Abstract: A method and an arrangement for treating stock formed of recycled fiber. The method comprises treating the stock in screen means and a flotation cell means, and screening the stock into accept and reject. Reject from the screening is directed to a mechanical dispergator and a dispersed reject is formed of it.

Abstract: A method and an arrangement for treating stock formed of recycled fibre. The method comprises treating the stock in screen means and a flotation cell means, and screening the stock into accept and reject. Reject from the screening is directed to a mechanical dispergator and a dispersed reject is formed of it.

Abstract: A measuring device is provided that includes a camera, and an image-processing unit and a fractionating pipe. The receives a sample from recycled fibre pulp of a recycled fibre process and arranges the particles of the flowing sample in accordance with particle size. The measuring device processes the sample as at least two fractions according to particle size. The camera images at least one fraction. The image-processing unit receives images imaged by the camera and measures at least one parameter of an added substance in at least one imaged fraction.

Abstract: A method for optimizing the debarking result of logs debarked in a debarking drum, especially logs of mutually approximately the same size and of the same wood species, in such a way that wood losses remain as small as possible at the same time as the control values of the debarking drum are selected to be such that the debarking degree of the logs debarked in the debarking drum is of the desired order. The amount of bark remaining on the logs in the log flow discharged from the debarking drum and the amount of damaged logs in the said log flow are measured. At the same time as the amount of bark remaining on the logs is maintained at a desired level, the amount of damaged logs is kept as low as possible in such a way that the filling degree of the debarking drum is lowered whenever the amount of damaged logs is observed to increase.

Abstract: The invention relates to a method of controlling quality of pulp. Pulp formed in mechanical defibering of wood is screened into at least two fractions, the accept that has passed the screening phase being forwarded for further use and the reject that did not pass the screening being removed from the screening phase. The invention comprises determining flow amount and consistency of the pulp supplied to the screening phase and, correspondingly, of the reject removed therefrom, and calculating a passage ratio of the reject and the supplied pulp by means of the flow amounts and consistency values verified through the measurement, and adjusting the screening phase according to said passage ratio.

Abstract: A method for controlling the quality of pulp. Pulp produced by mechanical defibering of wood is screened to provide at least two fractions, of which the accept that has passed the screening phase is carried forward for use and the reject that has not passed the screening is removed from the screening phase. The consistency of the reject that is to be removed from the screening is measured and the consistency value thus obtained is used for controlling the defibrator to adjust the quality of the accept.

Abstract: The invention relates to a method of controlling quality of pulp. Pulp formed in mechanical defibering of wood is screened into at least two fractions, the accept that has passed the screening phase being forwarded for further use and the reject that did not pass the screening being removed from the screening phase. The invention comprises determining flow amount and consistency of the pulp supplied to the screening phase and, correspondingly, of the reject removed therefrom, and calculating a passage ratio of the reject and the supplied pulp by means of the flow amounts and consistency values verified through the measurement, and adjusting the screening phase according to said passage ratio.

Abstract: A method for controlling the quality of pulp. Pulp produced by mechanical defibering of wood is screened to provide at least two fractions, of which the accept that has passed the screening phase is carried forward for use and the reject that has not passed the screening is removed from the screening phase. The consistency of the reject that is to be removed from the screening is measured and the consistency value thus obtained is used for controlling the defibrator to adjust the quality of the accept.

Abstract: The invention relates to a method for measuring gas content in a fluid, such as papermaking pulp or coating paste, and to a gas content measuring device. Pressure variations generated by a pump, for instance, are to occur in the fluid. Travel time, phase and/or attenuation of the microwave signal (20) are measured with the gas content measuring device while the signal (20) penetrates through the fluid (13), and the gas content is determined on the basis of changes in travel time, phase and/or attenuation of the microwave signal (20) caused by pressure variations of the fluid (13).