Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F22—STEAM GENERATION
  • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
  • F22B1/00—Methods of steam generation characterised by form of heating method
  • F22B1/02—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers
  • F22B1/18—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers the heat carrier being a hot gas, e.g. waste gas such as exhaust gas of internal-combustion engines
  • F22B1/1807—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers the heat carrier being a hot gas, e.g. waste gas such as exhaust gas of internal-combustion engines using the exhaust gases of combustion engines
  • F22B1/1815—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers the heat carrier being a hot gas, e.g. waste gas such as exhaust gas of internal-combustion engines using the exhaust gases of combustion engines using the exhaust gases of gas-turbines
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
  • F01K17/00—Using steam or condensate extracted or exhausted from steam engine plant
  • F01K17/02—Using steam or condensate extracted or exhausted from steam engine plant for heating purposes, e.g. industrial, domestic
  • F01K17/025—Using steam or condensate extracted or exhausted from steam engine plant for heating purposes, e.g. industrial, domestic in combination with at least one gas turbine, e.g. a combustion gas turbine
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
  • F01K23/00—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids
  • F01K23/02—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled
  • F01K23/06—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle
  • F01K23/10—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle with exhaust fluid of one cycle heating the fluid in another cycle
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E20/00—Combustion technologies with mitigation potential
  • Y02E20/14—Combined heat and power generation [CHP]

