Sweeping system and sweeping method for tanker and chemical tanker

Abstract

The invention relates to a sweeping system and a sweeping method for an oil tanker and a chemical tanker, the sweeping system is arranged in a main deck area of a ship, each cargo hold on a main deck is provided with a cargo oil pump, and the sweeping system comprises a sweeping pipe system, a pneumatic injection pump, a gas-liquid separation cabinet and a spark-free pneumatic diaphragm pump; the sweeping pipe system comprises a plurality of sweeping pipes, a cargo oil pump of each cargo hold is matched with one sweeping pipe, one end of each sweeping pipe extends into an oil suction well at the bottom of the corresponding cargo oil pump, and the other end of each sweeping pipe is connected to a pneumatic injection pump; an auxiliary suction hole is formed in the sweeping pipe; a suction pipe of the pneumatic injection pump is connected with a sweeping pipe of each cargo hold, and the output end of the pneumatic injection pump is connected to the gas-liquid separation cabinet; a suction inlet of the non-spark pneumatic diaphragm pump is connected with the gas-liquid separation cabinet, and an exhaust port of the non-spark pneumatic diaphragm pump is connected to the collecting pipe area or the residual liquid cabin. The device overcomes the liquid level difference of a high cabin, reduces residual liquid residues, avoids goods pollution, is high in safety and adaptability, and improves the cabin sweeping efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ship cargo oil system, and particularly relates to a tank cleaning system and tank cleaning method for a chemical tanker, which is suitable for low-residue and pollution-free tank cleaning operation after high-value chemical transportation. BACKGROUND

[0002] During the cargo transportation of a chemical tanker, a certain amount of cargo is usually left in the cargo tank after the cargo is unloaded. The traditional tank cleaning method has many limitations, and the prior art has the following defects: (1) Difficulty in pumping with high liquid level difference For a high tank, such as a tank higher than 10 meters, the traditional pump cannot effectively pump the residual liquid at the bottom of the tank due to the high liquid level difference, and the residual liquid in a single tank exceeds the upper limit of 75L of the industry standard, resulting in a large amount of residual cargo. Not only does it cause resource waste and lead to waste of high-value chemicals, but it also may cause cross-contamination during subsequent transportation of different cargos. For extremely high-value chemicals, even a small amount of residue can cause huge economic losses, and cross-contamination can seriously affect their quality and value.

[0003] (2) Risk of cargo contamination Some tank cleaning equipment may contaminate the cargo during operation, such as mechanical pump wear debris and the possibility of lubricating oil mixing with the cargo to contaminate the cargo. The cleaning process may cause secondary pollution, which cannot meet the requirements of high-purity chemicals such as pharmaceutical intermediates and high-end electronic chemicals.

[0004] (3) Safety hazards When dealing with flammable and explosive cargos, the electrical components of the existing tank cleaning equipment may produce sparks, which may ignite flammable cargos. Compressed air blowing cannot solve the problem of oil and gas accumulation.

[0005] Although some improved tank cleaning technologies are available on the market, they still cannot fully solve the above problems. For example, some technologies increase the power of the pump to improve the pumping capacity, but they still cannot adapt to high tank liquid level difference and complex cargo characteristics. Some use compressed air blowing, which is not effective in dealing with high-viscosity cargos, and cannot effectively control the residual liquid residue at a low level, especially for high-value chemical tank cleaning operations.

[0006] Therefore, there is an urgent need for a tank cleaning system and method for a chemical tanker to solve the above problems. SUMMARY

[0007] The oil tanker and chemical tanker's tank cleaning system and tank cleaning method provided by the present application can overcome the high tank liquid level difference, reduce the residual liquid residue, control the single tank to be below 20L, avoid the cargo pollution, have high safety and strong adaptability, are especially suitable for high-value chemicals, can meet the relevant specification requirements, and improve the tank cleaning efficiency.

[0008] The present application is achieved as follows: The oil tanker and chemical tanker's tank cleaning system is arranged on the main deck area of a ship, each cargo tank on the main deck is provided with a cargo oil pump, and the tank cleaning system comprises a tank cleaning pipe system, a pneumatic jet pump, a gas-liquid separation tank and a sparkless pneumatic diaphragm pump. The suction pipe of the pneumatic jet pump is connected to the tank cleaning pipe of each cargo tank, the pneumatic jet pump is driven by full pneumatic, the output end of the pneumatic jet pump is connected to the gas-liquid separation tank, the gas-liquid separation tank is arranged on the main deck, and the gas-liquid separation tank is provided with a gas-liquid separation layer, a liquid level meter, a thermometer, a first liquid level switch and a second liquid level switch. The suction inlet of the sparkless pneumatic diaphragm pump is connected to the gas-liquid separation tank, and the discharge outlet of the sparkless pneumatic diaphragm pump is connected to the header zone or the residual liquid tank.

