Ambient Air LNG Regasification with Intermediate-Fluid Defrosting
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Solution Overview
Problem
Existing methods for regasifying liquefied natural gas (LNG) using ambient air as a heat source are inefficient due to ice and frost buildup, which reduces the effectiveness of ambient air vaporizers over time, making them unsuitable for continuous operation.
Innovation Solution
A process and apparatus that circulates an intermediate fluid between a vaporizer and an ambient air heater, where the intermediate fluid is warmed by ambient air and cooled by LNG, with a defrosting cycle maintained by regulating its temperature above zero degrees Celsius using supplemental heat, such as exhaust gas or engine heat, to prevent ice formation and ensure continuous operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If ambient air is used as the primary heat source for LNG vaporization, then environmental impact is reduced and fuel consumption is avoided, but ice and frost buildup on heat exchange surfaces reduces performance over time
Solution Approach 1:
The system implements periodic defrosting cycles where the ambient air heater is temporarily switched off and supplemental heat is applied to melt accumulated ice and frost. This periodic intervention restores heat exchange efficiency while maintaining continuous LNG vaporization operation, resolving the contradiction between environmental benefits and performance stability.
Solution Approach 2:
The defrosting system uses waste heat from LNG engine exhaust gases to melt ice on the ambient air heater surfaces. This self-service approach uses readily available onboard resources to maintain system performance without requiring external fuel consumption or significant additional energy input.
2Power
If seawater is used for LNG vaporization, then heat exchange efficiency is high, but environmental concerns arise from returning cooled seawater to the marine environment
Solution Approach 1:
The system uses ambient air as an intermediate heat source instead of seawater. The ambient air heater transfers thermal energy to the LNG through a heat exchange process, avoiding direct thermal interaction with the marine environment. This intermediary approach maintains efficient vaporization while eliminating the environmental harm of discharging cooled seawater.
3Ease of operation
If open rack type vaporizers are used, then operation and maintenance are easy, but construction costs are high and environmental permitting is difficult
Solution Approach 1:
The vaporization system is segmented into modular components: an ambient air heater module, a LNG heat exchange module, and a defrosting module with supplemental heating. This segmentation allows for easier installation, maintenance, and operation compared to traditional integrated open rack vaporizers, while reducing construction complexity through standardized modular units.
4Productivity
If ambient air vaporizers operate continuously, then productivity is maintained, but ice accumulation on heat exchange surfaces increases
Solution Approach 1:
The system maintains continuous LNG vaporization productivity by implementing rapid defrosting cycles that minimize interruption to the vaporization process. The supplemental heating system quickly melts accumulated ice, restoring heat exchange efficiency and allowing the system to return to full productivity with minimal downtime.
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 allows for efficient and continuous regasification of LNG using ambient air, minimizing emissions and operational costs by utilizing ambient heat and preventing ice buildup, thus maintaining the efficiency of the regasification process across varying temperatures.
Implementation Method 1
the intermediate fluid being warmed by exchanging heat with the ambient air as the intermediate fluid passes through the ambient air heater
Implementation Method 2
the intermediate fluid being cooled by exchanging heat with LNG as the intermediate fluid passes through the vaporizer
Implementation Method 3
with forced draft fans to enhance heat transfer
Data Source
AI summary
Liquefied natural gas is regasified to form natural gas, including circulation of an intermediate fluid between a vaporizer and an ambient air heater, where the intermediate fluid is warmed by exchanging heat with the ambient air as the intermediate fluid passes through the ambient air heater, and the intermediate fluid is cooled by exchanging heat with LNG as the intermediate fluid passes through the vaporizer. The ambient air heater is subjected to a defrosting cycle by intermittently regulating the temperature of the intermediate fluid fed to the ambient air heater to a temperature greater than zero degrees Celsius using a source of supplemental heat.