Hybrid Fuel Supply System for LNG Carrier Engine
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Solution Overview
Problem
Current fuel supply systems for high pressure gas injection engines in LNG carriers are costly due to redundant equipment requirements, inefficient use of boil-off gas (BOG), and unstable fuel supply when BOG generation is low, leading to unnecessary BOG reliquefaction and combustion.
Innovation Solution
A hybrid fuel supply system that includes a compression device for compressing BOG and a high pressure pump for vaporizing LNG, allowing selective use of BOG or LNG as fuel based on vessel conditions, with a single set of multi-stage compression device and pump to reduce redundancy and costs, and eliminating the need for reliquefaction systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two sets of compression devices are provided for redundancy in high pressure gas injection engine, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The system dynamically switches between BOG compression mode and LNG pumping mode based on operational conditions. The single compression device adapts its function through dynamic configuration changes, eliminating the need for static redundant equipment while maintaining fuel supply reliability throughout the voyage.
Solution Approach 2:
The compression device is designed to perform multiple functions: compressing BOG during loading/cruising phases and pumping LNG during ballast/unloading phases. This multi-functionality allows one piece of equipment to replace what would traditionally require two separate systems, reducing complexity while maintaining reliability.
2Reliability
If BOG is burnt in gas combustion unit to adjust cargo tank pressure, then pressure control is achieved, but energy loss occurs
Solution Approach 1:
The system converts what would be wasted BOG (a harmful factor when burnt unnecessarily) into a beneficial fuel source for the main engine. By utilizing BOG as fuel during phases when it would otherwise be burnt, the system transforms energy loss into useful work, improving overall energy efficiency while maintaining pressure control capabilities.
3Reliability
If high pressure pump and vaporizer are used to supply LNG as fuel, then fuel supply stability is improved, but device complexity increases
Solution Approach 1:
The compression device serves dual purposes: compressing BOG to high pressure for direct engine supply, and pumping LNG to high pressure followed by vaporization for engine supply. This multi-functional design eliminates the need for separate pumping equipment, reducing system complexity while ensuring stable fuel supply under various operational conditions.
4Device complexity
If single set of compression device is used for both BOG compression and LNG pumping, then device complexity is reduced, but adaptability requirement increases
Solution Approach 1:
The compression device incorporates dynamic adaptability through variable displacement mechanisms and adjustable operating parameters. It can seamlessly transition between compressing BOG and pumping LNG based on real-time operational requirements, maintaining high adaptability with a single piece of equipment rather than requiring multiple specialized devices.
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 system enables cost-effective and stable fuel supply to high pressure gas injection engines by efficiently utilizing BOG when available and switching to LNG when BOG generation is low, reducing waste and equipment costs while maintaining engine operation.
Implementation Method 1
a compression device configured to compress boil-off gas (BOG) generated from liquefied natural gas (LNG) stored in an LNG cargo tank
Implementation Method 2
a high pressure pump configured to compress LNG supplied from the LNG cargo tank
Implementation Method 3
a vaporizer configured to vaporize the LNG compressed by the high pressure pump
Implementation Method 4
a dual fuel (DF) engine to which the BOG compressed through the compression device is supplied as fuel
Data Source
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AI summary
A hybrid fuel supply system for an engine of a vessel is provided. The hybrid fuel supply system for the engine of the vessel includes: a compression device configured to compress boil-off gas (BOG) generated from liquefied natural gas (LNG) stored in an LNG cargo tank; a high pressure pump configured to compress LNG supplied from the LNG cargo tank; a vaporizer configured to vaporize the LNG compressed by the high pressure pump; and a dual fuel (DF) engine to which the BOG compressed through the compression device is supplied as fuel. The engine of the vessel uses high pressure gas compressed at 150 to 400 bar as fuel and is driven by at least one of the BOG compressed in the compression device and the LNG compressed in the high pressure pump.