What Is Liquefied Petroleum Gas?

Liquefied petroleum gas is a colorless volatile liquid obtained by natural gas or petroleum under pressure and temperature in a refinery. It is easy to ignite spontaneously. When its content in the air reaches a certain concentration range, it can explode when it encounters an open flame.

along with

LPG and

Is composed of hydrocarbons, the main components are propane, butane, and other alkane or olefins. The combined percentage of propane plus butane exceeds 60%, and below this ratio cannot be called liquefied petroleum gas. Each

Field of use

LPG refers to petroleum gas liquefied by high pressure or low temperature, referred to as "liquefied petroleum gas" or "liquefied gas". Its composition is propane,

There are usually three types of supply: bottled, pipelined and distribution tankers.

(1) Bottle supply

Liquefied petroleum gas is poured into steel cylinders and supplied to users. Liquefied petroleum gas cylinders are thin-walled pressure vessels with different specifications in different countries. The capacity of cylinders for household use is 10, 12, 15, 20 kg, etc .; the capacity of cylinders for public buildings and small industrial users is 45, 50 kg, etc.

(1) Explosive characteristics of liquefied petroleum gas

The first and biggest feature of LPG is the explosive nature of LPG. Explosions usually occur when LPG safety accidents occur, and they explode before burning. The main reason is that the heating value of LPG is relatively high. Comparing the heating value alone, the heating value of LPG is several times higher than that of ordinary coal gas, so it will occur when LPG has a safety accident. The situation of the explosion. After the explosion, combustion will occur. The combustion of liquefied petroleum gas is similar to the power of the explosion, and it is very destructive.

(2) Flammability of LPG

Liquefied petroleum gas has the main components of petroleum. These components include propane, butane, propylene, butene, etc. The components are typical hydrocarbon compounds, and they also have the biggest characteristic of hydrocarbon compounds is flammability. In addition, the flash point and spontaneous ignition point of these hydrocarbon compounds contained in the liquefied petroleum gas component are very low, and it is easy to cause combustion.

(3) Toxicity of LPG

Liquefied petroleum gas is a toxic gas, but there are certain conditions for this toxic volatility. Only when the concentration of liquefied petroleum gas in the air exceeds 10% will the body be toxic. When the human body is exposed to such toxicity, vomiting, nausea and even coma will occur, which will cause great harm to the human body.

(4) Flowability of LPG

Liquefied petroleum gas is very easy to flow, and once a leak occurs, the liquefied petroleum gas will flow out of the reservoir. In general, 1 liter of liquefied petroleum gas will volatilize into about 350 liters of gas after flowing out. These gases will burn when they encounter electricity, causing a serious fire ^[6]

1. Cause analysis of liquefied petroleum gas leakage

The essence of leak explosion is chemical explosion, which is combined with air after the leakage of liquefied petroleum gas to form an explosive mixture, which reaches the explosion limit and explodes when exposed to an open flame. The explosive power of liquefied petroleum gas is extremely great. The explosive power of 1 kg of liquefied petroleum gas is equivalent to the equivalent of 4 to 10 kg of TNT explosive. Liquefied petroleum gas fires and explosions are most commonly caused by leaks, and they occur most often.

The main reasons for the formation of liquefied petroleum gas leaks are as follows:

(1) Poor quality equipment for storing liquefied petroleum gas

The quality of the container that holds the liquefied petroleum gas is not good, such as improper equipment selection, defective design, and non-compliance during the manufacturing process, which may reduce the quality of the product or lack the necessary safety devices (level gauges, safety valves, Pressure gauge, vent tube, etc.), it will easily cause liquefied gas leakage.

(2) Failure of storage tank safety accessories

If the safety accessories (pressure gauge, level gauge, thermometer, safety valve, sewage pipe, etc.) of the LPG storage tank fail, it is easy to cause the tank to be overfilled or overpressured, causing the tank to crack and cause leakage; in addition, if it is safe The connection between the attachment and the tank body is not tight, the sealing flange of the valve flange is aging, the quality of the dry joint is poor, and the compressive strength is low, which will cause cracks, and it is easy to cause liquefied petroleum gas leakage.

