An automatic purification device and control method for extracting oil from waste emulsion

Abstract

The present invention belongs to the field of resource treatment of waste emulsion, and particularly relates to an automatic purification device for extracting oil from waste emulsion and a control method thereof. One side of the kettle body is provided with a drain pipe and a liquid inlet pipe which are arranged in sequence from bottom to top, and the other side of the kettle body is provided with an oil drain pipe. An oil drain differential pressure transmitter and a drain differential pressure transmitter are arranged on the kettle body. Among them, the high sampling point of the oil drain differential pressure transmitter is below the horizontal height of the oil drain pipe, and the low sampling point of the drain differential pressure transmitter is above the horizontal height of the drain pipe; the oil drain differential pressure transmitter and the drain differential pressure transmitter are connected to a control system. The automatic purification control method for extracting oil from waste emulsion realized by using the above device can accurately judge whether the liquid is water, oil or a water-oil mixed liquid by using the oil drain differential pressure transmitter and the drain differential pressure transmitter. The present invention continuously and automatically identifies the liquid stratification state at the designed position inside the device kettle body, and can accurately judge whether the position is oil, water or a mixed layer.

Description

Technical Field

[0001] The present invention belongs to the field of resource treatment of waste emulsion, and particularly relates to an automatic purification device and a control method for extracting oil from waste emulsion. Background Art

[0002] The production in modern metallurgy and chemical industries generates a large amount of waste emulsion. Through demulsification separation by a certain process, waste emulsified oil can be extracted from the waste emulsion. Generally, it is regarded as hazardous waste and sent to hazardous waste treatment enterprises for incineration treatment, which not only incurs high treatment costs but also wastes the precious oil in the waste emulsified oil. Some are used as low-grade fuels, and none of these can achieve high-value resource treatment, which is very inconsistent with the needs of the country's circular economy and sustainable development.

[0003] The "Device for Dehydrating and Purifying Waste Emulsified Oil for Aluminum Processing" with the patent number ZL201921799547.7 designs a purification process for extracting oil from waste emulsion, but it cannot achieve automatic operation. Each time for liquid inlet, oil discharge, and water discharge, continuous manual sampling and measurement are required. The temperature control of the device also relies on local thermometers and manual valves for manual adjustment. During operation, a special person is needed to continuously adjust the valves, and the control of the liquid inlet, oil discharge, water discharge, and heating processes is inaccurate, which also causes environmental pollution due to sampling.

[0004] In order to solve the above-mentioned disadvantages existing in the purification process of extracting oil from waste emulsion, following the requirements of the country's circular economy and sustainable development, and achieving the purposes of saving resources, improving the environment, saving human and financial resources, and simplifying operations, an automatic purification device for extracting oil from waste emulsion is thus provided. Summary of the Invention

[0005] The problem solved by the present invention is to overcome the following problems existing in the purification of extracting oil from existing waste emulsion: it is impossible to automatically detect liquids and operate automatically, manual operations are required, and the valve control of the device is inaccurate, which not only wastes a large amount of human and financial resources but also causes environmental pollution and damage. The present invention provides an automatic purification device for extracting oil from waste emulsion. The described automatic purification device for extracting oil from waste emulsion realizes automatic liquid detection and automatic control, and the control of the liquid inlet, oil discharge, water discharge, and heating processes of the device is accurate, saving a large amount of human and financial resources and maintaining the ecological environment.

[0006] To achieve the above object, the present invention adopts the following technical solutions: An automatic purification device for extracting oil from waste emulsion includes a kettle body. On one side of the kettle body, a drain pipe and a liquid inlet pipe are arranged in sequence from bottom to top. On the other side of the kettle body, an oil drain pipe is arranged. An oil drain differential pressure transmitter and a drain differential pressure transmitter are arranged on the kettle body. Among them, the high sampling point of the oil drain differential pressure transmitter is below the horizontal height of the oil drain pipe, and the low sampling point of the drain differential pressure transmitter is above the horizontal height of the drain pipe; the oil drain differential pressure transmitter and the drain differential pressure transmitter are connected to a control system.

