6 November 25th morning, a workshop of methanol reaction kettle Xiyue Pharmaceutical Co. Ltd. Huayin exploded, killing 7 people injured, which killed 1 people, injured 1 people, injured 2 people, 3 people with minor scrapes.
After the accident, the main leaders of the municipal government of Huayin and the leaders of the municipal government went to the site to command the rescue and disposal work for the first time.
First, we quickly set up an accident rescue and rescue team organized by the deputy mayor of the municipal government as the leader. We quickly treated the wounded, organized the accident investigation, and did all the following good works.
Two is to arrange all pharmaceutical enterprises in the area to immediately stop production and rectify;
The three is to carry out a rapid safety inspection in the city, and to check and rectify all the hidden dangers of production safety.
At present, the treatment of the wounded, the investigation of the accident, the disposal of the aftermath and so on are in the orderly way.
Reactor explosion

Reactor is a batch reactor with stirred device. According to the pressure of different process requirements, chemical reaction can be carried out under open, closed, atmospheric pressure, pressurized or negative pressure conditions.
Reaction kettle is widely used in chemical, pharmaceutical, dyestuff, food and biochemical industries. It belongs to high temperature and high pressure equipment. It is highly dangerous and prone to material leakage and fire and explosion accidents.
In the process of production, the enterprise should focus on preventing all kinds of dangerous factors, using the reaction kettle correctly and doing well in the maintenance work.
Analysis of the cause of the explosion accident in the reactor
Improper operation and use, manufacturing and design defects, chemical corrosion and other factors are common causes of material leakage and fire and explosion accidents.
As the reaction kettle is usually toxic and hazardous chemicals, the result of the accident is more serious than the general explosion.
1. main manifestations of illegal operations
If the equipment is not replaced or replaced completely, the test car or the opening of the manhole is repaired. The air enters the tower to form an explosive mixture and explode. The number of explosion accidents is the most, especially in the production of small nitrogen fertilizer.
Use of flammable gas (such as the refining gas of the synthetic system, the transformation gas of the carbonization system) to fill, test and leak.
No hot analysis, hot processing (such as without blind will overhaul equipment and production system for isolation, poor quality or blind, or use asbestos for the blind), not for hot work permit is.
Bolts with pressure fastening valves and flanges.
Blind pursuit of production, overpressure and overload operation.
Unauthorized low storage tank level, so that the water seal does not work or because the post is not well coordinated, resulting in the compressor and pump negative, so that air into the human equipment to form explosive mixture.
Undergo the operation of equipment, did not discover the changes of process parameters within the device, resulting in explosion peroxide system.
2. main types of operation errors
When device replacement is cleaned, the order of replacement is wrong.
In the operation, the valve is staggered, or the switch valve is not in time, or the switch valve is in the wrong order, causing the equipment to hold back pressure or the overpressure of the gas flow back flow, causing the physical explosion.
Excessive feeding or unevenly feeding causes a sharp increase in temperature, or the solidification of the mother liquid in the equipment.
The condensation water is not discharged in time or improper operation, so that the operation of the equipment is overpressure with water.
The compressor and pump caused by the operation cause air into the equipment to form an explosive mixture.
Early stop pump stop water, resulting in the equipment overheating, melting, perforation.
The misplaced material can be heated and exploded in the recovery process.
Stagger the outlet valve of the oil tank, which leads to the overflowing of the roof and the explosion of the open fire.
3. the main performance of the poor maintenance
In the operation of the equipment, the leakage of combustible gas is caused by the leakage of the instrument nozzle and the tight seal of the valve.
The sediment was not cleared up in time, such as yellow phosphorus, brick mud and coke deposit, which made the pipeline blockage, causing the vacuum degree of the equipment to rise. The air entered the gas pipeline through the water seal, and the explosive mixture formed in the equipment, or the carbon deposition and spontaneous combustion exploded at high temperature.
The instrument device is out of order. Automatic emptying device damage, such as hydrogen damage, air enters the gasifier; when driving down the gas valve failure, resulting in the increase of oxygen content, even as high as 4.2%; vacuum condensation tank pipeline check valve on the failure, part of water into the tank caused by intense chemical reaction and explosion, copper liquid level meter burst and detonated.
The non condensable gas has not been discharged or exhausted, resulting in overpressure explosion.
Use epoxy as a preservative and apply it to the equipment to cause a fire.
Long term storage of equipment and high temperature lead to self polymerization or overloading of flammable liquefied gases. Heat and expansion of gases in storage and transportation at high temperatures cause explosion due to pressure rise.
The accumulation and runaway of oil vapor discharged from the source of oil vapor to the atmosphere, and the volatilization of residual products make the flammable and explosive system around the oil tank area. When the oil tank is agitated, the deposited oil and gas will evaporate and ignited when the slag is welded.
There are fire sources, mainly including welding fire, motor vehicle exhaust spark, static eliminator failure, electrostatic discharge, lightning fire and other ignition sources, such as iron collision, nail shoes and road friction generated by Mars.
4. the main defects of manufacturing are the following
The material of self-made or self-made refitting equipment does not meet the requirements and is not processed according to the relevant regulations and technical requirements.
