Method and system for realizing boundary position control and oil-water separation of full-closed sewage conveying unit

Abstract

The present application relates to a kind of method and system for realizing sewage full-closed conveying unit boundary position control and oil-water separation, to solve the problem of poor water quality effect.Closed horizontal long horizontal sewage tank bottom wall is sequentially spaced along long axis with inner low-position feed pipe and inner high-position oil cutting pipe and sunken sludge chamber, horizontal sewage tank side wall is provided with high-position medium sensor higher than the inlet of inner high-position oil cutting pipe in the region between inner high-position oil cutting pipe and sunken sludge chamber, low-bottom medium sensor is respectively provided at the height of inner high-position oil cutting pipe inlet and inner low-position feed pipe outlet, and sludge medium detection sensor is provided on the side wall of sunken sludge chamber;Pressure transmitter sensor of pressure gauge and electrically connected intelligent controller is connected at the top of horizontal sewage tank, under the control of medium sensor and intelligent control, oil return and large-flow drainage, small-flow drainage and dredging signal are sent.The present application has the advantages of easy separation of oil and sludge, real-time online detection, accurate oil-water separation, closed sewage conveying self-adaptation and good water quality effect.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for separating and discharging oil-containing sewage from petrochemical process devices, and particularly to a method and system for realizing boundary position control and oil-water separation and discharge of a fully-closed sewage conveying unit. BACKGROUND

[0002] In the petrochemical industry, the sewage discharged from various process devices inevitably contains oil medium. If the oil-containing medium is directly discharged into a sewage pipe network system or a sewage pool, not only oil medium is wasted, but also the environment is polluted, and toxic gas may be discharged, endangering life. More seriously, oil-containing medium may gather in a low concave part of a pipeline, and cause fire or even explosion when meeting an open flame, resulting in significant economic loss and personal injury. Although a primary water cutting device is provided for each storage tank, the water cut by the primary water cutting device still contains oil. Although a secondary water cutting device is connected after the primary water cutting device, the secondary water cutting device cannot meet the practical needs in water cutting efficiency, for example, the secondary water cutting device has high water content, low oil content, and it is more difficult to separate oil and sludge. SUMMARY

[0003] The present application aims to overcome the above-mentioned defects of the prior art, and provides a method for realizing boundary position control and oil-water separation and discharge of a fully-closed sewage conveying unit, and also provides a system for realizing the method. The method and system can easily separate oil and sludge, and have good water cutting efficiency.

[0004] The application is characterized in that the bottom wall of the horizontal long sewage tank is sequentially provided with an inner low-position feeding pipe and an inner high-position oil cutting pipe and a sunken sludge cavity along the long axis; the side wall of the horizontal long sewage tank is provided with a high-position medium sensor higher than the inlet of the inner high-position oil cutting pipe between the inner high-position oil cutting pipe and the sunken sludge cavity; low bottom-position medium sensors are arranged at least at the height of the inlet of the inner high-position oil cutting pipe and the outlet of the inner low-position feeding pipe; a sludge medium detection sensor is arranged on the side wall of the sunken sludge cavity; a pressure transmitter sensor of the pressure gauge and the intelligent electric controller is connected to the top of the horizontal long sewage tank; a liquid level meter of the intelligent electric controller is connected to the downstream end of the horizontal long sewage tank; the inner low-position feeding pipe feeds in the set gas phase pressure and liquid level range through the water cutting pipeline connected to the storage tank; the inner high-position oil cutting pipe returns oil when the detection signals of the high-position and low-position medium sensors are both oil, which can ensure the quality of the returned oil; the sunken sludge cavity is connected to the sludge discharge valve pipeline and the variable flow drainage pump valve pipeline connected to the sewage storage facility, and when the detection signals of the high-position and low-position medium sensors are both water, the sunken sludge cavity performs large flow drainage and small flow drainage in the water level range of the low bottom-position medium sensor, which can significantly improve the water cutting quality; when the sludge medium detection sensor detects sludge, the intelligent controller sends a dredging signal to discharge sludge manually, which can avoid the discharge of oily sludge with water and additional burden on sewage treatment. The height of the inner high-position oil cutting pipe is about 3 / 4 of the height of the inner cavity of the horizontal long sewage tank, and the height of the inner low-position feeding pipe is 5-9% of the height of the inner cavity of the horizontal long sewage tank. The application has the advantages of easy separation of oil and sludge and good water cutting and oil returning quality.

[0005] As an optimization, a safety valve and a pressure relief valve pipe are connected to the top upstream side of the horizontal long sewage tank, which is beneficial to sensitive response to abnormal feeding pressure; a sludge blowing valve pipe lower than the inlet of the inner low-position feeding pipe is connected to the end wall of the horizontal long sewage tank on the upstream side; the pressurizing pump valve pipe connected to the top of the horizontal long sewage tank blows gas into the horizontal long sewage tank through the sludge blowing valve pipe to blow the sludge at the bottom of the horizontal long sewage tank to the downstream direction where the sunken sludge cavity is located, which can well avoid sludge accumulation at the bottom of the tank. A safety valve and two spaced parallel pressure relief valve pipes, a vent valve pipe, a standby valve pipe, a pressure gauge, a pressure transmitter sensor and two spaced parallel standby valve pipes are sequentially and spaced connected to the top of the horizontal long sewage tank from the upstream end to the downstream end. The two spaced parallel pressure relief valve pipes and the vent valve pipe are jointly connected to a vent tail pipe. The standby valve pipe of the top of the horizontal long sewage tank is connected to the pressurizing pump valve pipe. The pressure gauge and the pressure transmitter sensor are arranged in the middle between the upstream and the downstream of the top of the horizontal long sewage tank, which is beneficial to timely and comprehensive sensing of the gas phase pressure change in the tank.

[0006] As an optimization, a sludge visual inspection window valve pipe is arranged on the bottom of the horizontal sewage tank and is connected to the downstream side of the inner low-position feed pipe, and when sludge is found in the sludge visual inspection window, a pressurized pump valve pipe is opened to blow the sludge at the bottom of the horizontal sewage tank to the downstream side; after the blowing, a lower discharge valve of the sludge visual inspection window valve pipe is opened to discharge the sludge in the sludge visual inspection window, and then the lower discharge valve is closed. In this way, the sludge entering the tank bottom can be found in time, and the downstream blowing can be performed in time, which is more conducive to timely removal of the sludge.