[0007] The sampling point of the oil drain differential pressure transmitter is installed below 100 mm of the horizontal height of the oil drain pipe; the sampling point of the drain differential pressure transmitter is installed above 100 mm of the horizontal height of the drain pipe, and the vertical height difference between the two sampling points can at least ensure that the transmitter can accurately measure the pressure difference value.

[0008] A heating device and a pneumatic stirring device are arranged on the kettle body. Among them, the heating device heats the waste emulsion for oil extraction, and the pneumatic stirring device performs pulsating pneumatic stirring on the waste emulsion for oil extraction.

[0009] The heating device is a heat source inlet pipe and a heat source outlet pipe arranged on one side of the kettle body. A heat source inlet pipe valve is arranged between the heat source inlet pipe and the kettle body, and a heat source outlet pipe valve is arranged between the heat source outlet pipe and the kettle body.

[0010] The pneumatic stirring device is a compressed air inlet pipe arranged on one side of the kettle body, and a compressed air inlet pipe valve is arranged between the two.

[0011] A liquid level switch is arranged on the kettle body. The liquid level switch is a high liquid level switch arranged below 100 mm of the highest level of the effective volume of the kettle body and a low liquid level switch arranged above 100 mm of the horizontal height of the oil drain pipe.

[0012] A temperature transmitter is arranged on the side of the kettle body, and the temperature transmitter is connected to the control system.

[0013] An automatic purification control method for extracting oil from waste emulsion using the above device adopts one of the following two methods:

[0014] Method 1:

[0015] The oil drain differential pressure transmitter and the drain differential pressure transmitter respectively obtain the differential pressure data ΔP of the sampling points;

[0016] Calculate the density ρ of the liquid in the kettle body at the high and low position sections of the set differential pressure transmitter sampling point according to the differential pressure data ΔP. ρ = ΔP / gh, where ΔP is the differential pressure between the high and low position sampling points of the differential pressure transmitter, ρ is the density between the high and low position sampling points of the differential pressure transmitter, h is the height difference between the high and low position sampling points of the differential pressure transmitter, and g is the gravitational acceleration value at the measurement site; calculate the liquid density ρ from the ΔP measured by the transmitter device, and compare the measured liquid density ρ with the standard densities of water and oil, so as to accurately judge whether the liquid is water, oil or a water-oil mixed liquid;

[0017] Method 2:

[0018] Derive and set the standard differential pressure ΔP’ of two sampling points using the standard densities of oil and water. ΔP’ = ρ’gh, where ρ’ is the standard density of water or oil, and compare it with the differential pressure data ΔP actually measured by the two transmitters, so as to judge whether the liquid is water, oil or a mixed liquid.

[0019] The automatic purification control method for extracting oil from waste emulsion includes the following processes:

[0020] S1. Set the heating temperature T0, oil discharge differential pressure ΔP10, and water discharge differential pressure ΔP20 for an automatic purification device for extracting oil from waste emulsion through an external PLC or DCS system;

[0021] S2. Transport the waste emulsion for oil extraction to the kettle body through the liquid inlet pipe. The oil discharge differential pressure transmitter and the water discharge differential pressure transmitter detect the density of the liquid according to the differential pressure data, automatically identify the liquid, and accurately judge whether the liquid is oil, water or a mixed liquid;

[0022] S3. Turn on the heating device to heat the mixed liquid in the kettle body. The temperature transmitter measures the temperature of the mixed liquid in the kettle body. When the actual temperature T1 > the set temperature T0, the opening of the heating device decreases until T1 = T0. When the actual temperature T1 < the set temperature T0, the opening of the heating device increases until T1 = T0;

[0023] S4. Turn on the pneumatic stirring device to continuously switch the mixed liquid in the kettle body on and off at high frequency at regular intervals to form pulsating air intake for pneumatic stirring treatment;

