Mechanical cleaning method for oil storage tank

Abstract

The invention discloses an oil storage tank mechanical cleaning method, relates to the technical field of oil tank cleaning, and can improve oil tank cleaning efficiency and cleaning safety. Under a safe environment, operators and equipment vehicles enter a site, the operators receive factory safety education, equipment and pipeline unloading and hoisting, equipment, pipeline and auxiliary facility connection, equipment debugging and pipeline pressure testing, protective gas injection, tank interior warm water cleaning, residual water transferring, acceptance and acceptance, and equipment and pipeline dismounting. By means of the working processes of construction site recovery, equipment material hoisting and evacuation, acceptance and handover and evacuation site, the oil tank cleaning efficiency can be greatly improved, and the cleaning safety is improved.

Description

Technical Field

[0001] The invention relates to the technical field of oil tank cleaning, and in particular to a mechanical cleaning method for an oil storage tank. Background Art

[0002] After the oil storage tank has been in operation or idle for a period of time, as impurities in the medium in the tank are deposited, the anti-corrosion layer falls off, and the heavy components condense and solidify, the effective capacity of the oil storage tank gradually decreases, the storage efficiency of the oil tank decreases, the tank wall and bottom plate gradually corrode or even leak oil, affecting the normal operation of the oil storage tank. Therefore, the oil storage tank needs to be cleaned regularly to remove the sludge in the tank.

[0003] There are two ways to clean oil tanks: manual cleaning and mechanical cleaning. However, the manual cleaning method has problems such as high operational risk, low cleaning efficiency, poor cleaning effect, high work intensity, and unorganized emission of oil, gas, and toxic and harmful gases. In recent years, mechanical cleaning of oil tanks has gradually become popular in my country, basically replacing the previous manual cleaning method. Compared with manual cleaning, it has the advantages of safety, environmental protection, and economic efficiency. With the increasing attention paid by society and enterprises to safety and environmental issues, mechanical cleaning will surely become a trend of future development. There are many mainstream cleaning methods in the world, but there are no effective measures in operating specifications, and there are still deficiencies in cleaning efficiency, which has a large room for improvement. At the same time, it does not have obvious advantages in cleaning safety. Summary of the invention

[0004] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art and to provide a mechanical cleaning method for an oil storage tank, which can improve the cleaning efficiency of the oil tank and improve the cleaning safety.

[0005] The present invention provides a method for mechanically cleaning an oil storage tank, comprising the following steps:

[0006] S1: Equipment and pipeline unloading and hoisting: hoist and place the circulating pumping skid and oil-water separation skid according to the approved layout diagram, and hoist and place the pipeline materials inside the firewall;

[0007] S2: Connection of equipment, pipelines and auxiliary facilities: Lay and connect recovery pipelines, transfer pipelines, residual oil transfer lines, oil supply pipelines, cleaning pipelines, steam pipelines, nitrogen pipelines, gas detection pipelines, oil-water pipelines, and water supply pipelines. All cleaning medium delivery pipelines are installed with electrostatic jumper lugs, and the pipelines are connected to the tank body grounding wire; install the tank top floating plate cleaning machine, install the tank top floating plate cleaning machine to the floating plate support position, and connect it to the cleaning pipeline on the tank top;

[0008] S3: Equipment debugging and pipeline pressure test: Check and debug the equipment according to the equipment pre-startup inspection record to ensure the normal operation of the equipment. At the same time, use nitrogen to conduct air tightness tests on each temporary pipeline to ensure that the pipeline is tightly connected and the cleaning project is carried out smoothly;

[0009] S4: Protective gas injection: nitrogen is injected into the tank through the nitrogen pipeline by the adsorption nitrogen generator skid to ensure that the oxygen content in the tank is below 8%;

[0010] S5: Warm water cleaning in the tank: clean water is passed into the oil-water separation skid, and the water in the oil-water separation skid is heated to 60-70℃ by steam, and then injected into the tank to be cleaned through the cleaning process. The tank is cleaned by the tank top floating plate cleaning machine, and the recovered medium is transferred to the oil-water separation skid through the circulation pumping skid, and the warm water is recycled. The separated crude oil is transferred to the adjacent oil storage tank through the residual oil transfer line;

[0011] S6: Residual water transfer: After cleaning, the oil content of the sediment in the tank is observed by measuring the ruler. When there is less sludge in the tank and the oil content is low, the residual water is transferred;

[0012] S7: Acceptance: After the mechanical cleaning of the oil tank is completed, check that there is no obvious residual oil in the tank;

[0013] S8: Equipment and pipeline dismantling and construction site restoration: Before dismantling and laying pipelines, sweep the lines to ensure that there is no residual sewage in the pipelines and confirm that there is no pressure in the pipelines. The dismantled pipelines and valves are packed in baskets according to specifications, the work site is cleaned, and the site and facilities are restored to their original state;

[0014] S9: Equipment and materials are hoisted and evacuated, signed and accepted on site, and the operating personnel evacuate the site.

