Intelligent multi-stage counter-current water washing control device and control method thereof

Abstract

This invention relates to an intelligent multi-stage countercurrent water washing control device and its control method, which solves the technical problems of low washing efficiency and easy emulsification in existing water washing devices. It comprises two or more water washing units, each with a housing. The top of the housing has a water inlet and an oil outlet. The water inlet includes a water inlet and a flow meter, while the bottom of the housing has an annular liquid distributor and a water outlet. The annular liquid distributor is connected to the oil inlet, and a baffle structure for stabilizing water flow is provided around it. The water outlet of the upper water washing unit is connected to the water inlet of the lower water washing unit, and the oil outlet of the lower water washing unit is connected to the oil inlet of the upper water washing unit. The oil outlet is connected to a storage tank via an oil inlet pipe, and the storage tank is connected to the oil inlet of the upper water washing unit via an oil outlet pipe. A pump is installed on the oil outlet pipe. The water washing unit also includes a PLC feedback system, comprising a PLC, sensors for sensing the liquid state within the water washing unit, and regulating valves for controlling liquid flow. This invention can be widely applied in the field of chemical water washing.

Description

Technical Field

[0001] This invention relates to the field of fine chemicals, and in particular to an intelligent multi-stage countercurrent water washing control device and its control method. Background Technology

[0002] In the field of fine chemicals, neutralization and washing processes are typically required to remove excess acids, alkalis, or salts from oil-phase products. Traditionally, the neutralization and washing processes rely on manual control or simple mechanical stirring devices, which presents numerous problems.

[0003] For example, traditional washing equipment often uses a single-stage or fixed-stage series structure, which makes it difficult to flexibly adjust the number and sequence of washing stages according to the material properties and process requirements, resulting in low washing efficiency and difficulty in accurately controlling the amount of solvent residue.

[0004] Meanwhile, the existing equipment mostly uses unidirectional stirring, which can easily lead to uneven mixing of materials and even emulsification, affecting mass transfer and subsequent separation processes.

[0005] In addition, in the traditional washing process, the material conveying and flow control between each washing unit mainly rely on manual experience, resulting in a low degree of automation. This not only increases the labor intensity of operators but also makes it difficult to ensure the stability of the washing process, thus affecting the uniformity of product quality.

[0006] Furthermore, traditional neutralization washing is an intermittent process with insufficient continuity of procedures, which restricts production efficiency; multiple washing cycles also lead to water waste.

[0007] To address the above-mentioned problems, this invention proposes an intelligent multi-stage reversible washing device and its control method. Summary of the Invention

[0008] To address the technical problems of low washing efficiency and easy emulsification in existing washing devices, this invention provides an intelligent multi-stage countercurrent washing control device and its control method.

[0009] This invention provides an intelligent multi-stage countercurrent water washing control device, which includes a storage tank and an oil inlet. The device is characterized by having two or more sets of water washing units stacked on top of each other. Each water washing unit has a housing, with a water inlet and an oil outlet at the top. The water inlet has a water inlet and a flow meter, and the bottom of the housing has an annular liquid distributor and a water outlet. The annular liquid distributor is connected to the oil inlet, and a baffle structure for stabilizing water flow is provided around it. The water outlet of the upper water washing unit is connected to the water inlet of the lower water washing unit, and the oil outlet of the lower water washing unit is connected to the oil inlet of the upper water washing unit. The oil outlet is connected to the storage tank via an oil inlet pipe, and the storage tank is connected to the oil inlet of the upper water washing unit via an oil outlet pipe. A pump is installed on the oil outlet pipe. The water washing unit also includes a PLC feedback system, which includes a PLC, a sensor for sensing the liquid state within the water washing unit, and a regulating valve for controlling the liquid flow. The PLC is electrically connected to the sensor and the regulating valve.

[0010] Preferably, the sensors include an interface meter and a flow meter located inside the washing unit housing, a salinity meter located at the outlet of the washing unit, and a pH meter and a salinity meter located inside the storage tank.

[0011] Preferably, the water inlet device is further provided with an inlet, and an inlet regulating valve is provided between the water inlet device and the inlet, the inlet regulating valve being electrically connected to the PLC.

[0012] Preferably, the oil inlet of the bottom water washing unit is also equipped with a pH meter and a salinity meter.