[0024] S5. When the actual drainage differential pressure transmitter shows that the actual drainage differential pressure ΔP21 ≥ the drainage differential pressure ΔP20, or when the actual liquid density ρ21 calculated according to the display of the drainage differential pressure transmitter ≥ the density of water ρ20, the drain pipe valve is automatically opened to drain water from the drain pipe until the actual drainage differential pressure ΔP21 = the drainage differential pressure ΔP20, or the actual liquid density ρ21 calculated according to the display of the drainage differential pressure transmitter = the density of water ρ20, then the drain pipe valve is closed; when the actual oil drainage differential pressure transmitter shows that the actual oil drainage differential pressure ΔP11 ≤ the oil drainage differential pressure ΔP10, or when the actual liquid density ρ11 calculated according to the display of the oil drainage differential pressure transmitter ≤ the density of oil ρ20, and the high-level liquid level switch is in the high-level signal, the oil drain pipe valve is automatically opened to drain oil from the oil drain pipe until the liquid level drops to the low-level liquid level switch, and then the oil drain pipe valve is automatically closed.

[0025] The heating temperature T0 set by the control system is 85 - 95 °C.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] Continuously and automatically identify the liquid stratification state at the designed position inside the device kettle body, and can accurately judge whether the position is oil, water or a mixed layer; can stably control the liquid temperature inside the device kettle body, improving the oil-water separation effect; the whole process does not require manual sampling, and will not cause secondary pollution of sampling; realize the full-process automatic control of the liquid inlet, drainage and oil drainage of the device, which can achieve unattended on-site operation and save labor costs; the continuously monitored automatic operation data can provide a solid foundation for the virtualization and intelligentization of digital production in the future. Description of the Drawings

[0028] Figure 1 It is a schematic structural diagram of the present invention.

[0029] Among them, 1 is the kettle body, 2 is the liquid inlet pipe, 3 is the liquid inlet pipe valve, 4 is the drain pipe, 5 is the drain pipe valve, 6 is the oil drain pipe, 7 is the oil drain pipe valve, 8 is the compressed air inlet pipe, 9 is the compressed air inlet pipe valve, 10 is the heat source inlet pipe, 11 is the heat source inlet pipe valve, 12 is the heat source outlet pipe, 13 is the heat source outlet pipe valve, 14 is the exhaust pipe, 15 is the oil drainage differential pressure transmitter, 16 is the drainage differential pressure transmitter, 17 is the temperature transmitter, 18 is the high-level liquid level switch, and 19 is the low-level liquid level switch. Detailed Embodiments

[0030] To make the objectives, technical solutions and advantages of the present invention more clear, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention application, for those skilled in the art, several changes and improvements made, and all other embodiments obtained, fall within the scope of protection of the present invention.

[0031] As Figure 1 shown, an automatic purification device for extracting oil from waste emulsion includes: a kettle body 1, a liquid inlet pipe 2, a liquid inlet pipe valve 3, a drain pipe 4, a drain pipe valve 5, an oil drain pipe 6, an oil drain pipe valve 7, a compressed air inlet pipe 8, a compressed air inlet pipe valve 9, a heat source inlet pipe 10, a heat source inlet pipe valve 11, a heat source outlet pipe 12, a heat source outlet pipe valve 13, an exhaust pipe 14, an oil drain differential pressure transmitter 15, a drain differential pressure transmitter 16, a temperature transmitter 17, a high-level liquid level switch 18, and a low-level liquid level switch 19. An automatic purification device for extracting oil from waste emulsion includes a kettle body 1. An exhaust pipe 14 is provided at the top of the kettle body 1. A transmitter device and a liquid level switch are provided on the kettle body 1. The transmitter device detects and measures the temperature and differential pressure of the waste emulsion. A drain pipe 4 and a liquid inlet pipe 2 are respectively provided on one side of the kettle body 1 from bottom to top. A heating device, a pneumatic stirring device, and an oil drain pipe 6 are provided on the other side of the kettle body 1 from bottom to top. The heating device heats the waste emulsion for oil extraction, and the pneumatic stirring device performs pulsating pneumatic stirring on the waste emulsion for oil extraction.

[0032] The heating device is a heat source inlet pipe 10 and a heat source outlet pipe 12 provided on one side of the kettle body 1. A heat source inlet pipe valve 11 is provided between the heat source inlet pipe 10 and the kettle body 1, and a heat source outlet pipe valve 13 is provided between the heat source outlet pipe 12 and the kettle body 1. The heating device heats the waste emulsion for oil extraction inside the kettle body 1 to separate the waste emulsion for oil extraction into water and oil.

