Shutdown airtight treatment method for electric desalting tank

Abstract

The invention relates to the technical field of petrochemical equipment maintenance process treatment, and particularly discloses a shutdown airtight treatment method for an electric desalting tank. The device comprises an electric desalting tank body, and a crude oil feeding pipeline, a crude oil outlet pipeline, a safety valve overline, a close-packed pipeline, a low-pressure steam pipeline and a backwashing water supply flow which are connected with the body, the crude oil feeding pipeline is provided with a crude oil feeding valve and a raw material bypass valve connected in parallel, and a water injection flow with a water injection valve is branched; the tank top is provided with an outlet collector and a safety valve overline with a tank top safety valve overline valve, the tank bottom is provided with a close-packed pipeline with a drain valve and a low-pressure steam pipeline with a tank bottom low-pressure steam valve, and a backwashing distributor communicated with a backwashing water supply flow with a backwashing water supply valve is arranged in the tank. According to the device, by optimizing the original technological process, segmented replacement and recovery, fully-closed discharge and rapid backflushing cooling are achieved, additional equipment does not need to be additionally arranged, the operation difficulty and cost are reduced, and the shutdown period is shortened.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of petroleum chemical equipment maintenance process, in particular to a method for closed treatment of electric desalting tank shutdown. BACKGROUND

[0002] In the petroleum chemical industry, the electric desalting tank is the core equipment for crude oil pretreatment, and its single tank volume is usually proportional to the processing capacity of the device, resulting in a large amount of oil stored in the tank. Since the electric desalting tank contains crude oil, which has complex components, many impurities, high viscosity and strong adhesion, the shutdown treatment process of the electric desalting tank is relatively complex, and the treatment effect is often unsatisfactory.

[0003] In the traditional electric desalting tank shutdown treatment method, the following problems exist:

[0004] First, the oil withdrawal and cooling time is long. The traditional cooling method is cycle cooling or natural cooling, and the cooling period is as long as about 24 hours. The overall treatment period of a single tank is about 72 hours, which seriously affects the maintenance efficiency.

[0005] Second, there is a lot of residual oil in the dead angle. Crude oil is easily left in areas such as the collector at the top of the tank and the inlet and outlet pipe sections of the safety valve, and it is difficult to completely remove.

[0006] Third, the site emission odor is large. Oil and gas are directly discharged on site, which not only causes environmental pollution, but also poses a safety hazard.

[0007] Fourth, the cost of equipment configuration is high. An independent oil withdrawal pump and the corresponding process need to be additionally provided to achieve oil withdrawal.

[0008] Fifth, the operation time is not flexible. The treatment process needs to be synchronized with the shutdown of the device, and cannot be carried out in advance, further prolonging the overall shutdown period of the device.

[0009] The above traditional treatment method cannot meet the requirements of green environmental protection, safety and efficiency of shutdown treatment, therefore, a method for electric desalting tank shutdown treatment without additional equipment, which can achieve efficient recovery and full-closed discharge, is needed to solve the above problems. SUMMARY

[0010] In view of the deficiencies of the prior art, the present application provides a method for closed treatment of electric desalting tank shutdown, which solves the technical problems of long oil withdrawal and cooling time, large amount of residual oil in dead angle, large odor emission on site, need to provide independent oil withdrawal pump and other additional equipment, and poor flexibility of operation synchronized with device shutdown.

[0011] To achieve the above purpose, the present application realizes the following technical solutions:

[0012] The application discloses a kind of electric desalter tank shutdown sealing treatment methods, including electric desalter tank body, crude oil feed pipeline, crude oil outlet pipeline, safety valve cross line and dense pipeline;

[0013] Crude oil feed pipeline is equipped with crude oil feed valve and raw material bypass valve, raw material bypass valve is connected in parallel at the two ends of crude oil feed valve, and water injection process for injecting water source is further provided on crude oil feed pipeline, and water injection valve is provided on water injection process;

[0014] The tank top of the electric desalter tank body is provided with an outlet collector, which is in communication with one end of the crude oil outlet pipeline. The other end of the crude oil outlet pipeline is used to connect a production refining system, and a crude oil outlet valve is provided on the crude oil outlet pipeline.

