Vent Gas Management for Quad O Compliance
With the implementation of the EPA NSPS OOOO (Quad O) rules requiring oil and gas (O&G) facilities to reduce volatile organic compounds (VOCs) and methane emissions from storage tanks, it is critical to take a systematic approach to Vent Gas Management (VGM). Staying in compliance can be challenging with the alphabet soup of regulations.
Some components of a VGM system for compliance on an ongoing basis for are listed below.
Elements of an Optimal VGM System
- Identify all vent gas streams
- Quantify/measure vent gas streams
- Rectify the emissions with work practices or emission control devices, as needed
- Capture all emissions possible with a vapor recovery system (e.g., VRU), to provide payback economics for the full compliance program
- Monitor emissions – uncontrolled and controlled
- Take corrective actions, as needed
- Periodic review of results
How? – Parts of a System
- Use the IR camera technology to survey the site and identify any leak sources from the storage tanks. Examine storage tanks for leaking gaskets, improperly installed relief valves, holes, etc.
- Once tanks are sealed with no leaks and all gases can be directed to vent only through the thief hatch, meter the gas to quantify the volume (rate) of gas produced in the tanks. Measure for venting rate for 6 to 24 hour time period. Ensure that you identify the full range of cyclical flow of vent gas, as well as an average daily flow.
- Collect a gas sample of the vapor actually vented from the tank (i.e., take a pressurized sample from inside the tank) and have gas sample chemically analyzed to obtain gas BTU value, VOC content and methane content.
- Define the destination outlet for this vapor stream. Consider low pressure pipelines, fuel gas systems, site compressor inlets, etc. This will define the discharge pressure required by a vapor recovery system design.
- Once volumes/rates, gas analysis and destination outlet possibilities are defined, examine options to capture (e.g., VRU) or combust any vapor streams that exceed the NSPS OOOO limits.
- Automate the measurement and recording of vent gas volumes recovered by a VRU or sent to vapor combustion devices.
- Periodically monitor storage tank thief hatches and pressure/vacuum relief devices for leaks.
- Monitor all facility equipment for leaks (vents, fugitives) using auditory, visual, olfactory methods and Volatile Organic Analyzers (VOA) meters and IR Cameras.
- Use redundant emission control devices (e.g. VRU with vapor combustion devices) as back up to primary recovery. This will aid in compliance with NSPS OOOO and air permit requirements.
- Use vapor recovery towers (VRT) to capture flash gas.
- Implement a strong and defined preventative maintenance (PM) program for all equipment handling the vent gas stream to ensure maximum uptime.
Who Should Implement a VGM System?
- Oil and gas production and gathering facilities
- Midstream facilities
- Gas processing facilities
- Gas transmission facilities
- Crude oil and condensate storage facilities
What Vent Gas Sources?
- Storage tanks – crude oil, condensate, produced water
- Glycol dehydrators (still column vent, flash tank)
- Natural gas sweetening units (amine units)
- Low pressure blowdown vents
- Crude/condensate loading and unloading – tank trucks, railroad cars, barges
- Venting from well unloading
- Casing head gas releases
- Stuck separator dump valves
- Volatile organic compounds (VOCs)
- Benzene, toluene, ethylbenzene, xylenes (BTEX)
Why? – The Drivers
- EPA NSPS OOOO (40 CFR 60 Subpart OOOO) – current and future planned modifications
- Glycol dehydration unit emission standards in 40 CFR 63 Subpart HH and HH
- State air permits
- State and federal venting and flaring reduction initiatives (e.g., NDIC flaring order)
- EPA Natural Gas STAR program
- White House Climate Action Plan
- Safety considerations
- EPA NSPS OOOO (40 CFR 60 Subpart OOOO)
- EPA Gas STAR Program Technical Documents
- White House Climate Action Plan (CAP)
- HY-BON IQR Survey Methodology
- HY-BON Vent Gas Management
HY- BON’s Vent Gas Management (VGM) system can help your company to come into compliance and stay in compliance with the venting and flaring rules. Find out more by contacting HY-BON.