tank, and the drain pipe 11 is located below the oil-water inlet pipe opening 2, which is convenient for discharging the sewage in the tank smoothly during maintenance and tank cleaning.

[0025] The height ratios of the exhaust port 9 at the high point of the overflow pipe, the oil collection tank 5, the oil-water distributor 4, and the water inlet 8 from the bottom of the tank body are 6.5: 5.5 - 6.0:4.5 - 5.0:1.0 - 0.5; this decreasing proportional relationship is convenient for simple and efficient oil-water separation.

[0026] The treatment process of the oil-water separation and recovery system of this sewage treatment device is as follows:

[0027] Mixed oily wastewater from the site enters de-oiling tank A13 from the bottom. Sedimentation and stratification occur within the de-oiling tank using the difference in oil and water density. After stratification, the oil phase is located at the top of the tank, and the water phase is located in the middle and upper part of the tank. The water phase flows out of the middle and upper part of de-oiling tank A13 and then enters de-oiling tank B14 from the bottom. Sedimentation and stratification occur again within de-oiling tank A13 and B14 before flowing out of the middle and upper part of de-oiling tank B14 and entering the oil-water separation tank for further oil-water separation. After two sedimentation and separations in de-oiling tanks A13 and B14, the wastewater enters the newly invented oil-water separation tank 1. The wastewater first enters the oil-water distribution branch pipe 3 through the water inlet 2, and then enters the various oil-water distributors 4 through the oil-water distribution branch pipes. The oil-water mixture that has passed through the oil-water distributors is more easily separated due to the difference in density, and the oil-water mixture that flows out of the oil-water distributors 4 continuously falls to the bottom of the tank. The density of light oil is 0.78 kg / m³, while the density of water is 1.0 kg / m³. Due to this density difference, the oil and water separate into separate layers within the tank. As the liquid level in the continuous feed tank continues to rise, the oil level at the top of the tank also rises. When the oil level reaches the inlet of the oil collecting tank 5, the oil phase flows into the oil collecting tank 5 and is discharged through the connected oil drain pipe 6 to a designated location such as an oil storage tank. The oil-free wastewater at the bottom of the separation tank is discharged to a designated reservoir through drain pipe 7. To prevent excessive pressure during operation of the oil-water separation tank 1, an overflow pipe is installed inside the tank. The oil-free wastewater at the bottom of the tank enters the overflow pipe inlet 8, is exhausted through the high-point vent pipe 9, and then flows to the overflow pipe outlet 10. Finally, through the overflow pipe outlet 10, it is discharged to a designated location such as a sewage tank. The overflow pipe's high point is located at the top of the pipe. Based on the principle of a communicating vessel, when the tank liquid level is below the high point of the overflow pipe, the bottom water level will not overflow. Through the implementation of this invention and transformation, the oily wastewater is well separated and significant results are achieved.

[0028] The wastewater treatment plant of Daqing Zhonglan Petrochemical Co., Ltd. has a designed treatment capacity of 100 tons / h. Only the nonene plant, MTBE plant, oil product plant and laboratory generate wastewater, with a wastewater flow rate of 40 tons / h.

[0029] Before Daqing Zhonglan Petrochemical Co., Ltd. applied this technology, the wastewater generated by the nonene unit, MTBE unit, oil product unit and laboratory still contained 40-50ppm of oil after deoiling in the unit's original oil removal tanks A13 and B14, which did not meet the wastewater discharge standards. Moreover, the discharge of substandard oily wastewater polluted the environment and caused serious light oil losses, with a loss of 0.02 tons per hour and a daily loss of 0.48 tons simply due to the oil carried in the wastewater.

[0030] Daqing Zhonglan Petrochemical Co., Ltd. has effectively recovered light oil carried in sewage by applying the present invention for optimization and transformation, with a recovery rate of 0.02 tons / h. The annual production period is calculated as 360 days: the light oil sales are 6,000 yuan / ton.

[0031] Annual recovered light oil: 0.02 tons / h * 24 h / day * 360 days = 172.8 tons;

[0032] Cost savings: 172.8 tons × 6,000 yuan / ton = 1,036,800 yuan;

[0033] The oil-water separation and recovery system of this sewage treatment device meets both safety and environmental protection requirements and achieves cost savings.

Claims

1. An oil-water separation and recovery system for a sewage treatment plant, comprising an oily sewage inlet pipeline (15), characterized in that: The oily wastewater inlet pipeline (15) is connected to the two-stage oil removal tank and the oil-water separation tank body (1); the oil-water separation tank body (1) is a closed storage tank; an oil-water inlet pipe opening (2) is provided at the bottom of the oil-water separation tank body (1), and the oil-water inlet pipe opening (2) is connected to an L-shaped oil-water inlet pipe; the longitudinal portion of the oil-water inlet pipe is located at the axial center of the oil-water separation tank body; the top of the oil-water inlet pipe is connected to an oil-water distribution assembly; The oil-water distribution assembly comprises a plurality of horizontally arranged oil-water distribution branch pipes (3); the center point of the oil-water distribution branch pipe (3) is connected to the top of the oil-water inlet pipe; the two ends of the oil-water distribution branch pipe (3) are respectively connected to a plurality of oil-water distributors (4) through short joints; An oil collecting tank (5) is provided on the upper part of the oil-water distributor (4) corresponding to one side of the oil-water separation tank body. The bottom of the oil collecting tank (5) is connected to an L-shaped oil drain pipe (6), and the outlet end of the oil drain pipe (6) faces the outside of the oil-water separation tank body. The bottom of the oil-water separation tank body (1) is also connected to a horizontal drain pipe. An "inverted U-shaped" overflow pipe (12) is further provided on one side of the oil-water separation tank body (1); the end of the inlet section of the overflow pipe (12) abuts against the bottom of the oil-water separation tank body (1); a water inlet (8) is provided at the lower portion of the inlet section of the overflow pipe (12); the outlet of the outlet section of the overflow pipe (12) is horizontally connected to the overflow pipe outlet (10), and the overflow pipe outlet (10) is located above the oil-water inlet pipe (2); The overflow pipe (12) is provided with an overflow pipe high point exhaust port (9) at a high point; The height ratios of the overflow pipe high point exhaust port (9), the oil collecting tank (5), the oil-water distributor (4), and the water inlet (8) to the bottom of the oil-water separation tank are 6.5: 5.5-6.0: 4.5-5.0: 1.0-0.

5.

2. The oil-water separation and recovery system for a sewage treatment plant according to claim 1, characterized in that: The number of the oil-water distribution branch pipes (3) is 3-6.

3. The oil-water separation and recovery system for a sewage treatment plant according to claim 1, characterized in that: The number of the oil-water distributors (4) is 18-36.

4. The oil-water separation and recovery system for a sewage treatment plant according to claim 1, characterized in that: A drain pipe (11) is provided at the bottom of the oil-water separation tank (1).

5. The oil-water separation and recovery system for a sewage treatment plant according to claim 4, characterized in that: The drain pipe is located at the lower part of the oil and water inlet pipe (2).

6. The oil-water separation and recovery system for a sewage treatment plant according to claim 1, characterized in that: The two-stage oil removal tank comprises an oil removal tank A (13) and an oil removal tank B (14); the oily wastewater inlet pipeline (15) is connected to the bottom of the oil removal tank A (13); the first oily wastewater outflow pipeline (16) in the middle and upper part of the oil removal tank A (13) is connected to the bottom of the oil removal tank B (14); the second oily wastewater outflow pipeline (17) in the middle and upper part of the oil removal tank B (14) is connected to the oil-water separation tank body through the oil-water inlet pipe (2).

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