Skip to the main content.

1 min read

Tech Tip - Over/Under Compression in a Rotary Screw Compressor

Tech Tip - Over/Under Compression in a Rotary Screw Compressor

Tech Tip


Over/Under Compression in a Rotary Screw Compressor

TechTip

Screw compressors are a crucial part to the natural gas industry, and typically operate under wide variants of operating conditions in both gathering and process applications. Whether the compressor is experiencing pressure and volume fluctuations, temperature swings or changing gas composition, the screw compressor is a reliable piece of equipment that powers through operational swings without issue. However, this doesn’t mean that the compressor is operating as efficiently as it could be!

Optimization can result in significant power savings and/or reduce the potential for catastrophic failure. It is beneficial to analyse the performance at frequent intervals to ensure your screw compressors continues to operate without issue, at low cost. The most common method to optimize a screw compressor is by adjusting the Internal Volumetric Ratio (Vi). Adjustments to the Vi are recommended when the unit is experiencing over or under compression, or the internal discharge pressure exceeds the max allowable.

The following graphic allows you to visualize the relationship between pressures, Vi and gas composition to better understand the compression process, and the effects those variables have on power requirement. Note that the process highlighted in the graph is as follows:

  1. A volume of gas is captured in the rotors: (At Suction Pressure)
  2. The volume of gas is compressed in the rotors: (Increasing Pressure)
  3. The volume of gas is exposed to the discharge line and expelled: (At Discharge Pressure)

 

*Note that the graphic is conceptual, and does not account for partial loading due to the slide valve.

For questions regarding the performance of your screw compressors, please contact your Detechtion representative.

Evaluating for Power Savings in your Compressor Fleet

Evaluating for Power Savings in your Compressor Fleet

Enalysis offers a new and greatly improved user experience allowing customers to better identify, investigate and act on valuable opportunities for...

Read More
Achieve ESG Goals and Avoid Balance Sheet Blowback

Achieve ESG Goals and Avoid Balance Sheet Blowback

Global Health, Safety and Environment (HSE) teams are adapting their risk management and safety programs as guided by the industry’s budding ESG...

Read More
Managing by Exception and Reducing Emissions in the Oilfield

Managing by Exception and Reducing Emissions in the Oilfield

With each day that passes, the urgency to implement policies focused on combatting climate change grows. Federal and state governments are...

Read More