[0013] The present invention also provides a control method for an intelligent multi-stage countercurrent water washing control device, which employs the intelligent multi-stage countercurrent water washing control device described above, and includes the following steps: Step 1: After the aqueous phase enters the upper water washing unit, it is mixed and washed with the oil phase discharged from the middle water washing unit. The PLC acquires the oil phase data discharged from the middle water washing unit and uses an interface meter, regulating valve and flow meter to stably control the oil-water interface. The salinity and pH value of the upper water washing unit storage tank are monitored in real time by the pH meter and salinity meter of the storage tank to control the flow rate and concentration of the additive liquid and ensure that the oil phase is within the process value range. Step 2: After being washed by the upper water washing unit, the aqueous phase enters the middle water washing unit, where it is mixed and washed again with the oil phase discharged from the lower water washing unit. The PLC acquires the oil phase data discharged from the lower water washing unit and uses an interface meter, regulating valve, and flow meter to stably control the oil-water interface. The salinity and pH value of the middle water washing unit storage tank are monitored in real time by the pH meter and salinity meter in the storage tank to control the flow rate and concentration of the additive solution, and to provide a dynamic calibration basis for the aqueous phase flow rate and alkali concentration in Step 1. Step 3: After being washed by the middle layer water washing unit, the aqueous phase enters the lower layer water washing unit, where it is mixed and washed with the oil phase discharged from the lower layer water washing unit. The PLC uses an interface meter, regulating valve, and flow meter to stably control the oil-water interface. The salinity and pH value of the lower layer water washing unit storage tank are monitored in real time by the pH meter and salinity meter in the storage tank, which controls the flow rate and concentration of the additive solution and provides a dynamic calibration basis for the aqueous phase flow rate and alkali concentration in Step 2. Step 4: Discharge the aqueous phase after three-stage water washing and obtain the oil phase after three-stage water washing in Step 1.

[0014] Preferably, the opening of the regulating valve is adjusted in increments of 10%. If the expected effect is not achieved after deviating from the target range, the adjustment is continued in increments of 10%. If the adjustment is too large or too small, the opening is adjusted back by 5%, and so on, until the interface stabilizes within the set range.

[0015] Preferably, when there is a coupling conflict between the water phase flow rate regulation of the preceding step and the following step, priority should be given to ensuring the desalination effect of the oil phase in the preceding step, while also taking into account the water phase load balance in the following step.

[0016] Preferably, in step one, the salinity and pH value of the storage tank are the priority control targets. The PLC dynamically adjusts the water phase flow rate and alkali dosage of the next stage of water washing based on the feedback values ​​from the salinity meter and pH meter in the storage tank.

[0017] The beneficial effects of this invention are: 1. Compared to traditional water washing devices, this invention achieves continuous operation of neutralization water washing. Compared to the traditional intermittent neutralization water washing operation—mixing, settling, sedimentation, stratification, and separation—the processing cycle is shortened from 200 minutes to 120 minutes. This reduces the need for one person to manually observe water discharge and improves the stability of the water washing process.

[0018] 2. The present invention effectively avoids the problems of increased emulsification, blurred interface and inability to settle and separate into layers caused by excessive stirring or excessive flow rate in traditional water washing kettles, through the countercurrent contact formed by the water phase flowing from top to bottom under the action of gravity and the oil phase flowing from bottom to top under the action of buoyancy.

[0019] 3. Compared to traditional single-stage washing, this invention uses a three-stage gradient washing process, which not only has a stronger processing capacity and a smaller footprint, but also facilitates integrated design, further reducing the overall footprint of the device. With the same capacity of 30 cubic meters, this device achieves integrated continuous operation of neutralization and washing, reducing the overall equipment volume by approximately 40% compared to a scheme where two separate neutralization and washing devices are connected in series.

[0020] 4. Compared with the series operation of three single-stage water washing, the three-stage gradient continuous water washing design of this device results in a higher salt content in the final effluent phase and a reduction of approximately 50% in the salt content of the oil phase water, while maintaining the same water consumption. This leads to greater water conservation for the same processing capacity.

[0021] 5. The device's PLC-integrated closed-loop feedback system design enables the device to continuously provide feedback and automatically adjust to the optimal operating conditions, reducing manual input.

[0022] 6. The addition of interface design enables the device to dynamically adapt to various materials and working conditions, supports seamless switching between multiple products, and has a wider range of applicability.

[0023] 7. The distribution ports of the annular distributor are arranged in a ring array, and the aperture and angle of each port are precisely designed to ensure that the oil phase is uniformly dispersed in the aqueous phase and forms a stable countercurrent interface. Compared with traditional stirring and mixing methods, this design significantly reduces the risk of emulsification and effectively improves mass transfer efficiency.

[0024] 8. In traditional extraction towers, backmixing and channeling easily occur during countercurrent contact between the oil and water phases, leading to instability at the two-phase interface and uneven mass transfer. This invention achieves stable countercurrent separation even when the density difference between the oil and water phases is small through the coordinated control of annular liquid distribution and baffles, combined with pump assistance.

[0025] 9. The washing units at each stage of this device adopt a modular design, which can flexibly increase or decrease the number of washing stages according to the material characteristics and process requirements to adapt to the desalination accuracy requirements of different products.

