Hazard Analysis and Storage Hazards in Low Temperature Storage Tank Areas

（1） Hazard analysis of LNG storage tank area (1) LNG is stored in low-temperature storage tanks and is in a boiling state. At the end of some pipelines and liquefaction sections in the LNG storage tank area, it is close to boiling state. The introduction of external heat can cause gasification and high pressure, resulting in the opening of the safety valve or causing significant damage. Rolling: Due to the different composition and density of LNG in the storage tank, stratification occurs, and mass and heat transfer occur between the two layers, ultimately completing mixing while evaporating on the surface of the liquid layer. This evaporation process absorbs heat from the upper liquid, causing the lower liquid to become overheated. When the densities of two liquids are close to equal, they will suddenly mix at a suitable speed and produce a large amount of gas in a short period of time, causing the pressure inside the storage tank to rise sharply and even opening the safety valve. To avoid this danger, special measures should be taken: ① Light LNG is fed from the bottom of the tank, or heavy LNG is fed from the top of the tank, or a combination of both; ② Install an automatic density meter in the slot to detect layers of different densities; ③ Use a pump in the tank to circulate the liquid from bottom to top; ④ Maintain the nitrogen content of LNG below 1% and closely monitor the gasification rate. (2) Due to LNG being a cryogenic liquid with a temperature of -162 ℃, direct contact between the skin and the surface of low-temperature objects can cause serious injuries in LNG gas cylinder storage tanks. When in direct contact, moisture on the surface of the skin condenses and adheres to the surface of low-temperature objects. The skin and tissues below the skin freeze, making it easy to tear and leave wounds. After bonding, the skin can be thawed by heating and then peeled off. At this point, if the skin is forcefully torn off the low-temperature surface, it will tear this part of the skin apart. Low temperature liquids have lower viscosity and can penetrate textiles or other porous fabrics faster than other liquids such as water. When handling anything that comes into contact with or has come into contact with low-temperature liquids or vapors, if non absorbent gloves (made of PVC or leather) are not worn and the gloves are not loose, the gloves are not easy to remove when liquid splashes onto or seeps into the gloves. If there is a possibility of intense spraying or splashing, do not use a face mask or goggles to protect your eyes. Low temperature accidents may occur. (3) Due to low-temperature operation, the leakage of LNG can cause significant shrinkage of metal components. Leakage and boiling evaporation can occur at any part of the pipeline system, especially at welds, valves, flanges, fittings, seals, and cracks. If these vapors are not sealed in time, they will gradually rise and spread far away, making it easy to encounter potential sources of fire, explosions, low temperatures, and other accidents. (4) Low temperature anesthesia does not have sufficient protective measures. After staying below 10 ℃ for a long time, there is a risk of low temperature anesthesia. As body temperature decreases, physiological function and intellectual activity decline, heart failure, and further decline can lead to death. (5) Breathing LNG low-temperature vapor through suffocation is harmful to health. In the short term, it can lead to difficulty breathing, and over time, it can have serious consequences. Although LNG vapor is not toxic, its low oxygen content can easily cause suffocation. If pure LNG vapor is inhaled and not released at a suitable speed, one will quickly lose consciousness and die after a few minutes. When the oxygen content in the air gradually decreases, the operators have no feeling or warning. By the time you realize it, it will be too late. There are four types of suffocation:. A、 Scenario 1: Oxygen content of 14% to 21% (volume content, the same below), accelerated breathing and pulse, accompanied by muscle twitching. B、 Scenario 2: Oxygen content of 10% to 14%, accompanied by hallucinations, fatigue, and delayed response to pain. C、 Scenario 3: Oxygen content of 6% to 10%, accompanied by nausea, vomiting, fainting, and brain damage. D、 Scenario 4: Oxygen content below 6%, accompanied by spasms, respiratory arrest, and death. Usually, an oxygen content of 10% is the lower limit for the human body to prevent damage. Correspondingly, normal air contains 52.4% methane, with an oxygen content of 10%. Therefore, we advise everyone not to enter LNG vapor. （2） The hidden dangers of LNG storage and transportation: 1. The transportation of LNG tank trucks carries risks. For the transportation of liquefied natural growth gas storage tanks, the management is relatively extensive and lacks sufficient awareness, leading to many accidents. And some vehicles, whose performance has not been protected due to prolonged use, are still used as transportation tools, and these types of vehicles should be phased out. The lack of vacuum insulation performance in tank trucks is also a serious problem, as it generates a large amount of gas emissions during transportation, which is not conducive to environmental protection. Many vehicles have insufficient protective devices, posing significant risks. Some production enterprises also seek to gain more benefits by driving multiple vehicles in close proximity, without paying attention to distance, which brings certain risks to the transportation process. 2. The problem of LNG leakage is highly likely to occur during transportation due to the inability to meet low temperature requirements and insufficient equipment sealing. When natural growth gas leaks, it can cause economic losses and also lead to the occurrence of explosion accidents. Once LNG stored at 120 ℃ leaks, people may experience suffocation and other serious situations when exposed to such low temperatures. 3. The LNG transportation loss gas G storage phase pipe is directly connected to the engine, resulting in LNG loss through the direct utilization of vaporized LNG. Under normal circumstances, the usage is generally small, and when adjusting the air pressure at the terminal, the carrier can obtain certain benefits through this method. If encountering illegal merchants, the loss of natural growth will be significant. The increasing use of liquefied natural growth gas (LNG) has led to a rapid development of the LNG industry, and with the advancement of technology, LNG storage and transportation have also been protected. However, the flammability, low temperature, and fast transformation of LNG have also brought many difficulties to the storage and transportation of LNG. At present, there are three main modes of LNG transportation: tanker transportation, ship transportation, and pipeline transportation. There are hidden dangers such as leakage and gas loss in LNG storage and transportation. Choosing the materials of LNG storage and transportation equipment, taking sufficient protective measures, and standardizing the management standards of the LNG storage and transportation industry are measures to protect LNG storage and transportation.