TEG Dehydration Units for Natural Gas Processing

Custom TEG Dehydration Equipment

Every QB Johnson dehydration unit is custom-engineered for the application. The process starts with the gas analysis, flow rate, pressure, temperature, water content, required outlet specification, site requirements, applicable codes, and customer standards. From there, QB Johnson designs and fabricates a dehydration package that fits the project instead of forcing the project into a standard catalog unit.

A typical TEG dehydration package may include:

• Contactor tower
• Glycol reboiler
• Still column
• Flash tank
• Glycol filters
• Pumps
• Heat exchangers
• Piping and skid fabrication
• Instrumentation and controls
• Related scrubbers, separators, or filter separators where required

QB Johnson's in-house engineering and fabrication approach helps maintain control over quality, schedule coordination, documentation, and final fit-up. The same Oklahoma City operation supports ASME-code fabrication, QA/QC, pressure vessel work, piping, insulation, painting, electrical, instrumentation, startup support, and spare parts support.

Each package is also designed with field operation in mind. Component selection, skid layout, access points, instrumentation, and maintenance clearances should support dependable service after installation, not just a clean shop build.

How TEG Dehydration Works

A TEG dehydration unit operates on a continuous absorption and regeneration cycle. Wet natural gas enters the contactor tower and flows upward through trays or structured packing. Lean glycol enters near the top of the contactor and flows downward, contacting the gas and absorbing water vapor from the stream.

The dried gas exits the top of the contactor and continues downstream. The water-rich glycol exits the bottom of the contactor and moves through the regeneration system. In the reboiler and still column, heat drives absorbed water out of the glycol as vapor. The regenerated lean glycol is then cooled and returned to the contactor to repeat the cycle.

QB Johnson's proprietary Enhancelator produces lean TEG concentrations up to 99.5% wt. without the use of stripping gas, giving deeper regeneration for tighter dew-point control and lower glycol losses.

Dew-point depression stays essentially constant from 0 to 3,000 psig; standard units operate across a 50-135°F range, with lean glycol cooled to within 10°F of the inlet gas temperature.

System design affects outlet moisture performance, operating reliability, and long-term maintenance. Contactor sizing, glycol circulation rate, lean glycol concentration, reboiler duty, filtration, heat exchange, and controls all matter. For applications that require lower outlet moisture than a standard TEG system can provide, enhanced regeneration methods may be considered, or molecular sieve dehydration may be the better fit.

Applications for TEG Dehydration Units

TEG dehydration units are commonly used anywhere natural gas must be conditioned before transportation, processing, compression, or sale. QB Johnson designs and fabricates dehydration units for a wide range of operating environments and project requirements.

• Midstream gas gathering systems
• Production facilities
• Natural gas processing plants
• Pipeline transmission stations
• Gas storage fields
• Compressor station support
• NGL recovery pretreatment
• Offshore production platforms
• Sour gas and high-CO2 service

In many projects, the dehydration unit works alongside other gas conditioning equipment. Filter separators may be installed upstream to protect the glycol system from liquids, compressor oil, solids, or other contaminants. Thermal oxidizers may be used to handle still column emissions. Separators, heaters, gas plants, and amine units may also be part of the larger process package.

Protecting the Glycol System

Reliable dehydration performance depends on more than the contactor and reboiler. Contaminants in the inlet gas can affect glycol quality, cause foaming, reduce efficiency, increase maintenance, and create operating problems throughout the unit.

Filter separators and inlet scrubbers are often used upstream of TEG dehydration equipment to remove free liquids, particulate, compressor oil, and other contaminants before they enter the contactor. Proper filtration and separation help protect the glycol solution, extend equipment life, and support consistent outlet moisture performance.

QB Johnson evaluates the full process around the dehydration unit, not just the skid itself. That approach helps customers identify related equipment needs before the unit reaches the field, reducing the risk of startup problems or preventable operating issues.

How do you size a TEG dehydration unit?

Sizing a TEG dehydration unit starts with the gas: flow rate, operating pressure, inlet temperature, and the water the stream carries at saturation. The required outlet specification, whether that is a water content in lb/MMscf or a target dew point, then sets contactor diameter, tray or packing count, and glycol circulation rate. QB Johnson builds units from 60 MSCFD to 450 MMSCFD.

What types of glycol are used in dehydration units?

QB Johnson builds dehydration units using triethylene glycol (TEG) and diethylene glycol (DEG), with tetraethylene glycol (TREG) and ethylene glycol (MEG) also available as liquid desiccants for specific applications. TEG is the most common choice in production and midstream service because it regenerates readily and delivers the deepest dew-point depression of the common glycols.

What dew point can a TEG dehydration unit achieve?

QB Johnson glycol dehydration units deliver 50 to 110°F+ of dew-point depression and outlet water content of ≤7 lb/MMscf, with less than 1 lb/MMscf available where the application requires it. Dew-point depression stays essentially constant from 0 to 3,000 psig. The proprietary Enhancelator reaches 99.5% wt. lean glycol without stripping gas, which is what makes the tighter numbers repeatable.

What is the difference between the contactor and the reboiler?

The contactor is the vertical vessel where lean glycol falls counter-current to the rising wet gas and absorbs its water. The reboiler is the heated section of the regeneration skid that boils that water back out so the glycol can be reused. One takes water out of the gas; the other takes water out of the glycol.

How is BTEX handled on a glycol dehydration unit?

BTEX compounds (benzene, toluene, ethylbenzene, and xylene) may be present in raw natural gas, and small amounts may be absorbed into the glycol and later released with regenerator overhead vapors. Requirements are facility-specific and depend on gas composition, emissions rates, permits, and applicable regulations. Thermal oxidizers are one equipment option used to handle these vapor streams, and may be considered as part of the overall emissions control approach.
In some projects the dehydration unit, amine unit, and other process equipment are reviewed together to understand the full emissions profile. For more detail, see BTEX emissions and thermal oxidizers in natural gas processing.

TEG vs. Molecular Sieve Dehydration

TEG dehydration is often the right choice for standard natural gas dehydration applications where the target outlet moisture specification is around 7 lb/MMscf and the project requires a practical, proven, and cost-effective gas dehydration system.

Molecular sieve dehydration is used when the gas stream requires deeper water removal. It is commonly selected for cryogenic processing, LNG-related applications, NGL recovery support, or other services where very low water content is required to prevent freezing, hydrate formation, or damage to downstream equipment. For a fuller side-by-side, see the TEG dehydration vs. molecular sieve comparison.

If the best dehydration method is not clear, QB Johnson can review the process conditions and help determine whether TEG dehydration, molecular sieve dehydration, or a combined equipment approach is the better fit.

Built for Project-Specific Gas Conditioning Requirements

QB Johnson has built dehydration equipment for customers across domestic and international markets. With more than 1,000 dehydration units delivered and more than 60 years in business, the company brings long manufacturing experience to project-specific gas conditioning applications.

Each unit is supported by in-house engineering, ASME-code fabrication capabilities, ISO 9001:2015 certified quality processes, experienced trades, documentation, startup support, and spare parts support. For operators, engineers, EPC firms, and procurement teams, that means the equipment is designed and fabricated by a manufacturer that understands both the process and the field conditions the unit will face after delivery.

QB Johnson glycol dehydration units guarantee outlet gas dew points and unit performance.

Related Equipment

TEG dehydration units often work alongside other gas conditioning and processing equipment. Explore related QB Johnson equipment for inlet protection, emissions support, deeper dehydration, separation, heating, treating, and complete process packages.