Metering tank for separating and metering

Abstract

The utility model provides a metering tank for separation and metering, which comprises a tank body, a weir plate assembly is arranged in the tank body, and a chamber of the tank body is divided into a liquid inlet bin, an oil-water separation bin, an oil storage bin and a water storage bin by the weir plate assembly; the liquid inlet bin is provided with a liquid inlet; the liquid inlet bin and the oil-water separation bin are separated through a first weir plate, the oil-water separation bin and the oil storage bin are separated through a second weir plate, and the oil-water separation bin and the water storage bin are separated through a third weir plate; the first weir plate is provided with a first water outlet; the liquid inlet bin is communicated with the oil-water separation bin through a first water outlet; the third weir plate is provided with a second water outlet; the oil-water separation bin is communicated with the water storage bin through a second water outlet; the top wall of the second weir plate is lower than that of the first weir plate; the oil storage bin and the water storage bin are respectively provided with a third water outlet and a fourth water outlet; the liquid inlet, the first water outlet, the second water outlet, the third water outlet and the fourth water outlet are all provided with flowmeters. Separation and metering are carried out synchronously, and metering operation is simplified.

Description

Technical Field

[0001] The utility model relates to the technical field of petrochemical engineering, and particularly relates to a metering tank for separation and metering. Background Art

[0002] In industries such as oil well testing in oil fields, the main function of a metering tank is to assist in metering and environmentally storing the oil and water liquids produced from the formation; however, in the ground metering operations of well testing, working conditions such as low-pressure gas-containing fluids, low-pressure sand-containing fluids, and low-pressure oil-water mixtures are often encountered. Before conducting metering operations on low-pressure and low-production wells, it is necessary to first separate the formation fluids using a separator, and then separately meter the separated oil, water, and sand, which results in complex operations. Content of the Utility Model

[0003] The purpose of the utility model is to provide a metering tank for separation and metering, and the technical problem to be solved is to simplify the metering operation and enable separation and metering to be carried out simultaneously.

[0004] The utility model is achieved through the following technical solutions:

[0005] A metering tank for separation and metering, comprising a tank body. An overflow plate assembly is arranged inside the tank body, and the chamber of the tank body is divided into a liquid inlet chamber, an oil-water separation chamber, an oil storage chamber, and a water storage chamber by the overflow plate assembly;

[0006] A liquid inlet is arranged in the liquid inlet chamber, and the liquid inlet is connected to a liquid inlet pipe; the liquid inlet pipe is used for introducing the fluid to be metered;

[0007] The overflow plate assembly includes a first overflow plate, a second overflow plate, and a third overflow plate;

[0008] The liquid inlet chamber and the oil-water separation chamber are separated by the first overflow plate, the oil-water separation chamber and the oil storage chamber are separated by the second overflow plate, and the oil-water separation chamber and the water storage chamber are separated by the third overflow plate;

[0009] A first drain port is arranged on the first overflow plate; the liquid inlet chamber and the oil-water separation chamber are communicated through the first drain port; the first drain port is used for discharging the oil-water mixture in the liquid inlet chamber;

[0010] A second drain port is arranged on the third overflow plate; the oil-water separation chamber and the water storage chamber are communicated through the second drain port; the second drain port is used for discharging the water in the oil-water separation chamber;

[0011] The top wall of the second overflow plate is lower than the top wall of the first overflow plate;

[0012] A third drain port and a fourth drain port are respectively arranged in the oil storage chamber and the water storage chamber; the third drain port is used for discharging the oil in the oil storage chamber; the fourth drain port is used for discharging the water in the water storage chamber;

[0013] Flow meters are provided at the above-mentioned liquid inlet, first drain outlet, second drain outlet, third drain outlet and fourth drain outlet.

[0014] By separating adjacent compartments through the above-mentioned weir plate assembly, physical isolation of formation fluids during the separation process is ensured. The fluid entering the liquid inlet compartment undergoes sedimentation to separate the oil-water mixture and sand particles. The oil-water mixture flows into the oil-water separation compartment through the first drain outlet. According to the principles of immiscibility of water and oil and their different masses, it stands still and stratifies in the oil-water separation compartment to obtain upper-layer oil and lower-layer water. As the oil-water mixture discharged from the liquid inlet compartment increases, the liquid level in the oil-water separation compartment gradually rises until it overflows. The overflowing upper-layer oil enters the oil storage compartment through the top wall of the second weir plate, and the lower-layer water enters the water storage compartment through the second drain outlet, realizing the separation of water and oil. The integrated treatment process from fluid entry, separation to final storage simplifies the complex process that requires the cooperation of multiple devices in traditional processes. Flow meters are provided at each key position, not only achieving accurate measurement of the fluid volume, but more importantly, enabling the separation and measurement processes to be carried out simultaneously. When the fluid passes through each compartment, its flow rate changes can be recorded in real time, thus ensuring the accuracy of measurement. Since the separation and measurement are carried out simultaneously, errors and time delays that may occur in traditional methods due to step-by-step operations are avoided.

