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US 8,524,088 B2Granted
Method to inhibit scale formation in cooling circuits using carbon dioxide
AssigneeAmerican Air Liquide, Inc.
InventorsJeffrey E. Arbogast, Meenakshi Sundaram, Daniel D. Duarte
Life of this patent
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Abstract
Scaling is controlled in a cooling water system with CO2 based upon measurements of the cooling water's pH, alkalinity and Ca2+concentration.
Claims2
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 Ca2+concentration and alkalinity of the sample;
- d) calculating a setpoint pH based upon the selected scale index value and the measured Ca2+concentration and alkalinity;
- e) measuring a pH of the cooling water;
- and
- f) adding an amount of CO2 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 Ca2+concentration and alkalinity measurement device adapted and configured to perform said step of measuring the Ca2+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 Ca2+concentration and alkalinity from the Ca2+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 CO2 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 CO2 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 Ca2+concentration and alkalinity of the makeup water sample;
- calculating a second setpoint pH based upon the selected makeup water scale index value and the Ca2+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.
23 more elements
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 Ca2+concentration and alkalinity of the sample;
- d) calculating a setpoint pH based upon the selected scale index value and the measured Ca2+concentration and alkalinity;
- e) measuring a pH of the cooling water;
- and
- f) adding an amount of CO2 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 Ca2+concentration and alkalinity measurement device adapted and configured to perform said step of measuring the Ca2+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 Ca2+concentration and alkalinity from the Ca2+concentration and alkalinity measurement device to the controller;
- i) sending a signal corresponding to the measured pH from the pH probe to the one or more controllers, wherein said step of adding comprises:
- 1) determining with the controller whether or not CO2 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 CO2 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 alkalinity in the cooling water;
- determining an alkalinity setpoint to be maintained in the makeup water based upon the alkalinity desired in the cooling water and the alkalinity measured in the cooling water;
- measuring an alkalinity of the makeup water;
- and
- adding a mineral acid pH change agent to the makeup water based upon a measured makeup water alkalinity and the alkalinity setpoint to be maintained in the makeup water.
21 more elements
Dependencies are inferred from the claim text.