典型褐煤脱水提质及所脱水分的净化回收研究

发布时间：2018-03-18 21:56

本文选题：褐煤　切入点：脱水方式　出处：《浙江大学》2015年硕士论文　论文类型：学位论文

【摘要】：我国褐煤资源丰富,主要分布在内蒙古、东北、云南等地区,多为干旱缺水地区。褐煤的高水分含量(20%-50%)使得燃烧前必须进行脱水提质。本文将褐煤提质过程中脱除的水分加以收集,通过水质检测与净化,将褐煤冷凝水处理成为可回收的二次工业水,以便减少电厂用水量,缓解当地用水压力。本文采用蒸发、微波及水热三种脱水方式对褐煤进行脱水改性并回收所脱水分。分别进行了煤质分析、水分检测、净化回收等试验,比较三种脱水方法的脱水效率、褐煤改性程度、冷凝水污染程度、冷凝水净化难易等方面,以期找到最佳处理方法,为褐煤冷凝水净化回收的工业应用提供可行性参考。通过对改性前后煤样的煤质组成、微观形貌、孔隙结构等微观理化性质进行研究分析,可知三种脱水方式都能不同程度地脱除褐煤水分,且脱水效率随工况温度／功率增加而增加,改性煤能量密度增加,煤阶升高,孔隙结构有所发展。综合脱水效率与煤质改性程度可知,微波和水热两种改性方法远远优于蒸发改性方法,更适于作为褐煤改性及水分回收方式。通过检测水分的化学需氧量、氨氮、总磷、硬度、离子、有机化合物等指标,对褐煤冷凝水进行水质分析,结果表明三种处理方式下褐煤冷凝水的成分含量相差甚远,蒸发水和微波水较接近工业用水标准,利于净化回收,水热水各项水质指标均大大超出标准范围,且在250℃工况下杂质含量达到最大。另外,三种冷凝水中均检测到微量有毒金属元素、有毒致癌的多环芳烃及酚类化合物,这将成为后续研究工作的重点。对水热冷凝水进行絮凝沉淀-过滤净化试验,分别采用聚合氯化铝(PAC)、聚合氯化铝铁(PAFC)、聚丙烯酰胺(PAM)三种絮凝剂,通过絮凝剂粗化试验、细化实验和pH调节实验确定了三种絮凝剂的最佳絮凝条件。由实验结果可知,PAC和PAFC两种絮凝剂絮凝效果相近,絮凝剂用量多,絮体沉降速度较慢,未能形成固状矾花,絮凝时间长,含水量大；PAM絮凝过程中絮凝剂用量少,矾花生成速度快,呈絮体固状物,较密实,细碎絮体少,有利于矾花与水分离。因此,综合净化效率与经济性,PAM絮凝效果优于PAC及PAFC。对絮凝后水热出水和蒸发、微波原水进行活性炭吸附实验,可知活性炭投加量、吸附时间及水体pH值为影响活性炭吸附的重要因素,由实验结果可得：三种混合水的最佳吸附时间均为60min,最适宜酸碱环境为弱酸性,水热水最佳活性炭投加量为500g/L,微波、蒸发水最佳活性炭投加量为50g/L即水热净化成本最高。三种活性炭出水通过超滤膜过滤进行深度处理,处理后三种终水杂质含量相近,有机物含量大幅减少,阴阳离子种类与含量较初水变化不大,COD、NH3-N、TP、浊度等水质指标都已降低至标准范围,因此经过絮凝沉淀-过滤、活性炭吸附、超滤膜过滤的一系列净化处理,蒸发、微波、水热三种冷凝水水质指标均达到工业二次用水水质标准。
[Abstract]:China's rich lignite resources, mainly in Inner Mongolia, Northeast China, Yunnan and other regions, mostly arid regions. The high water content of lignite (20%-50%) which must be dehydrated before burning. The quality and process of water removal of lignite quality collected, through the water quality detection and purification, will become the two lignite condensed water treatment industrial water Recyclable, in order to reduce the power consumption, alleviate local water pressure.
This paper uses evaporation, dehydration and recovery of the modified water removal of Lignite by microwave and hydrothermal dewatering. Three were coal quality analysis, moisture detection, purification and recovery tests, the dehydration efficiency comparison of three kinds of dehydration method, modified lignite, condensed water pollution degree, condensed water purification difficulty hand, in order to find the best treatment method, in order to provide a reference for industrial application of lignite condensate purification recovery.
In order to improve coal quality of coal samples, before and after the research and analysis of micro morphology, physicochemical properties of pore structure, the three dehydration methods can remove lignite moisture in different degrees, and the dewatering efficiency with temperature / power increases, the modified coal energy density increase, coal rank increasing pore the structure has the development. Comprehensive dewatering efficiency and coal quality modification degree of the two kinds of microwave and hydrothermal modification method is much better than that of evaporation modification method, more suitable for lignite modification and water recycling.
Through the detection of chemical oxygen water, ammonia nitrogen, total phosphorus, hardness, ion, organic compounds and other indicators, analysis of water quality for lignite condensate, results show that the content of lignite condensate under three treatments far, evaporation of water and microwave water is close to the standard of industrial water, water purification and recovery for the hot water. Water quality indicators are far beyond the standard range, and at 250 DEG C under the condition of impurity content reached the maximum. In addition, three kinds of condensed water were detected in trace toxic metals, polycyclic aromatic hydrocarbons and phenolic compounds are toxic carcinogens, which will become the focus of future research work.
Flocculation, filtration and purification test on the water and heat condensate, respectively using polyaluminum chloride (PAC), polyaluminum ferric chloride (PAFC), polyacrylamide (PAM) of three kinds of flocculant, flocculant by coarsening experiment, refining experiment and pH control experiments to determine the optimum flocculation conditions of three kinds of flocculant by the experimental results. Effect of two kinds of coagulants, PAC and PAFC were similar, flocculant dosage, floc settling velocity is slow, failed to form a solid alum, flocculation time, water; less dosage of flocculant PAM process, alum generation speed, a floc solid, relatively compact, fine flocs less conducive to the separation of alum flowers and water. Therefore, the comprehensive purification efficiency and economy, the flocculation effect is better than that of PAC and PAFC. PAM
After flocculating hydrothermal water and raw water evaporation, microwave activated carbon adsorption experiment showed that activated carbon dosage, adsorption time and pH value of water is an important factor affecting the adsorption of activated carbon, according to the experimental results: the best adsorption time of three kinds of mixed water were 60min, the most suitable pH environment is weak acidic water, hot water the best activated carbon dosage was 500g/L, microwave, water evaporation optimum activated carbon dosage of 50g/L hot water purification cost is the highest.
Three kinds of activated carbon effluent through ultrafiltration membrane for treatment, after the treatment of three kinds of final water content of impurities is similar to that of the organic matter content is greatly reduced, the kinds and contents of ions than the original water changed little, COD, NH3-N, TP, turbidity and other water quality indicators have been reduced to the standard range, so after flocculation and filtration. Activated carbon adsorption, ultrafiltration membrane, a series of purification, evaporation, microwave, hot water of three water quality indicators have reached two times of industrial water quality standards.

【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD849.2;X752

【参考文献】