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Howden's Mecahnical Vapor Recompression mission …to be the World’s Leading Applications Engineer for Vapor Compressors.
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Howden understands the unique process, aerodynamic, mechanical, and operations requirements of MVR applications, which differ from most any other application for rotating machinery industry, and as such, you can rely on Howden to be your trusted adviser to help you secure the optimum MVR vapor compressor solution.
Mechanical Vapor Compression reduces the energy used in the evaporation process by up to 90% compared with conventional systems. It works by reusing the heat energy contained in the vapor. This energy would otherwise be wasted. In a typical falling film evaporation plant the feed liquid enters the top of a vertical chamber called a Calandria. The liquid is dispersed across a large number of vertical tubes as it flows downwards it tends to form a film on the inside of the tube. Between the top and the bottom sections of the Calandria there is a sealed area where the tubes pass through a jacket of high temperature vapor. This section acts as a heat exchanger. As the hot vapor condenses on the outside of the tubes, it releases latent heat which raises the temperature of the feed liquid inside the tubes. By the time the feed liquid leaves the bottom of the tube, much of the water has been evaporated off leaving a concentrated viscous liquid. The water which has been evaporated off leaves the tubes as vapor. In the bottom section of the Calandria, some of the concentrated liquid gathers and can be drawn off. The hot mixture passes into a cooler chamber called the Separator where more of the concentrated liquid falls to the bottom to be drawn off and the vapor rises to the top. This vapor now contains most of the energy that was initially fed into the system. The ExVel turbo fan sucks the vapor from the Separator and re-compresses it, raising the pressure and so increasing the temperature to the point where the vapor can once again be used as a source of heat. The ExVel unit is extremely robust, gas tight turbo fan ideally suited to the pressure, temperatures and volumes of the MVC evaporation process. At it's heart is an ultra high speed impeller with a tip velocity of over 1000 Km/h, faster than the speed of a jet airliner. The ExVel rotor probably has the highest tip velocity of any welded impeller ever manufactured. The re-heated vapor can then be fed back into the Calandria to provide the heat energy required to evaporate more feed liquid as it passes down the tubes. The Mechanical Vapor Compression process is a highly energy efficient and cost effective way of retaining and reusing the latent heat contained in the vapor. Energy that would otherwise be wasted. Once the process has been started and brought up to temperature, the only energy input required is the electricity to drive the ExVel Turbo fan.