富氮生物质热解气的分级冷凝特性研究

采用固定床热解反应系统对稻壳负载尿素进行了热解耦合分级冷凝的研究,实验采用三级冷凝的方法,对比了热解温度(400、500、600℃)和冷凝温度(30、60、90℃)对产物分布和富集的影响,研究了生物质富氮热解和分级冷凝的机理。结果表明：富氮热解促进了Maillard反应产生含氮杂环物;分级冷凝富集规律明显,一级生物油富集了高露点的酚类,二级生物油富集了低露点的含氮杂环物;提高热解温度可以增加二级生物油中含氮杂环物的含量和降低二级生物油水分含量,热解温度为500℃时,液体产物产率和酚类产物产率最大;提高冷凝温度能增强各级油组分的富集效果,并降低一级生物油水分含量,一级冷凝温度为90℃时,水分几乎完全富集在第二级中,且一级生物油酚类产物含量最高。

Study on fractional condensation of pyrolysis vapors of nitrogen-enriched biomass

The pyrolysis coupling and grading of rice husk-loaded urea was studied by fixed bed pyrolysis reaction system. The experiment used three-stage condensation method to compare the pyrolysis temperature (400, 500, 600℃) and condensation. The mechanism of nitrogen-enriched biomass pyrolysis and fractional condensation was explored. The results showed that the Maillard reaction promoted the conversion of carbonyl compounds to nitrogenous heterocyclic compounds (NHCs) in the nitrogen-enriched pyrolysis process. The high value-added compounds were enriched by fractional condensation. Phenols with high dew points were enriched in first stage (Oil-1), while the second stage (Oil-2) enriched the low dew points NHCs. Liquid product yield, phenols content in Oil-1 and NHCs content in Oil-2 were increased with the pyrolysis temperature raised, especially the NHCs content reached highest (20%) in Oil-2 at 600℃. However, the liquid product yield and phenols content were decreased when the pyrolysis temperature was higher. As the first stage condensing temperature increased, the enrichment of phenols and NHCs were further improved, while the moisture content of Oil-1 was decreased. Particularly, when the first stage condensing temperature was 90℃, the water was almost condensed in the second stage (84%), and Oil-1 had the lowest water content 16%(mass)] and highest phenols content (43%).