Boil-Off Gas Recirculation for Flash Gas Liquefaction Efficiency
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Solution Overview
Problem
Conventional liquefied gas treatment systems waste energy by exhausting boil-off gas without utilizing it, leading to inefficiencies in temperature and pressure control for liquefied gas supply to consuming units.
Innovation Solution
A liquefied gas treatment system that pressurizes and supplies boil-off gas to a liquefied gas-consuming unit, decompresses and liquefies part of the boil-off gas, and uses flash gas as a cooling medium by recirculating it through a boil-off gas compressor, ensuring efficient energy utilization and increased mass flow to the compressor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If boil-off gas is exhausted without utilization, then the system is simple to operate, but energy is wasted and efficiency is reduced
Solution Approach 1:
The system uses boil-off gas itself as the working fluid to drive the compressor and as a cooling medium in the heat exchanger, making the waste resource serve the system's own needs for compression and cooling
Solution Approach 2:
Instead of discarding boil-off gas to the atmosphere, the system recovers it by routing it through the heat exchanger to cool compressed gas, then uses it to drive the compressor, and finally condenses it back to liquid form
2Productivity
If flash gas is not recirculated, then the system is simpler, but the mass flow to the compressor is insufficient and efficiency drops
Solution Approach 1:
The system implements a feedback loop where flash gas from the vapor-liquid separator is recirculated back to mix with boil-off gas before the heat exchanger, ensuring sufficient mass flow to the compressor and optimizing its operating efficiency
Solution Approach 2:
Flash gas serves multiple functions: it provides additional mass flow to the compressor, acts as a cooling medium in the heat exchanger, and helps maintain proper compressor operation without requiring separate control 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 approach enhances the efficiency of the boil-off gas compressor, reduces power consumption, and increases liquefaction efficiency, minimizing waste and improving driving efficiency by utilizing boil-off gas and flash gas effectively.
Implementation Method 1
a boil-off gas heat exchanger exchanging heat between boil-off gas, pressurized by a boil-off gas compressor and recovered along a boil-off gas supply line branching off upstream of a liquefied gas-consuming unit, and flash gas
Implementation Method 2
flash gas, supplied through a vapor-liquid separator
Implementation Method 3
boil-off gas, pressurized by a boil-off gas compressor
Implementation Method 4
decompresses and liquefies part of the boil-off gas
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A liquefied gas treatment system (2) according to the present invention includes a boil-off gas heat exchanger (60) exchanging heat between boil-off gas, pressurized by a boil-off gas compressor (50) and recovered along a boil-off gas supply line branching off upstream of a liquefied gas-consuming unit (20), and the boil-off gas, supplied from a liquefied gas storage tank (10), wherein the boil-off gas heat exchanger (60) exchanges heat between the boil-off gas, pressurized by the boil-off gas compressor and recovered along the boil-off gas supply line, and flash gas (17), supplied through a vapor recovery line.