Screw Compressors

Howden screw compressors are manufactured to exacting standards and supplied to distributors worldwide. In addition to supplying bare shaft units we provide complete screw compressor systems engineered for specific installations.

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WRV Compressors


WRV Compressors represent the bench mark against which industry comparison is made for both gas and refrigeration applications.

Features and benefits of WRV compressors:

  • Plain shell type journal bearings – long operational life span
  • Double wall construction – suitable for high pressure applications
  • Optional material of construction – flexibility to match project specifications
  • Oil injected seal bearing construction – high quality gas seal from simple construction
  • Range of capability – the most comprehensive range of capacity available
  • Installed compressors – more than 20,000 WRV compressors have been installed worldwide

All WRV range compressors are of double wall construction and utilise white metal, sleeve type journal bearings with pressurised shaft seal. A full range of vi options from 2.1 to 5.8 is offered for each compressor while slide valve capacity control is a standard feature on all compressors.

Process Refrigeration have many options available other than standard designs:

  • Conditioning version with reduced oil flow for dense gases such as R22
  • Mirror version for reverse rotation with double ended motor drive and two stage design
  • Higher pressure version for high discharge pressure
  • Extra high discharge design
  • Tilting pad thrust bearing design e.g. to comply with API 619
  • Steel casings for high pressure or to match specification
  • Nodular cast iron design for specific project specification
 

XRV Compressors

Howden Compressors have specifically developed the XRV range of compressors for the commercial refrigeration market.

There are many features and benefits of XRV compressors:

  • Ease of installation, ideal for horizontal separator applications
  • Use of roller bearings, no oil pump for over 90% of installations
  • Variable vi available with either adjustable or fully automatic vi system
  • Stepless capacity control, combined with variable vi, gives maximum energy saving
 

Variable Volume Ratio

Two forms of variable volume control are available:

  • Adjustable volume ratio (MVi)
  • Automatic Variable Volume Ratio (AVi)

Care is taken during compressor selection to ensure that the correct volume ratio is selected by comparison to the chosen operating conditions.

However, in many instances the compressor is selected against peak conditions which may only apply for a very few days each year.

While it is essential to select hardware which is capable of operating in the most extreme environment, it does not follow that the compressor will necessarily always perform at the highest possible efficiency.

The Howden variable Vi concept, coupled to slide valve capacity control, offers alternative methods of controlling capacity and volume ratio to suit site conditions.

Where the pressure ratio across the compressor is consistently high or changes in pressure ratio are infrequent (e.g. the change from winter to summer conditions) then the MVi manually adjustable system will be entirely satisfactory.

With lower pressure ratios or where condensing conditions vary frequently, the Howden automatic control AVi system is ideal.