[0015] A mechanical cleaning method for oil storage tanks according to an embodiment of the present invention has at least the following beneficial effects: in a safe environment, the operating personnel and equipment vehicles enter the site, the operating personnel receive safety education in the factory area → equipment and pipelines are unloaded and hoisted → equipment, pipelines and auxiliary facilities are connected → equipment debugging, pipeline pressure testing → protective gas injection → warm water cleaning in the tank → residual water transfer → acceptance → equipment and pipeline removal, restoration of the construction site → equipment and materials hoisting and evacuation, acceptance and handover, and evacuation of the site work process, which can greatly improve the efficiency of oil tank cleaning and improve cleaning safety.

[0016] According to a mechanical cleaning method for oil storage tanks described in the present invention, in step S2, the recovery pipeline is connected to the circulation pumping skid through the water cutout of the tank to be cleaned and the temporary manhole via an external filter, and the pipeline is connected to the equipment inlet with a hose to avoid stress concentration; the transfer pipeline is connected from the outlet of the circulation pumping skid to the water cutout of the oil storage tank; the residual oil transfer line is connected to the transfer pipeline by the diaphragm pump of the oil-water separation skid; the oil supply pipeline is connected to the circulation pumping skid from the water cutout of the oil storage tank; and the water supply pipeline is led from the water source to the oil-water separation skid.

[0017] According to a mechanical cleaning method for oil storage tanks described in the present invention, the cleaning pipeline is connected to the tank to be cleaned by a circulating pump skid, the cleaning pipeline on the ground is connected to the cleaning riser by the tank top floating cleaning machine, the cleaning riser is erected along the tank wall by a crane, fixedly connected to the riser rack, and then hoisted to connect the riser inside the tank, and the ground cleaning pipeline and the cleaning pipeline on the floating plate are connected.

[0018] According to a mechanical cleaning method for oil storage tanks described in the present invention, the steam pipeline is skidded from the boiler to the heat exchanger and the oil-water separation skid; the nitrogen pipeline is inserted into the tank to be cleaned through the central gauge port of the floating tank, and the insertion depth is more than 200mm from the oil surface. Before nitrogen is injected, the primary and secondary sealing conditions of the floating plate, the sealing condition of the pillars, and the sealing condition of the manhole are checked.

[0019] According to a mechanical cleaning method for oil storage tanks described in the present invention, a gas detection pipeline is led from the outlet of a gas detection device to a manhole or a gauge port on the tank top of the tank to be cleaned, the gas detection pipeline is evenly distributed on the floating plate of the tank to be cleaned, and the gas in the oil tank to be cleaned is extracted by a suction pump of a gas detection instrument. The insertion position of the gas detection pipeline includes the tank top breathing valve, the central sampling port, and the support position and the floating plate position next to it. The gas detection pipeline is composed of a plurality of ethylene resin hoses with a diameter of 10 mm, and the portion inserted into the tank is more than 300 mm away from the oil surface.

[0020] According to a mechanical cleaning method for oil storage tanks described in the present invention, in step S2, a tank top floating plate cleaning machine is installed at the position of the floating plate support, and an explosion-proof tool is used to pull out the floating plate support when the floating roof floats up, and the total amount of the pulled-out support does not exceed 20% of the total amount of the floating roof support, and adjacent supports shall not be pulled out in the circumferential direction and the radial direction. Before inserting the tank top floating plate cleaning machine, a measuring rod is used to confirm the height of the support sleeve, and the tank top floating plate cleaning machine is fastened to the fixed sleeve to prevent the tank top floating plate cleaning machine from swinging during operation.

[0021] According to the mechanical cleaning method for oil storage tanks described in the present invention, step S3 is to inspect and debug the equipment, check the mechanical seal of the pump, the alignment with the motor, check the metering and measuring equipment, check the protective equipment, check the sealing condition of the floating roof, and seal the leaking parts.

[0022] According to a mechanical cleaning method for oil storage tanks described in the present invention, in step S3, nitrogen is used to perform an air tightness test on four groups of pipelines, namely, the recovery pipeline, the transfer pipeline, the oil supply pipeline, and the cleaning pipeline. The pressure is 0.7MPa, pressurized to 1.5 times the working pressure value, and the pressure is stabilized for 30 minutes. The operator checks the flange connection surface, the valve stuffing box position, and the pump mechanical seal, and sprays soapy water for leak detection. After the pressure test is completed, the pressure is released into the oil-water separation skid, and the pressure test record sheet must be filled in at the same time.