[0007] As an optimization, a temperature table and a temperature transmitting sensor of an intelligent controller are arranged on the side wall of the horizontal sewage tank and are at least as high as the inner low-position feed pipe, the intelligent controller controls the flow rate according to the temperature to control the oil return and water discharge, and the temperature table and the temperature transmitting sensor of the intelligent controller are arranged on the side wall of the horizontal sewage tank and are at least as high as the inner low-position feed pipe, the intelligent controller controls the flow rate according to the temperature to control the oil return and water discharge; when the temperature is low, the flow rate is small, the oil return and water discharge are controlled, when the temperature is high, the flow rate is large, the oil return and water discharge are controlled, which can fully utilize the high-temperature water to improve the water discharge efficiency, and can solve the problem of low-temperature water that is not easy to separate, and avoid the problem of rapid water separation with oil entrainment; a liquid level meter of an intelligent controller is arranged on the upstream and downstream end walls of the horizontal sewage tank, the liquid level meter controls the highest and lowest liquid levels in the horizontal sewage tank through the controller, and the liquid level backup associated control is performed in combination with the liquid level detection signals of the high-position and low-position medium sensors, so that the horizontal sewage tank can be stably operated under the premise of ensuring the liquid level. The temperature table and the temperature transmitting sensor of the intelligent controller are arranged on the side wall of the horizontal sewage tank and are at least as high as the inner low-position feed pipe, which can better sense the oil return temperature, so as to accurately control the oil return flow rate according to the oil temperature.

[0008] As an optimization, a sludge visual inspection window valve pipe is arranged on the bottom of the horizontal sewage tank and is connected to the downstream side of the inner low-position feed pipe, and when sludge is found in the sludge visual inspection window, a pressurized pump valve pipe is opened to blow the sludge at the bottom of the horizontal sewage tank to the downstream side; after the blowing, a lower discharge valve of the sludge visual inspection window valve pipe is opened to discharge the sludge in the sludge visual inspection window, and then the lower discharge valve is closed. In this way, the sludge entering the tank bottom can be found in time, and the downstream blowing can be performed in time, which is more conducive to timely removal of the sludge.

[0009] As an optimization, the inner low-position feed pipe and the inner high-position oil cutting pipe are vertical pipes, the upper ends of which are connected to the horizontal pipes extending to both ends, and the horizontal pipes are used for feeding and discharging to reduce the disturbance of the layered interface by the liquid flow; the inner low-position feed pipe and the inner high-position oil cutting pipe are respectively arranged at the front and rear parts of the upstream section of the horizontal sewage tank, and the sunken sludge cavity is arranged at the middle part of the downstream section of the horizontal sewage tank, so as to increase the upward layered path of the oil and sludge and reduce the mixing opportunity of the sludge.

[0010] As optimization, the oil return pump valve pipeline is an oil return pipe connected in sequence with an oil return pump, an oil return delivery regulating valve, an oil return pressure gauge, an oil return flow meter and an oil return control valve below a horizontal sewage tank communicated with an inner low feeding pipe; the variable flow drainage pump valve pipeline is a drainage pipe connected in sequence with a sewage pump, a sewage delivery regulating valve, a sewage pressure gauge, a sewage flow meter and a drainage control valve below the horizontal sewage tank communicated with an inner high feeding pipe, and variable flow oil return and drainage are performed under the control of an intelligent controller. At least the oil return pump, the oil return delivery regulating valve, the oil return flow meter and the oil return control valve are electrically connected to the intelligent controller, and at least the sewage pump, the sewage delivery regulating valve, the sewage flow meter and the drainage control valve are electrically connected to the intelligent controller.

[0011] The main working process is that the sewage from the previous process device is subjected to secondary sedimentation in the sewage tank after entering the sewage tank of the sewage collection and delivery unit. The control system of the system automatically starts the oil return pump and the water delivery pump according to the detection signal of the oil-water detection sensor of the sewage tank and the set sedimentation time. The specific process is as follows.

[0012] (1) The sewage tank mainly functions as: a. collecting and temporarily storing the oil-containing sewage from each storage tank; b. providing a secondary sedimentation and separation environment for the oil-containing sewage and a secondary sedimentation environment for impurities; c. realizing oil-water separation through oil-water detection and control; and d. sending a desilting signal when the impurities in the sewage tank accumulate to a set value.

[0013] Working process: a. Waiting state: water cutting valve is closed, each unit pump stops running, and other on-off valves are in closed state. b. Sewage entering: sewage from the upper process device continuously enters the sewage tank, the liquid level in the tank rises until the sewage entering stops when the liquid level reaches the high set value; other unit pumps are in stop state and control valves are in closed state. c. Sedimentation separation: sewage entering stops, each unit pump stops running and each unit control valve is closed, the liquid level and pressure in the tank are in stable state, and sewage is subjected to secondary sedimentation separation. d. Sewage discharge: when the liquid level in the sewage tank reaches the high set value and the sedimentation separation time reaches the set value, the water inlet pump of the upper process device stops and the water inlet valve is closed, the sewage conveying unit pump stops and the valve is closed, the sewage discharge unit pump starts and the valve is opened, and the sewage in the tank is continuously discharged. When the liquid level in the tank decreases to the low set value, the sewage conveying unit variable flow conveying module discharges sewage at a small flow rate. When the oil-water detection signal of the oil-water detection sensor at the bottom of the sewage tank reaches the set value, the sewage conveying unit pump stops running and the valve is closed. e. Sewage oil separation: when the liquid level in the sewage tank reaches the high set value, the high and low medium detection sensor signals are both oil signals, and the sedimentation separation time reaches the set value, the water inlet pump of the upper process device stops and the water inlet valve is closed, the sewage discharge unit pump stops and the valve is closed, and the sewage oil conveying unit pump starts to convey the sewage oil to a designated container. When the liquid level in the tank decreases to the position of the low medium detection sensor, the sewage oil conveying unit pump stops and the valve is closed. f. Sludge detection and alarm: during the operation of the sewage tank, the sludge medium detection sensor is always in working state, and when the sludge in the tank reaches the set value, an automatic alarm signal is sent.

[0014] (2) The sewage discharge unit mainly composed of a variable flow drainage pump valve pipeline, mainly functions: a. conveying the sewage in the sewage tank to the tank area sewage pipeline; b. when the oil-water interface or liquid level in the sewage tank decreases to the installation position of the low medium detection sensor, the pump of the sewage conveying unit automatically reduces the output flow, thereby minimizing the vortex generated by large flow at the oil-water interface in the sewage tank, resulting in incomplete sewage discharge.

[0015] Working process: a. Waiting state: when the liquid level in the sewage tank does not reach the high medium detection sensor installation position, the settling time does not reach the set value, the pump stops, the valve closes, and the sewage discharge unit stops running, in the waiting state. b. Discharge state: when the sewage in the tank settles for a set time, the liquid level in the tank is at the high sensor installation position, the inlet pump of the previous process device stops, the inlet valve closes, the sewage oil delivery unit pump stops, the valve closes, the sewage discharge unit pump starts, and the sewage in the tank is discharged to the tank area sewage pipeline. c. Small flow discharge: when the oil-water interface or liquid level in the tank drops to the low sensor installation position, the variable flow control module of the sewage discharge unit automatically switches to small flow output. d. Discharge stop: when the oil-water detection signal of the medium detection sensor installed at the bottom of the sewage tank is oil, the pump of the discharge unit automatically stops, and the sewage discharge process ends.