[0033] The pneumatic stirring device is a compressed air inlet pipe 8 provided on one side of the kettle body 1, and a compressed air inlet pipe valve 9 is provided between them. The pneumatic stirring device performs pulsating pneumatic stirring on the waste emulsion for oil extraction inside the kettle body 1 to promote the separation of the waste emulsion for oil extraction into water and oil.

[0034] The transmitter device includes an oil discharge differential pressure transmitter 15, a water discharge differential pressure transmitter 16 provided on the main body of the kettle body 1, and a temperature transmitter 17 provided on the side of the kettle body 1. Both the oil discharge differential pressure transmitter 15 and the water discharge differential pressure transmitter 16 adopt high-precision transmitters, which can measure the differential pressure below 1 kPa. The vertical height difference of the sampling point positions of the transmitters is more than 50 mm, or at least it can ensure that the transmitter can accurately measure the differential pressure value. The oil discharge differential pressure transmitter 15 is installed below 100 mm of the horizontal height of the oil discharge pipe 6, and it is ensured that the high-level sampling point of the oil discharge differential pressure transmitter is below the horizontal height of the oil discharge pipe 6; the water discharge differential pressure transmitter 16 is installed above 100 mm of the horizontal height of the drain pipe 4, and it is ensured that the low-level sampling point of the water discharge differential pressure transmitter 16 is above the horizontal height of the drain pipe 4. The device uses the oil discharge differential pressure transmitter 15 and the water discharge differential pressure transmitter 16 to respectively obtain the differential pressure data ΔP of the sampling points; according to the differential pressure data ΔP, the density ρ of the liquid in the kettle body between the set high and low positions of the differential pressure transmitter sampling points is calculated, ρ = ΔP / gh, and ΔP = ρgh is deduced. Where ΔP is the differential pressure between the high and low sampling points of the differential pressure transmitter, ρ is the density between the high and low sampling points of the differential pressure transmitter, h is the height difference between the high and low sampling points of the differential pressure transmitter, and g is the gravitational acceleration value at the measurement site. The liquid density is calculated from the ΔP measured by the transmitter device, and the measured liquid density ρ is compared with the standard densities of water and oil, so as to accurately judge whether the liquid is water, oil or a mixed liquid. Using the standard densities of oil and water, the standard differential pressure ΔP’ of the two sampling points is deduced and set, ΔP’ = ρ’gh, where ρ’ is the standard density of water or oil, and it is compared with the differential pressure data ΔP actually measured by the two transmitters, so as to judge whether the liquid is water, oil or a mixed liquid.

[0035] The liquid level switches are a high liquid level switch 18 and a low liquid level switch 19. The high liquid level switch 18 is set below 100 mm of the highest position of the effective volume of the kettle body 1; the low liquid level switch 19 is set above 100 mm of the horizontal height of the oil discharge pipe 6. The high liquid level switch 18 and the low liquid level switch 19 can send out high-level signals and low-level signals when the liquid level in the device kettle body 1 reaches the high liquid level switch 18 and the low liquid level switch 19.

[0036] An automatic purification device for extracting oil from waste emulsion uses the differential pressure data of the oil discharge differential pressure transmitter 15 and the water discharge differential pressure transmitter 16 to calculate the density of the liquid in the kettle body 1 at the set height difference position section, indirectly reflecting whether the liquid at this position section is water, oil or a mixed liquid, and the transmitter device transmits data signals to the control system. The control system can be an external PLC or DCS system. The external PLC or DCS system performs interlocking switch control on the inlet pipe valve 3, the drain pipe valve 5, the oil discharge valve 7, the heat source inlet pipe valve 11, and the heat source outlet pipe valve 13 according to the set control program, and automatically controls the whole process of heating, liquid inlet, drainage, and oil discharge.

[0037] For the kettle body 1 of the automatic purification device for extracting oil from waste emulsion, the patent number ZL201921799547.7 "An aluminum processing waste emulsion oil dehydration and purification device" is adopted, and the valves are automatic valves.

