Petrochemical fire accidents and disposal countermeasures

I. Causes of petrochemical fire accidents

 

    In the case of fire accidents in chemical companies, large quantities of toxic and harmful gases (or liquids) are generally lost. Because of their toxic, diffusible, and flammable explosion characteristics, they are likely to cause large-scale pollution in the accident area and a large number of casualties. Large and medium cities are particularly serious. Investigating its causes, chemical fire accidents mainly occur in the following three situations: 1. Operators operate illegally. Chemical production, storage and transportation have strict operating procedures, and accidents may occur if regulations are violated. 2. Failure of the enterprise equipment itself. The production of chemical products requires high temperature, high pressure, and low pressure. In addition, many raw materials and products are highly corrosive, which can easily cause the damage of various pipes, valves, towers, and cylinders, resulting in safety risks such as running, dripping, dripping, and leaking toxic substances. . 3. Unpredictable unexpected factors. This type of accident is caused by accidental power outage and water outage in the chemical production process, resulting in accidents caused by uncontrolled chemical reactions, and leakage of toxic materials during transportation. Chemical accidents caused by unexpected factors often occur, and the harm is serious.

 

    Second, correctly identify the type of petrochemical fire

 

    There are three general types of petrochemical fires. 1. Stable combustion fire. That is, the gas or flammable liquid presents a diffuse combustion pattern at the leak or open opening of its closed container, and the flame has no obvious fluctuations, just like a lighted torch. For example, the fire of liquefied petroleum gas on the top of light oil tanks, liquefied petroleum gas tanks, beeper valves, measuring holes, and safety valves, the flame of the liquefied petroleum gas is vertically upward, and the combustion range is also limited to smaller openings. 2. Explosive fire. The characteristics of this type of fire and explosion are that they explode first and then burn; some burn first and then explode; some only explode and do not burn. 3. Boiling overflow fire. Generally, a huge fire column is formed, which can reach 70 to 80 meters, and the oil fire rain that is emitted in the downwind direction can reach about 120 meters. This kind of fire is easy to cause casualties of extinguishers, and it is easy to form large-area three-dimensional combustion, which is the most difficult to extinguish and extinguish.

 

    Third, the characteristics of petrochemical fire accidents

 

    A petrochemical fire is different from a general fire accident. It has the following characteristics:

 

    1. Large explosion danger. First, there are a large number of flammable raw materials or products stored in the equipment and pipelines of petrochemical production and storage sites. Leaks and explosions or thermal expansion easily cause physical explosions; secondly, the high degree of continuity of the production equipment is easy to form continuous explosions; finally in the fire Incorrect rescue procedures may cause multiple explosions.

 

    2. The fire has developed rapidly. According to fire fighting practice calculations, when a petrochemical fire occurs, the flame's straight-line propagation speed can reach 2 to 3 meters per second. At the same time, its burning speed is also very fast, for example: gasoline fire can reach 80.9 kg / m2 * hour, benzene can reach 165.4kg / m2 * hour. Burning and exploding at a fast rate is extremely difficult.

 

    3. It is easy to form three-dimensional large-area combustion. When a fire occurs in a building or structure that produces flammable and explosive liquids and gases, it is easy to cause the fire to cause three-dimensional combustion due to the interrelationship between the structure and the structure. In a gas fire, the proportion of gas larger than air is from the top. When it spreads, it will form a three-dimensional combustion when it encounters a fire source; flammable and explosive liquids are affected by high temperature or thermal radiation, and the volatilized vapor may drift and spread with the wind from the bottom up. When the fire source flows or splashes, It is also easy to form a three-dimensional combustion phenomenon.

 

    4. Prone to re-ignition and re-explosion. In a petrochemical fire, after a gas or oil fire is extinguished, if it is not properly disposed of in a timely manner, the residual will still burn or explode again. This must be paid great attention in fighting the fire.