[0016] (3) The sewage oil delivery unit mainly composed of an oil return pump valve pipeline, the main function: to transport the sewage oil in the sewage tank to the designated container. Working process: a. Waiting state: when the high and low medium detection sensor signals of the sewage tank are not all oil signals, the pump stops, the valve closes. b. Transport state: when the high and low medium detection sensors of the sewage tank are all oil signals, the pump starts, the valve opens, and the sewage oil in the tank is transported to the designated container through the pipeline. c. Transport stop: when the high and low medium detection sensors of the sewage tank are all non-oil signals, the pump stops, the valve closes.

[0017] The system for realizing the method for realizing the position control and oil-water separation of the full-closed sewage conveying unit of the application is characterized in that the bottom wall of the horizontal long sewage tank is sequentially provided with an upstream inner low feeding pipe and an upstream inner high oil cutting pipe and a downstream sunken sludge cavity along the long axis; the side wall of the horizontal sewage tank is provided with a high medium sensor higher than the inlet of the inner high oil cutting pipe between the inner high oil cutting pipe and the sunken sludge cavity; low bottom medium sensors are arranged at least at the height of the inlet of the inner high oil cutting pipe and the height of the outlet of the inner low feeding pipe; a sludge medium detection sensor is arranged on the side wall of the sunken sludge cavity; a pressure transmitter sensor of the pressure sensor and the intelligent controller is connected to the top of the horizontal sewage tank; a liquid level meter of the intelligent controller is connected to the downstream end of the horizontal sewage tank; the inner low feeding pipe is connected to the water cutting pipeline of the storage tank downward; the inner high oil cutting pipe is connected to the oil return pump valve pipeline of the storage tank downward; the sunken sludge cavity is connected to the sludge discharge valve pipeline and the variable flow drainage pump valve pipeline leading to the sewage storage facility; when the sludge medium detection sensor detects sludge, a dredging signal is sent through the intelligent controller; the inner low feeding pipe feeds in the set gas phase pressure and liquid level range through the water cutting pipeline connected to the storage tank; the inner high oil cutting pipe returns oil when the high and low medium sensors detect signals of oil; the quality of the returned oil can be guaranteed; the sunken sludge cavity is connected to the sludge discharge valve pipeline and the variable flow drainage pump valve pipeline connected to the sewage storage facility; when the high and low medium sensors detect signals of water, large flow drainage is performed; when the water level of the low bottom medium sensor is in the range, small flow drainage is performed; the quality of the cut water can be significantly improved; when the sludge medium detection sensor detects sludge, a dredging signal is sent through the intelligent controller; dredging is performed; timely sludge detection and dredging are more conducive to ensuring the quality of the separation; the height of the inner high oil cutting pipe is about 3 / 4 of the height of the inner cavity of the horizontal long sewage tank; the height of the inner low feeding pipe is 5-9% of the height of the inner cavity of the horizontal long sewage tank.

[0018] The safety valve and the pressure relief valve pipe are communicated on the upstream side of the top of the horizontal sewage tank, which is beneficial to ensure safe operation; the sludge blowing valve pipe lower than the inner low-level feeding pipe is communicated on the upstream end wall of the horizontal sewage tank, the pressurizing pump valve pipe communicated on the top of the horizontal sewage tank blows gas into the horizontal sewage tank through the sludge blowing valve pipe to blow the sludge at the bottom of the horizontal sewage tank to the downstream direction where the subsided sludge chamber is located, which can well avoid sludge accumulation at the bottom of the tank. The sludge visual inspection window valve pipe is downwardly communicated on the downstream side of the inner low-level feeding pipe at the bottom of the horizontal sewage tank, when sludge is found to enter the sludge visual inspection window, the pressurizing pump valve pipe is opened to blow the sludge at the bottom of the horizontal sewage tank to the downstream side; after blowing, the lower discharge valve of the sludge visual inspection window valve pipe is opened to empty the sludge in the sludge visual inspection window, and then the lower discharge valve is closed. In this way, the sludge entering the tank bottom can be found in time, and the sludge can be blown to the downstream in time, which is more conducive to timely removal of sludge. The safety valve and two spaced parallel pressure relief valve pipes, as well as the vent valve pipe, the standby valve pipe, the pressure gauge, the pressure variable transmission sensor and two spaced parallel standby valve pipes are sequentially and spacedly communicated on the top of the horizontal sewage tank from the upstream end to the downstream end. The two spaced parallel pressure relief valve pipes and the vent valve pipe are jointly communicated with the vent tail pipe. The standby valve pipe on the top of the horizontal sewage tank is communicated with the pressurizing pump valve pipe. The pressure gauge and the pressure variable transmission sensor are arranged on the top of the horizontal sewage tank between the upstream and the downstream, which is beneficial to timely and comprehensive sensing of the change of the gas phase pressure in the tank.

[0019] The temperature gauge and the temperature variable transmission sensor of the electrically connected intelligent controller are arranged on the side wall of the horizontal sewage tank between the inner high-level oil cutting pipe and the bottom medium sensor at a height at least flush with the inner low-level feeding pipe, the intelligent controller controls the oil return and drainage according to the temperature: low temperature controls small flow for oil return and drainage, and high temperature controls large flow for oil return and drainage, which can fully utilize high-temperature easy water separation to improve the drainage efficiency, and can solve the problem of low-temperature difficult water separation and avoid the problem of rapid water separation entraining dirty oil; the liquid level meter of the electrically connected intelligent controller is arranged on the lower end of the downstream end wall of the horizontal sewage tank, the liquid level meter controls the highest and lowest liquid level in the horizontal sewage tank through the controller, and combines the liquid level detection signal of the high and low bottom medium sensor for backup associated control, which ensures stable operation under the premise of ensuring the liquid level. The temperature gauge and the temperature variable transmission sensor of the electrically connected intelligent controller are arranged on the side wall of the horizontal sewage tank between the inner high-level oil cutting pipe and the bottom medium sensor at a height close to the inner high-level oil cutting pipe and at least flush with the inner low-level feeding pipe, which can better sense the oil return temperature and thus accurately control the oil return flow rate according to the oil temperature.

[0020] The bottom between the inner high oil cutting pipe and the sunken oil sludge cavity and the bottom of the sunken oil sludge cavity are respectively connected downward to the oil sludge valve pipe for manual downward sludge discharge, so that the sludge can be better avoided from accumulating in the tank bottom; the two outer convex ends of the horizontal sewage tank are respectively sealed and equipped with manhole covers through manhole flanges and standard fasteners, when the downward sludge discharge is ineffective, people can enter for sludge discharge, and at least two sets of equipment are used for sludge discharge operation in rotation, so as to solve the problem that the oil sludge is easy to accumulate and affects the normal operation of the equipment.

