CN-121990280-A - Device and method for reducing concentration of combustible gas in twice sealed space of floating roof tank

Abstract

The invention discloses a device for reducing the concentration of combustible gas in a twice sealed space of a floating roof tank, which comprises an outer floating roof oil storage tank, wherein an air inlet pipe and an air suction pipeline are respectively communicated with the twice sealed space in the outer floating roof oil storage tank, a one-way valve is arranged at the other port of the air inlet pipe, the other end of the air suction pipeline is respectively communicated with an air suction pump and a pretreatment device, the pretreatment device is connected with a gas detection instrument through the air suction pipeline, the gas detection instrument is electrically connected with a control system, the gas detection instrument is connected with a gas recovery treatment device through the air suction pipeline, the air suction pump is connected with the gas recovery treatment device through the air suction pipeline, and the air suction pump is electrically connected with the control system. The invention also discloses a method for reducing the concentration of the combustible gas. According to the device and the method for reducing the concentration of the combustible gas in the twice sealed space of the floating roof tank, disclosed by the invention, the gas in the sealed space of the external floating roof tank is controlled within a safe range through detecting and discharging the concentration of the gas in the external floating roof tank, so that the sealing ring fire caused by lightning stroke and static electricity is avoided.

Inventors

• TAN KAI
• HU CHUNLIN
• ZHANG MAI
• YAN QIANG
• ZHAO PENG
• LI YONGSHENG
• DONG YANGUO
• ZHANG YUQIANG
• YAN RUIHANG
• YANG JIANDONG
• SHI BAINI

Assignees

• 长庆工程设计有限公司
• 中国石油天然气集团有限公司

Dates

Publication Date

20260508

Application Date

20241101

Claims (7)

1. 1. The device for reducing the concentration of the combustible gas in the twice sealed space of the floating roof tank is characterized by comprising an outer floating roof oil storage tank (1), a primary seal (12) and a secondary seal (8) are arranged in the edge of a floating disc of the outer floating roof oil storage tank (1), the secondary seals (8) are respectively communicated with an air inlet pipe (9) and an air exhaust pipe (11), a one-way valve (10) is arranged at the other port of the air inlet pipe (9), a pretreatment device (2) and an air exhaust pump (6) are respectively communicated with the other end of the air exhaust pipe (11), the pretreatment device (2) is connected with a gas detection instrument (3) through the air exhaust pipe (11), the gas detection instrument (3) is electrically connected with a control system, the gas detection instrument (3) is connected with a gas recovery treatment device (7) through the air exhaust pipe (11), and the air exhaust pump (6) is electrically connected with the control system.
2. 2. The device for reducing the concentration of combustible gas in the twice sealed space of the floating roof tank according to claim 1, wherein the control system comprises a PLC field control cabinet (4) and a remote automatic control device (5), the PLC field control cabinet (4) is electrically connected with the remote automatic control device (5), and the gas detection instrument (3) is electrically connected with the PLC field control cabinet (4).
3. 3. The device for reducing the concentration of the combustible gas in the twice sealed space of the floating roof tank according to claim 2, wherein the air pump (6) is electrically connected with the PLC field control cabinet (4) and the remote automatic control device (5) respectively.
4. 4. The method for reducing the concentration of the combustible gas is characterized by comprising the following specific steps of: Step 1, detecting the gas concentration in an external floating roof oil storage tank (1), and transmitting a detection result to a control system; And 2, when the detected gas concentration value exceeds the set concentration value, the control system controls the action of the air pump (6), and when the air pressure difference reaches the limit value, the one-way valve (10) is opened, so that the gas concentration in the sealed space is controlled within the set concentration value range.
5. 5. The method for reducing the concentration of the combustible gas according to claim 4, wherein the step 1 is specifically that the gas in the external floating roof oil storage tank (1) is transported to a gas detection instrument (3) through the air pump (6), the concentration of the gas is detected through the gas detection instrument (3), the detection result is transmitted to the PLC field control cabinet (4), and the PLC field control cabinet (4) transmits the detection result to a remote automatic control device (5).
6. 6. The method of reducing the concentration of the combustible gas according to claim 4, wherein the step 2 is specifically that when the remote automatic control device (5) receives the detection result exceeding the set concentration value, an instruction is sent to control the operation speed of the air pump (6) to be increased, part of the gas is pumped out, the air pressure in the sealing ring is reduced to open the one-way valve (10), the outside air is pumped into the sealing space to replace the original gas until the concentration value of the gas is lower than the set concentration value, the operation speed of the air pump (6) is reduced to enable the air pressure to be balanced, and finally the one-way valve (10) is closed.
7. 7. The method for reducing the concentration of combustible gas according to claim 6 further comprising step 3 of discharging the gas exceeding the set concentration value through the gas recovery processing device (7) and discharging.

