Firefighting forces deal with chemical dangerous goods leakage accident emergency rescue measures

The accident of chemical dangerous goods leakage refers to the serious leakage of chemical dangerous goods caused by the lack of design, illegal operations, and equipment failure during the production, transportation, storage, and use of chemical dangerous goods. Consequences of accidents. At present, with the rapid development of the chemical industry, a considerable amount of chemical dangerous goods are being produced or stored in warehouses of chemical companies in various parts of the country. A considerable amount of chlorine, ammonia, hydrogen fluoride, formaldehyde and other dangerous chemicals are used in chemical synthesis every day. In the production process, transport within the railway tanker and transportation within the trunk line, together with warfare, man-made destruction, and natural disasters, constitute a potential threat to the accidental leakage of urban chemical poisons. "Fire Protection Law of the People's Republic of China" clearly stipulates that the task of rescue of chemical dangerous goods shall be undertaken by the public security firefighting force. Therefore, it is an urgent task for firefighting teams to complete their rescue missions to study the characteristics and laws of chemical toxicant leakage accidents and clarify its impact and requirements on emergency assistance work. It also has important theoretical and practical significance.

First, how to adapt to the characteristics of leakage, poisonous, flammable and explosive chemicals dangerous goods

Chemical leaking substances are highly toxic. Such as: ammonia, gas, sulfur dioxide, benzene and homologues are toxic substances, phosgene, hydrogen cyanide, hydrogen fluoride, chlorine, formaldehyde, nitrogen dioxide and other highly toxic substances, the highest allowable concentration in the air below 30PPM, Among them, phosgene and hydrogen cyanide are still queued up by many countries as standard military agents. They are highly toxic and people inhale a high concentration of poisoned air and cause poisoning and even death. Most chemical industrial toxicants also have the characteristics of low boiling point, low ignition point, low flash point, and flammability. Such as: benzene, toluene, ethylbenzene, hydrogen cyanide, methanol and its flash point of less than 28 degrees Celsius; gas, liquefied petroleum gas, formaldehyde, acetylene and other mixed with the lower explosion limit of less than 10%, belonging to Class A fire hazard Sexual material. It can thus be seen that the on-site environment of chemical poison leakage accidents will be a dangerous environment where toxic gas and fire coexist and explosion and combustion coexist. Emergency Rescue Work In the face of this sinister environment, rescue workers are faced with the severe test of this life and death. The most pressing task is to solve the problem of “surmounting”. If you can't make it, you can't even reach the leak site. Talk about rescue. To "catch up", six issues must be resolved. First, the team must be leaner. That is to say, the rescue team must be leaner in preparation. Each city's public security fire brigade should establish at least a special service fire squadron of about 30 people. The second is that excellent quality and technology must be excellent. In other words, the team members have a spirit of devotion and courage, and everyone understands the theory, will be protected, and can master the special rescue ability to deal with various poisons. The third is to complete the equipment. That is, personal anti-drug equipment (air respirator, gas mask, full-enclosed protective clothing and flame-retardant clothing, etc.) is complete; rescue equipment (chemical dangerous goods rescue vehicle, detox exhaust equipment, rapid detection laboratory equipment, etc.) is complete; Be proper. That is, the commanding organizations at all levels and the commanding staff must command, command, and direct commands in a timely manner. Fifth, the rhythm of action must be decent. After arriving at the scene, the steps of reconnaissance, alert, and cover offense should be clear and appropriate. Sixth, safeguards should be sufficient. Life-saving treatment and personal insurance of rescue personnel should keep up. Only in this way can it be adapted to the characteristics of chemical leakage accidents to rescue poison, flammable and explosive.

Second, how to adapt to the characteristics of the leakage of leaks in chemical dangerous goods accident rescue

"Leakage" is a basic feature of a chemical accident. The main causes of leakage are operational errors, equipment failures, and design deficiencies. According to the statistics of many years of chemical accident investigations, leakages occurred in pressure vessels, valves, and pipelines that were out of service, and several large chemical accidents at home and abroad also proved this. For example, the explosion accident of a large-scale liquefied gas tank in Xi'an is caused by the fatigue rupture of the fluid valve. The leakage of liquid chlorine in railway tank cars of Fushun City detergent factory has the following two major approaches.

