Semi-fixed carbon dioxide system of oil storage tank and protection method

Abstract

The invention relates to the technical field of petroleum storage tanks, in particular to a petroleum storage tank semi-fixed carbon dioxide system and a protection method. The petroleum storage tank semi-fixed carbon dioxide system comprises a movable critical state carbon dioxide fire extinguishing device and an external floating roof petroleum storage tank; the movable critical state carbon dioxide fire extinguishing device is connected with one end of a metal hose, the other end of the metal hose is connected with a control valve box, the control valve box is connected with one end of a ground pipeline, the other end of the ground pipeline is connected with the metal hose, and one end of the metal hose is connected with a storage tank vertical pipe. The top of the storage tank vertical pipe is connected with an escalator pipeline through a metal hose, the bottom of the escalator pipeline is connected with a drag chain, and the drag chain is connected with a drag chain guide groove assembly. All equipment and instruments related to the carbon dioxide fire extinguishing system are explosion-proof equipment and are installed outside the oil storage tank, no power circuit is arranged in the oil storage tank, secondary disasters caused by circuit faults are avoided, and intrinsic safety is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum storage tanks, in particular to a semi-fixed carbon dioxide system for petroleum storage tanks and a protection method thereof. Background Art

[0002] As the main facilities for storing crude oil on the ground, large oil storage tanks have the advantages of low oil loss, environmental protection, and space saving. Oil and its liquid products are flammable and explosive dangerous goods. The large-scale oil storage tanks will inevitably bring huge challenges to the fire safety of oil storage and transportation. Oil storage tanks mostly use external floating roof structures. Most of the fires in external floating roof tanks come from the primary and secondary sealing rings of the external floating roof structure. Lightning strikes are the main cause of fires in sealing rings. In this type of fire, there will first be a "flash explosion", which will cause damage to some secondary seals and foam weir plates, forming a partially open three-sided restricted combustion space; then the sealing ring will completely catch fire; and finally the tank will collapse.

[0003] External floating roof tanks may also have the floating plate overturned or sunk due to structural and construction quality reasons. Fire, explosion and overturning and sinking accidents of large floating roof oil storage tanks will cause heavy casualties and property losses, and will also cause large-scale environmental pollution. According to the research on fire protection technology and products of large oil storage tanks at home and abroad, the main fire protection means of large oil storage tanks are foam fire extinguishing systems, mobile fire monitors, fire water cooling systems and fire rescue.

[0004] Traditional foam fire extinguishing systems have the following disadvantages:

[0005] 1) The traditional sealing ring foam fire extinguishing system takes a long time from system startup to covering the entire liquid surface. Once the fire is put out at the early stage, it is difficult to deal with it;

[0006] 2) Foam fire extinguishing agents cause great pollution to crude oil. Once mis-spraying or leakage occurs, the economic losses will be serious;

[0007] 3) Fire develops rapidly and is often accompanied by explosions, which may damage secondary seals, foam weirs, foam generators or foam fire extinguishing pipe networks, causing partial or complete failure of the fire extinguishing system.

[0008] 4) Spreading the foam fire extinguishing agent over a large area on the floating platform will increase the floating roof load. For an already tilted floating platform, it will accelerate the tilt and even cause the top to sink.

[0009] In view of the above problems, we propose a semi-fixed carbon dioxide system and protection method for oil storage tanks. Summary of the invention

[0010] The object of the present invention is to provide a semi-fixed carbon dioxide system for petroleum storage tanks and a protection method thereof, so as to solve the problems raised in the above-mentioned background technology.

[0011] To achieve the above object, the present invention provides the following technical solutions:

[0012] A semi-fixed carbon dioxide system for a petroleum storage tank, comprising:

[0013] Mobile critical carbon dioxide fire extinguishing equipment and external floating roof oil storage tanks;

[0014] A mobile critical carbon dioxide fire extinguishing device is connected to one end of a metal hose, the other end of the metal hose is connected to a control valve box, the control valve box is connected to one end of a ground pipeline, the other end of the ground pipeline is connected to a metal hose, one end of the metal hose is connected to a storage tank riser, the top of the storage tank riser is connected to an escalator pipeline through a metal hose, the bottom of the escalator pipeline is connected to a drag chain, the drag chain is installed on a drag chain guide groove assembly, and is connected to a floating roof pipeline inside an external floating roof oil storage tank, and a plurality of carbon dioxide special nozzles are provided at the end of the floating roof pipeline.

