Emergency Rescue of Leakage Accidents in Liquefied Petroleum Gas Tankers

Liquefied petroleum gas tankers play a very important role in transporting liquefied petroleum gas. In recent years, due to lack of special transportation channels, accidents involving liquefied petroleum gas (LPG) automobile tank cars that occur in highways or densely populated areas have become commonplace, resulting in the leakage or burning of large quantities of liquefied petroleum gas, which seriously threatens the lives of national property and the people. Rescue and rescue of such problems should be valued by all parties.

First, the characteristics of the accident

Accident characteristics

The sudden characteristics of accidents involving liquefied petroleum gas vehicle tankers, especially accidents caused by night-time driver fatigue, will increase the difficulty of rescue. Once the tank leaks due to a traffic accident, the liquefied petroleum gas quickly volatilizes and diffuses and mixes with air to form an explosive mixture. A gas explosion (belonging to an explosion) may occur at any time in the event of Mars. The high-temperature flame after explosion can cause the temperature of the tank to rise sharply, and the pressure in the tank increases accordingly. When it exceeds the tolerance limit of the tank, the tank explosion (which belongs to the second explosion) will occur, and the explosion of the tank can be far more powerful. Exceeding gas explosions, the high temperatures, shock waves and explosion debris it generates will cause great harm to the personnel on the ground. At the same time, a large number of liquefied petroleum gasses in the tank are released instantaneously, again causing gas explosions (belonging to three explosions), forming a more destructive three-dimensional explosive region with a combustion propagation speed of 2km/s to 3km/s.

2. The parts of the tank that are prone to accidents

Safety accessories (level gauge, manhole cover, safety valve, emergency shut-off valve, etc.) leak or burn; the tank itself is severely deformed or partially torn, resulting in leakage or burning of large quantities of LPG; cab severely deformed or ignites and burns. Seriously endanger the adjacent liquefied petroleum gas tanks.

Second, start the rescue plan

1. Alarm self-help

After a traffic accident occurs, drivers, escorts, or on-site people who still have warning capabilities should immediately dial 119 and 120 to report the location of the accident vehicle to the fire, medical care, quality supervision, safety supervision, and local people's government where the accident occurred. , Tank medium type, media quality, damage caused on the spot and the future development trend of the accident, etc., and take measures to self-rescue, rescue the wounded, determine the cause of the accident and possible The hazards caused are to prevent the further expansion of the accident, to strictly protect the scene of the accident, and to properly preserve all kinds of physical evidence such as site-related objects and important traces.

2. Establish rescue command organization

The people's government in the place where the accident occurred should urgently initiate a corresponding emergency contingency plan for hazardous chemicals and special equipment; if the local city can not effectively control the accident hazard, it is recommended to start the provincial plan; if the accident is particularly serious, the provincial-level rescue also cannot effectively control the accident hazard. It should be recommended to start state-level emergency rescue. After the person in charge of the accident emergency command center arrives at the scene of the accident, he will further understand the prior disposition, and based on the accident situation and the need for emergency response, if necessary, an on-site command center will be set up to study and formulate and implement various emergency treatment plans. According to actual needs, the on-site command headquarters may establish several working groups to be responsible for rescue and rescue, medical treatment, hygiene and epidemic prevention, public security precautions, traffic control, emergency communications, personnel evacuation and resettlement, social mobilization, news reports, material security, and life support. Wait for work. The on-site rescue team can be composed of quality supervision, safety supervision, public security, and fire protection departments, organize professional rescue and on-site rescue forces, carry out on-site disposals, and dispatch follow-up treatment and reinforcement teams at any time according to the on-site rescue situation, quickly forming the following 3 group.

Personnel Rescue Team: Composed of the public security, armed police, civil air defense, and medical departments, responsible for the rescue of the wounded at the scene of the accident. Fire-fighting and explosion-proof team: The fire department is responsible for the fire prevention and spray cooling at the site of the accident. Hidden Trouble Disposal Team: Composed of accompanied personnel and professional emergency rescue teams, they are responsible for identifying the nature, type, impact scope, and other existing hazards of the accident, and under the guidance of technical experts, elimination and disposal may cause secondary hazards. The hidden danger.