[0023] According to a mechanical cleaning method for oil storage tanks described in the present invention, in step S5, a tank top floating plate cleaning machine is used to clean the tank to be cleaned. When the flowable crude oil in the cleaning tank is sucked out and the sediment is completely exposed in the space, heated clean water is added, the cleaning equipment is started, and hot water is provided to the cleaning equipment from the oil-water separation skid. The cleaning medium is pressurized by the cleaning pump, and the temperature is raised by the heat exchanger, and then the cleaning medium is transported to the tank top floating plate cleaning machine, and the sediment in the tank is subjected to pressure shock to crush the dissolved sediment, which is then recovered by the recovery equipment and transferred to the tank truck; the tank top floating plate cleaning machine adopts the bottom plate mode during cleaning, and the outer tank top floating plate cleaning machine is first started, and cleaning starts from the suction port to crush and dissolve the outer sediment, and the outer circle is cleaned in this way. After the outer tank top floating plate cleaning machine completes the cleaning action, the middle tank top floating plate cleaning machine is started again, and the cleaning is alternately circulated; after the tank bottom sediment is basically dissolved, the starting sequence of the tank top floating plate cleaning machine starts from the middle tank top floating plate cleaning machine to operate toward the periphery.

[0024] According to the mechanical cleaning method for oil storage tanks described in the present invention, in step S5, the residual oil in the tank is transferred to the oil storage tank. When the liquid level in the tank is 20 cm lower than the tank top plate, nitrogen injection is started during the transfer, and finally the transfer is stopped when it is ensured that the liquid level in the tank is lower than the manhole of the tank wall, that is, the liquid level in the tank is 400 mm.

[0025] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention is further described below in conjunction with the accompanying drawings and embodiments;

[0027] Figure 1 The process flow chart of the preferred embodiment of the present invention is as follows;

[0028] Figure 2 It is a plan view of the equipment arrangement of a preferred embodiment of the present invention;

[0029] Figure 3 This is a flow chart of warm water cleaning in a cleaning tank according to a preferred embodiment of the present invention;

[0030] Figure 4 The figure is a flow chart of residual oil recovery in a preferred embodiment of the present invention.

[0031] Figure numerals: circulating pumping skid 1, oil-water separation skid 2, recovery pipeline 3, transfer pipeline 4, residual oil transfer line 5, oil supply pipeline 6, cleaning pipeline 7, steam pipeline 8, nitrogen pipeline 9, gas detection pipeline 10, oil-water pipeline 11, water supply pipeline 12, tank top floating plate cleaning machine 13, adsorption nitrogen generating skid 14, cleaned tank 15, oil storage tank 16. DETAILED DESCRIPTION

[0032] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0033] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0034] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood as not including the number itself, and "above", "below", "within" etc. are understood as including the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0035] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0036] Reference Figures 1 to 4 , a method for mechanical cleaning of an oil storage tank comprises the following steps:

[0037] S1: Equipment and pipeline unloading and hoisting: hoist and place the circulating pumping skid 1 and oil-water separation skid 2 according to the approved layout diagram, and hoist and place the pipeline materials inside the firewall;

[0038] S2: Connection of equipment, pipelines and auxiliary facilities: Lay and connect recovery pipeline 3, transfer pipeline 4, residual oil transfer line 5, oil supply pipeline 6, cleaning pipeline 7, steam pipeline 8, nitrogen pipeline 9, gas detection pipeline 10, oil-water pipeline 11, water supply pipeline 12. All cleaning medium delivery pipelines are installed with electrostatic jumper lugs, and the pipelines are connected to the tank body grounding wire; install the tank top floating plate cleaning machine 13, install the tank top floating plate cleaning machine 13 to the floating plate support position, and connect it to the cleaning pipeline 7 on the tank top;

[0039] S3: Equipment debugging and pipeline pressure test: Check and debug the equipment according to the equipment pre-startup inspection record to ensure the normal operation of the equipment. At the same time, use nitrogen to conduct air tightness tests on each temporary pipeline to ensure that the pipeline is tightly connected and the cleaning project is carried out smoothly;

[0040] S4: Protective gas injection: nitrogen is injected into the tank through the nitrogen pipeline 9 by the adsorption nitrogen generating skid 14 to ensure that the oxygen content in the tank is below 8%;

[0041] S5: Tank warm water cleaning: clean water is passed into the oil-water separation skid 2, and the water in the oil-water separation skid 2 is heated to 60-70°C by steam, and then injected into the tank to be cleaned 15 through the cleaning process, and the tank is cleaned by the tank top floating plate cleaning machine 13, and the recovered medium is transferred to the oil-water separation skid 2 through the circulating pumping skid 1, and the warm water is circulated and used, and the separated crude oil is transferred to the adjacent oil storage tank 16 through the residual oil transfer line 5;

[0042] S6: Residual water transfer: After cleaning, the oil content of the sediment in the tank is observed by measuring the ruler. When there is less sludge in the tank and the oil content is low, the residual water is transferred;

[0043] S7: Acceptance: After the mechanical cleaning of the oil tank is completed, check that there is no obvious residual oil in the tank;

[0044] S8: Equipment and pipeline dismantling and construction site restoration: Before dismantling and laying pipelines, sweep the lines to ensure that there is no residual sewage in the pipelines and confirm that there is no pressure in the pipelines. The dismantled pipelines and valves are packed in baskets according to specifications, the work site is cleaned, and the site and facilities are restored to their original state;

[0045] S9: Equipment and materials are hoisted and evacuated, signed and accepted on site, and the operating personnel evacuate the site.