[0009] Further, the auxiliary suction hole is 0.8m to 1.5m away from the bottom end of the tank cleaning pipe.

[0010] Further, the tank cleaning pipe is made of 316L stainless steel pipe or inner lining polytetrafluoroethylene.

[0011] Further, the inner wall of the tank cleaning pipe is provided with mirror polishing treatment, the roughness of the inner wall is not greater than 0.8μm, and the adhesion and residue of high-value chemicals on the pipe wall are reduced.

[0012] Further, the auxiliary suction hole has a hole diameter of 1 / 20 to 1 / 30 of the inner diameter of the tank cleaning pipe, and the hole diameter accuracy of the auxiliary suction hole is controlled to be ±0.02mm, so that the gas mixing amount is stable, and the suction efficiency fluctuation and cargo residue increase caused by the hole diameter error are avoided.

[0013] Further, the cargo-contacting part of the pneumatic jet pump is made of corrosion-resistant and low-absorption materials such as Hastelloy or polytetrafluoroethylene, so as to reduce the residue and adsorption of the cargo on the surface of the pump body; the inner surface of the gas-liquid separation tank is subjected to electrolytic polishing treatment, so as to reduce the liquid residue dead angle and the material is selected to be the same as the corrosion-resistant and low-absorption material of the scavenging pipe.

[0014] Further, the gas-liquid separation layer is a composite structure, which comprises a plurality of layers of stainless steel wire mesh, a polytetrafluoroethylene film, a pressing plate and a support assembly. The plurality of layers of stainless steel wire mesh is provided with a layer of polytetrafluoroethylene film thereon, the polytetrafluoroethylene film is provided with a pressing plate thereon, and the plurality of layers of stainless steel wire mesh is provided with another pressing plate thereon, i.e. the pressing plate, the polytetrafluoroethylene film, the plurality of layers of stainless steel wire mesh and the other pressing plate are sequentially arranged from top to bottom to form a composite structure, and the two ends of the composite structure are fixed to the inner wall of the gas-liquid separation tank through the support assembly.

[0015] Further, the sparkless pneumatic diaphragm pump is connected with an electromagnetic valve and a bypass manual valve respectively; the diaphragm material of the sparkless pneumatic diaphragm pump is perfluoroether rubber, so as to avoid the reaction or adsorption of the diaphragm with high-value chemicals; and the inlet and outlet valves of the sparkless pneumatic diaphragm pump adopt a sanitary quick-mount structure.

[0016] Further, the liquid level meter adopts a plate-type liquid level meter, and the first and second liquid level switches output signals to control the opening and closing of the electromagnetic valve on the air pipeline of the sparkless pneumatic diaphragm pump.

[0017] A method for cleaning the cargo tank of an oil tanker and chemical tanker based on the above-mentioned cleaning system for the cargo tank of an oil tanker and chemical tanker, comprising the following steps: S1, starting the cleaning; The pneumatic jet pump is started, and the suction pipeline of the pneumatic jet pump gradually forms a vacuum pressure of-0.5 bar or above, the air / nitrogen in the cargo tank enters the scavenging pipe through the auxiliary suction hole of the scavenging pipe and mixes with the bottom liquid to form a gas-liquid mixed flow, and the pneumatic jet pump sucks the mixed flow into the gas-liquid separation tank; S2, gas-liquid separation; The gas-liquid mixture entering the gas-liquid separation tank is separated by the multi-layer composite structure of the gas-liquid separation layer. The liquid is settled at the bottom of the tank due to gravity, and the gas rises to the top and is ready to be discharged through the gas vent mast; S3, residual liquid transportation; After the gas-liquid separation, when the liquid level of the first liquid level switch in the gas-liquid separation tank reaches the set high liquid level threshold, the liquid level switch triggers a signal to open the electromagnetic valve on the air pipeline of the pneumatic diaphragm pump, and the pneumatic diaphragm pump is started to transport the residual liquid at the bottom of the gas-liquid separation tank to the header or the residual liquid tank; When the liquid level drops to the threshold of the second liquid level switch, the liquid level switch triggers a signal again to close the electromagnetic valve, and the pneumatic diaphragm pump stops working; After the delivery is completed, the pump body and the connecting pipeline can be cleaned by a special cleaning tool.

