Dehydration system of liquefied hydrocarbon tank

Abstract

The invention discloses a liquefied hydrocarbon tank dehydration system to solve the problems that in the prior art, a liquefied hydrocarbon tank dehydration system is poor in dehydration effect and cannot be reliably closed in time when liquefied hydrocarbon leaks. The device comprises a dehydration pipe, a secondary dehydration tank, a blow-off pipe, a gas phase balance pipeline, a liquefied hydrocarbon liquid phase header pipe, a torch blow-off pipeline and a secondary dehydration tank blow-off pipe, the liquefied hydrocarbon liquid phase header pipe comprises a horizontal section liquid phase header pipe and a vertical section liquid phase header pipe, and the top end of the vertical section liquid phase header pipe is communicated to the bottom of the liquefied hydrocarbon tank; the bottom end of the vertical section liquid-phase header pipe is communicated with one end of the horizontal section liquid-phase header pipe, the vertical section liquid-phase header pipe is provided with a liquid-phase header pipe tank root ESD valve, the horizontal section liquid-phase header pipe is provided with a liquefied hydrocarbon liquid-phase extraction valve, an inlet of the dewatering pipe is connected to the position under the horizontal section of the liquefied hydrocarbon liquid-phase header pipe, and an outlet of the dewatering pipe is connected to the secondary dewatering tank. A sampler is arranged between the dewatering pipe inlet and the dewatering pipe operating valve, a water discharging pipe is led out of an opening in the center of the bottom of the secondary dewatering tank and led to a sewage system, and a gas phase balance pipeline is led between the secondary dewatering tank safety valve and the secondary dewatering tank gas phase outlet to be connected to a liquefied hydrocarbon tank safety valve inlet pipeline.

Description

Technical Field

[0001] This invention belongs to the field of oil storage and transportation safety technology for petrochemical enterprises, and specifically relates to a dehydration system for liquefied hydrocarbon tanks. Background Technology

[0002] In existing petrochemical enterprises, liquefied hydrocarbons are mostly stored in full-pressure storage tanks (spherical tanks and horizontal tanks). If the liquefied hydrocarbons contain water, the liquefied hydrocarbon tanks use a secondary dehydration system for dehydration. The commonly used dehydration method is as follows: a dehydration port is set at the bottom of the liquefied hydrocarbon tank (or on the manhole cover at the bottom of the tank), a dehydration pipe is led out from the dehydration port, and a dehydration pipe tank root valve is set near the dehydration port. Operators can directly carry out dehydration operations by opening the dehydration pipe tank root valve and the dehydration pipe operating valve, or a secondary dehydration tank is used for dehydration operations.

[0003] Patent CN110499184A discloses a dehydration device for a liquefied hydrocarbon tank, which comprises a liquefied hydrocarbon tank, a secondary dehydration tank, a float sealing ball mechanism, a dehydration pipe, a liquid phase return pipe, a gas phase balance pipe, a liquefied hydrocarbon flare venting pipe, a dehydration tank flare venting pipe, a liquefied hydrocarbon safety valve inlet pipe, a dehydration tank safety valve inlet pipe, a gas phase venting pipe, and a drain pipe. The bottom of the liquefied hydrocarbon tank is equipped with a dehydration pipe connected to the secondary dehydration tank; the top of the liquefied hydrocarbon tank is equipped with a liquefied hydrocarbon safety valve, one end of which is connected to the liquefied hydrocarbon safety valve inlet pipe to the liquefied hydrocarbon tank, and the other end is connected to the liquefied hydrocarbon flare venting pipe. The secondary dehydration tank is equipped with a dehydration tank safety valve on its top. One end of the dehydration tank safety valve is connected to the inlet pipe of the dehydration tank safety valve to the secondary dehydration tank, and the other end is connected to the dehydration tank flare pipe to the liquefied hydrocarbon flare vent pipe. A liquid phase return pipe is installed between the dehydration pipe and the dehydration tank safety valve inlet pipe. A gas phase balance pipe is installed between the liquefied hydrocarbon safety valve inlet pipe and the dehydration tank safety valve inlet pipe. A gas phase venting pipe is installed between the dehydration tank safety valve inlet pipe and the liquefied hydrocarbon flare vent pipe. A drain pipe is installed at the bottom of the secondary dehydration tank, and a float sealing ball mechanism is installed at the outlet of the drain pipe.

