Abstract: A method for washing pulp in a multistage pulp washing operation involves controlling operating conditions so as to maximize the efficiency of the operation particularly in response to determination of the percent consistency off the discharge side of each drum washer. The major variables that are useful to control are vat dilution flow, drum speed, vat level set point, drainage aids or defoamers, press roll pressures, vacuum break position, and temperature of the last stage showers.

Abstract: In a pulp washing system where there is substantially constant average weight of pulp mat (on a dry pulp basis), washing uniformity is improved by controlling the weight per unit area of liquid alone or liquid and pulp combined in the pulp mat across its width to obtain a substantially constant distribution of selected property in the pulp mat across its width. This is accomplished by steps comprising determining the property in a plurality of selected locations across the width of the pulp mat and also the average value of the property across the width and controlling dilution liquid input into the headbox in response to the determination to produce of substantially constant distribution of the property across the width of the mat.

Abstract: Wash water input into a pulp washing system is controlled in response to measurements on a stream of output constituents of reduced transverse dimension compared to the transverse dimension of the washed pulp mat discharge stream from the pulp washing system. The measurements are conducted simultaneously across the entire width of the reduced dimension stream on all the washed pulp and water leaving the pulp washing system. The measurements are readily carried out using apparatus including means below said reduced dimension stream.

Abstract: Pulp washing efficiency at any given dilution factor and production rate is maximized by controlling washing surface speed in response to determination of total mass of product stream in weight per unit area on the surface and simultaneously controlling the rate of dilution liquid introduction in response to sensing of feed level in the container feeding the surface, thereby to obtain a substantially constant level of pulp in the feed and in the pulp mat formed on the washing surface which is to undergo washing and a substantially constant weight of pulp mat (on a dry pulp basis) per unit area on the washing surface.

Abstract: Control of pulp and water flow rates out of a bleaching tower in a multistage pulp bleaching process wherein each stage comprises a bleaching tower and a washing drum, comprises the steps of (a) measuring total weight of pulp composition per square meter on at least one washing drum and from such measurement and the speed of rotation and area of the washing drum surface and the consistency of pulp composition, determining the total weight per unit time of pulp and of water coming out of the bleaching tower previous to said washing drum, and (b) controlling the rate of pulp and water flow out of said previous tower based on the determination of the total weight per unit time of pulp and of water as determined in step (a), and (c) controlling the amount of bleaching chemical flow to the pulp going to any following stage to match the pulp flow rate as determined from the measurement of step (a) and the percentage of bleaching chemicals to be applied.

Abstract: A method of controlling the amount of a liquid shower flow introduced onto a slurry mat such as a pulp mat which is undergoing incomplete liquid separation on a vacuum filter drum. The flow rate of the liquid being discharged with the slurry mat is determined by a capacitance measurement which is taken after the slurry mat has passed to a point on the filter means where liquid separation no longer occurs. The shower flow is controlled by a correlation of the flow rate of the liquid in the slurry mat with the rate of slurry mat transfer from the vacuum filter drum and the necessary liquid shower flow as expressed by a dilution factor.The present control system may be combined with secondary apparatus to measure the flow rate and thickness of the total slurry mat in order to determine by correlation the slurry mat consistency, the rate of solid material production from the slurry mat and the amount of air contained in the slurry mat.

Abstract: This invention relates to a continuous method for determining the concentration of a chemical component in a fluid stream, using the heat of reaction or enthalpy as a measure of the concentration, when the chemical component whose concentration is to be determined is reacted with an appropriate reagent. The improvement of the present invention resides in the regulation of the temperature of the reagent stream to approximate the temperature of the reacted mixture product stream. An additional embodiment of the present invention shows the regulation of the temperature of the sample stream such that the final reacted mixture temperature will substantially equal or closely approximate the temperature of the reagent stream.