Routing crude oil storage tanks vent gas to a high destruction and efficiency (DRE) air-assisted flare can be used to ensure the 6 tons VOCs per year limits in NSPS OOOO/OOOOa are consistently met. Air-assisted flares can also be used to minimize methane emissions from natural gas blowdowns, associated gas flaring and storage tanks. These flares, if properly designed and operated, can achieve 99%+ DRE.
Using a high DRE flare can be part of a proactive system to ensure compliance with air quality regulations and permits.
Air-assisted flares improve combustion efficiency by introducing extra air into the waste gas stream using a blower system. The extra air flow causes turbulence, enhancing mixing and increasing combustion efficiency.
A proactive flare system would use a high DRE air-assisted flare that is properly designed, sized, maintained and monitored (including automated alerts and quick response time). A typical reactive (or passive) strategy for flaring waste natural gas does not include needed monitoring, alerts to operators and timely corrective actions to ensure flare gas is combusted for the maximum amount of time.
Elements for a proactive system using air-assisted flares would include:
- Proper sizing of the flare system to handle the expected minimum and maximum instantaneous flowrates.
- Enough motive force to send the gas to the flare tip.
- Pilot gas monitoring with alert notifications to operators for pilot system failure.
- Alerts would result in timely corrective actions to minimize un-lit pilots.
- Flare tip that optimizes air to gas mixture for maximum combustion of vent gas.
- Use of a variable frequency drive (VFD) controlled blower for the air assist system. This allows adjustment of the air to vent gas ratio to optimize combustion with varying flow rates to the flare.
- A monitoring and control system that uses an algorithm to automatically adjust the blower air to gas ratio based on gas flowrate and expected gas BTU value.
- Routine inspection and preventative maintenance of the system.
- Monitor, alert and take corrective actions for open thief hatches on storage tanks routed to a flare or VRU. Use Cimarron’s NOVENT™ to maximize the amount of vent gas is combusted.
Reasons for proactive flare system include:
- Reduce facility VOC emissions to comply with air permits (PBR, standard permits, etc.).
- Minimize methane emissions from venting from storage tanks, facility blowdowns and associated natural gas flaring.
- Reduce the possibility of a super-emitter event occurring a facility. Proposed EPA rules in 40 CFR 60, subpart OOOOb will engage third-parties to remotely monitor/quantify gas leaks (e.g., satellites, land based cameras) from O&G facilities. Companies that are cited as a super-emitter must conduct a root cause analysis, correct problems and report findings to the EPA. All of this data will be publicly available.
Example Emissions from High DRE Flare and Typical DRE Flare
Below (Case 1) is a comparison of flaring storage tank vent gas using a high DRE flare versus a typical DRE flare. VOC and methane emissions using a 99% DRE flare are 50% lower than using a typical 98% DRE flare.
|Case 1 – Storage Tank Vent Routed to Air-Assisted Flare|
|High DRE||Typical DRE|
|Flare volume (SCFD):||31,350||31,350|
|Gas mole weight (lbs/lb-mole):||44.3||44.3|
|VOC weight percent:||90%||90%|
|VOC tons per year:||6||12|
|Methane weight percent:||7.24%||7.24%|
|Methane tons per year:||0.48||0.97|
DRE = destruction and removal efficiency
Example Emissions from Blowdowns to Un-Lit Flare
The data below (Case 2) shows hourly methane emissions from an un-lit flare that receives about 156.4 MSCFD of a blowdown gas. This volume of vent gas could emit 100 kg per hour of methane if sent to an un-lit flare. This methane emission rate would be at the threshold of a methane “super emitter” as proposed by EPA in NSPS OOOOb rules. Detection of this level of methane emissions by a third-party recognized by the EPA would result in the operator needing to conduct a root cause analysis and report details on corrective actions taken. Super-emitter events must be reported in the OOOOb annual report.
Timely detection and corrective actions for an un-lit flare could prevent a “super emitter” event.
