Fire risk analysis and fire prevention of sewer sy

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Fire risk analysis and fire prevention of sewage system in chemical enterprises

with the construction of high-speed railway in China, especially the construction of "four vertical and four horizontal", the main problem in production is that the materials used consume a lot of industrial water, and the amount of sewage that needs to be discharged or sent to sewage purification treatment is very large. The sewer system of chemical enterprises often accumulates combustible gases or vapors, or combustible and explosive dirt. The sewer system is all over the enterprise area, and a fire will affect the whole enterprise. Therefore, the sewer system is one of the key objects that can not be ignored in the fire prevention work of chemical enterprises

1 fire and explosion risk analysis of sewer system

China's plastic machinery enterprise market will be more open. 1.1 it is easy to form an explosive mixture of flammable vapor (or gas) and air

the production wastewater or other drainage of chemical enterprises inevitably contains flammable liquids or soluble flammable gases. Under certain conditions, these flammable liquids or gases are easy to form explosive mixtures with air in sewer systems and purification facilities due to gasification

if the airtightness of the production equipment system is damaged or the operation regulations are violated, resulting in overflow, the leaked flammable and explosive liquid or gas is often easy to mix into the sewage and enter the sewer system. Due to the violation of production process regulations, a large amount of hydrocarbon vapor was mixed in the sewage of a factory and discharged into the sewer, so that the hydrocarbon vapor overflowed from the sewage gathered in the factory and exploded when it met the fire source

in the process of gas absorption and desorption, if the absorbed flammable gas or sewage containing flammable liquid (absorbent modifier) is discharged into the sewer, when the temperature rises, these flammable gases will be desorbed, and the flammable liquid will vaporize and escape. It is reported that in the process of absorbing hydrogen chloride in a chlor alkali plant, due to the insufficient thickness of the liquid seal at the liquid outlet of the absorption tower, the explosive gas and hydrochloric acid enter the sewer system of acid water together. In this system, the desorbed gas and air form an explosive mixture and explode

the sewage washed and washed often contains a variety of fire hazardous substances. This kind of sewage is also the source of explosive mixture of steam (or gas) and air in the sewer system

    1. 2. Hazardous substances are generated by easy mixing reaction

various substances discharged into the sewer interact, which may generate other flammable and explosive products. For example, the washing liquid discharged from the process equipment and the sewage washing the ground or when the valve tip and the hole are not tightly closed often contain substances with high chemical activity and low contact properties with each other; When they are mixed in the sewer, they will form explosive substances, which are easy to decompose into oxidized substances or even spontaneous combustion substances when heated. These substances often accumulate on the well wall and pipe wall and become dry materials, posing potential hazards. When alkali sulfide waste liquid and acidic sewage flow into the sewer, hydrogen sulfide flammable gas will be produced. Hydrogen peroxide and acetone in a factory were discharged into the sewer at the same time, and acetone peroxide was generated, resulting in the explosion of acetone peroxide in the sewer. After the flushing sewage containing ammonium nitrite, ammonium nitrate and other salts is discharged into the sewer, there is also a great potential explosion risk, because the chemical property of ammonium nitrite crystal is extremely unstable

    1. 3. It is easy to cause the spread of fire

the sewer system runs through the whole enterprise area, and the fire or explosion often spreads along the sewer system, leading to chain destruction. On January 28, 1984, the sewer of wenchongkou chemical plant in Maoming City, Guangdong Province exploded, and five sections of the whole process were destroyed. The explosion lasted for 8 minutes, forming a "tongue of fire" about 500m long. On June 27th, 1985, an explosion occurred in an upper waterway in Chongqing, involving 1 × 106 m 2。 A large number of houses were in ruins. 26 people were killed, hundreds injured and 91 seriously injured in the accident. Such a serious accident is rare since the founding of the people's Republic of China

    1. 4. There is a high probability of ignition sources

the common ignition sources in the sewer system are: mechanical impact and friction sparks during cleaning and maintenance; Sparks generated during welding near sewage wells and clarifier facilities; Burning cigarette butts, sparks in the vehicle exhaust pipe, etc

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