Vinyl chloride is the industrial production of polyvinyl chloride (PVC) raw materials, and other chemicals copolymerization, can also be used to make dyes and spices of the extraction agent, as well as refrigerant, etc., the domestic production of vinyl chloride by calcium carbide method to make PVC, accounting for about 60% of the capacity of PVC.
Vinyl chloride is a colorless, ether-like odor gas, boiling point -13.3℃, gas density 2.15g/L, saturated vapor pressure 346.53kPa(25℃), flash point -78℃, explosion limit 3.6% ~ 31.0% (volume ratio), regarded as liquefied hydrocarbons for control, its low flash point, low explosive limit, easy to explode. And vinyl chloride vapor is heavier than air, spread along the ground and easy to accumulate in low-lying places, in case of fire source will ignite back.
At the same time, vinyl chloride is also highly toxic chemicals, set acute and chronic toxicity, carcinogenicity, teratogenicity, reproductive toxicity, environmental harm, soil enrichment in one of the "hexagon warrior". The acute toxicity of vinyl chloride is anesthetic effect, mild poisoning patients appear dizziness, chest tightness, lethargy, staggering gait, etc., serious poisoning may cause coma, convulsion, and even death; Chronic toxicity includes liver cancer and cancers of the brain, lung, blood and lymphatic system.
Because the combustion of vinyl chloride may form dioxins, phosgenes and other highly toxic chemicals, so the disposal of vinyl chloride leakage is very difficult. The vinyl chloride spherical tank (or storage tank) of domestic enterprises and the safety valve of the reactor involving vinyl chloride and other equipment are mostly taken high point direct discharge into the atmosphere after jumping. In addition, the transportation volume of highly toxic chemicals, liquefied hydrocarbons and so on is large. If traffic accidents or leaks occur during transportation, how to effectively dispose of them is also extremely difficult. Therefore, the leakage accident of vinyl chloride in Ohio sounded the alarm again for the risk control of vinyl chloride in China, as well as the risk control of transportation of highly toxic chemicals and liquefied hydrocarbons. The author makes the following two suggestions regarding the leakage of vinyl chloride in Ohio.
1
Strengthen the risk control in the process of vinyl chloride production
In recent years, there were two leakage accidents of vinyl chloride gas cabinet in China. The two accidents were separated by less than half a year, which aroused great attention of the society. Therefore, vinyl chloride is included in the Catalogue of Dangerous Chemicals under Special Control (first Edition), and the only dangerous chemical to be strengthened control is vinyl chloride in the Implementation Plan of the Three-year Special Rectification Action for the Safety of Dangerous Chemicals. It requires that "PVC production enterprises shall comply with the Safety Operation Regulations of Vinyl Chloride Gas Cabinet and the Improvement Plan of Safety Protection Measures for Vinyl Chloride Gas Cabinet". Further improve the safety management measures of vinyl chloride gas cabinet, improve the intrinsic safety level ". Therefore, enterprises should in accordance with the "calcium carbide acetylene production of vinyl chloride safety technical Regulations" (GB 14544-2008) requirements, strengthen the risk control of vinyl chloride production process, according to the "vinyl chloride gas cabinet safety operation Regulations" (CCASC1001-2020), improve the level of automatic control of vinyl chloride gas cabinet, Equipped with safety instrument system and emergency shut-off valve.
2
We will strengthen risk control over the transportation of highly toxic chemicals and liquefied hydrocarbons
A glimpse of the leopard is visible. The occurrence of the accident and the chaotic handling of the accident exposed the poor control of the transportation of dangerous chemicals and emergency treatment in the United States. Although domestic vinyl chloride monomer production enterprises produce more for their own use, and road transportation is less, a large amount of vinyl chloride monomer needs to be imported in China every year, and there are risks of pipeline transportation and road transportation. At the same time, the transportation volume of liquefied hydrocarbon is large and the risk is high.
