Method and apparatus for evaluating repair and remediation alternatives for heat exchangers

1. A method for evaluating simultaneously the effects of multiple, interdependent heat-exchanger degradation modes for a heat exchanger of a power plant in the context of a series of alternative heat-exchanger remediation strategies that include individual options for remedying one or more of the degradation modes, the method comprising:

receiving probabilistic time-varying predicted future progressions of heat exchanger performance metrics for a plurality of alternative heat-exchanger remediation strategies, wherein the probabilistic time-varying predicted future progressions are based on a single, integrated probabilistic analysis of the effects of multiple, interdependent heat-exchanger degradation modes, the performance metrics including:

a secondary side operating pressure of the heat exchanger,

a heat-transfer efficiency of the heat exchanger,

a fraction of defective components within the heat exchanger that are subject to one or more heat-exchanger degradation modes, and

an electrical power output of the plant;

receiving probabilistic time-varying predicted future progressions of financial metrics describing the accumulated financial benefit of each of the plurality of alternative heat-exchanger remediation strategies; and

selecting and implementing one of the plurality of alternative heat-exchanger remediation strategies based on the received probabilistic time-varying predicted future progressions of the heat exchanger performance metrics, wherein the time-varying predicted future progressions of heat-exchanger performance metrics for a plurality of alternative heat-exchanger remediation strategies account for routine post-outage heat-transfer transients that result from operating the plant in accordance with each of the plurality of alternative heat-exchanger remediation strategies, and

wherein implementing the selected one of the plurality of alternative heat-exchanger remediation strategies includes performing at least one of the following acts:

chemical cleaning,

applying at least one dilute chemical,

lancing tube sheet sludge,

in-bundle water-jet lancing,

tube bundle flushing,

ultrasonic energy cleaning,

adding a polymeric dispersant,

changing secondary water chemistry,

repairing a defective heat-exchanger tube by plugging,

repairing a defective heat-exchanger tube by sleeving,

lowering a primary fluid temperature,

repairing at least one tube moisture separator component; or

replacing at least one tube moisture separator component.

2. The method of claim 1 , wherein:

one of the plurality of alternative heat-exchanger remediation strategies includes a modification of a valve of a high-pressure turbine of the power plant, wherein the turbine is operatively connected to the heat exchanger; and

another of the plurality of alternative heat-exchanger remediation strategies does not include the modification of the valve.

3. The method of claim 1 , wherein:

one of the plurality of alternative heat-exchanger remediation strategies includes an implementation of a feedwater heater bypass configuration; and

another of the plurality of alternative heat-exchanger remediation strategies does not include an implementation of a feedwater heater bypass configuration.

4. The method of claim 1 , wherein:

one of the plurality of alternative heat-exchanger remediation strategies includes a change to the chemistry of water in the secondary plant system; and

another of the plurality of alternative heat-exchanger remediation strategies does not include a change to the chemistry of water in the secondary plant system.

5. The method of claim 1 , wherein one of the plurality of alternative heat-exchanger remediation strategies includes adding zinc to a primary coolant associated with the heat exchanger, and wherein the time-varying predicted future progression of heat-exchanger performance metrics for the one of the plurality of alternative heat-exchanger remediation strategies accounts for one or more effects of an addition of zinc to the primary coolant.

6. The method of claim 1 , wherein the financial metrics account for forced outages associated with the plurality of alternative heat-exchanger remediation strategies.

7. The method of claim 1 , wherein the financial metrics account for mid-cycle outages associated with the plurality of alternative heat-exchanger remediation strategies.

8. The method of claim 1 , further comprising selecting and implementing one of the plurality of alternative heat-exchanger remediation strategies based on the received time-varying predicted future progressions of financial metrics.

9. The method of claim 1 , wherein at least one of the plurality of alternative heat-exchanger remediation strategies includes at least one of the following options for remedying tube deposit heat-transfer fouling:

full-height chemical cleaning at at least one specific time and/or frequency,

full-height chemical cleaning at a different time and/or frequency than a full-height chemical cleaning according to a different one of the plurality of alternative heat-exchanger remediation strategies,

partial-height chemical cleaning at at least one specific time and/or frequency,

partial-height chemical cleaning at a different time and/or frequency than a partial-height chemical cleaning according to a different one of the plurality of alternative heat-exchanger remediation strategies,

at least one dilute chemical application at at least one specific time and/or frequency,

at least one dilute chemical application at a different time and/or frequency than at least one dilute chemical application according to a different one of the plurality of alternative heat-exchanger remediation strategies,

tube sheet sludge lancing at at least one specific time and/or frequency,

tube sheet sludge lancing at a different time and/or frequency than a tube sheet sludge lancing according to a different one of the plurality of alternative heat-exchanger remediation strategies,

