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Oil & Gas Ejectors

Transvac is a leading supplier of Ejectors to the Oil & Gas industry for both topside, FPSO and subsea applications.

Transvac Gas Ejector installed on a Shell Expro platform for boosting production
of a low pressure gas Well using energy from a high pressure gas well.

Typical applications include:-

Gas Ejectors

  • Boosting production of low pressure (LP) gas Wells
  • Minimising condensate loading
  • Unloading of shut-in wells
  • Flare gas recovery / flare gas elimination
  • Boosting capacity of mechanical Compressors
  • Compression of overhead gas to MEA scrubbers
  • Gas compression between two stages of a two stage Combustor
  • Compression of waste gas into a flare header system

Oil Ejectors

  • Boosting production of low pressure (LP) oil Wells
  • Unloading shut-in Wells

Liquid Jet Compressors

  • Boosting production of low pressure (LP) Wells

Steam Ejectors

  • Vacuum degassing
  • Vacuum drying
  • Steam pressure boosting
  • Sulphur pit ventilation

Liquid Jet Pumps

  • Pumping, washing and pressure boosting sand slurries from separators
  • Mixing barite powder into water for mud mixing

Send us your requirements using our TRANSVAC Product Enquiry Forms.

 

Design
 

Principle of Operation

Transvac Gas Ejector

Ejectors have no moving parts and use high pressure fluid to compress low pressure Fluid to an intermediate level.

For further information see 'HOW EJECTORS WORK' in the FAQ section.

Transvac has been manufacturing Venturi and Fluid Jet Systems to our own designs for 30 years. This knowledge and experience is invaluable because it enables Transvac to produce Ejectors using the very latest Ejector design and construction techniques.

As a fully integrated modern in-house Ejector manufacturer we maintain full control over the process and mechanical design, supply of raw materials, manufacturing, scheduling and testing.

Each Ejector is custom designed specifically to suit a customers individual process requirements to ensure maximum operating efficiency.

Transvac can also undertake a design study to assess the viability of using an Ejector for a specific application.

Mechanical Design

Standard TRANSVAC Ejectors are designed and manufactured in accordance with recognised national and international design codes such as ASME VIII Div. 1, PD5500, ASME B31.3, Stoomwezen etc. with full non-destructive testing. All Transvac’s design and manufacturing processes are quality assured and certified to BS EN 9001. Transvac is also accredited to module H of the PED (Pressure Equipment Directive - EU Standard).

Advantages of Ejectors
 
Transvac Universal-Design Ejector supplied to Shell Expro to boost production of a LP Well
  • No moving parts
  • Negligible Maintenance
  • Proven reliability
  • Easy to install
  • Simple to control
  • Low cost & weight
  • Short pay-back
  • Low noise levels
  • Handles solids, two phase flow and liquid slugs without damage
  • Project cost significantly less than mechanical compressor
  • Performance easily modified to suit depleting Well conditions
  • Top-side or sub-sea installation

 

Applications
 

Energy from a High Pressure (HP) Well, normally wasted by choking, can be used by a Transvac Ejector to:-

  • Boost production of Low Pressure (LP) Wells
  • Prevent shut-in of LP Wells under high export (MP) pressure
  • Reduce tendancy for Wells to load with condensate
  • Increase total field recovery
  • Ensure line velocities are within erosion constraints
  • Limit sand production

If a suitable HP Well is available nearby, the pressure energy that is normally wasted across a choke could be used to drive an Ejector to reduce the head pressure of the LP Well, thereby bringing it back into production, even at times of high demand. In the case of nearly and fully shut-in Wells, the increase in production rates can be significant since the P-Q curves are at their flattest in this region. (Small drop in pressure causes large increase in production).

The diagram shows the P-Q curve from a typical LP Well. The orange line represents the situation before the fitting of an Ejector (also called JET Compressor).

Using energy from a suitable high pressure source (a choked HP Well for example) an Ejector can be used to lower the pressure at the Well head of the LP Well. If the pressure reduction achieved by the Ejector at the Well head is ‘A’ on the diagram, then the increased production from the LP Well will be represented by ‘B’.

An added advantage is that by using an Ejector the total energy recovery from a LP Well can be increased by up to 25% additional revenue over the life of the well.

Low Pressure (LP) Gas Well Boosting

The diagram shows a typical arrangement for an Ejector application.

 

Transvac Universal Design Ejector supplied to Shell Expro
to boost production of LP Wells

Transvac Universal Design Gas Ejector supplied to Shell Expro
for boosting production of LP gas Wells and to minimise condensate loading

See Application Sheet GJC010
See Application Sheet GJC011

Send us your requirements using our TRANSVAC GAS EJECTOR Enquiry Form

Low pressure Oil Well Boosting

The diagram below shows a typical arrangement for an Oil Ejectors application.

 

Size 4 Gas Ejector

Send us your requirements using our Oil Ejector Enquiry Form

Transvac Patented Universal Design Gas Ejectors
 

  • Manufacture of internal components can be delayed until HP Well conditions are established. Manufacture of main pressure shell, not delayed.
  • Delay between Well completion and installation minimised
  • Internal components can be replaced to suit depleting Well conditions
  • Specialist skills not required to install new internals

The patented “Universal” Design ejector comprises an external pressure retaining shell, into which can be fitted easily-replaceable internal working components (i.e. the nozzle and the diffuser). This approach allowes the design and manufacture of the pressure retaining shell to proceed, before the new HP Well conditions are known. This part takes the longest time to manufacture. Once the new HP Well is completed and the actual conditions known, the internal nozzle and diffuser can then be designed and manufactured.