The first is to quickly close the valve that communicates with the leak and prevent toxic substances from leaking along the corresponding pipe from the original leak. This is the quickest and most effective way to stop leaks. In order to achieve this leakage, "Kung Fu" is not in war but in peacetime. This requires the rescue personnel to carry out a careful and meticulous site survey of the source of the accident before the accident. From raw materials, production processes to finished products, the entire process can identify the occurrence of leakage at each key location and key location. Leakage control valves, and then develop a practical and feasible target emergency rescue plan. If you do not investigate, plan is not prepared, site investigation during the occurrence of a spill is not possible; at the same time, if gas is shrouded at the site and the order is disorderly, the technicians of the unit where the accident occurred may not be able to find out the rescue personnel.

The second is the use of special tools, equipment plugging. The so-called special plugging tools and equipment refer to special tools that implement temporary and rapid plugging based on the principles of pressure, fixation, adhesion, and plugging, such as: China's current use of injection molding machines and metals produced by Jiangxi Shangrao Connaught Group. Magnetic suction cups and inlet pressure plugging bags, in addition to the geometric characteristics of the leak and the size of the internal pressure, specializing in the production of flanges and pipe clips cork and so on. This of course has a scientific test and manufacturing problem. I think that the research and trial production of such special tools and equipment should be done by the rescue team and the unit where the source of the chemical disaster occurred, under the leadership of the city's rescue headquarters. If there are no such special tools or equipment, it is a special leak accident. It is difficult to complete the rescue mission.

Third, how to adapt to the characteristics of chemical dangerous goods spill accidents sudden strong, fast propagation of aerosol groups

Due to the general emphasis on the safety of chemical production, a number of rules and regulations have been formulated on the safety of chemical production, and some laws have been initially grasped. However, due to the many triggering factors of chemical leakage accidents, accidents have unexpected characteristics. First of all, it is characterized by abruptness in the accident site (site). For example: toxic chemicals in iron (public) road transport, whether it is in the town or in the countryside, the accident may occur at any time, and its specific location is very random. Secondly, the performance of the accident occurred suddenly.

Leaking chemical poisons, due to their low boiling point and high volatility, are gases that are at normal temperature and pressure. Therefore, high concentrations of toxic or highly toxic aerosols are formed quickly after leakage. In the event of wind, this aerosol group will quickly spread to the direction of the downwind, and its speed of propagation is determined by the local wind speed. According to related data, it was found that in the plain or small low-vegetation areas, the velocity of the head of the aerosol group is equal to twice the high wind speed of 2 meters away from the ground; similar to the forecast wind speed of the local meteorological station (about 10 meters from the ground) . In this way, we can get a formula for the relationship between wind speed, cloud cluster arrival time and propagation distance: time (seconds)=distance (meters)/wind speed (m/s) If calculated by the above formula: Weather forecast wind level 3 (about 5 When m/s), the toxic clouds spread to a distance of 100 meters downwind, it only takes about 200 seconds. This shows that the speed of propagation is fast.

In view of the above-mentioned characteristics of sudden strong and fast propagation, emergency rescue must be quick and fast. Strive to do the following: First, alert the police. That is, the 119 Dispatching Command Center must be constantly prepared and on duty 24 hours a day. At the same time, the watchman must be familiar with the police procedures. The second is quick delivery. That is, rescue commanders and rescue teams must be quickly called, quickly centralized, quickly acted, and quickly put into rescue operations. The third is that communication equipment should adapt to the requirements of rapid system. To achieve the combination of wired and wireless, fixed and mobile, fire-fighting green and local speech combination and join, listen to clear, uninterrupted requirements. Fourth, command and decision-making must adapt to the requirements of rapidity and rapidity. Achieve rescue decision-making computerization and automation. Fifth, the evacuation warning signals for the masses must be adapted to the requirements of rapidity and rapidity. Special rescue sirens should be deployed around the area to alert the threatened residents and clarify the direction of evacuation.