3. Relief supplies and equipment transfer

Fire-fighting equipment and equipment: fire engines, fire hoses, fire hoses, various types of dry powder, and carbon dioxide fire extinguishers. Protective equipment: air respirator, anti-static anti-static overalls, protective insulation clothing, fire shelters, anti-freeze lined rubber gloves, a variety of gas masks. Plugging equipment and supplies: cranes, dry powder, combustible gas concentration tester, wind direction meter, pressure plugging fixtures with different specifications, clamps, pressure tools, high-pressure injection guns, manual high-pressure pump, fire protection professional construction tools, explosion-proof Flashlight, sealant suitable for liquefied petroleum gas medium. Medical treatment equipment: medical ambulances, commonly used rescue equipment and medicines.

Third, implement emergency rescue

1. Initial assessment of accident hazards

Rescue teams and technical expert teams shall conduct initial assessments of the scope of the accident, the potential for accidental hazard propagation, casualties, and property losses, and provide first-hand information for the on-site rescue headquarters.

2. Demarcate the alert area

Establish an on-site emergency rescue work area, and establish on-site rescue work areas based on the type of accident, scale and degree of damage, weather conditions (especially wind direction, temperature) and other factors. It is strictly forbidden that all unrelated personnel, vehicles and articles enter the work area, and at the same time open up safe passage for emergency rescue personnel, vehicles, and goods and materials, and maintain public security and traffic order at the scene of the accident. The on-site emergency rescue work area is divided into three parts: the danger zone, the buffer zone, and the security zone.

For emergency rescue, it is the explosion danger area and damage area that are important. Within the explosion danger zone, all fire sources must be banned to prevent deflagration of gas. In addition to rescue personnel equipped with protective equipment, other rescue personnel should be placed outside the injury zone. In actual emergency rescue, it is generally a demarcation zone that includes explosion hazard areas and damage areas and considers the safety factor. The combustible gas concentration tester can be used to measure the gas concentration in various directions around the leak site. The concentration range is greater than 2% within the warning zone. Due to the fact that the density of gaseous liquefied petroleum gas is greater than air, the tester should be located close to the surface. Since the gas diffusion is influenced by the conditions of leakage, wind force and other conditions, the alert range must be adjusted at any time according to the measured value.

In the warning area, all fire sources must be eliminated. The ignition energy of liquefied petroleum gas is only 0.2-0.3mJ. Commonly used telephones, radios and other communications equipment, cameras, cameras and other publicity equipment, flashlights and other lighting equipment, fire-fighting vehicles, wrenches and other rescue equipment are potential The source of fire, these devices can not enter the warning zone. The tools used to enter the vigilance zone must be non-sparking tools and the electrical appliances must be explosion-proof. The paraffin can be coated on the surface of ordinary iron tools to prevent sparks. The exposed metal parts such as the hose interface are taped to prevent sparks from colliding with the concrete floor or other metal when the hose is dragged. During a rescue operation, collisions between metals may generate sparks. Use the water gun to aim the water at the collision site to prevent sparks.

3. Emergency evacuation and rescue personnel

In the case of leakage of liquefied petroleum gas tanks is very serious, and short-term risks are difficult to be effective, the evacuation area surrounding the residents and the masses shall be immediately divided, the evacuation instructions shall be issued, the personnel shall be evacuated and cleared, and the evacuation shall be conducted. Medical, health protection and relief work in the process. During the evacuation, the wind direction was upward, and the wind was evacuated and transferred to rescue the injured.