Definitions

• the present invention relates to a combined-cycle plant for the production of electric and thermal energy and to a method for operating such a plant .
• a combined-cycle plant for the production of electric and thermal energy generally comprises a gas turbine unit, a steam turbine unit, a boiler and a district-heating unit, provided with a heat exchanger supplied with steam drawn from the steam turbine unit.
• the steam turbine unit comprises a low-pressure steam turbine, a medium-pressure steam turbine, a high- pressure steam turbine and a condenser.
• the steam used to supply the heat exchanger is drawn upstream of the low-pressure steam turbine.
• the amount of thermal energy which may be generated by the district-heating unit is thus limited by the amount of steam which should necessarily evolve in the low-pressure steam turbine .
• the present invention relates to a combined-cycle plant for the production of electric and thermal energy comprising:
• a steam turbine unit comprising a low-pressure steam turbine
• a district-heating unit comprising:
• thermoelectric heat exchanger for transferring heat to a district-heating fluid; the heat exchanger being provided with a condensate collecting vessel;
• a flash tank vessel which is designed to receive condensate from the condensate collecting vessel and to generate and supply steam to a first point upstream of the inlet of the low pressure steam turbine .
• the present invention relates to a method for operating a combined- cycle plant for the production of electric and thermal energy comprising:
• a steam turbine unit comprising a low-pressure steam turbine
• a district-heating unit comprising a heat exchanger for transferring heat to a district-heating fluid; the heat exchanger being provided with a condensate collecting vessel;
• the method comprising the step of generating steam from the condensate of the condensate collecting vessel by means of a flash tank vessel and the step of supplying the generated steam to a first point upstream of the inlet of the low-pressure steam turbine .
• reference number 1 indicates a combined-cycle plant for the production of electric and thermal energy comprising a gas turbine unit 2, a steam turbine unit 3 , a boiler 4 , a steam circuit 5 and a district-heating unit 6.
• the gas turbine unit 2 is the first engine of the combined-cycle plant 1 and may be supplied with both gas and diesel .
• the gas turbine unit 2 is connected to a generator 8 and comprises a compressor 9, a combustion chamber 10, a gas turbine 11 and a shaft 12 pivoting around an axis of the gas turbine 11 to operate the generator 8.
• the steam turbine unit 3 is coupled with a generator 14 and comprises a shaft 15 , a high-pressure turbine 16, a medium-pressure turbine 17, a low-pressure steam turbine 18 and a condenser 19.
• Boiler 4 extends from the outlet of the gas turbine unit 11 to the intake 22 of a chimney (not shown in the figure) and recovers the residual heat of the combustion fumes generated by the gas turbine unit 2.
• boiler 4 contains a part of the steam circuit 5 and comprises a fumes flowing chamber 21, through which the exhaust fumes from the gas turbine unit 2 flow.
• the combustion fumes from the gas turbine unit 2 are substantially supplied in direction Dl into the fumes flowing chamber 21, while the steam is substantially supplied in a direction D2 opposite to direction Dl .
• the steam circuit 5 supplies the steam turbine unit 3 and passes through boiler 4.
• the steam circuit 5 comprises a line 24, which connects condenser 19 to boiler 4 and along which a pump 25 is arranged to extract the condensate from condenser 19.
• Line 24 supplies a thermal exchange module 26, which is arranged inside the fumes flowing chamber 21 at the chimney intake 22 and serves the function of rising the temperature of the condensate from condenser 19.
• line 24 Downstream of the thermal exchange module 26 in direction D2, line 24 supplies an evaporator/degasser 28, which is inside boiler 4, a recirculation line 29, which extends outside boiler 4, and a condensate draw line 31 which, as will be described in more detail below, supplies a heat exchanger of the district-heating unit 6.
• the recirculation line 29 comprises a recirculation pump 30 and serves the function of rising the condensate temperature in order to avoid condensation phenomena of the aqueous vapour contained in the fumes .
• the steam circuit 5 has a low-pressure delivery line 32 to supply the low-pressure steam turbine 18, a medium- pressure delivery line 33 to supply the medium-pressure steam turbine 17, and a high-pressure delivery line 34 to supply the medium-pressure steam turbine 16.
• the low-pressure delivery line 32 connects the evaporator/degasser 28 to the low-pressure steam turbine 18 and is connected to an outlet line 36 of the medium-pressure steam turbine 17.
• the low-pressure delivery line 32 comprises a low-pressure thermal exchange module 37 and an inlet valve 38, which regulates the amount of steam entering the low-pressure steam turbine 18.
• the medium-pressure delivery line 33 comprises a plurality of medium-pressure thermal exchange modules 38, a medium-pressure superheater 40 and a de- superheater 41, which comes into operation whenever the steam temperature is too high.
• the high-pressure delivery line 34 comprises a plurality of high-pressure thermal exchange modules 42, a high-pressure superheater 43 and a de- superheater 44, which comes into operation whenever the steam temperature is too high.
• the district-heating unit 6 comprises a condensate draw line 31, a steam draw line 45, a heat exchanger 46, a condensate collecting vessel 47 to collect the condensate generated in the heat exchanger 46, and a quick evaporation vessel 48, commonly called “flash tank” .
• the heat exchanger 46 transfers the heat of the condensate from the condensate draw line 31 and the heat of the steam from the steam draw line 45 to a district- heating fluid.
• the district-heating fluid is preferably water and is usually used for domestic and industrial heating systems.
• the flash tank vessel 48 is subjected to depressurization between the inlet and the outlet, which determines the quick evaporation of a part of the condensate from the condensate collecting vessel 47, which is under saturation conditions.
• the pressure upstream of the flash tank vessel 48 is, in fact, higher than the pressure downstream of the flash tank vessel 48.
• the pressure upstream of the flash tank vessel 48 is equal to the pressure of the condensate collecting vessel 47 and is between about 1.7 and about 3.5 bar, preferably about 2.5 bar.
• the pressure downstream of the flash tank vessel 48 is equal to the inlet pressure of the low-pressure steam turbine 18, which is usually slightly higher than the pressure of condenser 19.
• the pressure downstream of the flash tank vessel 48 is between about 0.02 bar and 0.06 bar, preferably 0.03 bar.
• the steam generated by the flash tank vessel 48 is supplied to the inlet of the low-pressure steam turbine 18. Namely, the steam generated by the flash tank vessel 48 is supplied to a point downstream of the inlet valve 38.
• the district-heating unit 6 further comprises a condensate discharge line 49 which connects the flash tank vessel 48 to the line 24 of the steam circuit 5 and which allows the condensate generated in the flash tank vessel 48 to be discharged.
• the condensate generated by the heat exchanger 45 is advantageously transformed into steam which may be used again to supply the low-pressure steam turbine 18.
• the amount of steam which supplies the heat exchanger 46 and which is drawn through the steam draw line 45 may be increased. This results in an increase of about 7% in the thermal power generated by the district-heating unit.
• the condensate drawn through the condensate draw line 31 contributes to increase the thermal power produced by the district-heating unit 6 by about 7%.
• the heat used to heat the condensate drawn from the condensate draw line 31 is the heat which is usually discharged through the chimney intake 22 of boiler 4 and which is not normally exploited.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Sustainable Development (AREA)
• Sustainable Energy (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Engine Equipment That Uses Special Cycles (AREA)

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Cited By (2)

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Family Cites Families (4)

• 2009
  • 2009-12-29 IT ITMI2009A002315A patent/IT1397210B1/it active
• 2010
  • 2010-12-29 WO PCT/IB2010/003360 patent/WO2011080576A2/en active Application Filing
  • 2010-12-29 EP EP10830927A patent/EP2519717A2/de not_active Withdrawn

Non-Patent Citations (1)

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