[0004] The existing liquefied hydrocarbon tank dehydration system has the following drawbacks: 1. Water in the liquefied hydrocarbon liquid phase main pipe cannot be completely removed, which can easily lead to quality accidents. Because the ESD valve at the root of the liquefied hydrocarbon liquid phase main pipe is normally open and the liquefied hydrocarbon liquid phase extraction valve is closed, the liquefied hydrocarbon liquid phase main pipe between the liquefied hydrocarbon liquid phase extraction valve and the liquefied hydrocarbon tank is connected to the liquefied hydrocarbon tank and is the lowest point of the entire system. Water from the liquefied hydrocarbon tank during the receiving process will accumulate in this section of the liquefied hydrocarbon liquid phase main pipe. The existing liquefied hydrocarbon tank dehydration system cannot remove the water in the liquefied hydrocarbon liquid phase main pipe, and the liquefied hydrocarbon containing water will be sent to the user, causing a quality accident at the factory; 2. The dehydration system cannot shut off the liquefied hydrocarbon leak in a timely and reliable manner. Summary of the Invention

[0005] The purpose of this invention is to provide a dehydration system for liquefied hydrocarbon tanks to solve the problems of poor dehydration effect and inability to shut off liquefied hydrocarbon leaks in a timely and reliable manner in the prior art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A liquefied hydrocarbon tank dehydration system includes a liquefied hydrocarbon tank, a dehydration pipe, a secondary dehydration tank, a drain pipe, a gas phase balance pipe, a liquefied hydrocarbon liquid phase main pipe, a flare vent pipe, and a secondary dehydration tank vent pipe. The system is characterized in that: the top of the liquefied hydrocarbon tank is equipped with a liquefied hydrocarbon tank safety valve inlet pipe, which is connected to the flare vent pipe; a liquefied hydrocarbon tank safety valve is installed on the liquefied hydrocarbon tank safety valve inlet pipe; the liquefied hydrocarbon liquid phase main pipe includes a horizontal section and a vertical section. The top of the vertical liquid phase manifold connects to the bottom of the liquefied hydrocarbon tank. The bottom of the vertical liquid phase manifold connects to one end of the horizontal liquid phase manifold, and the other end of the horizontal liquid phase manifold connects to the pump inlet. The vertical liquid phase manifold is equipped with a tank-root ESD valve, and the horizontal liquid phase manifold is equipped with a liquefied hydrocarbon liquid phase extraction valve. The dehydration pipe includes a dehydration pipe inlet and a dehydration pipe outlet. The dehydration pipe inlet is connected directly below the horizontal section of the liquefied hydrocarbon liquid phase manifold, with the connection point located between the liquefied hydrocarbon liquid phase extraction valve and the tank-root ESD valve of the liquid phase manifold. A liquid phase extraction valve for liquefied hydrocarbons is preferably installed with its connection point as close as possible to the liquefied hydrocarbon liquid phase extraction valve; a dehydration pipe operating valve is installed on the dehydration pipe near the dehydration pipe inlet, and the dehydration pipe outlet is connected to the secondary dehydration tank; a sampler is installed between the dehydration pipe inlet and the dehydration pipe operating valve; a drain pipe is led out from the center of the bottom of the secondary dehydration tank, and a secondary dehydration tank drain pipe root valve is installed near the secondary dehydration tank; the drain pipe leads to the wastewater system; a gas phase outlet for the secondary dehydration tank is installed at the top of the secondary dehydration tank. A vent pipe from the secondary dehydration tank's gas phase outlet is connected to the flare vent pipe. A safety valve for the secondary dehydration tank is installed on the vent pipe. A gas phase balance pipe is connected between the safety valve and the gas phase outlet of the secondary dehydration tank and then to the inlet pipe of the safety valve for the liquefied hydrocarbon tank. A gas phase balance pipe connecting valve is installed on the gas phase balance pipe near the secondary dehydration tank. An insertion-type intelligent electric float level gauge is installed on the top of the secondary dehydration tank. A magnetic float level gauge is installed in an easily observable location on the secondary dehydration tank.

