Method for gas removal from high-temperature heat-transfer fluids in solar thermal power plants

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Solution Overview

Problem

Existing solar thermal power plants face challenges in efficiently removing gaseous decomposition products like H2, CH4, and C2H6 from high-temperature heat transfer fluids, requiring frequent fluid replacement and additional treatment plants, which are costly and energy-intensive.

Innovation Solution

A method utilizing an expansion tank and a drainage tank with pressure and fill level controls, where the daily volume change of the heat transfer fluid is used to separate gaseous decomposition products by transferring part of the volume to the drainage tank at lower pressure, allowing for condensation and recirculation of low-boiling components, with inert gas filling to prevent phase separation and cavitation, and minimizing inert gas consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If external treatment plants with multiple columns are used to remove gaseous decomposition products, then separation effectiveness is improved, but device complexity and investment costs increase

Engineering Contradiction:
Improveseparation effectivenessVSAvoidtreatment plant structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts the gas separation function from complex multi-column treatment plants and implements it through a simple drainage tank where gaseous decomposition products naturally separate from the heat transfer fluid due to density differences and pressure reduction, achieving effective separation without complex equipment

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The system uses the natural daily volume changes of the heat transfer fluid in the solar field and the inherent gas-liquid separation properties to automatically remove gaseous decomposition products through the drainage tank, without requiring external treatment plants or additional energy input for degassing

Inventive Principle:
Principle #25Self-service

2Reliability

If heat transfer fluid is frequently replaced to remove decomposition products, then fluid purity is improved, but loss of substance and operational downtime increase

Engineering Contradiction:
Improvefluid purityVSAvoidheat transfer fluid loss
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The invention enables continuous in-situ removal of gaseous decomposition products from the heat transfer fluid through the drainage tank during normal operation, maintaining fluid purity without interruption to power plant operation and eliminating the need for fluid replacement

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The system selectively removes only the gaseous decomposition products from the heat transfer fluid while retaining and recirculating the valuable heat transfer fluid itself, preventing fluid loss and avoiding the costs associated with fluid replacement

Inventive Principle:
Principle #34Discarding and recovering

3Reliability

If additional treatment plants are installed for gas removal, then separation capability is improved, but energy consumption increases

Engineering Contradiction:
Improvegas removal capabilityVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The drainage tank utilizes the natural daily volume expansion and contraction of the heat transfer fluid in the solar field to automatically transfer fluid containing gaseous decomposition products to the drainage tank, where gas separation occurs passively without requiring external energy input for pumping or heating

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system exploits the phase transition of gaseous decomposition products from dissolved state in the hot heat transfer fluid to gas phase upon pressure reduction in the drainage tank, enabling natural gas separation without additional energy input

Inventive Principle:
Principle #36Phase transitions

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This method allows for continuous, efficient removal of gaseous decomposition products without additional treatment plants, reducing investment and energy costs, and ensures the recirculation of low-boiling components, thereby maintaining the power plant's operation with minimal energy consumption and no auxiliary thermal energy required for degassing.

Implementation Method 1

the volume of the HTF in the solar field expands

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

the volume of the HTF in the solar field contracts

Methodology Applied
Scientific EffectThermal contraction: Thermal Contraction

Implementation Method 3

part of the additional volume of the HTF is transferred to a drainage tank operated with lower pressure, in which gaseous decomposition products and light-boiling components escape from the HTF

Methodology Applied
Scientific EffectPressure reduction separation: Depressurisation

Implementation Method 4

the low-boiling components are condensed

Methodology Applied
Scientific EffectCondensation: Condensation

Data Source

PatentEP3475566B1Method for gas removal from high-temperature heat-transfer fluids in solar thermal power plants
Publication Date: 2020.01.29 WACKER CHEMIE AG
  • EP3475566B1 patent drawingFigure 1
  • EP3475566B1 patent drawingFigure 2

AI summary

The invention relates to a method for removing gaseous decomposition products from the high-temperature heat-transfer fluid HTF of an operating solar thermal power plant having an HTF circuit, wherein a volume increase of the HTF in the HTF circuit occurs regularly in the day-night cycle, which volume increase is caused by solar irradiation in a solar array through which HTF flows and by the heating caused thereby during the day, and the additional volume formed by the volume increase is collected from the HTF circuit into an expansion container, some of the additional volume of the HTF is transferred into a drainage container operated at lower pressure, in which gaseous decomposition products and low-boiling constituents escape from the HTF, the low-boiling constituents being condensed, and, in the event of volume contraction of the HTF occurring during the nightly cooling, some of the additional volume of the HTF is returned from the drainage container into the expansion container and from the expansion container into the HTF circuit, the volumes in the expansion container and in the drainage container freed by the transfers of the HTF being filled up with inert gas.