What You Need to Know About Gas Dehydration Units

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In the oil and gas industry, plant operators are constantly trying to find ways to remove contaminants and produce purer products. A major problem contaminant associated with natural gas is water vapor. To get rid of moisture from recovered natural gas, industrial manufacturers use different dehydration methods, like triethylene glycol processes.

Here's everything you need to know about gas dehydration units and how they can be used to eliminate unwanted moisture from recovered natural gas.

  1. What is a gas dehydration unit and what does it do?
  2. Components of a Glycol Dehydration Unit
  3. How do gas dehydration units work?
  4. What are the benefits of using them?
  5. Reasons to Remove Water Vapor from Natural Gas

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What is a gas dehydration unit and what does it do?

Glycol dehydrators, also known as gas dehydrators or TEG units, are used to remove water vapor from natural gas. The process of dehydration is important for two reasons.

First, water vapor can cause corrosion in pipelines and other gas-handling equipment. Second, water vapor can condense and freeze in low-temperature applications, which can result in clogged pipes and decreased efficiency.

To operate a gas dehydration unit, natural gas is passed through a tower containing a desiccant, such as molecular sieve or activated alumina. As the gas flows through the tower, the desiccant removes water vapor from the gas stream, leaving dry natural gas on the other side. Glycol dehydrators are typically used in natural gas processing plants and pipeline facilities.

Components of a Glycol Dehydration Unit

There are several vital components a glycol dehydration unit must have to properly dry natural gas. These key parts of a glycol drying setup include:

  • Inlet scrubbers
  • Contact towers
  • Reboilers
  • Surge tanks
  • Flash separator

While the first two components are crucial to natural gas drying, the latter three are primarily used for extracting water from the air so that it can be reused.

How do gas dehydration units work?

Glycol dehydrators, or TEG dehydration units, integrate natural gas drying phases with glycol regeneration processes. To start, water vapor mixed with natural gas is sent through a feed gas inlet on the gas scrubber which eliminates free water associated with it. As a result, most of the suspended water in the stream as well as particulate impurities and hydrocarbons are removed at this point. However, the natural gas is still not “dry” enough and must go through additional drying before use.

Afterwards, the gas is led through adjoining channels to a contact tower, where the concluding stage of drying occurs. A regular contact tower consists of several precisely positioned levels containing dehydrated or “lean” liquid glycol. Generally, natural gas is let in from below via an inlet at the bottom of the contact tower and rises until it reaches the top of the column while being in unceasing exposure to glycol fluid at different levels. As the gas continues upwards, any leftover moisture is extracted until finally exiting via an outlet channel at dried state ready for storage tanks or other treatment methods.

While this occurs, the glycol solution in the contact tower becomes "rich" as it absorbs moisture, and this necessitates its regeneration. As dry glycol is being fed into the process via one inlet, wet glycol is concurrently being removed from another outlet and channeled to a regeneration process.

The process of lean glycol reformulation starts with "wet" glycol being put into a three-stage flash separator. This machine removes any water vapor, particulate impurities, and oils that have accumulated. These contaminants are sent to storage tanks until they can be discharged later on. The now impurity-free glycol is moved to a reboiler unit.

The reboiler uses distillation to separate the water from the glycol. Water boils at 212oF, but for glycol, this number is 550oF. If ethylene glycol reaches 404oF, it will start to degrade--so most operators like to keep their processes between 212-400oF. The final step is eliminating any leftover water in the form of steam so that only dry glycol remains. This "lean" product can now be sent back to the contact tower where it will help with further natural gas dehydration cycles.

What are the benefits of using them?

Gas dehydration units are an essential part of the natural gas industry, and they provide many benefits. By removing water vapor from the gas, they help to prevent corrosion and freezing in pipelines.

In addition, they help to improve the quality of the gas, ensuring that it meets specifications for end use. Gas dehydration units are a critical part of the natural gas industry, and they provide many benefits to both producers and consumers of natural gas.

Reasons to Remove Water Vapor from Natural Gas

Disruptions to both the quality of natural gas and manufacturing equipment can occur when water vapor is retained within natural gas.

Some significant reasons for gas dehydration include:

  • Retained moisture will cause rapid corrosion of gas transport pipelines and storage vessels. Gas dehydration prevents oxidative reactions between water and metal pipes.
  • Prevention of hydrate formation to minimize the chances of pipeline plugging and/or erosion
  • Elimination of impurities that might affect gas quality supplied to various associated processes
  • Removal of water vapor from natural gas to improve its heating value, making it a more efficient form of energy in thermal processes
  • Removal of moisture from natural gas channeled through transport pipelines to prevent the formation of slugs that cause vibrational and mechanical strains, resulting in their rapid wear and breakdown

What are the different types of gas dehydration units available on the market today, and which one is right for you and your needs?

If you're in the market for a gas dehydration unit, you'll have a few different options to choose from. Glycol dehydrators and TEG units are the two most common types of gas dryers on the market today.

Glycol dehydrators work by passing the gas through a solution of glycol and water. The glycol absorbs the water from the gas, and then the gas is passed through a series of filters to remove the glycol.

Dehy units work similarly, but instead of glycol, they use a solid desiccant material to absorb the water from the gas. Dehydrators are also available with either forced or natural convection. Forced convection units have a blower that circulates the gas within the unit, while natural convection units rely on thermal currents to circulate the gas. When choosing a gas dehydration unit, it's important to consider your specific needs and application.

Glycol dehydrators are well suited for low-volume applications, while TEG units are better for high-volume applications. Dehydrators are also available in a variety of sizes to accommodate different flow rates.

12:eleven Offers Air-Drying Solutions for Industrial Use

At 12:eleven, we offer a broad range of efficient gas dehydration units useful in diverse industrial applications. We also provide cost-effective equipment and parts to optimize your industrial air-drying needs at all stages of manufacturing.

To learn more about our products and services, please contact us online today.New call-to-action

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About 12:eleven

As a specialty company providing custom design, engineering and fabrication of production and process equipment, we are dedicated to doing what’s right for our customers and passionate about creating value on every project.

We leverage the field expertise of our design and engineering group together with our diversified manufacturing capabilities to deliver a broad range of innovative surface production equipment - including Separators, Treaters, Free Water Knock Outs, Bulk and Test Packages, Indirect Line Heaters, Gas Production Units, Gas Dehydration Units, Glycol Contact Towers, Vapor Recovery Towers, Oil Stabilizing Towers.