[0018] S4, air venting and discharging; The gas discharged from the top of the gas-liquid separation tank is connected to the air venting mast, and under the action of the fireproof net of the air venting mast, the gas is safely discharged at a high altitude to prevent the gas from accumulating in the deck area to form an explosive dangerous environment; S5, equipment maintenance and replacement; Periodically check the state of each component, replace the standby nozzle when the nozzle of the pneumatic jet pump is worn and affects the pumping efficiency, replace the standby separation layer assembly when the separation effect of the gas-liquid separation layer decreases, and replace the standby fixed small hole insert with a suitable aperture in a timely manner according to the change of the chemical properties, so that the system is always in the best operating state.

[0019] Compared with the prior art, the beneficial effects of the present application are: The present application provides a tank cleaning system and method for oil tankers and chemical tankers, which comprises a pneumatic jet pump, a tank cleaning pipe with auxiliary suction holes, a gas-liquid separation tank, a spark-free diaphragm pump and an air venting mast. The tank cleaning method reduces the residual liquid density by mixing gas, combines high vacuum suction and gas-liquid separation, and realizes single-tank residual liquid less than 20L; the whole process is free of mechanical contact pollution. The present application has the following advantages: (1) extremely low residual liquid volume: By introducing gas through the auxiliary suction holes on the tank cleaning pipe to reduce the liquid density, combined with the high vacuum suction capacity of the pneumatic jet pump, the liquid level difference of more than 10 meters in the tank can be effectively overcome, and the single-tank residual liquid is greatly reduced to not more than 20L, which is much lower than the requirement of 75L in the industry standard, greatly reducing the loss of high-value chemicals.

[0020] (2) zero pollution guarantee: The whole tank cleaning system is driven by full pneumatic and inert materials, the components in contact with the goods are made of high-purity and low-reactivity materials, and special cleaning tools and cleaning media are provided to avoid mechanical part wear debris, lubricating oil and secondary pollution in the cleaning process, meet the ISO 21487 health standard, and the purity of the goods is higher than 90%.

[0021] (3) high safety performance: The system of the present application uses a spark-free pneumatic diaphragm pump to transport residual liquid, eliminating the risk of electric spark, and at the same time, the gas is safely discharged at a high altitude through the air venting mast to reduce the concentration of flammable gas in the deck area, so that the concentration of oil and gas in the deck area is lower than the lower limit of explosion, greatly enhancing the safety and ensuring the safety of the ship.

[0022] (4) strong adaptability: The system of the present application supports cargo with viscosity not greater than 500 cP, improves the efficiency of cabin cleaning, can be flexibly adjusted according to the characteristics of high-value chemicals, can adapt to the cabin cleaning operation of various high-viscosity, high-purity and easily-oxidized high-value chemicals, and adopts a common plate type liquid level meter, thereby reducing the system cost and meeting the needs of crew to directly observe the liquid level. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the cabin cleaning system of the oil tanker and chemical tanker of the present application.

[0024] Figure 2 It is a structural schematic diagram of the gas-liquid separation tank of the cabin cleaning system of the present application.

[0025] Figure 3 It is an enlarged schematic diagram of the gas-liquid separation layer in the gas-liquid separation tank of the present application.

[0026] Figure 4 It is a cabin bottom cabin cleaning node diagram of the cabin cleaning system of the present application.

[0027] Figure 5 It is a structural schematic diagram of the pneumatic jet pump of the present application.

[0028] Figure 6 It is a structural schematic diagram of the sparkless pneumatic diaphragm pump of the present application.

[0029] Figure 7 It is a flow schematic diagram of the cabin cleaning method of the cabin cleaning system of the oil tanker and chemical tanker of the present application.

[0030] Wherein: cabin cleaning pipe 1, auxiliary suction hole 1.1, cargo oil pump 2, pneumatic jet pump 3, gas-liquid separation tank 4, gas-liquid separation layer 4.1, multilayer stainless steel wire mesh 4.11, polytetrafluoroethylene film 4.12, pressing plate 4.13, support assembly 4.14, liquid level meter 4.2, thermometer 4.3, first liquid level switch 4.4, second liquid level switch 4.5, sparkless pneumatic diaphragm pump 5, electromagnetic valve 5.1, bypass manual valve 5.2, air permeable mast 6. DETAILED DESCRIPTION

[0031] In order to better understand the technical solutions of the present application, the following will be described in detail in combination with relevant drawings. It should be understood that the following specific examples are not intended to limit the specific implementation manners of the technical solutions of the present application, and they are only implementation manners that can be adopted by the technical solutions of the present application. It should be noted that the expressions about the positional relationship of each component in this paper, such as that the A component is located above the B component, are based on the expressions about the relative positions of each component in the drawings, and are not intended to limit the actual positional relationship of each component. Example 1