[0015] Furthermore, the above-mentioned first weir plate and second weir plate are vertically arranged inside the tank;

[0016] The above-mentioned first drain outlet is arranged above the top wall of the second weir plate.

[0017] When the oil-water mixture in the above-mentioned liquid inlet compartment enters the oil-water separation compartment through the first drain outlet, due to gravity and the principle of immiscibility of water and oil, the oil and water will start to naturally stratify. And arranging the first drain outlet above the top wall of the second weir plate can prevent the oil-water mixture from flowing back into the liquid inlet compartment and affecting the separation effect. The flow meters arranged at the first drain outlet and the second drain outlet respectively measure the amount of the oil-water mixture entering the oil-water separation compartment and the amount of water entering the water storage compartment. The amount of oil in the oil storage compartment can be obtained based on the difference between the amount of the oil-water mixture and the amount of water, realizing the separation of oil and water and the measurement of the oil volume synchronously.

[0018] Furthermore, the above-mentioned third weir plate is vertically arranged inside the tank;

[0019] The above-mentioned second drain outlet is arranged below the top wall of the second weir plate.

[0020] When the water in the oil-water mixture is much more than the oil, the upper-layer oil only covers the surface of the water. At this time, since the water after stratification is below the oil-water separation tank, the second drain port is set below the top wall of the second weir plate, ensuring that in the oil-water separation tank, after a certain period of residence and stratification, the water can smoothly drain through the second drain port without being interfered by the upper-layer oil, which helps to improve the efficiency and purity of water drainage and reduce the residue of the oil-water mixture; the flowmeter set at the second drain port measures the water volume entering the water storage tank in real time, synchronously realizing oil-water separation and water volume measurement.

[0021] Further, the above-mentioned water storage tank is arranged below the oil-water separation tank;

[0022] The above-mentioned third weir plate is horizontally arranged in the tank body.

[0023] When the oil in the oil-water mixture is more than the water or the water-oil content is about the same, when the water in the lower layer gradually drops in liquid level, it cannot be guaranteed that there must be water at a certain liquid level height. If there is no water at this liquid level height and the second drain port is set at this liquid level height, the oil at this liquid level height will enter the water storage tank, affecting the separation effect; therefore, the third weir plate is horizontally arranged so that the second drain port is located at the bottom of the oil-water separation tank, reducing the influence of the water content in the oil-water mixture on the separation effect.

[0024] Further, the above-mentioned second weir plate is connected with a diversion plate;

[0025] The above-mentioned diversion plate inclines from the top wall of the second weir plate towards the oil storage tank.

[0026] The above-mentioned diversion plate enables the oil separated from the oil-water separation tank to flow more smoothly towards the oil storage tank along the diversion plate, reducing the turbulence and eddy current during the flow of the oil, which helps to maintain the purity and stability of the oil; due to the existence of the diversion plate, the oil will be guided by the diversion plate before entering the oil storage tank through the second weir plate, thus improving the separation efficiency; the diversion plate inclines towards the oil storage tank, which helps to reduce the residue of the oil in the oil-water separation tank or other parts of the tank body, and improve the recovery rate and utilization rate of the oil.

[0027] Further, the upper surface of the above-mentioned diversion plate is concave to form a diversion groove; the above-mentioned diversion groove is used to guide the oil in the upper layer of the oil-water separation tank into the oil storage tank.

[0028] The above-mentioned diversion groove enables the oil separated from the upper layer of the oil-water separation tank to converge more concentratedly in the groove. Since the oil is lighter than water, they will naturally float on the upper layer, and the diversion groove provides a low-resistance path, enabling the oil to flow more easily along the groove wall towards the oil storage tank, enhancing the converging ability of the oil and improving the collection efficiency of the oil.

[0029] Further, in the direction approaching the oil storage tank from the second weir plate, the depth of the drainage groove gradually decreases.