[0046] It is understandable that, under the premise of ensuring a safe environment, the work process of workers and equipment vehicles entering the site, workers receiving safety education in the factory → equipment and pipelines unloading and hoisting → equipment, pipelines and auxiliary facilities connection → equipment commissioning, pipeline pressure testing → protective gas injection → warm water cleaning in the tank → residual water transfer → acceptance → equipment and pipeline dismantling, restoration of the construction site → equipment and materials hoisting and evacuation, acceptance and handover, and evacuation of the site can greatly improve the efficiency of oil tank cleaning and improve cleaning safety.

[0047] Furthermore, before step S1, the engineering metering equipment performs calibration of liquid flow and pressure before arriving at the construction site to ensure accurate metering of the equipment during the construction process.

[0048] In step S1, the construction manager formulates the hoisting procedures and determines the hoisting path according to the site conditions, clarifies the hoisting command signals, hoisting command personnel, equipment placement, and hoisting walking routes, ensures the safety of the operators, on-site equipment, and facilities, and hoists and places the circulating pumping skid 1 and the oil-water separation skid 2 according to the approved placement diagram. The pipeline materials are hoisted and placed within the firewall, which can also be slightly adjusted according to the site conditions.

[0049] In step S2, the recovery pipeline 3, transfer pipeline 4, residual oil transfer line 5, oil supply pipeline 6, cleaning pipeline 7, steam pipeline 8, nitrogen pipeline 9, gas detection pipeline 10, oil-water pipeline 11, and water supply pipeline 12 are laid and connected. All cleaning medium delivery pipelines are installed with static jumper lugs, and the pipelines are connected to the tank grounding wire to ensure that the static electricity of the pipelines can be released in time. Among them:

[0050] The recovery pipeline 3 is connected to the circulation pumping skid 1 through the cut-out 17 of the cleaned tank 15 and the temporary manhole 18 via the external filter 19. The pipeline is connected to the equipment inlet with a hose to avoid stress concentration. The integrity of the valve and the integrity of the valve flange surface should be checked before connection and installation. Pay attention to the directionality when connecting the filter 19.

[0051] The transfer pipeline 4 is connected from the outlet of the circulating pumping skid 1 to the water cut-off of the oil storage tank 16 .

[0052] The residual oil transfer line 5 is connected to the transfer pipeline 4 by the diaphragm pump 20 of the oil-water separation skid 2 .

[0053] The oil supply pipeline 6 is connected to the circulation pumping skid 1 through the water cut-out of the oil storage tank 16 .

[0054] The cleaning pipeline 7 is connected to the cleaned tank 15 by the circulating pumping skid 1. In addition, the ground cleaning pipeline is connected to the cleaning riser by the tank top floating cleaning machine 13. The cleaning riser is erected along the tank wall by a crane and fixedly connected to the riser rack. The riser inside the tank is then hoisted and connected to connect the ground cleaning pipeline and the cleaning pipeline on the floating platform.

[0055] The steam pipeline 8 is a pipeline from the boiler skid to the heat exchanger and the oil-water separation skid 2, which is used to increase the temperature of the cleaning medium. The steam pipeline 8 is laid with a DN50 steel pipe, and the personnel entry and exit areas are insulated and protected with warning tapes.

[0056] The nitrogen pipeline 9 is inserted into the tank 15 to be cleaned through the central gauge port of the floating tank. The insertion depth is more than 200mm from the oil surface. Before nitrogen injection, check the primary and secondary sealing of the floating plate, the sealing of the pillars, and the sealing of the manhole; seal the insertion port of the tank top floating plate cleaning machine 13, the gas detection port, the breathing valve and other leaking parts, which can be sealed with stretch film or sealing bags.

[0057] The gas detection pipeline 10 is led from the outlet of the gas detection device 21 to the manhole or the inspection port on the tank top of the cleaned tank 15. The gas detection pipeline 10 is evenly distributed on the floating plate of the cleaned tank. The gas in the cleaned oil tank is extracted by the suction pump of the gas detection instrument. The insertion position of the gas detection pipeline 10 includes the tank top breathing valve, the central sampling port and the support position and the floating plate position next to it. The gas detection pipeline 10 is composed of multiple vinyl resin hoses with a diameter of 10mm, and the part inserted into the tank is more than 300mm away from the oil surface; the water supply pipeline 12 is led from the water source to the oil-water separation skid 2.