This amount of methane (from un-lit flare) would also affect fees (tax) for “excess methane emissions” based on the 2022 Inflation Reduction Act. For calendar year 2024, the excess methane emissions fee would be $900.00 per metric ton. Details on how the methane fee will be implemented will be based on future rule changes to 40 CFR 98 subpart W regulations.
|Case 2 – Natural Gas Blowdown Events Routed to Un-Lit Flare|
|DRE (flare not lit):||0%|
|Flare volume (MSCFD):||156.4|
|Methane mole percent:||80%|
|Methane kg per hour:||100|
DreamDuoTM Air-Assisted Flare
Cimarron’s DreamDuo™ air-assisted flares achieve a high DRE when using the DRE-Max™ smart control system and Sytelink360™ for automated alerts and performance monitoring to maximize pilot operation. The DRE-Max™ system employs an algorithm using field data to manage air assisted flares. It employs a proprietary algorithm that uses preprogrammed gas BTU values and reads gas flow rates from one or two flow transmitters. Additionally, it adjusts the air from a VFD-controlled blower to ensure optimal combustion in the air-assisted flare. Using DRE-Max™ in conjunction with a VFD and flow transmitter can effectively address compliance concerns. Other features include:
- Proper sizing and design for the expected operating conditions
- Destruction and Removal Efficiency (DRE) 99%+
- 100% Smokeless Performance
- 40 CFR 60.18 Compliant
- High Pressure / Low Pressure Dual Tip
- Fully Automatic Control w/ DRE-Max™ Controller
- Patented Technology
Further enhance the amount of gas controlled by emission control devices by using Cimarron’s NOVENT™ system to monitor storage tanks for open thief hatches. Furthermore, our aftermarket services can actively ensure that emission control equipment operates effectively and is well-maintained.
Summary and Conclusions
A proactive system for managing vent gas emissions is essential to ensure compliance with air quality regulations and permits. Such a system could use a high DRE air-assisted flare that is properly designed, sized, maintained, and monitored with automated alerts and quick response times.
Proactivity is the key to minimizing methane emissions from natural gas blowdowns, associated gas flaring, and storage tanks. By using a high DRE flare, which achieves 99%+ destruction efficiency, companies can significantly reduce facility VOC emissions and the possibility of a super-emitter event occurring. Additionally, a proactive flare system would involve routine inspections and preventative maintenance of the system, as well as monitoring and taking corrective actions for open thief hatches on storage tanks routed to a flare or VRU. Ultimately, a proactive approach to vent gas management will help companies reduce emissions and avoid costly fees/taxes associated with future methane emissions.
Cimarron – Who We Are
Cimarron’s vision is to work with our clients to create a cleaner environment. The company engineers and manufactures environmental, production and process equipment for the upstream, midstream and downstream energy industries, as well as environmental control solutions for biogas at wastewater facilities, digester tanks and landfills. Our flares and ECDs meet all federal and state environmental regulatory requirements for control efficiency and destruction efficiency.
Cimarron offers our customers the know-how and environmental expertise to meet the environmental standards of today and tomorrow. Cimarron is committed to bring value to the Energy industry and their shareholders based on our financial strength, experienced personnel, and engineering capabilities.
As a company, we thrive every day to make a difference through innovation (e.g. ESG), customer focus, and operational efficiency. In addition to being present in all major regions in the US, Cimarron serves more than 45 countries around the world, ranging from offshore to desert. From key operational centers in the United States, Italy and the United Arab Emirates, Cimarron offers ongoing service and support through its own field service personnel and strategic third-party partners, creating a cleaner environment for our customers and their shareholders.
Since its founding in the mid-1970’s in Oklahoma, the company’s product offering has expanded from production equipment to include the largest line of environmental solutions that capture or incinerate fugitive vapors. With the acquisitions of HY-BON/EDI in 2019 and AEREON (including Jordan Technologies) in 2020, Cimarron has added strong brands, products, and services to its portfolio.
Please contact us to learn more about our products and services and about all our ESG solutions at email@example.com or visit our website www.cimarron.com.