A. Ahlstrom Corporation

Matti Manninen

Reijo Vesala

Kari Peltonen

A method and apparatus allow large volumes of gas (at least about 10% by volume) to be mixed into a cellulosic fiber suspension having a consistency of about 8-25%. The mixing of ozone containing gas into the suspension is particularly desirable. The suspension is passed into the inlet of a mixer, gas is introduced into the mixer, and the gas and fiber suspension are homogenized by fluidizing the gas and suspension. The flow of suspension through the mixer is throttled so that the effect of the fluctuation and pressure between the inlet and outlet is minimized, and the homogeneously mixed gas and fiber suspension mixture is discharged from mixer outlet. The mixer may have a premixing zone in which the gas and suspension are fluidized to the floc level and the gas is evenly distributed throughout the suspension, then a homogenization zone in which the fiber suspension is fluidized to fiber or microfloc level and the gas is brought into contact with each fiber or microfloc, and then a maintenance zone in which the fluidization level is maintained high enough to prevent the generation of gas bubbles and the separation of gas from the suspension.

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Kotka, Finland

Matti Manninen