[0015] One end of the safety valve cross line is in communication with the tank top of the electric desalter tank body, and the other end is used to connect a flash tower / primary distillation tower and a flare gas system, respectively. A tank top safety valve cross line valve is provided on the safety valve cross line. The tank top of the electric desalter tank body is also provided with a safety valve cooperating with the safety valve cross line.

[0016] One end of the dense pipeline is in communication with the tank bottom of the electric desalter tank body, and the other end is used to connect a sewage treatment field. A drain valve is provided on the dense pipeline.

[0017] Preferably, a low-pressure steam pipeline is further included. One end of the low-pressure steam pipeline is in communication with the tank bottom of the electric desalter tank body, and the other end is used to connect a low-pressure steam source. A tank bottom low-pressure steam valve is provided on the low-pressure steam pipeline.

[0018] Preferably, a backwash water supply process and a backwash distributor are further included. The backwash distributor is arranged inside the electric desalter tank body. One end of the backwash water supply process is in communication with the backwash distributor, and the other end is used to connect a water source. A backwash water supply valve is provided on the backwash water supply process.

[0019] Preferably, a nitrogen gas pipeline is further included. One end of the nitrogen gas pipeline is in communication with the tank top of the electric desalter tank body, and the other end is used to connect a nitrogen gas source. A tank top nitrogen gas valve is provided on the nitrogen gas pipeline.

[0020] Preferably, the pipe section in the safety valve cross line that is in communication with the flash tower / primary distillation tower is not provided with internal components, and the pipe section in the safety valve cross line that is in communication with the flare gas system is also used to connect a fractionation gas phase pipeline.

[0021] Preferably, the backwash distributor is in the form of a ring-shaped pipe structure. A plurality of spray holes are formed in the pipe wall of the ring-shaped pipe, and the plurality of spray holes are uniformly distributed along the circumference of the ring-shaped pipe.

[0022] Preferably, a one-way valve is arranged on the pipe section of the crude oil outlet pipeline close to the production refining system, the one-way valve is arranged to be open from the electric desalting tank body to the production refining system, and a filter is arranged on the pipe section of the dense pipeline close to the sewage treatment field, and the filter has a filtering accuracy of 50-100 meshes.

[0023] Preferably, the electric desalting tank shutdown sealed treatment method comprises the following steps.

[0024] S1: independently cutting off and recovering the main oil product, opening the raw material bypass valve, closing the crude oil feeding valve, keeping the crude oil outlet valve open, opening the water injection valve to inject water into the tank to lift the oil-water interface, collecting the main oil product through the tank top outlet collector, and then recycling the main oil product to the production refining system through the crude oil outlet pipeline.

[0025] S2: residual oil product replacement and recovery, closing the crude oil outlet valve, opening the tank top safety valve cross line valve, continuing to inject water through the water injection valve, replacing the residual oil product between the tank top outlet collector and the tank top, and the safety valve inlet and outlet pipe section, recycling the residual oil product to the flash tower / primary distillation tower through the safety valve cross line, and then closing the tank top safety valve cross line valve and the water injection valve.

[0026] S3: sewage discharge, opening the drainage valve, and using the residual pressure in the tank to transport the sewage to the sewage treatment field through the dense pipeline; if the residual pressure is insufficient, opening the tank top nitrogen valve to pressurize by nitrogen, until the residual sewage interface in the tank is 15%-20% of the tank capacity, and then closing the tank top nitrogen valve and the drainage valve.

