Solar thermal power system

Abstract

A solar thermal power system includes a solar receiver, and a thermal energy storage arrangement having thermal energy storage fluid to be circulated through the solar receiver to store thermal energy. The system includes a multistage steam turbine operable on variable pressure steam generated by a steam generator arrangement, by utilizing the thermal energy storage fluid. The arrangement includes an economizer section, an evaporator section, and a superheater section communicably configured to utilize the heat of the hot thermal energy storage fluid to generate and supply the variable pressure steam to the turbine. The system includes a recirculation line configured around the economizer section to recirculate the heated water to an inlet of the economizer section, increasing pressure range of the variable pressure steam in the arrangement.

What is claimed is: 
     
         1 . A solar thermal power system, comprising:
 a solar receiver;   a thermal energy storage arrangement including a thermal energy storage fluid to be circulated through the solar receiver to store thermal energy;   a multistage steam turbine configured to be operable on variable pressure steam generated from water supplied from a feedwater supply via the thermal energy storage fluid;   a steam generator arrangement comprising an economizer section, an evaporator section and a superheater section communicably configured to utilize the heat of the hot thermal energy storage fluid at an entrance of the evaporator section to generate and supply the variable pressure steam to the superheater section and eventually to the multistage steam turbine; and   a recirculation line configured around the economizer section to recirculate the heated water to an inlet of the economizer section to increase heat load on the economizer section in turn increasing pressure range of the variable pressure steam in the steam generator arrangement, while maintaining the temperature of the thermal energy storage fluid at an inlet of the evaporator section and at an outlet of the economizer section, and the feedwater temperature to the economizer section at desired values.   
     
     
         2 . The solar thermal power system as claimed in  claim 1 , wherein the recirculation line is configured from the outlet of the economizer section to the inlet of the economizer section. 
     
     
         3 . The solar thermal power system as claimed in  claim 1 , wherein the recirculation line is configured from the evaporator section to the inlet of the economizer section. 
     
     
         4 . The solar thermal power system as claimed in  claim 1 , wherein the evaporator section comprises a steam drum, and in that the recirculation line is configured from the steam drum to the inlet of the economizer section. 
     
     
         5 . The solar thermal power system as claimed in  claim 1  further comprising a bypass line configured to bypass the economizer section to supply the water from the feedwater supply directly to the evaporator section. 
     
     
         6 . The solar thermal power system as claimed in  claim 1  further comprising a reheat assembly configured to the steam generator arrangement to reheat the steam. 
     
     
         7 . The solar thermal power system as claimed in  claim 1 , wherein the thermal energy storage arrangement comprises:
 a first storage tank to store the hot thermal energy storage fluid; and   a second storage tank to store the cold thermal energy storage fluid, the thermal energy storage arrangement supplies the cold thermal energy storage fluid from the second storage tank to the solar receiver to be reheated.