Analysis and Countermeasures of unsafe factors in

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Analysis of unsafe factors and accident prevention methods in the production of hydrogen peroxide by anthraquinone method

in recent years, China's hydrogen peroxide industry has developed rapidly, especially after the national "SARS" epidemic in 2003, the production capacity has doubled compared with the previous time, and the total domestic production capacity has reached 3million T/A. With the increase of the number of manufacturers and the continuous expansion of the scale of devices, the situation of safety production is not optimistic, and the requirements of safety production are becoming more and more strict. The unsafe factors and accident prevention methods in the production of oxygen accumulating water by anthrone method are analyzed and summarized as follows

I. The principle of producing hydrogen peroxide by anthraquinone method

a certain composition solution (called working solution) is prepared with 2-ethyl anthraquinone as the carrier and heavy aromatics and trioctyl phosphate as the mixed solvent. The working liquid is hydrogenated with hydrogen under the action of palladium catalyst in the hydrogenation tower to obtain the corresponding hydroanthraquinone solution, namely the hydrogenation liquid. The hydroanthraquinone in the hydrogenation liquid is oxidized with oxygen in the air under certain conditions. The hydrogenation liquid becomes the oxidation liquid, and the hydroanthraquinone is restored to the original anthraquinone, and hydrogen peroxide is produced at the same time. Oxidation should be comprehensively considered. The hydrogen peroxide in the capital liquid of the experimental machine is extracted by pure water countercurrent to obtain a product with a concentration of 27.5% or 35%, and then sent to the packaging process after purification. The working liquid extracted by pure water is purified by potassium carbonate and activated alumina in the separation, water removal and post-treatment processes, and then returned to the hydrogenation tower for recycling

II. Chemical properties of hydrogen peroxide

hydrogen peroxide is a strong oxidant, which is reductive when it meets a stronger oxidant. Its chemical properties are active. It can participate in decomposition, addition, substitution, and it can also replace the parts and components prepared by traditional metal materials and glass fiber reinforced materials. It can oxidize all organic compounds and a large number of inorganic compounds. Pure hydrogen peroxide is very stable at any concentration, but when it contacts with heavy metals, dust and alkaline substances and is heated, it can accelerate the decomposition, generate oxygen and water, and release a lot of heat to drive the nut to rotate. The decomposition speed is closely related to temperature, pH value, impurity content, etc., and its decomposition speed accelerates with the rise of the three

III. unsafe factors in the production process

according to the production method and material characteristics, combined with the specific operations in the production process, the following hazards exist in the process

1. The heavy aromatics, trioctyl phosphate, 2-ethyl anthraquinone and hydrogen used in the production of hydrogen peroxide by this method are combustible substances. Under normal circumstances, hydrogen peroxide and combustible substances are not allowed to be put together. Although the production operation is carried out under controllable conditions, there are objective unsafe factors in the actual production process. There are many varieties and large quantities of combustible and explosive substances involved in the production process

2. The hydrogenation of 2-ethyl anthraquinone in the working fluid is required to be carried out under weak alkaline conditions in the hydrogenation process, while the oxidation and extraction processes must be carried out under acidic conditions due to the existence of hydrogen peroxide. In the post-treatment process, potassium carbonate solution is also used to decompose the hydrogen peroxide and adsorbed water in the working solution. If it is not operated properly, the acid-base substances will be mixed with each other, and the pH imbalance of the system will cause the rapid decomposition of hydrogen peroxide, which will bring major potential accidents to production. It is this pair of contradictions in the production of hydrogen peroxide that brings certain difficulties to safe production

3. Under abnormal conditions, palladium catalyst and activated alumina used in production will mix hydrogen peroxide with impurities and decompose as the working solution enters the oxidation and extraction process

4. Hydrogen peroxide is a strong oxidant, which is very active. It is not only required that impurities should not be mixed in the production process, but also strict requirements for external conditions and container materials during storage, packaging and transportation

5. If a large amount of working fluid, aromatic hydrocarbon and hydrogen leak in the production process and mix with air (oxygen), it is easy to cause fire and explosion accidents when reaching the explosion limit

6. The oxidation reaction is an exothermic reaction, while hydrogen peroxide occurs when it meets heat. If the relevant parts are put into use and decomposed when they do not meet the requirements, if the reaction heat is not removed in time, the heat accumulation will raise the temperature in the oxidation tower. If it is not controlled properly, it is very easy to cause explosion and fire

7. When the flow rate of working fluid, heavy aromatics, trioctyl phosphate, hydrogen and other materials in the pipeline is too high or rapidly ejected, static electricity may be generated and fire may be caused

IV. accident prevention methods in the production process

in view of the unsafe factors analyzed above, in order to ensure safe production, the following aspects should be strictly done in the production process:

1 Strictly control the hydrogen peroxide content in the raffinate, the alkalinity of the circulating working liquid, the acidity of the oxidizing liquid, the alkalinity in hydrogen (for the synthetic ammonia and chlor alkali industries) and other important safety indicators. If the content exceeds the standard, the cause shall be found out immediately, and emergency shutdown shall be carried out when necessary

2. The decomposition of hydrogen peroxide is one of the main causes of fire and explosion accidents. Therefore, in the process of oxidation, extraction and purification, as well as the storage, packaging and transportation of products, it is necessary to strictly avoid the contact of hydrogen peroxide or materials containing hydrogen peroxide with alkali, heavy metals and catalytic impurities

3. Working fluid, aromatic vapor and hydrogen are easy to burn and explode under certain conditions, so it should be strictly avoided to mix with air (oxygen) and contact with open fire. When hot work is carried out in equipment or pipelines, the work can be carried out only after the replacement of inert gas is qualified

4. Do a good job in electrostatic grounding and lightning protection of equipment and pipelines, install flame arresters on vent pipes, and the electrostatic grounding resistance should be less than 5 Ω

5. Maintain the accuracy and normal use of key instruments of the system, such as the interface instruments of extraction tower and drying tower

6. In case of any abnormal phenomenon in production, it shall be handled in time, especially for the alkalinity in the oxidation tower and extraction tower, the violent decomposition of hydrogen peroxide, and the rapid rise of temperature, it shall be stopped immediately for treatment, the cause shall be found out, and the dangerous materials in the equipment shall be discharged quickly

7. Equipment and containers that contact or store hydrogen peroxide should have large enough exhaust ports to prevent fire and explosion accidents caused by overpressure explosion caused by equipment pressure holding

8. The materials of equipment, pipes, pipe fittings and other materials used in the production of hydrogen peroxide should meet the relevant standards, and should be cleaned and passivated to prevent heavy metal ions from entering the hydrogen peroxide water and causing decomposition

9. Put an end to the mixing of hydrogen peroxide or materials containing hydrogen peroxide with other substances that may cause the decomposition of hydrogen peroxide due to some reason (such as valve leakage, operation error), and disconnect the connected pipeline if necessary

10. Hydrogen peroxide should not contact with combustibles and reductants. Once hydrogen peroxide leaks or contacts combustibles, it should be washed and diluted with a large amount of water immediately

to sum up, there are many reasons for the accidents of hydrogen peroxide devices, most of which are accompanied by fire and explosion, and the decomposition of hydrogen peroxide is the main reason for the accidents. Therefore, during the production, storage, packaging and transportation of hydrogen peroxide, the decomposition of hydrogen peroxide should be strictly controlled, which is the main measure to prevent accidents. In addition, preventing the leakage of combustible substances such as hydrogen and working fluid is also an important means to prevent fire and explosion accidents

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