System for storing and outputting thermal energy having a heat accumulator and a cold accumulator and metho for the operation thereof

Abstract

A system for storing and outputting thermal energy and a method for operating the system are provided. The system has a heat accumulator and a cold accumulator. The heat accumulator and the cold accumulator are discharged in two separate discharging circuits, wherein the thermal energy is converted into electrical energy, for example by a generator. The residual heat from the process in the circuit can be advantageously fed to the process in the circuit by a first heat exchanger, whereby the total efficiency is advantageously improved. Furthermore, the heat from the heat accumulator can be advantageously transferred into the first circuit by a waste-heat steam generator. The heat accumulator and the cold accumulator can be charged, for example, with excess energy from the electric network by a motor. Excess energy reserves of alternative energy resources, for example, can thus be stored.

1 . A plant for storing and releasing thermal energy comprising:
 a heat accumulator and a cold accumulator, wherein the heat accumulator is adapted to release the stored heat to a first line in a discharging circuit for a working medium, and in the discharging circuit the following units are interconnected in the specified sequence by means of the first line:
 a first thermal fluid energy machine operated as a working machine, 
 a release point for heat from the heat accumulator, and 
 a second thermal fluid energy machine operated as a power machine, 
   wherein the cold accumulator is adapted to release the stored cold to a second line, wherein the second line forms a closed circuit in which the following units are interconnected in the specified sequence by the means of the second line:
 a third thermal fluid energy machine which is operated as a working machine, downstream of said release point for the cold stored in the cold accumulator, 
 a heat source, and 
 a fourth thermal fluid energy machine operated as a power machine. 
   
     
     
         2 . The plant as claimed in  claim 1 ,
 wherein the heat source comprises a first heat exchanger which can extract heat from the first line and is arranged between the third fluid energy machine and the fourth fluid energy machine.   
     
     
         3 . The plant as claimed in  claim 2 ,
 wherein the release point for the heat accumulator is formed by a fifth heat exchanger which can feed heat to the first line and which is connected into a circuit formed by a fourth line, wherein in this circuit the following units are interconnected:   the fifth heat exchanger,   a tenth thermal fluid energy machine operated as a working machine, and   the heat accumulator.   
     
     
         4 . The plant as claimed in  claim 3 ,
 wherein the heat source comprises a second heat exchanger which can extract heat from the fourth line and lies downstream of the fifth heat exchanger with regard to the flow direction in the fourth line.   
     
     
         5 . The plant as claimed in  claim 3 ,
 wherein the fifth heat exchanger is formed by a waste heat steam generator.   
     
     
         6 . The plant as claimed in  claim 5 ,
 wherein the fifth heat exchanger and the second thermal fluid energy machine have a plurality of stages.   
     
     
         7 . The plant as claimed in  claim 1 ,
 wherein the release point for the cold stored in the cold accumulator consists of a third heat exchanger which can release heat to the second line and is incorporated into a cooling circuit formed by a third line, wherein in the cooling circuit the following units are interconnected:   the third heat exchanger   a fifth thermal fluid energy machine which is operated as a working machine, and   the cold accumulator.   
     
     
         8 . The plant as claimed in  claim 1 , wherein the second line is filled with ammonia. 
     
     
         9 . The plant as claimed in  claim 1 ,
 wherein provision is made in the second line between the third thermal fluid energy machine and the first heat exchanger for a fourth heat exchanger which enables a heat input from the environment of the plant into the second line.   
     
     
         10 . A method for storing and releasing thermal energy via a heat accumulator and a cold accumulator, the method comprising:
 during the discharging cycle the heat accumulator releasing the stored heat to a first line in a discharging circuit for a working medium and in the discharging circuit working medium passes through the following units in the specified sequence via a first line:
 a first thermal fluid energy machine which is operated as a working machine 
 the release point for heat from the heat accumulator, and 
 a second thermal fluid energy machine which is operated as a power machine, and 
   the cold accumulator releasing the stored cold to a second line, wherein the second line forms a closed circuit in which the working medium passes through the following units in the specified sequence via the second line:
 a third thermal fluid energy machine which is operated as a power machine, downstream of said release point for the cold stored in the cold accumulator, 
 a heat source, and 
 a fourth thermal fluid energy machine which is operated as a power machine. 
   
     
     
         11 . The plant as claimed in  claim 1 ,
 wherein the first thermal fluid energy machine comprises a pump.   
     
     
         12 . The plant as claimed in  claim 1 ,
 wherein the second thermal fluid energy machine comprises a stream turbine.   
     
     
         13 . The plant as claimed in  claim 1 ,
 wherein the third thermal fluid energy machine comprises a pump.   
     
     
         14 . The plant as claimed in  claim 1 ,
 wherein the forth thermal fluid energy machine comprises a stream turbine.   
     
     
         15 . The method as claimed in  claim 10 ,
 wherein the first thermal fluid energy machine comprises a pump.   
     
     
         16 . The method as claimed in  claim 10 ,
 wherein the second thermal fluid energy machine comprises a stream turbine.   
     
     
         17 . The method as claimed in  claim 10 ,
 wherein the third thermal fluid energy machine comprises a pump.   
     
     
         18 . The method as claimed in  claim 10 ,
 wherein the forth thermal fluid energy machine comprises a stream turbine.