[0015] Preferably, the mobile critical carbon dioxide fire extinguishing device is connected to the control valve box through a metal hose;

[0016] The control valve box is used to control the supply of liquid carbon dioxide to the mobile critical carbon dioxide fire extinguishing device.

[0017] Preferably, the control valve box is connected to a ground pipeline;

[0018] The ground pipeline is used for the ground liquid carbon dioxide transportation pipeline.

[0019] Preferably, the ground pipeline is connected to the storage tank riser through a metal hose;

[0020] The storage tank riser is used for the liquid carbon dioxide delivery pipeline.

[0021] Preferably, the tank riser is connected to the escalator pipeline through a metal hose;

[0022] The escalator pipeline is used as a liquid carbon dioxide delivery pipeline at the escalator.

[0023] Preferably, the escalator pipeline is connected to the top of the external floating roof oil storage tank through a drag chain and a drag chain guide groove assembly.

[0024] Preferably, the floating roof pipeline is a pipeline for conveying liquid carbon dioxide to each carbon dioxide dedicated nozzle.

[0025] A protection method for a semi-fixed carbon dioxide system of a petroleum storage tank comprises the following steps:

[0026] The mobile critical state carbon dioxide fire extinguishing device inerts the space formed between the floating plate and the tank wall of the external floating roof oil storage tank by filling carbon dioxide liquid into the space. The carbon dioxide liquid absorbs heat and vaporizes to quickly fill the protective space of the external floating roof oil storage tank and spread to the entire bottom of the tank. The columnar inerting protection space formed between the floating plate and the tank wall isolates the air, turning the original fire hazard space into an inert protection space.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] In case of an emergency, when the floating plate rolls over or sinks, the mobile critical carbon dioxide equipment will fill the columnar space formed between the floating plate and the tank wall through the fixed carbon dioxide pipeline network installed on the oil storage tank, and the carbon dioxide liquid will spread to the surface of the floating plate of the external floating roof tank to form an inert layer, so as to control the oxygen content and the flammable mixed gas content in the space within the specified range, and prevent the floating plate from rolling over or sinking due to collision, friction or lightning strikes and other factors to generate sparks and cause oil tank fires, so that the original fire hazard space is transformed into an inert protection space and can also prevent the volatilization of light oil products from causing environmental pollution.

[0029] The present invention utilizes carbon dioxide as an inert gas. Due to its strong fluidity and being heavier than air, an inert layer is formed on the floating plate or the oil liquid surface and the tank wall of an external floating roof type oil storage tank, thereby protecting the space and isolating the oil, flammable volatiles or the floating plate in the space from the air, preventing them from burning or exploding, and greatly reducing the possibility of fire in the space.

[0030] The method adopted by the present invention can spray liquid carbon dioxide to extinguish fire in the shortest time, and the response time is short; and the mobile critical carbon dioxide fire extinguishing device has a strong application advantage for large space and long distance (about 500m) protection objects. Carbon dioxide has much higher fluidity than foam and can also cool the storage tank, so the fire extinguishing efficiency of carbon dioxide is much higher than that of foam. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the structure of the present invention;

[0032] Figure 2 It is a schematic diagram of the cross-sectional structure of the sealing ring of the present invention.

[0033] In the figure:

[0034] 1. Mobile critical carbon dioxide fire extinguishing device; 2. Control valve box; 3. Ground pipeline; 4. Storage tank riser; 5. Escalator pipeline; 6. Drag chain; 7. Drag chain guide groove assembly; 8. Floating roof pipeline; 9. Carbon dioxide special nozzle; 10. Metal hose; 11. External floating roof oil storage tank. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Embodiment 1:

[0037] See also Figure 1 , Figure 2 To achieve the above purpose, the present invention provides the following technical solutions:

[0038] A semi-fixed carbon dioxide system for a petroleum storage tank, comprising:

[0039] A mobile critical carbon dioxide fire extinguishing device 1 and an external floating roof oil storage tank 11;