[0030] As the depth of the drainage groove gradually decreases, it helps to control the flow rate of the oil, enabling it to reach a relatively stable and appropriate speed before entering the oil storage tank, thereby reducing the impact and splashing of the oil flow and maintaining the smoothness of the oil surface in the oil storage tank.

[0031] Further, the longitudinal section of the drainage groove is arc-shaped.

[0032] The arc-shaped drainage groove can naturally guide the oil fraction to flow along its shape, reducing the resistance and turbulence during the flow of the oil fraction, enabling the oil fraction to enter the oil storage tank more smoothly, and avoiding oil fraction splashing or retention caused by poor flow; the arc-shaped drainage groove also helps to reduce the loss of the oil fraction during the flow. Compared with a straight drainage groove, the arc-shaped drainage groove can better constrain the flow direction of the oil flow, preventing the oil fraction from escaping outside the groove due to interference from other factors during the flow, ensuring that more oil fraction can smoothly enter the oil storage tank and improving the recovery rate of the oil fraction.

[0033] Further, an air hole and a pipeline connecting the air hole are provided at the top of the tank body.

[0034] During the oil-water separation and metering process, the fluid flow and temperature change inside the tank may cause changes in the internal air pressure; the air hole and its connected pipeline allow the inside of the tank to communicate with the external atmosphere, thereby effectively balancing the air pressure inside the tank and preventing the tank body from deforming, leaking or being damaged due to too high or too low air pressure.

[0035] Compared with the prior art, the present utility model has the following advantages and beneficial effects:

[0036] By separating adjacent compartments through the above weir plate assembly, the physical isolation of formation fluids during the separation process is ensured. The fluid entering the liquid inlet compartment undergoes sedimentation to separate the oil-water mixture and sand particles. The oil-water mixture flows into the oil-water separation compartment through the first drainage port. According to the principles of immiscibility between water and oil and the mass of water and oil, it stands still and stratifies in the oil-water separation compartment to obtain upper-layer oil and lower-layer water. As the amount of the oil-water mixture discharged from the liquid inlet compartment increases, the liquid level in the oil-water separation compartment gradually rises until it overflows. The overflowing upper-layer oil enters the oil storage compartment through the top wall of the second weir plate, and the lower-layer water enters the water storage compartment through the second drainage port, realizing the separation of water and oil. The integrated treatment process of fluid from entry, separation to final storage simplifies the complex process that requires the cooperation of multiple devices in the traditional process. Flow meters are installed at each key position, which not only achieves accurate measurement of the fluid volume, but more importantly, enables the separation and measurement processes to be carried out synchronously. When the fluid passes through each compartment, its flow rate changes can be recorded in real time, thus ensuring the accuracy of measurement. Since the separation and measurement are carried out synchronously, the errors and time delays that may occur in the traditional method due to step-by-step operations are avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts. In the drawings:

[0038] Figure 1 is a schematic internal structure diagram of the metering tank;

[0039] Figure 2 is a schematic structure diagram of the drainage plate.

[0040] Reference numerals in the drawings and corresponding component names:

[0041] 10, tank body; 20, liquid inlet compartment; 30, oil-water separation compartment; 40, water storage compartment; 50, oil storage compartment; 61, first weir plate; 62, second weir plate; 63, third weir plate; 64, drainage plate; 65, drainage groove; 71, first drainage port; 72, second drainage port; 73, third drainage port; 74, fourth drainage port; 75, liquid inlet; 76, air hole; 81, liquid inlet pipe; 82, pipeline. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] In order to make the purpose, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below in conjunction with the embodiments and the drawings. The illustrative embodiments and descriptions thereof of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0043] Example 1

[0044] Combined with Figure 1 , this Example 1 provides a metering tank for separation and metering, including a tank body 10. An overflow plate assembly is arranged inside the tank body 10, and the chamber of the tank body 10 is divided into a liquid inlet chamber 20, an oil-water separation chamber 30, an oil storage chamber 50 and a water storage chamber 40 through the overflow plate assembly;

[0045] The liquid inlet chamber 20 is provided with a liquid inlet 75, and the liquid inlet 75 is connected with a liquid inlet pipe 81, and the liquid inlet pipe 81 penetrates through the tank body 10; the liquid inlet pipe 81 is used for introducing the fluid to be metered;

[0046] The overflow plate assembly includes a first overflow plate 61, a second overflow plate 62 and a third overflow plate 63;