[0008] The present invention discloses a dehydration system for a liquefied hydrocarbon tank, the further technical feature of which is that the insertion depth h1 of the insertion type intelligent electric float level gauge into the secondary dehydration tank is the distance from the bottom of the secondary dehydration tank, and h1 is 50mm to 250mm.

[0009] The present invention discloses a dehydration system for a liquefied hydrocarbon tank, the further technical feature of which is that the low liquid level value of the magnetic float level gauge is 50mm to 150mm lower than the low alarm value of the intelligent electric float level gauge.

[0010] The present invention discloses a dehydration system for a liquefied hydrocarbon tank, the further technical feature of which is that the dehydration pipe enters the secondary dehydration tank step by step at a low angle, that is, it slopes from the inlet of the dehydration pipe to the outlet of the dehydration pipe, with a slope i of 0.002 to 0.05, to avoid the formation of concave bags in the dehydration pipe.

[0011] The present invention discloses a dehydration system for a liquefied hydrocarbon tank, wherein the dehydration pipe outlet is connected to a secondary dehydration tank, and the distance h2 between the top of the dehydration pipe outlet and the weld of the upper end cap is 100mm to 200mm.

[0012] The present invention discloses a dehydration system for a liquefied hydrocarbon tank, further characterized in that the liquefied hydrocarbon tank dehydration system also includes a spring valve, which is disposed between the sewage system and the root valve of the secondary dehydration tank drain pipe.

[0013] The present invention discloses a dehydration system for a liquefied hydrocarbon tank, the further technical feature of which is that the horizontal section of the liquid phase main pipe has a certain slope, the slope i is 0.002 to 0.05, and the slope direction is from the ESD valve side of the liquid phase main pipe tank root to the liquefied hydrocarbon liquid phase extraction valve side.

[0014] The present invention discloses a dehydration system for a liquefied hydrocarbon tank, the further technical feature of which is that the ESD valve at the root of the liquid phase main pipe is an emergency shut-off valve with remote and local control functions, as well as failure prevention and fire prevention functions.

[0015] The present invention discloses a dehydration system for a liquefied hydrocarbon tank, further characterized in that: a secondary dehydration tank is arranged below the liquefied hydrocarbon tank and is located close to the inlet of the dehydration pipe. The length of the dehydration pipe is minimized; the 0-level alarm value of the intelligent electric float level gauge on the secondary dehydration tank is set to 250mm-350mm, and the 100-level alarm value is the center height of the dehydration pipe outlet.

[0016] The present invention discloses a dehydration system for a liquefied hydrocarbon tank, the further technical feature of which is that the wastewater entering the wastewater system is first filtered before entering the wastewater system, and the filtration device is a funnel.

[0017] This invention discloses a dehydration system for liquefied hydrocarbon tanks, primarily used for dehydration systems of pressure-stored liquid C3, C4, and their mixtures. Its advantages over existing technologies are as follows: This invention's liquefied hydrocarbon tank dehydration system sets a dehydration pipe inlet directly below the liquid phase operating valve side of the liquefied hydrocarbon liquid phase main pipe, completely differing from existing methods that set dehydration ports at the bottom of the liquefied hydrocarbon tank (or on the manhole cover at the bottom of the tank). This not only reduces the construction cost of a tank opening, lowering risks and costs, but also, by installing a sampler on the dehydration pipe, accurately determines whether the liquefied hydrocarbon liquid phase main pipe contains water, enabling timely dehydration operations and effectively preventing quality accidents caused by water content in the liquefied hydrocarbons upon delivery. Furthermore, the safety of the dehydration operation is ensured by the ESD valve at the root of the liquid phase main pipe.

