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.

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 which includes 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 also 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.

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 which includes 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 also 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.

A method for suppressing sedimentation of suspended substances 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 method for suppressing sedimentation of suspended substances 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.

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 for controlling paper making includes monitoring (302) a surface level of a fibrous suspension in a storage, and identifying (303) that the surface level has decreased so that at least one emptying criterion is met and thereafter identifying that the surface level has increased so that at least one refilling criterion is met, and responsively to the identifying that the surface level has increased so that the at least one refilling criterion is met, starting to dose a biocide agent into the fibrous suspension entering the storage. A corresponding apparatus and computer program are disclosed.

A method for controlling paper making includes monitoring (302) a surface level of a fibrous suspension in a storage, and identifying (303) that the surface level has decreased so that at least one emptying criterion is met and thereafter identifying that the surface level has increased so that at least one refilling criterion is met, and responsively to the identifying that the surface level has increased so that the at least one refilling criterion is met, starting to dose a biocide agent into the fibrous suspension entering the storage. A corresponding apparatus and computer program are disclosed.