How do weather changes affect the efficiency of flare gas recovery systems

As the oil and gas industry increasingly prioritizes environmental sustainability and carbon reduction, flare gas recovery systems are crucial for improving energy efficiency and reducing emissions. However, these systems do not operate efficiently under all conditions. Studies have shown that weather variations, particularly temperature, wind speed, and atmospheric turbulence, can affect the efficiency of flare gas recovery systems.

Relationship between Wind Speed and Flare Gas Recovery Efficiency

Wind speed is one of the most critical external environmental factors affecting the efficiency of flare gas recovery systems. Wind speed not only alters the shape of the flare flame but also directly affects combustion stability and unburned hydrocarbon emission, thereby impacting the load, efficiency, and controllability of the recovery system.

Higher wind speeds lead to greater emissions of unburned hydrocarbons

Field studies and controlled experimental studies show that flame lateral shift when wind speed is above some threshold i.e. usually above 5 – 7 m/s resulting in low combustion efficiency.

When wind speed is increased from 2 m/s to 10 m/s, the amount of unburned hydrocarbons emitted from the flare increases by 55% – 70% that directly causes instability in the composition of the gas drawn to the recovery unit which lowers the recovery efficiency. At > 8 m/s, flame length is reduced by 22% and the temperature of combustion zone decreases by 18% resulting in increased unburned light hydrocarbons. The prevalence of flame lift-off increases 2.4-times at high wind speeds which contribute to the reduction of flare combustion efficiency from 98% to < 85%.

Tropospheric disturbances at high wind speeds lead to flame instability, flame blow-off and flame tilting which weakens the gas-oxygen mixture resulting in incomplete combustion.

Therefore the recovery system has to handle more unburned, highly volatile gases leading to more instability and inefficiency.

Moderate Wind Speeds Help Max Recycling Efficiency

Moderate wind speeds of 3-5 m/s keep the flame stable and avoid fuel combustion flame out and air fuel mixture turbulence. Having a steady wind important for efficiency recovery of combustion systems. The recovery combustion systems remaining efficiency is 97-99% meaning the recovery combustion is meeting stable residual gas and is improving the entire system efficiency. Combustion systems without wind (<1 m/s) causes excess heat build up which increases flame flicker frequency and is harmful for the recovery system.

With that in mind, having a wind speed in the range of 3-5m/s is the most optimal for recovery of combustion gas systems.

Severe Strong Winds Case Extreme Combustion Instability Results

Multiple CFD simulation results, industry engineering experience, and monitoring data from operational sites in different countries all show that when the wind speed exceeds 12–15 m/s, the flare combustion will enter a highly unstable range, directly leading to a significant reduction in the efficiency of the flare gas recovery system, and even requiring shutdown for protection.

Wind Speed and Flare Gas Recovery Efficiency

Wind Speed (m/s)	Flame Condition	Combustion Efficiency	Recovery System Performance
0–1	Heat accumulation, slight flickering	90–95%	Unstable composition
3–5	Optimal stable zone	97–99%	Best recovery efficiency
6–10	Flame tilt	90–94%	Efficiency decreases
10–12	Clearly unstable	85–90%	Load fluctuations
≥15	Blow-off / incomplete combustion	<80%	Potential shutdown

Effect of Temperature on Flaring Gas Recovering Efficiency

Thermal effects on flare gas recovery efficiency are present at two points: at the combustion/flaring point and at the recovery unit.

Adverse Effects of Low Ambient Temperature Decrease Recovery Efficiency

Low temperatures impact the recovery unit’s efficiency, as well as increase complexity, as shown in multiple experiments and numerical simulations. Changes in the ambient temperature affect the gas processing in the compression, condensation and liquefaction phases due to changes in the fluid’s properties (density, viscosity), vapor pressures and phase equilibrium.

Low temperatures affect the gas’s viscosity and its density, potentially leading to changes in the flow velocity and Reynolds number in the pipelines, affecting the conditions at the compressor’s inlet and the heat transfer. Additionally, low temperatures increase the likelihood of condensation of lighter components and increase the viscosity of heavier components, leading to issues with transport and separation.

In the same cold box/mixed refrigeration scenario, lower temperatures of the ambient surroundings could mean the system requires more thermodynamic compensation (e.g. lower cold source temps, more refrigeration work is done). The less insulated the designs margins are, the lower the liquefaction rate will be (or the more power will be necessitated), impacting the economic factors and recovery rate more. Modeling and validation of ambient temperature in the field indicate that ambient temperature is a key parameter of liquefaction.