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but this does not limit the scope of the invention. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a dehydration system for a liquefied hydrocarbon tank according to the present invention.

[0020] The reference numerals in the figure are:

[0021] 1-Dehydration pipe, 2-Secondary dehydration tank, 3-Water discharge pipe, 4-Liquid phase main pipe tank root ESD valve, 5-Dehydration pipe operating valve, 6-Secondary dehydration tank water discharge pipe tank root valve, 7-Spring valve, 8-Liquefied hydrocarbon tank, 9-Gas phase balance pipeline, 10-Liquefied hydrocarbon liquid phase main pipe, 11-Gas phase balance pipeline connecting valve, 12-Flame venting pipeline, 13-Secondary dehydration tank venting pipe, 14-Secondary dehydration tank safety valve, 15-Liquefied hydrocarbon liquid phase extraction valve, 16-Dehydration pipe inlet, 17-Dehydration pipe outlet, 18-Secondary dehydration tank gas phase outlet, 19-Intelligent electric float level gauge, 20-Magnetic float level gauge, 21-Manual venting valve, 22-Liquefied hydrocarbon tank safety valve, 23-Sampler, 24-Pump, 25-Process unit, 26-Liquefied hydrocarbon liquid phase collection valve, 27-Liquefied hydrocarbon liquid phase collection pipe. Detailed Implementation

[0022] like Figure 1As shown, a liquefied hydrocarbon tank dehydration system includes a dehydration pipe 1, a secondary dehydration tank 2, a drain pipe 3, a liquid phase main pipe tank root ESD valve 4, a dehydration pipe operating valve 5, a secondary dehydration tank drain pipe tank root valve 6, a spring valve 7, a liquefied hydrocarbon tank 8, a gas phase balance pipeline 9, a liquefied hydrocarbon liquid phase main pipe 10, a gas phase balance pipeline connecting valve 11, a flare vent pipeline 12, a secondary dehydration tank vent pipe 13, a secondary dehydration tank safety valve 14, a liquefied hydrocarbon liquid phase extraction valve 15, a dehydration pipe inlet 16, a dehydration pipe outlet 17, a secondary dehydration tank gas phase outlet 18, an intelligent electric float level gauge 19, a magnetic float level gauge 20, and a manual vent valve 21. The system includes a liquefied hydrocarbon tank safety valve 22, a sampler 23, a pump 24, a process unit 25, a liquefied hydrocarbon liquid phase collection valve 26, and a liquefied hydrocarbon liquid phase collection pipe 27. The top of the liquefied hydrocarbon tank 8 is equipped with a liquefied hydrocarbon tank safety valve inlet pipeline, which connects to a flare vent pipe 12, which leads to a flare. A liquefied hydrocarbon tank safety valve 22 is installed on the liquefied hydrocarbon tank safety valve inlet pipeline. The liquefied hydrocarbon liquid phase main pipe 10 includes a horizontal section and a vertical section. The top of the vertical section connects to the bottom of the liquefied hydrocarbon tank 8, and the bottom of the vertical section connects to one end of the horizontal section. The other end of the main phase pipe is connected to the inlet of pump 24. Process unit 25 is connected to the liquefied hydrocarbon liquid phase main pipe 10 through liquefied hydrocarbon liquid phase collection pipe 27. The connection point is close to the dehydration pipe inlet 16 and is located on the horizontal section of the liquefied hydrocarbon liquid phase main pipe 10 between the dehydration pipe inlet 16 and the ESD valve 4 at the bottom of the liquid phase main pipe tank. A liquefied hydrocarbon liquid phase collection valve 26 is installed on the liquefied hydrocarbon liquid phase collection pipe 27. An ESD valve 4 at the bottom of the liquid phase main pipe tank is installed on the vertical section of the liquid phase main pipe. A liquefied hydrocarbon liquid phase extraction valve 15 is installed on the horizontal section of the liquid phase main pipe. The dehydration pipe 1 includes a dehydration pipe inlet 16 and a dehydration pipe outlet 17. The dehydration pipe inlet 16 is connected to the liquefied hydrocarbon liquid phase main pipe 10. Directly below the horizontal section of the main phase pipe, the connection point is located between the liquefied hydrocarbon liquid phase extraction valve 15 and the liquid phase main pipe tank root ESD valve 4 and is close to the liquefied hydrocarbon liquid phase extraction valve 15. Preferably, the connection point is installed at the closest distance to the liquefied hydrocarbon liquid phase extraction valve 15. A dehydration pipe operating valve 5 is installed on the dehydration pipe 1 near the dehydration pipe inlet 16. The dehydration pipe outlet 17 is connected to the secondary dehydration tank 2. A sampler 23 is installed between the dehydration pipe inlet 16 and the dehydration pipe operating valve 5. A drain pipe 3 is led out from the center of the bottom of the secondary dehydration tank 2. A secondary dehydration tank drain pipe root valve 6 is installed on the drain pipe 3 near the secondary dehydration tank 2. The drain pipe 3 is led to the sewage system.A secondary dehydration tank gas phase outlet 18 is installed at the top of the secondary dehydration tank 2. A secondary dehydration tank vent pipe 13 is led from the secondary dehydration tank gas phase outlet 18 to the flare vent pipe 12. A secondary dehydration tank safety valve 14 is installed on the secondary dehydration tank vent pipe 13. A gas phase balance pipe 9 is led between the secondary dehydration tank safety valve 14 and the secondary dehydration tank gas phase outlet 18 and connected to the inlet pipe of the liquefied hydrocarbon tank safety valve. A gas phase balance pipe connecting valve 11 is installed on the gas phase balance pipe 9 near the secondary dehydration tank 2. An insertion-type intelligent electric float level gauge 19 is installed at the top of the secondary dehydration tank 2. A magnetic float level gauge 20 is installed in a position easily observed by the secondary dehydration tank 2.

