Oil and gas
25th Jan 2022

How a natural gas compressor station works

Natural gas compressor stations are a critical part of natural gas pipelines.

As the gas moves through the pipeline, distance and friction cause it to lose pressure. Compressor stations placed at key points over the length of the pipeline ensure there’s enough pressure to keep the gas moving efficiently from point A to point B.

In this blog, we’ll look at how a natural gas compressor station works, and why the right oil and gas filtration systems are vital to ensuring they work effectively.

How a natural gas compressor station works

A natural gas compressor station provides additional pressure to a gas pipeline to keep the gas flowing over long distances. 

There are two main types of natural gas compressor stations:

Reciprocating compressor stations

The gas enters the compressor through a cylinder at the base. A piston then pushes the gas onward at a higher pressure. Valves at the compressor’s outlet act like a diaphragm, ensuring the gas flows in only one direction.

Centrifugal compressor station

These are used for larger pipelines. Gas enters a shaft with a set of constantly spinning impellers, much like an aeroplane turbine. The blades propel the flow of the gas from one side, increasing the pressure with each set of impellers until it’s forced through the pipeline.

Discover the six key challenges of process filtration and how to overcome them. Read now.

Why filters are a crucial component of gas compressor stations

Gas moving through the pipeline collects various solids and liquids. These can cause damage when they reach the compressor station. If your compressor station isn’t performing optimally or requires maintenance, it creates significant risks and loses profit.

In reciprocating compressors, solids can build up in valves, disrupting the flow of gas. Solids could also get into the cylinder and piston, causing serious damage. Cleaning or replacing damaged parts costs labour, materials, and revenue.

Liquids like water or oil create issues for compressors as well. If enough of it gets into the piston, it might blow off a piston head which could seriously injure operators.

To minimise these risks, you need to remove solids and liquids from the gas before it reaches the compressor. This is where filters have an important role to play, both upstream processing and downstream processing.

Upstream – scrubber and cartridge filters

Before gas reaches a reciprocating compressor, it will typically move through two types of filters – scrubber filters and cartridge filters.

A lot of liquid can condense inside a pipeline. This can accumulate to the point where gas will push anywhere between 100-500 litres of liquid through the pipe. If all this liquid gets to a cartridge filter at once, it could destroy it. Scrubber filters help prevent this risk.

Scrubber filters trap and remove the larger liquid particles from the gas before it gets to the cartridge filter. Then the cartridge filter removes the fine liquids and solids to ensure the gas is as clean as possible before it moves to the compressor.

Downstream – coalescing filters for reciprocating compressors

Reciprocating compressors require large quantities of lubricating oil due to their metal parts frequently coming into contact. Depending on the size of the compressors, they might need dozens of litres of oil every day to run efficiently.

Some of this oil will be carried out with the gas, adding to the liquids that the next compressor in the pipeline has to handle. Downstream coalescing filters work to remove the oil from the gas. These filters force the gas through an element, causing the oil in the gas to coalesce into droplets. The droplets are captured in the filter media and drained into the bottom of the two sections of the vessel.

Lubricating oil can be a high-cost resource. If it’s disappearing down the pipeline, you’ll have to keep refilling it. Coalescing filters let you recover that oil, reuse it, and make significant savings.

Optimise your gas pipeline with experienced filtration partners

Having the right filtration systems in place is key to keeping your gas pipeline working effectively. If liquids and solids get into your gas compressors, it can cause damage, downtime, lost revenue, and health and safety risks.

That’s why it’s important to work with filtration experts who understand the unique challenges that oil and gas companies face. A partner with industry experience will help optimise your filtration processes to ensure your compressor stations are safe, efficient, and generating profit.

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