If the gas contains moisture or CO₂ and is at low temperatures, we can easily obtain ice blockage or CO₂ solid phase, and in heat exchangers or pipelines, we can force the gas system into reduction or shutdown for blockage removal and this reduces the available operation hours while affecting the average recovery rate for the year, this risk is especially true without proper dehydration or CO₂ removal pre-treatment.

Impact of Increased Surrounding Temperature on Recovery Efficiency

Increased temperature reduces liquefaction/compression efficiencies. There could be a greater difference in temperature needed to achieve a significant phase change. Additionally, there could be gas expansion, shorter residence time, and therefore decrease in recovery ratio. Also, highly elevated ambient and cooling water temperature reduces COP and liquefaction of gas.

Increased ambient temperatures result in increased cooling-side temperatures which increases workload and energy consumption of the refrigeration cycle. With increased power required for refrigeration it may increase the recovery costs while the gas refrigeration is at elevated temperatures for a prolonged period and a lower recovery may be actually achieved.

Increased temperature of gas expansion and reduced gas density will result in shorter residence time in heat exchanger and liquefaction unit which reduces the phase change. In condensation/liquefaction processes dependent on a certain residence time high temperatures will lead to directly lower the product yield.

Effect of Climatic Instant Thermal Variations on Temperature Stability

‘Weak’ temperature systems (with frequent day/night changes or pronounced seasonal rain changes) result in weak temperature systems (with frequent day/night changes or significant seasonal rain changes). Studies show temperamental systems employing automated control with temperature compensation experience far less efficiency losses when systems experience temperature changes.

How Temperature Affects Recovery Efficiency While Fire is Not Lit

Temperature is not as direct and important as combustion with regards to wind speed, but it is still an important factor to combustion. Ambient temperature varies and causes different flame stability and combustion temperature which ultimately gas entering the recovery unit higher, and changes the purification and liquefaction functions. (Especially at extreme highs and lows) In summary, temperature does recovery efficiency. combustion/ emission behavior . recovery feed characteristics.

Turbulence and Combustion Efficiency

A petrochemical plant or oil refinery’s flare systems act as a safety barrier, and impact energy use and carbon emissions efficiency. Considering global energy and ecological crises, flare gas recovery has garnered attention. There are multiple studies, including large eddy simulations, wind tunnel tests, and field industrial studies reveal increased turbulence is counterintuitive, leading to more unstable combustion and decreased recovery efficiency.

How Turbulence Affects Flare Combustion

Under normal conditions, flames are held steady by buoyancy and rotational air flow. But environmental turbulence overcomes this balance. Turbulence causes large tilt and change in shape of the flame and core combustion zone. It also causes instant air spikes and large drops in flame temperature. Subsequently, turbulence morphs the shape of the flame from a stable cone to an irregular, oscillating, and unstable configuration. Turbulence shifts combustion to the ‘idle’ state which leads to incomplete combustion, more rapid and unstable heat loss, more emissions, and a drop in recovery efficiency.

The Negative Impact of Turbulence on Combustion Efficiency

A series of wind tunnel tests and LES numerical simulations show that increased turbulence leads to excessive and erratic fluctuations of air entrainment over time. When turbulence increased from 5 to 20%, the instantaneous range of air entrainment fluctuations reached ± 40-55% and excess air entrainment lead to cooling of the flame and reduction of reaction intensity, and, conversely, the insufficient air lead to incomplete combustion, fuel wastage, and of course, negative environmental impacts. This erratic process contributes to the overall negative integrity of combustion combustion, and a resultant and significant decrease in combustion efficiency.

Combustion turbulence greatly disturbs the flame temperature field. A 2025 study performing large-eddy simulations found that at high-turbulence the decrement of flame center temperature is 18-27% and the flame reaction zone thickens. In addition, the reaction rates decrease, while the oscillation amplitudes of flame height under these high-turbulence conditions have been shown to reach over twice that of steady conditions. The temperature drop not only decreases combustion efficiency, but contributes to the combustion exhaust gas composition becoming more unsteady, and thus, fluctuations become inevitable in the load on the flare gas recovery system.

At last, big turbulence disrupts the low-pressure stability zone at the flare tail, essential for the extraction and recovery of closed flames. When turbulence disturbs the flame regularly and ruptures the stable zone, the flow path of the residual gas becomes chaotic, creating variations at the recovery inlet pressure of ±20–35% and resulting in a reduction in recovery flow rate of 8–22%. For larger recovery systems, the negative effect of these changes is more pronounced.

