Patent ID: 8524088

Claim:
A method for controlling scale formation in a cooling water system, said method comprising the steps of: a) selecting a desired scaling index value indicating a desired degree of scaling or absence of scaling in the cooling water system; b) obtaining a sample of cooling water from the cooling water system; c) measuring a Ca 2+ concentration and alkalinity of the sample; d) calculating a setpoint pH based upon the selected scale index value and the measured Ca 2+ concentration and alkalinity; e) measuring a pH of the cooling water; and f) adding an amount of CO 2 to the cooling water based upon the setpoint pH and measured pH; the method further comprising the steps of: g) providing operating an apparatus comprising: A) one or more controllers, written with an algorithm adapted to perform said step of calculating a setpoint pH, B) a Ca 2+ concentration and alkalinity measurement device adapted and configured to perform said step of measuring the Ca 2+ concentration and alkalinity of the sample, C) a pH probe adapted and configured to perform said step of measuring the pH of the sample; h) sending a signal corresponding to the measured Ca 2+ concentration and alkalinity from the Ca 2+ concentration and alkalinity measurement device to the controller; j) sending a signal corresponding to the measured pH from the pH probe to the controller, wherein said step of adding comprises: 1) determining with the controller whether or not CO 2 should be added to the cooling water system based upon whether the measured pH is higher than the setpoint pH, and 2) adding the amount of CO 2 based upon said step of determining, wherein the cooling water system includes a cooling tower, a basin adapted to receive cooling water from the cooling tower, and a heat exchange system adapted and configured to exchange heat between a hotter fluid and the cooling water and discharge the cooling water toward a cooling water inlet formed in the cooling tower, said method further comprising the steps of: discharging an amount of cooling water from the basin; adding makeup water to the cooling water system to replace the cooling water discharged from the basin; selecting a desired scaling index value indicating a desired degree of scaling or absence of scaling in the makeup water; obtaining a sample of cooling water from the makeup water; measuring a Ca 2+ concentration and alkalinity of the makeup water sample; calculating a second setpoint pH based upon the selected makeup water scale index value and the Ca 2+ concentration and alkalinity measured from the makeup water sample; measuring a pH of the makeup water; and adding an amount of mineral acid pH change agent to the makeup water based upon the second setpoint pH and the pH measured from the makeup water sample.