Thermal Boil-Off Gas Compression for Cryogenic Hydrogen Storage
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Solution Overview
Problem
The generation of boil off gas during the withdrawal of cryogenic fluids from storage tanks increases tank pressure, necessitating energy-intensive and costly atmospheric release or compression, which is inefficient and environmentally harmful.
Innovation Solution
A method utilizing a cryogenic pump, vaporizer, and thermally driven compressor to compress and store boil off gas in a buffer tank, leveraging the temperature differential of the cryogenic fluid for energy-efficient operation, without additional power or connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If boil off gas is released to atmosphere, then tank pressure is reduced, but energy is wasted and greenhouse effect increases
Solution Approach 1:
The invention converts the harmful boil-off gas that would normally be released to atmosphere into a useful resource by compressing it and storing it in a buffer tank. The gas is no longer waste but a storable product, eliminating both energy waste and greenhouse effect while maintaining tank pressure control.
Solution Approach 2:
The invention changes the pressure parameter of the boil-off gas by using a compressor to increase its pressure from tank pressure to buffer tank pressure. This parameter change enables the gas to be stored in a different phase and location, transforming it from a harmful release into a useful stored resource.
2Use of energy by moving object
If thermally driven compressor is used, then energy consumption is reduced, but device complexity increases
Solution Approach 1:
The thermally driven compressor uses heat from the cryogenic fluid itself as the driving energy source, making the system self-sufficient. The heat exchange between the cold cryogenic fluid and the warmer compressor mechanism provides the thermal energy needed for compression without external power input, reducing energy consumption while accepting increased device complexity.
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
Reduces energy consumption and operational costs while preventing atmospheric release of boil off gas, particularly effective for hydrogen storage by utilizing the waste energy from the liquefaction process.
Implementation Method 1
The vaporizer can be, for example an atmospheric or ambient vaporizer that causes the liquid cryogenic fluid to be vaporized by heat exchange with ambient air
Implementation Method 2
The compressor is a thermally driven compressor, i.e., a compressor that uses a cold source and a hot source, i.e., two sources of different temperature, for operation
Implementation Method 3
In an embodiment, a metal hydride compressor is used as said thermally driven compressor. Such metal hydride compressor is working on the principle of reversible absorption and desorption of hydrogen in a metal hydride driven by two heat sources
Implementation Method 4
boil off gas is generated due to heat input, cooling down of the pump and friction
Data Source
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AI summary
The invention relates to a method for removing boil off gas when storing cryogenic fluid (H2) in a storage tank (110), wherein a cryogenic pump (130) is used to pump fluid from the storage tank (110), in a liquid phase, to a vaporizer (140), wherein, in the vaporizer (140), the fluid is vaporized and provided in a gaseous phase, wherein the boil off gas is provided to a thermally driven compressor (120), and compressed by the thermally driven compressor (120), and wherein the thermally driven compressor (120) is operated using part of the fluid, in the liquid phase from before the vaporizer (140) as cold source (122), and using at least part of the fluid, in the gaseous phase from after the vaporizer as hot source (124).