Fire accidents in the petrochemical industry and their handling countermeasures

I. Causes of Petrochemical Fire Accidents

Fire accidents in chemical enterprises usually result from the large-scale loss of toxic and harmful gases (or liquids). Due to their high toxicity, easy diffusion and flammability and explosiveness, they can easily cause large-scale pollution in the accident area and a large number of casualties, which is particularly serious in densely populated large and medium-sized cities. The main reasons for the occurrence of chemical fire accidents are as follows: 1. Operators violate operating procedures. Chemical production and storage and transportation have strict operating procedures. Once violations occur, accidents may happen. 2. Faults of the enterprise's equipment itself. The production of chemical products requires high temperature, high pressure and low pressure. Moreover, many raw materials and products are highly corrosive, which can easily lead to the corrosion and damage of various pipes, valves, towers and cylinders, thus causing safety hazards such as the leakage, overflow, dripping and seepage of toxic substances. 3. It is an unpredictable and unexpected factor. This type of accident occurs when chemical reactions get out of control due to sudden power or water outages in the chemical production process, or when toxic substances are overturned or explode during transportation, resulting in leakage accidents. Chemical accidents caused by unexpected factors occur from time to time and pose serious hazards.

Second, accurately identify the types of fires in petrochemicals

There are generally three forms of petrochemical fires. 1. Stable combustion type fire. Flammable gases or flammable liquids present a diffusive combustion form at the leakage or opening of their sealed containers, with no obvious fluctuation of the flame, just like a lit torch. For instance, in the case of a fire involving liquefied petroleum gas at the top of light oil tanks or liquefied petroleum gas tanks, such as the valve, measurement hole, and safety valve, the flame is vertically upward, and the burning area is only limited to a small opening. 2. Explosive fire. The characteristics of this type of fire explosion are that some explode first and then burn. Some burn first and then explode. Some only explode but do not burn. 3. Boiling and overflowing fire. Generally, huge fire columns are formed, which can reach a height of 70 to 80 meters, and the oil fire rain ejected from the downwind can reach about 120 meters. This kind of fire is prone to cause casualties among the firefighters, and at the same time, it is likely to cause large-scale three-dimensional combustion, which is both harmful and difficult to extinguish.

Iii. Characteristics of Fire Accidents in Petrochemicals

Petrochemical fires are different from ordinary fire accidents. They have the following characteristics:

1. High explosion risk. Firstly, the equipment and pipelines in petrochemical production and storage sites contain a large amount of flammable raw materials or products. In case of leakage and explosion or expansion due to heat, physical explosions are likely to occur. Secondly, the high continuity of production facilities makes it easy for continuous explosions to occur. In the end, if the fire-fighting procedures are incorrect, multiple explosions may occur.

2. The fire spread rapidly. Based on the practical calculation of fire fighting, when a fire occurs in the petrochemical industry, the straight-line spread speed of the flames can reach 2 to 3 meters per second. At the same time, its burning speed is also very fast. For instance, gasoline fires can reach 80.9 kilograms per square meter per hour, and benzene fires can reach 165.4 kilograms per square meter per hour. The speed of combustion and explosion is so fast that it is hard to guard against.

3. It is easy to form a large-scale three-dimensional combustion. When a fire breaks out in a building or structure that produces and stores flammable and explosive liquids and gases, due to the interrelated influence among the buildings and structures, it is easy for the fire to cause three-dimensional combustion. In gas fires, gases with a specific gravity greater than that of air diffuse from top to bottom and will also form three-dimensional combustion when encountering a fire source. Flammable and explosive liquids, under the influence of high temperatures or thermal radiation, may emit vapors that float upward and spread with the wind. When encountering a fire source, they may cause flowing or splashing fires, and are also prone to three-dimensional combustion phenomena.

4. It is prone to re-ignition and re-explosion. In petrochemical fires, if gas or oil fires are not properly dealt with in a timely manner after being extinguished, the remaining fires may still catch fire or explode again. This point must be given high attention in fire fighting.

5. Extremely harmful. Petrochemical fires have a fast burning speed, high calorific value and strong heat radiation at the fire scene, which can easily cause injuries to firefighters. In addition, the leakage and diffusion of toxic substances and the splashing and flowing of flammable and explosive materials form large-scale, three-dimensional or multi-fire ignition, expanding and aggravating the scope and severity of the disaster. Moreover, the toxic gases are also prone to cause casualties among the rescue personnel.