[0021] As an optimization, the inner low feeding pipe and the inner high oil cutting pipe are vertical pipes connected to the horizontal pipes extending to both ends, the inner low feeding pipe and the inner high oil cutting pipe are respectively located at the front and rear of the upstream section of the horizontal sewage tank, and the sunken oil sludge cavity is located in the middle of the downstream section of the horizontal sewage tank. The inner low feeding pipe and the inner high oil cutting pipe are vertical pipes connected to the horizontal pipes extending to both ends, the horizontal pipes are used for feeding and discharging materials at both ends to reduce the disturbance of the layered interface by the liquid flow; the inner low feeding pipe and the inner high oil cutting pipe are respectively located at the front and rear of the upstream section of the horizontal sewage tank, and the sunken oil sludge cavity is located in the middle of the downstream section of the horizontal sewage tank, so as to increase the upward layered path of the contaminated oil and reduce the opportunity of sludge mixing.

[0022] The oil return pump valve line is an oil return pipe connected to the horizontal sewage tank below the inner low feeding pipe, and sequentially provided with an oil pump, an oil return conveying adjustment valve, an oil pressure gauge, an oil flow meter and an oil return control valve; the variable flow drainage pump valve line is a drainage pipe connected to the horizontal sewage tank below the inner high feeding pipe, and sequentially provided with a sewage pump, a sewage conveying adjustment valve, a sewage pressure gauge, a sewage flow meter and a drainage control valve, and the variable flow oil return and drainage are performed under the control of the intelligent controller. At least the oil pump, the oil return conveying adjustment valve, the oil flow meter and the oil return control valve are electrically connected to the intelligent controller, and at least the sewage pump, the sewage conveying adjustment valve, the sewage flow meter and the drainage control valve are electrically connected to the intelligent controller.

[0023] The system of the method mainly consists of the following parts: sewage tank, medium detection sensor, intelligent controller, pressure transmission sensor, temperature transmission sensor, liquid level meter, control valve, oil return pump, sewage pump, flow meter and connecting pipeline, manual valve and other accessories. The boundary level control of the sewage closed conveying unit and the configuration and arrangement of the oil-water separation device. All medium detection sensors are electrically connected to the intelligent controller, and the oil-water detection sensor converts the detection signal into an electric signal and transmits it to the intelligent controller. The intelligent controller judges the oil-water condition in the sewage tank through identification and analysis of the oil-water detection signal and controls the valve and pump, realizing the boundary level control of the oil-water in the sewage tank and the oil-water separation. The intelligent controller also has the function of transmitting the judgment signal to the monitoring system. In the present application, double safety relief valve pipes are arranged on the upper part of the sewage tank to ensure that the pressure in the sewage tank is maintained within a certain range, realizing the method of full sealing, isolation and low-pressure discharge of the sewage in the sewage tank. In the present application, pressure transmission sensor, temperature transmission sensor and liquid level meter are arranged on the upper part of the sewage tank and connected with the intelligent controller, realizing online real-time monitoring of temperature, pressure and liquid level, and achieving safety protection of the sewage tank through changes in temperature, pressure and liquid level signals. In the present application, the sewage collection and distribution unit is provided with a sewage conveying regulating valve, which is electrically connected to the intelligent controller. The intelligent controller realizes the opening, closing and opening degree adjustment of the sewage conveying regulating valve through identification and analysis of the sewage tank oil-water detection sensor detection signal, realizing the variable flow closed remote conveying of the sewage. In the present application, the sewage collection and distribution unit is provided with a sewage conveying pump, which is electrically connected to the intelligent controller. The intelligent controller realizes the opening or closing operation of the sewage conveying pump through identification and analysis of the sewage tank oil-water detection sensor detection signal and according to the pressure detection of the sewage tank, realizing the forced remote conveying of the sewage in the sewage tank. In the present application, the sewage collection and distribution unit is provided with an oil return conveying regulating valve, which is electrically connected to the intelligent controller. The intelligent controller realizes the opening or closing operation of the oil return conveying regulating valve through identification and analysis of the sewage tank oil-water detection sensor detection signal, realizing the return of the oil-containing medium in the sewage tank to the storage tank. In the present application, the sewage collection and distribution unit is provided with an oil return conveying pump, which is electrically connected to the intelligent controller. The intelligent controller realizes the opening or closing operation of the oil return conveying pump through identification and analysis of the sewage tank oil-water detection sensor detection signal and according to the pressure detection of the sewage tank, realizing the forced return of the oil-containing medium in the sewage tank to the storage tank. In the present application, as an optimization, the sewage collection and distribution unit is provided with a flow meter, which is electrically connected to the intelligent controller. The intelligent controller realizes the control of the control valve, sewage conveying pump and oil return conveying pump through real-time online monitoring of the flow meter, ensuring that the sewage conveying flow and oil conveying flow match the storage amount of oil and water in the sewage tank.In the present application, the sewage collecting and distributing unit is provided with a sludge chamber, the sludge chamber is provided with a sludge medium detection sensor, and is electrically connected to an intelligent controller, so as to realize real-time online detection of sludge, that is, the sludge detection sensor is always in working state during the operation of the sewage collecting and distributing unit, and an alarm signal is automatically sent when the sludge in the tank reaches the set value. In the present application, the sewage collecting and distributing unit is operated in a fully closed mode, without the need of nitrogen line and oil gas recovery line, and the system is controlled by various detection instruments and intelligent controllers, so that the sewage tank reaches gas phase pressure balance, and no organic gas is discharged during the operation of the system, with small investment, low operation cost, and working pressure range of 0.01-0.3 MPa.

[0024] In summary, the method and system of the present application automatically control the automatic operation of the sewage collecting and distributing pump, the sewage recovery pump and the related valves according to the signals of the high, low and bottom oil-water medium detection sensors of the sewage tank. The boundary position control and oil-water distribution of the sewage closed conveying unit are realized by using the recognition and control of the signals of the oil-water detection sensors and the setting of the sludge chamber of the sewage tank. The method and system of the present application have the functions of fully closed remote conveying, real-time online detection of oil and water, accurate oil-water distribution, variable flow control, accurate oil-water detection, sludge detection and alarm, automatic monitoring of the whole process and real-time signal remote transmission, etc. The system formed by applying the method can be fully automatically operated and information can be remotely transmitted, and can also be semi-automatically operated under remote control. The application of the method can realize fully closed remote conveying and oil-water distribution of single storage tank, and can also realize centralized fully closed remote conveying and oil-water distribution of multiple storage tanks. The sewage tank is used to realize secondary settlement and separation of oily sewage, and through accurate detection of the oil-water interface in the sewage tank, oil medium is automatically returned and sewage is discharged under the control of low-position water seal.

