Method for generating energy by means of thermal cycles with high pressure and moderate temperature steam
View Patent ↗The invention relates to a method for generating energy by means of thermal cycles with high pressure and moderate temperature steam, which allows improving the energy and operational efficiency of the conversion of heat energy into mechanical or electrical energy by means of thermal cycles in which the temperature of the steam is limited to moderate values in its generation, comprising the following steps: a) generating steam at a pressure above 65 bar and a moderate temperature below 400° C., b) expanding said steam in a steam turbine, steam of an intermediate pressure, comprised between 10-40 bar, with a moderate moisture, below 15%, being obtained c) drying said steam by means of a moisture separator and reheating said steam, d) expanding said steam in the turbine, and e) heating boiler water used to generate the steam by means of a plurality of steam extractions from the turbine, in order to exchange heat with said boiler water.
1. Method for generating energy using thermal cycles with high pressure and moderate temperature steam, the method comprising the steps of:
a) generating superheated steam at a pressure above 65 bar and a moderate temperature below 400° C. in a waste boiler, the waste boiler comprising waste or biomass as an energy source,
b) expanding the superheated steam generated in step a) directly in at least one two-body steam turbine comprising a high pressure body and a low pressure body, steam of an intermediate pressure, comprised between 10-40 bar, with a moderate moisture, below 15%, being obtained in said high pressure body,
c) drying the steam obtained in step b) using at least one moisture separator and reheating said steam with a hot fluid different from steam, whereas the hot liquid water, collected in the moisture separator, is used to supply heat to fluids of the process with a lower thermal level,
d) expanding the steam obtained in step c) in the low pressure body of said at least one turbine, and
e) heating boiler water used to generate the steam in step a) using a plurality of steam extractions from said at least one turbine in order to exchange heat with said boiler water.
2. Method for generating energy using thermal cycles with high pressure and moderate temperature steam according to claim 1 , wherein the steam obtained in step b) has a pressure comprised between 15-30 bar and a moisture below 5%, and in step e) the boiler water is heated using at least 4 steam extractions from said at least one turbine.
3. Method for generating energy using thermal cycles with high pressure and moderate temperature steam according to claim 1 , wherein step e) further comprises using at least one pump for impelling the boiler water, said pump being coupled to a shaft of said at least one steam turbine.
4. Method for generating energy using thermal cycles with high pressure and moderate temperature steam according to claim 1 , wherein the generation of steam in step a) and the reheating of dry steam in step c) comprises using heat obtainable from combustion gases of matter selected from waste, biomasses, and a mixture thereof.
5. Method for generating energy using thermal cycles with high pressure and moderate temperature steam according to claim 4 , wherein step c) further comprises using air in the combustion of the matter selected from waste, biomasses, and a mixture thereof, wherein said air is preheated using boiler feedwater and water extracted from said at least one moisture separator used in said step c).
6. Method for generating energy using thermal cycles with high pressure and moderate temperature steam according to claim 4 , wherein the combustion of matter selected from waste, biomasses, and a mixture thereof is performed in at least one furnace in the cleaning of which superheated steam is used, obtained using the following steps:
f) taking part of the steam generated in step a) and reducing its pressure, using at least one reducing valve, to a sufficient pressure level for overcoming pressure drops of a system comprising a plurality of soot blowers, and
g) heating the steam obtained in step f) in at least one heat exchanger, in which a heating fluid is part of the steam generated in step a), superheated steam configured to operate the soot blowers being obtained.
7. Method for generating energy using thermal cycles with high pressure and moderate temperature steam according to claim 1 , wherein the generation of steam in step a) and the reheating of dry steam in step c) comprises using heat of a solar origin.
8. Method for generating energy using thermal cycles with high pressure and moderate temperature steam according to claim 1 , additionally comprising the following steps:
h) superheating the steam generated in step a) using heat from the combustion of an auxiliary fuel to a high temperature comprised between 500-580° C., prior to step b), and
i) performing the reheating of step c) using reheating the steam obtained in step b) using heat from the combustion of said auxiliary fuel at a high temperature comprised between 500-580° C.
9. Method for generating energy using thermal cycles with high pressure and moderate temperature steam according to claim 8 , wherein the auxiliary fuel is matter selected from biomass, biogas, natural gas, synthesis gas, waste, waste processing rejects, petroleum-derived fuels, and a mixture thereof.