Performance Optimization and Numerical Simulation Study of Sludge Low-Temperature Drying System

Abstract

Sludge production increases year by year, which causes great environmental pressure. Low-temperature sludge drying technology is a kind of technology with energy conservation and environmental protection, which is widely favored by the sludge drying industry. The distribution of airflow in the drying chamber is the key factor affecting the drying performance of sludge drying system. In this paper, a uniform flow structure was designed, and a numerical simulation study of the designed flow field in the designed drying chamber was carried out by STAR-CCM+ software. The uniform flow structure of the sludge drying chamber and the optimal flow field distribution conditions on the drying chamber and conveyor belt were obtained so that the uniformity of air distribution in the sludge drying chamber and conveyor belt was improved, and the drying performance of the sludge low-temperature drying system was improved. The effectiveness of the numerical simulation was verified by experiments. The experimental results showed that when the number of shunt plates is three, the shape is an involute arc plate, the distance between the first and third shunt plate is 1,600 mm, and the distance between the second and first shunt plate is 700–900 mm. The flow field distribution on the drying room and the conveyor belt was the most uniform when the inlet wind speed was between 25 and 35 m/s. In addition, there is a strong correlation between the experimental results and the simulation results, which can prove the effectiveness and reliability of the numerical model. The airflow distribution inside the drying room was very uneven: the airflow would change direction with the shape of the obstacle, and the direction of airflow movement was easily affected by the shape of the shunt plates. Therefore, the shape of the shunt plates of the flow sharing structure was different, and the effect of the flow field was also different. Therefore, it was necessary to optimize the distribution uniformity of the flow field in the drying room. STAR-CCM+ software was used to optimize the flow field of the drying room, and the distribution of the velocity field was mainly considered. Through numerical simulation, the shape, quantity, and layout of the flow sharing structure were simulated and optimized, and the flow sharing structure that could improve the uniformity of air distribution in the drying room was designed. As long as these problems are solved, the low-temperature drying system could greatly improve the energy consumption of sludge dewatering, carry out sludge reduction treatment, and also be applied in large-scale industrialization, greatly reducing the problem of sludge treatment and reducing the environmental pollution.