[0032] Referring to Figures 1-6 ,Figure 1 The drawing is a structural schematic diagram of a tank cleaning system of an oil and chemical tanker of the present application. As shown in the drawing, the tank cleaning system of an oil and chemical tanker of the present application is arranged in the main deck area of the ship, each cargo tank on the main deck is provided with a cargo oil pump 2, and the tank cleaning system of an oil and chemical tanker comprises a tank cleaning pipe system, a pneumatic jet pump 3, a gas-liquid separation tank 4 and a sparkless pneumatic diaphragm pump 5; the tank cleaning pipe system comprises a plurality of tank cleaning pipes 1, and each cargo oil pump 2 is matched with a tank cleaning pipe 1, one end of the tank cleaning pipe 1 extends into the oil suction well position at the bottom of the corresponding cargo oil pump 2, and the other end is connected to the pneumatic jet pump 3.

[0033] The tank cleaning pipe 1 is provided with an auxiliary suction hole 1.1, the auxiliary suction hole 1.1 is 0.8m~1.5m away from the bottom end of the tank cleaning pipe 1, the tank cleaning pipe 1 is made of 316L stainless steel pipe or inner lining polytetrafluoroethylene, the inner wall of the tank cleaning pipe 1 is provided with mirror polishing treatment, the inner wall roughness Ra≤0.8μm, and the attachment and residue of high-value chemicals on the pipe wall are reduced; the auxiliary suction hole 1.1 is opened by laser drilling process, the hole diameter of the auxiliary suction hole 1.1 is 1 / 20 to 1 / 30 of the inner diameter of the tank cleaning pipe 1, the hole diameter accuracy of the auxiliary suction hole 1.1 is controlled within ±0.02mm, the gas mixing amount is stable, and the suction efficiency fluctuation and cargo residue increase caused by hole diameter error are avoided. When the pneumatic jet pump 3 works, external air (or nitrogen) enters the tank cleaning pipe 1 through the auxiliary suction hole 1.1, mixes with the liquid in the tank cleaning pipe 1, reduces the liquid density, and thus the liquid is more easily pumped to the main deck area, effectively overcoming the liquid level difference of more than 10 meters in the tank.

[0034] The suction pipe of the pneumatic jet pump 3 is connected to the tank cleaning pipe 1 of each cargo tank, the pneumatic jet pump 3 is driven by full pneumatic, air driving or nitrogen driving can be selected according to the characteristics of the cargo, and pollution to the cargo is avoided; the contact part of the pneumatic jet pump 3 with the cargo is made of corrosion-resistant and low-adsorption materials such as hastelloy or polytetrafluoroethylene, reducing the residue and adsorption of the cargo on the surface of the pump body.

[0035] The output end of the pneumatic jet pump 3 is connected to the gas-liquid separation tank 4, the gas-liquid separation tank 4 is arranged on the main deck, the gas-liquid separation tank 4 is provided with a gas-liquid separation layer 4.1, a liquid level meter 4.2, a thermometer 4.3, a first liquid level switch 4.4 and a second liquid level switch 4.5, the gas-liquid separation layer 4.1 is arranged at the upper part in the gas-liquid separation tank 4, the first liquid level switch 4.4 is arranged at the middle part of the gas-liquid separation tank 4, and the second liquid level switch 4.5 is arranged at the lower part in the gas-liquid separation tank 4; The inner surface of the gas-liquid separation tank 4 is treated by electrolytic polishing to reduce the liquid residue dead angle, and the material is selected to be the same as the corrosion-resistant and low-adsorption material of the tank cleaning pipe 1; The gas-liquid separation layer 4.1 is a composite structure, comprising a plurality of layers of stainless steel wire mesh 4.11, a polytetrafluoroethylene film 4.12, a pressing plate 4.13 and a support assembly 4.14, the plurality of layers of stainless steel wire mesh 4.11 is provided with a layer of polytetrafluoroethylene film 4.12, the polytetrafluoroethylene film 4.12 is provided with a pressing plate 4.13, the plurality of layers of stainless steel wire mesh 4.11 is provided with another pressing plate 4.13, that is, the pressing plate 4.13, the polytetrafluoroethylene film 4.12, the plurality of layers of stainless steel wire mesh 4.11 and the other pressing plate 4.13 are sequentially arranged from top to bottom to form a composite structure, and the composite structure is fixed to the inner wall of the gas-liquid separation cabinet 4 through the support assembly 4.14 at both ends; the gas-liquid separation layer 4.1 is composed of a plurality of layers of stainless steel wire mesh and a polytetrafluoroethylene film, which improves the gas-liquid separation efficiency and reduces the entrainment loss of high-value chemical vapor; The top of the gas-liquid separation cabinet 4 is connected to the gas venting mast 6 in a breathable manner, since the separated gas contains a high concentration of oil and gas mixture, according to relevant specifications, the gas is discharged through the gas venting mast at a high altitude to reduce the concentration of flammable gas in the deck area and ensure the safety of the ship.

