In the early morning of November 4, Fujian Donggang Petrochemical Industry Co., Ltd. carried out the loading and unloading of C9-ldquo; Tiantong No. 1-rdquo; during the loading and unloading operation, due to aging and damage of hose gaskets, leakage occurred at the hose connecting the ship and the wharf, resulting in a total of 6.97 tons of C9 chemical leakage. Affected by the accident, the fishermen in the adjacent sea area suffered heavy losses. A large number of fishing rafts sank due to corrosion. The situation of dead fish in fish ponds was obvious, resulting in huge economic losses.
Since November 4, Quangang District Hospital has been receiving 52 people from Nanpu and Houlong coastal areas of Quangang District suspected of exposure to carbon nine leakage. The main complaints of these patients are: ldquo; physical discomfort after exposure to irritating gases - rdquo; and the main symptoms are dizziness, nausea, vomiting and pharyngeal discomfort.
So what is the carbon nine that attracted much attention? How does it leak?
What is carbon nine?
C-9, short for C-9 aromatics, is an aromatics fraction with 9 carbon atoms in the by-products of catalytic reforming and cracking of petroleum. Their boiling points are similar and it is difficult to separate further, so they are often used together in this way. The main components of C9 include various nine-carbon aliphatic hydrocarbons, cumene, n-propylbenzene, ethyl toluene, indene, mesitylene, meta-tritoluene and o-tritoluene.
We know that the most important use of petroleum is to extract gasoline and diesel. Generally speaking, the main component of gasoline is C5 ~ C8, while the main component of diesel is C10 ~ C12, so C9 is actually a kind of substance with boiling point between gasoline and diesel. If it is added to gasoline, it is easy to produce carbon deposit if it is not burned sufficiently. If it is added to diesel, there will be insufficient power, so its use is relatively embarrassing. Although some fuel engines can use C9, after all, it is far less popular than gasoline engines and diesel engines, so only to find other uses.
Carbon nine has an important link in processing: — — reforming. Carbon 9, which has just been cracked from petroleum, is mainly aliphatic hydrocarbons, i.e. substances without benzene rings. After reforming, these aliphatic hydrocarbons undergo aromatization reaction and become various aromatic substances, including cumene, toluene, trimethylbenzene and so on. C-9 aromatics accounted for 80%-90% of all reformed heavy aromatics, of which trimethylbenzene accounted for 50% and methylethylbenzene accounted for 20%-25%. At present, trimethylbenzene and mesitylene are mainly separated from refineries and used to prepare trimethylbenzene anhydride and pyromellitic dianhydride, which can be used in coatings, synthetic resins and so on.
In other words, there are actually two kinds of carbon 9, one is cracked carbon 9, the other is reformed carbon 9. The composition of the two kinds of substances is very different, and the harm to the environment is also different. According to the current situation, the leakage of carbon 9 in the Quangang spill should be relatively low toxicity pyrolysis carbon 9.
What is the harm of carbon nine?
Carbon 9 belongs to flammable dangerous goods, which can pollute water, soil and atmosphere, produce anesthesia and stimulation to human beings. Inhalation and exposure to high concentration of carbon 9 vapor have anesthesia and stimulation effects, which can cause eye, nose, throat and lung irritation, headache, dizziness and other symptoms of central nervous and upper respiratory tract stimulation. Long-term repeated contact can cause. Skin defatting. At the same time, the consumption of carbon and nine contaminated animal and plant seafood, as well as poisoning, carcinogenesis and other risks.
If cracked carbon 9 leaks, like gasoline and diesel oil, carbon 9 with lower water density will float on the water surface, which will cause anoxia in the aquaculture area of fishing grounds, eventually leading to fish death and economic losses to fishermen.
In this case, the conventional treatment method is to use asphalt felt for adsorption recovery. Of course, during the cleaning process, the low boiling point and large volatility of carbon nine will disperse into the air. In addition, some carbon nine floating to the corner can hardly be recycled. These carbon 9 residues after adsorption can only be treated by natural volatilization, which can cause persistent air pollution and eventually degrade naturally. This is why local residents continue to smell distinct odors.
Carbon nine is a good solvent, and some of the floats, foam and fishing nets used by fishermen are made up of organic matter. After soaking with carbon nine, these materials will be corroded by carbon nine. Although the relative toxicity of pyrolytic carbon 9 is not significant and there is no known risk of carcinogenesis, it is still a pollutant after it leaks out. Whether fish or shrimp, after the pollution, will absorb some toxic and harmful ingredients. Therefore, the relevant departments need to deal with the aquatic products in the adjacent sea areas to ensure that the aquatic products entering the public dining table are safe.
If the leakage is reconstituted carbon nine, that would be more trouble than cracking carbon nine.
The content of aromatic hydrocarbons in reformed carbon 9 is higher, and their odor is more special. They have an unpleasant aroma, which is obviously different from gasoline. Aromatics are relatively more active and more toxic. The carbon nine aromatics represented by cumene are more complex than aliphatic hydrocarbons.
Under the premise of light, most aromatic hydrocarbons are prone to some free radical reactions, resulting in complex by-products. In an environment rich in chlorine, such as the ocean, once carbon 9 leaks, some chlorinated aromatic hydrocarbons will inevitably be formed under the action of sunshine and sea water environment, such as dioxins, which made people feel discolored at that time. English is one of them.
How can we protect ourselves from accidents?
So, for villagers living near the leakage area of carbon nine, how should we effectively protect them?
Experts say that if local residents live close to the leak site, they need to wear masks containing activated carbon filters to avoid inhalation, and avoid eating contaminated animals, plants and seafood. Rinse your mouth as soon as you find it wrong. If you find abnormal or numb sensation of lips, mouth and tongue accompanied by headache and dizziness symptoms, you should see a doctor in time. If skin and clothes are exposed to C9, they can be washed with water first, then thoroughly cleaned with detergent and soap and consulted a doctor.
Although the official announcement of water quality has been qualified, the enrichment problem of carbon nine can not be ignored. The management of the involved waters is a long-term and systematic work. Related workersPersonnel must pay attention to prevent respiratory intake and skin contact pollution when cleaning.
Finally, it should be pointed out that the leakage of oil refining raw materials during transportation is a high occurrence accident. In addition to the corrosive nature of the oil itself, it is easy to dissolve the seals at the joints. Even the corrosion-resistant PTFE gaskets between flanges will swell under the long-term immersion of hydrocarbons, resulting in a decline in mechanical properties. Besides, the biggest hidden danger of raw material transportation lies in the disregard of employees' responsibility for production. The accident should be taken seriously by relevant departments and units. (Ke Huaihong Sun Yafei)