[0058] Install the tank top floating plate cleaning machine 13, install the tank top floating plate cleaning machine 13 to the floating plate support position, use explosion-proof tools to pull out the floating plate support when the floating roof floats, the total amount of the pulled out support should not exceed 20% of the total amount of the floating roof support, and the adjacent support should not be pulled out in the circumferential direction and the radial direction. After the support is pulled out, clean the support oil in time, and seal the support sleeve in time; before inserting the tank top floating plate cleaning machine 13, use a ruler to confirm the height of the support sleeve, and at the same time consider whether there are obstacles such as heating coils at the insertion position of the tank top floating plate cleaning machine 13, and tighten the tank top floating plate cleaning machine 13 to the fixed sleeve to prevent the tank top floating plate cleaning machine 13 from swinging during operation. The connection between the cleaning branch pipe and the tank top floating plate cleaning machine 13 should be firmly connected, and the pipelines should be neatly arranged.

[0059] In step S3, the equipment is inspected and debugged according to the equipment pre-startup inspection record sheet, the pump's mechanical seal and the degree of alignment with the motor are checked, the metering and measuring equipment are checked, the protective equipment is checked, the sealing of the floating roof is checked, and the leaking parts are sealed to ensure the normal operation of the equipment. At the same time, nitrogen is used to conduct air tightness tests on each temporary pipeline, including air tightness tests on four groups of pipelines: recovery pipeline 3, transfer pipeline 4, oil supply pipeline 6, and cleaning pipeline 7. The pressure is 0.7MPa, pressurized to 1.5 times the working pressure value, and the pressure is stabilized for 30 minutes. The operator checks the parts including the flange connection surface, the valve stuffing box position, and the pump mechanical seal, sprays soapy water for leak detection, and after the pressure test is completed, the pressure is released into the oil-water separation skid 2. At the same time, the pressure test record sheet must be filled in to ensure that the pipeline is tightly connected and the cleaning project is carried out smoothly.

[0060] In step S4, nitrogen is injected into the tank through the nitrogen pipeline 9 by the adsorption nitrogen generating skid 14. During the cleaning process, nitrogen is injected into the cleaning tank to reduce the oxygen concentration in the tank to below 8%, thereby ensuring the safety of the cleaning environment in the tank.

[0061] In step S5, clean water is passed into the oil-water separation skid 2, and the water in the oil-water separation skid 2 is heated to 60-70°C by steam, and then injected into the tank to be cleaned 15 through the cleaning process, and the tank is cleaned by the tank top floating plate cleaning machine 13. The recovered medium is transferred to the oil-water separation skid 2 through the circulating pumping skid 1, and the warm water is recycled. The separated crude oil is transferred to the adjacent oil storage tank 16 through the residual oil transfer line 5; the oxygen content is controlled to be below 8% during the warm water process.

[0062] The tank 15 to be cleaned is cleaned by using the tank top floating plate cleaning machine 13. When the flowable crude oil in the tank is basically sucked out and the sediment is completely exposed in the space, the heated clean water is added, the cleaning equipment is started, and the hot water is provided to the cleaning equipment from the oil-water separation skid 2. The cleaning medium is pressurized by the cleaning pump, and the temperature of the cleaning medium is increased through the heat exchanger and transported to the tank top floating plate cleaning machine 13. The sediment in the tank is subjected to pressure shock to break up the dissolved sediment, which is then recovered by the recovery equipment and transferred to the tank truck.

[0063] The tank top floating plate cleaning machine 13 adopts the bottom plate mode during cleaning. The outer tank top floating plate cleaning machine 13 is started first, and cleaning starts from the suction port to break and dissolve the outer sediments. The outer circle is cleaned by analogy. After the outer tank top floating plate cleaning machine 13 completes the cleaning action, the middle tank top floating plate cleaning machine 13 is started again, and the cleaning is carried out in an alternating cycle. After the sediments on the bottom of the tank are basically dissolved, the starting sequence of the tank top floating plate cleaning machine 13 starts from the middle tank top floating plate cleaning machine 13 and operates toward the periphery.

[0064] The residual oil in the tank is transferred to the oil storage tank 16. When the liquid level in the tank is 20 cm lower than the tank top plate, nitrogen injection is started during the transfer to ensure that the liquid level in the tank is lower than the manhole on the tank wall. That is, the transfer is stopped when the liquid level in the tank is 400 mm.

