Process for discharging impurities from a hydrocyclone and a hydrocyclone

A process for discharging impurities from a suspension containing paper fibers using a hydrocyclone comprising a radially inner area, the process comprising:

• adding a diluting liquid into the suspension in the radially inner area of the hydrocyclone, the diluting liquid being added in a flow direction opposite to an axial discharge direction of the impurities,
• wherein the adding comprises adding a flow of the diluting liquid with only a swirl whose resulting flow rate vector is defined by a peripheral speed (Vu) and axial speed (Vax) at an edge of a jet, the resulting flow rate vector having an angle (α) relative to an axial axis of no greater than approximately 30°.

A process for discharging impurities from a suspension containing paper fibers using a hydrocyclone comprising a radially inner area, the process comprising:

• adding a diluting liquid into the suspension in the radially inner area of the hydrocyclone, the diluting liquid being added in a flow direction opposite to an axial discharge direction of the impurities,
• wherein the adding comprises adding the diluting liquid via a ring-shaped jet.

A process for discharging impurities from a suspension containing paper fibers using a hydrocyclone comprising a radially inner area, the process comprising:

• adding a diluting liquid into the suspension in the radially inner area of the hydrocyclone, the diluting liquid being added in a flow direction opposite to an axial discharge direction of the impurities,
• wherein the adding comprises adding the diluting liquid into a center portion of the radially inner area with the aid of an injector, the injector drawing in liquid from a ring-shaped area around an addition point.

A process for discharging impurities from a suspension containing paper fibers using a hydrocyclone comprising a radially inner area, the process comprising:

• adding a diluting liquid into the suspension in the radially inner area of the hydrocyclone, the diluting liquid being added in a flow direction opposite to an axial discharge direction of the impurities,
• wherein the adding comprises adding the diluting liquid at an axial speed of at least approximately 4 m/s.

A process for discharging impurities from a suspension containing paper fibers using a hydrocyclone which includes a separating cone having a narrowest point and an addition point disposed in an area of the narrowest point, the process comprising:

• adding the diluting liquid into the suspension via the addition point,
• wherein the diluting liquid is added without swirl in a flow direction opposite to an axial discharge direction of the impurities.

A process for discharging impurities from a suspension containing paper fibers using a hydrocyclone which includes a separating cone having a narrowest point and an addition point disposed within the separating cone, the process comprising:

• adding the diluting liquid into the suspension via the addition point,
• wherein the diluting liquid is added without swirl in a flow direction opposite to an axial discharge direction of the impurities.

A process for discharging impurities from a suspension containing paper fibers using a hydrocyclone which includes a separating cone having a narrowest point and an addition point adjustably positioned in the separation cone, the process comprising:

• adding the diluting liquid into the suspension via the addition point,
• wherein the diluting liquid is added without swirl in a flow direction opposite to an axial discharge direction of the impurities.