Method for conversion of low temperature heat to electricity and cooling, and system therefore

摘要

A method for producing electrical energy is disclosed which uses a heat source, such as solar heat, geothermal heat, industrial waste heat or heat from power production processes, providing heat of 150° C. or below, further comprising an absorber system in which a working gas, primarily carbon dioxide CO2, is absorbed into an absorbent, typically an amine, further comprising a reactor which receives heat from said heat source and in which the absorbent-CO2 mixture is split into CO2 and absorbent, further comprising an expansion machine, an electricity generator and auxiliary equipment such as pumps, pipes and heat exchangers. The system according to the method allows the cost-efficient production of electrical energy and cooling using low value heat source.

主权项

1. A method for producing electrical energy using an essentially closed loop system comprising the steps of:
providing a reactor (7); accessing at least one external heat source (1) for providing thermal energy to the essentially closed loop system, the at least one external heat source being a low temperature heat source providing thermal energy at up to 150° C.; transferring thermal energy from the at least one external heat source to the reactor (7); providing an absorber system (3) for chemically absorbing carbon dioxide (CO2) into an absorbent liquid to provide a mix of CO2 gas and liquid absorbent (gas-absorbent mix) and to generate a low pressure; providing at least one pump device (6) for increasing the pressure of said gas-absorbent mix and allowing transfer of pressurized gas-absorbent mix to the reactor (7); provding a separator downstream of the pump device for separating said gas-absorbent mix and recycling part of said gas-absorbent mix to said absorber system; using thermal energy from the said heat source (1) to heat the pressurized gas-absorbent mix at the reactor, thereby splitting the pressurized gas-absorbent mix into a heated and pressurized CO2 gas and a heated absorbent liquid as output of the reactor; providing an expansion machine (15) with a generator (23) for producing electricity by expanding the heated and pressurized CO2 gas from the said reactor (7) into a low temperature CO2 gas by using the low pressure generated in the said absorber system (3); providing a pipe system that leads the said heated absorbent liquid exiting the reactor (7) and the low temperature CO2 gas exiting the expansion machine (15) to the said absorber system (3) so the CO2 gas is chemically re-absorbed into the heated absorbent liquid for the process to start over in a reversible reaction with the CO2 gas absorbed into the heated absorbent liquid in said absorber system (3); using said heated and pressurized CO2 gas to operate said expansion machine within a temperature interval between −78° C. and plus 150° C.; using in the absorber system a material capable of binding CO2; obtaining a CO2 pressure in said reactor of between 20 bar and 0.5 bar; obtaining a CO2 pressure in said absorber system of between 0.5 bar and 0.001 bar; the closed loop system continuously recirculating the CO2 gas without its release from the system; and accelerating absorption and mass transfer of CO2 into the absorbent by providing the liquid absorbent in the form of droplets by spraying the liquid absorbent into the absorber such that the gas exiting the expansion machine can be in contact with a large surface constituted by the plurality of absorbent droplets, the droplets having a diameter of between 5 mm and 0.01 mm.