Direct solar steam generator and method of shuting down a direct solar steam generator

Abstract

A direct solar steam generator is provided. The direct solar steam generator includes a solar evaporator having an evaporator circuit for circulation of a working fluid, an evaporator inlet pipe for supplying fluid to the evaporator circuit and an evaporator outlet pipe for collecting the working fluid exiting the evaporator circuit, and a solar concentrator for concentrating solar energy towards the evaporator circuit. The direct solar steam generator also includes a fluid arrangement configured to allow forming a static liquid seal in the outlet pipe using the working fluid.

Description

[0001]The present invention relates to a direct solar steam generator, of the type comprising a solar evaporator having an evaporator circuit for circulation of a working fluid, an evaporator inlet pipe for supplying fluid to the evaporator circuit and an evaporator outlet pipe for collecting the working fluid exiting the evaporator circuit, and a solar concentrator for concentrating solar energy towards the evaporator circuit.[0002]During operation of the direct solar steam generator, the solar concentrator concentrates solar energy onto the evaporator, a working fluid in liquid state is fed to the inlet of the evaporator thus vaporizing at least part of the working fluid using the solar energy, and the steam is collected at the outlet of the evaporator. Steam outlets the evaporator at a high positive pressure that is a pressure higher than the atmospheric pressure.[0003]During shutdown of the steam generator, e.g. overnight, the inlet and outlet of the evaporator are closed to flu...

AI Technical Summary

Benefits of technology

The invention proposes a direct solar steam generator that is cost-effective and simple to use, while also preventing air from entering efficiently.

Problems solved by technology

Steam in the evaporator tends to cool down thus resulting in liquefaction of at least part of the working fluid.

This in turn results in a pressure drop in the evaporator down to a negative pressure that is a pressure inferior to the atmospheric pressure.

Negative pressure in the evaporator raises the risk of air ingress into the evaporator due to leaks on flow control valves controlling fluid flow at inlet and outlet of the evaporator.

Air ingress into the fluid circuit may have negative consequences on the efficiency and reliability of the solar steam generator.

This however results in significant energy losses and fluid accumulation in the steam generator.

This however requires the expensive of the nitrogen generation system and necessitates eliminating the nitrogen when restarting the system involving blowing out a significant amount of steam and energy.

Further, this may not completely eliminate air ingress.

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