Procedure for converting low-grade thermal energy into mechanical energy in a turbine for further utilization and plant for implementing the procedure

摘要

This invention relates to a procedure for converting low-grade thermal energy into mechanical energy in a turbine for further utilization and a plant for implementing the procedure. The procedure according to the invention is characterized in that a low-grade heating medium and a first cooling medium are evaporated in a heat exchanger (A). The steam is carried to a turbine (T) for energy conversion and moist steam is carried from here to a heat exchanger (B) for condensing. The condensate is pumped back to the heat exchanger (A), i.e. the steam turbine circuit. Since the heat exchanger (B) is common to the steam turbine circuit described above and a heat pump circuit in such a manner that the heat exchanger comprises a condenser for the steam turbine circuit and an evaporator in the heat pump circuit, the heat removed in connection with condensing can be absorbed by a second evaporating cooling medium the steam of which is pumped via a heat pump (VP) to a heat exchanger (C) which is cooled by cooled medium from the heat exchanger (C) and where condensing takes place. The condensate is carried via an expansion valve (Ex) back to the heat exchanger (B) while outgoing cooled medium from the heat exchanger (A) is either heated in its entirety to a lower level than the original temperature at the commencement of the process or else a partial flow is reheated to a level that is equal to or higher than the original temperature at the commencement of the process and returned to the heat exchanger (A). The purpose of the invention is to provide a procedure and a plant for the conversion of low-grade heat in the form of cooling water or waste heating water from a process of any kind or hot water occurring in nature into mechanical energy in a turbine for further utilization.