Solar steam generator having a standby heat supply system

Abstract

A standby heat supply system is provided for a solar receiver steam generator to maintain the system at a relatively constant temperature during the nocturnal period when solar radiation is unavailable. An exemplary solar steam generator having a standby heat supply system includes a steam loop having at least one solar panel, a steam drum and circulating pump, whereby solar energy heats the water to generate steam which is provided to the steam drum. The standby heat supply system includes an external standby heater wherein the water from the steam drum is provided to the external standby heater. A heat isolation valve is actuated during the nocturnal period to allow the water to circulate through the standby heater. Another exemplary embodiment of a solar steam generator includes an internal standby heat supply system having heater elements immersed in the steam drum for direct heating of the water during nocturnal periods.

1 . A solar steam generator comprising:
 a solar panel that heats fluid passing therethrough;   a steam drum that separates steam and fluid received from the solar panel; the steam drum providing the fluid to the solar panel;   a standby heat supply system that heats the fluid in the steam drum during periods of low solar energy provided to the solar panel.   
     
     
         2 . The solar steam generator of  claim 1 , wherein the standby heat supply system includes is external to the steam drum. 
     
     
         3 . The solar steam generator of  claim 2 , wherein the standby heat supply system includes a standby heater comprising a vessel having heating elements disposed therein. 
     
     
         4 . The solar steam generator of  claim 2 , wherein the standby heat supply system includes a standby heater comprising a vessel having a heat exchanger disposed therein. 
     
     
         5 . The solar steam generator of  claim 1 , wherein the standby heat supply system includes a valve for providing fluid from the steam drum to the standby heat supply during periods of low solar energy. 
     
     
         6 . The solar steam generator of  claim 1 , wherein the standby heat supply system includes a valve for providing fluid from the steam drum to the standby heat supply in response to a drop in temperature of the fluid. 
     
     
         7 . The solar steam generator of  claim 1 , wherein the standby heat supply system includes a valve for providing fluid from the steam drum to the standby heat supply in response to desired time of day. 
     
     
         8 . The solar steam generator of  claim 1 , wherein the standby heat supply system is internal to the steam drum. 
     
     
         9 . The solar steam generator of  claim 8 , wherein the standby heat supply system includes a standby heater comprising heating elements disposed in the steam drum. 
     
     
         10 . The solar steam generator of  claim 9 , wherein the heating elements are electric heating elements and/or heat exchange tubing. 
     
     
         11 . A method of maintaining a fluid within a solar steam generator at a desired temperature during a nocturnal period, the method comprising:
 heating a fluid flowing through a solar panel with radiant heat;   circulating the heated fluid to a steam drum that separates the steam and fluid received from the solar panel;   circulating the fluid from the steam drum back to the solar panel;   circulating the flow of the fluid to a standby heater when the temperature of the fluid drops below a desired temperature; and   circulating the heated fluid flow from the standby heater back to the steam drum.