A two-dimensional model based on the theory of Markov chain has been developed to determine the Residence Time Distribution (RTD) of municipal sewage sludge in a double-axis continuous paddle dryer. Based on the experiments, the paper proposes further corrections to simulate the transition. To characterize the sludge transition in the dryer, the parameter of internal recirculation based on one dimensional model is further developed. In addition, two parameters, the internal forward coefficient between two axes and the internal forward coefficient in one axis are introduced to characterize the new model. In absence of available correlation, solid hold-up of each cell in dryer and both the recirculation parameters are identified by fitting the model to experiments. Through analysis, the model demonstrates its ability to describe the sludge flow in a double-axis continuous paddle dryer by the experimental and simulation RTD curve. Finally, an analysis of influence factors highlights that recirculation coefficients are critical for the model while solid hold-up H_u of each cell controls the mean residence time and the final moisture content. In addition, the geometric residence time of sludge flow has a negligible effect on sludge flow for it has no effect on dimensionless variance. Moreover, compared with the recirculation coefficient between different axes R, the recirculation coefficient in one axis r has a negligible effect. In addition, recirculation parameters have no effect on mean residence time of sludge flow.

建立了基于马尔可夫链理论的二维模型，以确定双轴连续桨式干燥机中城市污水污泥的停留时间分布（RTD）。在实验的基础上，本文提出了进一步的修正以模拟过渡过程。为了表征干燥机中的污泥过渡，进一步开发了基于一维模型的内部再循环参数。另外，引入两个参数，两个轴之间的内部正向系数和一个轴上的内部正向系数来表征新模型。在没有可用的相关性的情况下，通过将模型拟合到实验中来确定干燥器中每个单元的固体滞留量和两个再循环参数。通过分析，该模型证明了通过实验和模拟RTD曲线描述双轴连续桨式干燥机中污泥流量的能力。最后，对影响因素的分析表明，再循环系数对模型至关重要，而固体滞留率每个单元的H _u控制平均停留时间和最终水分含量。此外，污泥流的几何停留时间对污泥流的影响可以忽略不计，因为它对无量纲的方差没有影响。此外，与不同轴R之间的再循环系数相比，一个轴r中的再循环系数的影响可忽略不计。另外，再循环参数对污泥流的平均停留时间没有影响。