4. Determine the parking position and attack direction according to the gas diffusion

The liquefied petroleum gas has a certain law of volatilization and diffusion. Liquefied petroleum gas liquids quickly evaporate into gas, which is 1.5 to 2 times as dense as air. The gas diffuses along the ground and accumulates on the surface and in low-lying areas. It is difficult to diffuse and the gas concentration gradually decreases from the center of the leak. The concentration of gas in the near area is higher than the upper limit of the explosion concentration, which is the high concentration area. The gas concentration in the far area is within the explosion concentration range, which is the explosion danger area. The gas concentration in the periphery is lower than the lower limit of the explosion concentration, which is the low concentration area. If Mars is present in the explosion-hazardous area or high-concentration area, the gas in the explosion-risk area will explode, and the gas in the high-concentration area will burn quickly. During this short period of time, the gas temperature in high-concentration and explosion-risk areas soars and the volume expands instantaneously. The hazard scope is larger than the original high-concentration area and explosion danger area. Personnel will be harmed in this area; outside the injury area is Safe place. The diffusion of gas is affected by the amount of leakage, and if the amount of leakage is large, the diffusion range is large.

The gas diffusion will also be affected by the wind and the terrain. If there is wind or uneven terrain at the scene of the leakage accident, the diffusion speed of the gas in the direction of the lower wind direction and the lower direction of the ground is obviously faster than that of other directions, forming an irregularly shaped high-concentration area, explosion danger area and damage area.

Fire engines should stop at the point of leakage, crosswind, high ground, and far from the leak. The front is outward so that the fire truck stops quickly when the wind direction changes. When the engine belt of a fire truck is rotating at a high speed, an electrostatic voltage of a kilovolt is generated and its discharge energy is enough to ignite the liquefied gas. Many of the car's electrical equipment are not explosion-proof electrical appliances. Therefore, fire engines must be parked outside the explosion danger zone.

Rescue and rescue should choose to approach the leak from the upper direction of the leak and the higher direction of the ground. In this direction, the radius of the explosion danger zone and the damage zone is small, and the radius of the explosion danger zone and damage zone is large in the downwind direction and in the lower direction of the terrain. Therefore, it is easier to approach the leakage point for reconnaissance and blocking from the windward direction and the high terrain. leak.

5. Logistical guarantee of plugging

Ensuring reliable water supply is critical to the success of plugging. Dispersing liquefied petroleum gas (LPG) and protecting the plugging personnel require a lot of flushing water. Once the water supply is interrupted, the safety of the leakage and rescue personnel will lose their protection. A 10t liquefied petroleum gas tanker requires nearly 1,000 tons of water for emergency rescue. Therefore, it is necessary to pay attention to liaising with the water supply department and notify the water supply department if necessary to pressurize the fire water pipeline at the scene of the accident to ensure sufficient water supply.

6. Safety protection against plugging

Plugging personnel should wear positive-pressure self-contained breathing apparatus, wear anti-static insulation clothing, wear anti-frost protection products when handling liquid liquefied petroleum gas leakage, and prohibit the use of non-explosion-proof electrical appliances and tools; on-site operators must have fire-fighting water The screen serves as a cover. When the flame volume increases rapidly due to the diffusion of gas, the noise of the fire (especially the burning tank) increases continuously, the combustion flame changes from red to white, the light shines, a harsh whistle blows from the combustion, and the jar shakes. When the color of the tank changes, an undamaged safety valve sounds indicating that the tank is about to explode. At this point, the plugging operation should be stopped immediately, all rescue personnel should be evacuated to a safe location, and dangerous areas, buffer areas and safety areas should be re-delineated.

In view of the actual harm caused by the accident to the human body, animals, plants, soil, water, and air, and possible harms, measures such as closure, isolation, and cleaning are promptly taken to prevent the continued harm to people and the pollution to the environment. The hazards caused by accidents are monitored and processed until they meet the national environmental protection standards.

Liquefied gas tanker vehicle use units, safety supervision and management departments, and drivers and escorts must be responsible for their own duties, strictly perform their work functions, strictly implement work procedures, ensure the quality of work, and minimize the probability of tanker traffic accidents.