[0036] The suction port of the sparkless pneumatic diaphragm pump 5 is connected to the gas-liquid separation cabinet 4, the discharge port of the sparkless pneumatic diaphragm pump 5 is connected to the header or the residual liquid tank, the sparkless pneumatic diaphragm pump 5 is connected to the electromagnetic valve 5.1 and the bypass manual valve 5.2 respectively; the diaphragm material of the sparkless pneumatic diaphragm pump 5 is perfluoroether rubber, which avoids reaction or adsorption of the diaphragm with high-value chemicals; the inlet and outlet valves of the sparkless pneumatic diaphragm pump 5 adopt a sanitary quick-mount structure, which is convenient for disassembly and cleaning, reduces residue, and is equipped with a spare diaphragm; When the liquid level in the gas-liquid separation cabinet 4 reaches the set value, the sparkless pneumatic diaphragm pump 5 starts to transport the separated liquid to the header or the residual liquid tank, ensuring the safety of the transportation process, especially suitable for the case of high mixing of oil and gas.

[0037] The liquid level meter 4.2 adopts a common plate type liquid level meter, which is convenient for the crew to directly observe the change of the liquid level; the first liquid level switch 4.4 and the second liquid level switch 5.5 can remind the crew of the tank liquid level and can output signals to control the opening and closing of the electromagnetic valve 5.1 on the air pipeline driven by the sparkless pneumatic diaphragm pump 5.

[0038] The diameter of the tank cleaning pipe 1 is selected according to the size of the cabin, DN25 or above can be selected for large oil tankers and chemical tankers, and DN25 or below can be selected for small chemical tankers, the smaller the pipe, the better the result after tank cleaning, but the simultaneous tank cleaning time will increase.

[0039] Referring to Figures 1-7 , Figure 7The diagram illustrates a flow chart of the tank sweeping method for the tanker / chemical tanker sweeping system of the present invention. As shown, the tank sweeping method of the tanker / chemical tanker sweeping system of the present invention, based on the aforementioned tanker / chemical tanker sweeping system, includes the following: S1. Cabin sweeping initiated; Start the pneumatic jet pump. The pneumatic jet pump suction pipe gradually forms a vacuum pressure of -0.5 bar or higher. The air / nitrogen in the cargo hold enters the sweep pipe through the auxiliary suction port of the sweep pipe and mixes with the residual liquid at the bottom of the hold to form a gas-liquid mixture. The pneumatic jet pump draws the mixture to the gas-liquid separator. S2, gas-liquid separation; The gas-liquid mixture entering the gas-liquid separator undergoes efficient separation through the multi-layered composite structure of the gas-liquid separation layer. The liquid settles to the bottom of the separator due to gravity, while the gas rises to the top, ready to be discharged through the vent mast. S3, residual liquid transport; After gas-liquid separation, when the liquid level of the first liquid level switch in the gas-liquid separation cabinet reaches the set high liquid level threshold (such as when the liquid level reaches 50% of the cabinet capacity), the liquid level switch triggers a signal to open the solenoid valve on the air pipeline driven by the pneumatic diaphragm pump. The pneumatic diaphragm pump starts and transports the residual liquid at the bottom of the gas-liquid separation cabinet to the manifold area or residual liquid compartment. When the liquid level drops to the threshold of the second liquid level switch (e.g., the liquid level drops to 20%), the liquid level switch triggers a signal again, closing the solenoid valve and stopping the pneumatic diaphragm pump. After the delivery is completed, the pump body and connecting pipelines can be cleaned using special cleaning tools.

[0040] S4, breathable ventilation; The gas discharged from the top of the gas-liquid separator is safely discharged at high altitude through a pipe connected to the venting mast, under the action of the fireproof net of the venting mast, to prevent the gas from accumulating in the deck area and forming an explosive atmosphere. S5. Equipment maintenance and replacement; Regularly check the condition of each component. When the pneumatic jet pump nozzle wears down and affects the suction efficiency, replace it with a spare nozzle. When the separation effect of the gas-liquid separation layer decreases, replace it with a spare separation layer component. According to changes in the properties of chemicals, replace the spare fixing small hole plug with the appropriate orifice size in a timely manner to ensure that the system is always in the best operating condition.