[0026] 10. The water phase outlet and the oil phase outlet are arranged diagonally with the water phase outlet offset vertically. The semi-circular baffle guides the fluid flow to ensure that there is no short circuit or stagnation in the two-phase fluid during the separation process, thereby maximizing the mass transfer efficiency. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the water phase transfer section of the present invention; Figure 2 This is a schematic diagram of the oil phase transfer section of the present invention; Figure 3 This is a schematic diagram of the layout of the ring-shaped liquid distributor of the present invention; Figure 4 This is a top view schematic diagram of the aqueous phase path of the present invention.

[0029] Explanation of symbols in the attached drawings: 100. First-stage water washing unit; 101. First-stage water washing unit housing; 102. First-stage first baffle; 103. First-stage second baffle; 104. First-stage ring-type liquid distributor; 105. External discharge port; 1051. Seventh salinity meter; 1052. Seventh regulating valve; 106. Drain port; 107. First oil inlet; 108. Second salinity meter; 109. First interface meter; 1010. First pH meter; 1011. Third salinity meter; 110. Third-stage water inlet device; 111. Third flow pipe; 112. Third addition port; 113. Fifth regulating valve; 114. Sixth regulating valve; 115. Third flow meter; 121. Second oil inlet; 122. First oil inlet pipe; 123. First storage tank; 124. First-stage pump; 125. First oil outlet pipe; 126. Second pH meter; 127. Fourth salinity meter; 200. Second-stage water washing unit; 201. Second-stage water washing unit housing; 202. Second-stage first baffle; 203. Second-stage second baffle; 204. Second-stage ring-type liquid distributor; 205. Second water outlet; 207. Second interface meter; 208. First salinity meter; 210. Second-stage water inlet device; 211. Second flow pipe; 212. Second inlet; 213. Third regulating valve; 214. Fourth regulating valve; 215. Second flow meter; 221. Third oil inlet; 222. Second oil inlet pipe; 223. Second storage tank; 224. Second-stage pump; 225. Second oil outlet pipe; 226. Third pH meter; 227. Fifth salinity meter; 300. Third-stage water washing unit; 301. Third-stage water washing unit housing; 302. Third-stage first baffle; 303. Third-stage second baffle; 304. Third-stage ring-type liquid distributor; 305. First water outlet; 306. Water inlet; 307. Third interface meter; 310. First-stage water inlet device; 311. First liquid pipe; 312. First addition port; 313. First regulating valve; 314. Second regulating valve; 315. First flow meter; 321. Fourth oil inlet; 322. Third oil inlet pipe; 323. Third storage tank; 324. Third-stage pump; 325. Third oil outlet pipe; 326. Fourth pH meter; 327. Sixth salinity meter; 3041. Ring-type liquid distributor inlet; 3042. Liquid distribution channel; 3043. Liquid distribution port. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments, so that those skilled in the art can easily implement the present invention.

[0032] Example 1: As Figure 1-2As shown, this invention includes a first-stage water washing unit 100, a second-stage water washing unit 200, and a third-stage water washing unit 300. The water washing units are connected in series via overflow pipes to ensure stable unidirectional water flow. Each water washing zone has a regulating valve at its bottom for easy control of the liquid level and washing time. The water washing units are rigidly connected using stainless steel flanges, with mirror-polished sealing surfaces and embedded fluororubber O-rings to ensure zero leakage under 1.6MPa operating conditions. Each water washing unit is divided into a top-down water phase transfer section and a bottom-up oil phase transfer section. The number of water washing stages can be adjusted by flexibly adding or removing water washing zone modules according to process requirements.

[0033] The first-stage washing unit 100 uses a 20mm thick stainless steel base plate and an 18mm thick stainless steel side plate. The second-stage washing unit 200 uses 18mm thick stainless steel for both its base plate and side walls. The third-stage washing unit 300 also uses 18mm thick stainless steel for both its base plate and side walls. The three washing units are stacked cylindrical structures with heights of 2.4m, 3.1m, and 3.8m respectively, and a uniform diameter of 2.0m. Therefore, the volumes of the three washing units are 7.54m³, 9.74m³, and 11.94m³ respectively, for a total effective volume of 39.22m³.

[0034] This invention integrates a PLC system to achieve fully automated control of the entire process, ensuring real-time monitoring and dynamic adjustment of parameters at each stage, significantly reducing the frequency of manual intervention. Its core lies in the decoupling design of the aqueous and oil phase transfer paths, making them both independent and collaborative in physical space and control logic: the aqueous phase path focuses on multi-stage recovery, while the oil phase path focuses on efficient purification. Through precise gradient flow rate matching, efficient mass transfer at the interface between the two phases is ensured without emulsification. The core of the entire control logic is based on real-time feedback of the salt content and turbidity of the oil phase at each stage, dynamically adjusting the injection rate and pH compensation of the aqueous phase at each stage. Simultaneously, the priority of aqueous phase control is highest at stage three, followed by stage two, and lastly stage one—this is because the stage three water washing unit (300 units) is the largest in scale and has the strongest adaptability.

