At present, the existing tunnel drying furnaces are generally built by hand, with air ducts in the middle and tunnels on both sides. Furnace flue gas passes through the thicker flue gas pipeline, and hot air is exchanged from the blower flue duct. The furnace body is directly connected with the earth. However, the shortcomings of this dryer are: the temperature is lost, the amount of coal burned is large, the thermal efficiency is low, the hot air exchanged turns back from the air duct to the tunnel on both sides, the hot air is not uniform in the tunnel, the drying material is not uniform, and after drying, the material must be sorted and then dried twice, the drying cost is high, the coal stove can not do anthracite treatment, resulting in environmental pollution.
Tunnel-type fruit and vegetable dryer uses a three-return smokeless hot air stove with a row of tubes. The hot air is directly blown to the material in the tunnel by a high temperature and humidity axial flow fan. The material is placed on the pallets of each layer of the truck. The material enters the tunnel from the end of the tunnel, discharges material from one side of the tunnel near the hot air stove, discharges a truck of dry material, and enters a truck of wet material at the other end to achieve intermittent drying.