[0023] The depth to which the insertion-type intelligent electric float level gauge 19 is inserted into the secondary dehydration tank 2 is measured by the distance from the bottom of the secondary dehydration tank, denoted by h1, and h1 is usually 50mm to 250mm.

[0024] The low liquid level value of the magnetic float level gauge 20 is 50mm to 150mm lower than the low alarm value of the intelligent electric float level gauge 19.

[0025] The dehydration pipe 1 enters the secondary dehydration tank step by step, that is, it slopes from the dehydration pipe inlet 16 to the dehydration pipe outlet 17. The vertical height of the dehydration pipe inlet 16 is higher than the vertical height of the dehydration pipe outlet 17, and the slope i is 0.002 to 0.05 to avoid the dehydration pipe from forming a dent. The dehydration pipe outlet 17 is connected to the secondary dehydration tank 2. The distance between the top of the dehydration pipe outlet 17 and the weld of the upper end cap is 100mm to 200mm, denoted by h2.

[0026] A spring valve 7 is installed between the sewage system and the drain pipe valve 6 of the secondary dewatering tank. The sewage entering the sewage system is first filtered before entering the sewage system. The filtration equipment is usually a funnel.

[0027] The horizontal section of the liquid phase main pipe 10 has a certain slope i, which is 0.002 to 0.05, and the slope direction is from the ESD valve 4 side of the liquid phase main pipe tank root to the liquefied hydrocarbon liquid phase extraction valve 15 side.

[0028] The liquid phase main tank root ESD valve 4 is an emergency shut-off valve with remote and local control functions, as well as failure prevention and fire prevention functions.

[0029] The secondary dehydration tank 2 is arranged below the liquefied hydrocarbon tank 8 and is located close to the dehydration pipe inlet 16 to minimize the length of the dehydration pipe.

[0030] The alarm value for the 0-level boundary of the intelligent electric float boundary gauge 19 on the secondary dehydration tank 2 is 250mm to 350mm, and the alarm value for the 100-level boundary is the center height of the dehydration pipe outlet 17.

