Fire and explosion accidents often occur in chemical plants, causing serious damage to enterprise production and society. Some fire and explosion accidents occur repeatedly. For example, Water shortage caused boiler explosion accident, gas jacket and drum suffocation explosion accident, transforming saturated hot water tower explosion accident, synthetic tower internals damage and ammonia tank explosion accident, etc.
Reasons for chemical plant fire and explosion are as below:
1.Leakage of combustible gas.
A.Gas leakage from dynamic and static seals of equipment
B.Gas leakage from Equipment Corrosion Pipeline
C.No water in water seal and gas leakage occurs
D.Gas leakage due to defect or rupture of valve in equipment pipeline
Such accidents are mainly caused by improper management of production equipment, poor material quality or maintenance of sealing materials, improper operation and maintenance, no pressure relief but add additional force during maintenance, not operate according to procedures regulations for starting and stopping of inspection, etc.
It must be managed in accordance with the relevant regulations such as the stipulated overhaul operation rules, the standards of leak-free factories and the regulations on power management of equipment. To detect and eliminate leaks in time, preventive measures should be taken to avoid enlargement or disaster accidents.
2.System at negative pressure, air and combustible gas mixing
A.When the system stops, negative pressure and inhalation of air will occur as the temperature drops after stopping.
B.The system is shut down and water cut off. After shutdown, the water seal loses its function due to leakage, resulting in air inhalation.
C.Operation error, improper connections, incomplete or failure of alarm interlocking devices, resulting in unbalanced gas pumping causes negative pressure, air suction occurs from the open or leakage.
D.The gas inlet pipeline is blocked by debris, crystals or water, causing negative suction and inhaling air from an open or leaky place.
E.When air is used for pressure test and leak test, the combustibles in the system are not cleaned up and no blind plate is added, resulting in the mixture of combustible gas and air.
Most of these accidents occur in gas transmission or gas compression related positions. When they occur in the process of pressurization, they are more dangerous, because in explosive mixtures, on the one hand, the oxygen content is increasing, on the other hand, after pressurization, the explosion limit range is enlarged, and accidents are more likely to occur.
3.Oxygen content exceeding standard rate in system production
Oxygen content exceeding the standard rate may occur in many parts, but the reasons are mainly concentrated in the gas-making positions, which are usually caused by operational errors, equipment defects, personnel violations, oil breakage, steam breakage or failure of safety alarm devices. Oxygen content exceeding the standard rate may occur in areas such as desulfurization, transformation and compression, which should be paid special attention to.
A.High-pressure gas blows to low-pressure gas, forming over pressure explosion
B.Chemical explosion caused by mixture of air and combustible gas
The former is mostly due to operational errors and failure of low-voltage safety accessories or accessories. For example, the explosion of synthetic high-pressure series and low-pressure liquid ammonia tank, the explosion of synthetic high-pressure series and low-pressure regeneration system, etc. The latter is mostly due to the error of blind plate plugging, which is caused by valve replacing blind plate or miss-operation. If a device is on fire, there is air inside. Because the system is not isolated by blind plate, the flammable gas leaks into the valve or someone’s misoperation to the closed valve, which causes the flammable gas to enter the equipment under fire and mix with the air to form explosive mixture gas, thus explosion occurs.
5.Fire work not in accordance with rules
A.Private fire work without fire certificate and fire safety knowledge
B.Although the application for fire certificate is get, but not completely replaced or the sampling method is incorrect, the analysis result is wrong.
C.Poor consideration of fire safety measures
D.Safety conditions of the scene for fire work is not carefully checked
E.Fire system is not completely isolated from other systems
F.Self change of safety measures or time of fire operation certificate
G.Non-replacement or non-maintenance positive pressure ignition
Such accidents are the most of chemical fire and explosion accidents. As the fire operation is highly technical and requires high management, the safety and technology departments should effectively control it in order to prevent accidents.
Preventive Measures for Fire and Explosion Accidents
Control and Eliminate Risk Factors
1.One is reasonable design. In the process of design change, advanced technology and high-level, reliable fire and explosion protection measures should be adopted, and safe technological specification and reasonable piping should be adopted.
2.Another is correct operation and strict control of process indicators. The technical regulations for safety production in chemical enterprises are the summary of the experience of safety production for many years. As long as we strictly follow the regulations, strictly control the process indicators, exceed the limits of the indicators within the scope prescribed by the regulations, and take effective measures to reverse them immediately, instead of reluctantly maintaining them, the anticipated safety results can be achieved.