The paint and printing ink manufacturer Marabu is currently modernizing its production facilities with a focus on sustainability, efficiency, and productivity. Part of this effort involves upgrading its air pollution control system. Many medium-sized paint and coating manufacturers in Europe, especially in Germany, installed emission treatment systems after the first German Technical Instructions on Air Quality Control (TA Luft) came into effect in the 1990s. These systems are now nearing the end of their service life. Based on the state of the art at the time, they were designed for the maximum expected pollutant load in the production exhaust air. Since then, even though paints and coatings are now manufactured with significantly lower solvent emissions, the systems have been continued running at full capacity, with correspondingly high energy consumption.
Marabu manufactures printing inks and liquid coatings for industrial applications. The expansion and modernization of its production facilities were expected to increase the volume of exhaust air by a quarter, to up to 20,000 standard m³ per hour. Marabu therefore opted for a new plant design from Dürr CTS that ensures compliance with emissions regulations, increases capacity, and significantly reduces energy costs.
The unique feature lies in the operating mode
The technical design of the new system is well established in the industry: concentration followed by recuperative thermal oxidation. The Sorpt.X CD rotary adsorber concentrates the solvents into a reduced flow rate, which is then fed into the Oxi.X TR recuperative thermal oxidizer. A downstream heat exchanger typically uses the process heat to preheat the small volume of desorption air. The unique feature of the new system lies in its operating mode. “We no longer generally operate at full load but instead adjust the thermal output to the actual pollutant load. To do this, sensors continuously measure the actual solvent concentration. This intelligent control system offers enormous potential for long-term energy and operating cost savings,” explains Ralf Brenner, Sales Manager at Dürr CTS.
Depending on the measured solvent concentration, the system switches between normal and optimized operation. Initial operating data confirm the concept. In January, due to low solvent emissions from paint and varnish production, the system operated in optimized mode approximately 81 percent of the time; this translates to a 51.6 percent reduction in gas consumption compared to static continuous operation. “The initial evaluations show that performance, cost-effectiveness, and environmental protection can be combined,” says Jürgen Schwarz, Plant Manager for Tamm and Bietigheim-Bissingen at Marabu. “We meet the emission requirements, have no odor nuisance, and our energy consumption has dropped significantly.”
Safety through process precision
Operating an air pollution control system with a concentration unit in a dynamic manner requires extensive process engineering expertise and experience in managing the time-delayed reactions of the adsorber and thermal oxidation. To ensure safe operation of the system under varying solvent concentrations, Dürr CTS analyzed the process, conducted a thorough risk assessment, and defined clear switching criteria that guarantee emission safety and explosion protection, even during load changes. Continuous LEL measurement monitors actual pollutant levels, while frequency-controlled fans regulate volume flows across operating modes. In normal operation, the system operates with a higher desorption air volume to ensure stable oxidation conditions, even under increasing load. At low solvent concentrations, the system switches to optimized operation with approximately 60 percent less desorption air. As a result, the thermal oxidation system heats a significantly smaller volume flow, reducing gas consumption accordingly.
For Marabu, the new exhaust air treatment system is a key component of its production modernization. It significantly reduces emissions and energy consumption and demonstrates that the modernization of an existing plant can be implemented in a way that makes both ecological and economic sense.