[0027] S4: tank boiling and oil gas recovery, opening the tank bottom low-pressure steam valve to introduce low-pressure steam to boil the tank, and opening the tank top safety valve cross line valve to introduce the oil gas and water vapor generated by boiling the tank into the flare gas recovery system through the safety valve cross line; after boiling the tank, closing the tank bottom low-pressure steam valve, and then closing the tank top safety valve cross line valve after the residual oil gas is discharged.

[0028] S5: backflushing, cooling and discharging the mixture, opening the backflushing water supply valve, introducing backflushing water into the tank through the backflushing distributor for cooling and stirring; after the temperature in the tank is reduced to a preset value, closing the backflushing water supply valve, opening the drainage valve to transport the oil-water mixture in the tank to the sewage treatment field through the dense pipeline, and then closing the drainage valve to complete the treatment.

[0029] Compared with the prior art, the present application has the following beneficial effects:

[0030] The oil recovery rate is significantly improved: the device uses the segmented replacement structure of water injection to lift oil + safety valve cross line secondary replacement to improve the effective recovery rate of oil, maximizes the production value of raw materials, and reduces resource waste.

[0031] Achieving fully enclosed and environmentally friendly emissions: During the oil withdrawal stage, the crude oil outlet pipeline and safety valve are used to achieve closed-loop oil recovery. During the water withdrawal stage, the wastewater is transported to the wastewater treatment plant through a closed-loop pipeline. During the tank boiling stage, the oil and water vapor are introduced into the flare gas recovery system through a safety valve. This completely changes the traditional on-site emission method, eliminates on-site odors, prevents VOCs from escaping, and meets green and environmental protection requirements.

[0032] The workload of tank cleaning is greatly reduced: Since this device can thoroughly remove residual oil and sludge from the tank through segmented replacement and steam boiling, the workload of cleaning a single tank is reduced, which reduces the labor intensity and cost of subsequent tank cleaning operations.

[0033] Flexible operation time and no interruption of unit downtime: The electric desalination tank can be independently disconnected for replacement operation in advance through the raw material bypass valve, without having to be carried out at the same time as the unit shutdown, thus avoiding the extension of the unit downtime and significantly improving the overall maintenance efficiency.

[0034] No additional equipment required, reducing costs: This device only optimizes the valve and pipeline connections based on the original process flow of the electric desalting tank, eliminating the need for the independent oil return pump and additional processes required by traditional processing methods, thus reducing equipment investment and maintenance costs.

[0035] Highly efficient and rapid cooling, shortening the processing cycle: After steam boiling, backwash water is introduced through the backwash distributor for rapid cooling and stirring, shortening the cooling cycle and the overall processing cycle of a single tank, greatly improving the efficiency of downtime processing. Attached Figure Description

[0036] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0037] Figure 1 This is a diagram showing the overall architecture of the system in this invention.

[0038] Legend: 1. Crude oil feed valve; 2. Crude oil outlet valve; 3. Raw material bypass valve; 4. Water injection valve; 5. Tank top safety valve / cross-line valve; 6. Tank top nitrogen valve; 7. Drain valve; 8. Tank bottom low-pressure steam valve; 9. Backwash water supply valve; 10. Safety valve; 11. Outlet collector; 12. Backwash distributor. Detailed Implementation

[0039] This application provides a method for the closed-loop treatment of electric desalting tank shutdown, which effectively solves the technical problems of long oil removal and cooling time, large amount of residual oil in dead corners, strong on-site odor, need for additional equipment such as independent oil removal pumps, and poor flexibility due to the need for the operation to be synchronized with the shutdown of the unit in the traditional electric desalting tank shutdown treatment.

[0040] Example

[0041] like Figure 1 As shown, the overall technical solution in this application embodiment is as follows:

[0042] To address the problems existing in the current technology, such as Figure 1 As shown, this invention provides a method for the closed-loop treatment of an electrostatic desalting tank after shutdown, applicable to the closed-loop treatment operations of electrostatic desalting tanks in the petrochemical industry. Its core is to optimize the existing pipeline and valve connection structure to achieve efficient oil recovery, fully closed discharge, and rapid cooling. The following detailed description of the specific operation process further illustrates this. Figure 1 In the diagram, A represents crude oil export, B represents crude oil import, C represents water injection, D represents nitrogen, E represents flare gas system, F represents drainage to the sewage treatment plant, G represents low-pressure steam, and H represents backwash water.

