The production, storage and transportation industry of hazardous chemicals is becoming more and more developed, and the transportation of hazardous chemicals is moving frequently. Various types of hazardous chemicals storage tanks and on-board liquefied hydrocarbon fuel tanks are more and more widely used. Due to the failure or collision of pipe fittings and valves, traffic and other accidents, the leakage of tank outlet, breather valve, injection port and other tank connecting pipeline accessories occur frequently and are impossible to prevent. If they cannot be cut off/closed effectively and quickly, they will cause a large number of leakage, resulting in fire or explosion accidents.
This research is mainly aimed at the parts prone to failure or be damaged, such as LNG, LPG, methane, ethane, chlorine, ammonia and other gas-phase, liquid-phase and gas-liquid two-phase hazardous chemicals storage tanks (bottles) / pipeline accessories (including pipelines and valves) of tank cars during storage, transportation and utilization. Based on the design idea of intrinsic safety, from the perspective of improving the safety performance of the tank, it is determined to install emergency self-sealing and blocking devices inside and outside the tank, and adopt the protection mode of multiple startup to realize the rapid emergency disposal of the leakage of tank valves and pipeline accessories, so as to improve the intrinsic safety of the tank to prevent leakage. At present, most of the relevant emergency plugging devices at home and abroad are external, and the leakage accidents of valves and pipeline accessories of hazardous chemicals storage tanks mostly adopt the method of external plugging, which has low operational reliability and safety. This achievement is proposed for the first time through the passive emergency self-plugging device set inside hazardous chemicals storage tanks, and there is no similar technology at home and abroad. At the same time, the developed external emergency self-sealing device provides an effective supplement as a strong backing. This research has developed a series of products of emergency self-sealing devices applicable to the leakage of pipeline accessories of gas-phase, liquid-phase and gas-liquid two-phase hazardous chemical storage tanks (bottles)/tank cars, compiled and formed the enterprise standard of emergency self-sealing devices for the leakage of pipeline accessories of hazardous chemical storage tanks, and determined the device installation methods for different specifications of hazardous chemical storage tanks (bottles)/tank cars, control technical methods and emergency disposal operation process. Five patents have been authorized for relevant achievements.
Gravity and pneumatic double protection emergency self-sealing device is built for storage tanks (bottles)/tank car
The main components of the device are gravity and pneumatic double protection one-way safety valves set at the internal medium channel port of hazardous chemical storage tank/tank car. Keep the channel normally open under the normal process state, which has no impact on the function and process flow of the external valve. In case of leakage of the pipeline accessories of the tank/tank car, the sealing surface of the valve core and the sealing surface of the valve seat can be pressed by rolling the tank at a certain angle, then the channel of the leakage accessories inside the tank can be automatically closed because of self-weight of the valve core. The double action of the gravity of the valve core and the pressure of the internal medium realizes the complete closure of the gravity one-way safety valve set in the hazardous chemical storage tank/tank car, completely blocks the medium from the source, and realizes the effective control of the medium in the hazardous chemical storage tank. For the large tank car which is difficult to rotate around the axis, nitrogen can be filled into the valve body by connecting with the high-pressure gas pipeline outside the tank, pushing the piston in the gas chamber, and pressing the valve core into the valve body to realize the emergency shutdown of the internal channel of the tank, so as to realize that the one-way safety valve set in the hazardous chemicals tank can be closed intact and completely block the medium from the inside of the tank, realize effective control of medium in hazardous chemicals storage tank.
Fig.1 Built-in gravity and pneumatic double protection emergency self-sealing device of storage tank/tank car
Chlorine cylinder valve Liquefied gas cylinder valve
Fig.2 Photo of Built-in gravity protection emergency self-sealing device for storage tank (bottle)
Multiple protection emergency self-sealing and blocking device is installed outside the storage tank (bottle)
The device is mainly composed of angle valve, angle valve hand wheel, packing and packing sleeve, angle valve plate, dumping closing steel ball and bracket, temperature sensing switch, etc., which are screwed with the storage tank (bottle). Open manually under normal use, turn the angle valve hand wheel counterclockwise, rotate the packing and drive the angle valve plate to move upward, so that the sealing ring provided in the groove at the lower end of the angle valve plate is separated from the angle valve closing convex bayonet in the upper end cavity of the angle valve body, the convex column returns to the air hole, and the gas is output from the air outlet of the valve body; When the ambient temperature rises abnormally to the setting temperature by the temperature sensing switch, the memory alloy spring of the temperature sensing switch extends, and the generated elastic force pushes the temperature closing steel ball downward, and finally contacts the temperature closing bayonet, blocks the temperature closing bayonet and cuts off the gas supply; After the tank (bottle) is dumped, the dumping closing steel ball located in the lower cavity of the angle valve body moves to the dumping closing bayonet under the action of gas and gravity in the tank, finally contacts the dumping closing bayonet and blocks the dumping closing bayonet; When closing in normal use, turn the angle valve hand wheel clockwise, the packing rotates and drives the angle valve plate to move downward, so that the sealing ring arranged in the groove at the lower end of the angle valve plate is pressed on the angle valve closing convex bayonet in the upper end cavity of the angle valve, and cut off the air source. The device can realize external emergency self-sealing disposal of various protection modes, such as dumping gravity start, abnormal start of ambient temperature rise and active start. Its structure and physical object are shown in Fig.3.
Fig.3 Structural section of external gravity protection emergency self-sealing device for storage tank (bottle)