Oxy-fuel conversion of a TV glass tank and experience with noncatalytic denitrification

Abstract

The melting tank for TV funnel glass at SCHOTT GLAS was converted in 1996 from regenerative to oxy-fuel firing. The conversion was necessary to allow the required increase in tank size and pull. In connection with the conversion, the ΝΟx emission was to be reduced to less than 1000 mg/m3. Due to the special conditions regarding the oxy-fuel firing, the local authorities accepted an equivalent, mass-related ΝΟx emission limit. Furthermore, the authorities demanded the implementation of the SNCR denitrification process for further improvements. During the test period of the SNCR processing, problems with the stability of the temperature in the reaction zone and the homogenization between flue gas and ammonia appeared. The process was optimized. Additional purging air was used in the reaction zone, in order to control the temperature in the flue gas and in order to improve the mixing of the ammonia with the flue gas. The high load of condensate in the flue gas had a severe corrosion impact on the SNCR processing. Frequent maintenance is required for the ammonia insertion nozzles. The requested emission limit for ΝΟx could not be met without the application of the SNCR processing.