Hardwood variable-frequency combined energy-saving drying system and drying method

The invention relates to a hardwood variable-frequency combined energy-saving drying system and drying method. The system comprises a steam heater arranged on the outer side of a material stack, a fan, a condenser, a moisture removal evaporator and a heat pump evaporator, wherein the steam heater and condenser supply hot air to the material stack; the moisture removal evaporator is used for removing moisture of the material stack; the fan is connected with a frequency converter; the condenser is connected with the moisture removal evaporator through a pipeline; and the heat pump evaporator is connected with the moisture removal evaporator in parallel through a first pipeline and a second pipeline. The method comprises the following steps: setting a kiln by using hardwood, heating by variable-frequency conventional steam to preheat the hardwood board, carrying out early-stage and medium-stage drying by using the variable-frequency heat pump, carrying out finish treatment in the variable-frequency conventional steam drying later stage, and discharging. The system and method solve the problems of high energy consumption, long drying time and low efficiency in the conventional steam drying, and belong to the fields of industry energy saving, environment protection and resource saving.