Flaring is the controlled burning of natural gas at production facilities, oil refineries and other industrial sites. While flaring reduces dangers associated with gas buildup, it also results in the loss of potentially valuable resources and contributes to greenhouse gas emissions. Given environmental regulations aimed at curbing emissions and the economic value of recovered gas, facilities are increasingly turning to flare gas recovery systems.
Flare gas contains methane, a potent greenhouse gas, as well as ethane, propane and butane which have commercial value as feedstocks or fuels. By recovering flare gas rather than flaring it, facilities can reduce their emissions footprint while also gaining a new source of revenue. Comprehensive systems can recover up to 98% of gases from flares, helping minimize waste.
Components of Effective Flare Gas Recovery
Successful Flare Gas Recovery System depends on optimized systems designed for safe and efficient operations. Key components usually include:
- Vapor recovery units to efficiently separate liquid and gaseous hydrocarbons for transport. Materials with low vapor pressures like crude oil cannot be recovered through standard compression.
- Flare header and knockout drums where combusted gases are cooled and separated into liquid and vapor streams before further processing or storage. Proper drum sizing is critical.
- Compressors to pressurize recovered gas for pipeline injection or further processing. Reciprocating, centrifugal or screw compressor designs may be used depending on throughput needs.
- Piping and pipe racks to convey separated gases and liquids from flare header to recovery equipment and storage facilities. Heat tracing may be needed depending on environmental conditions.
- Control and instrumentation systems for automated monitoring and fail-safe shutdowns. Systems must safely handle fluctuations in gas composition and flow rates.
- Gas chillers which lower temperatures to condense heavier hydrocarbon components and maximize recovery rates. Refrigerated glycol or evaporative systems are common.
- Storage tanks for stabilized oil, condensate and NGL products prior to sales or further refining. Tank sizes will vary by recovery rates, marketing schedules and product mix.
Careful design of all components is needed to ensure smooth integration, operability at facilities operating 24/7, and reliability in harsh environments. Proper maintenance is also crucial to sustain high recovery levels over the long term.
Recovering Specific Gas Constituents
The specific design of flare gas recovery systems is tailored to the composition of gases to be processed. Key considerations in recovering valuable gas constituents include:
Methane Recovery
At the core of most flare gas projects, methane compression allows facilities to reinject recovered gas into sales lines. Careful metering verifies quantities for netting against emissions. Membrane, absorption and cryogenic technologies further boost methane recovery rates.
Ethane Recovery
As an important petrochemical and heating fuel, ethane is increasingly in demand. Refrigerated absorption or cryogenic expander-Based processes are commonly used to segregate and stabilize ethane for pipeline transport or fractionation.
Propane/Butane Recovery
Like ethane, propane and butane are valuable natural gas liquid (NGL) products. Joule-Thompson valves, turboexpanders or mixed refrigerant processes separate these components as high-purity NGL streams or mixes.
Condensate Recovery
Heavier hydrocarbons including pentanes-plus are recovered as condensate through combination of gas chilling, drips and separator vessels. Facilities aim to maximize economic value through optimizing recovery processes.
Oil/Emulsion Handling
Oil and water processed through flare header systems require careful pumping, treating and storage to meet quality specifications for marketing. Both capital and operating costs are considered.
Optimizing Performance through Technology
Advances in digital instrumentation, automation, control systems and data analytics continue to enhance flare gas recovery project performance. Modern systems provide remote monitoring, preventative maintenance insights and alarm notifications to maximize uptime.
Artificial intelligence and Internet of Things technologies are beginning to transform flare gas recovery. Digital twins allow modeling and optimization of recovery rates under all operating conditions. Predictive analytics identify maintenance needs before failures occur. Drones and computer vision support inspection and measurement tasks.
These digital innovations reduce variability in operations and troubleshooting needs. They also empower continuous improvement through testing "what if" scenarios. Overall system efficiency and profitable hydrocarbon recovery are optimized to generate the highest long-term value from previously flared gases.
Whether module packages or grassroots flare gas recovery facilities, optimized system designs tailored to gas composition are key. From handling various hydrocarbon components to employing the latest digital technologies, maximizing recovery rates in a safe, reliable manner helps industrial facilities reduce emissions while gaining a new revenue stream. As regulations and economics continue to prioritize minimizing flaring, recovered flare gas will become an increasingly important resource.
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