Investigation on low energy-consumed embedded selective catalytic reduction technology for pelletizing flue gas and the CO2 emission reduction assessment.

Abstract

Based on the unique technique property of grate-kiln pellet production process and its demand of ultra-low emission of NOx, a low energy-consumed embedded selective catalytic reduction (SCR) denitration technology was proposed. The temperature of the NOx-containing tributary flue gas was 350-500 °C, which basically accorded with the temperature range of SCR by V2O5-based catalyst. Considering thepotential inhibition effect of high SO2 concentration (8000-10000 mg/m3) and metal-containing dust in the pelletizing flue gas, the catalyst compositions were optimized to V2O5 (0.5%) and WO3 (5%), giving NO conversion over 90% with low yield of N2O by-product. Compared with the low-medium temperature SCR technology, it was no longer necessary to reheat the flue gas, showinga remarkable CO2 emission reduction effect. The CO2 emission reduction ratios were 94% and 66% contributed by the decrease of fuel and electricity consumption for the embedded SCR technology, respectively. The operating cost was also greatly reduced from 11.4 CNY/t-pellet to 3.1 CNY/t-pellet (Chinese Yuan).