Hot airflow type sawdust dryer, also called pipeline type drying machinery, adopting twice circulate heating system, is our newly developed advanced drying equipments, and show the features of automatic feeding, high hot airflow speed, fully mixing of airflow and materials, big drying strength, lower dust and bigger drying capacity. Moisture in the raw mateials of less than 40% can be drying one time to meet the requirement for coal bar production, which greatly reduced the labor intensity compared with commonly used drier.