[0031] A simple operating method for a liquefied hydrocarbon tank dehydration system according to the present invention is as follows:

[0032] The liquefied hydrocarbon liquid phase comes from process unit 25. The liquefied hydrocarbon liquid phase collection valve 26 is opened, and the liquefied hydrocarbon enters the liquefied hydrocarbon liquid phase main pipe 10 through the liquefied hydrocarbon liquid phase collection pipe 27 and then into the liquefied hydrocarbon tank 8. At this time, the liquefied hydrocarbon liquid phase extraction valve 15 and the dehydration pipe operating valve 5 are closed, and the ESD valve 4 at the bottom of the liquefied hydrocarbon tank liquid phase main pipe is normally open. When the liquefied hydrocarbon tank 8 stops receiving material, the liquefied hydrocarbon liquid phase collection valve 26 is closed. When the sampler 23, located before the dehydration pipe operating valve 5 and installed on the dehydration pipe 1, detects water, dehydration operation is required. During dehydration operation, the ESD valve 4 at the bottom of the liquefied hydrocarbon tank liquid phase main pipe is normally open, the liquefied hydrocarbon liquid phase extraction valve 15 and the liquefied hydrocarbon liquid phase collection valve 26 are closed, the dehydration pipe operating valve 5 is open, the gas phase balance pipeline connecting valve 11 is open, and the secondary dehydration tank drain pipe bottom valve 6 and the spring valve 7 are closed. Water in liquefied hydrocarbon tank 8 enters secondary dehydration tank 2 through liquefied hydrocarbon liquid phase main pipe 10 and dehydration pipe 1. The gas above the liquid level in secondary dehydration tank 2 increases in pressure as the liquid level rises. When the gas pressure above the liquid level in secondary dehydration tank 2 exceeds the gas phase pressure in liquefied hydrocarbon tank 8, the gas above the liquid level will enter liquefied hydrocarbon tank 8 along the gas phase balance pipe 9. When the intelligent electric float level gauge 19 reaches the 100 boundary level (the set upper limit boundary level for water and liquefied hydrocarbons), it will output a 4-20mA standard signal to the control room or issue an alarm signal locally, reminding personnel to manually drain the water, close the dehydration pipe operating valve 5, and then open the secondary dehydration tank. The drain pipe root valve 6 is opened, and then the spring valve 7 on the drain pipe 3 is manually pressed to perform secondary dehydration. As the liquid level in the secondary dehydration tank 2 decreases, the pressure of the gas above the liquid level in the secondary dehydration tank drops. When the gas phase pressure in the secondary dehydration tank 2 drops below the gas phase pressure in the liquefied hydrocarbon tank 8, the gas above the liquid level in the liquefied hydrocarbon tank 8 enters the secondary dehydration tank 2 along the gas phase balance pipe 9. When the intelligent electric float level gauge 19 drops to the 0 level (the lower limit level for water and liquefied hydrocarbons), an alarm is triggered locally. The operator releases the spring valve 7 to stop the secondary dehydration, then closes the drain pipe root valve 6 and the gas phase balance pipe connecting valve 11, and closes the dehydration pipe operating valve 5. If the sampler 23 detects water, the dehydration system repeats the above operation until the sampler 23 no longer detects water.

