LNG Train Sub-Cooling to Increase Capacity Without New Trains
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Solution Overview
Problem
LNG production is limited in existing trains operating at or above nameplate capacity, necessitating high capital expenditures for additional trains to increase production, while there is a need to enhance profitability and efficiency in LNG projects.
Innovation Solution
Configuring multiple LNG trains with a sub-cooling unit to sub-cool warm LNG streams, increasing the flow rate of cold LNG streams and thereby enhancing production capacity without constructing new trains, utilizing existing excess feed gas capacity and reducing construction costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If additional LNG trains are constructed to increase production capacity, then LNG production capacity is improved, but capital expenditures and construction costs increase
Solution Approach 1:
The system divides the LNG production process into two distinct operating modes: a first mode where each train produces warm LNG at nameplate capacity, and a second mode where sub-cooling units further cool the warm LNG to produce cold LNG. This segmentation allows the same physical infrastructure to deliver different product specifications and quantities, effectively increasing capacity without building new trains.
Solution Approach 2:
The system implements dynamic operation by allowing LNG trains to switch between first operating mode (producing warm LNG) and second operating mode (producing cold LNG through sub-cooling). The sub-cooling units are dynamically activated to adjust the final LNG temperature and flow rate based on demand, enabling flexible capacity optimization without permanent infrastructure expansion.
2Productivity
If sub-cooling units are added to existing LNG trains, then cold LNG flow rate is improved, but system complexity increases
Solution Approach 1:
The system segments the LNG production function into two independent components: the LNG trains that produce warm LNG at nameplate capacity, and the sub-cooling units that further cool the warm LNG to produce cold LNG. This segmentation allows each component to be optimized independently and operated flexibly, managing system complexity by creating modular, independently controllable units.
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
Increases LNG production capacity by generating a higher flow rate of cold LNG streams, reducing new construction costs and maintaining operational efficiency, with the added benefit of using nitrogen as a readily available refrigerant, thus minimizing additional refrigerant inventories and flare connections.
Implementation Method 1
A sub-cooling unit is configured to, in the first operating mode, sub-cool the first warm LNG stream and the second warm LNG stream to generate a first cold LNG stream in the first operating mode and a second cold LNG stream
Data Source
AI summary
A system and method for producing liquefied natural gas (LNG) from a natural gas stream. Each of a plurality of LNG trains liquefies a portion of the natural gas stream to generate a warm LNG stream in a first operating mode, and a cold LNG stream in a second operating mode. A sub-cooling unit is configured to, in the first operating mode, sub-cool the warm LNG streams to thereby generate a combined cold LNG stream. The warm LNG streams have a higher temperature than a temperature of the cold LNG streams in the second operating mode and the combined cold LNG stream. The combined cold LNG stream has, in the first operating mode, a higher flow rate than the flow rate of the cold LNG streams in the second operating mode.