The Impact of Turbulence on Flare Recovery Efficiency

Parameter	Low Turbulence	Medium Turbulence	High Turbulence
Combustion Efficiency Drop	—	10–15%	20–30%
Recovery Efficiency Drop	—	8–12%	15–20%
Flame Displacement	Slight	Moderate sway	Significant tearing & drift
Recovery Inlet Pressure Fluctuation	Stable	±15–20%	±20–35%

Turbulence intensity is tied to the combust combustion efficiency and recovery efficiency. For every 10% increase in turbulence intensity, there is, on average, an 8% to 12% decrease in combustion efficiency and a 5% to 10% decrease in recovery efficiency.

The changes to a flame’s appearance due to turbulence are of secondary importance. The need for flare gas recovery systems has grown significantly. Understanding the influence of turbulence on combustion recovery efficiency will be paramount in the years to come to optimize energy efficiency and minimize CO2 emissions in the petrochemical industry.

Solutions Provided by KAITIAN GAS

KAITIAN GAS employs a multi-layer systematic approach designed to mitigate the impact of weather changes on flare gas recovery efficiency, ensuring constant and reliable operation under all weather conditions.

Modular and Adjustable Design

Modular systems mean fast changes in how you control irflow direction, wind shields, and outlet size needed as conditions like wind speed and cross-winds change. In the process and optimizing equipment design steps, KAITIAN GAS modular systems allow great custom-configuration in the field system, all while making future upgrades and expansion simple.

Remote Monitoring and Intelligent Control

Addressing the impact of environmental parameters in real-time monitoring the wind speed, temperature, and humidity, the PLC control, sensor networks, and remote monitoring platform adjust the compressor power, liquefaction temperature, and recovery pressure automatically. Based on the overall engineering design and EPC project execution experience, KAITIAN GAS illustrates that while intelligent control streamlining the combustion stability, the reduction of energy consumption and operational threats also increases.

Temperature and Pressure Compensation

During extreme temperatures, the system adapts on the fly their compression and liquefaction to allow a stable efficiency to be maintained. Conditions dictate action: with a cold snap, either more compression power is used or the gas is preheated; with high heat, the liquefaction temperature is lowered to shield the system from overheating. KAITIAN GAS expertly assesses the thermal parameters in the extreme ranges during the Detailed Design and Construction Drawing stages to allow the system to operate efficiently.

Combustion Stabilization Devices

Combustion wind speed and turbulence influence flame stability and combustion effectiveness. By threading internal flares, flow deflectors, and auxiliary burners, the system design optimally incorporates turbulence and wind disturbance, improving flame and combustion effectiveness. Optimized design further captures unburned remnants of the gas, offering a stable gas source that can be recovered and processed.

Comprehensive EPC Solution and Operation & Maintenance Support

Besides individual technical enhancements, KAITIAN GAS offers complete EPC project execution and long-term operation and maintenance support as well. From engineering design and process optimization to equpment installation and system operation, each stage addresses weather impacts to optimize recovery efficiency, reduce energy consumption, and prolong equipment lifespan.

Conclusion

Changes in the weather can affect wind speed, turbulence, temperature, and flare gas recovery efficiency due to combustion effectiveness and stability recovery system load. Energy-efficient, compact, and self-adaptive system designs, monitored in real time to reduce system control load, mitigate the impact of adverse weather on recovery system efficiency.

KAITIAN GAS aims to be the first in the world to create flare gas recovery and energy optimization solutions for the Oil and Gas Industry to enhance recovery efficiency and support oil and gas companies in gaining access to sustainable development goals. Through smart technological and engineering innovations, we guarantee every system we recycle is safe and eco-efficient.

Pick KAITIAN GAS so that your flare gas recovery system works seamlessly in every weather condition, and you can contribute to energy efficiency and a better environment.

References

Chen, Y., et al. (2023). Effect of ambient temperature and wind speed on combustion in flares. [Journal name].
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Burtt, D. C., Corbin, D. J., Armitage, J. R., Crosland, B. M., Jefferson, A. M., Kopp, G. A., Kostiuk, L. W., & Johnson, M. R. (2022). A methodology for quantifying combustion efficiencies and species emission rates of flares subjected to crosswind. Journal of the Energy Institute, 104(2022), 124–132.
Tao, C., Chow, J., Sui, L., Wang, A., Bottino, G., Evans, P., Newman, D., Venuturumilli, R., Lowe, J., & Liekens, J. (2024). Validation of a new method for continuous flare combustion efficiency monitoring. Atmosphere, 15(3), 356.
Mohit, A., Stolzman, J., Wooldridge, M., & Capecelatro, J. (2023). Impact of turbulence on combustion performance in non‑assist waste gas flares. [Preprint].