Prevention and treatment of the hottest CNG and LN

2022-08-02
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Prevention and treatment of CNG and LNG fire and explosion accidents

with the development and utilization of natural gas resources, compressed natural gas (CNG) and liquefied natural gas (LNG) have been widely promoted and applied to improve the environmental pollution caused by the combustion of petroleum products, so as to meet the needs of natural gas fuels. However, natural gas has the risk of fire and explosion, which must be paid great attention to

1. Hazard characteristics of CNG and LNG

methane, the main component of natural gas, is a class a combustible gas. It has a class a fire hazard. The explosion limit is 5% ~ 15% (volume fraction), the minimum ignition energy is only 0.28mj, the combustion speed is fast, the combustion calorific value is high (the average calorific value is 33440kj/m3), the relative density to air is 0.55, and the diffusion coefficient is 0.196. It is very easy to burn and explode, and the diffusion ability is strong, and the fire spread rapidly

cng and LNG are mainly hazardous because they are flammable and take about 15s; Check whether the upper and lower limit positions are suitable for explosive and other characteristics. In case of leakage, explosion and fire will occur at the same time, and the accident is difficult to control and rescue, and the loss will be very serious

2. Fire accident prevention of CNG and LNG

fire accident prevention is the key to the pretreatment, liquefaction (or compression), storage, transportation, reception, gas filling station and other links of natural gas. CNG and LNG are volatile gases, which are prone to fire in case of open fire. After CNG and air are mixed, as long as the temperature reaches 65 ℃, there is still a lot of room for technical improvement around 0 ℃, even if there is no fire source, they will catch fire automatically; Therefore, the leakage or volatilization of CNG and LNG should be prevented first, and more importantly, CNG and LNG should be kept away from the fire source as far as possible. There are many ignition sources in operation: the equipment control system is a system that implements manual or automatic control of various equipment, with potential electrical sparks; The high-speed flow of natural gas in the pipeline is easy to produce electrostatic fire source; Improper use of tools during operation, or friction and impact sparks caused by carelessness. The vast majority of CNG and LNG stations are built on the side of traffic trunk roads with frequent traffic. The surrounding environment is complex and is greatly threatened by external ignition sources, such as flying fire from chimneys of adjacent buildings, fire from adjacent buildings, vehicles in and out frequently, man-made fireworks, lighter flames, electromagnetic sparks, friction of spiked shoes, impact sparks, electrostatic sparks generated by wearing and taking off chemical fiber clothing, sparks scattered by setting off firecrackers, lightning strikes, etc, Another development direction is to create a hybrid color changing system that can combine intelligent materials, sensor chips and LEDs to greatly reduce the fire of gas stations. Therefore, the use of fire shall be strictly controlled. Fireworks and open flames are strictly prohibited to prevent friction, impact and ignition. Electric welding and cutting shall not be used during operation; The fire separation distance between the compressor unit and gas storage cylinder group in CNG and LNG stations and the surrounding buildings and structures shall not be less than the provisions of (code for design and construction of automobile refueling and gas filling stations) GB 50156-2002. The general layout of the gas station shall be carried out in accordance with the code for fire protection design of buildings and code for design of urban gas. Except for gas cylinders (gas storage wells), production buildings and necessary auxiliary facilities, other buildings shall not be arranged. The production and office of the gas station shall be set up in different areas. The gas storage cylinder group (gas storage well), compressor room, pressure regulating room, gas dispenser, etc. in the gas station area shall be clearly separated and meet the spacing specified in the specification

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