(3) Human error

During the production, use and storage of liquefied petroleum gas, due to incorrect operation, illegal operation, blind command and poor equipment maintenance, it is easy to cause material runaway, dripping, dripping, and leaking accidents, and the pump is not tightly sealed during transportation. Switch, flange connection is not strict, unauthorized increase of the transmission pressure, rupture the pipeline, or the pipe connection is not strong.

2. Several Reasons for LPG Steam Explosion

A steam explosion is a physical explosion caused by the release of liquefied petroleum gas. When the liquefied gas is suddenly depressurized, the liquid in the storage tank is in a relatively superheated state. If the superheat is relatively large, it will cause the violent evaporation of the superheated liquid. Causes steam explosion. Its characteristic is that a phase change occurs during the explosion. It is an explosion caused by the rapid vaporization of the liquid phase. The explosion energy comes from the expansion of the boiling liquid and steam.

(1) Overfilling

Liquefied petroleum gas has the characteristics of thermal expansion. The specific gravity of liquefied petroleum gas decreases with increasing temperature, and its volume increases. The volume expansion rate of liquid is 10 to 16 times larger than that of water. Each time the temperature of liquefied petroleum gas rises, the volume expansion is about 0.3% to 0.4%, and the pressure increases by 0.02 to 0.03MPa. Because the liquid is actually incompressible, if the entire volume of the container is filled with petroleum gas, even if the temperature is not increased, it is easy to generate a large pressure due to the expansion of the liquid, causing the container to deform and explode. If it is subjected to flame baking, the temperature will increase to about 60 degrees, and the tank will be filled with liquid. The expansion force of the tank will directly affect the tank wall. After experimental measurement and theoretical calculation, the temperature of the full liquefied petroleum gas cylinder will rise by 1 ° C. The pressure inside the bottle increases by 10-20 atmospheres. When the safety design pressure of the storage tank is exceeded, it is easy to cause cracks in the weak part of the storage tank to cause leakage of liquefied gas. If the crack is too large, the pressure is released too quickly, or the liquid is overfilled or filled with liquid, the temperature will increase when it encounters sunlight or other conditions. When high, it causes a steam explosion. There are many steam explosion accidents caused by overfilling. The reason for an explosion accident of liquefied propylene tank truck in Spain was overfilling.

(2) High temperature baking

There is a danger of steam explosion in LPG storage tanks subjected to flame baking in the fire. The radiant heat of the flame around the container is introduced into the container, which causes the liquid in the container to boil to generate high pressure. Moreover, due to the container being exposed to fire, the tensile strength of the material of the container decreases sharply due to the high temperature, so that the container cannot withstand the set pressure and pressure of the safety valve When the safety valve set pressure is reached, the safety valve will burst open. In fact, the set pressure of the safety valve is relatively high. Even if the safety valve is opened quickly and exhausted, the container may crack due to the increase in pressure and then issue a steam explosion.

(3) Mechanical collision

The reason for the steam explosion caused by mechanical collision is that the container was damaged by the mechanical collision, and the pressure in the tank was instantly reduced, which caused the steam explosion. The danger of mechanical collision mainly comes from the derailment of the LPG tanker during transportation, the collision of the tanker during transportation, and the impact of surrounding objects (such as cranes) on the container.

(4) Equipment defects

If the equipment itself has defects (factory material factors, poor welding technology), it can cause large cracks in the container, and the leakage will cause a steam explosion. The thinning of the wall during use due to corrosion and other reasons will also reduce the strength of the container. Large cracks may occur and eventually lead to a steam explosion.

3. Preventive measures for LPG explosion

To prevent the occurrence of liquefied petroleum gas explosions, the pitch should be prevented from leaks by strengthening administrative management, optimizing processes and equipment, strictly operating, strengthening ordinary safety education and scientific emergency measures drills. Once a leak occurs, we must actively respond to it and take reasonable measures to scientifically and effectively stop the leak and prevent explosions. Don't deal blindly to prevent the accident from expanding. In the event of a leak or fire accident, the method of cooling with water should be adopted to cool the storage tank under flame grilling to avoid steam explosion, which will cause more serious consequences.

