阳离子型聚丙烯酰胺絮凝剂的开发与煤气化黑水处理

Development of cationic polyacrylamide flocculants for treatment of coal gasification black water

煤气化过程产生的黑水通常采用絮凝处理去除悬浮物及部分有机物后循环使用。以丙烯酰氧乙基三甲基氯化铵为阳离子单体,以氧化还原类和偶氮类引发剂为复合引发剂,采用水溶液自由基共聚法制备了一种适用于黑水絮凝处理的阳离子型聚丙烯酰胺。实验结果表明:引发温度为15~20 ℃时,聚合反应较为平稳,1 h后聚合反应结束,于60~80 ℃干燥,得到产品相对分子质量较高,达(734~1 086)×10^4;采用该絮凝剂絮凝处理黑水时,絮体大、沉降速率快,絮凝沉降效果佳;在煤气化装置黑水工况温度下,絮凝剂投加量为3 mg/L时,黑水中悬浮物质量浓度可从114 mg/L降至30 mg/L以下,满足现场使用要求。

The coal gasification black water is usually treated by flocculation method to remove suspended solids and some organic contaminants so as to ensure the reuse of water.Cationic polyacrylamide suitable for flocculation treatment of black water is synthesized through free radical copolymerization in aqueous solution with acryloyloxyethyltrimethyl ammonium chloride as the cationic monomer,and redox initiators and azo initiators as composite initiators.The results show that when the initiating temperature is 15-20℃,the polymerization reaction is stable and completed within 1 h,and after drying at 60-80℃,the product is obtained with high relative molecular weight of(734-1086)×10^4,which is beneficial to form large flocs that are easy to settle in black water,and thus achieves excellent flocculation.The concentration of suspended solids in black water can be reduced from 114 mg/L to below 30 mg/L after adding 3 mg/L of cationic polyacrylamide under the temperature of the coal gasification black water at working condition,which meets the site use requirement.