Method for operating a solar-thermal parabolic trough power plant

Abstract

A method for operating an indirectly heated, solar-thermal steam generator and to an indirectly heated, solar-thermal steam generator are provided. A heat transfer medium is used in the solar-thermal steam generator. The supply water mass flow M is predictively controlled by a device for adjusting the supply water mass flow M. To this end, a nominal value Ms is fed to the device. A correction value K T , by which thermal storage effects of stored or withdrawn thermal energy are corrected is taken into account by the nominal value Ms.

1 - 12 . (canceled) 
     
     
         13 . A method for operating an indirectly heated solar-thermal steam generator featuring a heat transfer medium, comprising:
 supplying a desired value {dot over (M)} s  for the feedwater mass flow {dot over (M)} to a device for adjusting the feedwater mass flow {dot over (M)},   wherein a first correction value K T  is taken into account when setting the desired value {dot over (M)} s  for the feedwater mass flow {dot over (M)}, whereby thermal storage effects of thermal energy that is stored or withdrawn relative to the steam generator is corrected.   
     
     
         14 . The method as claimed in  claim 13 , wherein the thermal storage effects of thermal energy that is stored or withdrawn relative to a plurality of tube walls of the solar-thermal steam generator are corrected by means of the first correction value K T . 
     
     
         15 . The method as claimed in  claim 13 , wherein the thermal storage effects of thermal energy that is stored or withdrawn relative to the heat transfer medium are corrected by means of the first correction value K T . 
     
     
         16 . The method as claimed in  claim 13 , wherein a total heat quantity {dot over (Q)} of the solar-thermal steam generator is taken into account when setting the desired value {dot over (M)} s , and is calculated from the product of
 an enthalpy difference between a first enthalpy of the heat transfer medium at an inlet of the solar-thermal steam generator and a second enthalpy of the heat transfer medium at an outlet of the solar-thermal steam generator, and   a measured mass flow of the heat transfer medium ahead of the inlet of the solar-thermal steam generator.   
     
     
         17 . The method as claimed in  claim 13 ,
 wherein a second correction value K F  is also taken into account when setting the desired value {dot over (M)} s , and   wherein the second correction value K F  is used to correct feedwater quantities that are stored or withdrawn relative to a plurality of steam generator tubes of the solar-thermal steam generator.   
     
     
         18 . The method as claimed in  claim 17 , wherein the second correction value K F  is determined using a feedwater inlet overcooling. 
     
     
         19 . The method as claimed in  claim 17 , wherein the second correction value K F  is determined using a feedwater inlet enthalpy. 
     
     
         20 . The method as claimed in  claim 17 , wherein the second correction value K F  is determined using a feedwater temperature. 
     
     
         21 . The method as claimed in  claim 13 , wherein the solar-thermal steam generator is integrated into a solar-thermal parabolic trough power plant featuring a plurality of parabolic troughs, by means of which the heat transfer medium is subjected to solar-thermal heating. 
     
     
         22 . The method as claimed in  claim 13 , wherein the heat transfer medium is selected from the group consisting of thermo-oil, a salt melt and a metal melt. 
     
     
         23 . An indirectly heated solar-thermal steam generator, comprising:
 a heat transfer medium; and   a device for adjusting the feedwater mass flow {dot over (M)},   wherein the device is governed with reference to a desired value {dot over (M)} s  for the feedwater mass flow {dot over (M)}, and   wherein an associated feedwater flow control is so configured as to specify the desired value {dot over (M)} s  by means of the method as claimed in  claim 13 .   
     
     
         24 . The indirectly heated solar-thermal steam generator as claimed in  claim 23 ,
 wherein the solar-thermal steam generator is integrated into a solar-thermal parabolic trough power plant and is connected to a plurality of parabolic troughs for the supply of the superheated heat transfer medium, and   wherein the plurality of parabolic troughs are directly subjected to focused solar incidence.   
     
     
         25 . The indirectly heated solar-thermal steam generator as claimed in  claim 23 , wherein the heat transfer medium is selected from the group consisting of thermo-oil, a salt melt and a metal melt. 
     
     
         26 . A solar-thermal parabolic trough power plant, comprising:
 an indirectly heated solar-thermal steam generator as claimed in  claim 23 .