[0043] First, the core structural components of the shut-down closed treatment system for the electric desalting tank include: the electric desalting tank body, crude oil feed pipeline, crude oil outlet pipeline, safety valve crossover line, dense pipeline, nitrogen pipeline, low-pressure steam pipeline, and backwash water supply process connected to the body;

[0044] Among them, crude oil feed valve 1 is connected in series on the crude oil feed pipeline, and raw material bypass valve 3 is connected in parallel at both ends of crude oil feed valve 1. A water injection process is also branched on the crude oil feed pipeline, and a water injection valve 4 is connected in series on the water injection process.

[0045] An outlet collector 11 is fixedly installed on the top of the electric desalting tank body. The discharge end of the outlet collector 11 is connected to one end of the crude oil outlet pipeline, and the other end of the crude oil outlet pipeline is connected to the production refining system. A crude oil outlet valve 2 is connected in series on the crude oil outlet pipeline.

[0046] The top of the electric desalting tank is also equipped with a safety valve 10. The safety valve 10 is bypassed by a safety valve cross-line. A safety valve cross-line valve 5 is connected in series on the safety valve cross-line. One end of the safety valve cross-line is connected to the top of the tank, and the other end is connected to the flash tower / primary distillation tower and the flare gas system respectively.

[0047] One end of the densely packed pipeline is connected to the bottom of the electric desalination tank body, and the other end is connected to the sewage treatment plant. A drain valve 7 is connected in series on the densely packed pipeline.

[0048] One end of the nitrogen pipeline is connected to the top of the tank, and the other end is connected to the nitrogen source. A nitrogen valve 6 for the top of the tank is connected in series on the nitrogen pipeline.

[0049] One end of the low-pressure steam pipeline is connected to the bottom of the tank, and the other end is connected to the low-pressure steam source. A low-pressure steam valve 8 for the bottom of the tank is connected in series on the low-pressure steam pipeline.

[0050] One end of the backwash water supply process is connected to the water source, and the other end extends into the tank and is connected to the backwash distributor 12. The backwash distributor 12 is fixed in the lower part of the tank, and a backwash water supply valve 9 is connected in series in the backwash water supply process.

[0051] Oil removal stage:

[0052] When the electrostatic desalting tank needs to be shut down, an independent disconnection operation is first performed: open the raw material bypass valve 3 to allow crude oil to be transported to the downstream system through the raw material bypass valve 3, and simultaneously close the crude oil feed valve 1 to cut off the feed of crude oil to the electrostatic desalting tank body; keep the crude oil outlet valve 2 in the open state to complete the disconnection of the electrostatic desalting tank from the main process of the unit. Then open the water injection valve 4 to inject demineralized water (or other water sources selected according to the actual unit) into the electrostatic desalting tank body through the water injection process on the crude oil feed pipeline. Utilize the density difference between oil and water to cause the medium in the tank to naturally stratify (water at the bottom and oil at the top). As the amount of water injected increases, the oil-water interface in the tank gradually rises. The oil stored in the upper part of the tank is collected through the tank top outlet collector 11 and then transported to the production refining system through the crude oil outlet pipeline and the opened crude oil outlet valve 2 to achieve the recovery of the main oil products. After the main oil product recovery is completed, close the crude oil outlet valve 2, open the tank top safety valve crossover valve 5, and continue to inject water through the water injection valve 4 to raise the boundary level. Replace the residual crude oil between the tank top outlet collector 11 and the tank top, as well as in the inlet and outlet pipe sections of the safety valve 10, to the safety valve crossover. The residual crude oil is then transported through the safety valve crossover to the flash distillation tower / primary distillation tower for closed-loop recovery, completely eliminating dead zone residue. After the residual crude oil replacement is completed, close the tank top safety valve crossover valve 5 and the water injection valve 4.