[0035] The third-stage washing unit 300, with its maximum volume and optimal control weight, undertakes the final salt removal and precise interface stabilization tasks; the second-stage washing unit 200, as the connecting hub, takes into account both impurity redispersion and pH buffering functions; and the first-stage washing unit 100 focuses on coarse washing and pre-sedimentation, effectively relieving the processing pressure of subsequent units.

[0036] like Figure 1The diagram shows a schematic of the water phase transfer section of this invention. Clean water enters from the top inlet 306, flows downwards along the primary water inlet device 310 into the housing 301 of the third-stage washing unit, and then exits through the bottom first outlet 305. The primary water inlet device 310 is equipped with a first flow pipe 311 and a first addition port 312. The first flow pipe 311 is a metal pipe, using a 316L stainless steel corrugated pipe structure with an inner diameter of 80mm, and incorporates spiral guide vanes to suppress turbulence. The spiral guide vanes are blade structures installed within the fluid channel, arranged in a spiral pattern. Their main function is to guide the fluid along a specific path, transforming straight water flow into spiral flow. The water flows slowly down the spiral path, significantly reducing the terminal velocity and impact energy. The lower end of the first flow pipe 311 is open, and the upper end is connected to the inlet 306 and the first addition port 312 via regulating valves. The flow rate of the aqueous phase flowing through the first flow pipe 311 via the inlet 306 can be monitored by the first flow meter 315, and the flow rate can be controlled by the first regulating valve 313. The properties of the aqueous phase can be adjusted according to the properties of the oil phase during water washing, such as controlling the pH value of the aqueous phase or specifically removing certain salts. The second regulating valve 314 is used to regulate the flow rate of the additive in the first addition port 312. By adjusting the flow rates of the aqueous phase and the additive, the concentration of the additive in the aqueous phase is controlled, thereby achieving the neutralization or water washing operation of the oil phase.

[0037] like Figure 4 As shown, during the washing process in the third-stage washing unit 300, the aqueous phase flowing out from the first flow pipe 311 is blocked by the first baffle 302 and the second baffle 303, and flows towards the first outlet 305 at the opposite corner. The oil phase, after flowing out from the third-stage annular distributor 304, floats to the surface of the third-stage washing liquid. During the floating process, constrained by the baffles, the oil phase does not disperse and float, and simultaneously makes full contact with the aqueous phase for mass transfer, thereby achieving the effect of neutralization washing.

[0038] The second-stage washing unit 200 is structurally similar to the third-stage washing unit 300. The aqueous phase flows uniformly from the first outlet 305 through the secondary inlet device 210 into the housing 201 of the second-stage washing unit. The secondary inlet device 210 is equipped with a second flow pipe 211 and a second inlet 212. The second flow pipe 211 is connected to the second inlet 212 and the first outlet 305 via a fourth regulating valve 214 and a third regulating valve 213, respectively. The second inlet 212 can be used to inject buffers or complexing agents, and the addition rate is controlled by the fourth regulating valve 214 to dynamically adapt to changes in the acid value of the oil phase. A second flow meter 215 monitors the flow rate of the second-stage washing unit 200 and adjusts the flow rate of the first outlet 305 via the third regulating valve 213. The second-stage washing unit 200 is also equipped with a second-stage first baffle 202 and a second-stage second baffle 203. Under the guidance of the second-stage first baffle 202 and the second-stage second baffle 203, the aqueous phase moves in a deflected flow and forms a counter-current contact with the oil phase in the floating second-stage annular distributor 204. The aqueous phase is discharged from the second outlet 205. This design can significantly extend the mass transfer time and effectively enhance the neutralization reaction efficiency of organic acids and alkaline components.

[0039] The structure of the first-stage washing unit 100 is similar to that of the second-stage washing unit 200 and the third-stage washing unit 300. The water phase enters the housing 101 of the first-stage washing unit evenly through the second outlet 205 and the three-stage water inlet device 110. The three-stage water inlet device 110 is equipped with a third flow pipe 111 and a third inlet 112. The third flow pipe 111 is connected to the third inlet 112 and the second outlet 205 via a fifth regulating valve 113 and a sixth regulating valve 114, respectively. A third flow meter 115 monitors the flow rate of the first-stage washing unit 100. The water phase at the lower end of the third flow pipe 111 is continuously agitated along the meandering path of the first-stage first baffle 102 and the first-stage second baffle 103, achieving multi-stage micro-interface contact with the oil phase of the first-stage annular distributor 104. The water phase after washing in the first-stage washing unit 100 is discharged through the outlet 105. The external discharge port 105 is equipped with a seventh regulating valve 1052 and a seventh salinity meter 1051. By adjusting the opening of the seventh regulating valve 1052, the outflow rate of the aqueous phase is precisely controlled to ensure the stability of the liquid level and the constant mass transfer time in the first-stage water washing section. The salinity of the aqueous phase is monitored by the seventh salinity meter 1051. At the same time, in coordination with the upstream two-stage water washing, a pH gradient progressive neutralization system is formed. This system automatically maintains the driving force through the liquid level difference of the three-stage water washing, so that the water and salt content of the final outlet oil phase is reduced to the minimum.

