Method and device for generating electrical energy

Abstract

The invention relates to a combined system for generating electrical energy consisting of a power plant and an air handling system. The power plant comprises a first gas expansion unit connected to a generator. The air handling system comprises an air compression unit, a heat exchange system, and a fluid tank. In a first operating mode, feed air is compressed in the air compression unit and cooled in the heat exchange system against a first and a second coolant. A storage fluid is generated and stored as cryogenic fluid in the fluid tank. In a second operating mode, cryogenic fluid is removed from the fluid tank, vaporized, or pseudo-vaporized, at superatmospheric pressure, and heated in the heat exchange system against the second and first coolants.

1 . A method for generating electrical energy in a combined system made up of a power plant and an air treatment plant, wherein the power plant has a first gas expansion unit ( 300 ), which is connected to a generator for generating electrical energy, and the air treatment plant has an air compression unit ( 2 ), a heat exchanger system ( 21 ) and a liquid tank ( 200 ), and wherein in a first operating mode
 in the air treatment plant   feed air is compressed in the air compression unit ( 2 ) and cooled in the heat exchanger system ( 21 ),   a storage fluid is produced from the compressed and cooled feed air,   the storage fluid is stored as a cryogenic liquid ( 101 ) in the liquid tank ( 200 ),   a stream of a first refrigeration transfer medium is introduced in the liquid state into the heat exchanger system ( 21 ), where it is warmed from a first temperature level T 1  to a second temperature level T 2 , and   a stream of a second liquid refrigeration transfer medium is introduced in the liquid state into the heat exchanger system ( 21 ), where it is warmed from a third temperature level T 3  to a fourth temperature level T 4 ,   
       and in a second operating mode
 cryogenic liquid ( 103 ) is taken from the liquid tank ( 200 ) and vaporized or pseudo-vaporized and warmed as a high-pressure stream in the heat exchanger system ( 21 ) in indirect heat exchange, and the gaseous high-pressure storage fluid ( 104 ) generated in the process is expanded in the gas expansion unit ( 300 ), 
 a stream of the first refrigeration transfer medium is introduced in the liquid state into the heat exchanger system ( 21 ), where it is cooled from the second temperature level T 2  to the first temperature level T 1 , and 
 a stream of the second liquid refrigeration transfer medium is introduced in the liquid state into the heat exchanger system ( 21 ), where it is cooled from the fourth temperature level T 4  to the third temperature level T 3 , and 
 the (pseudo-)vaporization of the cryogenic liquid ( 103 ) is carried out, characterized in that, 
 
       in the first operating mode, the feed air compressed in the air compression unit ( 2 ) passes into indirect heat exchange with the first liquid refrigeration transfer medium and with the second liquid refrigeration transfer medium at the same pressure in the heat exchanger system ( 21 ). 
     
     
         2 . The method as claimed in  claim 1 , characterized in that the warming of the first refrigeration transfer medium in the first operating mode and the cooling of the first refrigeration transfer medium in the second operating mode are carried out in the same groups of passages of the heat exchanger system ( 21 ). 
     
     
         3 . The method as claimed in  claim 1 , characterized in that the warming of the second refrigeration transfer medium in the first operating mode and the cooling of the second refrigeration transfer medium in the second operating mode are carried out in the same groups of passages of the heat exchanger system ( 21 ). 
     
     
         4 . The method as claimed in  claim 1 , characterized in that the first temperature level is lower than the fourth temperature level, in particular is more than 18 K lower. 
     
     
         5 . The method as claimed in  claim 1 , characterized in that feed air is also compressed in the air compression unit ( 2 ) in the second operating mode.) 
     
     
         6 . The method as claimed in  claim 1  characterized in that the power plant has a gas turbine system with a combustion chamber, a gas turbine expander and a generator, and at least some of the gaseous high-pressure storage fluid ( 104 ) is expanded in the gas turbine expander of a gas turbine system, the storage fluid ( 104 ) being fed to the gas turbine system downstream of the (pseudo-)vaporization ( 21 ). 
     
     
         7 . The method as claimed in  claim 1 , characterized in that the gas expansion unit has a hot-gas turbine system having at least one heater and a hot-gas turbine. 
     
     
         8 . The method as claimed in  claim 6 , characterized in that the gaseous high-pressure storage fluid is expanded in two steps, the first step being carried out as a work-performing expansion in the hot-gas turbine system and the second step being carried out in the gas turbine system, the gaseous high-pressure storage fluid being fed to the hot-gas turbine system, where it is expanded to an intermediate pressure, and a gaseous intermediate-pressure storage fluid being taken from the hot-gas turbine system and finally being fed to the gas turbine system. 
     
     
         9 . The method as claimed in  claim 1 , characterized in that the air treatment plant ( 2 ) is in the form of a cryogenic air separation plant or of an air liquefaction plant. 
     
     
         10 . The method as claimed in  claim 1 , characterized in that the cryogenic liquid ( 3 ) is formed by liquefied air or liquid nitrogen. 
     
     
         11 . The method as claimed in  claim 1 , characterized in that, in the second operating mode, the high-pressure stream passes into indirect heat exchange with the second liquid refrigeration transfer medium and with the first liquid refrigeration transfer medium at the same superatmospheric pressure in the heat exchanger system ( 21 ). 
     
     
         12 . An apparatus for generating electrical energy having a combined system made up of a power plant and an air treatment plant, wherein the power plant has a first gas expansion unit ( 300 ), which is connected to a generator for generating electrical energy, and the air treatment plant has an air compression unit ( 2 ), a heat exchanger system ( 12 ) and a liquid tank ( 200 ), and wherein the apparatus has a control device and also pipelines and control elements, with the aid of which it can be operated in a first and in a second operating mode, wherein 
       in a first operating mode
 in the air treatment plant 
 feed air is compressed in the air compression unit ( 2 ) and cooled in the heat exchanger system ( 12 ), 
 a storage fluid is produced from the compressed and cooled feed air, 
 the storage fluid is stored as a cryogenic liquid ( 101 ) in the liquid tank ( 200 ), 
 a stream of a first refrigeration transfer medium is introduced in the liquid state into the heat exchanger system ( 21 ), where it is warmed from a first temperature level T 1  to a second temperature level T 2 , and 
 a stream of a second liquid refrigeration transfer medium is introduced in the liquid state into the heat exchanger system ( 21 ), where it is warmed from a third temperature level T 3  to a fourth temperature level T 4 , and in a second operating mode 
 cryogenic liquid ( 103 ) is taken from the liquid tank ( 200 ) and vaporized or pseudo-vaporized as a high-pressure stream in the heat exchanger system ( 21 ) at superatmospheric pressure, and the gaseous high-pressure storage fluid ( 104 ) generated in the process is expanded in the gas expansion unit ( 300 ), 
 a stream of the first refrigeration transfer medium is introduced in the liquid state into the heat exchanger system ( 21 ), where it is cooled from the second temperature level T 2  to the first temperature level T 1 , and 
 a stream of the second liquid refrigeration transfer medium is introduced in the liquid state into the heat exchanger system ( 21 ), where it is cooled from the fourth temperature level T 4  to the third temperature level T 3 , 
 characterized in that 
 the control device and also the pipelines and the control elements are formed in such a way that, in the first operating mode, the feed air compressed in the air compression unit ( 2 ) passes into indirect heat exchange with the first liquid refrigeration transfer medium and with the second liquid refrigeration transfer medium at the same pressure in the heat exchanger system ( 21 ).