The function of three-pass dryer is to achieve required moisture content of dried flakers. The flue gas coming out from the combustion chamber flows to the mixing chamber where the flue gas is mixed with fresh air by proportion to reach certain temperature required by the process control. The flue gas, after going through the multi-cyclone filter, is blew into the core of the drying drum. The flakers are mixed with the flue gas to achieve heat transfer and the moisture of the flakers are evaporated during the flow of flakers. The flakers are floating through the three passing chamber and leave the drying drum with required certain moisture content. The dry flakers are dropped to the downstream process by the rotary discharger under the main cyclone. The exhaust, after going through the multi-cyclone, is partly going to the air via chimney, and partly recycled to the mixing chamber before the dryer feeding. The heat efficiency is improved with the recycling of the exhaust partly.