[0038] The working process and set control program of a control method for an automatic purification device for extracting oil from waste emulsion are as follows:

[0039] Set the heating temperature T0, the oil discharge differential pressure ΔP10, and the water discharge differential pressure ΔP20 for an automatic purification device for extracting oil from waste emulsion through an external PLC or DCS system, or set the heating temperature T0, the density of oil ρ10, and the density of water ρ20. Among them, the set heating temperature T0 of the device is 85 - 95 °C, which is set through an external PLC or DCS system. The oil discharge differential pressure ΔP10 is calculated according to the formula ΔP = ρgh derived from the density conversion formula ρ = ΔP / gh, and then according to the density of oil ρ10; the water discharge differential pressure ΔP20 is calculated according to the formula ΔP = ρgh derived from the density conversion formula ρ = ΔP / gh, and then according to the density of water ρ20. Among them, the density of oil ρ10 is the density of the purified oil, and the density of water ρ20 is the set drainage density based on the actual measurement results.

[0040] Open the valve 3 of the liquid inlet pipe, and the waste emulsion oil is transported from the liquid inlet pipe 2 into the kettle body 1. When the liquid level in the kettle body 1 reaches the horizontal height of the sampling point of the high-level liquid level switch 18, the high-level liquid level switch 18 sends a high-level signal, and the valve 3 of the liquid inlet pipe is closed to stop transporting the waste emulsion into the kettle body 1, preventing the excessive transportation of the waste emulsion oil from overflowing from the exhaust pipe 14 at the top of the kettle body 1. After stopping the transportation of the waste emulsion oil into the kettle body 1, the oil discharge differential pressure transmitter 15 and the water discharge differential pressure transmitter 16 in the transmitter device detect the waste emulsion inside the kettle body 1, and then calculate according to the information collected by the oil discharge differential pressure transmitter 15 and the water discharge differential pressure transmitter 16 to judge whether the liquid inside the kettle body 1 is water, oil, or a mixed liquid in a certain height area. The transmitter device uses the differential pressure data of the oil discharge differential pressure transmitter 15 and the water discharge differential pressure transmitter 16 to calculate the density of the liquid inside the kettle body 1 in the set high and low differential pressure position section. It is derived from the density conversion formula ρ = ΔP / gh to ΔP = ρ / gh, and the density of the liquid is calculated from the measured ΔP and compared with the density of water and oil, so as to judge whether the liquid between the high and low sampling points of the differential pressure transmitter is water, oil, or a mixed liquid. Among them, in the density conversion formula, ΔP is the differential pressure between the high and low sampling points of the differential pressure transmitter, ρ is the density between the high and low sampling points of the differential pressure transmitter, h is the height difference between the high and low sampling points of the differential pressure transmitter, and g is the gravitational acceleration value at the measurement site.

[0041] After the kettle body 1 is filled with liquid, open the valve 11 of the heat source inlet pipe and the valve 13 of the heat source outlet pipe, and start heating the mixed liquid in the kettle body 1 to separate the oil and water in the mixed liquid, separating water and oil. After the liquid separation, let it stand for a certain period of time. When the drain differential pressure transmitter 16 determines that the liquid at this height is water, open the drain pipe valve 5 to drain the water in the kettle body 1 from the drain pipe 4. When the oil drain differential pressure transmitter 15 determines that the liquid at this height is oil and is not at the low liquid level, open the oil drain pipe valve to drain the oil in the kettle body 1 from the oil drain pipe 6.

[0042] When the actual temperature T1 of the liquid in the kettle body 1 > the set temperature T0, reduce the opening degree of the heat source inlet valve 11, and the reduction range of the opening degree of the heat source inlet valve 11 is 5 - 10%. After setting 1 - 2h as required, when the mixed liquid in the kettle body 1 still maintains the actual temperature T1 > the set temperature T0, further reduce the opening degree of the heat source inlet valve 11, and the reduction range is 5 - 10%, and so on until T1 = T0. When the actual temperature T1 of the mixed liquid in the kettle body 1 < the set temperature T0, increase the opening degree of the heat source inlet valve 11, and the increase range of the opening degree of the heat source inlet valve 11 is 5 - 10%. After setting 1 - 2h as required, when the mixed liquid in the kettle body 1 still maintains the actual temperature T1 < the set temperature T0, further increase the opening degree of the heat source inlet valve 11, and the increase range is 5 - 10%, and so on until T1 = T0.

