Abstract: A safe and efficient hydrothermal reaction apparatus for converting waste plastic into oil is described herein. The apparatus comprises a receiver tank for containing therein a mixture of plastic and water; a high-pressure injection pump in communication with the receiver tank through a flow passage change-over valve, the flow passage change-over valve being in communication with a water injection passage; a reactor device including a curved piping in communication with the injection pump, the curved piping being provided with a heating means; and an effluent tank in communication with the reactor device through a pressure reducing valve. The flow rate of the mixture injected into the reaction device may be controlled by regulating the pressure reducing valve.

Abstract: A safe and efficient hydrothermal reaction apparatus is described herein. Decomposition or synthesis of object material is performed by the continuous passing of the material through a flow passage of multi-staged reactor units under turbulent flow conditions. The flow passage is formed by a curved or spiral piping. In each reactor unit, a hot plate block is included as a heating unit. The hot plate block and the curved piping are placed in an appropriate thermal contact relationship. A portion of the curved piping is freely supported, so as to accommodate stress caused in the piping under high-temperature/high-pressure conditions. A tank is provided for regulating or controlling the pressure fluctuation within the flow passage which may be caused by solids or powder present or occurring in the flow passage during high-pressure treatment.