Abstract: A wet scrubber control system is configured with a pH sensor and a conductivity sensor in the return solution, and with a conductivity sensor in the feed solution. Concentration of the scrubbing agent within the feed solution is determined using the conductivity of the feed solution, corrected by subtracting a bias therefrom. The bias is established by first measuring the concentration of scrubbing agent in the return solution using the pH sensor. An expected conductivity of the return solution is then looked-up. The bias is set as the difference between the expected conductivity of the return solution and a measured conductivity of the return solution.

Abstract: A method for regulating the sodium carbonate concentration of a green liquor in the dissolving tank of the Kraft recovery process by measuring the conductivity of the green liquor from the dissolving tank, measuring the conductivity and flow rate of a weak wash solution being added to the green liquor in the dissolving tank, using these measurements to determine the sodium carbonate concentration of the green liquor in the dissolving tank, and adjusting the volume of the weak wash solution being added to the dissolving tank in response to changes in the concentration of sodium carbonate in the green liquor so as to maintain the concentration of sodium carbonate in the green liquor at a predetermined, preferably constant, level.

Abstract: An improved electrode cleaning system for an electrochemical sensor is disclosed. The improved electrode cleaning system includes a flexible wiper blade which is biased against a flat wiping surface formed by electrodes having a flat detection surface and a collar placed around the electrodes to prevent particulates from depositing between the electrodes. The collar is secured to the sensor by a recessed screw which also serves as a common electrical ground. The flexible blade preferably has two wiping portions for alternately wiping the electrodes and the common ground screw.