[0040] The drain port 106 is a reserved channel at the bottom of the baffle. The drain port 106 can be opened at any position at the bottom of the baffle as a drain port to discharge the residual liquid between the first-stage baffle 102 and the second-stage baffle 103 during the cleaning process, thus facilitating cleaning.

[0041] like Figure 2As shown, the oil phase enters the first-stage annular distributor 104 through the first oil inlet 107. The first oil inlet 107 is equipped with a first pH meter 1010 and a third salinity meter 1011 to monitor the pH and salinity of the oil phase. Under the constraint of the first-stage first baffle 102 and the first-stage second baffle 103, the impact disturbance of the aqueous phase is reduced, thereby enabling sufficient mass transfer between the oil and aqueous phases. After the floating oil phase reaches the liquid surface of the first-stage water washing unit, when its height exceeds the position of the second oil inlet 121, it flows into the first storage tank 123 through the first oil inlet pipe 122. The first oil inlet pipe 122 is a stainless steel pipe with an inner diameter of 150 mm. The second oil inlet 121 is located at the top of the first-stage water washing unit 100. The first-stage water washing unit 100 is equipped with a first interface meter 109 to monitor the interface height between the two phases. The interface height is controlled by adjusting the aqueous phase flow rate to ensure that only the oil phase enters the second oil inlet 121 and that no aqueous phase is mixed in.

[0042] The first storage tank 123 adopts a conical bottom structure design, with the cone and tank body in a 1:2 ratio and a 60° angle between the cone and the tank bottom. The conical tank body is equipped with a waste gas venting pipe, which facilitates the natural dissipation of waste gas and achieves pressure balance. Simultaneously, the conical bottom design also facilitates the venting of the oil phase. The first storage tank 123 is equipped with a second pH meter 126 and a fourth salinity meter 127. The first oil outlet pipe 125 is made of stainless steel with an inner diameter of 50 mm. The first oil outlet pipe 125 is equipped with a primary pump 124. The oil phase in the first storage tank 123 is pumped by the primary pump 124 and transported through the first oil outlet pipe 125 to the secondary ring distributor 204 of the secondary water washing unit 200, allowing the oil phase to float and transfer mass during the secondary water washing process.

[0043] The primary pump 124 and the first storage tank 123 are installed on the annular operating platform of the first-stage water washing unit 100 for easy maintenance and operation.

[0044] The oil phase is uniformly dispersed again in the secondary ring distributor 204 of the second-stage washing unit 200. Guided by the secondary first baffle 202 and the secondary second baffle 203, it comes into countercurrent contact with the fresh water phase, further removing residual salts and acidic impurities. The salinity is controlled by the first salinity meter 208. The floating oil phase crosses the secondary liquid surface and enters the second storage tank 223 through the third oil inlet 221 and the second oil inlet pipe 222. The third oil inlet 221 is located at the top of the second-stage washing unit 200. The second-stage washing unit 200 is also equipped with a second interface meter 207 to monitor the oil-water interface in real time, ensuring that only the oil phase overflows into the second storage tank 223. The second storage tank 223 is equipped with a third pH meter 226 and a fifth salinity meter 227. The oil phase is then pumped by the secondary pump 224 to the tertiary ring distributor 304 of the third-stage washing unit 300 for deep purification.

[0045] In the three-stage annular distributor 304 of the third-stage washing unit 300, the oil phase is further dispersed and comes into countercurrent contact with controlled ultrapure water. Trace residual ions and polar impurities are thoroughly removed, and salinity is controlled by the second salinity meter 108. When the oil phase rises to the third-stage liquid level and passes the fourth oil inlet 321, its cleanliness has reached the industrial-grade limit standard. It then flows into the third storage tank 323 from the third oil inlet pipe 322. The third storage tank 323 is equipped with a fourth pH meter 326 and a sixth salinity meter 327. The fourth oil inlet 321 is located at the top of the third-stage washing unit 300. Here, the third interface meter 307 and the sixth salinity meter 327 work together to ensure that the water and salt content in the final oil phase is reduced to the minimum threshold. The oil phase in the third storage tank 323 is transported to the next stage by the three-stage pump 324 along the third oil outlet pipe 325.