[0041] Specific implementation examples: Taking the transport of caustic soda by an 83,500 CBC ship as an example: 1. System Configuration: Scanning tube: 316L stainless steel, inner diameter 40mm, small hole φ1.6mm (laser drilling); Jet pump: PTFE contact parts; Gas-liquid separator: Alkali-resistant rubber lining, PTFE composite separation layer.

[0042] 2. Operation flow: The pneumatic jet pump is started to create a high vacuum environment, and the cabin air is mixed with the caustic soda residual liquid (viscosity 200 cP) at the bottom of the cargo tank through a small hole to form a gas-liquid mixed flow with a gas-liquid ratio of 1:3; Due to the certain viscosity of the caustic soda solution, the mixing of the gas effectively reduces the density of the liquid, so that the mixed flow is smoothly lifted 20 meters along the scavenging pipe under the suction of the pneumatic jet pump and is transported to the gas-liquid separation tank on the main deck; After entering the gas-liquid separation tank, the gas-liquid mixture is quickly separated under the action of the separation layer, and the caustic soda residual liquid settles at the bottom of the tank, and the separated gas (containing a small amount of water vapor and air) is discharged at a high altitude through the air permeable mast. When the panel liquid level meter on the gas-liquid separation tank shows that the liquid level reaches 50% of the tank capacity, the liquid level switch triggers a signal to open the air solenoid valve driven by the pneumatic diaphragm pump (the diaphragm material is perfluoroether rubber, which is resistant to strong alkali corrosion). The pump starts to stably transport the separated caustic soda residual liquid to the residual liquid tank. When the liquid level drops to 20% of the tank capacity, the liquid level switch triggers a signal again to drive the air solenoid valve to close and stop the diaphragm pump; After the transportation is completed, special cleaning tools (endoscope cleaning brushes and high-pressure spray heads that fit the pipeline) are used to flush the pump body and connecting pipeline, and alkaline solvent is used to flush the pipeline to avoid residual caustic soda crystallization and block the pipeline.

[0043] 3. Effect verification: Residual liquid amount: After entering the cabin, there is no visible residual liquid at the bottom of the oil suction well and the inlet of the super scavenging pipe, achieving the effect of "no residual liquid at the bottom of the oil suction well"; Operation time: The entire scavenging process only takes 45 minutes, which is significantly efficient; There is no corrosion and leakage phenomenon, which verifies the high efficiency and reliability of the scavenging system of the present application in the scavenging operation of chemical and bulk cargo ships and strongly corrosive cargo.

[0044] Working principle: The present application provides a scavenging system and method for oil tankers and chemical tankers, and the core components of the scavenging system are: (1) Pneumatic jet pump assembly: Driving medium: air / nitrogen (explosion-proof switching); Contact material: hastelloy or polytetrafluoroethylene (corrosion-resistant and low adsorption); Function: >90kPa vacuum is generated by Venturi effect, high vacuum is generated by Venturi effect, and the bottom cargo can be effectively pumped.

[0045] (2) Scavenging pipe system: Extended to the bottom of the oil suction well; Laser drilling (aperture accuracy ±0.02mm) is arranged 1 meter from the bottom of the cabin; The ratio of the small hole diameter to the inner diameter of the pipe is 1:20~1:30 (optimizing gas-liquid mixing efficiency); Material: 316L stainless steel, inner wall mirror polishing (Ra≤0.8μm).

[0046] (3) Gas-liquid separation cabinet: Separation structure: 200-mesh stainless steel wire mesh + polytetrafluoroethylene membrane composite layer; Inner wall electrolytic polishing; Equipped with plate type liquid level meter and liquid level switch (linkage control); Liquid level switch threshold: high liquid level 50% of the tank capacity / low liquid level 20% of the tank capacity (precise control of pump start and stop).

[0047] (4) Spark-free pneumatic diaphragm pump: Diaphragm material: perfluoroether rubber (resistant to chemical corrosion); Valve: sanitary quick-mount structure.

[0048] (5) Air permeation system: Connected to the air permeation mast with built-in fireproof net (fire resistance ≤10ms).

