A modified Rankine-cycle power-plant without cycle-heat rejection driven by a thermocompressor (ejector) operating in the wet-vapor region, consisting of the following interconnected equipment/processes:
- a) a wet-vapor-region thermocompressor/ejector (10), consisting of:
- a nozzle (11), typically a supersonic one, for acceleration of the high-pressure high-temperature liquid of a working fluid, typically subcooled water or low-quality liquid-gas (water-vapor) mixture, a conical part (12) of the ejector mixing chamber for admission of exhausted wet vapor from a backpressure steam turbine (1), a long constant-diameter part (14) of the said mixing chamber for mixing and deceleration/acceleration of the liquid-gas (water-vapor) mixture, typically in the form of one or more normal shock waves, and a subsonic diffuser (15) for final (subsonic) deceleration of the mixed liquid-gas (water-vapor) mixture;
- b) a cylindrical separator/separation tank (2) for as-complete-as-possible separation of the wet liquid-gas (water-vapor) mixture exiting the said diffuser (15) of the said thermocompressor (10), which can be constructed in any of the following forms:
- (i) a dry-pipe steam separator having of a lot of holes at the top and two holes at the bottom half, whereas the turbulently moving steam-water mixture is directed through the top half holes of the dry pipe and forced to separate between water and steam, whereby the separated steam flows to the said backpressure steam turbine (1) and the separated water drops down to the bulk liquid through bottom holes;
- (ii) a baffle-plate steam separator having the said cylindrical separation tank (2) fitted with typically two (2) to three (3) baffle plates, which serve to change the direction of the incoming steam flow when the steam strikes the baffle plates, prompting heavier water particles contained in the steam-water mixture to fall down to the bottom of the separation tank, while the separated steam is freed from water particles and passed to the said backpressure steam turbine (1);
- or (iii) a centrifugal/cyclone steam separator for more turbulent flows, having the said cylindrical separation tank (2) fitted with at least one cyclone, which utilizes centrifugal force to separate water and steam from the steam-water mixture, whereby the steam-water mixture is forced to move around the cyclone and make the rotation;
- c) the said backpressure steam turbine (1) for adiabatic expansion of the saturated vapor (gas fraction) separated in the said cylindrical separation tank (2), exhausting wet vapor to the said conical part (12) of the said mixing chamber of the said thermocompressor (10), driving a load (8) via a connecting shaft, whereby the expansion pressure ratio of the said backpressure steam turbine (1) is chosen to be equal to the pressure recovery ratio of the said wet-vapor thermocompressor (10), which is obtainable at an ejector entrainment ratio (ratio of mass flow rates of suction and driving fluid) defined by the vapor quality at the outlet of the said diffuser (15);
- d) an optional steam compressor 18 preceding the said backpressure steam turbine (1), mounted on the same connecting shaft with the said load 8 and driven by the said backpressure steam turbine (1), which serves for precompression of the secondary ejector fluid, that is, saturated steam/vapor separated in the said cylindrical separation tank (2), prior to its expansion in the said backpressure steam turbine (1), thus artificially increasing the pressure recovery ratio of the said thermocompressor (10);
- e) the said load (8), typically an electric generator, driven by the said backpressure steam turbine (1) via the said connecting shaft, so that it converts mechanical energy of the said steam turbine (1) into the generator's electrical energy supplied to the grid;
- f) a condensate pump (3) for pressurizing and circulation of the liquid working fluid (saturated water) separated in the said cylindrical separation tank (2);
- g) a stop valve (4) at the discharge side of the said condensate pump (3) for starting up of the said pump (3) and of the entire working-fluid circulation loop;
- h) a liquid/water heater (heat exchanger) (5) for isobaric heat addition to the liquid working fluid, typically subcooled water or a low-quality water-vapor mixture, either directly heated by any fuel or indirectly heated by heat exchange with any source of heat contained in a primary heat-exchange fluid, thereby supplying the heated liquid working fluid to the said nozzle (11) of the said thermocompressor (10), to the end of re-pressurizing of the secondary ejector fluid (exhausted wet vapor from the said backpressure steam turbine (1));
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- i) a method for regulation of the cycle output/load of the proposed modified Rankine-cycle power-plant without cycle-heat rejection in working regimes other than the nominal working regime, in the form of either (1) qualitative regulation of the cycle output/load by alteration of the steam-turbine inlet temperature via the cycle heat input, or (2) quantitative regulation of the cycle output/load by alteration of the steam-turbine mass flow rate using bypassing of the said backpressure steam turbine (1) via a bypass valve
- (16) and a subsequent external cooling of the corresponding portion of the steam-turbine bypass mass flow rate using an external water or air cooler (17), up to the steam-turbine (1) outlet temperature existing in the nominal cycle working regime.