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Optimizing Exhaust Air Purification in Painting and Drying Processes
TECHNOLOGY
spotlight
Optimizing Exhaust Air Purification in Painting and Drying Processes
T
he process of painting and drying car bodies produces gaseous pollutants that have to be removed from the air depending on the paint system and statutory requirements. Innovative recuperative incinerators are ideally suited for cleaning exhaust air flows from dryers because the heat energy contained in the clean gas can be re-used in the drying process. Recuperative oxidizers, such as Dürr System’s Ecopure TAR line, can be used for cleaning exhaust air from paint spray booths. The painting process produces particularly large exhaust air volume flows that have only low pollutant loads. For this reason, a system for concentrating the solvent-laden exhaust air flows— namely the Ecopure KPR concentrator line—can be installed between the paint spray booth and the exhaust air purification system. How it works: the exhaust air volume flow is reduced significantly for the subsequent thermal exhaust air purification process. The resulting increase in the pollutant concentration significantly decreases gas consumption because the energy contained in the pollutants makes a contribution during oxidation. As in all thermal processes, the exhaust air is heated in the Ecopure TAR enough to oxidize the hydrocarbons to produce mainly water vapor and carbon dioxide. The polluted air is first preheated by the hot air in the integrated (recuperative) heat exchanger. This allows a large portion of the combustion heat to be recovered. When the air enters the combustion chamber, the burner heats it further and initiates oxidation of the pollutants, which is comwww.metalfinishing.com
pleted after they have passed through the chamber. With the Ecopure TAR, special emphasis must be given to Dürr’s controllable POWERFLEX heat exchanger. The outlet temperature of the purified exhaust air can be controlled independently of the combustion chamber temperature. Due to the variable operating point of the
Dürr's Ecopure TAR thermal air purification system effectively cleans exhaust air from paint booths and dryers.
oxidizer, the outlet temperature of the TAR can, for example, be reduced to save energy–without having a negative effect on the clean air quality. In short,the Ecopure TAR saves significant fuel energy and operating costs, achieves better emission levels, and produces a longer system service life thanks to lower combustion chamber temperatures. Complementary systems. An increasing number of automotive paint shops are working with Dürr’s innovative dry separation system EcoDryScrubber, which binds excess
paint particles in dry filters—i.e. without water contact. This system not only reduces the energy consumption of the paint shop by up to 30%, but also offers advantages in exhaust air purification. The reason for this is that exhaust air from the EcoDryScrubber is highly concentrated and efficiently filtered. This permits a very compact design for the Ecopure KPR VOC concentration system and the connected TAR recuperative oxidizer, which are used for exhaust air purification. (Dürr optimized the Ecopure KPR so that it can be ideally combined with the EcoDryScrubber paint spray booths.) Furthermore, the exhaust air purification systems can be operated very economically. The reason is that they require very little energy because the pollutants themselves supply sufficient fuel energy for operation. For Dürr customers, this means lower investment costs and around 80% less energy consumption. A good example of the EcoDryScrubber system at work is a new Dürr installation in Ningbo, China, for SVW Shanghai—the joint venture between the Volkswagen Group and the Chinese SAIC Group. According to Dürr engineers, the system saves 60% energy in the spray booth by means of up to 95% air recirculation. This air recirculation contributes significantly to a painting process that is nearly independent of the outside climate, thus contributing to a consistently high application quality. The EcoDryScrubber needs no water or detackifier chemicals, and no paint sludge is produced that requires costly disposal.
ABOUT DURR SYSTEMS Dürr is a mechanical and plant engineering group that holds leading positions in the world market in its areas of operation. It generates a good 80% of its sales in business with the automotive industry. It also supplies the aircraft, machinery, chemical, and pharmaceutical industries with innovative production and environmental technology. For more information, please visit www.durr.com or e-mail Marta Kelly at [email protected]. September 2012 I metalfinishing I 29
spotlight
Optimizing Exhaust Air Purification in Painting and Drying Processes
T
he process of painting and drying car bodies produces gaseous pollutants that have to be removed from the air depending on the paint system and statutory requirements. Innovative recuperative incinerators are ideally suited for cleaning exhaust air flows from dryers because the heat energy contained in the clean gas can be re-used in the drying process. Recuperative oxidizers, such as Dürr System’s Ecopure TAR line, can be used for cleaning exhaust air from paint spray booths. The painting process produces particularly large exhaust air volume flows that have only low pollutant loads. For this reason, a system for concentrating the solvent-laden exhaust air flows— namely the Ecopure KPR concentrator line—can be installed between the paint spray booth and the exhaust air purification system. How it works: the exhaust air volume flow is reduced significantly for the subsequent thermal exhaust air purification process. The resulting increase in the pollutant concentration significantly decreases gas consumption because the energy contained in the pollutants makes a contribution during oxidation. As in all thermal processes, the exhaust air is heated in the Ecopure TAR enough to oxidize the hydrocarbons to produce mainly water vapor and carbon dioxide. The polluted air is first preheated by the hot air in the integrated (recuperative) heat exchanger. This allows a large portion of the combustion heat to be recovered. When the air enters the combustion chamber, the burner heats it further and initiates oxidation of the pollutants, which is comwww.metalfinishing.com
pleted after they have passed through the chamber. With the Ecopure TAR, special emphasis must be given to Dürr’s controllable POWERFLEX heat exchanger. The outlet temperature of the purified exhaust air can be controlled independently of the combustion chamber temperature. Due to the variable operating point of the
Dürr's Ecopure TAR thermal air purification system effectively cleans exhaust air from paint booths and dryers.
oxidizer, the outlet temperature of the TAR can, for example, be reduced to save energy–without having a negative effect on the clean air quality. In short,the Ecopure TAR saves significant fuel energy and operating costs, achieves better emission levels, and produces a longer system service life thanks to lower combustion chamber temperatures. Complementary systems. An increasing number of automotive paint shops are working with Dürr’s innovative dry separation system EcoDryScrubber, which binds excess
paint particles in dry filters—i.e. without water contact. This system not only reduces the energy consumption of the paint shop by up to 30%, but also offers advantages in exhaust air purification. The reason for this is that exhaust air from the EcoDryScrubber is highly concentrated and efficiently filtered. This permits a very compact design for the Ecopure KPR VOC concentration system and the connected TAR recuperative oxidizer, which are used for exhaust air purification. (Dürr optimized the Ecopure KPR so that it can be ideally combined with the EcoDryScrubber paint spray booths.) Furthermore, the exhaust air purification systems can be operated very economically. The reason is that they require very little energy because the pollutants themselves supply sufficient fuel energy for operation. For Dürr customers, this means lower investment costs and around 80% less energy consumption. A good example of the EcoDryScrubber system at work is a new Dürr installation in Ningbo, China, for SVW Shanghai—the joint venture between the Volkswagen Group and the Chinese SAIC Group. According to Dürr engineers, the system saves 60% energy in the spray booth by means of up to 95% air recirculation. This air recirculation contributes significantly to a painting process that is nearly independent of the outside climate, thus contributing to a consistently high application quality. The EcoDryScrubber needs no water or detackifier chemicals, and no paint sludge is produced that requires costly disposal.
ABOUT DURR SYSTEMS Dürr is a mechanical and plant engineering group that holds leading positions in the world market in its areas of operation. It generates a good 80% of its sales in business with the automotive industry. It also supplies the aircraft, machinery, chemical, and pharmaceutical industries with innovative production and environmental technology. For more information, please visit www.durr.com or e-mail Marta Kelly at [email protected]. September 2012 I metalfinishing I 29