[0025] In summary, the method and system for realizing boundary position control and oil-water distribution of the sewage closed conveying unit have the advantages of easy separation of oil and sludge, real-time online detection, accurate oil-water distribution, self-adaptation of sewage closed conveying, and good quality and effect of cut-water and oil return. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a structural schematic diagram of a system for realizing the method for realizing boundary position control and oil-water distribution of the sewage closed conveying unit. DETAILED DESCRIPTION

[0027] The method for realizing the level control and oil-water separation of the full-closed sewage conveying unit is that a low-level feeding pipe and a high-level oil cutting pipe and a sunken sludge cavity are arranged on the bottom wall of the horizontal long sewage tank along the long axis line in sequence, a high-level medium sensor higher than the inlet of the high-level oil cutting pipe is arranged on the side wall of the horizontal long sewage tank between the high-level oil cutting pipe and the sunken sludge cavity, low-bottom medium sensors are arranged at least at the height of the inlet of the high-level oil cutting pipe and the outlet of the low-level feeding pipe, and a sludge medium detection sensor is arranged on the side wall of the sunken sludge cavity; a pressure transmitter sensor of the pressure gauge and the electric intelligent controller is connected to the top of the horizontal long sewage tank, and a liquid level meter of the electric intelligent controller is connected to the downstream end of the horizontal long sewage tank; the low-level feeding pipe feeds in the set gas phase pressure and liquid level range through the water cutting pipeline connected to the storage tank; the high-level oil cutting pipe returns oil when the detection signals of the high-level and low-level medium sensors are both oil through the oil return pump valve pipeline connected to the storage tank; the sunken sludge cavity is connected to the sludge discharge valve pipeline and the variable flow drainage pump valve pipeline connected to the sewage storage facility, and when the detection signals of the high-level and low-level medium sensors are both water, the sunken sludge cavity performs large flow drainage and small flow drainage in the water level range of the low-bottom medium sensor; when the sludge medium detection sensor detects sludge, the intelligent controller sends a dredging signal; the height of the high-level oil cutting pipe is about 3 / 4 of the height of the inner cavity of the horizontal long sewage tank, and the height of the low-level feeding pipe is 5-9% of the height of the inner cavity of the horizontal long sewage tank.

[0028] A safety valve and a pressure relief valve pipe are connected to the top upstream side of the horizontal long sewage tank, a sludge blowing valve pipe lower than the inlet of the low-level feeding pipe is connected to the upstream end wall of the horizontal long sewage tank, and the pressurizing pump valve pipe connected to the top of the horizontal long sewage tank blows gas into the horizontal long sewage tank through the sludge blowing valve pipe to blow the sludge at the bottom of the horizontal long sewage tank to the downstream direction where the sunken sludge cavity is located. A sludge visual inspection window valve pipe is connected to the bottom of the horizontal long sewage tank downstream of the low-level feeding pipe, and when sludge is found in the sludge visual inspection window, the pressurizing pump valve pipe is opened to blow the sludge at the bottom of the horizontal long sewage tank to the downstream side; after blowing, the lower discharge valve of the sludge visual inspection window valve pipe is opened to discharge the sludge in the sludge visual inspection window, and then the lower discharge valve is closed. A safety valve and two spaced parallel pressure relief valve pipes, a vent valve pipe, a standby valve pipe, a pressure gauge, a pressure transmitter sensor and two spaced parallel standby valve pipes are sequentially and spaced connected to the top of the horizontal long sewage tank from the upstream end to the downstream end. The two spaced parallel pressure relief valve pipes and the vent valve pipe are jointly connected to a vent tail pipe. The standby valve pipe of the top of the horizontal long sewage tank is connected to the pressurizing pump valve pipe. The pressure gauge and the pressure transmitter sensor are arranged on the middle part between the upstream and the downstream of the top of the horizontal long sewage tank, which is beneficial to timely and comprehensive sensing of the gas phase pressure change in the tank.

[0029] The temperature table and the temperature variable sending sensor of the electrically connected intelligent controller are arranged in the area close to the inner high-position oil cutting pipe between the inner high-position oil cutting pipe and the bottom medium sensor of the side wall of the horizontal sewage tank, and the height is at least flush with the inner low-position feeding pipe, the intelligent controller controls the oil return and drainage according to the temperature, that is, the oil return and drainage are controlled at a small flow when the temperature is low, and the oil return and drainage are controlled at a large flow when the temperature is high; the liquid level meter of the electrically connected intelligent controller is arranged on the upper and lower end communication of the downstream end wall of the horizontal sewage tank, the liquid level meter limits and controls the highest and lowest liquid level in the horizontal sewage tank through the controller, and the liquid level backup associated control is performed in combination with the liquid level detection signal of the high and low bottom medium sensor.

[0030] The bottom between the inner high-position oil cutting pipe and the sunken sludge cavity and the bottom of the sunken sludge cavity of the horizontal sewage tank are respectively connected downward to the oil sludge valve pipe for manual downward sludge cleaning; the center of the two outer convex end heads of the horizontal sewage tank is respectively sealed and fitted with a manhole cover through a manhole flange and a standard fastener, and when the downward sludge cleaning does not work, a person can enter for sludge cleaning.

[0031] The inner low-position feeding pipe and the inner high-position oil cutting pipe are vertical pipes, the upper ends of which are connected to the horizontal pipes extending to both ends, the horizontal pipes are used for feeding and discharging materials through both ends to reduce the disturbance of the layered interface by the liquid flow; the inner low-position feeding pipe and the inner high-position oil cutting pipe are respectively arranged at the front and rear of the upstream section of the horizontal sewage tank, and the sunken sludge cavity is arranged in the middle of the downstream section of the horizontal sewage tank, so as to increase the upward layered path of the contaminated oil and reduce the mixing opportunity of the sludge.

[0032] The oil return pump valve line is an oil return pipe in which the oil return pump, the oil return conveying adjusting valve, the oil pressure gauge, the oil flow meter and the oil return control valve are sequentially arranged and connected to the lower part of the horizontal sewage tank through the inner low-position feeding pipe; the variable flow drainage pump valve line is a drainage pipe in which the sewage pump, the sewage conveying adjusting valve, the sewage pressure gauge, the sewage flow meter and the drainage control valve are sequentially arranged and connected to the lower part of the horizontal sewage tank through the inner high-position feeding pipe, and the variable flow oil return and drainage are performed under the control of the intelligent controller. At least the oil return pump, the oil return conveying adjusting valve, the oil flow meter and the oil return control valve are electrically connected to the intelligent controller, and at least the sewage pump, the sewage conveying adjusting valve, the sewage flow meter and the drainage control valve are electrically connected to the intelligent controller.

