System and method for harnessing energy from a pressurized gas flow to produce LNG
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Solution Overview
Problem
Current natural gas well production systems face inefficiencies due to high wellhead pressures, leading to costly emissions and equipment damage, and existing sand separators and gas production units struggle with high sand and liquid handling during flowback operations, requiring manual draining and lacking real-time feedback for optimal separation.
Innovation Solution
A system incorporating a heat exchanger, turbo expander, and separator that cools and expands the gas stream to separate vapors from liquefied natural gas, allowing for automated liquid level control and efficient separation of solids and liquids at high pressures, reducing emissions and equipment stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional choke valves and glycol-bath heaters are used to reduce pressure and prevent Joule-Thomson effect, then equipment damage and ice formation are prevented, but gas emissions increase and useful gas is consumed as fuel
Solution Approach 1:
The patent converts the harmful Joule-Thomson cooling effect into a beneficial liquefaction process. Instead of preventing the temperature drop that causes ice formation, the system harnesses this cooling to directly liquefy natural gas into LNG, turning a problematic effect into the core mechanism for product generation.
Solution Approach 2:
The patent replaces the conventional mechanical heating system (glycol-bath heaters burning gas) with a thermal exchange system using cold recyclers. The cold recyclers capture and reuse the cold energy from the expansion process, eliminating the need for combustion-based heating and preventing gas emissions.
2Productivity
If high wellhead pressure is maintained for efficient production, then gas flow rates increase, but pipeline wall thickness requirements and equipment stress increase
Solution Approach 1:
The patent segments the high-pressure gas flow into multiple parallel processing streams, each handled by individual cold recyclers operating at optimized pressure levels. This allows the system to process high total flow rates while distributing equipment stress across multiple smaller units rather than requiring one oversized high-pressure component.
Solution Approach 2:
The patent changes the physical state parameter of the gas from gaseous to liquid phase through controlled expansion and cooling. This phase change allows the system to handle high production rates while operating cold recyclers at lower, less stressful pressures, as the liquefaction process occurs during the expansion phase before distribution.
3Device complexity
If manual draining of sand separators is used, then equipment complexity is reduced, but operational time and sand handling efficiency decrease
Solution Approach 1:
The patent implements automated feedback control systems in sand separators that continuously monitor sand accumulation levels and automatically initiate draining operations when thresholds are reached. This feedback mechanism eliminates manual intervention while optimizing drain timing based on actual separator conditions, reducing both operational time and unnecessary draining.
Solution Approach 2:
The patent enables sand separators to perform self-service through automated monitoring and control systems that independently manage sand removal operations. The system self-regulates draining based on internal conditions without requiring external manual operation, thereby reducing operational time while maintaining simple overall system architecture.
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 solution enables efficient, automated separation of gas, liquids, and solids at high pressures, reducing emissions, equipment damage, and operational costs, while allowing for flexible site design and increased gas flow rates.
Implementation Method 1
The heat exchanger includes a first inlet for receiving a first pressurized gas stream, and a first outlet for outputting a chilled gas stream produced by the heat exchanger cooling the first pressurized gas stream
Implementation Method 2
The turbo expander is connected to the first outlet of the heat exchanger for receiving the chilled gas stream from the heat exchanger and producing a partially liquified gas stream
Implementation Method 3
The partially liquified gas stream is fed into the at least one separator, and the at least one separator separates the vapors from the LNG
Data Source
AI summary
A system includes a heat exchanger including a first inlet for receiving a first pressurized gas stream and a first outlet for outputting a chilled gas stream produced by the heat exchanger cooling the first pressurized gas stream. The system also includes a turbo expander connected to the first outlet of the heat exchanger for receiving the chilled gas stream from the heat exchanger and producing a partially liquified gas stream, the partially liquified gas stream comprising vapors and LNG. The system further includes at least one separator connected to the turbo expander, wherein the partially liquified gas stream is fed into the at least one separator, and the at least one separator separates the vapors from the LNG.