Thus, the delay between Well completion and installation of the Ejector can be minimised.

An added advantage of this design is that the pressure retaining envelope can be sized to accommodate nozzle and diffuser designs for anticipated future operating conditions. Consequently, as the Well depletes over time, a new nozzle and diffuser can be fitted into the existing shell to match the new operating conditions and so maintain production at optimum level with the minimum downtime and cost.

Boosting Capacity of Mechanical Compressors

Transvac Gas Ejectors can be used to increase the capacity of an existing mechanical compressor installation by changing the operating interstage pressure.

The Ejector can be installed immediately upstream of the first stage to achieve a volume reduction, thereby increasing capacity.

In some instances a mechanical compressor can be totally replaced by a Gas Ejector reducing energy costs and maintenance.

Send us your requirements using our Gas Ejector Enquiry Form

Flare Gas Recovery / Elimination

Traditionally in the Oil & Gas Industry, waste and surplus gas has been disposed of by flaring to atmosphere. Today this process is becoming increasingly unacceptable as the Industry progresses towards eliminating the emission of greenhouse gases into the atmosphere whilst simultaneously conserving energy.

Therefore, the demand for equipment that can safely and economically compress waste and surplus gas back into the production process is rapidly increasing.

Gas Ejector fitted with integral HP gas regulating Assembly

Transvac Gas Ejectors are ideally suited to this application because they employ high-pressure gas energy to entrain and compress waste and surplus gas to a pressure where the gas can be used in the process.

Alternative schemes could involve the use of a side stream taken from the discharge of the Gas-lift Compressors as the HP motive gas supply. Schemes in which the flare gas is compressed into the fuel gas system are also common.

Control of Flare Gas Ejectors

In these applications, it is not uncommon for the flowrate of the flare gas to vary and; if not controlled, the suction pressure created by the Gas Ejector will also vary. In order to maintain the desired pressure on the suction side of the GAS-JET Compressor, a number of standard control techniques are available.
These include:-

  • Recycling of gas from the discharge side of the Gas Ejector back into the suction (low pressure) side
  • Incorporation of an integral HP gas regulating assembly which varies the motive fluid consumed. (As shown in the photograph)

Sulphur Pit Ejectors

In processing crude oil into refined products such as petrol and motor oils, sulphur must be removed. This is done chemically and it results in a concrete pit containing molten sulphur which emits hydrogen sulphide and other noxious gases. These gases are vented to a burner to prevent them escaping to atmosphere.

Transvac Steam Ejectors are a reliable, simple and low cost method of entraining the gases and discharging them to the burner with a steam jacket is employed around the Ejector to prevent sulphur from precipitating out.

Transvac Steam Jet Thermocompressors are also used on sulphur recovery plants for recovering and compressing flash steam.

Pumping Sand Slurries from Separators

Transvac Liquid Jet Pump with ceramic internal parts

Transvac Eductors (also called Liquid Jet Pumps) are an ideal method of transporting sand slurries from Separators or Cyclones as part of a de-sanding / sand washing system for the Oil & Gas and allied industries.

Accumulated sand is normally fluidised; to ensure it will flow, using jets of water by-passed from the motive water supply, prior to entering the suction port of the Eductor.

Transvac sand slurry Eductors are manufactured as standard with ceramic motive water nozzles and ceramic throat inserts to resist abrasion. The body of the Eductor is available in 316L stainless steel, carbon steel, duplex steel or super duplex steel.

See Application Sheet SSJP010

 

Subsea Ejector Applications
 

Subsea

Typical applications include:-

  • Production boosting of low pressure (LP) or shut-in oil & gas wells
  • Sand slurry pumping from separators
  • Filter backwashing

Advantages

Ejectors offer a number of important advantages for subsea operation:-

  • No moving parts
  • Very low maintenance. Can be scheduled within planned maintenance activities
  • Proven reliability
  • Flexible operation
  • Simple to control remotely
  • Low cost
  • Low weight
  • Special materials available for long life (ceramics etc)
  • Handles solids, two phase flow and liquid slugs without damage
  • Project cost significantly less than mechanical devices

Production boosting of low pressure (LP) or shut-in oil & gas wells

All Ejector systems are custom designed to suit the Well operating conditions with one or a number of Ejectors installed in parallel for maximum operating flexibility. The systems are compact, use simple controls and can operate across a wide range of pressures and flows.

Gas Ejector System for Subsea operation

Filter Backwashing

Ejectors in this case called Liquid Jet Pumps can be used to back flush filters used as part of mechanical subsea pumping systems. To resist erosion from entrained solids the Liquid Jet Pump motive nozzle and throat would usually be made from high grade ceramics.

Transvac Liquid Jet Pump with ceramic internal parts...
Transvac Systems Ltd, Monsal House, Bramble Way, Alfreton, Derbyshire, DE55 4RH, England
Telephone: +44 (0)1773 83 11 00 Facsimile: +44 (0)1773 83 11 23 E-mail: sales@transvac.co.uk
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