Ship Engine LNG Return Channel for Boil-Off Gas Control
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Solution Overview
Problem
The existing fuel supply systems for ship engines using LNG face challenges in preventing system failure due to boil-off gas entering the high-pressure pump, which can disrupt the smooth supply of fuel.
Innovation Solution
A fuel supply system that includes a submerged pump in the LNG storage tank, a high-pressure pump for pressurizing LNG, and a return channel to regulate the flow rate of LNG upstream to maintain the temperature below liquefaction, preventing boil-off gas from entering the high-pressure pump, utilizing a flow control valve and temperature controller to ensure a minimum flow rate and supercooled LNG.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If LNG flow rate is increased to prevent boil-off gas, then temperature control is improved, but submerged pump minimum flow rate requirement may not be met
Solution Approach 1:
The LNG flow is divided into two separate paths: one path supplies LNG to the high-pressure pump for engine fuel supply, and another path returns LNG to the storage tank to maintain minimum flow rate. This segmentation allows independent control of temperature and flow rate requirements.
Solution Approach 2:
A return channel is introduced as an intermediary path that allows excess LNG to be returned to the storage tank. This mediator enables the system to maintain both the minimum flow rate for the submerged pump and the temperature control for preventing boil-off gas.
2Reliability
If return flow rate is increased to maintain temperature, then boil-off gas prevention is improved, but system complexity increases
Solution Approach 1:
A temperature sensor monitors the LNG temperature in the return channel, and this feedback signal is used by a control valve to automatically adjust the return flow rate. This closed-loop feedback system maintains reliable temperature control while automating the process.
Solution Approach 2:
The system dynamically changes the flow rate parameter of the return channel based on temperature conditions. By adjusting the return flow rate according to temperature measurements, the system maintains reliability while using simple parameter adjustment rather than complex mechanical systems.
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 solution prevents system failure by maintaining LNG in a supercooled state, preventing boil-off gas from entering the high-pressure pump, ensuring a smooth and reliable fuel supply to the ship engine.
Implementation Method 1
a submerged pump disposed in an LNG storage tank of a ship and supplying LNG to the ship engine
Implementation Method 2
a high-pressure pump receiving LNG from the submerged pump and pressurizing the LNG to a high pressure
Implementation Method 3
a vaporizer disposed in the fuel supply channel, re-gasifying pressurized LNG from the high-pressure pump
Implementation Method 4
a flow rate of LNG returned through the return channel is regulated to control a temperature of LNG in front of the high-pressure pump
Data Source
AI summary
Disclosed are a fuel supply system and method for a ship engine. The fuel supply system for a ship engine of the present invention comprises: a submersible pump which is provided to an LNG storage tank of a ship for supplying LNG to the engine of the ship; a high-pressure pump which has the LNG supplied thereto from the submersible pump and pressurizes the same under high pressure; and a return flow channel which, at the upstream of the high-pressure pump, returns the LNG to the LNG storage tank, wherein the flow of the LNG returning through the return flow channel is controlled, and the temperature of the LNG is controlled at the front end of the high-pressure pump.