响应面试验优化甘薯渣流化床干燥工艺

Optimization of Fluidized Bed Drying of Sweet Potato Residue by Response Surface Methodology

甘薯渣在传统干燥时,易发生黏结、结块的现象,为了改善这种状态,本研究以甘薯渣为原料,采用Box-Behnken优化试验研究流化床甘薯渣单位面积加载量、床层温度、空气流量3个因素对甘薯渣干燥时间和甘薯渣粒度综合评分的影响,并对流化床干燥甘薯渣的工艺条件进行了优化。结果表明:对流化床干燥甘薯渣综合评分的影响大小顺序为单位面积加载量>空气流量>床层温度,从回归模型中得到最佳工艺参数为单位面积加载量5 264 g/m^2、空气流量52.73 m^3/h、床层温度51.33℃,此条件下综合评分预测值为0.790,验证实验结果预测精度为93.60%。与传统干燥方式相比,干燥时间缩短,流化床干燥制得的样品20目过筛率82.3%,堆积密度为0.446g/mL,密度明显提高25.8%;硬度485.382 g,且硬度明显减小;扫描电镜中颗粒内部空隙增大,样品松散,可减小粉碎成本。本研究结果为工业化干燥、延长保存时间及其深加工生产提供理论依据。

Adhesion and agglomeration easily occur during the traditional drying process of sweet potato residue. In order to improve this phenomenon, the process parameters for the fluidized bed drying of sweet potato residue, i.e., material loading per unit area, bed temperature, air flow rate, were optimized using response surface methodology with a BoxBehnken design. The weighted average of dimensionless drying time and granularity was used as response variable. The results showed that the response was influenced in decreasing order by material loading per unit area, air flow rate and bed temperature. The optimal conditions obtained from the regression model were as follows： loading capacity, 5 264 g/m^2; air flow rate, 52.73 m^3/h; and bed temperature, 51.33 ℃. Under these conditions, the predicted response value was 0.790, and the validation experiments showed a prediction accuracy of up to 93.60%. Compared with traditional drying method, the time required for fluidized bed drying was shortened. Additionally, 82.3% of the dried product could pass through a 20-mesh sieve, bulk density of the sample was 0.446 g/mL, which was significantly increased by 25.8%, and hardness was 485.382 g, which was significantly reduced. Under scanning electron microscopy, it was observed that the fluidized bed dried product exhibited particles with larger internal voids and had a looser structure, leading to reduced comminution cost. This study may provide a theoretical basis for industrial drying, prolongation of the storage time and intensive processing of sweet potato residue.