 

    5. The harm is huge. Petrochemical fires burn quickly, have high calorific value, and have strong heat radiation from the fire field, which can easily cause rescue personnel to be injured. In addition, the leakage and spread of toxic substances and the splashing and flowing of flammable and explosive materials form a large-area, three-dimensional or multi-fire ignition, which expands and aggravates the scope and extent of disasters. Its toxic gases are also likely to cause casualties for rescue personnel.

 

    Formulation of emergency rescue plan

 

    Making accurate and detailed plans can provide a reliable theoretical basis for handling chemical accidents and save a lot of time for collecting relevant information from the scene. A complete plan, the basis of the rescue plan is formulated first, mainly including the situation of the rescue organization system, relevant legal provisions and industry regulations. Secondly, clarify the composition, responsibilities, division of labor, contact methods, and action requirements of emergency rescue organizations. Finally, the chemical accident unit name, address, scale, production, storage, type of chemical used, hazardous characteristics, process flow and technical requirements, etc., the location of the chemical accident source, the name of the toxic and hazardous article, its origin, and possible release Source strength, as well as hazard direction, hazard area division, etc., corresponding technical requirements in terms of disinfection, plugging, protection, detection, etc., personnel distribution in nearby areas, traffic, construction, water sources, weather and other conditions, fire brigade rescue and rescue Distribution and coordination of capabilities and social rescue forces.

 

    A good plan is like the fire brigade is equipped with advanced weapons and equipment, combined with the characteristics of chemical accident rescue and rescue, and conducting scientific and technical training, which greatly improves the fire brigade's high-quality and rescue and rescue capabilities. The first is to solidly learn basic theoretical knowledge. Organize a large number of officers and soldiers to learn about chemical knowledge, combustion knowledge and knowledge of chemical dangerous goods, especially the hazardous characteristics, combustion, and explosion characteristics of chemical dangerous goods involved in urban production, storage, transportation and distribution units. The second is to elaborate key training courses. Aiming at some characteristics of chemical accidents, some key courses in handling and protection were drawn up to improve the army's ability to adapt to actual rescue and rescue operations, and to highlight the training of troops in protection and rescue. Learn protective knowledge, learn to use protective equipment, conduct training through accident areas, accident areas, conduct process disposal, offensive and evacuation training, familiarize with protective actions and master disinfection and first aid methods. The third is to carry out fire drills carefully. The drill is a practical training for organizations and personnel involved in rescue operations according to the set accident conditions. The exercise can experience the coordination ability between organizational systems; the pertinence of the plan can be tested; whether each rescue force and technical force can meet the needs of actual combat. The fire brigade often undertakes rescue and fire fighting tasks in the rescue and rescue work of chemical accidents, and it is necessary to carry out professional drills frequently.

 

    V. Methods of Fighting Petrochemical Fires

 

    Petrochemical fires have the characteristics of rapid spread of fire and large burning area. Therefore, when organizing and directing fire fighting, it is necessary to implement the principle of first control and then eliminate according to its fire characteristics, flexibly use fire fighting tactics, and effectively extinguish fires. According to different burning materials and fire situations, corresponding tactical measures must be taken to extinguish the fire quickly and safely.

 

    1. A scientific plan to make faster. The key to successfully extinguishing petrochemical fires is planning, that is, conducting fire control according to scientific plans. For key parts of petrochemical enterprises, based on investigations and tactical drills, it is necessary to formulate a practical combat fire fighting plan, and the units participating in the battle can make the commander clear about the combat plan; the driver must be clear about the driving route and parking location. ; The combatants are clear about their tasks; the water supply crews are clear about the situation of the water source. When a fire broke out in a unit or part of a petrochemical enterprise, it was possible to act as planned. First, the dispatch force implements planned command. According to the plan, all required fire-fighting forces can be deployed to the fire field at one time; second, commanders at all levels can dispatch their own unit's driving routes and combat operations after the scene according to the plan's requirements, and target the fire situation. Proactively conduct on-the-spot command, do well in coordinated operations, and complete various combat tasks together. In this way, it is possible to dispatch forces quickly, reach the fire scene quickly, fire reconnaissance and combat unfold quickly, and be methodically engaged in combat, in line with the characteristics of the rapid development of petrochemical fires. For the fire fighting of petrochemical industry, it is very important to have fast combat command and combat action. To extinguish petrochemical fires, only by commanding according to the plan can we fundamentally overcome the passive situation of dispatching fire extinguishing forces; we can give full play to the enthusiasm and initiative of fire commanders at all levels, and consciously direct the operations of our units to prevent The chief commander of the fire field was busy on the spot, and lost sight of each other. The commander of the brigade passively listened to the order, the scene was disordered, and the fighters were delayed. Only by implementing planned command can we be quick without chaos, win time, seize favorable fighters, and use planned fast actions to subdue the rapid development of petrochemical fires and make quick decisions.

