Method for operating a solar thermal power plant, and solar thermal power plant

Abstract

A method for operating a solar thermal power plant comprising multiple solar radiation receivers operated using a molten salt as the heat transfer medium, wherein each solar radiation receiver comprises a reflector device and an absorber tube, includes: preheating of the absorber tubes, in the state in which said tubes are empty of the molten salt, to a temperature T by concentrating solar radiation on the absorber tubes by means of the reflector devices, wherein the temperature T is greater than or equal to the melting temperature of the salt; after reaching the temperature T: introduction of the molten salt into the absorber tubes and recirculated conduction of the molten salt through the absorber tubes while simultaneously repositioning the reflector devices depending on the position of the sun; on ending the operation: release of the molten salt out of the absorber tubes.

1 - 19 . (canceled) 
     
     
         20 . A method for operating a solar thermal power plant comprising a plurality of solar radiation receivers operated using a molten salt as the heat transfer medium, wherein each solar radiation receiver has a reflector device and an absorber pipe, the method comprising the following steps:
 preheating in a state emptied of molten salt, the absorber pipes to a temperature T by concentrating solar radiation on the absorber pipes by means of the reflector devices, wherein the temperature T is higher than or equal to the melting temperature of the salt;   introducing the molten salt into the absorber pipes and conveying the molten salt through the absorber pipes in a recirculating manner, while at the same time adjusting the reflector devices according to the position of the sun;   discharging the molten salt from the absorber pipes.   
     
     
         21 . Method of  claim 20 , wherein the reflector devices are defocused when operation is ended. 
     
     
         22 . Method of  claim 20 , wherein when preheating the absorber pipes, a power control of the reflector devices is performed in dependence on the position of the sun and the weather conditions. 
     
     
         23 . Method of  claim 20 , wherein discharging the molten salt from the absorber pipes is effected at least in part due to gravity. 
     
     
         24 . Method of  claim 20 , wherein a secondary heat transfer medium, preferably an inert gas, preferably nitrogen, is fed through the absorber pipes, preferably in a recirculating manner, during the preheating of the absorber pipes. 
     
     
         25 . Method of  claim 24 , wherein for discharging the molten salt from the absorber pipes, the secondary heat transfer medium is introduced into the absorber pipes at a pressure higher than ambient pressure, wherein the secondary heat transfer medium presses the molten salt out of the absorber pipes. 
     
     
         26 . Method of  claim 20 , wherein when discharging the molten salt from the absorber pipes, the molten salt is at least in part pumped out of the absorber pipes. 
     
     
         27 . Method of  claim 22 , wherein during the preheating of the absorber pipes, the reflector devices are focused only partly on the absorber pipes or are periodically focused and defocused. 
     
     
         28 . Method of  claim 20 , wherein when being discharged from the absorber pipes, the molten salt is conducted into at least one thermally insulated storage tank. 
     
     
         29 . Method of  claim 20 , wherein when the molten salt is introduced into the absorber pipes, the secondary heat transfer medium is conducted into at least one secondary storage tank. 
     
     
         30 . Method of  claim 25 , wherein the secondary heat transfer medium remains in the absorber pipes when the power plant is not in operation. 
     
     
         31 . Solar thermal power plant for operation using a molten salt as the heat transfer medium and comprising:
 a plurality of solar radiation receivers, each having a reflector device and an absorber pipe through which the heat transfer medium can be conducted,   wherein the absorber pipes are arranged with a gradient in the direction of the at least one storage tank for the molten salt.   
     
     
         32 . Solar thermal power plant of  claim 31 , wherein the absorber pipes of a plurality of reflector devices are connected to form an absorber pipe chain and form a continuous gradient. 
     
     
         33 . Solar thermal power plant of  claim 31 , wherein a supply line for a secondary heat transfer medium opens into an upper end of an absorber pipe or an absorber pipe chain. 
     
     
         34 . Solar thermal power plant of  claim 32 , wherein the solar radiation receivers are arranged in loops, wherein each respective loop is formed by two parallelly arranged absorber pipe chains with the associated reflector devices, and wherein a transverse connection connects the upper ends of the absorber pipe chains. 
     
     
         35 . Solar thermal power plant of  claim 34 , wherein the supply line for a secondary heat transfer medium opens into the transverse connection. 
     
     
         36 . Solar thermal power plant of  claim 33 , wherein by at least one secondary storage tank for the secondary heat transfer medium. 
     
     
         37 . Solar thermal power plant of  claim 36 , wherein the at least one secondary storage tank is formed by at least one storage tank for the molten salt. 
     
     
         38 . Solar thermal power plant of  claim 33 , wherein a pump or a compressor may be arranged in the supply line for the secondary heat transfer medium, by means of which the secondary heat transfer medium can be introduced into an absorber pipe or an absorber pipe chain at a pressure higher than ambient pressure