[0046] like Figure 3 As shown, the three-stage annular distributor 304 employs a 316L stainless steel microporous array structure with uniformly distributed pores of 2-4mm diameter, handling 8-18 cubic meters of oil phase per hour. Its distribution ports 3043 are arranged in a ring array, with the distribution channels 3042 between each ring using a 45° staggered design. This ensures the oil phase is uniformly dispersed in the aqueous phase as fine droplets, increasing the contact area between the oil and aqueous phases by 30% and improving mass transfer efficiency by 30%. Furthermore, the annular distributor is made of highly corrosion-resistant stainless steel to adapt to different oil and aqueous phase environments, extending the equipment's service life. After the oil phase enters the annular distributor 304 through the inlet 3041, it diffuses from the inside out through the distribution channels 3042 between the rings, finally exiting from the distribution ports 3043. The secondary annular distributor 204 and the primary annular distributor 104 have the same structure as the three-stage annular distributor 304.

[0047] Example 2: This example discloses a PLC control system integrated on the hardware basis of Example 1, including a PLC electrically connected to sensors such as a pH meter, salinity meter, interface meter, flow meter, and regulating valve. Each sensor collects data in real time and uploads it to the PLC. The PLC adjusts each point according to different water washing process requirements. If different products have different requirements for the salt content in the final oil phase, the PLC controls and adjusts each point accordingly.

[0048] In terms of oil phase control: the oil phase enters the first-stage annular distributor 104 through the first oil inlet 107. The first oil inlet 107 is equipped with a first pH meter 1010 and a third salinity meter 1011 to monitor the initial salt content and acid value of the oil phase in real time. The feedback system data is used to determine the dosage of neutralizing alkali solution. This, combined with the flow rate of the tertiary water inlet device 110 in the first-stage water washing unit 100, determines the flow rate and concentration of the added solution. The first storage tank 123 is equipped with a second pH meter 126 and a fourth salinity meter 127 to monitor the changes in salt content and pH of the oil phase after water washing. The data is fed back to the PLC system in real time. This is used to adjust the water phase flow rate and alkali concentration during water washing, and also provides dynamic calibration data for the water phase flow rate and alkali concentration in the second-stage water washing unit 200.

[0049] After the oil phase enters the second-stage water washing unit 200, the dosage is determined based on data provided by the first-stage water washing unit 100 and the flow rate of the second-stage water inlet device 210. Simultaneously, the salinity and pH changes of the oil phase in the second storage tank 223 are monitored, and the flow rate of the aqueous phase and the concentration of the alkali solution are adjusted accordingly. This provides a dynamic calibration basis for the flow rate of the aqueous phase and the concentration of the alkali solution in the third-stage water washing unit 300. Similarly, the oil phase entering the third-stage water washing unit 300 is again regulated and controlled by the PLC system to stably control the salinity and pH value of the third storage tank 323 within the process value range.

[0050] Regarding water phase control: A salinity meter is installed at the outlet or external discharge port of the third-stage water washing unit 300 to monitor water quality changes after washing in real time. The first-stage water inlet device 310 is equipped with a first regulating valve 313, a second regulating valve 314, and a first flow meter 315 to regulate the water phase flow rate and contact time during washing, ensuring thorough washing.

[0051] The third-stage water washing unit 300 is equipped with a third interface gauge 307 to monitor the interface position between the aqueous and oil phases, ensuring the liquid level remains stable below the oil inlet height (typically set at 70%~95% of the oil inlet height) to prevent backflow of the aqueous phase into the oil phase channel. The third interface gauge 307 feeds back interface information to the PLC system. When the interface shifts upwards, posing a risk of backflow, the PLC automatically increases the flow rate of the third regulating valve 213 in the third-stage water washing unit 300, rapidly reducing the interface height. When the interface shifts downwards to a lower set value, the PLC decreases the opening of the regulating valve to reduce the aqueous phase flow rate.

[0052] Similarly, the first-stage washing unit 100, the second-stage washing unit 200, and the third-stage washing unit 300 are designed in the same way.

[0053] Each adjustment of the valve opening is based on a 10% standard. If the deviation from the target range does not achieve the expected effect, the adjustment is continued in increments of 10%. If the adjustment is too large or too small, the opening is adjusted back by 5%, and so on, until the interface stabilizes within the set range.

