Prevention and control of handling accidents of th

Prevention and control of accidents in hazardous chemicals handling operations

with the implementation of China's economic development strategy along the river and coastal areas, the demand for hazardous chemicals is increasing. Due to its low cost, environmental protection and large transportation volume, waterway transportation has become the main mode of dangerous chemicals transportation. The transportation of dangerous chemicals in the Yangtze River trunk line is 130 million tons/year, with 281 kinds of transportation varieties, including about 128 kinds of liquid dangerous goods in bulk, 144 kinds of solid packaged dangerous goods and 9 kinds of liquefied gases

the safety management of the transportation of dangerous goods on water mainly includes three main links: navigation, berthing and unloading, which are characterized by wide measurement range, high accuracy and fast response. The most problematic link is the loading and unloading operation of the ship dock (including the transfer operation). In the process of unloading, most of the media are volatile, flammable, explosive and toxic substances. Once leaked, it is very easy to cause major fires, explosions or pollution events. Therefore, it is very important to pay attention to the safety of ship loading and unloading at the wharf and ensure the safety of chemical terminals and ships. At present, potential safety hazards are prominent, and accidents and dangerous situations occur from time to time. For example, on April 21, 2002, a styrene overflow accident occurred on the Panamanian ship "wuse" at the Chimei wharf of Zhenjiang Dagang, which polluted the water body near the wharf to a certain extent, causing the water supply in the Dagang area to be suspended for 5 hours

mastering the physical and chemical properties of goods is closely related to the safety control of loading and unloading production. In order to ensure the safety of the whole process of ship shore loading and unloading, we should select a scientific loading and unloading process from the physical and chemical characteristics of the unloaded goods, strictly abide by the operating procedures, comprehensively analyze the precautions in the unloading production process, and do a good job in scientific control, so as to ensure personal safety, cargo safety, equipment safety, environmental safety, and provide a reliable guarantee for the safety of dangerous chemical loading and unloading production

I. physical and chemical characteristics of hazardous chemicals

1. Flammability and explosion

its main technical indicators include flash point, explosion limit, etc. Dangerous goods are unloaded on the dock, otherwise there is a risk of electric shock or damage to the machine. A considerable part of the goods are class a fire dangerous goods. The flash point of many varieties is lower than 23 ℃, and the explosion range is more than 20% when polished. Once exposed to ignition energy, it will flash and explode

2. Easy evaporation

fire hazard class A and B chemicals are mostly liquids with high vapor pressure, which are easy to produce the minimum amount of steam required to cause combustion. The greater the steam pressure, the greater the risk of combustion and explosion

3, easy to flow, diffusivity

liquid chemicals generally have low viscosity and fluidity. After leakage, they are easy to flow and diffuse, and the flow and diffusion with low viscosity are enhanced. On the other hand, the steam of chemicals is heavier than air, which is easy to accumulate in low-lying places such as ship cabins, wharf surfaces, ditches, sewers and pits, and spread to the distance with the wind. Often in unexpected places, the unit is equipped with load measurement and load feedback devices, which will cause fire and explosion accidents when encountering fire sources

4. Thermal expansion

the volume of flammable liquid has the characteristics of thermal expansion and cold contraction. After liquid chemicals are heated, the temperature rises, the volume expands, and the pressure increases, which will cause the container to burst in serious cases. On the other hand, when the hot liquid cools, it will cause volume contraction, which will make the container pressurized and easy to be crushed by atmospheric pressure

5. It is easy to accumulate electrostatic charge

all kinds of combustible liquids are poor conductors of electricity in the pure state, and static electricity will be generated when they are impacted by vibration and the walls of cars, ships and tanks, as well as when they are transported by high-speed pipelines, especially rubber hoses, whose walls and chemicals each have charges with opposite polarity, so that the electrostatic field strength and liquid level potential accumulated can often be as high as 10000 volts

6. Health hazard

most dangerous chemicals are toxic and easy to cause health damage to human body. There are also X and Y substances. The main ways of invasion are inhalation, ingestion or skin absorption. Once such substances leak, the drinking water source will be polluted, and the consequences will be unimaginable

7. Reactivity with other substances

it is mainly considered that two incompatible liquid goods or substances contact and penetrate each other, causing violent oxidation reaction, emitting flammable gas and heat, thus causing combustion or explosion; Some goods also react with water or air. Put forward strict control conditions and precautions for materials, tools, equipment and facilities and cargo containers that directly or indirectly contact the goods in the process of loading, unloading, storage and transportation. Such as avoiding acid, alkali, oxidant, active metal, anhydrous chloride, asbestos, peroxide of iron or aluminum, alkali metal, hydroxide, etc

8. Polymerization hazard

mastering the polymerization hazard of goods and adding stabilizers are important safety technologies to ensure the management of goods in loading, unloading, storage and transportation. Therefore, when receiving such goods, it is necessary to verify in advance: the name and quantity of the stabilizer added; Addition date and expiry date of stabilizer; Ensure any temperature limit of the effective period of the stabilizer; Measures to be taken when the sailing or transportation period exceeds the validity period of the stabilizer