Low-Temperature Power Plant and Process for Operating a Thermodynamic Cycle

Abstract

The invention concerns a mechanism for operating a thermodynamic cycle, particularly a low-temperature power plant, as well as a related process, whereby a low-temperature mass stream ( 1 ) feeds a first heat stream to a working fluid ( 6 ) circulating in a first cycle at an initial temperature level (T 1 ), whereby subsequent to an expansion of the working fluid in an expansion machine ( 7 ) a second heat stream is extracted from the working fluid ( 6 ) at a lower expansion temperature level (T 5 ) with respect to the initial temperature level (T 1 ) for an improvement of the energy exploitation of the thermodynamic cycle or the low temperature power plant, which is pumped to a higher pump temperature level and is fed to the low temperature mass stream ( 1 ) and/or fed at least partially to the first cycle.

1 . Thermodynamic machine, particularly a low-temperature power plant, with at least one first cycle ( 20 ) for circulating a working fluid, whereby the first cycle ( 20 ) has at least one expansion machine ( 7 ) and at least one heat exchanger ( 24 ;  27 ) for feeding a first heat stream from a low-temperature mass stream ( 1 ) into the first cycle ( 20 ), whereby a first heat transformer ( 21 ;  26 ) is provided in heat stream connection with the first cycle ( 20 ), with a colder side ( 23 ) downstream of the expansion machine ( 7 ), and has a heat stream connection with a warmer side ( 22 ) with the low-temperature mass stream ( 1 ) or the first cycle ( 20 ). 
   
   
       2 . Thermodynamic machine according to  claim 1  further comprising a second cycle ( 25 ), particularly an ORC cycle, with a second heat transformer ( 26 ), which is located in the same way as the first heat transformer ( 21 ), sequentially to the first cycle ( 20 ), whereby the first ( 21 ) and the second heat transformer ( 26 ) respectively have a heat stream connection with the low-temperature mass stream ( 1 ) between the first ( 20 ) and the second cycle ( 25 ) with their warmer side ( 22 ). 
   
   
       3 . Thermodynamic machine according to  claim 1  further comprising a second cycle ( 25 ) that is fed by a branch stream ( 28 ) by the low-temperature mass stream ( 1 ) downstream of the first cycle ( 20 ), whereby the first heat transformer ( 21 ) with its warmer end ( 22 ) has a heat stream connection with the branch stream ( 28 ) upstream of the second cycle ( 25 ), and whereby a downstream feedback of the branch stream ( 28 ) is provided downstream of the second cycle ( 25 ) into the low-temperature mass stream ( 1 ). 
   
   
       4 . Thermodynamic machine according to  claim 1  further comprising a second cycle ( 25 ) that has a downstream feedback ( 29   a ) to an inlet ( 29   b ), which has a heat stream connection with the warmer end ( 22 ) of the first heat transformer ( 21 ). 
   
   
       5 . Thermodynamic machine according to  claim 1  further comprising at least one recirculation line ( 30 ) provided for feedback of a branch stream ( 28 ) of the low-temperature mass stream ( 1 ) downstream of the first cycle ( 20 ), whereby the warm side ( 22 ) of the first heat transformer ( 21 ) has a heat stream connection with the branch stream ( 28 ). 
   
   
       6 . Thermodynamic machine according to  claim 1  wherein the warm side ( 22 ) of the first heat transformer ( 21 ) in a section between a vaporizer ( 5 ) and expansion machine ( 7 ) has a heat stream connection with the first cycle ( 20 ). 
   
   
       7 . Process for operating a thermodynamic cycle, particularly in a low-temperature power plant according to  claim 1 , with at least one cycle ( 20 ,  25 ), in which a working fluid ( 6 ) circulates, to which a first heat stream is fed by a low-temperature mass stream ( 1 ) at an initial temperature level, whereby after an expansion of the working fluid ( 6 ) in an expansion machine ( 7 ) releasing mechanical energy a second heat stream is extracted from the working fluid ( 6 ) at an expansion temperature level that is lower compared to the initial temperature level wherein the second heat stream in at least one heat transformer ( 21 ,  26 ) is pumped to a pump temperature level which is higher or equal to the initial temperature level and is at least partially fed back to low-temperature mass stream ( 1 ) and/or the at least one cycle ( 20 ,  25 ). 
   
