The drying tank or drying platform is usually made of refractory bricks or red bricks, and the drying platform also has a cast iron plate as the panel. The waste gas from the combustion of the galvanizing furnace can be used for drying and heating. However, when the galvanizing furnace uses coal and heavy oil as the heating fuel, the combustion waste gas cannot be directly introduced into the drying tank or drying platform with holes. Instead, it should be passed into the heat exchanger to exchange heat with the air in the heat exchanger, and the heated hot air is used to dry the workpiece. In order to ensure a high and uniform temperature in the drying tank, the drying tank must be equipped with a thermal insulation cover, which shall be made into a movable type.