Boil-Off Gas Compression Control for Fluctuating Tank Pressure
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Solution Overview
Problem
Conventional boil-off gas supply devices face challenges in optimally managing the fluctuation between the generation and demand of boil-off gas, leading to suboptimal operation and increased gas pressure in storage tanks due to a common drive source for multiple stages of compression mechanisms.
Innovation Solution
A boil-off gas supply device with separate drive sources for first and second compression mechanisms, incorporating spillback mechanisms and pressure sensors for capacity control, allowing for independent adjustment of compression to match demand and generation, and a return path for re-liquefying excess gas to manage pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiple stages of compression mechanism are driven by a common drive source, then device complexity is reduced, but the ability to meet fluctuating boil-off gas demand and generation is worsened
Solution Approach 1:
The compression mechanism is divided into multiple independent stages, each with its own drive source. The first compression mechanism (low-pressure stage) and second compression mechanism (high-pressure stage) can operate independently, allowing each stage to be optimized for its specific function and controlled separately to match varying boil-off gas conditions.
Solution Approach 2:
The system transitions from a static common drive source configuration to a dynamic configuration where each compression stage has independent control. This allows the compression ratio and flow rate to be dynamically adjusted based on real-time boil-off gas generation and demand conditions.
2Use of energy by moving object
If the amount of driving the compression mechanism is reduced when demand is small, then energy consumption is reduced, but gas pressure in the storage tank rises
Solution Approach 1:
Pressure sensors are installed in the storage tank and at various points in the compression system to provide real-time feedback on pressure conditions. This feedback is used by the control unit to dynamically adjust the operation of the compression mechanisms, ensuring that boil-off gas is removed at an appropriate rate to maintain safe pressure levels while minimizing energy consumption.
Solution Approach 2:
The system changes operational parameters (compression ratio, flow rate, stage activation) based on measured pressure conditions. When pressure is high, the system increases compression activity; when pressure is low and demand is small, the system reduces compression to save energy, thus adapting to varying conditions.
3Adaptability or versatility
If separate drive sources are used for first and second compression mechanisms, then adaptability to demand fluctuation is improved, but device complexity increases
Solution Approach 1:
The drive source system is segmented into independent units, each controlling a specific compression stage. This segmentation allows for flexible operation where each drive source can be activated or deactivated based on system requirements, providing adaptability while maintaining manageable complexity through modular design.
Solution Approach 2:
Each independent drive source is designed to perform multiple functions: it can operate alone or in combination with other drive sources, can adjust compression ratio dynamically, and can respond to various pressure and demand conditions. This multi-functionality reduces the need for additional specialized components.
4Quantity of substance
If compression amount is increased to meet high demand, then gas supply adequacy is improved, but energy consumption increases
Solution Approach 1:
The compression system dynamically adjusts its operational state based on real-time demand conditions. When demand is high, the system activates additional compression stages and increases compression ratios; when demand is low, the system reduces compression activity. This dynamic response ensures adequate gas supply during peak demand while minimizing energy consumption during low-demand periods.
Solution Approach 2:
The system changes key operational parameters including compression ratio, flow rate, and active compression stages based on measured demand conditions. By continuously adjusting these parameters to match actual system needs, the system optimizes the balance between gas supply adequacy and energy consumption.
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 configuration enables optimal operation by adjusting compression based on demand and generation, preventing excessive pressure in storage tanks and ensuring efficient gas supply to meet varying demand pressures.
Implementation Method 1
a heat exchanger (44b) configured to cool the boil-off gas
Implementation Method 2
an expansion mechanism (44c) configured to expand and liquefy the boil-off gas cooled by the heat exchanger
Implementation Method 3
a first compression mechanism (C1) configured to suck in and compress the boil-off gas
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A boil-off gas supply device (10) is provided with: a storage tank (12) configured to store a liquefied gas; a first compression mechanism (C1) configured to suck in the boil-off gas of the liquefied gas stored in the storage tank (12) and compress the sucked boil-off gas; a second compression mechanism (C2) configured to compress the boil-off gas after being compressed by the first compression mechanism (C1); a discharge path (16) in which the boil-off gas discharged from the second compression mechanism (C2) flows; a first drive source (47) configured to drive the first compression mechanism (C1); and a second drive source (48) that is different from the first drive source (47) and configured to drive the second compression mechanism (C2).