[0065] In step S6, after the entire cleaning is completed, the oil content of the sediment in the tank is observed by measuring the gauge. When the sludge in the tank is less and the oil content is low, the residual water is transferred, and the next process starts after the transfer is completed.

[0066] In step S7, after the mechanical cleaning of the oil tank is completed, check that there is no obvious residual oil in the tank.

[0067] In step S8, the pipeline is swept before dismantling and laying to ensure that there is no residual sewage in the pipeline, confirm that there is no pressure in the pipeline, and promptly collect the dismantled bolts and gaskets to keep the site clean. The dismantled pipelines and valves are packed in baskets according to specifications, and the faulty equipment is marked for subsequent maintenance. The instruments and meters are well protected, and the unused consumables are promptly organized for subsequent use. The work site is cleaned and the site and facilities are restored to their original state.

[0068] In step S9, the equipment and materials are hoisted and evacuated, the on-site signature acceptance and handover are completed, and the operating personnel evacuate the site.

[0069] As a further improvement of the above scheme, in step S2, the recovery pipeline 3 is connected to the circulation pumping skid 1 by the cut-out 17 of the cleaned tank 15 and the temporary manhole 18 via the external filter 19, and the pipeline is connected to the equipment inlet with a hose to avoid stress concentration; the transfer pipeline 4 is connected from the outlet of the circulation pumping skid 1 to the cut-out of the oil storage tank 16; the residual oil transfer line 5 is connected to the transfer pipeline 4 by the diaphragm pump 20 of the oil-water separation skid 2; the oil supply pipeline 6 is connected to the circulation pumping skid 1 by the cut-out of the oil storage tank 16; the water supply pipeline 12 is led from the water source to the oil-water separation skid 2.

[0070] As a further improvement of the above scheme, the cleaning pipeline 7 is connected to the cleaned tank 15 by the circulating pumping skid 1, and the ground cleaning pipeline 7 is connected to the cleaning riser by the tank top floating platform cleaning machine 13. The cleaning riser is erected along the tank wall by a crane and fixedly connected to the riser rack. Then, the riser inside the connection tank is hoisted and connected. The ground cleaning pipeline 7 and the cleaning pipeline 7 on the floating platform are connected.

[0071] As a further improvement of the above scheme, the steam pipeline 8 is a pipeline from the boiler skid to the heat exchanger and the oil-water separation skid 2; it is used to increase the temperature of the cleaning medium. The nitrogen pipeline 9 is inserted into the tank 15 to be cleaned through the central gauge port of the floating tank, and the insertion depth is more than 200mm from the oil surface. Before nitrogen injection, check the primary and secondary sealing of the floating plate, the sealing of the pillars, and the sealing of the manhole.

[0072] As a further improvement of the above scheme, the gas detection pipeline 10 is led from the outlet of the gas detection device 21 to the manhole or the inspection port on the tank top of the cleaned tank 15. The gas detection pipeline 10 is evenly distributed on the floating plate of the cleaned tank. The gas in the cleaned oil tank is extracted by the suction pump of the gas detection instrument. The insertion position of the gas detection pipeline 10 includes the tank top breathing valve, the central sampling port and the support position and the floating plate position next to it. The gas detection pipeline 10 is composed of multiple vinyl resin hoses with a diameter of 10 mm, and the part inserted into the tank is more than 300 mm away from the oil surface.

[0073] As a further improvement of the above scheme, in step S2, the tank top floating plate cleaning machine 13 is installed at the position of the floating plate support. When the floating roof floats up, the floating plate support is pulled out by explosion-proof tools. The total amount of the pulled out support does not exceed 20% of the total amount of the floating roof support. Adjacent supports shall not be pulled out in the circumferential direction or the radial direction. Before inserting the tank top floating plate cleaning machine 13, the height of the support sleeve is confirmed by a measuring rod, and the tank top floating plate cleaning machine 13 is fastened to the fixed sleeve to prevent the tank top floating plate cleaning machine 13 from swinging during operation.

[0074] As a further improvement of the above scheme, step S3 inspects and debugs the equipment, checks the mechanical seal of the pump, the alignment with the motor, the metering and measuring equipment, the protective equipment, the sealing condition of the floating roof, and seals the leaking parts.

[0075] As a further improvement of the above scheme, in step S3, nitrogen is used to conduct air tightness tests on four groups of pipelines, namely, the recovery pipeline 3, the transfer pipeline 4, the oil supply pipeline 6, and the cleaning pipeline 7. The pressure is 0.7 MPa, and the pressure is increased to 1.5 times the working pressure value. The pressure is maintained for 30 minutes. The operator checks the flange connection surface, the valve stuffing box position, and the pump mechanical seal, and sprays soapy water for leak detection. After the pressure test is completed, the pressure is released into the oil-water separation skid 2, and the pressure test record sheet must be filled in.

