Operators often use glycol dehydrators to remove water from natural gas. Triethylene glycol (TEG) dehydrators are the most common dehydrators used in oil and gas operations.
In the process, wet gas enters near the bottom of the glycol contactor and comes into contact with lean glycol (water poor) in the contact tower absorber. In the contact tower, water in the natural gas is absorbed by circulating glycol and the natural gas is dehydrated. The dehydrated gas is referred to as dry gas and exits through the top of the glycol contactor. The glycol that absorbed the water is called rich glycol (water laden).
The rich glycol then exits from the bottom of the glycol contactor and flows to the glycol flash tank (also called gas-condensate-glycol separator) to the glycol reboiler regeneration system. In the reboiler, the glycol is heated to boil off water from the glycol to produce lean glycol. This lean glycol is then sent back to the contact tower to repeat the cycle.
Flash gas from the glycol flash tank may be routed back to the system (fuel gas or sales) or sent to a flare or enclosed combustion device.
The reboiler uses heat and a still column to separate water from the glycol. The still column’s vent gas will contain mostly low-pressure water vapor and a smaller percentage of waste gas such as methane (CH4), benzene, toluene, ethylbenzene, xylenes, (BTEX) n-hexane and other VOCs. This source of vent gas is often required to be controlled by regulation. Also, companies wanting to reduce their methane emissions will want to destroy (combust) this source of greenhouse gases (GHG).
For a more detailed description of glycol dehydration unit process and air emissions consult the Cimarron blog titled, “Glycol Dehydration Process and Emission Controls.
Cimarron BTEX Eliminator Package
Cimarron’s solution to controlling glycol dehydrator emissions is the BTEX Eliminator. The BTEX Eliminator sends the still column vent gas to an exchanger/condenser (natural or forced draft, glycol shell and tube) to condense water and condensable hydrocarbons (e.g., VOCs/BTEX). The condensed water/VOCs are sent to the produced water tank using a blowcase or a pneumatic pump. Noncondensable, residual waste gas/VOCs are sent to the dedicated enclosed combustion device (ECD) for destruction.
For applications where glycol flash tank gas cannot be sent back to the system, this gas can be combusted by the unit’s dedicated ECD.
Dedicated OOOOa Combustor
Cimarron’s BTEX Eliminator package routes vapors to a dedicated high efficiency Quad-O certified combustor optimized for handling BTEX vapors, removing VOCs with an industry-leading destruction efficiency of 98%+. We use our Cimarron CH2.5 model ECD. These ECDs have casted ceramic fiber insulation that is better at handling water vapors. Also, the insulated ECD allows for better temperature control, thereby offering more flexibility to use assist gas and optimize ECD sizing to the unique needs of the facility.
Competitor units commonly route BTEX vapors to regenerator firetube burners. This method can be hazardous because the higher BTU content of still column vapors can make the gas unsuitable as a regenerator burner fuel gas. Often these vapors can condense and drop out leading to pooling of hydrocarbons in the reboiler firetube. Regenerator burners are typically not effectively sized to ensure adequate destruction of BTEX vapors.
Methane Destruction Efficiency
Many companies are seeking to reduce their methane emissions. Since the Cimarron BTEX Eliminator Package uses a dedicated Quad-O enclosed combustion device (ECD), the facility is assured that a methane destruction efficiency of 98%+ is attained.
As stated earlier, competitor units commonly route BTEX vapors to regenerator burners and this method would not attain a 98%+ destruction efficiency.
Also, flash gas from the glycol flash tank can be sent to the BTEX Eliminator’s ECD for destruction of methane and VOCs.
Methane emissions from the oil and gas industry is a target for more regulation.
Cimarron BTEX Eliminator Benefits
- Use of a dedicated Quad-O ECD makes it easy to demonstrate destruction efficiency of 98%+ of methane, VOCs and hazardous air pollutants (HAPs) benzene, toluene, ethylbenzene, xylenes and n-hexane.
- Eliminates the need to send still column vapors to the reboiler which is a common cause of regenerator fires and reduced emissions control efficiency.
- Ability to send glycol separator (glycol flash tank) to an ECD for combustion.
- Allows for the continued use of Energy Exchange Glycol Pumps due to 99% gas consumption destruction.
- Compact design provides small footprint.
- EPA compliant Quad-O ECD vapor destruction (5 Enclosed Combustor)
- Designed to address the increasingly stringent EPA and state environmental regulatory standards specific to natural gas dehydration emissions.
- Skid mounted (no assembly required) and fully enclosed models available for severe cold weather service and open air for warm weather service.
- All wetted parts are 304 Stainless Steel
- Fully ASME code construction
- On-site vapor destruction data logging and/or SCADA communication available.
- Multiple configurations available to couple with standard Glycol Regenerator Reboiler Duty Size 250MBTU/Hr up to 3MMBTU/hr+.
Glycol Dehydrator Emission Regulations
EPA regulations affecting glycol dehydrators include the hazardous air pollutant rules (HAPs) in 40 CFR 63 Subpart HH—National Emission Standards for Hazardous Air Pollutants From Oil and Natural Gas Production Facilities. Also, 40 CFR 63 Subpart HHH – National Emission Standards for Hazardous Air Pollutants (NESHAP) for Natural Gas Transmission and Storage.
Also state specific environmental regulations apply to glycol dehydrators.
Cimarron BTEX Eliminator packages meet all federal and state emission control requirements for glycol dehydration units.
Summary and Conclusions
Glycol dehydration units emit methane, VOC and hazardous air pollutants (HAP) such as benzene, toluene, ethylbenzene, xylenes (BTEX) and n-hexane. Current federal and state regulations require the control of glycol dehydrator’s VOC and HAP emissions. The need to reduce methane emissions from the oil and gas industry is expected to be required by future regulation (NSPS OOOOb/c).
Cimarron’s BTEX Eliminator Package is an effective, reliable method to control air emissions from glycol dehydration units. Our packages meet all federal and state regulatory requirements for controlling dehydration unit emissions. Since our BTEX Eliminator uses a dedicated enclosed combustion device (ECD) to control noncondensable gases, a destruction efficiency of 98%+ can be safely and reliably attained. This destruction efficiency is greater than that attained by emission control devices that send noncondensable gases to a reboiler burner. Also, the BTEX Eliminator’s ECD has capacity to combust flash gas from the glycol flash separator.
With the worldwide focus on methane emissions, the BTEX Eliminator’s 98%+ destruction efficiency is needed.
Cimarron – Who We Are
Cimarron’s overall goal is to reduce greenhouse gas emissions for all industries as we 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 BTEX Eliminator, 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 firstname.lastname@example.org or visit our website www.cimarron.com.