Claims

1. A liquefied hydrocarbon tank dehydration system, comprising a liquefied hydrocarbon tank, a dehydration pipe, a secondary dehydration tank, a drain pipe, a gas phase equilibrium pipe, a liquefied hydrocarbon liquid phase main pipe, a flare vent pipe, and a secondary dehydration tank vent pipe, characterized in that: The liquefied hydrocarbon tank is equipped with a safety valve inlet pipeline at the top, which is connected to the flare vent pipeline. A safety valve is installed on the safety valve inlet pipeline. The liquefied hydrocarbon liquid phase manifold includes a horizontal section and a vertical section. The top of the vertical section connects to the bottom of the liquefied hydrocarbon tank, and the bottom of the vertical section connects to one end of the horizontal section. The other end of the horizontal section connects to the pump inlet. An ESD valve is installed at the tank root of the vertical section, and a liquefied hydrocarbon liquid phase extraction valve is installed on the horizontal section. The dehydration pipe includes an inlet and an outlet. The inlet is connected directly below the horizontal section of the liquefied hydrocarbon liquid phase manifold, with the connection point located between the liquid phase extraction valve and the ESD valve at the tank root, and close to the liquid phase extraction valve. The dehydration pipe is equipped with a dehydration pipe operating valve, and the outlet of the dehydration pipe is connected to the secondary dehydration tank. A sampler is installed between the inlet of the dehydration pipe and the dehydration pipe operating valve. A drain pipe is led out from the bottom of the secondary dehydration tank, and a drain pipe root valve is installed on the drain pipe. The drain pipe is led to the sewage system. A gas phase outlet of the secondary dehydration tank is set at the top of the secondary dehydration tank. A vent pipe of the secondary dehydration tank is led from the gas phase outlet of the secondary dehydration tank to the flare vent pipe. A safety valve of the secondary dehydration tank is installed on the vent pipe of the secondary dehydration tank. A gas phase balance pipe is led between the safety valve of the secondary dehydration tank and the gas phase outlet of the secondary dehydration tank and connected to the inlet pipe of the safety valve of the liquefied hydrocarbon tank. A gas phase balance pipe connecting valve is installed on the gas phase balance pipe. An insertion-type intelligent electric float level gauge is installed at the top of the secondary dehydration tank. A magnetic float level gauge is installed in a position that is easy to observe in the secondary dehydration tank.

2. The liquefied hydrocarbon tank dehydration system according to claim 1, characterized in that: The insertion depth h1 of the insertion-type intelligent electric float interface gauge into the secondary dehydration tank is measured as the distance from the bottom of the secondary dehydration tank, and h1 is 50mm to 250mm.

3. The liquefied hydrocarbon tank dehydration system according to claim 1, characterized in that: The low liquid level value of the magnetic float level gauge is 50mm to 150mm lower than the low alarm value of the intelligent electric float level gauge.

4. The liquefied hydrocarbon tank dehydration system according to claim 1, characterized in that: The dehydration pipe gradually enters the secondary dehydration tank with a slope i of 0.002 to 0.

05.

5. A dehydration system for a liquefied hydrocarbon tank according to claim 1, characterized in that: The distance h2 between the top of the dehydration pipe outlet and the weld of the upper end cap is 100mm to 200mm.

6. A dehydration system for a liquefied hydrocarbon tank according to claim 1, characterized in that: The liquefied hydrocarbon tank dehydration system also includes a spring valve, which is installed between the sewage system and the tank root valve of the secondary dehydration tank drain pipe.

7. A dehydration system for a liquefied hydrocarbon tank according to claim 1, characterized in that: The horizontal section of the liquid phase main pipe has a certain slope, with a slope i of 0.002 to 0.05, and the slope direction is from the ESD valve side of the liquid phase main pipe tank root to the liquefied hydrocarbon liquid phase extraction valve side.

8. A liquefied hydrocarbon tank dehydration system according to claim 1, characterized in that: The secondary dehydration tank is located below the liquefied hydrocarbon tank and is positioned close to the inlet of the dehydration pipe. The 0-level alarm value of the intelligent electric float level gauge on the secondary dehydration tank is set to 250mm to 350mm, and the 100-level alarm value is the center height of the dehydration pipe outlet.

9. A dehydration system for a liquefied hydrocarbon tank according to claim 1, characterized in that: The wastewater entering the sewage system is first filtered before entering the system; the filtration device is a funnel.

10. A dehydration system for a liquefied hydrocarbon tank according to claim 1, characterized in that: The liquid phase main tank root ESD valve is an emergency shut-off valve with remote and local control functions, as well as failure prevention and fire prevention functions.

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