Recompressed Transcritical CO2 Cycle for LNG Regasification
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Solution Overview
Problem
Conventional regasification technologies for liquefied natural gas (LNG) face inefficiencies in energy consumption and CO2 emissions, with Open Rack Vaporizer (ORV) and Submerged Combustion Vaporizer (SCV) technologies experiencing issues like fuel gas consumption, CO2 emissions, and complex operational requirements, while transcritical CO2 power cycles struggle with system stability and energy extraction.
Innovation Solution
A power generating cycle employing CO2 as the operating fluid, which involves pumping, heating, expansion in a turbine, cooling, and condensation, with a recuperator and recompression steps, allowing for efficient regasification and electrical energy generation by utilizing low and high temperature heat sources, and potentially integrating with existing SCV technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Open Rack Vaporizer (ORV) technology is used for regasification, then vaporization efficiency is improved, but seawater freezing and corrosion issues occur
Solution Approach 1:
The patent introduces an intermediate heat transfer fluid (organic working fluid) between the seawater and the LNG to perform heat exchange. This intermediary fluid transfers heat from seawater to LNG without direct contact, preventing seawater freezing on heat exchange surfaces and avoiding corrosion issues while maintaining vaporization efficiency.
2Productivity
If Submerged Combustion Vaporizer (SCV) technology is used for regasification, then regasification speed is improved, but fuel gas consumption and CO2 emissions increase
Solution Approach 1:
The patent converts the harmful CO2 emissions from SCV combustion into a useful resource by using CO2 as the working fluid in a transcritical power cycle. The CO2 that would be emitted is instead captured and utilized for power generation, transforming an environmental harm into a beneficial energy source while maintaining rapid regasification capability.
Solution Approach 2:
The patent changes the operating parameters from conventional subcritical conditions to transcritical conditions, utilizing the unique properties of CO2 near its critical point (31.1°C, 73.8 bar). This allows efficient heat transfer and power generation while eliminating fuel gas consumption and CO2 emissions associated with combustion-based SCV technology.
3Ease of operation
If conventional regasification technologies are used, then regasification function is achieved, but energy efficiency is poor and electrical energy consumption is high
Solution Approach 1:
The patent merges two separate functions (LNG regasification and power generation) into a single integrated system. The transcritical CO2 cycle serves dual purposes: transferring heat from seawater to LNG for regasification while simultaneously generating electrical energy, thereby improving overall energy efficiency and reducing net electrical energy consumption of the plant.
Solution Approach 2:
The patent establishes continuous useful action by using the temperature difference between seawater and LNG continuously to drive the transcritical CO2 power cycle. The CO2 continuously absorbs heat from seawater, condenses, and generates power throughout the regasification process, maximizing energy utilization without interruption.
4Power
If transcritical CO2 power cycle is used for power generation, then electrical energy generation is improved, but system stability becomes difficult to maintain
Solution Approach 1:
The patent optimizes operating parameters within the transcritical region to maintain system stability. By carefully controlling the CO2 pressure and temperature near its critical point, and by integrating the power cycle with the regasification process, the system achieves both high power generation and operational stability through parameter optimization.
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 approach reduces fuel gas consumption and CO2 emissions by up to 60%, enhances electrical energy generation, simplifies plant design, and improves thermodynamic efficiency, making it more cost-effective and environmentally friendly.
Implementation Method 1
heating in a recuperator, thus obtaining a heated flow
Implementation Method 2
vaporization and superheating
Implementation Method 3
condensing the operating fluid
Implementation Method 4
expanding in a turbine, with generation of electrical energy
Data Source
AI summary
A process for regasifying a fluid and generating electrical energy includes subjecting an operating fluid to 1) pumping, the pumping step including a low pressure pumping step 1a) and a high pressure pumping step 1b), 2) heating in a recuperator to obtain a heated flow, the heating step including a low temperature heat recovery step 2a) and a high temperature heat recovery step 2b), 3) further heating through a high temperature source to obtain a further heated flow, 4) expanding in a turbine, with generation of electrical energy to obtain an expanded flow, 5) cooling by heat exchange to obtain a cooled flow, and 6) condensing the flow of the operating fluid and regasifying the fluid. After low pressure pumping, a portion of the flow of the operating fluid is subjected to recompression to obtain a flow combined with the flow of the operating fluid obtained from step 2a).