The present invention relates to a process for manufacturing a fibre web, such as paper, board, tissue or the like. In the process bleached cellulose-containing fibres are suspended into process water in order to prepare a fibre stock, which comprises residual hydrogen peroxide. The process comprises at least one pulp storage tower through which the fibre stock is transferred before it is formed into a fibrous web and dried. Zinc ions are introduced to the fibre stock or one of its constituents to maintain the amount of residual hydrogen peroxide in the fibre stock at or above a predetermined threshold level after at least one pulp storage tower.

The present invention relates to a process for manufacturing a fibre web, such as paper, board, tissue or the like. In the process bleached cellulose-containing fibres are suspended into process water in order to prepare a fibre stock, which comprises residual hydrogen peroxide. The process comprises at least one pulp storage tower through which the fibre stock is transferred before it is formed into a fibrous web and dried. Zinc ions are introduced to the fibre stock or one of its constituents to maintain the amount of residual hydrogen peroxide in the fibre stock at or above a predetermined threshold level after at least one pulp storage tower.

A method includes forming an aqueous fibre suspension including cellulosic fibres from one or more raw material flows, and applying at least one chemical and/or physical control measure to the aqueous fibre suspension or at least one of its raw material flows for control of microbial activity in the aqueous fibre suspension or the raw material flow before an inlet of an intermediate residence entity. In this manner a starting ORP value for the aqueous fibre suspension is obtained. The aqueous fibre suspension is in the intermediate residence entity at least a minimum delay time. A final ORP value is measured for the aqueous fibre suspension after an outlet of the intermediate residence entity before the formation of the fibrous web. An ORP difference value between the starting ORP and final ORP values is calculated. Finally, the aqueous fibre suspension is formed into a fibrous web and dried.

A method includes forming an aqueous fibre suspension including cellulosic fibres from one or more raw material flows, and applying at least one chemical and/or physical control measure to the aqueous fibre suspension or at least one of its raw material flows for control of microbial activity in the aqueous fibre suspension or the raw material flow before an inlet of an intermediate residence entity. In this manner a starting ORP value for the aqueous fibre suspension is obtained. The aqueous fibre suspension is in the intermediate residence entity at least a minimum delay time. A final ORP value is measured for the aqueous fibre suspension after an outlet of the intermediate residence entity before the formation of the fibrous web. An ORP difference value between the starting ORP and final ORP values is calculated. Finally, the aqueous fibre suspension is formed into a fibrous web and dried.

A method for suppressing sedimentation of suspended substances ef the present invention is a method for suppressing sedimentation of suspended substances in water at the bottom of a tank disposed in a water system in papermaking equipment, comprising a step of blowing an oxygen-containing gas into the water, for stirring and aeration; a step of detecting a change with time in existence states of the suspended substances in the tank by the stirring and the aeration; and a control step of feeding at least one of an oxygen-containing gas and a slime control agent to the tank based on the detection result to suppress the sedimentation of the suspended substances in the tank.

A pulp transportation system is adapted for transporting a pulp among a pulp-supply machine and a plurality of forming machines, and includes a pump unit, a first pipe unit, a second pipe unit and a valve unit. The pump unit is adapted for urging the pulp to flow. The valve unit is operable to control flow of the pulp through the first pipe unit and the second pipe unit, such that the flow of the pulp is convertible between a pulp-supply state, in which the pulp flows out from the pulp supply machine into at least one of the forming machines, and a pulp-return state, in which the pulp flows out from at least one of the forming machines into the pulp supply machine.

A pulp transportation system is adapted for transporting a pulp among a pulp-supply machine and a plurality of forming machines, and includes a pump unit, a first pipe unit, a second pipe unit and a valve unit. The pump unit is adapted for urging the pulp to flow. The valve unit is operable to control flow of the pulp through the first pipe unit and the second pipe unit, such that the flow of the pulp is convertible between a pulp-supply state, in which the pulp flows out from the pulp supply machine into at least one of the forming machines, and a pulp-return state, in which the pulp flows out from at least one of the forming machines into the pulp supply machine.

The bin arrangement is for collecting and discharging smaller ligno-cellulosic material. The bin has a transition part from a circular section of the bin and downwardly to a rectangular section with a long and short side of the rectangular section. The transition part could be built with few wall segments, thus needing less welding. Two rotary pocket feeders, each with at least one shaft extending parallel to the long side, are arranged directly under the rectangular section, enabling a uniform feed from the bin. The use of two rotary pocket feeders with this design directly under the bin does not destroy the even feed of material through the bin part, which otherwise is experienced from using conventional feed screws that feed material in a transverse direction from the bin outlet. The bin does not need to have a complex bin design which converges to a small circular inlet to a conventional rotary pocket feeder.

An arrangement and a method for controlling a gas flow separated from a suspension of medium consistency pulp. The pulp is treated in a pulp treatment apparatus including a first pump and a second pump, wherein the second pump is a degassing centrifugal pump provided with a degassing system including a degassing conduit in which a degassing valve is arranged for regulating a pressure difference between an inlet of the second pump and the degassing conduit. The degassing system further includes a pressurized degassing vessel working under overpressure and having an inlet and an outlet, wherein the outlet of the vessel is connected to a pressure control valve for maintaining a desired overpressure in the vessel.

An arrangement and a method for controlling a gas flow separated from a suspension of medium consistency pulp. The pulp is treated in a pulp treatment apparatus including a first pump and a second pump, wherein the second pump is a degassing centrifugal pump provided with a degassing system including a degassing conduit in which a degassing valve is arranged for regulating a pressure difference between an inlet of the second pump and the degassing conduit. The degassing system further includes a pressurized degassing vessel working under overpressure and having an inlet and an outlet, wherein the outlet of the vessel is connected to a pressure control valve for maintaining a desired overpressure in the vessel.