[0053] Receding water stage:

[0054] After the oil removal operation is completed, open the drain valve 7 on the dense pipeline and use the residual pressure in the desalination tank to transport the water in the tank to the sewage treatment plant through the dense pipeline. If the residual pressure in the tank is insufficient, causing the drainage speed to slow down or stop, open the nitrogen valve 6 on the top of the tank and fill the tank with nitrogen to increase the pressure in the tank until the residual sewage level in the tank drops to 15%~20% (relative to the tank volume). Then close the nitrogen valve 6 on the top of the tank and the drain valve 7.

[0055] Boiling and cooling stages:

[0056] After the dewatering is completed, open the low-pressure steam valve 8 at the bottom of the tank to introduce 1.0 MPa, 200°C low-pressure saturated steam into the desalination tank. Simultaneously, open the safety valve crossover valve 5 at the top of the tank. The steam heats and removes the oil stains adhering to the inner wall and internal parts of the tank, and boils and dissolves the oil sludge and scale deposited at the bottom of the tank, forming a transportable oil-water mixture. The oil and water vapor generated during the boiling process are incorporated into the fractionated gas phase through the safety valve crossover valve and then transported to the flare gas recovery system to avoid on-site emissions. The boiling operation continues until the oil stains and sludge are fully dissolved. Then, close the low-pressure steam valve 8 at the bottom of the tank, and keep the safety valve crossover valve 5 at the top of the tank open for a period of time to discharge residual oil and gas. Subsequently, close the safety valve crossover valve 5 at the top of the tank and open the backwash water supply valve 9 to deliver backwash water into the tank through the backwash water supply process. The backwash water is evenly sprayed into the tank through the backwash distributor 12 to quickly cool and stir the medium inside the tank, so that the undissolved oil sludge and water are fully mixed. When the temperature of the wastewater in the tank drops to about 50°C, close the backwash water supply valve 9 and open the drain valve 7 again to transport the oil-water mixture in the tank to the wastewater treatment plant for subsequent separation treatment through the dense pipeline. After the oil-water mixture is discharged, close the drain valve 7 to complete the shutdown and sealing treatment of the electric desalination tank.

[0057] This method, through the combination of the above structure and operation, can achieve high recovery rate, fully enclosed and efficient treatment during the shutdown process of the electric desalination tank without the need for additional equipment, effectively solving the pain points of traditional treatment methods.

[0058] This method is based on the optimization of existing processes and does not require the addition of extra core equipment. It achieves efficient oil recovery, fully enclosed discharge, and rapid treatment through a three-stage closed-loop operation of oil removal, water removal, and tank boiling and cooling. The specific steps are as follows:

[0059] I. Preliminary Preparations:

[0060] Confirm that the desalting tank has stopped feeding and the pressure inside the tank has dropped to atmospheric pressure. Record the initial liquid level and temperature data inside the tank.

[0061] Check the status of all related pipeline valves: ensure that the crude oil outlet pipeline check valve (direction pointing to the production and refining system), the close-packed pipeline filter (50-100 mesh) are in good condition, and that the nitrogen source, low-pressure steam source (1.0MPa, 200℃), and backwash water source are ready.

[0062] Confirm that the flash distillation tower / primary distillation tower, flare gas system, and wastewater treatment plant are in receiving mode and that communication is unimpeded.

[0063] II. Oil Removal Stage (Segmented Replacement and Recovery of Oil, Elimination of Dead Zone Residue):

[0064] Step 1: Independently disconnect the electrostatic desalting tank:

[0065] Open raw material bypass valve 3 to allow crude oil to be transported to downstream systems through the bypass pipeline, ensuring continuous production.