(1) Prevent leakage

First of all, storage equipment must be tight and leak-proof. To this end, it must be manufactured in accordance with regulations and qualified for technical inspection before it can be put into use. During use, it should be checked regularly to prevent leakage. The storage equipment shall be installed with necessary safety devices, and safe operating procedures shall be established and strictly implemented. Secondly, the selection of equipment materials must be appropriate and have good anti-corrosion performance; the sealing structure design should be reasonable, and the number of connected parts should be reduced as much as possible; Storage equipment should not be near heat sources, leak detection with naked flames is prohibited, and soap water can be used for leak detection. The storage place should be well ventilated, and the storage equipment should not be located in the basement. Shading and sun protection measures should be taken outdoors. Storage places are strictly forbidden in production operation to prevent operation errors, wrong operations, illegal operations; strengthen business training and professional use of open flame and non-explosive electrical equipment. Thirdly, strengthen safety education, increase responsibility and fire safety awareness, and reduce human-made accidents.

(2) Handling of leakage accidents

After a leakage accident, it is necessary to actively respond, and the accident unit may take certain evacuation and emergency measures. After the fire department arrives at the scene, it can take a warning zone. Immediately implement full martial law within a range of at least 800 meters from the leak point according to the terrain and weather. Draw a warning line, set up obvious signs, and notify people in the warning area and surrounding areas to evacuate quickly in various ways and means, and prohibit all vehicles and unrelated personnel from entering the warning area. Eliminate Tinders in the Guard Zone. Immediately cut off power and cease fire in the warning area, and extinguish all kinds of fire that may cause fires and explosions to prevent explosion accidents and cause greater harm. Before entering the dangerous area, spray the ground with a water gun to prevent friction and impact from generating sparks. The equipment should be grounded during operation. Spray dilution. Use a spray water gun to dilute the leaked steam, reduce the concentration of liquefied petroleum gas in the warning zone, and continuously detect the concentration of liquefied petroleum gas in the air with detection equipment to take scientific measures to prevent the leak.

Liquefied petroleum gas is a flammable and explosive dangerous substance. Fire and explosion accidents occur frequently during storage and transportation, causing serious consequences. Research on the types and causes of fire and explosion will help reduce the occurrence of similar accidents, understand some common precautionary measures, and help firefighters to take proactive and effective measures in a timely manner to minimize similar accidents Injuries caused by accidents, reducing losses ^[7]

(1) Fire prevention technology for storage

In the selection of LPG allocation address, you should choose the location at the edge of the city, and choose the open flame and the downwind direction and side direction of the spark. At the same time, a solid wall should be established around it. It is necessary to ensure that the solid wall reaches the specified height. There are distribution rooms, offices, duty rooms, etc., and storage areas, hydrocarbon pump rooms, compressor rooms, etc. are set up within the production. At the same time, corresponding equipment needs to be set up to work in strict accordance with safety technical requirements. Arrange independent compressor room, hydrocarbon pump room and other places, fire prevention distance also needs to reach the specified distance.

(2) Technical requirements for storage and pressure storage tanks

To ensure that oil storage tanks comply with relevant safety technical regulations, pressure gauges, flame arresters, safety valves, breathing valves, and other equipment need to be intact. Liquefied petroleum gas needs to be kept below the specified temperature. When there is no thermal insulation measures, cold water spray equipment is needed to achieve the main purpose of cooling.

(3) Storage tank processing technology

In the process of setting fire prevention and protection in the tank area, a water-sealed well should be set up, and a shut-off valve should be provided on the outlet pipeline. Some dangerous goods with low boiling points require liquids to be stored after the vapor pressure is completed, and then in accordance with the requirements for liquid operations, to prevent empty tanks from causing destructive effects when liquids enter.