[0047] The liquid inlet chamber 20 and the oil-water separation chamber 30 are separated by the first overflow plate 61, the oil-water separation chamber 30 and the oil storage chamber 50 are separated by the second overflow plate 62, and the oil-water separation chamber 30 and the water storage chamber 40 are separated by the third overflow plate 63;

[0048] The first overflow plate 61 is provided with a first drain port 71; the liquid inlet chamber 20 and the oil-water separation chamber 30 are communicated through the first drain port 71; the first drain port 71 is used for discharging the oil-water mixture in the liquid inlet chamber 20;

[0049] The third overflow plate 63 is provided with a second drain port 72; the oil-water separation chamber 30 and the water storage chamber 40 are communicated through the second drain port 72; the second drain port 72 is used for discharging the water in the oil-water separation chamber 30;

[0050] The top wall of the second overflow plate 62 is lower than the top wall of the first overflow plate 61;

[0051] The oil storage chamber 50 and the water storage chamber 40 are respectively provided with a third drain port 73 and a fourth drain port 74; the third drain port 73 is used for discharging the oil in the oil storage chamber 50; the fourth drain port 74 is used for discharging the water in the water storage chamber 40;

[0052] Flow meters are arranged at the liquid inlet 75, the first drain port 71, the second drain port 72, the third drain port 73 and the fourth drain port 74. Valves can be arranged at the liquid inlet 75, the first drain port 71, the second drain port 72, the third drain port 73 and the fourth drain port 74. In a communication connection manner, the data collected by the flow meters is transmitted to the control system, and the control system remotely monitors the entire separation and metering process and controls the opening and closing of the valves to achieve flow regulation.

[0053] The adjacent compartments are separated by the above weir plate assembly, ensuring the physical isolation of formation fluids during the separation process. The fluid entering the liquid inlet compartment 20 is subjected to sedimentation to separate the oil-water mixture and sand particles. There is a window on the tank body 10 at the top of the liquid inlet compartment 20, and this window is provided with a cover plate that can be opened and closed. The sand particles in the liquid inlet compartment 20 can be fished out through the window by other instruments; the oil-water mixture flows into the oil-water separation compartment 30 through the first drain port 71. According to the principle that water and oil are immiscible and their different masses, it stands still and stratifies in the oil-water separation compartment 30 to obtain upper-layer oil and lower-layer water; as the amount of the oil-water mixture discharged from the liquid inlet compartment 20 increases, the liquid level in the oil-water separation compartment 30 gradually rises until it overflows. The overflowing upper-layer oil enters the oil storage compartment 50 through the top wall of the second weir plate 62, and the lower-layer water enters the water storage compartment 40 through the second drain port 72, realizing the separation of water and oil; the integrated treatment process of fluid from entry, separation to final storage simplifies the complex process that requires the cooperation of multiple devices in the traditional process; flow meters are set at each key position, not only achieving accurate measurement of the fluid volume, but more importantly, enabling the separation and measurement processes to be carried out synchronously; when the fluid passes through each compartment, its flow rate changes can be recorded in real time, thus ensuring the accuracy of measurement; since the separation and measurement are carried out synchronously, it avoids the errors and time delays that may occur in the traditional method due to step-by-step operations.

[0054] In a specific embodiment, the above first weir plate 61 and second weir plate 62 are vertically arranged in the tank body 10;

[0055] The above first drain port 71 is arranged above the top wall of the second weir plate 62.

[0056] When the oil-water mixture in the above liquid inlet compartment 20 enters the oil-water separation compartment 30 through the first drain port 71, due to gravity and the principle that water and oil are immiscible, the oil and water will start to naturally stratify; and arranging the first drain port 71 above the top wall of the second weir plate 62 can prevent the oil-water mixture from flowing back into the liquid inlet compartment 20 and affecting the separation effect; the flow meters arranged at the first drain port 71 and the second drain port 72 respectively measure the amount of the oil-water mixture entering the oil-water separation compartment 30 and the amount of water entering the water storage compartment 40. The amount of oil in the oil storage compartment 50 can be obtained according to the difference between the amount of the oil-water mixture and the amount of water, synchronously realizing the separation of oil and water and the measurement of the oil volume.

[0057] Embodiment 2

[0058] On the basis of Embodiment 1, the above third weir plate 63 is vertically arranged in the tank body 10;

[0059] The above second drain port 72 is arranged below the top wall of the second weir plate 62.

