Scale conditioning agents and treatment method

A method of conditioning and removing scale and deposits within a heat exchange system that utilizes at least one heat transfer liquid comprising:

• taking the heat exchange system out of service;
• providing within the heat exchange system an aqueous cleaning solution of a scale conditioning agent, the scale conditioning agent comprising a chelating agent, the chelating agent being present in the aqueous cleaning solution at a treatment concentration range higher than 1 weight percent and less than or equal to 2 weight percent,
• circulating the aqueous cleaning solution throughout the heat exchange system during a treatment period and, while circulating the aqueous cleaning solution;
• maintaining the temperature of the aqueous cleaning solution within a treatment temperature range;
• maintaining the pH of the aqueous cleaning solution within a treatment pH range that is higher than 9.0 and less than or equal to 11.0;
• and
• agitating the aqueous cleaning solution as it circulates through the heat exchange system during a least a portion of the treatment period;
• removing substantially all of the aqueous cleaning solution from the heat exchange system at the end of the treatment period;
• introducing replacement heat transfer liquid;
• and
• returning the heat exchange system to service,
• wherein the heat exchange system comprises a steam generator of a nuclear power plant.

A method of conditioning and removing scale and deposits within a heat exchange system that utilizes at least one heat transfer liquid comprising, in sequence, the steps of:

• taking the heat exchange system out of service;
• providing an aqueous cleaning solution of a scale conditioning agent within the heat exchange system, the scale conditioning agent comprising a chelant, a treatment concentration of the chelant in the aqueous cleaning solution in the heat exchange system being higher than 1 weight percent and less than or equal to about 2 weight percent, the aqueous cleaning solution having a pH higher than 9.0 and less than or equal to 11.0;
• removing substantially all of the aqueous cleaning solution from the heat exchange system;
• returning the heat exchange system to service,
• wherein the heat exchange system comprises a steam generator of a nuclear power plant.

A method of conditioning and removing scale and deposits within a heat exchange system that utilizes at least one heat transfer liquid comprising, in sequence, the steps of:

• taking the heat exchange system out of service;
• providing within the heat exchange system an aqueous cleaning solution of a scale conditioning agent, the scale conditioning agent comprising a chelant at a concentration in the aqueous cleaning solution that is higher than 0.034 moles per liter and less than or equal to 0.068 moles per liter, the aqueous cleaning solution having a pH that is higher than 9.0 and less than or equal to 11.0;
• removing substantially all of the aqueous cleaning solution from the heat exchange system;
• returning the heat exchange system to service,
• wherein the heat exchange system comprises a steam generator of a nuclear power plant.