为了揭示生物质锅炉中活性分子臭氧脱硝的特点,在一台应用了活性分子臭氧深度一体化超低排放技术的生物质循环流化床锅炉上,开展烟气臭氧脱硝试验。采用烟气分析仪测量锅炉尾部烟道活性分子臭氧喷入前和塔顶烟囱处的烟气组分,重点探究了脱硝前后烟气污染物的排放特性以及臭氧投加量对脱硝效果的影响。结果表明:由于入炉生物质燃料的水分和热值的变化有较强的随机性,机组负荷及CO、NOx等污染物初始浓度均随之波动;烟气中NOx初始浓度的平均值为146 mg/m3,最高值可达480 mg/m3,其瞬时值与含氧量有着非常强的线性相关性,线性回归相关系数(R 2)为0.96;随着臭氧投加量的增加,脱硝率从臭氧发生器功率为118 kW时的24%增至250 kW时的95%;应用活性分子臭氧脱硝技术后,臭氧发生器功率为250 kW时,烟气中NOx浓度一直稳定在15 mg/m3以下,满足超低排放标准要求。
关键词: 生物质锅炉, 循环流化床, 活性分子, 臭氧脱硝, 超低排放
In order to reveal the characteristics of reactive molecular ozone denitrification in biomass boilers, a flue gas ozone denitrification test was carried out on a biomass circulating fluidized bed (CFB) boiler using reactive molecular ozone ultra-low emission technology. A flue gas analyzer was used to measure the flue gas components at the positions before the injection of reactive molecular ozone and at the top of the chimney. The emission characteristics of flue gas pollutants before and after denitrification and the effect of ozone dosage on denitration were investigated. The results showed that the boiler load and the initial concentrations of pollutants such as CO and NOx fluctuated due to the strong random variation of moisture and calorific value of the biomass fuel. The averaged initial concentration of NOx in the flue gas was 146 mg/m3, while the highest value was 480 mg/m3. The instantaneous concentration of NOx had a very strong linear correlation with the oxygen content with the regression coefficient R2=0.96. With the increase of ozone dosage, the denitration efficiency increased from 24% at the ozone generator power level of 118 kW to 95% at 250 kW. After the application of reactive molecular ozone denitration technology, the NOx concentration in the flue gas stayed below 15 mg/m3 with the ozone generator power level of 250 kW, meeting the ultra-low emission standard.
Key words: biomass boiler, circulating fluidized bed, reactive molecular, ozone denitration, ultra-low emission