生物质型煤热风干燥特性及模型研究

Bi-briquette hot air drying characteristics and model

为降低生物质型煤干燥成本,提高干燥效率,研究热风干燥风速和温度对热风干燥特性的影响,拟合了生物质型煤在不同热风干燥条件下水分随时间变化的模拟曲线。结果表明:生物质型煤与多数多孔介质类似,干燥过程可分为加速干燥、恒速干燥、降速干燥3个阶段,其中恒速干燥阶段的干燥时间约25 min;热风温度越高,风速越大,生物质型煤的干燥速率越大,干燥时间越短,干燥时的裂纹率也越高。当干燥温度180℃,风速1.2 m/s时,生物质型煤热风干燥效果较好,干燥热效率最高为48.34%。通过对不同温度、风速条件下的生物质型煤干燥试验数据与常用干燥模型进行拟合分析,发现Sabbet干燥模型拟合度最好,当干燥温度180℃,风速1.2 m/s时相关性系数为0.997,二者相关性显著,因此Sabbet干燥模型可较好地反映生物质型煤在不同温度、风速下的干燥特性。

To reduce the cost of bi-briquette drying and improve the drying efficiency,by investigating the influence of hot air velocity and temperature on drying characteristics, fit the simulation curve which represents the water change law with drying time. The results show that：the bi-briquette is similar with most of porous mediums.The drying process can be divided into raising speed drying phase, constant speed drying phase and reducing speed drying phase.The drying time of constant speed stage is only 25 minutes.The drying rate of biomass briquette increases with the rise of drying temperature and air flow velocity.Meanwhile, the creak rate is higher.When the drying temperature is 180℃ ,wind speed is 1.2 m/s, the drying effects is better, the thermal efficiency of drying is 48.34 percent.Conduct fitting analysis of drying experimental data of biomass briquette with four common models under different temperatures and velocities. When the drying temperature is 180 ℃, air flow speed is 1.2 m/s ,the correlation coefficient is 0.997 ,the simulated curve and the experimental curve coincide, Sabbet model fits and reflects the drying characteristics of biomass briquette under different temperatures and air velocities better.