Reactor safety hazards cannot be ignored
Reactors are intermittent reactors with stirring devices. Depending on the pressure required for the process, chemical reactions can be carried out under open, closed atmospheric, pressurised or negative pressure conditions.
The safety of the reactor and the production site environment are particularly important in the production and synthesis of chemical products. In recent years, reactor explosions caused by negligence have given the chemical industry a wake-up call. Seemingly safe materials can also cause safety accidents if they are not placed in the right quality.
Some of the safety hazards of reactors are as follows.
Feeding errors
If the cooling cannot be synchronised, the heat will build up and cause a local thermal decomposition of the material, resulting in a rapid reaction of the material and a large amount of hazardous gas explosion.
Pipe leakage
When feeding, for atmospheric reaction, if the emptying pipe is not opened, when pumping liquid material into the kettle, positive pressure will be formed in the kettle, which will cause the material pipe connection to break apart and the material to leak out causing personal injury and burn accident. When unloading, if the material in the kettle is not cooled to the required temperature (generally below 50°C), the higher temperature material will easily deteriorate and cause splashes and burns to the operator.
Heating up too fast
The material in the kettle is heated too fast, the cooling rate is low and the condensation effect is poor, all of which may cause the material to boil, forming a mixture of vapour and liquid phase, generating pressure and unloading the material from weak links such as the vent pipe, vapour phase pipe and the pressure discharge system such as the safety valve and rupture disc. If the material cannot be unloaded quickly enough, it may cause an explosion in the kettle.
Maintenance fires
If welding or gas cutting is carried out during the reaction of the material in the kettle without effective precautions, or if sparks are generated by tightening bolts or hitting iron, this may cause a fire and explosion if flammable and explosive materials are encountered.
Equipment construction
Reaction kettle design is unreasonable, equipment structure shape is not continuous, improper arrangement of welds, etc., may cause stress concentration; improper material selection, manufacturing vessel welding quality can not meet the requirements, as well as improper heat treatment, etc., may make the material toughness reduced; container shell by the erosion of corrosive media, strength reduction or lack of safety accessories, etc., may make the container in the use of the process of explosion.
Reaction out of control
Many chemical reactions, such as oxidation, chlorination, nitrification, polymerization, etc. are strong exothermic reactions, if the reaction is out of control or in case of sudden power or water failure, resulting in the accumulation of reaction heat, the temperature in the reactor rises sharply, the pressure increases, exceeding its pressure resistance, which will lead to the rupture of the vessel. Material from the rupture of the ejected, may cause fire and explosion accidents; reactor burst resulting in material vapour pressure of the equilibrium state is destroyed, unstable superheated liquid will cause 2 explosions (steam explosion); ejected material and then rapid diffusion, the space around the reactor is flammable liquid droplets or steam envelope, meet the ignition source will also occur 3 times the explosion (mixed gas explosion).
The main causes of uncontrolled reaction are: failure to remove the reaction heat in time, failure to disperse the reaction material evenly and operational errors.
Safety measures
Vessel inspection
Regular inspection of the vessels and reaction equipment, if found broken, must be replaced in time, otherwise, the consequences of unknowingly conducting experiments are unimaginable.
Pressure selection
Must be clear about the specific pressure required for the experiment, and choose a professional pressure gauge, within the pressure tolerance range for the test, otherwise, the pressure is small, can not meet the requirements of the experimental reactor, the pressure value is large, it is very likely to cause danger.
Experimental location
Physical and chemical reactions cannot be carried out casually, especially under high pressure, the requirements for the experimental site are even higher, so in the process of experimentation, the experimental site must be selected in accordance with the requirements of the test.
Cleaning
Pay attention to the cleanliness of the autoclave. After each experiment, it must be cleaned and never start an experiment without permission if there are impurities inside.
Thermometer
When operating, the thermometer must be placed in the reaction vessel in the correct way, otherwise, not only will the temperature measured be inaccurate, but the experiment may also fail.
Safety devices
Before the experiment, check carefully the various safety devices, especially the safety valves, so that the experiment can be carried out safely. In addition, these reactor safety devices should also be regularly checked, repaired and maintained.
Presses
High pressure reactors should use specific pressure gauges, usually the choice is a special pressure gauge for oxygen. If, by accident, a pressure gauge for another gas is chosen, there is a risk of unthinkable consequences.
Emergency measures in case of emergencies
1 Rapid rise in production temperature and pressure cannot be controlled
When the production temperature and pressure rise rapidly and cannot be controlled, close all the material import valves quickly; stop stirring immediately; close the steam (or hot water) heating valve quickly and open the cooling water (or chilled water) cooling valve; open the venting valve quickly; when there is no venting valve and the temperature and pressure still cannot be controlled, open the bottom discharge valve of the equipment quickly and discard the material; when the above treatment has no effect and the bottom discharge valve discard cannot be completed in a short time If the above treatment has no effect, and the bottom discharge valve can not be completed in a short time, quickly notify the personnel to evacuate the site.
2 Toxic and harmful substances leak in large quantities
Toxic and harmful substances in a large number of leaks to immediately notify the surrounding personnel to quickly evacuate the site upwind; quickly wear positive pressure respirator to close (or tighten) the toxic and harmful leak valve; in the inability to close the valve of toxic and harmful substances and then quickly notify the downwind (or around) units and personnel to scatter away or do a good job of prevention, and according to the characteristics of the substance spraying treatment agent for absorption, dilution and other processing. Finally, the spill will be stored and disposed of appropriately.
3 Flammable and explosive substances leak in large quantities
Flammable and explosive substances leak in large quantities to quickly wear positive pressure breathing apparatus to close (or tighten) flammable and explosive leak valve; in the inability to close the flammable and explosive leak valve and then quickly notify the surrounding (especially downwind) personnel to stop open fire, spark-prone production and operations, and quickly stop other production or operations around, while where possible, flammable and explosive leaks will be moved to a safe area to deal with. In the case of gas leaks that have burned do not rush to close the valve, watch to prevent backfires and explosions caused by gas concentrations reaching their explosive limits.
4 Identify the cause of poisoning immediately in the event of injury to personnel
In case of injury to personnel, immediately identify the cause of poisoning and deal with it effectively; in case of poisoning caused by inhalation, quickly move the poisoned person to the fresh air upwind. If the poisoning is serious, take the person to hospital quickly; if the poisoning is caused by ingestion, drink enough warm water to induce vomiting, or give milk or egg white to detoxify the person, or take other things to induce discharge; if the poisoning is caused by skin, remove the contaminated clothes immediately, rinse with plenty of flowing water and seek medical attention; when the person stops breathing, give artificial respiration quickly; when the person's heart stops beating, give artificial pressure to start the heart beating quickly; when the person When the skin of the body is burnt over a large area, immediately wash the burnt surface with a large amount of water, rinse for about fifteen minutes, while taking care not to get cold and frostbite, change uncontaminated clothing and then quickly send to hospital for medical attention.
Source: Reproduced
