Liquefied Gas Pressure Booster With BOG Recovery Compression

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Solution Overview

Problem

Hydrogen filling stations experience significant boil-off gas (BOG) losses due to imperfect thermal insulation, leading to increased costs and reduced efficiency, as the BOG cannot be used for refueling.

Innovation Solution

A device with synchronized piston movements and check valves in a two-stage compression system, which recovers BOG from the pump container headspace and reintegrates it into the compression process, minimizing evaporation losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If thermal insulation is applied to minimize heat input to LH2, then evaporation losses are reduced, but perfect insulation is physically impossible and some BOG losses remain

Engineering Contradiction:

Improveevaporation lossesVSAvoidimperfect thermal insulation

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The invention converts the harmful BOG that would normally be vented into a useful resource by routing it through check valves into the compression chambers where it is compressed and returned to the liquid hydrogen system, transforming waste into a beneficial contribution to system operation

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

Instead of discarding the BOG through atmospheric venting, the system recovers it by capturing the evaporated gas through check valves and reintegrating it into the compression process, eliminating waste and improving overall system efficiency

Inventive Principle:

Principle #34Discarding and recovering

2Stress or pressure

If a pump reservoir is directly connected to the storage tank via supply and return lines, then LH2 can be compressed to high pressure, but the system requires significant thermal insulation which cannot be perfect

Engineering Contradiction:

Improvecompression pressureVSAvoidBOG losses

Core Design Contradiction:

Stress or pressureVSLoss of substance

Solution Approach 1:

The check valves act as intermediaries that selectively direct BOG flow into the compression chambers, enabling the system to capture and compress evaporated gas without disrupting the primary high-pressure compression function of the pump

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If BOG is released into the atmosphere via a stack to ensure safe constant pressure, then system pressure is stabilized, but significant cost factors arise from unusable gas loss

Engineering Contradiction:

Improveconstant pressureVSAvoidBOG losses

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The system recovers BOG that would otherwise be discarded through atmospheric release by capturing it through check valves and compressing it back into the liquid hydrogen system, eliminating waste while maintaining pressure stability

Inventive Principle:

Principle #34Discarding and recovering

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

Significantly reduces BOG losses to potentially zero, enhancing the efficiency and reducing operational costs of hydrogen refueling stations by reusing the recovered gas for compression.

Implementation Method 1

the check valve being designed to open as soon as the pressure in the compression chamber is lower than the pressure prevailing in the pump container

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Implementation Method 2

each of whose stages has a piston and each has a compression chamber, and wherein the piston movements are oscillating

Methodology Applied

Scientific EffectMechanical compression: Compression

Implementation Method 3

the aforementioned system components must be thermally insulated to minimize heat input to the LH2

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentEP4663995A1Device for increasing the pressure of a liquefied gas

Publication Date: 2025.12.17 LINDE AG

Figure 1

AI summary

A device for increasing the pressure of a liquefied gas and a hydrogen filling station that has such a device are described.