[0033] The main working process is as follows: the sewage from the upper process device enters the sewage tank of the sewage collection and distribution unit, and then is subjected to secondary sedimentation in the sewage tank. The control system of the system automatically starts the oil return pump and the water conveying pump according to the detection signal of the oil and water detection sensor of the sewage tank and the set sedimentation time. The specific process is as follows.

[0034] (1) Sewage tank, main functions: a. Collect and temporarily store oil-containing sewage from various storage tanks; b. Provide a secondary settling and separation environment for oil-containing sewage, and a secondary settling environment for impurities; c. Realize oil-water separation through oil-water detection and control; d. When the impurities in the sewage tank accumulate to a set value, the oil sludge medium detection sensor sends a dredging signal.

[0035] Working process: a. Waiting state: water valve is closed, each unit pump is stopped, and other switch valves are in closed state. b. Sewage enters: sewage from the previous process device continuously enters the sewage tank, the tank level rises, and when the tank level reaches the high set value, sewage enters stops; other unit pumps are in stop state, and control valves are in closed state. c. Settling and separation: sewage enters stops, each unit pump stops running, and each unit control valve is closed; the tank level and pressure are in stable state, and sewage is subjected to secondary settling and separation. d. Sewage discharge: when the tank level reaches the high set value and the settling and separation time reaches the set value, the water inlet pump of the previous process device stops, the water inlet valve is closed, the sewage oil conveying unit pump stops, the valve is closed, the sewage discharge unit pump starts, the valve is opened, and the sewage in the tank is continuously discharged. When the tank level decreases to the low set value, the sewage delivery unit changes the flow delivery module to discharge sewage at a small flow rate. When the oil-water detection signal of the oil-water medium detection sensor at the bottom of the sewage tank reaches the set value, the sewage delivery unit pump stops running, and the valve is closed. e. Oil delivery: when the tank level reaches the high set value, and the high and low medium detection sensor signals are both oil signals, and the settling and separation time reaches the set value, the water inlet pump of the previous process device stops, the water inlet valve is closed, the sewage discharge unit pump stops, and the valve is closed. The oil delivery unit pump starts to deliver the oil to the designated container. When the tank level decreases to the low medium detection sensor position, the oil delivery unit pump stops and the valve is closed. f. Oil sludge detection and alarm: during the operation of the sewage tank, the oil sludge medium detection sensor is always in working state, and when the oil sludge in the tank reaches the set value, an alarm signal is automatically sent.

[0036] (2) The sewage discharge unit mainly composed of a variable flow drainage pump valve pipeline, main functions: a. Deliver the sewage in the sewage tank to the tank area sewage pipeline; b. When the oil-water interface or liquid level in the sewage tank decreases to the low medium detection sensor installation position, the pump of the sewage delivery unit automatically reduces the output flow, thereby minimizing the vortex generated by large flow at the oil-water interface in the sewage tank, resulting in incomplete sewage discharge.

[0037] Working process: a. Waiting state: when the liquid level in the sewage tank does not reach the high medium detection sensor installation position, the settling time does not reach the set value, the pump stops, the valve is closed, the sewage discharge unit stops running, and is in a waiting state. b. Discharge state: when the sewage settling time in the tank reaches the set value, the liquid level in the tank is at the high sensor installation position, the inlet pump of the previous process device stops, the inlet valve is closed, the sewage oil delivery unit pump stops, the valve is closed, the sewage discharge unit pump starts, and the sewage in the tank is discharged to the tank area sewage pipeline. c. Small flow discharge: when the oil-water interface or liquid level in the tank drops to the low sensor installation position, the variable flow control module of the sewage discharge unit automatically switches to small flow output. d. Discharge stop: when the oil-water detection signal of the medium detection sensor installed at the bottom of the sewage tank is oil, the pump of the discharge unit automatically stops, and the sewage discharge process ends.

[0038] (3) The sewage oil delivery unit mainly composed of an oil return pump valve pipeline, the main function: delivering the sewage oil in the sewage tank to a designated container. Working process: a. Waiting state: when the high and low medium detection sensor signals of the sewage tank are not all oil signals, the pump stops and the valve is closed. b. Delivery state: when the high and low medium detection sensors of the sewage tank are all oil signals, the pump starts and the valve is opened, and the sewage oil in the tank is delivered to the designated container through the pipeline. c. Delivery stop: when the high and low medium detection sensors of the sewage tank are all non-oil signals, the pump stops and the valve is closed.

[0039] As Figure 1As shown, the system for implementing the method of the present application for realizing the level control and oil-water separation of the fully-closed sewage conveying unit is a closed horizontal long sewage tank 1, the bottom wall of which is provided with an upstream inner low-level feeding pipe 2 and an upstream inner high-level oil cutting pipe 3 and a downstream sunken sludge chamber 4 along the long axis in sequence, the side wall of the horizontal long sewage tank 1 is provided with a high-level medium sensor 51 higher than the inlet of the inner high-level oil cutting pipe 3 in the region between the inner high-level oil cutting pipe 3 and the sunken sludge chamber 4, a low-level medium sensor 52 and a bottom-level medium sensor 53 are respectively arranged at least at the height of the inlet of the inner high-level oil cutting pipe 3 and the height of the outlet of the inner low-level feeding pipe 2, and a sludge medium detection sensor 54 is arranged on the side wall of the sunken sludge chamber 4; the top of the horizontal long sewage tank 1 is connected to a pressure gauge 60 and a pressure transducer sensor 6 of an electrically connected intelligent controller, the downstream end of the horizontal long sewage tank 1 is connected to a liquid level meter 61 of the electrically connected intelligent controller, the inner low-level feeding pipe 2 is connected downward to a water cutting pipe line of a storage tank, the inner high-level oil cutting pipe 3 is connected downward to an oil return pump valve pipe line of the storage tank, and the sunken sludge chamber 4 is connected downward to an oil sludge discharge valve pipe 70 and a variable flow drainage pump valve pipe line connected to a sewage storage facility; when the sludge medium detection sensor 54 detects sludge, a dredging signal is sent out through the intelligent controller. The inner low-level feeding pipe feeds within the set gas phase pressure and liquid level range through the water cutting pipe line connected to the storage tank, the inner high-level oil cutting pipe returns oil when the detection signals of the high-level and low-level medium sensors are both oil through the oil return pump valve pipe line connected to the storage tank, the sunken sludge chamber is connected to the oil sludge discharge valve pipe and the variable flow drainage pump valve pipe line connected to the sewage storage facility, and when the detection signals of the high-level and low-level medium sensors are both water, large flow drainage is performed, and small flow drainage is performed within the water level range of the low bottom-level medium sensor; when the sludge medium detection sensor detects sludge, a dredging signal is sent out through the intelligent controller. The height of the inner high-level oil cutting pipe is about 3 / 4 of the height of the inner cavity of the horizontal long sewage tank, and the height of the inner low-level feeding pipe is 5-9% of the height of the inner cavity of the horizontal long sewage tank. The method has the advantages of easy separation of oil and sludge and good water cutting and oil return quality.

