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ExVel® Turbo Fans
ExVel® turbo fans are designed for customer specific applications and built by an experienced engineering team using a well developed, modular component concept. Each fan is custom designed to be the cost-effective and reliable solution for air and gas movement with a differential pressure demand up to 1 bar (15PSI).

Key Benefits

Designs can be supplied for vacuum or over pressure systems
Manufactured to high standards from a variety of materials to meet specific process conditions - even in the most demanding and corrosive environments.
Readiness for advanced adjustable speed control (VSD / VFD)
Customer specific tailored design
With drastically improved performance (closer to a centrifugal compressor) the ExVel turbo fan comes with significantly lower investment costs and trouble-free operation. ExVel(R) vapour compressors provide great value for operators of modern day evaporation plants.

ExVel® Turbo Fans Versatile custom designed units for process-critical applications

ExVel® Turbo Fans For process air, process gas and vapor compression

ExVel® Turbo Fans For Mechanical Vapor Compression (MVC)

Every ExVel(R) turbo fan is designed for a specific application using a modular component concept. The ExVel(R) casing is gas tight steel fabrication with strong machined flanges.

Standard Features

Bearings can be antifriction or sleeve bearing
Shaft seal comes in various high-tech arrangements - the most suitable is chosen for the customer process and installation
Our welded impeller design allows the use of a variety of materials to meet specific conditions - for example, high strength steel, stainless steel and nickel alloys, Our various impeller designs meet the requirements of the most demanding industrial applications with industry leading efficiency and operational stability,
A vast variety of instrumentation and monitoring options are available to meet demanding industry and customer specific requirements. All instrument cables can be wired in flexible conduit to terminal box.
Water injections and drainage - the turbo fan can be equipped with spraying nozzles for cleaning and continuous de-superheating purposes.

Optional Features

To meet your complex project specific requirements the product may include the features below, and can be compliant with the relevant pressure vessel codes.

API673 options
Control panel option
Gear set
Variable speed options (VSD / VFD or steam turbine)
Inlet guide vane option
Hydrodynamic bearings
Acoustic enclosure option
Complete skid with wiring
Integrated lubrication system

Detailed specifications
The use of the latest advanced fluid dynamic modelling, finite element analysis, novel welding techniques and latest bearing concepts have allowed for a high performance improvement over the years.

  • Motor powers up to 6 MW
  • Depending on the inlet water vapour conditions the maximum ΔT can go from 6 to 10oC in a single stage

Combining two or three MVC systems in series will allow a ΔT increase up to 23oC

  • In air applications pressure increase can reach, and in some cases, exceed 1 bar
  • Volume flow can reach, and depending on gas conditions, can be over 160 m3/s


One of the most important applications for ExVel Turbo Fans is MVC (mechanical vapour compression), also known as mechanical vapour recompression (MVR).
Evaporation and distillation are the most energy demanding unit operations in the industry, and several methods have been developed to reduce the energy required in these processes, including Multiple Effect Evaporation (MEE) and Thermal Vapour Compression (TVC) but typically the most energy efficient approach will be using Mechanical Vapour Compression (MVC).  In the MVC process, the vapour compressor is the key component in providing the mass and energy transfer required for evaporation. Moreover, the MVC loop does not, contrarily to MEE’s and TVC’s need a heat sink, and is therefore the optimal solution where cooling water is at a premium. The mechanical work required to drive the vapour compressor is provided either by an electric motor, a back pressure steam turbine or an internal combustion engine (diesel, natural gas, methane etc.).

Usually the feed stream is evenly distributed onto a heat transfer surface of the evaporator heat exchanger. Evaporation takes place when the feed stream is heated to boiling by a heat source on the distillate side of the heat exchanger. In the MVC cycle, the water vapour drawn off the feed stream is compressed in the vapour compressor to a pressure level where it can be condensed and reused as heating medium.  The vapour condenses on the distillate side of the heat exchanger and can be reused as such as process water, and after a conditional polishing used as boiler feed water. The concentrated solution will be further processed, when necessary, in a dryer or a crystallizer or disposed of.

As a part of the MVC process, ExVel can be used in the following industries:

Power generation: to prepare boiler feed water from blow-off of effluent
Mining: concentration of mine water
Metals: in MVC evaporators and evaporative crystallizers to concentrate leachates and metal salts in hydrometallurgical refining.
Sugar industry: to concentrate clarified juice in MVC evaporators. The technology is especially attractive for new installations with co-generation and for de-bottlenecking.
Pulp and Paper: to concentrate effluents from semi-chemical and chemical wood pulping for chemical recovery and for closing the process water loop.
Iron and Steel: to concentrate waste water streams and leachates in the Iron and Steel Industries.
Chemicals: to concentrate chemical solutions for transport, further processing in crystallizers or dryers.
Pharmaceutical: to produce sterile water and to recover VOC’s from aqueous effluents.
Renewable Fuels: to concentrate stillage in bioethanol plants. 
SAGD: to concentrate effluent from the SAGD process while recovering the distillate as boiler feed water.
Dairy Industry: to concentrate dairy products. The applications include skim milk, whole milk, cheese whey, casein whey, whey proteins, milk proteins etc.
Food processing (incl. sweeteners): used in MVC evaporators and evaporative crystallizers to concentrate liquid food products; fruit and berry juices, sweetener solutions and protein hydrolysates.

Additionally ExVel turbo fans can be used for any air or gas circulation, pressurising or exhaust fans in a variety of industries.
Spare Parts
Howden Turbo Fans is committed to supporting both EPC/OEM’s and end-users through the turbo fan’s entire life cycle. Our skilled staff provides a professional service concept: commissioning, inspections and measurements on site, replacement fans or parts for the installed product base and accessories such as motors, dampers, frequency converters and lubrication oil units. Delivering original or equivalent spare parts on time is an essential part of our service. In addition to repair and maintenance we carry out refurbishment and modernization projects. Just get in touch.

If you have an urgent technical support request and need to speak to one of our aftermarket team immediately you can contact us using our on-call 24/7 service number +358 50 446 3350.

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