[0060] When the water in the oil-water mixture is much more than the oil, the upper layer of oil only covers the surface of the water. At this time, since the water after stratification is below the oil-water separation chamber 30, the second drain port 72 is set below the top wall of the second weir plate 62 to ensure that in the oil-water separation chamber 30, after a certain period of residence and stratification, the water can smoothly drain through the second drain port 72 without being interfered by the upper oil layer, which helps to improve the efficiency and purity of water drainage and reduce the residue of the oil-water mixture. The flowmeter set at the second drain port 72 measures the water volume entering the water storage chamber 40 in real time, synchronously realizing oil-water separation and water volume measurement.

[0061] Embodiment 3

[0062] Based on Embodiment 1, the above-mentioned water storage chamber 40 is arranged below the oil-water separation chamber 30;

[0063] The above-mentioned third weir plate 63 is horizontally arranged in the tank body 10.

[0064] When the oil in the oil-water mixture is more than the water or the water-oil content is about the same, when the water in the lower layer gradually decreases in liquid level, it cannot be guaranteed that there must be water at a certain liquid level height. If there is no water at this liquid level height and the second drain port 72 is set at this liquid level height, the oil at this liquid level height will enter the water storage chamber 40, affecting the separation effect. Therefore, the third weir plate 63 is horizontally arranged so that the second drain port 72 is located at the bottom of the oil-water separation chamber 30, reducing the influence of the water content in the oil-water mixture on the separation effect.

[0065] Embodiment 4

[0066] Based on any of the above embodiments, in combination with Figure 2 , the above-mentioned second weir plate 62 is connected with a diversion plate 64;

[0067] The above-mentioned diversion plate 64 inclines from the top wall of the second weir plate 62 towards the oil storage chamber 50.

[0068] The above-mentioned diversion plate 64 enables the oil separated from the oil-water separation chamber 30 to flow more smoothly towards the oil storage chamber 50 along the diversion plate 64, reducing the turbulence and eddy current during the flow of the oil, which helps to maintain the purity and stability of the oil. Due to the existence of the diversion plate 64, the oil will be guided by the diversion plate 64 before entering the oil storage chamber 50 through the second weir plate 62, thus improving the separation efficiency. The diversion plate 64 inclines towards the oil storage chamber 50, which helps to reduce the residue of the oil in other parts of the oil-water separation chamber 30 or the tank body 10, and improves the recovery rate and utilization rate of the oil.

[0069] In a specific embodiment, the upper surface of the above-mentioned diversion plate 64 is concave to form a diversion groove 65; the above-mentioned diversion groove 65 is used to guide the oil on the upper layer of the oil-water separation chamber 30 into the oil storage chamber 50.

[0070] The above drainage groove 65 enables the oil separated from the upper layer of the oil-water separation tank 30 to converge more concentratedly in the groove. Since oil is lighter than water, they will naturally float on the upper layer, and the drainage groove 65 provides a low-resistance path, enabling the oil to flow more easily along the groove wall towards the oil storage tank 50, enhancing the converging ability of the oil and improving the collection efficiency of the oil.

[0071] In a specific embodiment, in the direction approaching the oil storage tank 50 from the second weir plate 62, the groove depth of the drainage groove 65 gradually decreases.

[0072] As the groove depth of the drainage groove 65 gradually decreases, it helps to control the flow rate of the oil, enabling it to reach a relatively stable and appropriate speed before entering the oil storage tank 50, thereby reducing the impact and splashing of the oil flow and maintaining the smoothness of the oil surface in the oil storage tank 50.

[0073] In a specific embodiment, the longitudinal section of the drainage groove 65 is arc-shaped.

[0074] The arc-shaped drainage groove 65 can naturally guide the oil to flow along its shape, reducing the resistance and turbulence of the oil during the flow process, enabling the oil to enter the oil storage tank 50 more smoothly, and avoiding oil splashing or retention caused by poor flow; the arc-shaped drainage groove 65 also helps to reduce the loss of oil during the flow process. Compared with a straight drainage groove 65, the arc-shaped drainage groove 65 can better restrain the flow direction of the oil, preventing the oil from escaping outside the groove due to interference from other factors during the flow process, ensuring that more oil can smoothly enter the oil storage tank 50 and improving the recovery rate of the oil.

[0075] Embodiment 5

[0076] Based on any of the above embodiments, an air hole 76 and a pipeline 82 connecting the air hole 76 are provided at the top of the tank body 10.

