热化学法处置退役风电叶片污染物生成特性

Pollutants generation characteristics from retired wind turbine blades treated with thermochemical methods

  • 摘要: 风电叶片由于重量轻、强度大、叶片长等特点,一直是固废行业回收处置的难点。热化学法处置退役风电叶片是一项较为有潜力规模化工业推广的技术。针对热化学法处置过程中的污染物排放问题,在管式电炉实验台上对风电叶片样品分别在N2、CO2和空气气氛下进行了400、600、800、1000 ℃四个不同温度下的热转化实验,测试了含氮、含氯污染物排放情况。发现CO2和氮气气氛下,HCN和NO是主要的含氮污染物,随着温度增加,HCN逐渐增加,在1000 ℃时,HCN形态氮是最主要的含氮组分,占总氮比例达到88.3%,而HCl形态氯占总氯比例波动不大,维持在5%上下波动。空气气氛下,NO是最主要的含氮污染物,峰值体积分数达918.3×10−6,并且,生成的NO中的氧主要来自风电叶片自身,而非外部空气。随着温度增加,HCl和HCN逐渐减小,在400 ℃达到最大,占总氯、总氮比例分别为46%、8.4%。CO2对产物的分布有显著的促进作用,这种促进作用与温度、组分相关。1000 ℃高温下CO2能显著促进HCN和NO的生成,但是在400 ℃低温下,促进作用并不明显。在400 ℃低温下,CO2对NO2的生成有显著的促进作用,1000 ℃高温下,CO2对生成NO2促进作用不明显。考虑到生成NO的氧主要来自叶片自身,传统的空气分级对降低氮氧化物并不明显,中试开发需要专门配套烟气除氮、除氯装置。

     

    Abstract: Due to the light weight, high strength, and long blades of wind turbine blades characteristics, it has been a difficult problem for the recycling in the solid waste industry. The thermochemical treatment of retired wind turbine blades is a technology with great potential for large-scale industrial application. In response to the issue of pollutant emissions during the thermochemical treatment process, the pre-treated wind turbine blades thermal conversion experiments were conducted on a tubular electric furnace experimental platform under four different temperatures of 400, 600, 800, and 1000 ℃ during N2, CO2, and air atmospheres, respectively. The pollutants emissions containing nitrogen and chlorine were tested. Under the CO2 and N2 ambience, HCN and NO are the main nitrogen-containing pollutants. As the temperature increases, HCN gradually increases. At 1000 ℃, HCN-N is the most important nitrogen-containing component, accounting for 88.3% of total nitrogen. However, the proportion of HCl-Cl to total chlorine fluctuates little, maintaining around 5%. Under the air ambience, NO is the main nitrogen-containing pollutant, with a peak concentration of 918.3 × 10−6. Moreover, the oxygen in the NO mainly comes from the wind turbine blades themselves, rather than the external air. As the temperature increases, HCl and HCN gradually decrease, reaching their maximum at 400 ℃, accounting for 46% and 8.4% of total chlorine and total nitrogen, respectively. CO2 has a significant promoting effect on the distribution of products, which is related to temperature and composition. CO2 can significantly promote the generation of HCN and NO at a high temperature of 1000 ℃, but the promotion effect is not significant at a low temperature of 400 ℃. At a low temperature of 400 ℃, CO2 has a significant promoting effect on the generation of NO2, while at a high temperature of 1000 ℃, CO2 has no significant promoting effect on the generation of NO2. Considering that the oxygen generated by NO mainly comes from the blades themselves, traditional air classification is not effective in reducing nitrogen oxides. Therefore, pilot development requires specialized flue gas nitrogen and chlorine removal devices.

     

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