Wet ammonium chloride raw material from the centrifuge is sent to the fluid bed dryer with built-in heat exchanger through the conveying equipment, wet ammonium chloride and hot air contact in the air cloth plate, ammonium chloride particles are suspended in the airflow, forming fluid, tube heat exchanger is immersed in the fluid state of ammonium chloride, the heat exchanger tube is passed through the steam, and most of the heat required for drying of the material is provided by the tube heat exchanger.