SO{sub x} emission control with the SO{sub x}-NO{sub x}-Rox Box

The SO{sub x}-NO{sub x}-Rox Box{trademark} or SNRB{trademark} pollution control system is an advanced emission control process for the removal of sulfur oxides (SO{sub x}), nitrogen oxides (NO{sub x}), and particulates (RO{sub x}) emitted from fossil fuel-fired boilers or processes. The key to this process is a high-temperature baghouse in which the combined reduction of SO{sub x}, NO{sub x}, and particulates takes place. A dry calcium- or sodium-based sorbent for SO{sub x} removal is injected upstream of the baghouse. Ammonia injection upstream of the baghouse is used to achieve NO{sub x} reduction on the surface of a selective catalytic reduction (SCR) catalyst, which is integrated in the baghouse. Advantages of the SNRB{trademark} system include: compact integration of the emission control technologies into a single component, dry sorbent and by-product handling, and improved SCR catalyst life due to lowered SO{sub x} and particulate levels. A schematic of the SNRB{trademark} process is shown. Injection of a dry sorbent and ammonia takes place upstream of a high-temperature baghouse. SO{sub x} is absorbed both in the flue gas duct and as the sorbent resides on the filter bags in the baghouse. A catalyst installed inside the filter bags provides for the selective catalytic reduction (SCR)more » of NO{sub x} as the flue gas and ammonia pass through the baghouse. Because the SO{sub x} and NO{sub x} removal processes can require operation at elevated gas temperatures (800{degrees}-900{degrees}F) for high removal efficiency, specially woven high-temperature fabric filter bags are used in the baghouse. The demonstration facility operation and testing began in May 1992 and was completed in May 1993. About 2200 hours of high-temperature operation were recorded on the demonstration facility. The project goals for SO{sub 2}, NO{sub x}, and particulate emissions are discussed. Each of the performance goals was met or exceeded in the demonstration program.« less