[0076] As a further improvement of the above scheme, in step S5, the tank 15 to be cleaned is cleaned by using the tank top floating plate cleaning machine 13. When the flowable crude oil in the cleaning tank 15 is sucked out and the sediment is completely exposed in the space, the heated clean water is added, the cleaning equipment is started, and the hot water is provided to the cleaning equipment from the oil-water separation skid 2. The cleaning medium is pressurized by the cleaning pump, and the cleaning medium is heated by the heat exchanger and transported to the tank top floating plate cleaning machine 13. The sediment in the tank is subjected to pressure shock to crush the dissolved sediment, which is then recovered by the recovery equipment and transferred to the tank truck; the tank top floating plate cleaning machine 13 adopts the bottom plate mode during cleaning, and the outer tank top floating plate cleaning machine 13 is started first, and the cleaning starts from the suction port to crush and dissolve the outer sediment, and the outer circle is cleaned by analogy. After the outer tank top floating plate cleaning machine 13 completes the cleaning action, the middle tank top floating plate cleaning machine 13 is started again, and the cleaning is alternately circulated; after the sediment at the bottom of the tank is basically dissolved, the start sequence of the tank top floating plate cleaning machine 13 starts from the middle tank top floating plate cleaning machine 13 to the periphery.

[0077] As a further improvement of the above scheme, step S5 transfers the residual oil in the tank to the oil storage tank 16. When the liquid level in the tank is 20 cm lower than the tank top plate, nitrogen injection is started during the transfer, and finally the liquid level in the tank is ensured to be lower than the manhole of the tank wall, that is, the transfer is stopped when the liquid level in the tank is 400 mm.

[0078] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in the technical field without departing from the purpose of the present invention.

Claims

1. A method for mechanical cleaning of an oil storage tank, characterized in that: The following steps are involved: S1: Equipment and pipeline unloading and hoisting: hoist and place the circulating pumping skid and oil-water separation skid according to the approved layout diagram, and hoist and place the pipeline materials inside the firewall; S2: Connection of equipment, pipelines and auxiliary facilities: Lay and connect recovery pipelines, transfer pipelines, residual oil transfer lines, oil supply pipelines, cleaning pipelines, steam pipelines, nitrogen pipelines, gas detection pipelines, oil-water pipelines, and water supply pipelines. All cleaning medium delivery pipelines are installed with electrostatic jumper lugs, and the pipelines are connected to the tank body grounding wire; install the tank top floating plate cleaning machine, install the tank top floating plate cleaning machine to the floating plate support position, and connect it to the cleaning pipeline on the tank top; S3: Equipment debugging and pipeline pressure test: Check and debug the equipment according to the equipment pre-startup inspection record to ensure the normal operation of the equipment. At the same time, use nitrogen to conduct air tightness tests on each temporary pipeline to ensure that the pipeline is tightly connected and the cleaning project is carried out smoothly; S4: Protective gas injection: nitrogen is injected into the tank through the nitrogen pipeline by the adsorption nitrogen generator skid to ensure that the oxygen content in the tank is below 8%; S5: Warm water cleaning in the tank: clean water is passed into the oil-water separation skid, and the water in the oil-water separation skid is heated to 60-70℃ by steam, and then injected into the tank to be cleaned through the cleaning process. The tank is cleaned by the tank top floating plate cleaning machine, and the recovered medium is transferred to the oil-water separation skid through the circulation pumping skid, and the warm water is recycled. The separated crude oil is transferred to the adjacent oil storage tank through the residual oil transfer line; S6: Residual water transfer: After cleaning, the oil content of the sediment in the tank is observed by measuring the ruler. When there is less sludge in the tank and the oil content is low, the residual water is transferred; S7: Acceptance: After the mechanical cleaning of the oil tank is completed, check that there is no obvious residual oil in the tank; S8: Equipment and pipeline dismantling and construction site restoration: Before dismantling and laying pipelines, sweep the lines to ensure that there is no residual sewage in the pipelines and confirm that there is no pressure in the pipelines. The dismantled pipelines and valves are packed in baskets according to specifications, the work site is cleaned, and the site and facilities are restored to their original state; S9: Equipment and materials are hoisted and evacuated, signed and accepted on site, and the operating personnel evacuate the site.

2. The method for mechanical cleaning of an oil storage tank according to claim 1, characterized in that: In step S2, the recovery pipeline is connected to the circulation pumping skid from the cut-out of the tank to be cleaned and the temporary manhole via an external filter, and the pipeline is connected to the equipment inlet with a hose; the transfer pipeline is connected from the outlet of the circulation pumping skid to the cut-out of the oil storage tank; the residual oil transfer line is connected to the transfer pipeline by the diaphragm pump of the oil-water separation skid; the oil supply pipeline is connected to the circulation pumping skid from the cut-out of the oil storage tank; and the water supply pipeline is led from the water source to the oil-water separation skid.

