Iron Ore Pellet Thermal Storage for High-Temperature Industrial Processes

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Solution Overview

Problem

Current thermal storage systems for industrial processes, such as calcining and steam cycle processes, face challenges in achieving high output temperatures above 900°C, with existing solutions like molten salt and hot rock systems being inefficient and environmentally risky, and lacking scalability for high-temperature applications.

Innovation Solution

A thermal storage system utilizing iron ore pellets as heat storage elements and a gaseous heat transfer fluid, capable of achieving output temperatures up to 1200°C, with iron ore pellets providing high availability, low cost, and low environmental impact, and allowing for scalable solutions up to several hundred thousand cubic meters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If molten salt or hot rock systems are used for thermal storage, then thermal energy can be stored, but the output temperature cannot exceed 900°C and environmental risks increase

Engineering Contradiction:
Improveoutput temperatureVSAvoidenvironmental risk
Core Design Contradiction:
TemperatureVSObject-affected harmful factors

Solution Approach 1:

The patent changes the material parameter from molten salt or hot rock to iron ore pellets, enabling operation at temperatures above 900°C (up to 1200°C) while eliminating the environmental risks associated with molten salt leakage and rock degradation. This material substitution resolves the contradiction by achieving higher temperatures without compromising environmental safety.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs iron ore pellets that can be replaced if needed, providing a cost-effective and environmentally safe alternative to expensive and hazardous molten salt systems. The pellets serve as a disposable or replaceable medium that eliminates long-term environmental liability while achieving the required temperature output.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Temperature

If molten salt systems are used for thermal storage, then thermal energy can be stored, but scalability for high-temperature applications is limited

Engineering Contradiction:
Improveoutput temperatureVSAvoidscalability
Core Design Contradiction:
TemperatureVSAdaptability or versatility

Solution Approach 1:

The patent segments the thermal storage system into numerous individual iron ore pellets that can be independently handled, stored, and replaced. This segmentation enables easy scalability - the system can be expanded by simply adding more pellets to the storage chamber, making it adaptable to various temperature and capacity requirements without the complex constraints of molten salt systems.

Inventive Principle:
Principle #1Segmentation

3Use of energy by stationary object

If conventional thermal storage systems are used, then thermal energy can be stored, but cost efficiency decreases due to material and environmental management costs

Engineering Contradiction:
Improveenergy efficiencyVSAvoidcost efficiency
Core Design Contradiction:
Use of energy by stationary objectVSEase of manufacture

Solution Approach 1:

The patent uses inexpensive iron ore pellets as the thermal storage medium, eliminating the need for expensive molten salt containment systems, heating systems, and environmental protection infrastructure. The pellets are a cheap, readily available material that reduces both capital expenditure and operational costs, thereby improving overall cost efficiency while maintaining energy efficiency.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

4Temperature

If iron ore pellets are used as heat storage elements, then output temperature can reach 1200°C and environmental impact is reduced, but system complexity increases

Engineering Contradiction:
Improveoutput temperatureVSAvoidsystem complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent extracts the thermal storage function from complex molten salt systems and implements it using simple iron ore pellets contained in a basic chamber with heating and storage zones. This extraction simplifies the overall system by removing the need for complex containment structures, thermal management systems, and environmental protection mechanisms, thereby reducing device complexity while achieving higher temperatures with lower environmental impact.

Inventive Principle:
Principle #2Taking out (Extraction)

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

The system enables cost- and energy-efficient storage and supply of thermal energy for industrial processes, reducing dependency on fossil fuels and grid power, while providing flexibility in electricity consumption and enabling grid independence for renewable energy-powered processes.

Implementation Method 1

The heat transfer fluid is allowed to enter the storage container at one of the first and second ends through the at least one first fluid opening or the at least one second fluid opening and flow through the bed of heat storage elements to the opposite end of the storage container. The heat transfer fluid is configured to transfer heat to the heat storage elements in the charging mode

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 2

a bed of heat storage elements arranged inside the storage container, the heat storage elements are in a solid state in the charging mode, the storing mode and the discharging mode... The heat storage elements comprise iron ore pellets

Methodology Applied
Scientific EffectThermal energy storage: Thermal Energy Storage

Implementation Method 3

The heat transfer fluid is configured to transfer heat from the heat storage elements in the discharging mode

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP3922939A1A method for storing thermal energy, a thermal storage system and a use of such a thermal storage system
Publication Date: 2021.12.15 VATTENFALL AB
  • EP3922939A1 patent drawingFigure 1
  • EP3922939A1 patent drawingFigure 2a~2c
  • EP3922939A1 patent drawingFigure 3

AI summary

The invention relates to a thermal storage system (10) for industrial processes. The thermal storage system (10) comprising: a storage container (20) extending longitudinally between a first end (21) and a second end (22), wherein the first end (21) comprises at least one first fluid opening (23) and the second end (22) comprises at least one second fluid opening (24); a bed (35) of heat storage elements (30) arranged inside the storage container (20); and a heat transfer fluid (40), wherein the heat transfer fluid (40) is configured to transfer heat to the heat storage elements (30) in a charging mode and from the heat storage elements (30) in a discharging mode. The heat storage elements (30) comprise iron ore pellets. The invention also relates to a method and a use of the thermal storage system (10).