Liquefied Gas Fuel Feeding System Return Line

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Solution Overview

Problem

Existing liquefied gas fuel feeding systems for internal combustion piston engines often result in gas leakage into the atmosphere during pressure regulation, which is environmentally harmful and undesirable.

Innovation Solution

A liquefied gas fuel feeding system with a return line from the second line section to the ullage space of the tank, equipped with a first pressure relief valve that opens when pressure exceeds a set pressure, and a conduit with a valve member extending between the pressure relief valve and the tank, allowing excess gas to be safely returned to the tank rather than released into the atmosphere.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a pressure relief valve is used to release excess gas from the second line section, then pressure control is achieved, but gas is discharged into the atmosphere causing environmental harm

Engineering Contradiction:
Improvepressure controlVSAvoidgas discharge to atmosphere
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The invention introduces a return line as an intermediary component that connects the second line section back to the tank's ullage space. This return line acts as a mediator that redirects excess gas away from atmospheric discharge and back into the storage system, where it can be reused or safely managed without environmental harm.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention converts the potentially harmful effect of excess gas discharge into a beneficial outcome by routing the gas back to the tank. The gas that would otherwise be wasted and harmful to the environment is now recovered and returned to the liquid gas space, where it can condense back to liquid phase or be reused, turning a harmful discharge into a resource recovery opportunity.

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

2Reliability

If gas is vented from the tank to control pressure, then pressure safety is maintained, but fuel loss occurs

Engineering Contradiction:
Improvepressure safetyVSAvoidfuel loss
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The invention implements a recovery mechanism by providing a return line that captures gas that would otherwise be discarded to the atmosphere. The gas is recovered and returned to the tank's ullage space, where it can condense back to liquid phase. This prevents fuel loss while maintaining pressure safety, as the gas is not permanently discarded but recovered and reused in the system.

Inventive Principle:
Principle #34Discarding and recovering

3Object-generated harmful factors

If the tank pressure is kept low to prevent gas discharge, then environmental protection is improved, but pressure regulation capability is reduced

Engineering Contradiction:
Improvegas leakage to atmosphereVSAvoidpressure regulation
Core Design Contradiction:
Object-generated harmful factorsVSAdaptability or versatility

Solution Approach 1:

The invention introduces dynamic pressure management through the return line system. The pressure in the second line section can be temporarily elevated above tank pressure to enable gas flow back to the tank, then reduced. This dynamic pressure regulation allows the system to adapt to varying operational conditions while maintaining overall pressure control and preventing atmospheric discharge.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention segments the pressure control function into two independent zones: the tank maintains low pressure to prevent discharge, while the second line section can operate at higher pressures for efficient gas delivery. The return line connects these zones, allowing pressure differential-driven flow back to the tank. This segmentation allows each zone to operate optimally without compromising the other.

Inventive Principle:
Principle #1Segmentation

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

Minimizes gas admission to the surroundings by routing excess pressure back into the tank, maintaining lower tank pressure and preventing atmospheric leakage, while ensuring safe operation and preventing damage from excessive pressure.

Implementation Method 1

a liquid fuel pump configured to raise the pressure of liquefied gas to a predetermined first pressure

Methodology Applied
Scientific EffectPressure increase: Pressurisation

Implementation Method 2

a gas evaporator configured to evaporate the liquefied gas at the first pressure

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 3

a first pressure relief valve configured to open when pressure in the second line section exceeds a set pressure

Methodology Applied
Scientific EffectPressure relief: Depressurisation

Data Source

PatentEP3619418B1A liquefied gas fuel feeding system and a marine vessel
Publication Date: 2023.07.19 WARTSILA FINLAND OY
  • EP3619418B1 patent drawingFigure 1
  • EP3619418B1 patent drawingFigure 2

AI summary

Invention relates to a liquefied gas fuel feeding system (10) for an internal combustion piston engine (12) comprising: a tank (14) configured to store fuel in cryogenic conditions, which when in use comprises a liquid gas space (14.1) having a surface (14.2) and an ullage space (14.3) above the surface (14.2); a fuel supply line (16) arranged to extend from the tank (14) to the internal combustion piston engine (12), the fuel supply line (16) comprising successively a first line section (16.1) and a second line section 16.2), wherein the first line section (16.1) is configured to receive liquefied gas from the tank (14), and comprising a liquid fuel pump (20) configured to raise the pressure of liquefied gas to a predetermined first pressure and a gas evaporator (24) configured to evaporate the liquefied gas into gaseous form at the first pressure, and wherein the second line section (16.2) is configured to receive gaseous gas from the gas evaporator (24), the second line section (16.2) comprising a gas valve unit (25) configured to open or close the flow connection between the gas evaporator (24) and the internal combustion piston engine (12), and the liquefied gas fuel feeding system (10) is provided with a return line (26) extending from the second line section (16.2) to the tank (14), the return line (26) opening into the ullage space (14.3) of the tank (14), and wherein the return line (26) is provided with a first pressure relief valve (28).