Heat storage system with underflow and overflow weirs
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Solution Overview
Problem
Existing sand heat storage systems in solar power plants face inefficiencies due to high energy consumption in transporting sand over long distances, corrosion, abrasion, and contamination issues, which reduce overall efficiency and increase operational costs.
Innovation Solution
A heat storage system utilizing a fluidized bed heat exchanger with vertically adjustable weirs and separate storage tanks for cold and hot sand, where sand is fluidized and transported within the heat exchanger using a blower, minimizing mechanical components and energy consumption, and allowing for efficient heat exchange and flexible operation modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sand is transported over long distances between heat absorption and heat release locations using pneumatic conveying systems, then heat storage and retrieval is enabled, but energy consumption increases significantly and efficiency is reduced
Solution Approach 1:
The patent combines the heat exchanger and sand storage function into a single integrated unit. The sand storage chamber is positioned directly adjacent to the heat exchanger chambers, eliminating the need for separate transport ducts and pneumatic conveying systems. Sand moves directly from storage into the heat exchanger chambers for heating or cooling, and then directly into the discharge chamber for retrieval, merging transport and heat treatment functions into one continuous process.
Solution Approach 2:
The patent introduces fluidized bed technology as an intermediary mechanism. A fluidizing medium (gas or liquid) is introduced into the sand storage and heat exchanger chambers, causing the sand to fluidize and flow automatically through the chambers without mechanical conveyance. This fluidized bed acts as a mediator that enables passive sand movement driven by density differences and fluid flow rather than active pneumatic transport.
2Productivity
If sand is used as heat storage medium in solar power plants, then thermal energy can be stored and released, but corrosion, abrasion, and contamination of components occur
Solution Approach 1:
The patent extracts sand from the traditional pneumatic conveying system and mechanical transport components. By using fluidized bed technology, sand is kept in a suspended state within the heat exchanger chambers and never comes into contact with mechanical conveying components, pumps, or ducts that would be subject to abrasion and contamination. The sand is contained entirely within the heat exchanger unit, separated from external mechanical systems.
Solution Approach 2:
The patent uses pneumatic principles through fluidized bed technology, where a gas or liquid fluidizing medium suspends and transports sand particles through the heat exchanger chambers. This pneumatic-hydraulic approach replaces mechanical conveyance systems, eliminating direct contact between sand and mechanical components that would suffer from abrasion and contamination, while still enabling effective sand movement and heat transfer.
3Ease of operation
If mechanical conveying devices are used to transport sand between storage tanks and heat exchanger, then sand transport is achieved, but device complexity and energy consumption increase
Solution Approach 1:
The patent replaces mechanical conveying devices (pumps, conveyors, valves) with a fluidized bed system driven by gas or liquid flow. Sand transport within the heat exchanger is achieved through fluid dynamics rather than mechanical forces. The fluidizing medium creates upward flow that suspends sand particles and carries them through the chambers, substituting complex mechanical transport mechanisms with a simpler pneumatic-hydraulic system.
Solution Approach 2:
The fluidized bed system is self-regulating and self-driven. Once the fluidizing medium is introduced, it automatically creates the conditions for sand to fluidize and flow through the chambers without requiring external mechanical control. The system uses its own operating conditions (fluid flow rate, pressure, temperature) to drive the sand transport process, eliminating the need for separate mechanical conveying devices and their associated controls.
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 solution reduces energy consumption, minimizes sand transport distances, prevents corrosion and contamination, and enhances heat exchange efficiency, making it suitable for solar and industrial applications while allowing for flexible energy supply, including nighttime electricity generation.
Implementation Method 1
at least one blower positioned underneath the heat exchanger for fluidizing the sand
Implementation Method 2
means for transferring heat from a heat source to the sand fluidized therein as well as means for transferring heat from the sand fluidized therein to a heat transport medium
Data Source
AI summary
A heat storage system using sand as a solid heat storage medium has a fluidized bed heat exchanger (3) arranged between and separated from a storage tank (1) for cold sand and a storage tank (2) for hot sand by weirs (4, 5). The heat exchanger (3) is divided into a plurality of chambers (7) by weirs (6). The weirs (4, 5, 6) are arranged as a combination of overflow and underflow weirs. Fluidized sand is produced in the chambers (7) by a blower (14) positioned underneath the heat exchanger (3). Heat is transferred from a heat source to the sand fluidized and from the fluidized sand to a heat transport medium by transferring mechanisms (8, 9) in the chambers (7). The sand is redirected in a horizontal direction by horizontally acting blowers and/or installations (12) projecting into a respective chamber from a side.