Natural Gas Liquefaction Using Joule-Thomson Pressure Reduction
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Solution Overview
Problem
Current natural gas storage methods are limited by geological conditions and inefficient use of cold energy, leading to wasted resources and high costs, as traditional underground storage facilities rely on specific geological formations and conventional pressure reduction methods that do not effectively utilize cold energy for liquefaction.
Innovation Solution
A method utilizing the Joules-Thompson effect and a 'once through expander refrigeration cycle' to recover cold energy at metering and pressure reduction stations, diverting a portion of the natural gas stream for liquefaction as PLNG, LNG, or PNG, achieving cryogenic temperatures and reducing energy costs by integrating turbo expanders and heat exchangers to efficiently store natural gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional pressure reduction methods are used, then pressure is reduced, but cold energy is wasted and liquefaction efficiency is low
Solution Approach 1:
The patent converts the harmful temperature drop (cold energy waste) during conventional pressure reduction into a beneficial resource by using the Joules-Thompson effect to deliberately create cold temperatures for liquefying natural gas. The pressure reduction process that previously wasted cold energy now becomes the primary mechanism for achieving liquefaction.
Solution Approach 2:
The patent changes the operating parameters of pressure reduction by controlling the pressure drop to specifically achieve temperatures below the dew point of natural gas. By adjusting pressure from typical transmission levels down to storage pressures, the system transforms the pressure reduction process into an effective liquefaction method without requiring additional cooling equipment.
2Quantity of substance
If traditional underground storage facilities are built, then storage capacity is achieved, but location is limited by geological conditions
Solution Approach 1:
The patent changes the physical state parameter of natural gas from gaseous to liquid phase through pressure reduction and cooling. This phase change enables storage in above-ground tanks, eliminating the need for specific underground geological formations like salt caverns and allowing storage facilities to be located anywhere with suitable land.
Solution Approach 2:
The patent replaces the mechanical/geological system of underground salt cavern storage with a thermodynamic system using Joules-Thompson expansion and heat exchangers. This substitution allows storage in above-ground containers, providing location flexibility independent of geological conditions while maintaining storage capacity.
3Quantity of substance
If a portion of the gas stream is diverted for storage, then storage is enabled, but the main gas line flow is interrupted
Solution Approach 1:
The patent segments the natural gas stream into two separate flows: a main continuous flow through the gas line to end users, and a diverted portion through the storage system. The diversion is achieved through a T-connection or similar branching mechanism that allows independent control of each stream, ensuring the main line flow is not interrupted while enabling storage of a portion of the gas.
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 allows for flexible, cost-effective storage of natural gas in multiple locations, meeting peak demands, reducing pipeline reservation charges, and enabling local LNG production, while providing energy savings and operational flexibility, even in areas unsuitable for traditional underground storage.
Implementation Method 1
lowering the pressure of the stream of continuously flowing natural gas, thereby lowering a temperature of the continuously flowing natural gas by the Joules-Thompson effect
Implementation Method 2
raising the temperature of the continuously flowing natural gas solely by effecting a heat exchange in the at least one heat exchanger between the continuously flowing natural gas in the gas line and the diverted natural gas in the storage diversion line
Data Source
AI summary
A method of conditioning natural gas in preparation for storage, involves taking an existing stream of continuously flowing natural gas flowing through a gas line (12) on its way to end users and diverting a portion of the stream of continuously flowing natural gas to a storage facility through a storage diversion line (22). The pressure of the natural gas is lowered, as is the temperature by the Joule-Thompson effect. The natural gas is passed in a single pass through a series of heat exchangers (18, 28,30, 32) prior to resuming flow through the gas line (12) at the lowered pressure. The diverted natural gas is liquefied in preparation for storage by effecting a heat exchange with the natural gas.