碳酸鉀和碳酸鈉負載於活性碳吸收煙道氣中二氧化碳 之研究：二氧化硫,氮氧化物,氧氣之影響

Abstract

本研究使用微分固定床反應器，探討於低溫潤濕條件下(60℃，70%RH)SO2、NOx、O2對於碳酸鉀和碳酸鈉負載於活性碳上吸收煙道氣中CO2之影響。在水氣、CO2、SO2、NOx和O2同時存在下，碳酸鉀反應生成碳酸氫鉀、偏重亞硫酸鉀、硫酸鉀、亞硝酸鉀和硝酸鉀；碳酸鈉則生成碳酸氫鈉、亞硫酸鈉、硫酸鈉、亞硝酸鈉和硝酸鈉。碳酸鉀/活性碳吸收劑同時與CO2(12.5%)、NOx(40-600ppm)反應，碳酸化轉化率隨NOx濃度上升而降低，但仍較單獨與CO2(12.5%)反應時為高；同時與CO2和SO2(50-1000ppm)反應，碳酸化轉化率隨SO2濃度上升而降低，但濃度低(≦200ppm)時碳酸化轉化率較單獨與CO2反應時為高。碳酸鈉/活性碳吸收劑同時與CO2和SO2或NOx反應，碳酸化轉化率隨SO2或NOx濃度上升而下降，但在低濃度(≦500ppmSO2或≦100ppmNOx)時，轉化率較單獨與CO2反應時為高。O2(2.5~5.0%)存在與否不影響碳酸鹽/活性碳吸收劑的碳酸化轉化率。一般燃燒廢氣中的SO2和NOx濃度若分別控制在200和300ppm以下，則碳酸鹽/活性碳吸收劑的碳酸化轉化率不低於廢氣中不含SO2和NOx時的轉化率。在相同反應條件下，碳酸鉀/活性碳吸收劑之碳酸化轉化率高於碳酸鈉/活性碳吸收劑。吸收劑可再生利用，其反應性劣化速率緩慢。

A differential fixed-bed reactor was employed to study the effects of SO2, NOx, and O2 on the absorption of CO2 from flue gas by K2CO3 and Na2CO3 supported on activated carbon under low temperature(60℃) and humid conditions(70%RH). With the presence of water vapor, CO2, SO2, NOx, and O2, K2CO3 was converted to KHCO3, K2S2O5, K2SO4, KNO2, and KNO3, and Na2CO3 was converted to NaHCO3, Na2SO3, Na2SO4, NaNO2, and NaNO3. When K2CO3-IAC reacted with CO2(12.5%) and NOx(40-600ppm), the extent of carbonation decreased with increasing NOx concentration, but it was greater than that for the sorbent which reacted with CO2(12.5%) alone.When K2CO3-IAC reacted with CO2 and SO2(50-1000ppm), the extent of carbonation decreased with increasing SO2 concentration, but when the SO2 concentration was low(≦200ppm), it was greater than that for the sorbent which reacted with CO2 alone. When Na2CO3-IAC reacted with CO2 and SO2 or NOx, the extent of carbonation decreased with increasing SO2 or NOx concentration, but at low concentration of SO2(≦500ppm) or NOx(≦100ppm), the extent of carbonation was greater than that for the sorbent which reacted with CO2 alone. The carbonation of sorbents was not affected by the presence of O2(2.5~5.0%). If the concentrations of SO2 and NOx in the flue gas were reduced to values below 200 and 300 ppm, respectively, the extent of carbonation of a sorbent would not be less than that when both SO2 and NOx were absent. Under the same reaction conditions, the extent of carbonation of K2CO3-IAC was greater than that of Na2CO3-IAC. The reactivities of the sorbents decreased only a little after regeneration.