[0049] Its method of cleaning the cabin includes: (1) Cleaning the cabin start-up stage: start the pneumatic jet pump, select air or nitrogen according to the characteristics of high-value chemicals, and enter the pipe through the fixed small hole or the spare fixed small hole insert about 1 meter from the bottom of the cabin. The hole mixes with the goods at the bottom of the cargo hold to form a gas-liquid mixed flow, and is sucked into the gas-liquid separation cabinet; (2) Gas-liquid separation stage: the gas-liquid mixture is separated in the gas-liquid separation layer in the gas-liquid separation cabinet, the liquid settles at the bottom of the cabinet, and the gas rises to the top ready for discharge; (3) Residual liquid transport stage: when the liquid level of the gas-liquid separation cabinet reaches the set high liquid level threshold through the plate type liquid level meter, the liquid level switch triggers a signal to start the pneumatic diaphragm pump, which transports the residual liquid to the manifold area or the residual liquid cabin. When the liquid level drops to the low liquid level threshold, the liquid level switch triggers a signal to turn off the pneumatic diaphragm pump, and after the transport is completed, the relevant parts are cleaned with special cleaning tools; The set high liquid level threshold is 50% of the volume of the gas-liquid separation cabinet, and the low liquid level threshold is 20% of the volume of the gas-liquid separation cabinet; (4) Air permeation discharge stage: the gas discharged from the top of the gas-liquid separation cabinet is safely discharged at high altitude through the air permeation mast; (5) Spare parts maintenance and replacement stage: regularly check each part, and replace the spare pneumatic jet pump nozzle or spare gas-liquid separation layer assembly as needed.

[0050] The above are only specific application examples of the present application, and do not constitute any limitation on the protection scope of the present application. Any technical solution formed by equivalent transformation or equivalent replacement falls within the protection scope of the present application.

Claims

1. A tank cleaning system for a combination oil and chemical tanker, characterized in that: The application relates to a cargo tank cleaning system for a ship, which is arranged in a main deck area of the ship, and each cargo tank on the main deck is provided with a cargo oil pump (2). The cargo tank cleaning system comprises a cargo tank cleaning pipe system, an air injection pump (3), a gas-liquid separation tank (4) and a sparkless air diaphragm pump (5). The cargo tank cleaning pipe system comprises a plurality of cargo tank cleaning pipes (1), and the cargo oil pump (2) of each cargo tank is matched with a cargo tank cleaning pipe (1). One end of the cargo tank cleaning pipe (1) extends into the oil suction well position at the bottom of the corresponding cargo oil pump (2), and the other end is connected to the air injection pump (3). An auxiliary suction hole (1.1) is arranged on the cargo tank cleaning pipe (1). The suction pipe of the air injection pump (3) is connected to the cargo tank cleaning pipe (1) of each cargo tank, and the air injection pump (3) is driven by full air. The output end of the air injection pump (3) is connected to the gas-liquid separation tank (4), and the gas-liquid separation tank (4) is arranged on the main deck. The gas-liquid separation tank (4) is provided with a gas-liquid separation layer (4.1), a liquid level meter (4.2), a thermometer (4.3), a first liquid level switch (4.4) and a second liquid level switch (4.5). The gas-liquid separation layer (4.1) is arranged at the upper part in the gas-liquid separation tank (4). The first liquid level switch (4.4) is arranged at the middle part of the gas-liquid separation tank (4). The second liquid level switch (4.5) is arranged at the lower part in the gas-liquid separation tank (4). The top of the gas-liquid separation tank (4) is connected to a gas permeation mast (6) in a gas permeation mode. The suction inlet of the sparkless air diaphragm pump (5) is connected to the gas-liquid separation tank (4), and the discharge outlet of the sparkless air diaphragm pump (5) is connected to a manifold area or a residual liquid tank.

2. A tank cleaning system for a combination oil and chemical tanker according to claim 1, characterized in that: The auxiliary suction hole (1.1) is 0.8m-1.5m away from the bottom end of the cargo tank cleaning pipe (1).

3. A tank cleaning system for a combination oil and chemical tanker according to claim 1, characterized in that: The cargo tank cleaning pipe (1) is made of a 316L stainless steel pipe or a polytetrafluoroethylene lining.

4. A tank cleaning system for a combination oil and chemical tanker according to claim 1, characterized in that: The inner wall of the cargo tank cleaning pipe (1) is provided with mirror polishing treatment, and the roughness of the inner wall is not greater than 0.8mu m, so that the attachment and residue of high-value chemicals on the pipe wall are reduced.

