Prevention and disposal of disasters and accidents

Prevention and disposal of disasters and accidents caused by four kinds of chemical gases

at 17:57 on April 16, 2004, Chongqing Tianyuan Chemical Plant had a chlorine leak and explosion, 9 people were killed and missing, 150000 people were evacuated, and the main urban area of Chongqing was threatened by chlorine for more than 60 hours

on September 15, 2003, an ammonia leak occurred in the underground cold storage of a hotel in Jingmen City, Hubei Province. Although the officers and soldiers of the Jingmen fire brigade worked hard to rescue it, no casualties were caused, but the residents in a wide range of surrounding areas could not live normally for dozens of hours

in daily life, disasters and accidents caused by the leakage of gas and liquefied petroleum gas are even more numerous

chlorine, ammonia, coal gas and liquefied petroleum gas are widely used in chemical industry or daily life. For example, chlorine is not only an important raw material for manufacturing pesticides, plastics, rubber and synthetic fibers, but also a bleaching agent and disinfectant. It is widely used in daily life (at present, chlorine is the main raw material for the disinfection of drinking water in urban waterworks); Ammonia is widely used in the production of ammonium salt, nitrogen fertilizer, and refrigeration places; Coal gas and liquefied petroleum gas are the main fuels for urban household life. These four gases are toxic, and once leaked, they will cause disasters and accidents, with unimaginable consequences. Therefore, mastering the physical and chemical properties of these four gases and doing a good job in the prevention and disposal of these four gas disasters and accidents has become a topic that every city needs to face. This paper summarizes the relevant physical and chemical properties of chlorine, ammonia, coal gas and liquefied petroleum gas, analyzes the risk of disasters and accidents caused by them, and puts forward targeted measures on how to prevent and deal with them, which is only for reference of peers

[physical and chemical properties]

I. physical properties

1. Ammonia (NH3): colorless, with pungent odor. Under appropriate pressure, it can be liquefied into liquid ammonia and release a lot of heat at the same time. When the pressure decreases, it will be vaporized and escape, and absorb a lot of heat at the same time. It is easily soluble in water, ethanol and ether, and the aqueous solution is alkaline. Toxic, the maximum allowable concentration per cubic meter of air is 30 mg. It is lighter than air, with a relative density of 0.817 (-79 ℃), a melting point of - 77.7 ℃, a boiling point of - 33.5 ℃, an explosion limit of 15.7% to 27.4%, and the most easily ignited concentration of 17%

2. Gas: colorless, with special odor. It is easy to burn, and the combustion flame temperature is 900~2000 ℃. Highly toxic, mainly consisting of olefins, alkanes, aromatics, hydrogen, carbon monoxide, etc. The spontaneous combustion point is 648.9 ℃, the explosion limit is 4.5% - 40%, and the most easily ignited concentration is 1. According to the company's introduction, it is 5% - 21%, and the most easily propagated concentration is 18%

3. Liquefied petroleum gas: colorless (or yellowish brown liquid), with special odor. Toxic, mainly composed of propane, butane and isobutane. It is in gaseous state at normal temperature, 1.5~2 times heavier than air, and the boiling point in liquid state is - 47 ℃ ~0.57 ℃. It volatilizes into gas from liquid state, and the volume expands 250 times. The total vaporization volume of 1kg liquefied gas can reach 500 liters, which can form 25 cubic meters of explosive gas. The flash point is - 104 ℃ ~ - 67 ℃, the ignition temperature is 445 ℃ ~497 ℃, the ignition energy is 0.175~0.38mj, the explosion limit is 2%~10%, and the explosion power is 4~10 times that of the equivalent TNT explosive

4. Chlorine (Cl2): yellow green, with pungent smell. It is highly toxic, with a relative density of 2.49, which is heavier than air. Explosion limit 11% - 94.5% (in H2),

II. Chemical properties

the composition of coal gas and liquefied petroleum gas is complex, and the chemical properties are not very active. The chemical properties of ammonia are of little significance in this paper. This paper will focus on summarizing the chemical properties of chlorine

the chemical properties of chlorine are very active and can react with a variety of substances. Its main chemical properties include the following aspects:

(1) reaction with water. Chlorine reacts with water to produce hydrochloric acid and hypochlorous acid. Hypochlorous acid is a strong oxidizing acid, which has good disinfection and sterilization effect. The reaction equation is: cl2+h2=hcl+hclo

(2). It reacts with combustible gases. Chlorine can react with some combustible gases that are mostly used as laboratory materials by 2,3-bdo. For example, when hydrogen is mixed with chlorine, a violent explosion reaction can occur under light conditions. The reaction equation is: h2+cl2=2hcl

(3) react with alkali. Chlorine is an acidic gas, which can neutralize with alkali. For example, chlorine reacts with hydrated lime. The reaction equation is: 2cl2+2ca (OH) 2=ca (CLO) 2+cacl2+2h2o

(4). It reacts with metals. Chlorine can react with almost all metals under heating conditions

(5) react with nonmetals. Chlorine can react with almost all nonmetals except halogen

(6) react with organic matter. Chlorine can react with various unsaturated hydrocarbons and alkanes in addition or substitution. For example, chlorine can react with ethylene in addition. The reaction equation is: cl2+ch2=ch2 → clch2 - clch2

[disaster risk]

these four gases are toxic gases. When people absorb a small amount of these gases, their lives will be in danger. Ammonia, coal gas and liquefied gas should solve this problem. It is easy to burn. In case of open fire or high heat, it can cause combustion and explosion. Once explosive combustion occurs, it will be very difficult to control and bring disastrous consequences. Although chlorine cannot burn in air, it can support combustion. Generally, combustibles can burn in chlorine as in air. Chlorine can explode with many chemicals such as acetylene, ammonia, hydrogen, metal powder, etc. Chlorine is also an acidic gas, which has a strong corrosive effect on most metals and nonmetals. Once these four gases leak, they will cause great harm

[prevention of disasters and accidents]

configure according to the physical and chemical properties of these four gases according to customer needs; 3. The use or travel size of the space structure of the experimental machine can be specially customized according to the user's requirements. The occurrence of its disastrous accidents can be prevented from the following six aspects:

1. When the four gases are heated, the pressure in the cylinder increases and the danger increases, so its steel cylinders should be stored in a cool, dry, well ventilated non combustible structure warehouse, away from fire and heat sources, to prevent direct sunlight

2. Wear the safety helmet and shockproof rubber ring of the steel cylinder during handling to avoid rolling and impact and prevent the container from being damaged. At ordinary times, wipe the valve with soapy water, check whether the valve leaks, and take remedial measures in time

3. The building specially storing these gas cylinders should be equipped with a simple sprinkler. In case of leakage, the water sprinkler can be turned on to dilute or dissolve these gases

4. Chlorine cylinders should be isolated from combustibles, organics or other oxidizing substances, and stored in special warehouses. Special attention should be paid to isolating them from reactive substances, such as acetylene, ammonia, hydrogen, metal powder, etc

5. The building specially storing these gas cylinders should have good fire prevention measures and fire-fighting facilities to prevent these gases from burning and explosion due to building fire

6. Places specially storing these gases should be equipped with air (oxygen) respirators, special gas masks, rubber boots, gloves, etc., to provide reliable rescue equipment in case of accidents