A method and a device for producing nanofibrillar cellulose

A method for producing nanofibrillar cellulose, wherein cellulose based fiber material in dispersion is processed for separating fibrils, the method comprising:

• a first step where the fiber material is supplied to a disperser, where it flows through several counter-rotating rotors in such a way that the fiber material is repeatedly subjected to shear and impact forces by the effect of different counter-rotating rotors, and a second step, where the fiber material obtained from the first step is supplied to a homogenizer, where it is subjected to homogenization by the effect of pressure.

A device for producing nanofibrillated cellulose from cellulose-based fiber material, comprising

• a disperser comprising an inlet and outlet for fiber material and between the inlet and outlet, several counter-rotating rotors configured to subject fiber material dispersion repeatedly to shear and impact forces by the effect of different counter-rotating rotors,
• a homogenizer comprising an inlet and outlet for fiber material and between the inlet and outlet, a narrow through-flow gap, said homogenizer further comprising means configured to create pressure in fiber material dispersion before said through-flow gap to cause shearing and impact forces on the fiber material dispersion flowing through said through-flow gap,
• the outlet of the disperser being connected to the inlet of the homogenizer.