A method of pulping wastepaper includes providing a pulping vessel with a rotor and at least one flow sensor adapted to measure slurry flow within the pulping vessel. The pulping vessel is charged with wastepaper and water to form a slurry, the amounts of wastepaper and water being present such that the slurry has consistency in the range of from 10% to 30%. The wastepaper charge in the pulping vessel is pulped at a pre-selected power level while monitoring poloidal slurry flow in the pulping vessel; and from time-to-time, water may be added to the pulping vessel when the poloidal flow falls below a predetermined lower threshold flow value in order to reduce viscosity and thereby restore poloidal flow within the pulping vessel. Doppler velocimetry is a preferred method of monitoring pulp flow. In a particularly preferred construction the rotor has a variable power drive. The inventive method is especially useful for making high quality, high brightness furnishes from wastepaper which varies from batch to batch.

A method of pulping wastepaper includes providing a pulping vessel with a rotor and at least one flow sensor adapted to measure slurry flow within the pulping vessel. The pulping vessel is charged with wastepaper and water to form a slurry, the amounts of wastepaper and water being present such that the slurry has consistency in the range of from 10% to 30%. The wastepaper charge in the pulping vessel is pulped at a pre-selected power level while monitoring poloidal slurry flow in the pulping vessel; and from time-to-time, water may be added to the pulping vessel when the poloidal flow falls below a predetermined lower threshold flow value in order to reduce viscosity and thereby restore poloidal flow within the pulping vessel. Doppler velocimetry is a preferred method of monitoring pulp flow. In a particularly preferred construction the rotor has a variable power drive. The inventive method is especially useful for making high quality, high brightness furnishes from wastepaper which varies from batch to batch.

Methods and systems are provided for dewatering an aqueous cellulosic pulp slurry or mat of cellulosic fibers or sludge. The method includes adding at least one anionic surfactant and at least one amide of a carboxylic acid to cellulose containing material to form a treated material and then dewatering the material. Besides effective dewatering, the present invention also provides foam control such as, but not limited to, the suppression of foam. Pulp products containing the treatment compounds are also described.

The disclosure relates to the technical field of dissolving pulp preparation, and particularly relates to a method for producing acetate grade dissolving pulp utilizing poplar residual slabs. The method comprises the following steps: adding an auxiliary agent for prehydrolysis, performing a Soda/AQ cooking I segment, performing a Soda/AQ cooking II segment, performing OpD.sub.QE.sub.PP bleaching and performing enzyme coprocessing, thereby preparing high-purity high-reactivity poplar residual slab acetate grade dissolving pulp. In the method, used chemicals are clean and environmental friendly, and production process is clean.

The present invention relates to a method for bleaching an unbleached or pre-bleached paper pulp comprising at least the following consecutive steps: a) preparing an unbleached or pre-bleached paper pulp having a pH of at least 8, b) bringing the paper pulp obtained at the end of step a) into contact with chlorine dioxide, c) when the pH of the paper pulp obtained from step b) is lower than 10, adding at least one Brnsted base to the paper pulp, d) adding hydrogen peroxide to the paper pulp obtained at the end of step c), e) maintaining the paper pulp obtained at the end of step d) in a first bleaching tower, f) optionally, adding sulphuric acid to the paper pulp obtained at the end of step e) and maintaining the obtained paper pulp in a second bleaching tower, the method dispensing with the need for a step of washing the paper pulp before the end of step e), and, if applicable, before the end of step f).

A bleaching apparatus comprises a measurement chamber has a first substance, the amount of the first substance in the measurement chamber being known. A dosing unit inputs a second substance to the measurement chamber for causing a chemical reaction between the first substance and the second substance, one of the first substance and the second substance being chlorine dioxide and another of the first substance and the second substance being filtered sample from pulp slurry of a pulp process. At least one sensor performs detection of a property known to depend on the chemical reaction between the first substance and the second substance as a function of time. A data processing unit determines chemical demand of chlorine dioxide for washing loss in a bleaching sub-process on the basis of at least one value in the detected property within a known period of time after the input of the second substance.

An apparatus comprising a chamber enclosing a flow path of a first fluid and having a second inlet arranged downstream of the first inlet for receiving a second fluid. The apparatus further comprises a vertically adjustable throttle body an end portion comprising three parts, the first part being upstream of the second part, the third part being downstream of the second part, wherein, in an operating position, the second inlet is upstream of the third part of the throttle body and downstream of the first inlet and wherein the first part and the third part of the end portion are adapted to achieve a higher flow rate than the second part.

The method disclosed relates to production of regenerated fiber from cellulose-containing plant species, in the textile sector. In particular, the method relates to obtaining water-soluble regenerated cellulose fiber using high or low purity cellulose raw material isolated from the wild plant species of Calluna Vulgaris.

A method of pulping wastepaper includes providing a pulping vessel with a rotor and at least one flow sensor adapted to measure slurry flow within the pulping vessel. The pulping vessel is charged with wastepaper and water to form a slurry, the amounts of wastepaper and water being present such that the slurry has consistency in the range of from 10% to 30%. The wastepaper charge in the pulping vessel is pulped at a pre-selected power level while monitoring poloidal slurry flow in the pulping vessel; and from time-to-time, water may be added to the pulping vessel when the poloidal flow falls below a predetermined lower threshold flow value in order to reduce viscosity and thereby restore poloidal flow within the pulping vessel. Doppler velocimetry is a preferred method of monitoring pulp flow. In a particularly preferred construction the rotor has a variable power drive. The inventive method is especially useful for making high quality, high brightness furnishes from wastepaper which varies from batch to batch.

In a process for producing bleached mechanical woodpulp, said process comprising the steps of a) delaminating comparatively large particles of wood, which have optionally been pretreated with chemicals and/or water, into modified particles of wood, b) grinding the modified particles of wood from a) in one or more refiners, c) optionally treating the stalk obtained in step b) with oxidative or reductive bleaching agents, a composition Z is present during step a) and/or step b), said composition Z comprising one or more of the following components (Z1) to (Z3): a salt of dithionous acid H.sub.2S.sub.2O.sub.4 (Z1), a dithionous acid or dithionous acid derivative generator compound (Z2), a salt of sulfurous acid (sulfite) plus sodium tetraborohydride (Z3) and also optionally additives (Z4).