LNG Cooling for Natural Gas Injection into Storage Caverns
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Solution Overview
Problem
The existing methods for storing natural gas in salt caverns face limitations due to increased temperature and pressure, which reduce the gas mass flow injection rate into storage caverns.
Innovation Solution
The method involves using liquid natural gas (LNG) to cool the natural gas upstream of the compressor before injection into the cavern, thereby increasing gas density and mass flow rate, and optionally mixing the cooled gas with the compressor discharge to further decrease the outlet temperature and improve compression efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If natural gas is compressed for storage in salt caverns, then gas is stored in the cavern, but cavern temperature and pressure increase, reducing the gas mass flow injection rate
Solution Approach 1:
The patent applies preliminary cooling action by cooling the natural gas with LNG before compression. This pre-cooling reduces the initial temperature of the gas entering the compressor, which allows for higher mass flow rates during compression while maintaining acceptable outlet temperature and pressure conditions for cavern storage.
Solution Approach 2:
The patent changes the temperature parameter of the natural gas by introducing LNG as a cooling medium. This parameter change (lowering inlet temperature) enables increased gas density and mass flow rate through the compressor, directly addressing the contradiction between storage capacity and injection rate.
2Power
If gas temperature is increased during compression, then compression is efficient, but the rate at which gas can be added to the cavern decreases
Solution Approach 1:
The patent applies preliminary cooling before compression to establish a lower initial temperature state. This allows the compression process to achieve necessary pressure increases while maintaining lower outlet temperatures, thereby sustaining higher gas addition rates to the cavern without sacrificing compression efficiency.
Solution Approach 2:
The patent introduces LNG as an intermediary cooling medium between the gas source and the compressor inlet, and potentially between the compressor outlet and the cavern. This intermediary cooling system mediates the temperature rise during compression, enabling sustained high-rate gas addition while maintaining compression efficiency.
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 gas mass flow injection rate into storage caverns, increases storage capacity, and reduces compressor outlet temperature, thereby improving operational efficiency and storage capabilities.
Implementation Method 1
using liquid natural gas (LNG) to cool natural gas in a natural gas flow line upstream of a compressor
Implementation Method 2
LNG to cool the gas to storage
Implementation Method 3
a compressor used to compress gas for storage in to a gas storage cavern
Implementation Method 4
optionally mixing the cooled gas with the compressor discharge to further decrease the outlet temperature
Data Source
Figure 1
Figure 2
AI summary
A method to increase gas mass flow loading rates to a gas storage cavern includes using liquid natural gas (LNG) to cool natural gas in a natural gas flow line upstream of a compressor used to compress gas for storage in to a gas storage cavern.