石化污泥与煤流化床混烧污染物排放特性

Characteristics of pollutant emissions from co-combustion of petrochemical sludge with coal in fluidized bed

在一座热态循环流化床燃烧试验装置上对石化污泥与煤进行混烧试验,通过对焚烧过程中烟气成分进行分析,着重考察了质量掺混比、二次风率、过剩空气系数和床温对SO2、NOx和多环芳烃排放浓度的影响。试验结果表明,随着质量掺混比的增大,SO2和NOx的排放浓度下降,而多环芳烃排放浓度呈上升趋势。随着二次风率的增加,SO2的排放浓度上升,而NOx的排放浓度呈下降趋势。随着过剩空气系数的增加,SO2的排放浓度下降,NOx的排放浓度呈上升态势。随着床温或者过剩空气系数的增加,烟气中多环芳烃排放浓度均呈先下降后上升趋势。综合考虑稳定燃烧和降低污染物排放等因素,得出一系列最佳燃烧参数。燃烧温度应该控制在850～860℃,过剩空气系数应该控制在1.35左右,二次风率应该控制在40%左右,质量掺混比应该控制在30%左右。在本次试验范围内,各工况SO2、NOx和多环芳烃的排放浓度均满足国家排放标准。

The test of co-combustion of petrochemical sludge and coal was conducted in a circulating fluidized bed （CFB） test facility, focusing on the influences of mass mixing ratio, secondary air fraction, excess air coefficient and bed temperature on SO2 , NOx and polycyclic aromatic hydrocarbons （PAHs） emissions characteristics. The experimental results showed that when mass mixing ratio increased, SO2 and NOx concentrations decreased but PAHs emissions increased markedly. SO2 concentration in the flue gas increased but NO; concentration decreased with increasing secondary air fraction. As excess air coefficient increased, SO2 concentration decreased but NOx concentration tended to increase. PAHs concentration in the flue gas decreased at first and then increased with the increase in bed temperature or excess air coefficient. After taking those factors, such as stable combustion and reducing pollutant emissions into account, the following operation parameters are recommended ： combustion temperature between 850℃ and 860℃ , excess air coefficient of 1.35, secondary air fraction 40% and mass mixing ratio 30%. During the test runs, SO2, NOx and PAHs concentrations all met the national standard for pollutant emissions.