[0077] During the processes of oil-water separation and metering, the fluid flow and temperature change inside the tank body 10 may both cause changes in the internal air pressure; the air hole 76 and the pipeline 82 connected thereto allow the inside of the tank body 10 to communicate with the external atmosphere, thereby effectively balancing the air pressure inside the tank and preventing deformation, leakage or damage of the tank body 10 caused by too high or too low air pressure.

[0078] In some cases, the oil-water mixture may contain a certain amount of gas (such as dissolved gas or bubbles), and the presence of these gases may affect the effect of oil-water separation; through the air hole 76 and its pipeline 82, these gases can be discharged outside the tank body 10, thereby promoting the oil-water separation process and improving the separation efficiency and purity; although the air hole 76 is mainly used for balancing air pressure and exhausting gas, its design can also consider preventing excessive volatilization of oil components. For example, a filter screen or an appropriate shielding object can be set at the air hole 76 to block the passage of oil component particles while allowing the gas to flow freely, reducing the loss of oil components and maintaining the purity and quality of the oil components.

[0079] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present utility model. It should be understood that the above description is only the specific embodiments of the present utility model and is not used to limit the protection scope of the present utility model. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included in the protection scope of the present utility model.

Claims

1. A metering tank for separation and metering, characterized in that: The invention comprises a tank body (10), wherein a weir plate assembly is arranged in the tank body (10), and the chamber of the tank body (10) is divided into a liquid inlet bin (20), an oil-water separation bin (30), an oil storage bin (50) and a water storage bin (40) by the weir plate assembly; The liquid inlet bin (20) is provided with a liquid inlet (75), and the liquid inlet (75) is connected to a liquid inlet pipe (81); the liquid inlet pipe (81) is used to introduce the fluid to be measured; The weir plate assembly comprises a first weir plate (61), a second weir plate (62) and a third weir plate (63); The liquid inlet bin (20) and the oil-water separation bin (30) are separated by a first weir plate (61), the oil-water separation bin (30) and the oil storage bin (50) are separated by a second weir plate (62), and the oil-water separation bin (30) and the water storage bin (40) are separated by a third weir plate (63); The first weir plate (61) is provided with a first drain port (71); the liquid inlet tank (20) and the oil-water separation tank (30) are connected via the first drain port (71); the first drain port (71) is used to discharge the oil-water mixture in the liquid inlet tank (20); The third weir plate (63) is provided with a second drain port (72); the oil-water separation chamber (30) and the water storage chamber (40) are connected via the second drain port (72); the second drain port (72) is used to drain water in the oil-water separation chamber (30); The top wall of the second weir plate (62) is lower than the top wall of the first weir plate (61); The oil storage tank (50) and the water storage tank (40) are respectively provided with a third drain port (73) and a fourth drain port (74); the third drain port (73) is used to drain the oil in the oil storage tank (50); the fourth drain port (74) is used to drain the water in the water storage tank (40); The liquid inlet (75), the first drain outlet (71), the second drain outlet (72), the third drain outlet (73) and the fourth drain outlet (74) are all provided with flow meters.

2. The metering tank for separation and metering according to claim 1, characterized in that: The first weir plate (61) and the second weir plate (62) are vertically arranged in the tank body (10); The first drainage port (71) is arranged above the top wall of the second weir plate (62).

3. The metering tank for separation and metering according to claim 2, characterized in that: The third weir plate (63) is vertically arranged in the tank body (10); The second drainage port (72) is arranged below the top wall of the second weir plate (62).

4. The metering tank for separation and metering according to claim 2, characterized in that: The water storage tank (40) is arranged below the oil-water separation tank (30); The third weir plate (63) is arranged transversely in the tank body (10).

5. The metering tank for separation and metering according to claim 1, characterized in that: The second weir plate (62) is connected to a guide plate (64); The guide plate (64) is inclined from the top wall of the second weir plate (62) toward the oil storage tank (50).

6. The metering tank for separation and metering according to claim 5, characterized in that: The upper surface of the guide plate (64) is concave to form a guide groove (65); the guide groove (65) is used to guide the oil in the upper layer of the oil-water separation bin (30) into the oil storage bin (50).

7. The metering tank for separation and metering according to claim 6, characterized in that: In a direction approaching from the second weir plate (62) to the oil storage tank (50), the groove depth of the drainage groove (65) gradually decreases.

8. The metering tank for separation and metering according to claim 6, characterized in that: The longitudinal section of the drainage groove (65) is arc-shaped.

9. The metering tank for separation and metering according to claim 6, characterized in that: The top of the tank body (10) is provided with an air hole (76) and a pipe (82) connected to the air hole (76).

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