What Happens Inside Gas Compressor Stations?
Inside gas compressor stations, natural gas is cleaned, compressed, cooled, and re-pressurized before being directed back into pipelines. In some cases, excess heat is dissipated, and natural gas liquids are captured and removed.
Natural gas travels long distances from massive oil and gas fields to industry distributors and end users. Due to pipeline transportation, the delivery of natural gas has become safer, quicker, and more cost-effective than alternative methods.
Nevertheless, a few technical challenges rear their ugly heads from this transportation method.
When gas is transported over incredibly long distances, there is a significant pressure loss, including exposure to contaminants within these transportation channels. Moreover, friction, elevation differences, and distance slow the gas moving rate.
Therefore, the use of compression stations becomes essential to combat these challenges. Compression stations are the technical sentinels for gas flow measurement as they help boost diminishing pipeline pressures while simultaneously facilitating the onward movement of gas.
This article covers what you need to know about gas compressor stations and the activities that occur within them.
What is a Gas Compressor Station?
A gas compressor station is an industrial facility to efficiently stabilize the flow rate and pressure of natural gas in a pipeline network at the optimal levels needed to obtain a maximum carrying capacity.
Compressor stations are always strategically installed within the transportation and gathering pipeline network to help maintain natural gas flow and pressure to market.
How Does a Gas Compressor Station Work?
It is always essential for natural gas flowing through pipelines to get re-pressurized at intervals of approximately 40 to 100 miles. This enables the gas to continue its journey at the desired rate. In addition, the re-pressurization action corrects pressure losses that typically occur when gas travels great distances.
Cleaning and Compression
Natural gas enters the compressor station via a station yard piping. It is immediately passed through filters and scrubbers to eliminate solids, liquids, and other impurities – such as particulate matter – that the gas may have picked up from the oil and gas production field.
As soon as the stream of natural gas is thoroughly cleaned and has zero impurities, it is directed through additional yard pipping to independent compressors. Computers regulate the flow and the number of units required for handling the scheduled system flow requirements.
Most compressor units are designed to function in parallel, with independent compressor units providing the required additional pressure before directing the natural gas back into the pipeline. By this time, the full operational pressure has been fully restored via several compressor units operating serially in stages.
When natural gas undergoes compression, extreme heat is generated. This heat must be dissipated as soon as possible to cool the natural gas stream before it leaves the compressor facility.
For each 100 psi increase in pressure, the temperature of the stream of natural gas also increases by up to 8 degrees. Most compressor stations are fitted with aerial cooler systems that help dissipate excess heat. The heat generated by this operation is dissipated rapidly through a sealed coolant system quite similar to automotive radiators.
Natural Gas Liquids
In the areas that produce NGLs (natural gas liquids), better known as ‘wet gas areas,’ significant changes in temperature and pressure cause some of these liquids to drop out. But the liquids that drop out are readily captured in tanks and then trucked off the site.
The liquids captured are better known as drip gas or natural gasoline, which is often used as a premium blend in machine gasoline.
Powering Compressor Stations
Most functional compressor stations are powered by a small portion of the natural gas that flows through them. However, all or some of these units are electrically powered for security or environmental reasons in some parts of the country.
Natural gas turbine units or traditional piston engines may also drive every gas-powered compressor station. However, there are several operational and site design differences – as well as unique sound and air emissions – between competing compressor engine technologies.
Compressor Unit Housing and Design
The independent compressor units at a station may be one or more, and they can be housed in a building to facilitate sound and maintenance management or out in the open. Newer compressor units are generally housed singly per building, though it is common for multiple units to be set up in one large building.
The compressor units’ buildings are set up with shielded exhaust systems, insulated walls, and cutting-edge fan technology to suppress sound. All newly constructed compressor structures usually incorporate these features, especially,y where the local, state or even federal regulations require noise reduction.
Components That Make Up a Gas Compressor Station
At first glance, one would be tempted to believe that the reciprocating compressor is the most crucial part of a booster gas compressor station. But that is slightly far from the truth since other vital components are essential to the machine’s efficient function.
An ideal gas compressor or re-pressurization facility has the following vital components:
Prime Mover Units
The majority of functional high-pressure natural gas compressor stations make use of one of 3 types of engine/compressor systems to accomplish gas re-pressurization. Here are the prime movers, also known as the compressor drivers, arranged in no particular order:
- Electric-type driven reciprocating compressors
- Gas turbine-driven compressors
- Reciprocating engine-driven compressor
Inlet Gas Filtration Units
When natural gas enters a compressor station, it bears minute amounts of contaminants. Therefore, the incoming gas is directed through several filtration devices, i.e.:
- Filters
- Gas dehydration units
- Gas scrubbers
These devices eliminate impurities such as dirt, hydrocarbon liquids, suspended water vapor, and other particulate materials. At the same time, the collected hydrocarbon liquids are efficiently reinjected into the pipeline downstream of the compressor station. The dried gas is then conveyed to the next phase of the gas compression sequence.
Conclusion
Compressor stations are an integral division of a natural gas pipeline network that transports natural gas from independent-producing sites to end users. Without them, elevation differences, friction, and distance will severely impact the natural gas transported to end users across the country.
The natural gas will also be filled with impurities that will render it unusable unless it is purified. Compressor stations eliminate these impurities while boosting the pressure of the gas, restoring its flow rate and pressure loss.
From industry standards like Cooper Bessemer parts to Gemini compressor parts, we carry legacy components like packing, wiper cases, and more that you can count on. Contact us for our industry services!