[0066] Close crude oil feed valve 1 to disconnect the electric desalting tank from the main feed process.

[0067] Keep crude oil outlet valve 2 open to ensure that the oil in the tank can be recovered to the production and refining system through the outlet pipeline, thus completing the independent disconnection of the tank and the main process of the unit.

[0068] Step 2: Inject water to top up the oil and recover the main oil products:

[0069] Open water injection valve 4 and inject demineralized water (or water source designated by the unit) into the tank through the water injection process on the crude oil feed pipeline.

[0070] The oil-water density difference (water at the bottom and oil at the top) is used to achieve natural stratification, and water is continuously injected to raise the oil-water interface inside the tank.

[0071] The oil stored in the upper part of the tank is collected by the tank top outlet collector 11 and then transported to the production refining system through the crude oil outlet pipeline and the opened crude oil outlet valve 2 to recover 85% to 90% of the main oil products.

[0072] Observe the flow rate of the outlet pipeline. When the flow rate drops significantly, it is determined that the main oil product has been recovered.

[0073] Step 3: Secondary replacement to recover residual oil:

[0074] Close crude oil outlet valve 2 and open tank top safety valve cross-line valve 5.

[0075] Continue to inject water through water injection valve 4 to further raise the oil-water interface and replace residual crude oil in dead zones such as between tank top outlet collector 11 and tank top, and inlet and outlet pipe sections of safety valve 10.

[0076] The residual crude oil is transported across the line to the flash distillation tower / primary distillation tower via a safety valve for closed-loop recovery, ensuring a total oil recovery rate of 95% to 97%.

[0077] When no oil flows out of the safety valve cross-line, close the safety valve cross-line valve 5 and water injection valve 4 on the top of the tank, and the oil return phase ends.

[0078] III. Drainage Stage (Discharge wastewater from the sealed tank to ensure conditions for subsequent tank boiling):

[0079] Step 1: Drain water using residual pressure:

[0080] Open the drain valve 7 on the dense pipeline and use the residual pressure inside the tank to transport the water in the tank to the sewage treatment plant through the dense pipeline.

[0081] Continuously monitor the drainage flow rate and liquid level in the tank, and record pressure changes during the drainage process.

[0082] Step 2: Nitrogen pressurization to assist drainage:

[0083] When the drainage rate slows down significantly or stops, it is determined that the residual pressure inside the tank is insufficient.

[0084] Open nitrogen valve 6 on the top of the tank to fill the tank with nitrogen and increase the pressure to assist in the discharge of sewage.

[0085] When the level of remaining wastewater in the tank drops to 15%~20% of the tank capacity, close the nitrogen valve 6 and drain valve 7 on the top of the tank, and the effluent discharge stage ends.

[0086] IV. Boiling and Cooling Stage (Removal of oil and sludge, rapid cooling, and completion of sealing):

[0087] Step 1: Dissolve the sludge in a steam bath:

[0088] Open the low-pressure steam valve 8 at the bottom of the tank and introduce low-pressure saturated steam at 1.0 MPa and 200°C into the tank.

[0089] At the same time, the safety valve 5 on the top of the tank is opened, and the oil and water vapor generated during the boiling process are connected to the fractionated gas phase through the safety valve and finally delivered to the flare gas recovery system to prevent VOCs from escaping.

[0090] Steam continuously heats the oil stains adhering to the inner wall and internal parts of the tank, and boils and dissolves the oil sludge and grease deposited at the bottom of the tank, forming a transportable oil-water mixture. The boiling time is adjusted according to the amount of oil sludge in the tank (usually 4~6 hours).

[0091] Step 2: Backwash for rapid cooling and stirring:

[0092] Close the low-pressure steam valve 8 at the bottom of the tank, and keep the safety valve crossover valve 5 at the top of the tank open for 30 minutes to discharge the residual oil and gas in the tank.