[0043] Start the pneumatic stirring device to perform high-frequency pulsating pneumatic stirring on the mixed liquid in the kettle body 1 to promote the oil-water separation of the mixed liquid. The valve 9 of the compressed air inlet pipe is continuously switched several times at regular intervals to form short-term pulsed air intake. The switching time interval of the valve 9 of the compressed air inlet pipe is 1 - 8h each time, and the opening time each time is about 5 - 20s.

[0044] When the drain differential pressure transmitter 16 shows that the actual drain differential pressure ΔP21 ≥ the drain differential pressure ΔP20, that is, when the drain differential pressure transmitter 16 shows that the calculated actual liquid density ρ21 ≥ the density of water ρ20. Open the drain pipe valve 5 to drain the water separated from the oil and water in the kettle body 1 from the drain pipe 4 until the actual drain differential pressure ΔP21 = the drain differential pressure ΔP20, or according to the calculation of the drain differential pressure transmitter 16, the actual liquid density ρ21 = the density of water ρ20, then close the drain pipe valve 5 to stop the liquid from draining from the drain pipe 4. And, in order to ensure that the liquid in an automatic purification device for extracting oil from waste emulsion can be statically separated for as long as possible, the interval time between two adjacent drainings is generally set to 4 - 8h.

[0045] When the oil drainage differential pressure transmitter 15 shows that the actual oil drainage differential pressure ΔP11 ≤ the oil drainage differential pressure ΔP10, that is, according to the calculation based on the display of the oil drainage differential pressure transmitter 15, the actual liquid density ρ11 ≤ the density of the oil ρ20, and when the low-level liquid level switch 19 is not in the low-level signal state, the oil drainage pipe valve 7 is opened until the liquid level drops to the low-level alarm position of the low-level liquid level switch 19, and then the oil drainage pipe valve 7 is closed.

[0046] The automatic purification device for extracting oil from waste emulsion of the present invention continuously and automatically identifies the liquid at the designed position in the device kettle body 1, and can accurately judge whether the position is oil, water or a mixed layer; it can stably control the liquid temperature in the kettle body 1 of the automatic purification device for extracting oil from waste emulsion, improving the oil-water separation effect; the whole process does not require manual sampling, and will not cause secondary pollution of sampling; it realizes the full-process automatic control of the liquid inlet, drainage and oil drainage of the device, can achieve unattended operation on site, and save labor costs; the continuously monitored automatic operation data can provide a solid foundation for the subsequent realization of the virtualization and intelligence of digital production.

[0047] As described above for the present invention, it is only the preferred embodiment shown in combination with the drawings of the present invention application, but not used to limit the protection scope of the present invention application. It should be noted that for those skilled in the art, without departing from the overall concept of the present invention, any modifications, equivalent substitutions, improvements, etc. made by those skilled in the art without creative labor should be included in the protection scope of the present invention application.