The welding quality difference, such as welding equipment at the obvious and parent material and lack of fusion, continuous spot slag, porosity or small cracks and other phenomena, or the outer wall of one side welding and welding meat unbeveled, uneven thickness, weld metal pad bar.
The equipment is not machined strictly according to the drawings, and there is a hidden danger to the equipment accident. For example, the water jacket of the hydrolysis kettle of biphenyl is wrong and the water can not be eliminated in the lower part of the pipe, causing the boiling of the heat to cause the sudden explosion of the hydrolysate.
The old equipment or replacement equipment is not suitable for the valve and head because of its unclear material performance or its own defects, such as the old equipment, the installation position of the check valve is not correct, it can't prevent the flow of fluid from returning, or the atmospheric pressure equipment is pressurized.There was an explosion.
5. design defects
The technology is not mature, such as without material and heat balance, the small test data are blindly used in the large production equipment, so that the strength of the equipment is not enough and exploded.
In violation of the relevant provisions of pressure vessels, the square container is wrongly welded on the jacket, and the installation position is high, and it is exploded due to insufficient strength at high temperature and high pressure.
The equipment is designed at normal pressure, and the pressure exceeds the design pressure and explode because of insufficient strength.
6. the phenomena of chemical corrosion are shown as follows
The electrochemical corrosion and hydrogen corrosion are serious, making the local thickness of the equipment thinner or brittle.
The corrosion of the tower wall is serious and local perforation.
The corrosion caused the breakage of the equipment and parts, such as the broken of the central tube of the synthetic tower, and the high pressure oxygen corrosion caused the cracking of the tower to explode.
Leakage caused by corrosion of equipment.
Precautions for correct operation
When the reactor is used for production, the operator must standardize the operation. The error of the operation step will cause the damage of the reactor, affect the normal production order of the enterprise, and even cause the casualties.
1. operation by system
The enterprise should have a strict and standardized operation system of reaction kettle, and the operator should operate according to the system, which is the most basic requirement. Before the reaction kettle is operated, the operator should also understand the characteristics of the equipment and the related requirements.
2. pre operation check
The operation of the reactor, operation personnel must check whether the device is abnormal. When the equipment is running normally, the upper and the touch panels must not be opened to avoid electric shock.
No pressure operating equipment is strictly prohibited, which will not only damage the equipment, but also threaten the safety of the workers. In the process of nitrogen pressure test, we should pay attention to observing the change of the equipment so as to avoid the pressure too high.
Observation of 3. operation
When operating the reaction kettle, pay attention to the observation. Especially after the reaction kettle is heated to a certain temperature, the body can not contact the body of the kettle so as not to be scalded.
As most reactions are carried out under high temperature and high pressure, the raw materials and catalysts for reaction are mostly flammable and explosive materials, so the incidence of fire and explosion accidents is high. Fire and explosion protection measures should be implemented.
4. leak proof material leakage
The general process of risk &ldquo emissions and leakage control; ” a special process in danger of “ &rdquo, “ toxic substances; flammable and unstable substances, &ldquo number ” &rdquo, “ corrosion; leakage; — connecting head and padding & rdquo; etc. are in connection with the leak.
In the process of production, the enterprise should ensure that the equipment is reasonable and running well. Measures should be taken to reduce the leakage rate and reduce the risk of fire and poisoning.
5. control reaction temperature
There are usually agitators in the reaction kettle to ensure that the temperature in the reactor is uniform. Reactor temperature control at moderate cooling two (as internal is exothermic or endothermic). Heating is heated by steam, molten salt, or other heating medium, cooling water or other medium, and temperature is controlled by heating or cooling medium.
6. guard against the danger of explosion
When the instrument or device malfunction when the reactor material concentration in flammable range or near flammable range, &ldquo special technology risk; range close to flammable and flammable range of operating ” the risk coefficient will increase, should take measures to control the reaction mass explosion hazard.
The raw mixer should be placed near the inlet of the reactor to ensure that the raw material is mixed into the mixer immediately and enters the reactor.
When the oxidation reaction is carried out near the limit of explosion, the mixture ratio of raw gas to air or oxygen should be strictly controlled.
The production equipment should have automatic control instrument and safety chain alarm device. In addition, raw gas and oxygen or air can be used separately to avoid the formation of an explosive mixture.
7. configuration protection
There is a high risk of fire and explosion in the reactor, and more safety devices and fire protection facilities are used in the design.
In production, enterprises must pay attention to the integrity and investment rate of safety devices, otherwise the risk grade of the equipment will rise.
Not only should pay attention to the operation process of the equipment, but also pay attention to the maintenance of the equipment. After the fault is found, it should be repaired in time to keep the equipment in good condition.
During the operation of the reactor, the overtemperature and overpressure are prohibited, and the operating regulations should be strictly carried out.
Control the temperature of the jacket or the tube and the reactor according to the technological parameters.
Avoid temperature difference stress and internal pressure stress superposition to cause the equipment to produce strain.
Strictly control the proportioning ratio and prevent violent reaction.
It is necessary to pay attention to the abnormal vibration and sound of the reaction kettle. If a fault is found, it should be repaired immediately and the hidden danger is eliminated in time.
END
Source: Xi'an evening news, essential safety net