Effects of aquatic feed layer thickness on distribution of airflow velocity on feed layer surface in belt dryer

Moisture content of the aquatic feed after extruder is frequently high in the production process, and drying is necessary to reduce moisture content of the aquatic feed. The thickness of feed layer is an important parameter during the aquatic feed drying. On one hand, the thickness of feed layer represents the capacity of the belt dryer per unit time(the thicker the feed layer, the higher the productivity), which affects the working energy consumption of the belt dryer. On the other hand, the thickness of feed layer also affects airflow distribution inside the belt dryer, thus affecting the distribution uniformity of airflow velocity on the surface of feed layer. The airflow velocity on feed layer surface directly influences the moisture content of aquatic feed after drying, and the uniformity of airflow velocity on feed layer surface directly influences the uniformity of moisture content of aquatic feed. In this paper, effects of aquatic feed layer thickness on airflow distribution in belt dryer and airflow velocity distribution on feed layer surface was studied. Firstly, three different kinds of internal airflow distribution inside the belt dryer were simulated using computational fluid dynamics (CFD), corresponding to three kinds of feed layer thicknesses (20, 30, 40 mm). Secondly, a belt dryer was designed and manufactured as the experimental platform based on the actual production needs in the National Feed Processing Equipment Engineering and Research Center. Thirdly, three series of experiments were conducted using the experimental platform corresponding to three kinds of feed layer thickness (20, 30, 40 mm), and repeated three times in every series of the experiment. Before the experiment, nine airflow velocity sensors were placed at nine points on the surface of the feed layer in order to measure the airflow velocity values of that nine points during the experiment. After the simulations and experiments, not only the simulation results of the airflow velocity distribution on the feed layer surface and experimental results of that were compared, but also the difference of airflow velocity distribution on feed surface between different feed layer thickness were compared. Results showed that the trend of airflow velocity distribution in simulation results and experimental results were consistent, which proved the simulations and experiments in this paper were reliable. Besides, the error between simulations and experimental results were also explained in this paper. According to the simulation and experimental results, aquatic feed layer thickness affected the airflow distribution inside the belt dryer and the airflow velocity distribution on the feed layer surface. When the feed layer thickness was 20 mm, the airflow velocity uniformity of airflow velocity distribution was not good. But when the feed layer thickness was 40 mm, airflow velocity uniformity of airflow velocity distribution was respectively good. The research in this paper provides theoretical guidance for the selection of feed layer thickness parameters in actual production of belt dryers, which can reduce the moisture content of aquatic feed and make the moisture content uniformity of aquatic feed good after drying.