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I. Oxidation: The reaction between a substance and oxygen is oxidation (or the process of losing electrons is oxidation). Oxidation is widely used in chemical production. Since most substances that are oxidized in chemical production are flammable and explosive, and air or oxygen is often used for oxidation during the process, an explosive mixture may form in the reaction system at any time. Oxidation reactions require heating, and the reaction itself releases heat; if the proportions of the reactants are not correct or temperature control is inadequate, it can lead to an explosion in the system. Safety technical requirements during the oxidation process: 1. During oxidation, when air and oxygen are used as oxidants, the ratio of reactants must be controlled to stay outside the explosive range ； Before entering the reactor, the air should pass through a gas purification unit to remove dust, moisture, oil, and other contaminants, thereby reducing the risk of fires and explosions. 2. During the catalytic oxidation process, for exothermic reactions, it is necessary to strictly control the appropriate temperature and flow rate to prevent overheating and overpressure, and to avoid having the mixture within the explosive range. 3. Flame arresters should be installed on the pipes before and after the reactor to prevent the spread of flames, avoid fires, and ensure the safety of the system. 4. To prevent the reactor from exploding, a pressure relief device should be installed ； For process control parameters, automatic control, automatic adjustment, and alarm interlock devices should be used as much as possible. 5. The feeding speed must be strictly controlled to prevent overfeeding or incorrect feeding. 6. For oxidation reaction systems, nitrogen or steam fire extinguishing systems should be installed. II. Reduction: The reaction in which oxygen-containing substances lose oxygen is called reduction (or the process of gaining electrons is referred to as reduction). Reduction reactions are used in chemical manufacturing for purposes such as reducing nitro groups in nitrocompounds to amino groups, reducing nitroso groups, and reducing azo compounds and oxidized azo compounds. Some reduction reactions are relatively safe, but several are quite dangerous. For example, in catalytic hydrogenation reduction, due to the presence of hydrogen, if there are operational errors or defects in the equipment, hydrogen can leak into the working area and mix with air to form an explosive mixture that can explode upon contact with a flame source. Safety technical requirements during catalytic hydrogenation reduction: 1. During the operation, temperature, pressure, and flow rate must be strictly controlled. 2. Electrical equipment in workshop areas must meet explosion-proof requirements. 3. The ventilation in the workshop should be good; a lightweight roof should be used, along with skylights or vents, to allow hydrogen to escape promptly. 4. The hydrogen generated in the reaction can be led to the roof of the workshop through an exhaust pipe and discharged outside via a flame arrester. 5. Equipment for pressurized reactions must be equipped with safety valves or burst discs, as well as hydrogen detection and alarm systems. III. Nitration: The reaction in which a nitro group (—NO₂) is introduced into an organic compound molecule to replace a hydrogen atom, thereby forming a nitrocompound, is called nitration. The nitration process is an important reaction in the production of dyes and certain pharmaceuticals. The concentration of nitric acid and the reaction temperature have a significant impact on the nitration reaction. Moreover, the nitration reaction is a highly exothermic reaction; therefore, it must be carried out under cooled conditions. Most nitrocompounds are explosive, especially those with multiple nitro groups; they can explode when exposed to heat, friction, or impact. The vapors and dust of nitrocompounds are highly toxic; they can enter the body not only through the respiratory tract but also through the skin. In cases of severe poisoning in humans, loss of consciousness can occur, and death may even result. Safety technical requirements during nitration: 1. Strictly control the temperature of the nitration reaction and regulate the feeding rate; the addition of nitrating agents shall be controlled by double valves, and a backup cooling water supply system must be installed. 2. Continuous stirring is required during the reaction process to ensure uniform mixing of the materials ； It is also equipped with protective gas (nitrogen) stirring and auxiliary manual stirring facilities to prevent mechanical stirring from stopping due to a sudden power outage, which could lead to safety accidents. 3. Sulfuric acid is used as a lubricant for the mixing shaft, and as a heat conductor for the thermometer sleeve; ordinary machine oil and glycerin are prohibited from being used to prevent the formation of explosive substances upon the nitration of these substances. 4. The nitration tank should be equipped with an emergency discharge tank of sufficient capacity to allow for rapid discharge in the event of an accident ； The discharge valve is controlled by both a pneumatic automatic control valve and a manual valve. 5. The most dangerous abnormal phenomenon during the nitration process is the oxidation of organic substances; this phenomenon generates large amounts of brown vapor containing nitrogen oxides, while the temperature of the material rises sharply, which can cause the nitration mixture to be ejected from the equipment and lead to explosion accidents. Therefore, precise temperature control and continuous mixing of the materials are the key measures to prevent oxidation, which is why an automatic temperature control device must be installed. 6. The nitration equipment must be leak-proof to prevent the nitration materials from splashing onto high-temperature heat transfer surfaces such as steam pipes, which could lead to fires and explosions. When a pipe is blocked, it can be cleared by steam heating; it is strictly prohibited to use metal rods to strike it or to heat it with an open flame. 7. Open flames are strictly prohibited in workshop production areas, and electrical equipment must meet explosion-proof standards. IV. Chlorination: The process of replacing hydrogen atoms in organic compounds with chlorine atoms is called chlorination; this replacement is achieved by using a chlorinating agent to treat the material to be chlorinated directly. During the chlorination process, not only does the raw material react with the chlorinating agent, but the resulting chlorinated derivatives also continue to react with the chlorinating agent. As a result, in addition to monochloro substitutes, the reaction products also contain dichloro and trichloro substitutes; the chlorination products are thus a mixture of various chlorides. The chlorination reaction usually involves the generation of hydrogen chloride gas. Safety technical requirements for the chlorination process: 1. The danger associated with the chlorination reaction depends primarily on the properties of the substance being chlorinated and the conditions under which the reaction takes place; therefore, it is essential to strictly control all relevant process parameters. 2. Most of the raw materials used in this reaction are flammable and explosive substances; therefore, all ignition sources must be strictly controlled, and electrical equipment must meet fire and explosion prevention requirements. 3. The chlorination reaction is an exothermic reaction, and it becomes more intense in high-temperature environments ； Therefore, chlorination equipment must be equipped with an excellent cooling system to strictly control the chlorine flow rate, preventing safety accidents caused by excessive chlorine flow speeds and sudden temperature rises. 4. For the evaporation and vaporization device of liquid chlorine, a steam-water mixture is generally used to raise the temperature; the heating temperature shall not exceed 45°C, and the flow rate of the steam-water mixture is controlled by an automatic regulation device. 5. Chlorination reactions generally produce corrosive hydrogen chloride gas; therefore, production equipment must have corrosion-resistant properties and be leak-proof. 6. Hydrogen chloride gas must be collected and treated uniformly. 7. Rubber products are strictly prohibited as gaskets at connections of chlorination equipment and pipelines ； Lubricants that do not chemically react with chlorine must be used inside the equipment ； A check valve should be installed between the liquid chlorine cylinder and the chlorination equipment, along with a buffer tank of sufficient capacity to prevent backflow of the material.