An auxiliary heat exchanger that is used in conjunction with thermoplastic melter kettles. The auxiliary heat exchanger receives molten thermoplastic material from the bottom of a melter kettle, transports the molten thermoplastic material though the auxiliary heat exchanger and feeds the molten thermoplastic material into the top of the melter kettle thereby mixing hotter molten thermoplastic material from the bottom of the melter kettle into cooler thermoplastic material near the top of the melter kettle. The auxiliary heat exchanger includes an oil bath chamber and parallel heat transfer tubes that are arranged in a serpentine configuration and include motor drive augers to transport molten thermoplastic material through the auxiliary heat exchanger.

A method of heating up a furnace bottom and a burner lance used in the method are proposed. The method of heating up the furnace bottom includes a step of opening, in the tap hole, a burner lance insertion hole having a diameter larger than a diameter of the burner lance so as to penetrate into the furnace, a step of installing the burner lance in the opened burner lance insertion hole, a step of filling a gap between the installed burner lance and a furnace exterior side of the tap hole with a refractory, and a step of blowing in gas for heating into the furnace from the burner lance to heat up the furnace bottom.

An auxiliary heat exchanger that is used in conjunction with thermoplastic melter kettles. The auxiliary heat exchanger receives molten thermoplastic material from the bottom of a melter kettle, transports the molten thermoplastic material though the auxiliary heat exchanger and feeds the molten thermoplastic material into the top of the melter kettle thereby mixing hotter molten thermoplastic material from the bottom of the melter kettle into cooler thermoplastic material near the top of the melter kettle. The auxiliary heat exchanger includes an oil bath chamber and parallel heat transfer tubes that are arranged in a serpentine configuration and include motor drive augers to transport molten thermoplastic material through the auxiliary heat exchanger.

A method of heating up a furnace bottom and a burner lance used in the method are proposed. The method of heating up the furnace bottom includes a step of opening, in the tap hole, a burner lance insertion hole having a diameter larger than a diameter of the burner lance so as to penetrate into the furnace, a step of installing the burner lance in the opened burner lance insertion hole, a step of filling a gap between the installed burner lance and a furnace exterior side of the tap hole with a refractory, and a step of blowing in gas for heating into the furnace from the burner lance to heat up the furnace bottom.