At the end of the current governance there are two main directions: First, recycling, and second, combustion treatment. In addition, there are a number of flexible packaging gravure enterprises using plasma technology to harmless treatment of exhaust gas. At present, some large-scale flexible package gravure printing enterprises in the industry have already started to recycle exhaust gas (solvent) for recycling, combustion or plasma harmless treatment, but for the national flexible package gravure printing industry, the proportion of enterprises adopting such practices is extremely small Currently less than 1%).
Recycling Law
Recycling mainly through physical methods, change the temperature, pressure, or the use of selective adsorbent and selective permeable membrane and other methods to collect and separate organic vapor phase pollutants, the main adsorption, absorption, condensation and membrane separation technology. The recovered volatile organic compounds can be directly or after simple purification and then returned to the process re-use to reduce the consumption of raw materials, or for the production of organic solvents with lower quality requirements, or for centralized separation and purification.
Dry composite process of a single organic solvent, high concentration of exhaust gas, the solvent recovery technology is now more mature. The flexible packaging gravure printing enterprise adopting the dry compound VOCs solvent recovery system has not only achieved good social benefits but also obtained obvious economic benefits. However, for the flexible packaging gravure process, although the organic solvent in the exhaust gas can be effectively recovered, due to the large investment in the recovery system, high operation and maintenance costs, insufficient purity of the recovered solvent, the ester solvent recovered by printing has sourness And other reasons, the economic benefits achieved are not obvious. In addition, the state has yet to issue a unified VOCs restriction policy for gravure printing. Most gravure printing enterprises do not actively deal with organic waste gas, but emit it directly or simply and discharge it at high altitude.
Regenerative catalytic combustion method
Regenerative catalytic combustion Exhaust gas treatment is to re-heat the organic waste gas discharged from the printing and compounding processes and decompose it into carbon dioxide and water vapor under the action of heavy metal catalysis, and then discharge it to the outdoors through an exhaust fan , The heat generated by combustion can be collected and used. At present, some domestic flexible packaging gravure printing enterprises use this technology to process organic waste gas and achieve good results.
Low temperature plasma technology
The principle of low-temperature plasma treatment of organic waste gas is: under the action of an applied electric field, a large amount of electron carrying electrons generated by the medium discharge bombard organic macromolecules to cause ionization, dissociation and excitation, and then trigger a series of complex physical and chemical reactions , So that the complex organic molecules of organic waste into harmless substances, so as to achieve the purpose of degradation.