What’s the danger of having moisture in your natural gas pipeline?

Freeze-ups can happen anywhere. Prevent pipeline freeze-ups, like what occurred in Texas with a Deliquescent Natural Gas Pipeline dryer.

Think of all the natural gas pipelines in the US, all the wellheads located in cold or warm climates. There is no discrimination over where you live—a freeze up can happen anywhere, at anytime.

So, is it better to be safe or would you rather not be prepared for an unexpected cold weather event?

Prime example is happening right now. Much of Texas is experiencing weather like they have never seen. Single digit freezing temperatures, snow accumulations in the double digits, people are without heat and electricity.

In an article by the Washington Post on February 16th, Will Englund wrote "The Texas grid got crushed because its operators didn’t see the need to prepare for cold weather”.

The Texas winter snowstorm caused a tragic loss of life and whenever that happens you will see a lot of finger pointing going on. This is not that type of a post.

What causes water in natural gas lines?

Moisture exists at all times, in the gas coming out of ground and in the air around us. It really comes down to how much moisture is acceptable and entrained in air or gas at any one given moment or set of parameters.

In the case of natural gas, the distribution (or midstream partners) say the gas has a certain moisture spec at “these given conditions”, where it gets tricky is any change to these certain conditions, pressure, or temperature, the state of the moisture can shift. In this I mean, shifts from a vapor to a free liquid state and that is when it can become noticeable.

From compression, all the way down to where enters a home or business, the gas changes pressure several times, in each change in pressure it passes through a regulator which has a series of orifices and in that reduction it causes an instantaneous temperature drop. This is what is responsible for the production of water, from vapor phase to liquid phase and will show up in lines and equipment.

That being said, also from the transmission of gas through pipelines, there is just as much potential for temperature reduction, when traveling from point A to point B. If the gas is produced in the compression stage, it is warmed as a byproduct of the process, when traveling this gas can cool back down and release free liquids along the way.

Where Van Air Systems can help is anywhere the gas is intended to be used, we can remove that moisture that has collected before it can harm the use of that gas, moisture being present in any stage can cause a in-efficient burn. Removal of this moisture is important to protect the process of burning natural gas, as well as make it as efficient as possible.

So what is the danger to having moisture in your natural gas pipeline?

Freeze-ups can happen. Pipelines freeze up because of MOISTURE in the gas. Frozen equipment, power plants – STOP, just like that! We see the devastation that this caused in Texas this week and is still occurring. In Texas, a warm climate, freeze-ups are not something that come to mind to worry about. However look how quickly and how easily it can happen.

Deliquescent Natural Gas Pipeline Dryer - Van Air Systems/ Van Gas Technologies PLD series dryer

Natural gas comes out of the ground saturated with moisture. That moisture needs to be removed or it will cause problems. If the moisture is not removed, it will corrode burners, burn less efficiently, and in cold weather, the moisture will freeze and block the flow of gas.

How do you remove the moisture?

Removing the moisture is quite simple—you need a Natural Gas Dehydration Unit, aka: A Dryer. In warmer climates a TEG (Triethylene Glycol) Dehydration unit can be used, but to prevent freeze-ups in cold climates we use our PLD Deliquescent Natural Gas Dryer.

PLD Deliquescent Dryers can even be placed downstream of TEG dryers to act as backups or insurance against freeze-ups. The reason being is that a TEG dryer is basically a refrigerated dryer that uses cool glycol to absorb moisture and has a fixed moisture content(Dew Point) well above the freezing temperatures Texas is fighting right now. Our PLD Deliquescent dryer operates off of “Dew Point Suppression” which is a fancy way of saying that our dryers remain “x” degrees below the inlet gas temperature to the dryer. Our dew points fluctuate which is a tremendous advantage in colder climates because our dew point always remains below the inlet temperature to the dryer thus preventing freeze-ups.

The PLD Deliquescent Dryer is very simple and affordable solution. There is nothing complicated about this dryer. Its reliable, its durable, can be installed indoors or out. In a situation like Texas, this dryer is your peace of mind. It’s simple to operate and easy to maintain. It is a basic pressure vessel filled with desiccant tablet.

As the gas passes over the desiccant tablets, the moisture is absorbed, and the tablets slowly dissolve creating a liquid brine solution. The condensate falls to the bottom of the dryer’s reservoir where it can be drained out. In approximately 4-6 weeks, you will need to add more tablets to the top of the dryer which is as simple as removing the fill port nut and pouring in more desiccant. The PLD has no moving parts and does not require electricity. Just fill it with desiccant and you will have dry gas.

The best part is that the PLD Deliquescent dryer and the TEG Dehy can be used at the same site and/or for similar applications. We do not compete for business because each dryer type is used for different reasons, but a PLD can always be used as an emergency backup after a TEG dehy to prevent catastrophic failures.

What is happening in Texas right now is unfortunate, but rather than finger pointing at “what went wrong”, Van Air Systems/ Van Gas Technologies would like to be part of the solution moving forward. Rather than be mis-informed or believe that natural gas drying is not a necessity in a warmer climate, let’s use Texas as a case study to show that even warm climates can benefit from an inexpensive option to eliminate catastrophic failures. Reliability matters, being prepared matters. Our deliquescent dryers are there when you need them most. With our PLD Deliquescent Natural Gas dryers installed as the primary dryer or as point of use dryers for fuel gas, valve actuation, or other instrumentation gas applications you will not have to worry about freeze-ups shutting down your natural gas lines.

***Van Air Systems would like to say our hearts go out to all that have been affected by the storms down south. We are thinking of you all.***

References: 

The Washington Post: https://www.washingtonpost.com/business/2021/02/16/ercot-texas-electric-grid-failure/