Reliably purifying solvent-laden exhaust air from painting and coating processes is the core function of regenerative thermal oxidation systems. Most of these systems are heated using fossil fuels (mainly natural gas). Previous electric models were limited to low volumetric flows. Dürr CTS has found a way around this. The company is extending its Oxi.X range – the product line for thermal exhaust air purification systems – by electrifying all RTO designs.
Tried-and-tested multi-chamber technology with a new energy source
For the electric design, Dürr CTS is retaining the tried-and-tested multi-chamber systems and replacing the gas-powered burner systems with electric heating elements. The basic principle of the thermal process therefore remains the same: minimizing volatile organic compounds (VOC), hazardous air pollutants (HAPs), and odors in the process air through oxidation, in accordance with legal requirements. The result: the same purification performance, no open flames, and therefore no thermal NOₓ and no operational CO₂ emissions from the operation of the exhaust air purification system.
“We have installed more than 5,000 RTO systems worldwide in the past 30 years, including 600 electric versions of the Oxi.X RV flameless, single-bed exhaust gas purification system. With the changes in the political environment since 2022 and the resulting increase in the costs of primary energy sources, we have taken the next big evolutionary step by becoming the first provider to offer all our RTO designs in an electrified version,” says Carsten Walddörfer, Manager Product Management at Dürr CTS.
The right system for every process step
The requirements along industrial production processes vary significantly: volumetric flows and pollutant concentrations in the paint booth are high during surface coating of bodies but drop significantly during the subsequent drying step. The extended RTO range permits the targeted handling of exhaust air flows with different characteristics using the optimal system solution for each application. The tried-and-tested Oxi.X RV remains the right solution for low initial loads, while other series are designed for medium to high throughputs and pollutant requirements such as corrosion, condensation, or dust. In this way, each section of a production line can be designed with the best technology for optimum economy.
Ceramic heating elements for corrosive exhaust gases
Up to now, electric RTOs have reached their design limits when dealing with corrosive exhaust gases, as metallic heating elements wear out quickly when exposed to aggressive media, such as those found in processes involving halogen compounds. To counteract this, Dürr CTS provides the option of equipping the electric variant with ceramic heating elements. Ceramic materials can withstand even highly corrosive exhaust materials over the long term, ensuring reliable production under challenging conditions.
Independence from gas and flexibility in energy sources
With this expansion of its product range, Dürr CTS is responding to growing demand that is primarily driven in the automotive industry by two objectives: lowering CO₂ emissions and facilitating independence from gas supplies. Electric RTOs meet both these requirements at the same time, provided the electricity used comes from renewable sources.
In addition, companies can benefit from dynamic electricity rates, especially when combined with their own solar panels and battery storage. For existing systems, Dürr CTS offers electrically heated retrofit solutions. Newly installed systems can also be designed to retain the option of switching between gas- and electricity-powered operation in the future – an option that will gain in importance should CO₂ prices continue to rise.