[0093] Close the safety valve 5 on the top of the tank and open the backwash water supply valve 9 to supply backwash water into the tank through the backwash water supply process.

[0094] Backwash water is evenly sprayed through the backwash distributor 12 (with spray holes evenly distributed on the pipe wall) in the annular pipe structure inside the tank, so as to achieve rapid cooling and stirring of the medium inside the tank, and to fully mix the undissolved sludge with water.

[0095] Step 3: Drain the oil-water mixture:

[0096] Continuously monitor the temperature inside the tank. When the wastewater temperature drops to around 50°C, close the backwash water supply valve 9.

[0097] Open drain valve 7 again to transport the oil-water mixture in the tank to the wastewater treatment plant for further separation and treatment through the dense pipeline.

[0098] After the oil-water mixture has been completely drained, close drain valve 7, and the entire shutdown and sealing process of the electric desalting tank is completed.

[0099] V. Final Inspection:

[0100] Confirm that all valves are closed (crude oil inlet valve 1, crude oil outlet valve 2, water injection valve 4, tank top safety valve crossover valve 5, tank top nitrogen valve 6, drain valve 7, tank bottom low-pressure steam valve 8, backwash water supply valve 9).

[0101] Record the final pressure, temperature, and total discharge within the tank to generate a treatment report.

[0102] In conjunction with subsequent tank cleaning operations (the cleaning workload for a single tank is only 2~4m³), after confirming that there is no residual oil or gas and a large amount of sludge in the tank, it is handed over to the maintenance phase.

[0103] Key points to note:

[0104] All operations must follow the "open before closing" principle to avoid pipeline pressure buildup and ensure accurate valve opening and closing status.

[0105] When steam boiling the tank, the steam supply rate must be controlled to prevent the pressure inside the tank from rising suddenly beyond the safe range. Safety valve 10 must be in normal standby mode.

[0106] During backwashing, it is necessary to ensure stable water pressure, uniform spraying, and improved cooling and mixing effects.

[0107] VOCs monitoring will be conducted throughout the entire process, and the discharge of oil, gas and wastewater on site is strictly prohibited to ensure compliance with environmental protection standards.

[0108] Finally, it should be noted that the above embodiments are merely examples for clearly illustrating the present invention and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An electric desalter tank shutdown containment method, the electric desalter tank shutdown containment method being implemented by an electric desalter tank shutdown containment system, characterized by, The electric desalting tank shutdown closed treatment system comprises an electric desalting tank body, a crude oil feeding pipeline, a crude oil outlet pipeline, a safety valve cross line and a close-packed pipeline. The crude oil feeding pipeline is provided with a crude oil feeding valve (1) and a raw material bypass valve (3), the raw material bypass valve (3) is connected in parallel to both ends of the crude oil feeding valve (1), and the crude oil feeding pipeline is further provided with a water injection process, and the water injection process is provided with a water injection valve (4). The tank top of the electric desalting tank body is provided with an outlet collector (11), the outlet collector (11) is communicated with one end of the crude oil outlet pipeline, the other end of the crude oil outlet pipeline is connected with a production refining system, and the crude oil outlet pipeline is provided with a crude oil outlet valve (2). The safety valve cross line is provided with a tank top safety valve cross line valve (5), and the tank top of the electric desalting tank body is further provided with a safety valve (10). One end of the close-packed pipeline is communicated with the tank bottom of the electric desalting tank body, the other end is connected with a sewage treatment field, and the close-packed pipeline is provided with a drainage valve (7). The electric desalting tank shutdown closed treatment method comprises the following steps: S1: independent cutting and main body oil recovery: opening the raw material bypass valve (3), closing the crude oil feeding valve (1), keeping the crude oil outlet valve (2) open; opening the water injection valve (4) to inject water into the tank to raise the oil-water interface, and the main body oil is collected through the tank top outlet collector (11) and then recovered to the production refining system through the crude oil outlet pipeline; S2: residual oil replacement recovery: closing the crude oil outlet valve (2), opening the tank top safety valve cross line valve (5), continuing to inject water through the water injection valve (4), replacing the residual oil between the tank top outlet collector (11) and the tank top, and the inlet and outlet pipe sections of the safety valve (10), and the residual oil is recovered to the flash tower / primary distillation tower through the safety valve cross line, and then the tank top safety valve cross line valve (5) and the water injection valve (4) are closed; S3: sewage discharge: opening the drainage valve (7), using the residual pressure in the tank to transport the sewage to the sewage treatment field through the close-packed pipeline; if the residual pressure is insufficient, the tank top nitrogen valve (6) is opened to pressurize by nitrogen, until the remaining sewage interface in the tank is 15%-20% of the tank capacity, and then the tank top nitrogen valve (6) and the drainage valve (7) are closed; S4: tank boiling and oil gas recovery: opening the tank bottom low-pressure steam valve (8) to introduce low-pressure steam to boil the tank, and opening the tank top safety valve cross line valve (5) to introduce the oil gas and water vapor generated by boiling the tank into the flare gas recovery system through the safety valve cross line; after boiling the tank, the tank bottom low-pressure steam valve (8) is closed, and after the residual oil gas is discharged, the tank top safety valve cross line valve (5) is closed; S5: backflushing and cooling and mixture discharge: opening the backflushing water valve (9), and introducing backflushing water into the tank through the backflushing distributor (12) for cooling and stirring; after the temperature in the tank is reduced to a preset value, the backflushing water valve (9) is closed, the drainage valve (7) is opened, and the oil-water mixture in the tank is transported to the sewage treatment field through the close-packed pipeline, and the drainage valve (7) is closed to complete the treatment.