[0040] The mobile critical carbon dioxide fire extinguishing device 1 is connected to one end of a metal hose 10, and the other end of the metal hose 10 is connected to a control valve box 2. The mobile critical carbon dioxide fire extinguishing device 1 is connected to the control valve box 2 through the metal hose 10. The control valve box 2 is used to control the supply of liquid carbon dioxide of the mobile critical carbon dioxide fire extinguishing device 1. The control valve box 2 is connected to one end of a ground pipeline 3. The control valve box 2 is connected to the ground pipeline 3. The ground pipeline 3 is used for the ground liquid carbon dioxide delivery pipeline. The other end of the ground pipeline 3 is connected to the metal hose 10. One end of the metal hose 10 is connected to a storage tank riser 4. The ground pipeline 3 is connected to the storage tank riser 4 through the metal hose 10. Pipe 4 is used for liquid carbon dioxide delivery pipeline, the top of storage tank riser 4 is connected with ladder pipe 5 through metal hose 10, storage tank riser 4 is connected with ladder pipe 5 through metal hose 10, ladder pipe 5 is used for liquid carbon dioxide delivery pipeline at ladder, the bottom of ladder pipe 5 is connected with drag chain 6, drag chain 6 is connected with drag chain guide groove assembly 7, ladder pipe 5 is connected to the top of external floating roof oil storage tank 11 through drag chain 6 and drag chain guide groove assembly 7, floating roof pipe 8 is installed at the bottom of external floating roof oil storage tank 11, a plurality of carbon dioxide special nozzles 9 are provided at the end of floating roof pipe 8, floating roof pipe 8 is used for pipeline for delivering liquid carbon dioxide to each carbon dioxide special nozzle 9.

[0041] Embodiment 2:

[0042] A protection method for a semi-fixed carbon dioxide system of a petroleum storage tank comprises the following steps:

[0043] The mobile critical state carbon dioxide fire extinguishing device 1 is inerted by filling carbon dioxide liquid into the space formed between the floating plate and the tank wall of the external floating roof oil storage tank 11. The carbon dioxide liquid can quickly fill the protective space of the external floating roof oil storage tank after absorbing heat and vaporizing, and spread to the entire bottom of the storage tank. The columnar inerting protection space formed between the floating plate and the tank wall isolates the air, so that the original fire hazard space is converted into an inert protection space.

[0044] Embodiment 3:

[0045] Take a 100,000 cubic meter external floating roof oil storage tank as an example (100,000 m 3 The circumference of the oil tank is 251.2 meters):

[0046] This system protects the seal ring of a large external floating roof oil storage tank. For the reliability of the system, the protection space is mainly the seal ring cavity area. The detailed dimensions of the seal ring section are shown below. Figure 2 :

[0047] The amount of fire extinguishing agent should take into account the amount of agent used for primary and secondary sealed gap fire extinguishing.

[0048] Refer to the "Design Specifications for Carbon Dioxide Fire Extinguishing Systems" for primary and secondary sealed gap fire extinguishing

[0049] GB50193-93 (2010 edition) explains that the area method is used for calculation, and the fire extinguishing intensity is based on the Japanese standard of 13kg / m2, which is calculated as follows:

[0050] Fire extinguishing agent dosage for primary and secondary sealing gaps = area × fire extinguishing intensity = 0.25 × 252 × 13 = 819 kg

[0051] According to the specifications, the carbon dioxide spraying time of the total flooding fire extinguishing system should not be greater than 1 minute.

[0052] Therefore, the flow rate in the main pipe is: 819kg÷1min=819kg / min

[0053] The flow rate of each nozzle is: 819kg / min÷8=102.4kg / min

[0054] Therefore, it is calculated that the design consumption of carbon dioxide for full flooding fire extinguishing in the primary and secondary sealed gaps of this project is 819kg, and the nozzle flow rate is 102.4kg / min.

[0055] The ground and riser carbon dioxide pipelines use one DN65 galvanized steel pipe, with the longest length of about 200m. The escalator and part of the tank top carbon dioxide pipelines use two DN40 galvanized steel pipes, and the floating roof carbon dioxide branch pipes use eight DN20 galvanized steel pipes.

