The molecular formula of dichloromethane is CH2Cl2. Colorless transparent liquid with sexual smell. It is slightly soluble in water, soluble in ethanol and. It is a nonflammable solvent with low boiling point. It is often used to replace flammable petroleum ether, etc.
It can be used as defoamer of polycarbonate, defoamer of film and film, and can be used as solvent of defoamer and defoamer of polycarbonate, film and film. Dichloromethane, a colorless liquid, is used as a reaction medium in the pharmaceutical industry for the preparation of ampicillin, benzylpenicillin and cephalosporin. It is also used as solvent, oil dewaxing solvent, aerosol propellant, organic synthesis extractant, polyurethane and other foaming agents and metal cleaning agents in film production.
Dichloromethane is mainly used in film production and medicine in China. Among them, 50% of the total production is used for film production, 20% for medical noodles, 20% for cleaning agent and chemical industry, and 10% for others. Dichloromethane is also used as a carrier refrigerant in industrial refrigeration system, but it is very harmful. It can produce highly toxic when contacting with open fire or hot objects. When wet air can hydrolyze to produce trace hydrogen chloride, light can also promote hydrolysis and strengthen the corrosion of metal.
Emergency measures for dichloromethane
Dichloromethane in the use process needs to be careful, because of its risk characteristics, if leakage occurs in the use process, corresponding emergency measures should be taken according to the detailed situation. What are the detailed measures?
1. Cut off the fire. 2. Cut off the leakage source as much as possible to avoid flowing into sewer, flood discharge ditch and other sexual space. 3. Quickly evacuate the personnel from the leakage contaminated area to the safe area, and strictly enter and exit. 4. It is suggested that emergency disposal personnel should wear self-contained positive pressure respirator and anti-virus clothing. 5. Small amount of leakage: adsorption or absorption with sand or other incombustible data. 6, a large number of leaks: build a dike or dig a hole to retain, cover with foam, reduce steam disaster; transfer the pump to the tank car or special collector, recover or transport to the disposal place of waste disposal.
Dichloromethane and open fire or hot objects contact can produce highly toxic, when wet air can be hydrolyzed to produce a trace of hydrogen chloride, released and hydrogen chloride are toxic, so in the process of use, be careful and careful.
Recovery method of dichloromethane tail gas
Due to its low boiling point and volatile nature, dichloromethane will be distributed to the air in the process of being pumped out by vacuum pump, which will cause damage to human body and pollute the environment. Is there a better way to recover the tail gas containing dichloromethane?
1. Absorption method
The absorption method is to contact the tail gas with the absorbent, or spray or counter current in the absorption tower. The absorption liquid includes diesel oil, DOP and other high boiling point solvents, or water added with cosolvent and coagulant. The absorption method is suitable for the management of medium and high concentration (above 2G / m3) and medium and small exhaust air volume (below 104m3 / h), and has low management efficiency for low concentration and large air volume waste gas. There are some problems in the absorption method, such as the post disposal of absorption solution, secondary pollution and secondary management.
2. Condensation method
Condensation method is to use dichloromethane at different temperatures of saturated vapor pressure is different, through cooling method to condense gas recovery. It has the advantages of simple equipment and easy operation. It is only suitable for high concentration gas. Condensation method is usually used only as a pre-treatment method.
3. Synthesis method
From the application situation, the single method is more suitable for the gas with small amount of gas and high concentration of pollutants. However, there are two main problems in the purification and management process of single method for dichloromethane waste gas with large gas volume and low concentration produced by many domestic processes: first, the problems of energy consumption and high operation cost of purification equipment operation are more prominent under this condition, and the cost and cost are higher; second, the waste gas generated by many domestic processes is high Some processes have the problems of low efficiency and secondary pollution, and the disposal effect is not satisfactory, which affects the large-scale implementation and application of the process. At present, in pharmaceutical production, two or more single methods are used for the recovery of methane tail gas.
4. Adsorption method
Adsorption method is to use activated carbon to adsorb and purify dichloromethane tail gas, especially for low concentration tail gas. The adsorption of this method is better, and the water vapor after adsorption is desorbed and condensed for recovery. High concentration (above 2G / m3) single component is suitable to be disposed by adsorption recovery method, while the multi-component and water-soluble solvents need to be further rectified after being disposed by this method. The tail gas treated by this method can reach the emission standard, which is of great significance to environmental management.
In general, when we recycle and dispose of dichloromethane tail gas, we should strengthen the recovery and development of the gas itself, do a good job in the overall treatment and application, so as to achieve the effect of strengthening the use.