2. A method of shutdown containment treatment of an electric desalter tank as claimed in claim 1, wherein, The electric desalting tank shutdown closed treatment system further comprises a low-pressure steam pipeline, one end of the low-pressure steam pipeline is communicated with the tank bottom of the electric desalting tank body, the other end is used for connecting a low-pressure steam source, and the low-pressure steam pipeline is provided with a tank bottom low-pressure steam valve (8).

3. A method of shutdown containment treatment of an electric desalter tank as recited in claim 1 wherein, The electric desalting tank shutdown sealed treatment system further comprises a backwashing water supply flow and a backwashing distributor (12); The backwashing distributor (12) is arranged inside the electric desalting tank body, one end of the backwashing water supply flow is communicated with the backwashing distributor (12), the other end is connected with a water source, and a backwashing water supply valve (9) is arranged on the backwashing water supply flow.

4. The method of claim 1, wherein the method further comprises, The electric desalting tank shutdown sealed treatment system further comprises a nitrogen pipeline, one end of the nitrogen pipeline is communicated with the tank top of the electric desalting tank body, the other end is connected with a nitrogen source, and a tank top nitrogen valve (6) is arranged on the nitrogen pipeline.

5. A method of shutdown containment treatment of an electric desalter tank as recited in claim 1 wherein, In the electric desalting tank shutdown sealed treatment system, the backwashing distributor (12) is in the form of a ring pipe, a plurality of spray holes are arranged on the pipe wall of the ring pipe, and the plurality of spray holes are uniformly distributed along the circumference of the ring pipe.

6. A method of shutdown containment treatment of an electrical desalter tank as recited in claim 1 wherein, In the electric desalting tank shutdown sealed treatment system, a one-way valve is arranged on the pipe section close to the production refining system in the crude oil outlet pipeline, and the conduction direction of the one-way valve is from the electric desalting tank body to the production refining system.

7. A method of shutdown containment treatment of an electric desalter tank as recited in claim 1 wherein, In the electric desalting tank shutdown sealed treatment system, a filter is arranged on the pipe section close to the sewage treatment field in the dense pipeline, and the filtering accuracy of the filter is 50-100 meshes.

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