 

    2. Stop the fire and prevent it from spreading. Petrochemical fires are mostly caused by fires in materials, production equipment and parts of buildings. When fighting this kind of fire, the primary task is to control the development of the fire and eliminate the spread of the fire, which is to deploy capable forces to intercept the fire in the main aspect of the spread of the fire. Prevent spread. If the materials in the petrochemical production and storage equipment catch fire, try to cool the building or tank structure, or reduce the combustion intensity, prevent ignition of the building, and expand the fire. Similarly, when a building or an oil tank catches fire, the fire will directly threaten the production equipment and its internal materials. In this case, we should concentrate our efforts to eliminate the threat of the fire to production and storage equipment and stop the fire from spreading. In addition, in petrochemical fires, often due to the high temperature or explosion of storage tanks, containers and pipelines, a large number of flammable and combustible liquids are scattered and burned when the fracture occurs, which makes the fire quickly expand and spread. In order to stop the dispersion of the combustion, methods such as cutting off the source of the burning liquid, building a dike or diversion can be adopted to block the development of the fire and create favorable conditions for extinguishing the fire.

 

    3. Grasp the key points and eliminate dangerous situations. According to the characteristics of petrochemical fires that are prone to explosions, the fire brigade must quickly find out the situation when it reaches the fire field. For the fire field that is exploding, it is necessary to select favorable terrain and features and make a strong breakthrough; According to the nature of the explosive, use strong water flow or other fire extinguishing agents to eliminate the ignition source that is causing the explosion, and at the same time cool the unexploded material or equipment to exclude the danger of explosion; when the explosive material or equipment may explode due to the impact of the fire, the organization must Assault forces, adopt key breakthrough tactics, break through the blockade of pyrotechnics, control the fire, eliminate the threat of fire to explosive substances or equipment, and at the same time, try to cool and evacuate the threatened materials, create safe conditions for fire suppression, and then organize forces Fight the fire.

 

    4. Divide and encircle. When a fire occurs in a storage tank, a reactor, or a pipeline, it is first burned in a tank or a certain section. With the development of combustion, the fire spreads to adjacent tanks or equipment. In view of this burning characteristic, a split-and-enclosing tactic should be adopted, focusing on surrounding the combustion tank or reactor, and protecting adjacent tanks, reactors, and equipment. If several tanks or reactors are burning, the burning tanks or reactors must be divided and surrounded according to the fire extinguishing force and the specific conditions of the fire field, and the fire should be extinguished at the same time. When extinguishing torches burning on raw material storage tanks, reactors and pipes, the fire field commander must make all preparations for fire suppression while deploying forces to cool the equipment. First of all, the water supply work of the fire field must be organized, and the lean water gunners should be selected to be responsible for the fire extinguishing and cover work to form a situation of surrounding each torch. After the water gunner entered the fire fighting position to test the water, the commander uniformly issued an order to extinguish the fire. There are several specific methods for extinguishing fire: under the cover of water by a water gunner, the combatant or worker closes the valve of the gas pipeline; the organization covers the suffocation; cuts off the flame with dense water flow, separates the combustible gas from the flame, and extinguishes the flame formed by the extinguishing torch. During the fire extinguishing process, it is necessary to keep cooling the heated equipment to prevent the production and storage equipment from being damaged and cause the fire to spread and expand.