   
       8 . Process according to  claim 7  wherein the second heat stream, which is raised to the pump temperature level, increases a temperature of the low-temperature mass stream ( 1 ) and/or a temperature of the working fluid ( 6 ) in the at least one cycle ( 20 ,  25 ). 
   
   
       9 . Process according to  claim 7  wherein the low-temperature mass stream ( 1 ) is increased by a partial feedback of a low-temperature mass stream outflow ( 29 ) that is heated by the second heat stream. 
   
   
       10 . Process according to  claim 7 , wherein at least one cycle ( 20 ,  25 ) is operated as an organic Rankine cycle (ORC). 
   
   
       11 . Process according to  claim 7  wherein the at least one cycle ( 20 ,  25 ) is operated as a Kalina cycle. 
   
   
       12 . Process according to  claim 7  wherein at least two cycles, particularly two ORC cycles ( 20 ;  25 ), are sequentially fed by the low-temperature mass stream ( 1 ), whereby a feedback into the low-temperature mass stream ( 1 ) of the second heat streams of the cycles that is pumped to the respective pump temperature level takes place between the first cycle ( 20 ) and the second cycle ( 25 ). 
   
   
       13 . Process according to  claim 7  wherein at least two cycles ( 20 ,  25 ), particularly two ORC cycles, are provided, whereby from the low-temperature mass stream ( 1 ) downstream of the first cycle ( 20 ) a branch stream ( 28 ) for feeding a second cycle ( 25 ) is branched off, which downstream of the second cycle ( 25 ), is reunited downstream with the low-temperature mass stream ( 1 ), whereby the second heat stream that is pumped to the pump temperature level of the first cycle ( 20 ) is fed to the branch stream ( 29 ). 
   
   
       14 . Process according to  claim 7  wherein at least two cycles ( 20 ,  25 ), particularly two ORC cycles are provided, whereby the second heat stream of the first cycle ( 20 ) that is pumped to the pump temperature level is fed to an outflow of the second cycle ( 25 ), which is fed again to the second cycle ( 25 ) as inflow. 
   
   
       15 . Process according to  claim 7  wherein a branch stream ( 28 ) is branched off from the low-temperature mass stream ( 1 ) downstream of a cycle ( 20 ), which is heated by the second heat stream to the pump temperature level and is fed to the low-temperature mass stream ( 1 ) upstream of the cycle ( 20 ). 
   
   
       16 . Process according to  claim 15  wherein the branch stream ( 28 ) is dimensioned in such a way, that its pump temperature level prior to recirculation corresponds to the initial temperature level of the low-temperature mass stream ( 1 ). 
   
   
       17 . Process according to  claim 7  wherein the second heat stream is extracted downstream of the expansion machine ( 7 ) and after being pumped to the pump temperature level, is fed back into the cycle ( 20 ), particularly directly before the expansion machine ( 7 ). 
   
   
       18 . Process according to  claim 7  wherein a temperature of a heat transformer fluid is heated by the second heat stream and raised by at least two ejector-adsorbers to or above the pump temperature level to pump the second heat stream to the pump temperature level. 
   
   
       19 . Process according to  claim 7  wherein a heat transformer fluid heated by a second heat stream is at least essentially adiabatically compressed and thereby heated to or above the higher pump temperature level to pump the second heat stream to pump temperature level. 
   
   
       20 . Thermodynamic machine, according to  claim 1 , with the at least one heat transformer ( 21 ;  26 ) being configured such that from a first mass stream with a first temperature level a second mass stream with a second temperature level is produced with the second mass stream being equal or less than the first mass stream and with the second temperature level being higher than the first temperature level.