脱水污泥与松木锯末共热解气化特性研究

发布时间：2018-05-16 17:02

  本文选题：污泥 + 生物质　； 参考：《华中科技大学》2015年硕士论文

【摘要】：污泥中含有大量有害物质,如重金属、难生物降解有机物、细菌、病毒、药物和激素等,会造成污泥处理处置较为困难。近年来,由于可利用土地大量减少以及相关法律条规愈发严格,一些传统的污泥处置方法(卫生填埋、堆肥、农业利用以及焚烧等)在应用上受到很大限制。污泥和生物质共气化作为一种新型污泥处置方法,可以实现两种废弃物的优势互补,具有较大的应用潜力。首先在热重分析仪试验台上开展了污泥和松木锯末生物质共热解实验,研究了污泥和松木锯末共热解特性,并分别使用Friedman法和分布活化能模型(DAEM)对污泥和松木锯末共热解过程的动力学特性进行分析。研究结果表明:在本实验研究条件下,污泥和松木锯末共热解过程中不存在明显的协同效应。分别使用Friedman法和分布活化能模型(DAEM)计算出的表观活化能数值相似,均表明热分解过程是多步反应机制。另外,DAEM模拟污泥和生物质共热解所得结论与已知实验结果吻合较好。以油炸干燥预处理过的污泥和松木锯末混合物为原料,基于自行搭建的管式炉固定床反应器,主要研究反应温度(700~900℃)、生物质掺混比例(0%~40%)和氢氧化钙的添加等因素对共气化产物生成特性的影响。研究结果表明:反应温度是影响气化过程的重要因素,H2体积含量从700℃时的27.94%猛增至800℃时的37.53%,而进一步提升至900℃时,H2体积含量几乎没有增加。CO体积含量在800℃时为最小值。随着生物质的掺混比例从0%增加到40%,气体产量逐步增加,氢气体积含量从32.17%逐渐增加到37.53%。通过油炸浸渍法添加Ca(OH)2成本较低,且可以使Ca在原料基质上分散均匀,催化活性较高。H2体积含量由未添加Ca(OH)2时的34.08%猛增至添加后的50.76%,且气体产量明显增加。CO2体积含量也有所上升,反之,CH4和CO体积含量均下降。虽然物理干混添加Ca(OH)2也能显示出一定的催化活性,但与油炸浸渍法相比,其效果要明显减弱。为了解污泥和松木锯末水蒸气共气化过程中焦油的析出特性,分别采用GC/MS和重量分析法对焦油主要成分和焦油产量进行了分析。研究结果表明:高温和Ca(OH)2的加入能促进焦油的裂解。随着反应温度的升高,杂环芳香化合物相对含量下降程度明显,轻质多环芳香烃和重质多环芳香烃相对含量均上升;当生物质掺混比例从0%增加到40%时,焦油产量增加,生物质的掺混对焦油成分影响较大,新增了吡啶、喹啉、异喹啉等含N焦油化合物;通过油炸浸渍法添加Ca(OH)2后,杂环芳香化合物相对含量明显增加,多环芳香烃相对含量下降。
[Abstract]:Sludge contains a large number of harmful substances, such as heavy metals, difficult biodegradable organic matter, bacteria, viruses, drugs and hormones, which will make it more difficult to dispose of sludge. In recent years, some traditional sludge disposal methods (sanitary landfill, composting, agricultural utilization and incineration) have been greatly restricted due to the large reduction of available land and the tightening of relevant laws and regulations. Sludge and biomass co-gasification, as a new sludge disposal method, can realize the complementary advantages of the two kinds of waste, and has great application potential. Firstly, the co-pyrolysis experiments of sludge and pine sawdust biomass were carried out on the thermogravimetric analyzer bench, and the co-pyrolysis characteristics of sludge and pine sawdust were studied. The kinetic characteristics of co-pyrolysis of sludge and pine sawdust were analyzed by Friedman method and distributed activation energy model (DAEM). The results showed that there was no obvious synergistic effect in the co-pyrolysis of sludge and pine sawdust under the experimental conditions. The apparent activation energies calculated by the Friedman method and the distributed activation energy model (DAEM) are similar respectively, indicating that the thermal decomposition process is a multi-step reaction mechanism. In addition, the results obtained from simulated sludge and biomass co-pyrolysis by Daem are in good agreement with the known experimental results. The mixture of pre-treated sludge and pine sawdust was used as raw material, based on a self-built tubular furnace fixed-bed reactor. The effects of reaction temperature (700 鈩，

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