Rehm CFR Counter Flow Reactor delivers high efficiency exhaust gas management with 99.9% VOC elimination and very low energy consumption
Advancing its award winning Thermal Oxidation System yet further forward, Rehm Thermal Systems VOC Counter Flow Reactor (CFR) is a high efficiency exhaust after treatment system for many processes where the exhaust gas is loaded with high solvent (VOC) concentrations.
The compositions of pastes used to metalize solar cells may vary greatly. This applies not only to the actual metal content (silver or aluminum powder), but to other additives as well, which are instrumental to the printing properties of the paste, as well as its drying and sintering characteristics. These materials may amount to as much as 25% by weight, where the greatest portion consists of the organic medium into which the solid materials are dispersed (powdered metal, metal oxides and inorganic binders, e.g. glass frit).
After being printed onto the solar cell at temperatures ranging from 130 to 300 ° C, the pastes are usually dried and baked/sintered into the solar cell during a second step at a temperature of greater than or equal to 800 ° C. Vapor/smoke forms while the pastes are being dried, which must be reliably exhausted from the drying system’s process chamber in order to avoid contamination of the system. The smoke consists of volatile constituents of the organic medium, which may be made up of various organic liquids that can additionally contain thickeners and stabilizers. Examples of organic liquids include alcohol (Texanol) and alcohol-ester (acetic acid and propionate), terpenes (pine oil, terpineol), resin solutions (methacrylate polymer), ethyl cellulose solutions in solvent (e.g. terpineol) and monobutyl ether from ethylene glycol monoacetate. Ethyl cellulose in terpineol, in combination with a thickener mixed with butyl carbitol acetate, is a preferred organic medium.
The Rehm CFR delivers VOC destruction rates as great as 99.9 %, with the exhaust gas heated to about 750 °C. At this temperature the molecular chains of the VOC`s are broken down to mainly CO2 and water vapor. The system employs an integrated heat recovery system so that both highly efficient emission control and at the same time very low overall energy consumption can be achieved. This gives lowest cost of ownership as well as compliance with the increasingly strict emission limits in legal environmental regulations.
Low COO has been a hallmark of Rehm, whose holistic approach to energy efficiency has resulted in new benchmarks for reduced power consumption and ambient atmosphere influence. For example, Rehm’s RFS Fast Firing system measures in at a typical 17KWh, and the RDS Drying system a meager 7KWh. In addition, external cover temperatures are maintained at <35 degrees C .
Elegant design concepts applied to the construction and operation of the Fast Firing process chamber include a metal-free multi-layer construction of ceramic insulation, and an advanced air distribution system. This heat exchange concept heats ambient gas (clean dry air) up to process temperature while the chamber insulation is simultaneously cooled down by the gas flow.