In recent years, there have been a number of highly toxic chemical transportation leakage accidents, such as: The leakage accident of "6•5" hydrofluoric acid tank truck in Yulin in 2015, the leakage accident of anhydrous hydrogen fluoride of "8•3" tank truck in Luoyang in 2015, the leakage accident of hydrofluoric acid of "4•27" tank truck in Changzhou in 2021, and the leakage accident of "8•29" liquid chlorine tank truck of Ronghui Chemical Industry in Wuhu in 2020. Therefore, the transportation of dangerous chemicals, leakage disposal and so on can not be taken lightly.
There have been a number of leakage accidents in the transportation of liquefied hydrocarbon in China. In 2020, there was a major deflagellation accident in Shenhai Expressway in Wenling City, Taizhou, which caused 20 deaths and 175 people were hospitalized, 24 of whom were seriously injured.
Therefore, for the transport of highly toxic chemicals, liquefied hydrocarbons to strengthen supervision, strengthen the training of transport personnel, improve safety awareness. Supervision and inspection of transportation enterprises of hazardous chemicals should be done well, and supervision and administration of operators of transportation enterprises, transportation and escort personnel should be strengthened. Transportation and escort personnel transporting hazardous chemicals must obtain transportation qualification certificates for the corresponding category of hazardous chemicals, and use special containers and special vehicles that meet the national standards to carry and transport them. Transport vehicles shall be marked for the transport of dangerous goods and equipped with satellite positioning devices with driving record function. Without the approval of the public security organ, the transport vehicles shall not enter the areas where the transport vehicles of hazardous chemicals are restricted. Stay away from fire during transportation. It is forbidden to stay in residential areas and densely populated areas. When parking, someone should be supervised to prevent the expansion of the accident caused by leakage. It is necessary to establish an early warning mechanism and an emergency rescue mechanism for transportation accidents of hazardous chemicals, formulate and perfect emergency response plans, and quickly start accident early warning and response procedures when a major transportation leakage accident occurs, and timely release relevant information to enhance public awareness of prevention. It is necessary to improve the construction of emergency rescue evacuation channels, let the public be familiar with the physical knowledge of dangerous chemicals, and master certain rescue skills, improve the public's ability to rescue each other, and effectively prevent heavy casualties and property losses when emergencies occur.
Principle of vinyl chloride emergency disposal
First aid measure
Inhalation: Quickly remove from the scene to fresh air. Keep your airway clear. If breathing is difficult, give oxygen. If breathing stops, give artificial respiration immediately. Seek medical attention.
Skin contact: Immediately remove contaminated clothing and rinse skin thoroughly with soapy water and clean water. Seek medical attention.
Eye contact: Lift eyelid and rinse with running water or saline. Seek medical attention.
Fire extinguishing method
Cut off the air supply. If the air source cannot be cut off, it is not allowed to extinguish the flame at the leak. Spray water to cool the container and move it away from the fire and into the open as much as possible. Extinguishing agent: mist water, foam, carbon dioxide.
Leakage emergency treatment
Eliminate all ignition sources. Delimit the warning zone according to the area affected by the gas, and evacuate irrelevant personnel from the crosswind or upwind to the safety zone. It is recommended that emergency personnel wear positive pressure self-contained air breathing apparatus and anti-static clothes. Wear antistatic and cold-proof clothes when liquefied gas leaks. All equipment used during the operation should be connected to the site. Do not touch or cross spills. Cut off the source of leakage as much as possible. If possible, turn the container so that it escapes gas rather than liquid. The spray water suppresses the vapor or changes the direction of the vapor cloud to prevent water from touching the spill. Do not use water to directly impact the leak or leak source. Prevent gas diffusion through sewers, ventilation systems and enclosed Spaces. Isolate the leak zone until the gas dissipates. As an emergency precaution, the leak isolation distance is at least 100m. If a large amount of leakage, the initial evacuation distance downwind should be at least 800m.