Description

Device and method for reducing concentration of combustible gas in twice sealed space of floating roof tank Technical Field The invention belongs to the technical field of safety and environmental protection of an external floating roof oil tank, and particularly relates to a device for reducing the concentration of combustible gas in a twice sealed space of a floating roof tank and a method for reducing the concentration of the combustible gas. Background The storage tank is used as a common storage device, is widely applied in the petroleum and chemical industries, and the vault tank and the floating roof tank are the most widely applied crude oil storage tanks. Wherein, floating roof tank seals storage medium, reduces the medium temperature through installing the floating disc in the jar body, reaches the purpose of energy saving. In the operation process of the conventional floating roof storage tank, the sealing ring fire disaster case caused by lightning stroke or static electricity exists in the storage tank, the problem that the oil is hung on the floating roof tank is difficult to avoid, the inner wall of the storage tank is tightly clung to the twice sealing of the storage tank, and the problem that flammable gas exists in the twice sealing space for a long time is difficult to solve. Fire of an external floating roof oil tank mostly occurs at a sealing part of a storage tank, and sealing ring ignition caused by lightning stroke or static electricity is usually started from gas flash explosion in a primary sealing space and a secondary sealing space. In the prior art, in order to reduce the loss caused by oil tank fire, a fire-fighting spraying and foam extinguishing device and a fire detection device are usually arranged on a floating roof storage tank, and protection is realized through the interlocking control of a system in a station. The fire control sprays and is used for the cooling of storage tank outer wall, prevents that the conflagration from spreading and influencing other storage tanks, and foam fire extinguishing system fills fire control foam to between storage tank inner wall and the foam weir plate, isolated sealed space and air reach the effect of putting out a fire. The large-scale petroleum station is also provided with fire-fighting measures such as fire trucks, and personnel participate in the fire control more flexibly, so that the fire control system has a better effect on the initial control of the fire. However, these fire protection measures of the storage tank are all to passively extinguish the fire after the storage tank is in fire, the detection and the action of the system have certain hysteresis, and the fire protection measures such as foam, water and the like can be contacted with the fire part only by waiting for a certain time, so that the fire protection effect is affected. Under extreme weather conditions such as strong wind, fire fighting foam is easily blown off in the falling process and falls outside a designated area, so that the fire fighting mode is disabled. Fire-fighting vehicles have great risks of personal injury and the like, and the application range is smaller. In order to reduce the risk of fire and avoid passive extinguishment afterwards as much as possible, the invention patent of an external floating roof type active safety protection system and a protection method for a petroleum storage tank, which are applied by September of two zero to one zero, has the publication number of CN101985328A, and the volatile gas is diluted by injecting inert gas into a secondary sealed space of the storage tank, so that the sealed space is kept in a micro-positive pressure state, and the volatile gas is directly discharged into the atmosphere, thereby causing environmental pollution. Meanwhile, the inert gas is diffused to the surface of the floating disc along with the gas, so that the risk of suffocation of operators exists, and a common oil storage station is not provided with the inert gas, and a set of inert gas preparation and storage device is required to be independently arranged for the system, so that the operation cost of the storage is further increased. External floating roof crude oil storage tanks are commonly found in large petroleum reservoirs for storing crude oil, and standard specifications require that such tanks must be equipped with spraying and foam fire protection facilities. Meanwhile, SY/T5921 ' operation maintenance repair Specification for vertical cylindrical steel welding oil tanks ' prescribes that the concentration of combustible gas between a secondary seal or a rain shield and a primary seal is checked in summer and does not exceed 25% of the lower explosion limit ', but because a floating roof tank of an oil storage warehouse is always in a floating disc static state, the secondary seal contacts with a tank wall, crude oil attached to the tank wall volatilizes into a sealed space, and the concentration of the gas is easy