Generation of steam from solar energy

Abstract

A cavity-type solar energy receiver for generating high pressure steam, which includes panels of tubes defining a cavity within an outer enclosure. Concentrated solar energy provided by a heliostat enters the cavity opening in the enclosure and evaporates water within some of the tube panels. The evaporating tubes receive hot water from a steam drum by natural circulation and return a mixture of steam and hot water to the steam drum. Additional tube panels are positioned to receive reflected solar energy, which is used to preheat feed water and to superheat steam.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of priority of U.S. Provisional Applications 61 / 212,390 filed Apr. 10, 2009 and 61 / 217,425 filed May 29, 2009 and incorporated herein by reference.BACKGROUND OF THE INVENTION:[0002]This invention relates to recovering solar energy in the form of steam, which may be used to generate electricity or in industrial processes. More particularly, the invention includes a novel method and apparatus for converting solar energy to high pressure steam; that is, a steam boiler that employs the sun's rays to produce steam.[0003]Many proposals have been made to focus the sun's rays to concentrate solar energy. Electricity can be made directly by using heat engines that receive heat from focusing the sun's rays with a solar dish. Generating electricity with hot heat transfer liquids has been demonstrated for some years. Parabolic trough systems focus the sun's rays on receiving tubes running through the trough that ca...

AI Technical Summary

Benefits of technology

[0008]In a preferred embodiment, two of the cavity-type solar energy receivers are positioned as mirror images, one facing north and the other south, both receiving concentrated solar energy from mirrors at ground level (a heliostat) reflecting light to the solar energy receivers mounted on a tower. A steam drum serving both receivers is mounted between them and within an enclosure for both receivers. In combination, the panels of tubes form a cavity within which concentrated solar energy is used to generate high pressure steam. Between the cavity formed by panels of tubes and the surrounding enclosure refractory insulation is provided to limit heat losses and to protect the outer enclosure. The solar energy receiver(s) has evaporator tubes mounted opposite the solar energy opening and against adjacent side walls. Economizer tubes for preheating boiler feed water may be included which, if used, could be positioned on the side walls and / or floor of the receiver adjacent the solar energy opening. Superheater tubes are positioned as a roof at the top of the cavity adjacent the evaporator tubes. Auxiliary superheater tubes may be added on the side walls as desired in some embodiments.

Problems solved by technology

However, in applying solar energy only radiant heat is available, which must be transferred to the boiler tubes to generate steam.

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