Discussion on leakage disposal measures in the hot

Discussion on leakage disposal measures in LPG tank area and loading and unloading area

LPG is a class a flammable and explosive dangerous chemical. Once a large amount of leakage occurs, it is easy to cause explosion and fire, causing heavy casualties and economic losses. On March 5, 1998, the bottom valve of a 4000 cubic meter LPG spherical tank of Xi'an gas company leaked due to serious wear and tear. Due to uncontrollable, two 400 cubic meter spherical tanks burst, killing 11 people and injuring 33 people. This is a typical case of heavy losses caused by unreasonable disposal measures of LPG leakage. This paper tries to make a superficial discussion on the disposal measures of LPG leakage from the perspective of technical measures that should be taken by petrochemical enterprises similar to the "Xi'an 98.3.5 explosion case"

1 risk of LPG leakage

LPG mainly contains low molecular hydrocarbons such as propane, butane, propylene, butene, etc., which has the property of gas-liquid two-phase. Under normal temperature and pressure, the liquid liquefied petroleum gas purified by PET (ethyl 2-benzoate) plastic sheet is very volatile. 1 liter of liquid liquefied petroleum gas can be converted into about 250 liters of gas after volatilization. Its gas density is greater than 1.5, heavier than air, and its explosion limit is 2% - 9% (vol). The liquefied petroleum gas leaks, and the gasified gas migrates to the depression along the ground. In the process of its migration, a large area of explosive gas mixture will be formed. Because the liquid light has the characteristics of latent heat of evaporation, when the liquefied petroleum gas leaks, it will vaporize rapidly and absorb a large amount of heat in the surrounding air (for example, the latent heat of evaporation of propane at 10 ℃ is 363.66j/g), so that the water in the air condenses into ice, causing the valve to freeze. However, it is difficult to shut down production because of the dynamic signal measured by the data laboratory machine. At the same time, LPG will generate high-level static electricity due to too fast flow rate when leaking. Practice has proved that the static voltage generated by LPG during high-speed injection is ≥ 9000v, especially when the gas contains other particulate substances, its static electricity is more dangerous. Therefore, once the leakage is difficult to control, the possibility of fire and explosion accidents is great

2 disposal measures for leakage in LPG tank area

leakage is the root cause of fire, and effectively stopping leakage is the key to prevent disaster accidents. In case of a large amount of leakage, it is strictly forbidden to panic. It is necessary to immediately delimit the warning area and strictly control the surrounding fire sources. The company adopts the mode of five business departments (laboratory machine manufacturing business department, measuring tools business department, industrial consumables business department, parts business department, system engineering business department), strictly prohibit irrelevant personnel from entering the leakage area, do a good job in personnel evacuation and alarm, organize personnel to rescue, and make fire prevention preparations such as pressure relief, venting, spraying, etc. Different methods should be adopted for leakage at different parts according to the actual situation

2. From this software, you can directly call the calculator 1. The large tanks in the tank farm and pipeline leakage

the large tanks in the tank farm have a large storage capacity, and the risk degree is the highest after leakage. According to the use frequency and installation position, the parts most prone to leakage are the inlet and outlet liquid-phase valves, blowdown valves, and gas-phase root valves, especially after the root valve leaks, it is difficult to deal with. In addition, considering time, corrosion and other factors, the problem of puncturing and leakage of pipelines or valves on pipelines may occur, which is discussed here

2.1.1 when the root valve punctures and leaks or the tank body punctures and leaks

in this case, we should first consider how to discharge the pressure in the tank in the shortest time, and be prepared for fire fighting. We can use the emergency standby tank or the nearest empty tank to pour the tank. According to practical experience, the accident tank will not be relieved when pouring, but the poured tank will be vented. When most of the liquid is poured, close the vent valve of the pouring tank and open the accident tank for venting. Why not consider emptying the accident tank at the beginning? Because a large amount of liquid is slowly vented through the gas phase, it takes the shortest time to pour a large amount of liquid into other tanks, which is faster than direct venting. For the tank pouring operation, it can be considered to pour the tank at the inlet and outlet. In the case that the tank cannot be poured at the inlet and outlet, technically, the pressurized gas phase pipeline of the top compressor can be used for liquid-phase tank pouring, and pump tank pouring is not considered. First, it takes a long time to pour the pump into the tank; second, cavitation of the pump may affect the speed of pouring the system; third, once the power is cut off on site, the pump cannot be used