Reduced Boil-off Thermal Conditioning System for LNG Storage
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Solution Overview
Problem
Current methods for filling natural gas storage tanks with liquid natural gas (LNG) result in significant boil-off and environmental concerns due to the venting of cryogenic fluid, leading to energy loss and greenhouse gas emissions.
Innovation Solution
A Reduced Boil-off Thermal Conditioning (RBTC) System that includes a cryogenic fluid tank, compressor, and throttling device, which pre-chills the LNG storage tank using a cryogenic fluid like nitrogen, reducing the need for venting and minimizing boil-off by maintaining the tank at a temperature equal to or below the LNG supply tank's temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the LNG storage tank is pre-chilled by venting cold LNG to the atmosphere, then the storage tank reaches the required temperature, but significant boil-off occurs and greenhouse gas emissions increase
Solution Approach 1:
A heat exchanger is introduced as an intermediary device between the LNG supply tank and the storage tank. The heat exchanger transfers coldness from the LNG in the supply tank to the storage tank walls and contents, enabling pre-chilling without direct venting to the atmosphere. This mediator allows thermal energy transfer while preventing harmful emissions.
Solution Approach 2:
The system converts the harmful venting process into a beneficial heat transfer process. Instead of releasing cold LNG to the atmosphere where it boils off and creates emissions, the same cold LNG is used through the heat exchanger to pre-chill the storage tank, turning a harmful emission source into a useful cooling mechanism.
2Temperature
If the LNG storage tank is pre-chilled by venting LNG to the atmosphere, then the storage tank reaches the required temperature, but significant energy loss occurs
Solution Approach 1:
The heat exchanger serves as a mediator that captures and transfers the thermal energy from the cold LNG before it would otherwise be wasted. By routing the LNG through the heat exchanger system, the coldness is transferred to the storage tank, and the LNG can be returned to the supply tank or utilized further, preventing energy loss.
Solution Approach 2:
Instead of discarding the cold LNG to the atmosphere where its cooling potential is lost, the system recovers this thermal energy through the heat exchanger. The cold LNG passes through the heat exchanger, transferring its coldness to the storage tank, and can then be recovered and reused in the supply tank, eliminating waste.
3Loss of energy
If a closed-loop recirculation system with compressor and throttling device is used, then boil-off is reduced and energy is conserved, but device complexity increases
Solution Approach 1:
The system establishes a continuous recirculation loop where LNG constantly flows through the heat exchanger, compressor, and throttling device. This continuous operation ensures that the storage tank remains pre-chilled and maintained at the required temperature throughout the filling process, preventing boil-off without requiring intermittent venting operations.
Solution Approach 2:
The system utilizes parameter changes in the LNG as it circulates: the compressor increases pressure and temperature of the LNG vapor, the throttling device reduces pressure and creates cooling effect, and the heat exchanger transfers thermal energy. These parameter changes enable the closed-loop system to maintain cooling without external venting.
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
The RBTC System effectively reduces LNG boil-off and maintains high pressure within the storage tank, minimizing environmental impact and energy loss by utilizing a closed-loop recirculation system that pre-chills and maintains the tank at a stable temperature.
Implementation Method 1
cooling the LNG storage tank to a temperature equal to or below a temperature of LNG within the LNG supply tank
Implementation Method 2
The compressor is in fluid communication with both the cryogenic fluid tank and the first LNG pipe
Implementation Method 3
the throttling device is in fluid communication with both the cryogenic fluid tank and the second LNG pipe
Data Source
AI summary
A Reduced Boil-off Thermal Conditioning System (“RBTC System”) for transferring liquid natural gas (“LNG”) from a LNG supply tank to a LNG storage tank with reduced boil-off is disclosed. The RBTC System includes the LNG storage tank, a cryogenic fluid tank within the LNG supply tank, and a compressor. The LNG storage tank includes a first and second LNG pipe. The cryogenic fluid tank is configured to store a cryogenic fluid within the cryogenic fluid tank and the first and second LNG pipe are in fluid communication with to the cryogenic fluid tank. The first LNG pipe is in fluid communication with compressor.