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Waste Energy
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Waste Energy

Opportunities to drive Ejectors using existing or otherwise-wasted energy

Transvac has developed a range of Ejectors that use waste (free) energy usefully which help in the urgent drive to reduce energy costs and thereby carbon emissions.

 

Once a suitable source of high-pressure gas or liquid has been found there are many potential applications where an Ejector can be used as a reliable and robust gas Compressor.

 

Typical examples include:

 

  • Flare and Flash gas compression
  • Boosting production of low-pressure Wells (Gas, Oil or Multiphase)
  • Compressor replacement
  • De-bottlenecking Compressor trains
  • Unloading liquid from Wells
  • Increasing performance of existing Compressors

Compressor Recycle Opportunity

Waste or excess gas energy can be used to drive Ejectors. For example: High-pressure, gas energy from an existing mechanical Compressor that is normally wasted across an anti-surge valve when in recycle mode, can be used to drive a gas Ejector.

 

With globally 1000’s of existing mechanical Compressors in recycle with waste energy available, the opportunities to use waste energy usefully are vast.

 

There are other sources of available high-pressure gas that can be used to drive an Ejector including;

  • Compressor discharge gas
  • Export gas
  • Gas injection or lift gas
  • Gas from 1st or 2nd stage Separator

Using compressor recycle gas to drive an Ejector
Transvac's Ejector Test Facility

High Pressure Liquids Opportunity

In many oil & gas facilities, produced water, injection water, seawater, amine, multiphase or other high-pressure liquids can be used to drive an Ejector. Where an existing liquid stream is available, but at a lower pressure than required by the Ejector, a booster pump can be added to boost the pressure to drive an Ejector. High pressure liquids are simply ‘borrowed’ and typically returned back to the process.

 

Transvac continues to improve the operating efficiency of liquid driven Ejectors, meaning that even less liquid flow is required, when compared to older, less efficient traditional Ejector designs. This continual improvement makes more projects viable, especially when only small ‘slipstream’ flows from existing high-pressure pumps are available. This is of particular importance for facilities in remote or desert climates, where for example water usage is at a premium.

Liquid Driven Ejector to Boost Well Production

Award Winning Flare Gas Recovery Project

 

Transvac has applied this approach to a high-profile Flare Gas Recovery project in Saudi Arabia. The project utilised a slipstream of injection water to drive a Flare Gas Recovery Ejector. The Ejector entrained, compressed and recovered the otherwise-flared gas stream back into the Separator (WOSEP), where it was sent for processing. The Client is now looking to roll-out this approach at multiple other sites as a way to eliminate flaring by again utilising this available water stream.

 

More information on this award winning project can be found here.

Pressure Let-Down Opportunity

Rather than simply wasting pressure energy across a valve or similar let-down device, an Ejector can be driven (delivering the same pressure let-down), but performing a gas compression duty, for free! In some cases, the technique can also be used for Flare Gas Recovery

 

Well Revival / Well Boosting

Transvac has used this technique effectively in upstream oil & gas, where high pressure Wells are being choked. Rather than wasting the pressure energy across the choke valve, the Ejector nozzle becomes, in effect, a choke and uses the energy usefully. The available high-pressure energy is used to drive an Ejector to assist weak, low pressure wells – or even revive dead / shut-in wells!

How an Ejector can use a high pressure well to boost a low pressure well

Compressor Replacement

In a recent project in Saudi Arabia, a pressure let-down opportunity was identified at a gas and oil separation plant (GOSP), which operated with high- and low-pressure gas compression trains. Transvac was able to install an Ejector package which utilised the otherwise-wasted pressure energy, lost across a valve in the high-pressure (HPPT) stream, to entirely eliminate the low-pressure (LPPT) mechanical compressor. Not only does this Ejector package operate using existing waste energy, it eliminated the running costs and significant maintenance of the low-pressure compressor.