3. The method for mechanical cleaning of an oil storage tank according to claim 1, characterized in that: The cleaning pipeline is connected to the tank to be cleaned by a circulating pump skid, and the ground cleaning pipeline is connected to the cleaning riser by the tank top floating cleaning machine. The cleaning riser is erected along the tank wall by a crane and fixedly connected to the riser rack. It is then hoisted and connected to the riser inside the tank. The ground cleaning pipeline and the cleaning pipeline on the floating platform are connected.

4. The method for mechanical cleaning of an oil storage tank according to claim 1, characterized in that: The steam pipeline is skidded from the boiler to the heat exchanger and the oil-water separation skid; the nitrogen pipeline is inserted into the tank to be cleaned through the central gauge port of the floating tank, and the insertion depth is more than 200mm from the oil surface. Before nitrogen injection, check the primary and secondary sealing of the floating plate, the sealing of the pillars, and the sealing of the manhole.

5. The method for mechanical cleaning of an oil storage tank according to claim 1, characterized in that: The gas detection pipeline is led from the outlet of the gas detection device to the manhole or inspection port on the tank top of the cleaned tank. The gas detection pipeline is evenly distributed on the floating plate of the cleaned tank. The gas in the cleaned oil tank is extracted by the suction pump of the gas detection instrument. The insertion parts of the gas detection pipeline include the tank top breathing valve, the central sampling port, and the support position and floating plate position next to it. The gas detection pipeline is composed of multiple vinyl resin hoses with a diameter of 10mm, and the part inserted into the tank is more than 300mm away from the oil surface.

6. The method for mechanical cleaning of an oil storage tank according to claim 1, characterized in that: In step S2, the tank top floating plate cleaning machine is installed at the floating plate support position. When the floating roof floats up, the floating plate support is pulled out with explosion-proof tools. The total amount of the pulled out support does not exceed 20% of the total amount of the floating roof support. Adjacent supports shall not be pulled out in the circumferential direction or the radial direction. Before inserting the tank top floating plate cleaning machine, the height of the support sleeve is confirmed with a measuring rod, and the tank top floating plate cleaning machine is fastened to the fixed sleeve to prevent the tank top floating plate cleaning machine from swinging during operation.

7. The method for mechanical cleaning of an oil storage tank according to claim 1, characterized in that: Step S3 is to inspect and debug the equipment, check the mechanical seal of the pump, the alignment with the motor, check the metering and measuring equipment, check the protective equipment, check the sealing of the floating roof, and seal the leaking parts.

8. The method for mechanical cleaning of an oil storage tank according to claim 1, characterized in that: Step S3: Use nitrogen to conduct air tightness test on four groups of pipelines, namely, recovery pipeline, transfer pipeline, oil supply pipeline and cleaning pipeline. The pressure is 0.7MPa and pressurized to 1.5 times of the working pressure value. The pressure is maintained for 30 minutes. The operator checks the flange connection surface, valve stuffing box position and pump mechanical seal, sprays soapy water for leak detection. After the pressure test is completed, the pressure is released into the oil-water separation skid, and the pressure test record sheet is filled in.

9. The method for mechanical cleaning of an oil storage tank according to claim 1, characterized in that: Step S5 uses the tank top floating plate cleaning machine to clean the tank to be cleaned. When the flowable crude oil in the cleaning tank is sucked out and the sediment is completely exposed in the space, the heated clean water is added, the cleaning equipment is started, and the hot water is provided to the cleaning equipment from the oil-water separation skid. The cleaning medium is pressurized by the cleaning pump, and the cleaning medium is heated by the heat exchanger and transported to the tank top floating plate cleaning machine to perform pressure shock on the sediment in the tank to crush the dissolved sediment, which is then recovered by the recovery equipment and transferred to the tank truck; the tank top floating plate cleaning machine adopts the bottom plate mode when cleaning, first starts the outer tank top floating plate cleaning machine, starts cleaning from the suction port, crushes and dissolves the outer sediment, and completes the cleaning of the outer circle in turn. After the outer tank top floating plate cleaning machine completes the cleaning action, the middle tank top floating plate cleaning machine is started again, and the cleaning is alternately circulated; after the sediment at the bottom of the tank is basically dissolved, the startup sequence of the tank top floating plate cleaning machine starts from the middle tank top floating plate cleaning machine to operate toward the periphery.

10. The method for mechanical cleaning of an oil storage tank according to claim 1, characterized in that: Step S5 transfers the residual oil in the tank to the oil storage tank. When the liquid level in the tank is 20 cm lower than the tank top plate, nitrogen injection is started during the transfer to ensure that the liquid level in the tank is lower than the manhole on the tank wall. That is, the transfer is stopped when the liquid level in the tank is 400 mm.

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