Fourth, how to adapt to the characteristics of the spread of toxic cloud clouds susceptible to meteorological and topographic conditions

1. The spread of toxic clouds is susceptible to meteorological effects

The meteorological conditions affecting the spread of toxic clouds are wind, precipitation, air temperature, and air vertical stability. The impact of the situation is similar to that of toxic clouds. According to the multiple tests conducted by the PLA's anti-chemical warfare force, its impact characteristics are as follows:

(1) Wind impact characteristics:

Wind factors include wind direction, wind direction stability, and wind speed. The joint action of the three determines the geographical scope and concentration of toxic clouds. The direction of the wind determines the direction of propagation of toxic clouds and the stability of the wind determines the spread of poisonous clouds. Without the influence of topographic features, the toxic cloud clusters spread downwind.

The wind speed determines the speed of the spread of toxic clouds. The wind speed is large, the propagation speed is fast, the propagation distance is long, and the geographical spread is large, but the concentration is reduced. If the wind speed is too high, the concentration in most areas will be reduced below the allowable concentration of toxicants, and the area of ​​hazardous areas will be relatively reduced. When there is no wind, poisonous clouds will spread around the leak, and the concentration in the area near the leak will be high, which may increase the poisoning concentration of poisoning personnel.

(2) Impact characteristics of precipitation: Precipitation includes rain and snow. Heavy rain will reduce the concentration of toxic clouds in the air to varying degrees, and some of the poisons dissolve or hydrolyze with rain. For example, ammonia and water soluble ammonia are synthesized and phosgene rapidly fails to meet water. However, the effect of light rain and snowfall on reducing the concentration is not obvious.

2. Poison cloud clusters are also vulnerable to topographic conditions

The terrain conditions affecting the spread of toxic clouds are mountainous, hilly and urban residents. According to information provided by the anti-chemical warfare unit of a unit, the following characteristics are: The characteristics of mountain hills: The terrain of hilly terrain is undulating, and the local micro-meteorological conditions in such cities are variable, and the impact of the spread of toxic clouds is more complex. For example, for more independent hills, poisonous clouds will generally pass from both sides of the mountain under the action of the system and will not reach the top of the mountain. It is quite safe to evacuate people to the top of the mountain during rescue. The mountains (hills) create a flow of toxic clouds and local concentrations may increase, but overall, the spread of poisoned air is accelerated, and the depth of propagation is greatly shortened. When the valley is in line with the system wind, or when the angle is not more than 30 degrees, toxic cloud clusters are formed. It will spread along the valleys and increase the depth of the propagation; poisonous clouds will remain in the valley for a long time when the valley is perpendicular to the system wind.

3. Impact characteristics of urban residents:

The influence of urban residents on the spread and spread of poisonous cloud clusters is also very complicated. The shape, direction, and width of the streets of urban residents are different. The level of buildings and their sizes affect wind direction and wind adjustment. When the toxic clouds flowed through the urban residents, they were partially overrun and some were stranded. During the convection, toxic cloud clusters can “climb” along the surface of the Yang surface, and it is safer upstairs when temperatures are reversed. The poisonous clouds can flow into underground buildings and spread along underground passages or pipelines during inversion. When there is wind, the direction of the street has a decisive influence on the direction of propagation of poisonous clouds. When the street is wide and the direction is the same as the wind direction, or the angle is not more than 30 degrees, the wind speed is between 4 and 8 meters per second. There is no obstruction in the streets; the angle between the wind direction and the street is 30 to 60 degrees, and the flow rate of poisonous clouds is slowing down; the angle between the wind direction and the street angle is 60 to 90 degrees. If the floor is not high, toxic clouds can cross the street. When the house is high, it may be blocked; toxic cloud clusters are easy to stay in dead lanes, alleyways, courtyards, and leeches. In short, the higher the wind speed is, the shorter the street buildings are, and the more toxic the clouds are.

According to the above characteristics of toxic clouds that are vulnerable to meteorological and topographic conditions, how can emergency rescue work adapt? First, the commanding and rescue teams must strengthen the study and study of meteorological knowledge, especially micro-meteorological knowledge, and master their influence characteristics and laws. Second, the 119 command center should regard the collection of weather data as an important task; Detailed micro-meteorological surveys should be carried out on the areas surrounding the sources of accidental disasters, especially in cities located in mountainous areas. This work should be regarded as an important part of on-site investigation of emergency rescues, so as to provide accurate data for the rapid decision-making system of microcomputers.