Method for preparing polyester polyol for rigid polyurethane foam from polyester waste residues

The invention discloses a method for preparing polyester polyol for rigid polyurethane foam from polyester waste residues. The method comprises the following steps: treating the polyester waste residues generated by a polyester production device and kettle residual liquid generated by an ethylene glycol production device, adding other micromolecular polyols, feeding the formed mixture into a reactor, carrying out heating for dissolving, adding a catalyst, continuing heating to raise a temperature to 220-245 DEG C, starting timing when a first drop of a distillate is produced, conducting reacting for 2-6 hours, performing cooling, and carrying out filtering when the temperature is reduced to be lower than 100 DEG C so as to obtain viscous liquid, namely a polyester polyol product. The polyester polyol is added into a foaming agent formula to prepare cheap rigid polyurethane foam with good foaming performance. According to the invention, valuable and resource utilization of the waste residues and the waste alco