3种内筒溢流型溶气罐结构改进设计方案的溶气性能对比分析

溶气罐是溶气释放式微气泡发生系统的关键设备，其中内筒溢流型溶气罐具有结构简单、成泡粒径小等优点。提出了3种内筒溢流型溶气罐的结构改进设计方案，并对其在不同操作参数下的溶气性能进行了对比分析。为克服通过测量释气量间接表征溶气量所带来的系统误差，建立了在线带压测量溶解氧的方法，并以空气在水中溶解量的变化率(即溶气效率)来直接表征溶气罐的溶气性能。结果表明：溶气效率随气液比和溶气压力的增大而增加，随液位比的升高而减小；在相同气液比、液位比及溶气压力下，气液切向进口加螺旋导叶片型溶气罐的溶气效率最高。采用响应曲面法对溶气性能相对最佳的内筒溢流型溶气罐的操作参数进行优化，预测最高溶气效率为72.43%时的最佳操作参数为：气液比为0.25，液位比为0.36，溶气压力为0.26 MPa。所得回归模型预测值与实测值的相对误差为0.87%，表明该模型可较好地分析和预测溶气罐的溶气性能。

Comparison and analysis of dissolved gas performance of three improved design schemes of internal cylinder overflow type dissolved gas tank

Dissolution tank is the key part of the pressure dissolution type microbubble generator. The dissolution tank with vertical inner cylinder has the advantages of simple structure and ability to generate small bubbles. Here, three modified dissolution tanks were proposed based on the classical structure of vertical inner cylinder and the air dissolving performance was compared under different operation conditions. To eliminate the experimental error caused by indirect measurement, the dissolved air concentration was directly measured under pressure by an on-line oxygen content measurement system. The air dissolving performance is then directly indicated by the change of air dissolved concentration. The result showed that the air dissolving efficiency increased with gas-liquid ratio and dissolution pressure, and decreased with liquid level in a tank. With the same operational parameters, the modified dissolution tank with gas-liquid tangential inlet and spiral guide vane exhibited the best air dissolution performance. The operation parameters of the best-performing modified dissolution tank were optimized by the response surface method, and the optimal operating parameters are obtained as follows: gas-liquid ratio was 0.25, liquid level ratio was 0.36, and dissolved gas pressure was 0.26 MPa. The relative error between the predicted value of the regression model and the experimental data was about 0.87%, indicating that the model can be used in further analysis and prediction of the air dissolution performance.