褐煤脉冲式气流干燥传递过程研究

Study on transfer process of lignite drying in an impulse pneumatic dryer

褐煤干燥是褐煤固体热载体新法干馏工艺的重要组成部分。本文对脉冲式气流干燥器内基于气-固两相流的褐煤干燥动量、热量、质量传递过程进行了研究。依托高效成熟的气流干燥技术,以颗粒在气流中的受力情况为基础,建立了气流干燥过程中颗粒加速运动的热量传递模型和颗粒减速运动的动量及热量传递模型,并提出了新的脉冲式气流干燥器高度的设计及优化方法。通过将脉冲式气流干燥器的干燥模拟数据与相同高度的等径式气流干燥器的数据进行对比,验证了脉冲式气流干燥的高效性,并根据烟气温度、颗粒湿含量、体积传热系数等模拟参数沿干燥器高度的分布情况对其高效性的原因进行了详细分析,为脉冲式气流干燥装置工艺设计提供准确的数据依据和理论参考。

Lignite drying is an important part of new retorting technique for lignite using solid heatcarrier.In this paper,transfer process of lignite drying in an impulse pneumatic dryer,includingmomentum,heat and mass transfer,was studied based on two-fluid multiphase flow model.Accordingto air drying technology,which was efficient and mature,a heat transfer mathematical model of particleacceleration and a momentum-heat transfer mathematical model of particle deceleration wereestablished based on the force of particles in the airflow.A new optimization method for the height ofimpulse pneumatic dryer was proposed.The efficiency of the impulse pneumatic dryer was verified bycomparing the data collected from the impulse pneumatic dryer and the traditional pneumatic dryer,which was equal in height with the impulse pneumatic dryer.The reasons for high efficiency of impulsepneumatic dryer were analyzed according to the distribution of the simulation parameters,like gastemperature,particle humidity and volumetric heat transfer coefficient along the height of the dryer.This study provided a data basis and theoretical reference for the design of impulse pneumatic dryers.