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.