脱水污泥厌氧发酵搅拌动力需求试验研究

对于含固率较高的脱水污泥厌氧发酵系统,对物料的搅拌是能耗的重要组成部分,而目前对发酵工艺中机械搅拌动力需求的研究几乎没有。研制了一台卧式强制搅拌干式厌氧发酵反应器,对叶片搅拌过程进行受力分析,计算出理论搅拌扭矩,并以此反应器为基础,研究了污水处理厂脱水污泥的搅拌动力需求。具体研究了污泥的含固率、搅拌转速、反应器填充率等因素对搅拌动力需求的影响,发现低转速下,转速对搅拌扭矩影响非常小,而从搅拌动力需求角度考虑,物料填充率在66.7%~85%之间比较合理。同时还对长期连续搅拌状态下污泥所需的搅拌动力的变化做了研究,发现经过搅拌污泥的内摩擦角和粘聚力出现了较大的变化,从而引起搅拌所需动力在短时间内大幅降低。而原污泥兑水使含固率降低、自由水含量增加时,其搅拌动力需求呈指数趋势减小。

Experimental Study on Power Requirements for Stirring in Dewatered Sludge Anaerobic Digestion

Stirring takes an essential part in energy consumption in an anaerobic digestion system of dewatered sludge with high solids,but little relative research about power requirements for stirring has been done.A horizontal continuous stirred tank reactor for high solids anaerobic digestion were built to study the influence of power requirement brought by sludge solids content,stirring speed and reactor fill level.Force analysis of mixing arms were done and theoretical torsion needs for stirring obtained.Experiments results indicated that changing stirring speed has little effect on power requirements,and the fill level kept between 66.7% and 85% is more reasonable from energy point of view.Some studies were done for dynamic change of power requirement in long-term continuous stirring,showing that the power needs for stirring decline rapidly due to the substantial changes in internal friction angle and cohesive force.The torsion requirements decrease exponentially by adding free water into the sludge.