Discussion on the treatment process of organic waste gas in chemical synthesis Pharmaceutical Project

[technical article of China Pharmaceutical network] the organic waste gas of the chemical synthesis pharmaceutical project will be generated in multiple nodes There are many kinds of pollutants, large amount of pollutants, and it is difficult to deal with toxic and harmful substances, causing damage to the surrounding environment According to the national VOCs control regulations, pharmaceutical enterprises should seriously carry out the treatment of organic waste gas A large amount of waste gas will be produced in the production process of chemical synthetic pharmaceutical projects The waste gas contains a large number of pollutants, and the amount of waste gas emissions is very large, causing great damage and pollution to the environment In this paper, the basic characteristics of organic waste gas generation in chemical synthesis pharmaceutical projects are explained in detail, and the commonly used organic waste gas treatment processes and process selection conditions are introduced in detail according to their characteristics, in order to bring effective help to the organic waste gas treatment in chemical synthesis projects 1 Characteristics of organic waste gas generation in chemical synthesis Pharmaceutical Project 1.1 production site: organic waste gas of chemical synthesis pharmaceutical project usually includes waste gas generated in feeding, reaction, centrifugal drying, refining, solvent condensation recovery, tank breathing, sewage treatment station and other links and locations 1.2 source of pollution The organic waste gas pollutants in the chemical synthesis pharmaceutical project usually include two aspects: on the one hand, they belong to the type of organic solvents The dissolving link of the reaction system and the separation and purification link of the chemical synthesis pharmaceutical project will be applied to many organic solvents, such as dichloromethane, dichloroethane, methanol, propanol, etc., among which some organic solvents are listed as "three causing substances" List Organic solvent is volatile and can produce organic gas On the other hand, it belongs to the pollutants formed during the reaction, specifically including raw materials, intermediate reaction products and final products, as well as some inorganic gases such as hydrogen fluoride, sulfur dioxide, hydrogen chloride, etc When mixed with inorganic components and organic waste gas, it can not be separated and discharged Therefore, the treatment of organic waste gas in chemical synthesis pharmaceutical project should be done well in the scientific disposal of inorganic gas first 2 The introduction of organic waste gas treatment process 2.1 The condensation process explains that condensation is a simple way to operate in waste gas recovery technology The main object of condensation process is the waste gas of organic solvent with high boiling point According to the technical policy for pollution prevention and control of pharmaceutical industry, the treatment of organic solvent waste gas should first adopt the condensation process, or the absorption condensation and ionic liquid absorption processes to achieve the recovery effect When the organic solvent waste gas cannot be recovered by the above methods, the combustion method should be tried A large number of solvents are usually recycled in chemical synthesis pharmaceutical projects A dedicated condensation recovery workshop is set up for waste gas treatment and recovery, and the condensation efficiency is greatly related to the amount of waste gas emissions In the process design, the first level cold water + the first level deep cooling (brine cooling or glycol solution cooling, etc.) is usually used In the condensation process design, the water-cooling temperature is required to be below 20 ℃, the deep cooling temperature must be - 5 ~ - 10 ℃, and the condensation time has fixed requirements According to the design specifications, the condensation recovery efficiency is significantly improved, and the condensation efficiency should generally be controlled at 95% ~ 98% This method usually can't reach the standard of emission, so it should be combined with other processes to do a good job in the rate of waste gas emission control 2.2 plasma technology Plasma technology is the production of plasma in the process of high-voltage discharge Plasma is formed by plasma After some electrons are deprived, atoms and clusters are ionized to form positive and negative ions to form ionized gaseous substances The working principle of plasma for pollutant removal is that high-energy electrons, free radicals and pollutants in exhaust gas react to oxidize and decompose organic molecules to form carbon dioxide and water, showing the effect of pollutant degradation During the application of plasma technology, attention should be paid to: the decomposition efficiency of some organic substances is relatively low, especially ring substances, which can only be broken down; secondly, corrosive acid gas will be generated during the decomposition of halogenated hydrocarbon; thirdly, there is a risk of explosion, so explosion-proof devices and preparations should be made In the process of operation, once the operation is improper or the management is negligent, there will be leakage of organic solvent and other materials, which is very easy to cause the concentration of organic gas to rise rapidly, to the lower explosion limit, and then to cause explosion Although the plasma device has concentration exceeding alarm and automatic power-off equipment, the design gas flow rate is faster than the alarm and cut-off time, so it can not fully play the role of safety protection 2.3 specific explanation of photocatalytic oxidation process the photocatalytic oxidation process is usually called UV photodegradation process, which belongs to oxidation technology The specific principle is to degrade the refractory organic matter in gas and liquid under high temperature and high pressure, and transform it into the easily degradable and water-soluble matter Therefore, this process can completely decompose and destroy the polymer organic gas, and decompose the small molecular organic matter into inorganic small molecular matter by means of decomposition and oxidation However, it can not completely oxidize the large molecule, ring molecule, long chain molecule, etc., only destroy the molecular structure, and can not completely improve the VOC problem It is usually used for deodorization, and can also be used for solution absorption The pretreatment of biodegradation process can improve the treatment efficiency 2.4 the combustion process is divided into direct combustion and catalytic combustion The high concentration organic waste gas can be directly combusted, and the heat can be recovered in the combustion process The medium concentration gas can only be combusted by catalysis When the concentration of organic gas is low, the adsorption + desorption process can be used to increase its concentration for catalytic combustion again The treatment method of organic solvent waste gas is stipulated in the technical policy for pollution prevention and control of pharmaceutical industry The recovery process should be adopted first, and the combustion process will be adopted if the effect of recovery process is not obvious However, in fact, the organic waste gas of pharmaceutical enterprises can not be directly treated by combustion process, because of the low concentration and small amount of organic waste gas In the process of high temperature incineration, nitrogen-containing pollutants are easy to produce dioxins, and the secondary pollution is difficult to deal with VOCs Pollution control technology policy contains VOCs exhaust gas Therefore, the treatment process for the waste gas containing halogenated hydrocarbon should be carefully selected Conclusion: the organic waste gas of the chemical synthesis pharmaceutical project will be produced in multiple nodes, with a large number of pollutants, a large amount of pollutants, and the treatment of toxic and harmful substances is difficult, causing damage to the surrounding environment According to the national VOCs control regulations, the treatment of organic waste gas should be carried out carefully Starting from the source control, improve the condensation recovery efficiency, reduce the production, carefully divide the types of waste gas pollutants, calculate the concentration and total amount of waste gas, and carry out scientific treatment based on this, so as to make the waste gas pollutants meet the emission standards after treatment Original title: Discussion on the organic waste gas treatment process of chemical synthesis pharmaceutical project Author: Chen Jifeng