5. A tank cleaning system for a combination oil and chemical tanker according to claim 1, characterized in that: The aperture of the auxiliary suction hole (1.1) is 1 / 20-1 / 30 of the inner diameter of the cargo tank cleaning pipe (1), and the aperture accuracy of the auxiliary suction hole (1.1) is controlled to be plus or minus 0.02mm, so that the gas mixing amount is stable, and the suction efficiency fluctuation and the cargo residue increase caused by the aperture error are avoided.

6. A tank cleaning system for a combination oil and chemical tanker according to claim 1, characterized in that: The contact part of the air injection pump (3) with the cargo is made of a corrosion-resistant and low-adsorption material, such as a hastelloy or polytetrafluoroethylene. The inner surface of the gas-liquid separation tank (4) is subjected to electrolytic polishing treatment, so that the liquid residue dead angle is reduced, and the corrosion-resistant and low-adsorption material same as the cargo tank cleaning pipe (1) is selected.

7. A tank cleaning system for a combination oil and chemical tanker according to claim 1, characterized in that: The gas-liquid separation layer (4.1) is a composite structure including a plurality of layers of stainless steel wire mesh (4.11), a polytetrafluoroethylene film (4.12), a pressing plate (4.13) and a support assembly (4.14), a layer of polytetrafluoroethylene film (4.12) is arranged above the plurality of layers of stainless steel wire mesh (4.11), a pressing plate (4.13) is arranged above the polytetrafluoroethylene film (4.12), another pressing plate (4.13) is arranged below the plurality of layers of stainless steel wire mesh (4.11), i.e. the pressing plate (4.13), the polytetrafluoroethylene film (4.12), the plurality of layers of stainless steel wire mesh (4.11) and the other pressing plate (4.13) are sequentially arranged from top to bottom to form the composite structure, and the two ends of the composite structure are fixed to the inner wall of the gas-liquid separation cabinet (4) through the support assemblies (4.14).

8. A tank cleaning system for a combination oil and chemical tanker according to claim 1, characterized in that: The sparkless pneumatic diaphragm pump (5) is connected with the electromagnetic valve (5.1) and the bypass manual valve (5.2) respectively; the diaphragm material of the sparkless pneumatic diaphragm pump (5) is perfluoroether rubber, and the inlet and outlet valves of the sparkless pneumatic diaphragm pump (5) adopt a sanitary quick-mounting structure.

9. A tank cleaning system for a combination oil and chemical tanker according to claim 1, characterized in that: The liquid level meter (4.2) adopts a plate-type liquid level meter, and the first liquid level switch (4.4) and the second liquid level switch (4.5) output signals to control the opening and closing of the electromagnetic valve (5.1) on the air line driven by the sparkless pneumatic diaphragm pump (5).

10. A method of purging a cargo tank of a combination oil / chemical tanker according to claim 1, characterized in that The following is included: S1, start of cabin cleaning; Start the pneumatic jet pump, and the air or nitrogen in the cargo hold enters the cleaning pipe through the auxiliary suction hole of the cleaning pipe, mixes with the residual liquid at the bottom of the hold to form a gas-liquid mixed flow, and the pneumatic jet pump sucks the mixed flow into the gas-liquid separation cabinet; S2, gas-liquid separation; The gas-liquid mixture entering the gas-liquid separation cabinet is efficiently separated by the multi-layer composite structure of the gas-liquid separation layer. The liquid settles at the bottom of the cabinet due to gravity, and the gas rises to the top, ready to be discharged through the gas vent mast; S3, residual liquid transportation; After gas-liquid separation, when the liquid level of the first liquid level switch in the gas-liquid separation cabinet reaches the set high liquid level threshold, the liquid level switch triggers a signal to open the electromagnetic valve on the air line driven by the pneumatic diaphragm pump, and the pneumatic diaphragm pump starts to transport the residual liquid at the bottom of the gas-liquid separation cabinet to the header zone or the residual liquid tank; When the liquid level drops to the threshold of the second liquid level switch, the liquid level switch triggers a signal again to close the electromagnetic valve, and the pneumatic diaphragm pump stops working; After the transportation is completed, the pump body and the connecting pipeline can be cleaned by using special cleaning tools; S4, gas venting; The gas discharged from the top of the gas-liquid separation cabinet is connected to the pipeline of the gas vent mast, and under the action of the fireproof net of the gas vent mast, it is safely discharged at a high altitude; S5, equipment maintenance and replacement; Regularly check the status of each component, replace the spare nozzle when the nozzle of the pneumatic jet pump is worn and affects the suction efficiency, replace the spare separation layer assembly when the separation effect of the gas-liquid separation layer decreases, and replace the spare fixed small hole insert with a suitable aperture in a timely manner according to the changes in chemical properties, to ensure that the system is always in the best operating state.

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