[0054] The actual operation control method of this invention is as follows: The oil phase enters the first-stage water washing unit 100 through the first oil inlet 107. After real-time monitoring by a pH meter and a salinity meter, the PLC automatically calculates the amount of alkali solution added at the addition port of the first-stage water washing unit 100. This is coordinated with the water phase flow rate of the three-stage water inlet device 110 to adjust the alkali solution concentration and flow rate, ensuring sufficient neutralization reaction (based on the floating time of the oil phase in the water phase, which is related to the interface height). Subsequently, based on the feedback values ​​from the second pH meter 126 and the fourth salinity meter 127 of the first storage tank 123, the water phase flow rate and alkali solution concentration of the first-stage water washing unit 100 are dynamically corrected, providing a basis for the alkali solution addition amount at the addition port of the second-stage water washing unit 200. Simultaneously, the salinity meters at the outlets of each stage of the water washing process detect whether the adsorption amount of salts in the water phase meets the washing volume requirements for that stage. If there is still a surplus in the washing volume for that stage, the inlet and outlet water volumes are appropriately reduced. However, when there is a conflict between controlling the oil phase desalination and the aqueous phase balance in this stage, the oil phase desalination stage takes precedence. When the salt content in the oil phase is too high, the PLC system will automatically increase the aqueous phase flow rate of the second-stage water washing unit 200 to 1.2 times the design limit, and simultaneously increase the interface height to no more than 95% to prolong the oil-water contact time and enhance the salt extraction efficiency. Similarly, the third-stage water washing unit 300 further optimizes the aqueous phase distribution and alkali gradient addition based on the feedback data from the second-stage water washing unit 200.

[0055] The salinity and pH value of the third storage tank 323 in the third-stage washing unit 300 are kept within the process value range as a priority control target. When the salinity and pH value of each stage show a continuous deviation trend, the opening of the inlet water regulating valve of that stage and the water phase flow rate of the previous stage are adjusted simultaneously to form a cascaded feedback closed loop.

[0056] Control operations for oil phase desalination: Increase the flow rate of the aqueous phase in this stage and raise the interface height (adjust the flow pipe regulating valve and the outlet regulating valve of this stage) to improve mass transfer time and mass transfer efficiency.

[0057] Improve the utilization rate of the aqueous phase: maximize the salt content in the aqueous phase (without affecting the desalination effect of the oil phase), reduce the flow rate of this stage of aqueous phase and increase the interface height to reduce the amount of fresh water replenishment.

[0058] When there is a coupling conflict in the flow rate regulation of the aqueous phase between the upper and lower stages, priority is given to ensuring the desalination effect of the upper stage oil phase, while also considering the load balance of the lower stage aqueous phase. In each stage of water washing, the paths of the oil phase and the aqueous phase are diagonally opposite to each other, maximizing the mass transfer driving force and separation efficiency. At the same time, the three-stage water washing room achieves parameter linkage regulation through a closed-loop feedback system—the water quality data of the upper stage drives the millisecond-level response of the flow rate and concentration of the aqueous phase in the lower stage in real time, ensuring stable and controllable purification accuracy throughout the entire chain. The flow rate ratio of the aqueous phase and the oil phase strictly follows the Froude number critical criterion to ensure interface stability and prevent emulsification; the flow rate of the aqueous phase is set at a critical value that does not interfere with the upward floating path of the oil phase, while the minimum droplet limit of the oil phase is set at a value that does not exhibit emulsification, under which mass transfer contact takes place.

[0059] In each stage of the water wash, the oil and water phases follow opposite diagonal paths, maximizing mass transfer driving force and separation efficiency. The water phase flows downwards under gravity through each stage of the wash, requiring no pump and consuming almost no energy. The oil phase, on the other hand, rises naturally in each stage of the wash due to buoyancy, its path refined through a three-stage distributor, with droplet diameter strictly controlled within the 2-4 mm range. This ensures sufficient mass transfer while preventing secondary emulsification. This ingenious fluid dynamics design allows oil droplets to continuously undergo a four-stage dynamic equilibrium of "dispersion-contact-coalescing-floating" during their ascent. The downward flow of the water phase results in a gradual increase in salt content at each stage, while the oil phase achieves gradient removal of impurities during its ascent, leading to an exponential increase in cleanliness.

[0060] Example 3: This example demonstrates how the number of washing stages can be flexibly configured based on the different process requirements and energy-saving standards of various products, while maintaining the control logic unchanged. For instance, a two-stage washing structure can be used for oils with low salinity requirements to simplify the process and reduce energy consumption; while for oils with stringent salinity control, a four-stage washing unit is required. Increasing the number of washing stages leads to higher costs, but also results in more stable control and higher oil quality. Furthermore, five-stage and higher washing structures are suitable for the production of ultra-clean oils. While increasing costs, they significantly improve system redundancy and anti-interference capabilities, maintaining the final oil's salinity content within a range of ±30% fluctuation in raw material salinity. In practical applications, three-stage washing is a common balance point, balancing energy efficiency, cost, and quality stability.

