Flare Gas Recovery System Using Ejector and Membrane Separation
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Solution Overview
Problem
Existing flare gas recovery systems often require large footprints, high capital expenditures, and significant energy for operation, making them costly and impractical for many oil and gas sites, especially those with limited energy availability and space constraints.
Innovation Solution
A compact flare gas recovery system utilizing a liquid-driven ejector and a membrane system, which recirculates motive fluid to reduce energy consumption and system size, allowing for efficient recovery and valorization of flare gas with a smaller footprint and lower operational costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional compressor-based systems are used for flare gas recovery, then gas recovery efficiency is improved, but system footprint and capital expenditure increase significantly
Solution Approach 1:
The patent replaces traditional compressor-based mechanical compression systems with a membrane separation system that uses selective permeation to separate flare gas components. This substitution eliminates the need for large compressors and associated equipment, dramatically reducing the system footprint while maintaining gas recovery efficiency. The membrane system processes gas at lower pressures and requires minimal mechanical infrastructure.
Solution Approach 2:
The invention changes the operating parameters by using low-pressure membrane separation instead of high-pressure compression. The membrane system operates at significantly lower pressures, allowing the use of smaller, more compact equipment and reducing the overall system footprint while achieving effective gas separation and recovery.
2Productivity
If traditional compressor-based systems are used for flare gas recovery, then gas recovery efficiency is improved, but capital expenditure and operational costs increase
Solution Approach 1:
The patent replaces expensive compressor equipment with more cost-effective membrane separation technology. Membrane systems have lower capital costs, require less maintenance, and operate with lower energy consumption, thereby reducing both capital expenditure and operational costs while maintaining effective flare gas recovery.
Solution Approach 2:
The membrane system uses inexpensive, replaceable membrane modules that can be easily replaced when degraded, rather than investing in expensive, complex compressor systems requiring costly maintenance and repair. This approach reduces overall system cost and improves economic feasibility.
3Productivity
If traditional compressor-based systems are used for flare gas recovery, then gas recovery efficiency is improved, but energy consumption increases significantly
Solution Approach 1:
The patent substitutes energy-intensive mechanical compression with low-energy membrane separation processes. The membrane system separates gas components based on selective permeation at low pressures, consuming minimal energy compared to compressors that require continuous high-power operation to achieve the same separation and recovery objectives.
4Area of stationary object
If liquid-driven ejector with membrane system is used, then system footprint is reduced, but separation efficiency must be maintained
Solution Approach 1:
The invention optimizes membrane parameters such as pore size, material composition, and operating pressure differential to achieve high separation efficiency in a compact configuration. By carefully selecting membrane properties and operating conditions, the system maintains effective flare gas separation despite the reduced footprint and simplified 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
The system achieves efficient separation and recovery of flare gases with a smaller footprint (typically 30-50% less than traditional compressor-based systems), reduced capital and operational expenses, and the ability to operate in remote locations, facilitating the recovery of flare gas as Compressed Natural Gas (CNG).
Implementation Method 1
Ejectors rely on a Venturi effect to pressurize flare gas by utilizing available pressure from a motive fluid. The ejector converts the pressure energy available in the motive fluid to velocity energy, brings in the low pressure suction fluid, mixes the two fluids, and discharges the mixture at an intermediate pressure
Implementation Method 2
a membrane system in fluid communication with the first stage gas outlet. The membrane system may comprise a membrane configured to at least partly separate a gas fraction and a liquid fraction of the first stage fluid
Data Source
AI summary
The invention concerns a flare gas recovery system comprising a flare gas source suitable for discharging a multi-phase stream including materials in two or more thermodynamic phases such as natural gas (NG), natural gas liquids (NGLs) and/or water, a separator suitable for separating thermodynamic phases of an incoming fluid, an ejector configured to increase the pressure of the multi-phase stream and a membrane system configured to further separate gaseous fluid discharged from the separator. The invention also concerns a method using such a flare gas recovery system.