螺旋进气增强气力清淤性能试验研究

Experimental study on performance enhancement of airlift dredging by swirl injection

为了提高气力清淤浓度和效率,引入轴向螺旋式进气,采用普通河砂模拟淤积层,以池底供砂方式进行试验,以进气螺旋角为变量,研究螺旋气力清淤性能特性。结果显示:引入轴向螺旋式进气,气力清淤性能随之提高,性能曲线呈驼峰式发展;进气螺旋角θ为10°时气力清淤性能最佳,其排固量和提升效率性能峰值比传统气力清淤分别提高28%和14%。此外,气力泵吸口高度(即气力泵吸口至砂层距离)H <0时,系统排固量和排固浓度进一步提高,淤积砂层出现坍塌和流动,形成以气力泵为中心的倒圆锥形砂坑,砂坑体积随气力泵埋入深度的增加而增加。临界试验表明,螺旋气力清淤的液-固起动所需气量值明显小于传统气力清淤,具有高效率、低能耗等明显优势。试验契合工程实际,对清淤工程应用具有一定指导意义。

In order to improve the concentration and efficiency of airlift dredging,ordinary river sand was used to simulate the siltation layer,a new particle feeding method which is similar to the real situation was proposed,and a new type of swirl air injection was introduced to investigate the airlift dredging performance.The experimental results show that the performance of airlift dredging is improved with the introduction of swirl air injection,and the performance curve shows a hump development. Solids mass flow rate and lifting efficiency of the swirl airlift dredging operating at the angle of 10° are improved by 28% and 14% respectively over those of conventional airlift dredging. In addition,the concentration and solids mass flow rate of airlift system are especially further improved in the case of the suction height of airlift pump(i.e.,distance from suction of airlift pump to sand layer) H < 0,the silted sand layer collapses and flows obviously,forming an inverted conical pit with the airlift pump as the center,and the volume of sand pit increases with the increase of the embedding depth of the airlift pump. The critical experiment shows that the liquidsolid starting airflow volume for swirl airlift dredging is obviously less than that for conventional airlift dredging,which has obvious advantages of high efficiency and low energy consumption.The experiment agrees with the engineering practice and has a high guiding value to the dredging application.