[0040] The safety valve 62 and the pressure relief valve pipe 71 are connected to the upstream side of the top of the horizontal sewage tank 1. The sludge blowing valve pipe 72, which is lower than the inner low-level feeding pipe, is connected to the upstream end wall of the horizontal sewage tank 1. The pressurizing pump valve pipe, which delivers pressure gas to the sludge blowing valve pipe 72, is connected to the top of the horizontal sewage tank 1. The pressurizing pump valve pipe, which is connected to the top of the horizontal sewage tank and the sludge blowing valve pipe, blows pressure into the horizontal sewage tank through the sludge blowing valve pipe to blow the sludge at the bottom of the horizontal sewage tank to the downstream direction where the sunken oil sludge cavity is located. The sludge inspection window valve pipe 73, which is connected to the bottom of the horizontal sewage tank 1 downstream of the inner low-level feeding pipe 2, is opened to blow the sludge at the bottom of the horizontal sewage tank to the downstream side when the sludge is found in the sludge inspection window. After the blowing, the lower discharge valve of the sludge inspection window valve pipe 73 is opened to discharge the sludge in the sludge inspection window, and then the lower discharge valve is closed. The safety valve 62 and the two spaced parallel pressure relief valve pipes 71, as well as the vent valve pipe 74 and the standby valve pipe 75, are connected to the top of the horizontal sewage tank 1 from the upstream end to the downstream end in sequence. The pressure gauge 60, the pressure variable transmission sensor 60, and the two spaced parallel standby valve pipes 75 are also connected to the top of the horizontal sewage tank 1. The two spaced parallel pressure relief valve pipes 71 and the vent valve pipe 74 are jointly connected to the vent tail pipe 79. The standby valve pipe of the top of the horizontal sewage tank is connected to the pressurizing pump valve pipe. The pressure gauge and the pressure variable transmission sensor are arranged in the middle of the top of the horizontal sewage tank between the upstream and the downstream, which is beneficial to timely and comprehensive sensing of the gas phase pressure change in the tank.

[0041] The temperature gauge 63 and the temperature variable transmission sensor 64 of the electrically connected intelligent controller, which have a height at least equal to the inner low-level feeding pipe 2, are arranged in the area close to the inner high-level oil cutting pipe 3 between the inner high-level oil cutting pipe 3 and the bottom medium sensor 53 of the side wall of the horizontal sewage tank 1. The intelligent controller controls the oil return and drainage according to the temperature: low temperature controls small flow for oil return and drainage, and high temperature controls large flow for oil return and drainage. The liquid level meter 61 of the electrically connected intelligent controller is arranged on the lower end of the downstream wall of the horizontal sewage tank 1. The liquid level meter 61 controls the highest and lowest liquid level in the horizontal sewage tank 1 through the controller, and performs backup associated control of the liquid level in combination with the liquid level detection signals of the high-level medium sensor 51, the low-level medium sensor 52, and the bottom medium sensor 53.

[0042] The oil sludge discharge valve pipe 70, which is used for manual discharge and dredging, is connected to the bottom of the horizontal sewage tank 1 between the inner high-level oil cutting pipe 3 and the sunken oil sludge cavity 4, and to the bottom of the sunken oil sludge cavity 4. The manhole cover 11 is sealed and fitted to the center of the two outer convex ends of the horizontal sewage tank 1 through the manhole flange 10 and the standard fastener. When the manual discharge and dredging is ineffective, a person can enter for dredging.

[0043] The inner low-position feeding pipe 2 and the inner high-position cutting oil pipe 3 are vertical pipes, the upper ends of which are communicated to the symmetrically extended horizontal pipes, the liquid in and out of which is reduced to disturb the interface of the stratified layer; the inner low-position feeding pipe 2 and the inner high-position cutting oil pipe 3 are respectively located at the front and rear of the upstream section of the horizontal sewage tank 1, and the sinking sludge cavity 4 is located at the middle of the downstream section of the horizontal sewage tank 1, so as to increase the stratified path of the dirty oil and reduce the mixing opportunity of the sludge.

[0044] The oil return pump valve line is the oil return pipe 80 of the inner low-position feeding pipe 2 which is communicated to the lower part of the horizontal sewage tank 1 and sequentially provided with the manual dirty oil valve 8, the dirty oil pump 81, the dirty oil delivery adjusting valve 82, the manual dirty oil valve 8, the dirty oil pressure gauge 83, the dirty oil flow meter 84 and the oil return control valve 85, and the manual dirty oil valve 8; the variable flow drainage pump valve line is the drainage pipe 90 of the inner high-position feeding pipe 3 which is communicated to the lower part of the horizontal sewage tank 1 and sequentially provided with the manual sewage valve 9, the sewage pump 91, the sewage delivery adjusting valve 92, the manual sewage valve 9, the sewage pressure gauge 93, the sewage flow meter 94 and the drainage control valve 95, and the manual sewage valve 9, and the variable flow oil return and drainage are carried out under the control of the intelligent controller. At least the dirty oil pump, the dirty oil delivery adjusting valve, the dirty oil flow meter and the oil return control valve are electrically connected to the intelligent controller, and at least the sewage pump, the sewage delivery adjusting valve, the sewage flow meter and the drainage control valve are electrically connected to the intelligent controller.

[0045] In summary, the method and system for the boundary control and the oil-water separation of the sewage fully-closed conveying unit have the advantages of easy separation of the oil and the sludge, real-time online detection, accurate oil-water separation, self-adaptive sewage closed conveying, and good quality and effect of the cutting water and oil return.

Claims

1. A method for realizing the interface control and oil-water separation of a full-closed sewage conveying unit, characterized in that The bottom wall of the closed horizontal sewage tank is sequentially provided with an inner low-position feed pipe and an inner high-position oil cutting pipe and a sunken sludge cavity along the long axis, the side wall of the horizontal sewage tank is provided with a high-position medium sensor higher than the inlet of the inner high-position oil cutting pipe in the region between the inner high-position oil cutting pipe and the sunken sludge cavity, a low-position medium sensor and a bottom-position medium sensor are respectively arranged at least at the height of the inlet of the inner high-position oil cutting pipe and the height of the outlet of the inner low-position feed pipe, and a sludge medium detection sensor is arranged on the side wall of the sunken sludge cavity; the top of the horizontal sewage tank is connected with a pressure transmitter sensor of an electrically connected intelligent controller, the downstream end of the horizontal sewage tank is connected with a liquid level meter of the electrically connected intelligent controller, the inner low-position feed pipe feeds in the set gas phase pressure and liquid level range through a water cutting pipeline connected with the storage tank, the inner high-position oil cutting pipe returns oil when the detection signals of the high-position medium sensor and the low-position medium sensor are both oil through an oil return pump valve pipeline connected with the storage tank, the sunken sludge cavity is connected with a sludge discharge valve pipeline and a variable flow drainage pump valve pipeline connected with a sewage storage facility, when the detection signals of the high-position medium sensor and the low-position medium sensor are both water, large flow drainage is performed, small flow drainage is performed in the water level range of the low-position medium sensor and the bottom-position medium sensor, and when the sludge medium detection sensor detects sludge, a dredging signal is sent through the intelligent controller; The pressurizing pump valve pipeline connected with the top of the horizontal sewage tank blows gas to the inside of the horizontal sewage tank through a sludge blowing valve pipeline to blow the sludge at the bottom of the horizontal sewage tank to the downstream direction where the sunken sludge cavity is located.