Claims

1. An automatic purification device for extracting oil from waste emulsion, comprising a kettle body (1), characterized in that: On one side of the kettle body (1), there is a drain pipe (4) and a liquid inlet pipe (2) arranged successively from bottom to top. On the other side of the kettle body (1), there is an oil drain pipe (6). An oil drain differential pressure transmitter (15) and a water drain differential pressure transmitter (16) are arranged on the kettle body (1). Among them, the high sampling point of the oil drain differential pressure transmitter (15) is below the horizontal height of the oil drain pipe (6), and the low sampling point of the water drain differential pressure transmitter (16) is above the horizontal height of the drain pipe (4); the oil drain differential pressure transmitter (15) and the water drain differential pressure transmitter (16) are connected to the control system; a liquid level switch is arranged on the kettle body (1). The liquid level switch is a high liquid level switch (18) arranged below 100 mm at the highest position of the effective volume of the kettle body (1) and a low liquid level switch (19) arranged above 100 mm at the horizontal height of the oil drain pipe (6); a temperature transmitter (17) is arranged on the side of the kettle body (1), and the temperature transmitter (17) is connected to the control system; The automatic purification control method for extracting oil from waste emulsion using the above device includes the following processes: S1. Set the heating temperature T0, oil drain differential pressure ΔP10, and water drain differential pressure ΔP20 for an automatic purification device for extracting oil from waste emulsion through an external PLC or DCS system; S2. Transport the waste emulsion for oil extraction to the kettle body (1) through the liquid inlet pipe (2). The oil drain differential pressure transmitter (15) and the water drain differential pressure transmitter (16) detect the density of the liquid according to the differential pressure data, use the density conversion formula to automatically identify the liquid, and accurately judge whether the liquid is oil, water, or a mixed liquid; S3. Turn on the heating device to heat the mixed liquid in the kettle body (1). The temperature transmitter (17) measures the temperature of the mixed liquid in the kettle body (1). When the actual temperature T1 > the set temperature T0, the opening of the heating device decreases until T1 = T0. When the actual temperature T1 < the set temperature T0, the opening of the heating device increases until T1 = T0; S4. Turn on the pneumatic stirring device to continuously switch the mixed liquid in the kettle body (1) on and off at high frequency at regular intervals to form pulsating air intake for pneumatic stirring treatment; S5. When the water drain differential pressure transmitter (16) shows that the actual water drain differential pressure ΔP21 ≥ the water drain differential pressure ΔP20 or calculates that the actual liquid density ρ21 ≥ the density of water ρ20 according to the display of the water drain differential pressure transmitter, automatically open the drain pipe valve (5) to drain the water from the drain pipe (4) until the actual water drain differential pressure ΔP21 = the water drain differential pressure ΔP20 or calculates that the actual liquid density ρ21 = the density of water ρ20 according to the display of the water drain differential pressure transmitter, and then close the drain pipe valve (5); when the oil drain differential pressure transmitter (15) shows that the actual oil drain differential pressure ΔP11 ≤ the oil drain differential pressure ΔP10 or calculates that the actual liquid density ρ11 ≤ the density of oil ρ20 according to the display of the oil drain differential pressure transmitter, and the high liquid level switch (18) is in the high-level signal, automatically open the oil drain pipe valve (7) to drain the oil from the oil drain pipe (6) until the liquid level drops to the low liquid level switch (19), and then automatically close the oil drain pipe valve (7).

2. The automatic purification device for extracting oil from waste emulsion according to claim 1, characterized in that: The sampling point of the oil drainage differential pressure transmitter (15) is installed below 100 mm of the horizontal height of the oil drainage pipe (6); the sampling point of the drainage differential pressure transmitter (16) is installed above 100 mm of the horizontal height of the drainage pipe (4), and the vertical height difference between the two sampling points can at least ensure that the transmitter can accurately measure the pressure difference value.

3. The automatic purification device for extracting oil from waste emulsion according to claim 1, characterized in that: A heating device and a pneumatic stirring device are arranged on the kettle body (1). Among them, the heating device heats the oil extracted from the waste emulsion, and the pneumatic stirring device performs pulsating pneumatic stirring on the oil extracted from the waste emulsion.

4. An automated purification device for extracting oil from waste emulsion according to claim 3, characterized in that: The heating device is a heat source inlet pipe (10) and a heat source outlet pipe (12) arranged on one side of the kettle body (1). A heat source inlet pipe valve (11) is arranged between the heat source inlet pipe (10) and the kettle body (1), and a heat source outlet pipe valve (13) is arranged between the heat source outlet pipe (12) and the kettle body (1).

5. The automated purification device for extracting oil from waste emulsion according to claim 3, characterized in that: The pneumatic stirring device is a compressed air inlet pipe (8) arranged on one side of the kettle body (1), and a compressed air inlet pipe valve (9) is arranged between the two.

6. An automatic purification device for extracting oil from waste emulsion according to claim 1, characterized in that: The heating temperature T0 set by the control system is 85 - 95 °C.

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