Patent ID: 8852402
Filing Date: 2014-10-07
Classification: D21H

Abstract:
1. A method for production of calcium carbonate in a target suspension of a fibrous web forming process of a fibrous web machine, the target suspension comprising at least one of virgin pulp suspension, recycled pulp suspension, additive suspension and solids-containing filtrate, wherein the calcium carbonate is produced in a reactor having a flow pipe transporting the target suspension and the reactor includes a first electrode in and extending in the flow pipe along a direction of the flow of the target suspension and a second electrode on or incorporated in a surface of the reactor adjacent the flow pipe and the second electrode extending the length of the flow pipe, wherein the first electrode and the second electrode are isolated from each other and each exposed to the target suspension in the flow pipe, the method comprising: injecting a chemical including at least one of carbon dioxide and lime milk through at least one injection mixer to said target suspension as said target suspension flows through the flow pipe of the reactor; allowing said chemical to react while in the target suspension to form calcium carbonate crystals, and inhibiting precipitation of the chemical or a reaction product of the chemical on the surface of or in the reactor by application of an electric or magnetic field to or proximate to the surface along a region of the surface adjacent to the reaction involving the chemical by: applying a direct current (DC) to the first electrode and the second electrode, wherein the polarity of the DC causes one of the first electrode and the second electrode to be a cathode and the other of the first electrode and the second electrode to be an anode, periodically switching the polarity of the DC such that one of the first electrode and the second electrode become the anode while switching the other of the first electrode and the second electrode becomes the cathode.