thermal energy recovery device

The invention relates to a thermal energy recovery device applied to size mixing kettles. The thermal energy recovery device is characterized by comprising a plurality of size mixing kettles (1) and a water storage tank (2), a water inlet of each size mixing kettle (1) is connected with a waste water drainage port, and a water outlet of each size mixing kettle (1) is connected with the water storage tank (2). The thermal energy recovery device has the advantages that thermal energy of waste water can be recovered for preheating of the size mixing kettles, and accordingly thermal energy pollution is reduced while energy saving and cost reduction are realized.