Molten Salt Tank Layout for Lower-Cost Solar Thermal Storage
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Solution Overview
Problem
The high temperatures reached by molten salts in direct thermal energy storage systems for concentrated solar power plants require expensive, high-temperature resistant materials for storage tanks, leading to increased investment costs and potential material degradation issues.
Innovation Solution
A thermal energy storage system using at least three tanks operating at different temperatures, with the 'hot' tank made of expensive stainless steel and the other tanks made of carbon steel, allowing for efficient thermal energy use and reduced material costs by optimizing temperature ranges for each tank.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature resistant materials are used for storage tanks, then the reliability and temperature resistance are improved, but the investment cost increases
Solution Approach 1:
The storage system is divided into multiple independent tanks (first storage tank, second storage tank, third storage tank) operating at different temperature levels. This segmentation allows each tank to be constructed with materials appropriate for its specific temperature range, rather than requiring all tanks to use expensive high-temperature resistant materials.
Solution Approach 2:
Different material qualities are applied to different tanks based on their operating conditions. The first storage tank (highest temperature) uses high-temperature resistant materials, while the second and third storage tanks (lower temperatures) use cheaper carbon steel materials. This local differentiation of material quality optimizes the balance between reliability and cost.
2Temperature
If high-temperature resistant materials are used for storage tanks, then the temperature resistance is improved, but the material degradation is accelerated
Solution Approach 1:
The storage system is divided into multiple independent tanks (first storage tank, second storage tank, third storage tank) operating at different temperature levels. This segmentation allows each tank to be constructed with materials appropriate for its specific temperature range, rather than requiring all tanks to use expensive high-temperature resistant materials.
Solution Approach 2:
Different material qualities are applied to different tanks based on their operating conditions. The first storage tank (highest temperature) uses high-temperature resistant materials, while the second and third storage tanks (lower temperatures) use cheaper carbon steel materials. This local differentiation of material quality optimizes the balance between reliability and cost.
3Ease of manufacture
If multiple tanks operating at different temperatures are used, then the investment cost is reduced and material lifespan is extended, but the system complexity increases
Solution Approach 1:
The storage system is divided into multiple independent tanks (first storage tank, second storage tank, third storage tank) operating at different temperature levels. This segmentation allows each tank to be constructed with materials appropriate for its specific temperature range, rather than requiring all tanks to use expensive high-temperature resistant materials.
Solution Approach 2:
Multiple storage tanks operating at different temperature levels are combined into a single integrated thermal energy storage system. The tanks work together through the molten salt circuit to provide comprehensive thermal energy storage coverage, merging their individual functions into a unified system that achieves cost savings while maintaining operational efficiency.
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 configuration reduces investment costs and minimizes material degradation by distributing temperature loads across multiple tanks, enhancing the efficiency of thermal energy storage and extending the lifespan of high-temperature materials.
Implementation Method 1
solar energy is captured in a concentrated way by means of mirrors, such as a field of parabolic troughs
Implementation Method 2
the thermal energy recovered from solar radiation during day time, is stored during day time
Implementation Method 3
the molten salts are transferred from the cold tank to the hot one. When the heat is recovered, molten salts flow from the hot tank to the cold tank
Implementation Method 4
This type of system relies on thermal buoyancy to maintain thermal stratification and discrete hot and cold thermal regions inside the tank
Implementation Method 5
Since the density of high temperature molten salts is lower than that of low temperature molten salts, the first volume of high temperature molten salts stratifies on the top of the low temperature molten salts
Implementation Method 6
The thus collected solar thermal energy is used to heat a fluid that serves to produce steam which, in turn, is used to produce electric power by means of a turbine and generator system
Implementation Method 7
used to produce electric power (generally in a conventional Rankine cycle)
Data Source
AI summary
Disclosed is a thermal energy storage system for storing collected solar thermal energy. The system comprises a solar thermal energy collection facility in the form of a field of parabolic troughs, which is in thermal communication with a molten salt circuit. The molten salt circuit is in fluid communication with a molten salt storage facility comprising at least three storage tanks that are each in fluid communication with the molten salt circuit. The multiple tanks set-up allows using cheaper materials, and a more efficient storage of thermal energy.