(4) Technology of cylinder warehouse

Set up a special storage warehouse. The establishment of the warehouse needs to be established in accordance with specific requirements. There should be no underpass or trench in the warehouse. Tinder or heat sources are strictly prohibited. Ventilation equipment should be installed in the warehouse to keep the equipment dry and prevent direct sunlight from entering the gas cylinders. At the same time, the electromagnetic lifting mechanism should not be used. The bottleneck of the equipment should be screwed tight. At the same time, anti-vibration rings should be set on the gas cylinders. Do not collide or knock when entering the warehouse or during transportation.

(5) Gas cylinder processing technology

Cylinders and other more dangerous chemicals should be stored in accordance with the following storage regulations: the cylinders are neatly placed, and the caps are worn. In the process of standing, it needs to be fixed and leave a certain passage. In the process of horizontal laying, the head needs to maintain a consistent direction, and it also has strict requirements on the stack height. Under normal conditions, some special material gas cylinders need to be stored according to special regulations. The gas in some empty bottles that have been returned to the warehouse needs to maintain the residual pressure ^[6]

(1) Strengthening the safety management awareness of LPG use

Doing a good job in the safe use of liquefied petroleum gas needs to start from strengthening safety awareness, do a good job in education and practical activities for the safe use of liquefied petroleum gas, and always put safety awareness first. At the same time, the publicity and education of the safe use of liquefied petroleum gas needs to be done in normal work, so that people can conduct regular safety inspections of the liquefied petroleum gas storage equipment during the use of liquefied petroleum gas, and at the same time ensure that the liquefied petroleum gas is kept away from fire , And always in a ventilated place during use, to avoid the explosion caused by the leakage of liquefied petroleum gas.

(2) Strengthen the safety management of LPG equipment

During the use of liquefied petroleum gas, the safety management of enterprise equipment is very important. In the process of use, the enterprise needs to repair and adjust the equipment in question in a timely manner, and at the same time carry out the damage or aging equipment Regular updates. It also formulates detailed safety operating procedures for LPG equipment, strictly controls the safe use of the equipment, and performs strict leak detection on all sealed parts of LPG to ensure the safe use of LPG equipment.

(3) Adopting more advanced safety management technology methods

The technical method of safety management mainly refers to the corresponding management system. In all aspects of enterprise production, it is necessary to strengthen the supervision and management of the safety of the use of liquefied petroleum gas, and to implement real-time computer monitoring of key links on the basis of increasing capital investment to ensure that Deal with problems as soon as they are discovered to ensure the normal use of LPG.

(4) Do a good job of safety management for the use of LPG at the grassroots level

In the production process of the enterprise, it is necessary to do a good job in the safety management of LPG at the grassroots level. Because the LPG base unit is LPG safety ^[8]

Safe use

With the development of China's petroleum industry, many cities and towns have begun to use liquefied petroleum gas as fuel.

Although liquefied petroleum gas is easy to use, it also has hidden dangers. In case the pipeline leaks or the valve is not closed tightly, the liquefied petroleum gas will diffuse into the room. When the content reaches the explosion limit (1.5% ~ 9.5%), it will explode when it encounters Mars or electric spark. In order to remind people to find out whether the liquefied gas leaks in time, processing plants often mix a small amount of malodorous thiol or thioether compounds into the liquefied gas. This odor was immediately smelled as soon as the liquefied gas leaked. Take emergency measures.

1. Please pay attention to the inspection period of the cylinder, and attach the inspection standard.

Police inspecting LPG sales stores

2. Keep in a well-ventilated place away from direct sunlight.

3 Do not use the cylinder upside down.

4 Do not place objects on the cylinder to avoid ignition.

How to find out if the LPG pipeline is leaking?

When there is a suspected leak of liquefied petroleum gas pipes (pipes) in your home, you cannot use a match or a lighter to ignite the test. You should check for leaks with soap bubbles.

Where is the safest LPG water heater ?