[0061] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the scope of the claims of the present invention should be within the protection scope of the present invention.

Claims

1. An intelligent multi-stage countercurrent water washing control device, comprising a storage tank and an oil inlet, characterized in that, It also has two or more sets of water washing units, which are stacked and installed. Each water washing unit has a housing. The top of the housing has a water inlet device and an oil outlet. The water inlet device has a water inlet and a flow meter. The bottom of the housing has an annular liquid distributor and a water outlet. The annular liquid distributor is connected to the oil inlet. The annular liquid distributor is surrounded by a baffle structure to stabilize the water flow. The water outlet of the upper washing unit is connected to the water inlet of the lower washing unit, and the oil outlet of the lower washing unit is connected to the oil inlet of the upper washing unit. The oil outlet is connected to a storage tank through an oil inlet pipe, and the storage tank is connected to the oil inlet of the upper washing unit through an oil outlet pipe. A pump is installed on the oil outlet pipe. The washing unit is also equipped with a PLC feedback system, which includes a PLC, a sensor for sensing the liquid state in the washing unit, and a regulating valve for controlling the liquid flow. The PLC is electrically connected to the sensor and the regulating valve.

2. The intelligent multi-stage countercurrent water washing control device according to claim 1, characterized in that, The sensors include an interface meter and a flow meter located inside the washing unit housing, a salinity meter located at the outlet of the washing unit, and a pH meter and a salinity meter located inside the storage tank.

3. The intelligent multi-stage countercurrent water washing control device according to claim 1, characterized in that, The water inlet device is also provided with an inlet, and an inlet regulating valve is provided between the water inlet device and the inlet, and the inlet regulating valve is electrically connected to the PLC.

4. The intelligent multi-stage countercurrent water washing control device according to claim 1, characterized in that, The bottom water washing unit is also equipped with a pH meter and a salinity meter at the oil inlet.

5. A control method for an intelligent multi-stage counter-current water washing control device, which employs the intelligent multi-stage counter-current water washing control device as described in any one of claims 1-4, characterized in that, Includes the following steps: Step 1: After the aqueous phase enters the upper water washing unit, it is mixed and washed with the oil phase discharged from the middle water washing unit. The PLC acquires the oil phase data discharged from the middle water washing unit and uses an interface meter, regulating valve and flow meter to stably control the oil-water interface. The salinity and pH value of the upper water washing unit storage tank are monitored in real time by the pH meter and salinity meter of the storage tank to control the flow rate and concentration of the additive liquid and ensure that the oil phase is within the process value range. Step 2: After being washed by the upper water washing unit, the aqueous phase enters the middle water washing unit, where it is mixed and washed again with the oil phase discharged from the lower water washing unit. The PLC acquires the oil phase data discharged from the lower water washing unit and uses an interface meter, regulating valve, and flow meter to stably control the oil-water interface. The salinity and pH value of the middle water washing unit storage tank are monitored in real time by the pH meter and salinity meter in the storage tank to control the flow rate and concentration of the additive solution, and to provide a dynamic calibration basis for the aqueous phase flow rate and alkali concentration in Step 1. Step 3: After being washed by the middle layer water washing unit, the aqueous phase enters the lower layer water washing unit, where it is mixed and washed with the oil phase discharged from the lower layer water washing unit. The PLC uses an interface meter, regulating valve, and flow meter to stably control the oil-water interface. The salinity and pH value of the lower layer water washing unit storage tank are monitored in real time by the pH meter and salinity meter in the storage tank, which controls the flow rate and concentration of the additive solution and provides a dynamic calibration basis for the aqueous phase flow rate and alkali concentration in Step 2. Step 4: Discharge the aqueous phase after three-stage water washing and obtain the oil phase after three-stage water washing in Step 1.

6. The control method of the intelligent multi-stage countercurrent water washing control device according to claim 5, characterized in that, The opening of the regulating valve is adjusted in increments of 10%. If the desired effect is not achieved after deviating from the target range, the adjustment is continued in increments of 10%. If the adjustment is too large or too small, the opening is adjusted back by 5%, and so on, until the interface stabilizes within the set range.

7. The control method of the intelligent multi-stage countercurrent water washing control device according to claim 5, characterized in that, When there is a coupling conflict between the water phase flow rate regulation of the preceding and subsequent steps, priority should be given to ensuring the desalination effect of the oil phase in the preceding step, while also taking into account the water phase load balance in the subsequent step.

8. The control method of the intelligent multi-stage countercurrent water washing control device according to claim 5, characterized in that, In step one, the salinity and pH of the storage tank are the priority control targets. The PLC dynamically adjusts the water phase flow rate and alkali dosage of the next stage of water washing based on the feedback values ​​from the salinity meter and pH meter in the storage tank.

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