Defibrator
Encyclopedia
The defibrator is a thermo mechanical pulping refiner in which the pulp material, such as wood chips, is ground in an environment of steam
between a rotating grinding disc (rotor) and a stationary disc (stator) each with radial grooves that provides the grinding surface. Wood chips are fed into the centre and are broken down as the centrifugal force pushes them towards the circumference of the discs where the grooves are finer to produce wood fibre
. The size of the refined fibres can to some extent be controlled by altering the distance between the discs where a closer distance produces finer fibres but also requires higher grinding force. The capacity per machine is largely determined by the speed of the rotor, well above 1000 rpm.
engineer Arne Asplund
filed a patent on a method to defibrate wood chips. As opposed to the Masonite
-method, the defibrator-method (also known as the Asplund-method) uses pressurised steam
to soften the wood chips, then grinding discs to pull the wood fibres apart. This grinding unit is what Asplund called the defibrator. It became the key product of his company, AB Defibrator. The Defibrator trademark is now held by Metso
.
Steam
Steam is the technical term for water vapor, the gaseous phase of water, which is formed when water boils. In common language it is often used to refer to the visible mist of water droplets formed as this water vapor condenses in the presence of cooler air...
between a rotating grinding disc (rotor) and a stationary disc (stator) each with radial grooves that provides the grinding surface. Wood chips are fed into the centre and are broken down as the centrifugal force pushes them towards the circumference of the discs where the grooves are finer to produce wood fibre
Wood fibre
Wood fibres are usually cellulosic elements that are extracted from trees, straw, bamboo, cotton seed, hemp, sugarcane and other sources.The end paper product dictates the species, or species blend, that is best suited to provide the desirable sheet characteristics, and also dictates the required...
. The size of the refined fibres can to some extent be controlled by altering the distance between the discs where a closer distance produces finer fibres but also requires higher grinding force. The capacity per machine is largely determined by the speed of the rotor, well above 1000 rpm.
History
In 1931 the SwedishSweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
engineer Arne Asplund
Arne Asplund
Dr. Arne Asplund invented the Defibrator pulping refiner and the defibrator-method for pulping wooden chips in 1930s...
filed a patent on a method to defibrate wood chips. As opposed to the Masonite
Masonite
Masonite is a type of hardboard invented by William H. Mason.-History:Masonite was invented in 1924 in Laurel, Mississippi, by William H. Mason. Mass production started in 1929. In the 1930s and 1940s Masonite was used for many applications including doors, roofing, walls, desktops, and canoes...
-method, the defibrator-method (also known as the Asplund-method) uses pressurised steam
Steam
Steam is the technical term for water vapor, the gaseous phase of water, which is formed when water boils. In common language it is often used to refer to the visible mist of water droplets formed as this water vapor condenses in the presence of cooler air...
to soften the wood chips, then grinding discs to pull the wood fibres apart. This grinding unit is what Asplund called the defibrator. It became the key product of his company, AB Defibrator. The Defibrator trademark is now held by Metso
Metso
Metso Corporation was created in 1999 through the merger of Valmet and Rauma and is headquartered in Helsinki, Finland. Metso is a global supplier of process industry machinery and systems as well as know-how and aftermarket services...
.