The US Environmental Protection Agency recently revealed that in 2010, reductions in pollution attributed to the 1990 Clean Air Act prevented more than 160,000 premature deaths. The subject of emissions is highly topical in today’s industry; it is even more pronounced in ‘green’ industries such as solar, where there is an expectation that green energy must be generated by green processes. Rehm Thermal Systems is just one of the companies who have addressed this demand through its innovative approach to Thermal Oxidation. The company’s Thermal Oxidiser reduces emissions from the drying process during the metallization of crystalline solar cells to ensure emissions remain well below statutory limitations, in addition to lowering maintenance costs.
During the 200°C to 350°C curing process involved in PV metallization, significant quantities of vapour and smoke are produced. In order to avoid contamination and yield loss, these must be reliably exhausted from the process chamber. However, the challenge lies in the variation of available paste compositions, making it difficult for manufacturers to customise an effective filter or condenser to manage released vapour or smoke. The Rehm Thermal Oxidiser has changed this, using an advanced process to reduce emissions from solar dryers during solar cell metallization. With the Thermal Oxidizer, emissions remain well below the statutory limitations of pollutants, as reflected by TA-Luft, Germany’s Clean Air Act, for example. Since collection efficiency reaches 99.8%, the system significantly lowers maintenance costs for solar dryers and firing systems such as Rehm’s popular RDS dryer or RFS-D Fast-Firing system including Dryer.
Traditionally, condensate separators are used to meet the challenges of variable pastes and associated volatile constituents. However, with this method, collection efficiency is limited and mandatory disposal of accumulated condensates is expensive. Rehm’s Thermal Oxidizer delivers a more effective approach. Instigated by the heat of exhaust gas, the company’s thermal oxidation process uses these high temperatures to bind the volatile organic components and hydrocarbons from the metallization paste with oxygen, breaking them down into water vapour and carbon dioxide. By burning the long-chain molecules in the vapours/fumes, they become easily volatile substances that condense only with difficulty. These can then be easily removed from the system, drastically reducing the potential for condensation within the dryer. Since Rehm deploys only electrical heating systems, the company’s thermal oxidation process eliminates all potential for gas formation.