[0056] According to the test, during the critical carbon dioxide spraying process, the medium in the pipeline is liquid carbon dioxide. According to:

[0057]

[0058] Where, l is the length of the pipeline in m,

[0059] Q w ——Liquid flow rate m 3 / h

[0060] d——Inner diameter of the pipe m

[0061] v——Liquid flow rate m / s

[0062] Δ p ——Pressure loss Pa

[0063] μ——friction coefficient

[0064] SG——Liquid Specific Gravity

[0065] The main pipeline calculation results are as follows:

[0066]

[0067]

[0068] After calculation, the pressure drop and flow rate meet the relevant requirements.

[0069] When the floating plate of an external floating roof tank sinks or overturns:

[0070] Consider that gaseous carbon dioxide forms an inert gas space of 5m high between the floating plate and the tank wall of the external floating roof tank. Then:

[0071] The carbon dioxide spraying time is: 4 minutes.

[0072] Protective space volume = floating roof area × inert gas coverage height = 5024m 2 ×5m=25120m 3 .

[0073] The liquid-to-gas conversion ratio of one cubic meter of liquid carbon dioxide is 560.

[0074] The volume of liquid carbon dioxide required for inerting space is: 25120m 3 ÷560=44.9m 3

[0075] Simply connect the required amount of carbon dioxide to the tank truck.

[0076] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A semi-fixed carbon dioxide system for oil storage tanks, characterized in that: include: A mobile critical carbon dioxide fire extinguishing device (1) and an external floating roof petroleum storage tank (11); A mobile critical carbon dioxide fire extinguishing device (1) is connected to one end of a metal hose (10), the other end of the metal hose (10) is connected to a control valve box (2), the control valve box (2) is connected to one end of a ground pipeline (3), the other end of the ground pipeline (3) is connected to a metal hose (10), one end of the metal hose (10) is connected to a storage tank riser (4), the top of the storage tank riser (4) is connected to an escalator pipeline (5) through the metal hose (10), the bottom of the escalator pipeline (5) is connected to a drag chain (6), the drag chain (6) is installed on a drag chain guide groove assembly (7), and is connected to a floating roof pipeline (8) inside an external floating roof oil storage tank (11), and a plurality of carbon dioxide special nozzles (9) are provided at the end of the floating roof pipeline (8).

2. A semi-fixed carbon dioxide system for oil storage tanks according to claim 1, characterized in that: The mobile critical carbon dioxide fire extinguishing device (1) is connected to the control valve box (2) via a metal hose (10); The control valve box (2) is used to control the supply of liquid carbon dioxide to the mobile critical carbon dioxide fire extinguishing device (1).

3. The semi-fixed carbon dioxide system for petroleum storage tanks according to claim 1, characterized in that: The control valve box (2) is in communication with a ground pipeline (3); The ground pipeline (3) is used as a ground liquid carbon dioxide transportation pipeline.

4. The semi-fixed carbon dioxide system for petroleum storage tanks according to claim 1, characterized in that: The ground pipeline (3) is connected to the storage tank riser (4) through a metal hose (10); The storage tank riser (4) is used for the liquid carbon dioxide delivery pipeline.

5. The semi-fixed carbon dioxide system for petroleum storage tanks according to claim 1, characterized in that: The storage tank riser (4) is connected to the escalator pipeline (5) through a metal hose (10); The escalator pipeline (5) is used as a liquid carbon dioxide delivery pipeline at the escalator.

6. The semi-fixed carbon dioxide system for petroleum storage tanks according to claim 1, characterized in that: The escalator pipeline (5) is connected to the top of the external floating roof oil storage tank (11) through a drag chain (6) and a drag chain guide groove assembly (7).

7. The semi-fixed carbon dioxide system for petroleum storage tanks according to claim 1, characterized in that: The floating roof pipeline (8) is a pipeline used to transport liquid carbon dioxide to each carbon dioxide-dedicated nozzle (9).

8. A protection method for a semi-fixed carbon dioxide system of a petroleum storage tank according to any one of claims 1 to 7, characterized in that: The following steps are involved: The mobile critical state carbon dioxide fire extinguishing device (1) is inerted by filling carbon dioxide liquid into the space formed between the floating plate and the tank wall of the external floating roof oil storage tank (11). The carbon dioxide liquid can quickly fill the protective space of the external floating roof oil storage tank after absorbing heat and evaporating, and spread to the entire bottom of the storage tank. The columnar inerting protection space formed between the floating plate and the tank wall isolates the air, so that the original fire hazard space is converted into an inert protection space.

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