Ship LPG Recirculation Cooling to Limit Flash Gas and Oil Buildup

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Solution Overview

Problem

The challenge in recirculation systems for internal combustion engines is the formation of flash gas and accumulation of oil components, which leads to inefficiency and increased energy consumption, particularly when using ammonia as a fuel.

Innovation Solution

A recirculation system with a recovery device, cooling unit, gas supply system, and recirculation tank, utilizing a control valve and sensors to manage fluid flow and pressure, ensuring efficient reuse of recirculated gas and minimizing flash gas formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If recirculation flow is cooled using a cooling device, then flash gas formation is prevented and fuel gas retention is improved, but energy consumption increases due to cooling requirements

Engineering Contradiction:
Improvefuel gas retentionVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The invention converts the harmful hot recirculation flow into a beneficial cooling resource by using it to cool incoming fuel gas, thereby preventing flash gas formation while recovering energy from the waste heat

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

Solution Approach 2:

The recirculation flow serves dual purposes: it is both the fluid being recirculated and the cooling medium for incoming fuel gas, making the system self-sufficient in terms of cooling requirements

Inventive Principle:
Principle #25Self-service

2Productivity

If recirculation flow is cooled to prevent flash gas, then system efficiency improves, but oil component accumulation may increase due to temperature-dependent viscosity changes

Engineering Contradiction:
Improvesystem efficiencyVSAvoidoil component accumulation
Core Design Contradiction:
ProductivityVSLoss of substance

Solution Approach 1:

The invention carefully controls the temperature parameter of the recirculation flow, cooling it only to the extent necessary to prevent flash gas while maintaining it above the pour point of oil components, thereby preventing accumulation

Inventive Principle:
Principle #35Parameter changes

3Reliability

If control valve is used to adjust fluid flow through recirculation line, then fuel gas retention is maximized, but system complexity increases

Engineering Contradiction:
Improvefuel gas retentionVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The control valve is integrated with the recirculation system to automatically adjust fluid flow based on system conditions, maximizing fuel gas retention through closed-loop control

Inventive Principle:
Principle #23Feedback

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

Maximizes fuel gas retention, reduces energy consumption, and prevents oil accumulation by controlling temperature and pressure, enhancing the efficiency and cost-effectiveness of the recirculation process.

Implementation Method 1

a cooling device which is configured to cool the recirculation flow supplied by the main machine and/or auxiliary machine

Methodology Applied
Scientific EffectCooling: Cooling

Implementation Method 2

the recirculation vessel is operated at a lower pressure than the recovery system and below the saturation pressure corresponding to the saturation temperature, so that so-called flash gas is generated in the recirculation vessel

Methodology Applied
Scientific EffectFlash gas formation: Flash Evaporation

Data Source

PatentEP4656864A1Recirculation system for recirculating recirculated drive liquid gas, corresponding method and use
Publication Date: 2025.12.03 TGE MARINE GAS ENG GMBH
  • EP4656864A1 patent drawingFigure 1
  • EP4656864A1 patent drawingFigure 2~3
  • EP4656864A1 patent drawing

AI summary

The invention relates to a recirculation system (2) for recirculating propulsion liquefied petroleum gas (LPG), in particular recirculated propulsion LPG from a main engine (4) and/or auxiliary engine (6) of a ship (100). According to the invention, it is proposed that the recirculation system (2) comprises a recovery unit (8), wherein the recovery unit (8) is fluidly connected to a main engine (4) or an auxiliary engine (6) via a supply line (10a, 10b) and comprises a cooling unit (26) configured to cool the recirculation flow (12a, 12b) supplied by the main engine (4) and/or the auxiliary engine (6), and a gas supply system (14) configured to supply propulsion LPG to the main engine (4) or the auxiliary engine (6).wherein the gas supply system (14) is fluidly connected to the recovery device (8) via a recirculation line (16) and wherein a control valve (18) for adjusting a fluid flow through the recirculation line (16) is associated with the recirculation line (16), and a recirculation tank (20) which is connected to the recovery device (8) via an inlet line (22) and to the gas supply system (14) via an outlet line (24).