2. The method for realizing the boundary position control and oil-water separation of the full-closed sewage conveying unit according to claim 1, characterized in that The top of the horizontal sewage tank is connected with a safety valve and a pressure relief valve pipeline on the upstream side, and the horizontal sewage tank is connected with a sludge blowing valve pipeline lower than the inlet of the inner low-position feed pipe on the end wall on the upstream side.

3. The method for realizing the boundary position control and oil-water separation of the full-closed sewage conveying unit according to claim 2, characterized in that The bottom of the horizontal sewage tank is connected with a sludge visual inspection window valve pipeline downward on the downstream side of the inner low-position feed pipe, when sludge is found to enter the sludge visual inspection window, the sludge at the bottom of the horizontal sewage tank is blown to the downstream side through the pressurizing pump valve pipeline, after blowing, the lower discharge valve of the sludge visual inspection window valve pipeline is opened to empty the sludge in the sludge visual inspection window, and then the lower discharge valve is closed.

4. The method for realizing the boundary position control and oil-water separation of the full-closed sewage conveying unit according to claim 1, characterized in that The side wall of the horizontal sewage tank is provided with a temperature meter with a height at least flush with the inner low-position feed pipe and a temperature transmitter sensor of an electrically connected intelligent controller in the region between the inner high-position oil cutting pipe and the bottom-position medium sensor, the intelligent controller controls the oil return and drainage according to the temperature: small flow control is performed when the temperature is low, and large flow control is performed when the temperature is high; the end wall of the horizontal sewage tank is connected with a liquid level meter of an electrically connected intelligent controller at the top and the bottom, the liquid level meter controls the highest and lowest liquid levels in the horizontal sewage tank through the controller, and the liquid level backup associated control is performed in combination with the liquid level detection signals of the high-position medium sensor, the low-position medium sensor and the bottom-position medium sensor.

5. The method for realizing the boundary position control and oil-water separation of the full-closed sewage conveying unit according to claim 1, characterized in that The bottom of the horizontal sewage tank is connected with a sludge discharge valve pipeline downward between the inner high-position oil cutting pipe and the sunken sludge cavity and at the bottom of the sunken sludge cavity, which is used for manual sludge discharge; the centers of the two outer convex ends of the horizontal sewage tank are respectively sealed and fitted with manhole covers through manhole flanges and standard fasteners, which are used for manual sludge discharge when manual sludge discharge is not effective.

6. The method for realizing the boundary position control and oil-water separation of the full-closed sewage conveying unit according to claim 1, characterized in that The inner low-position feed pipe and the inner high-position oil cutting pipe are vertical pipes connected to horizontal pipes extending to both ends, and the horizontal pipes are used to reduce the disturbance of the liquid flow to the stratified interface by feeding and discharging from both ends; the inner low-position feed pipe and the inner high-position oil cutting pipe are respectively located at the front and rear of the upstream section of the horizontal sewage tank, and the sunken sludge cavity is located in the middle of the downstream section of the horizontal sewage tank, so as to increase the stratified path of the contaminated oil and reduce the mixing opportunity of the sludge.

7. The method for realizing the boundary position control and oil-water separation of the full-closed sewage conveying unit according to claim 1, characterized in that The oil return pump valve line is an oil return pipe connected from the inner low-position feed pipe to the lower part of the horizontal sewage tank, and sequentially provided with a contaminated oil pump, an oil return conveying adjusting valve, a contaminated oil pressure gauge, a contaminated oil flow meter and an oil return control valve; the variable flow drainage pump valve line is a drainage pipe connected from the inner high-position feed pipe to the lower part of the horizontal sewage tank, and sequentially provided with a sewage pump, a sewage conveying adjusting valve, a sewage pressure gauge, a sewage flow meter and a drainage control valve, and the variable flow oil return and drainage are performed under the control of the intelligent controller.

8. A system for implementing the method of claim 1 for implementing the boundary control and oil-water separation of a full-closed sewage conveying unit, characterized in that, The bottom wall of the closed horizontal long sewage tank is sequentially provided with the inner low-position feed pipe, the inner high-position oil cutting pipe and the sunken sludge cavity along the long axis at intervals, the side wall of the horizontal sewage tank is provided with a high-position medium sensor higher than the inlet of the inner high-position oil cutting pipe in the region between the inner high-position oil cutting pipe and the sunken sludge cavity, a low-position medium sensor and a bottom-position medium sensor are respectively arranged at least at the height of the inlet of the inner high-position oil cutting pipe and the height of the outlet of the inner low-position feed pipe, and a sludge medium detection sensor is arranged on the side wall of the sunken sludge cavity; the top of the horizontal sewage tank is connected to a pressure transmitter sensor of the electrically connected intelligent controller, the downstream end of the horizontal sewage tank is connected to a liquid level meter of the electrically connected intelligent controller, the inner low-position feed pipe is connected downward to a water cutting pipe line of a storage tank, the inner high-position oil cutting pipe is connected downward to an oil return pump valve line of the storage tank, and the sunken sludge cavity is connected to a sludge discharge valve pipe and a variable flow drainage pump valve line connected to a sewage storage facility; when the sludge medium detection sensor detects sludge, a dredging signal is sent through the intelligent controller.

9. The system of claim 8, wherein A safety valve and a pressure relief valve pipe are connected to the top upstream side of the horizontal sewage tank, and a sludge blowing valve pipe lower than the inlet of the inner low-position feed pipe is connected to the upstream end wall of the horizontal sewage tank, and a pressurizing pump valve pipe for conveying pressure gas to the sludge blowing valve pipe is connected to the top of the horizontal sewage tank.

10. The system of claim 9, wherein The inner low-position feed pipe and the inner high-position oil cutting pipe are vertical pipes connected to horizontal pipes extending to both ends, and the inner low-position feed pipe and the inner high-position oil cutting pipe are respectively located at the front and rear of the upstream section of the horizontal sewage tank, and the sunken sludge cavity is located in the middle of the downstream section of the horizontal sewage tank.

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