Verfahren und Vorrichtung zur automatischen Behandlung wässeriger Flüssigkeiten mit Kalk

摘要

In an arrangement for treating water with lime to obtain water of a predetermined quality, the conductances of the treated and untreated water is continuously measured and the lime feed is controlled in such a manner that any deviation of the measurements from a predetermined ratio is corrected. The conductivity cells 81, 82, Fig. 3, switch pump 63 to feed lime from hopper 60 to the upper compartment 26 of tank 10, Fig. 1, in accordance with the ratio of the measurements applied to the controller 80, the lime supply is terminated when the ratio exceeds 1, the minimum ratio prevailing at the point at which calcium bicarbonate and any magnesium salts present have been precipitated and increasing towards 1 as more lime is added. The lime is fed as a paste 50 lb. to 7 1/2 gallons, of water, which is mixed by depositing the lime on the surface of the water. Excess lime in the treated water can be removed by recarbonation with flue gas or liquid carbon dioxide to a selected pH value, or by adding a further known quantity of water. Rain water and lime paste are fed into the top compartment 26 through inlet 49 together with a slurry of previously precipitated calcium carbonate from outlet 54 in the lower compartment 27 and rain water is also injected through inlet 47 near a rotor 42 which is coupled to a shaft 40 driven by a motor 36. The effluent from the upper compartment flows through a conduit 30 wherein further rain water is added by pipe 51 to reduce the excess of lime, and passes through holes 22 in a partition 20, a stirrer 44 maintaining previously precipitated calcium carbonate in suspension, and a rotor 43 stirring a coagulant admitted through a pipe 68. The coagulated water is passed through apertures 22 to a clarification chamber 12, clarification being enhanced by the downward deflection of the water by a baffle 70. The treated water is taken off by a conduit 73 in a launder 71. Reference is made to differences of pH in various zones. An alternative arrangement in which the reactor is centrally arranged in the clarifier is described with reference to Fig. 4, not shown. Quantitative examples of water impurities and added lime together with conductance readings are given. A sparger ring 100 is provided beneath rotor 43 for the injection of flue gas or liquid carbon dioxide.