It should be installed in a well-ventilated outdoor area to avoid accidents caused by carbon monoxide poisoning.

liquefied petroleum gas

What is the phenomenon of LPG pyrotechnics showing a red flame? What is the danger? What should I do?

The liquefied petroleum gas flame is normally light blue. If it is found to be red, it means incomplete combustion. There will be danger of carbon monoxide poisoning, so immediately ask a gas professional to repair and adjust the stove.

How did you know that LPG was leaking?

1. SmellLiquefied petroleum gas is mixed with odor, which will smell when leaked.

2. Vision-Leakage of liquefied petroleum gas will cause misty white smoke to form in the air.

3 Hearing-there will be a "hissing" sound.

4 Tactile-Your hand will feel cool when it comes to leaking holes.

What should I do if the liquefied petroleum gas leaks?

1. Close the LPG switch immediately.

2. Never turn any electrical switch on or off.

3 Gently open all doors and windows and quickly escape from the outdoors.

4 Call the police.

Will LPG kill people?

1. Liquefied petroleum gas itself is not toxic, but has anesthesia and asphyxiation, which reduces the biological response ability.

2. Improper use of liquefied petroleum gas will produce a large amount of carbon monoxide, which is easy to combine with hemoglobin in the blood, resulting in hypoxia (carbon monoxide poisoning and death)

What should I do if LPG is insufficient and carbon monoxide poisoning occurs?

1. Turn off the LPG switch.

2. Open doors and windows for ventilation.

3 Provide fresh air to the wounded.

4 Remove the restraint and open the airway.

5. If necessary, perform artificial respiration or cardiopulmonary pressure.

6. Do not turn on or off any power switch until the odor of LPG is gone, otherwise sparks may cause fire.

What are the symptoms of carbon monoxide poisoning?

1. Can cause headaches, dizziness, nausea, and vomiting.

2. It will have a strong sense of collapse, accelerated breathing and pulse, blurred consciousness, and the body cannot move autonomously.

3 Flushing, loss of consciousness, stop of breathing, and convulsions led to death of heartbeat.

What to do if the LPG pipeline is accidentally cut due to the construction of a sewage pipeline?

If the liquefied petroleum gas pipeline is accidentally excavated due to the construction of the sewage pipeline, the public is required to immediately shut down the source of fire at home. Smoking should be avoided, or steam, locomotive engines, and various power switches should be avoided to avoid explosion or combustion. Personnel should be as far away from the scene as possible. Before the handlers reach the scene, please surround the scene with a rope and write gas Leakage and other slogans to remind past people and vehicles.

LPG fire extinguishing method

Shut off the air supply. If the gas source cannot be cut off immediately, the burning gas is not allowed to be extinguished. Spray water to cool the container, if possible, move the container from the fire to an open area. Fire extinguishing agent: mist water, foam, carbon dioxide.

Emergency treatment of liquefied petroleum gas leakage

Quickly evacuate personnel from the leaked contaminated area to the upper reaches and isolate them to strictly restrict access. Cut off the fire. It is recommended that emergency handlers wear self-contained positive-pressure respirators and protective clothing. Do not touch the spill directly. Cut off the source of the leak as much as possible, and cover the sewers and other places near the leak point with industrial cover or absorbent / absorbent to prevent gas from entering. Reasonable ventilation to accelerate diffusion. Dilute with spray water. The leaking container should be properly handled, and used after repairing and inspection.

Precautions for storage and transportation of liquefied petroleum gas

Flammable compressed gas. Store in a cool, dry, well-ventilated warehouse. The temperature inside the warehouse should not exceed 30 ° C. Keep away from fire and heat sources, and avoid direct sunlight. Store it separately from oxygen, compressed air, halogen (fluorine, chlorine, bromine), oxidants, etc. The lighting, ventilation and other facilities in the storage room should be explosion-proof, and the switch should be located outside the warehouse. Fire storage and explosion-proof technical measures must be taken during tank storage. Prohibit the use of spark-prone machinery and tools. The tank truck should be filled with an appropriate amount when transported. Lightly load and unload during transportation to prevent damage to cylinders and accessories.