in-bundle water jet lancing at at least one specific time and/or frequency,

in-bundle water jet lancing at a different time and/or frequency than an in-bundle water-jet lancing according to a different one of the plurality of alternative heat-exchanger remediation strategies,

tube bundle flushing at at least one specific time and/or frequency,

tube bundle flushing at a different time and/or frequency than a tube bundle flushing according to a different one of the plurality of alternative heat-exchanger remediation strategies,

ultrasonic energy cleaning at at least one specific time and/or frequency,

ultrasonic energy cleaning at a different time and/or frequency than an ultrasonic energy cleaning according to a different one of the plurality of alternative heat-exchanger remediation strategies,

polymeric dispersant addition,

other secondary water chemistry changes, and

combinations thereof.

10. The method of claim 1 , wherein at least one of the plurality of alternative heat-exchanger remediation strategies includes at least one of the following options for remedying heat-exchanger tube corrosion and wear degradation:

repairing defective heat-exchanger tubes by plugging,

repairing defective heat-exchanger tubes by sleeving,

reducing the rate of future occurrence of degraded tubes by lowering the primary fluid temperature,

implementing a full-height chemical cleaning at one or more specific times,

implementing a full-height chemical cleaning at a different specific time than a full-height chemical cleaning according to a different one of the plurality of alternative heat-exchanger remediation strategies,

implementing a partial-height chemical cleaning at a specific time,

implementing a partial-height chemical cleaning at a different specific time than a partial-height chemical cleaning according to a different one of the plurality of alternative heat-exchanger remediation strategies, and

combinations thereof.

11. The method of claim 1 , wherein at least one of the plurality of alternative heat-exchanger remediation strategies includes at least one of the following options for remedying tube support plate broached hole blockage:

implementing a full-height chemical cleaning at one or more specific times,

implementing a full-height chemical cleaning at a different specific time than a full-height chemical cleaning according to a different one of the plurality of alternative heat-exchanger remediation strategies,

implementing at least one dilute chemical application at at least one specific time and/or frequency,

implementing at least one dilute chemical application at a different time and/or frequency than a dilute chemical application according to a different one of the plurality of alternative heat-exchanger remediation strategies,

in-bundle water-jet lancing at at least one specific time and/or frequency, and

in-bundle water-jet lancing at a different time and/or frequency than an in-bundle water-jet lancing according to a different one of the plurality of alternative heat-exchanger remediation strategies.

12. The method of claim 1 , wherein at least one of the plurality of alternative heat-exchanger remediation strategies includes at least one of the following options for remedying tube support plate material degradation:

implementing a full-height chemical cleaning at one or more specific times,

implementing a full-height chemical cleaning at a different specific time than a full-height chemical cleaning according to a different one of the plurality of alternative heat-exchanger remediation strategies,

implementing a partial-height chemical cleaning at a specific time,

implementing a partial-height chemical cleaning at a different specific time than a partial-height chemical cleaning according to a different one of the plurality of alternative heat-exchanger remediation strategies,

implementing at least one dilute chemical application at at least one specific time and/or frequency,

implementing at least one dilute chemical application at a different time and/or frequency than a dilute chemical application according to a different one of the plurality of alternative heat-exchanger remediation strategies,

in-bundle water-jet lancing at at least one specific time and/or frequency, and

in-bundle water-jet lancing at a different time and/or frequency than an in-bundle water-jet lancing according to a different one of the plurality of alternative heat-exchanger remediation strategies.

13. The method of claim 1 , wherein at least one of the plurality of alternative heat-exchanger remediation strategies includes at least one of the following options for remedying tube moisture separator component material degradation:

weld repairs,

separator component replacement,

at least one chemical cleaning at a different time and/or frequency than a chemical cleaning according to a different one of the plurality of alternative heat-exchanger remediation strategies, and

at least one in-bundle water-jet lancing at a different time and/or frequency than an in-bundle water jet lancing according to a different one of the plurality of alternative heat-exchanger remediation strategies.

14. The method of claim 1 , wherein at least one of the plurality of alternative heat-exchanger remediation strategies includes at least one of the following options for remedying one or more heat-exchanger degradation modes:

changing the primary fluid temperature;

changing a secondary plant structure such as a turbine;

changing a valve;

implementing a feedwater heater bypass configuration at a time that differs from an implementation of a feedwater heater bypass configuration according to a different one of the plurality of alternative heat-exchanger remediation strategies;

replacing the heat exchanger at one or more predetermined times;

replacing the heat exchanger at a time that differs from a time of replacement of the heat exchanger according to a different one of the plurality of alternative heat-exchanger remediation strategies;

changing the secondary water chemistry; and

combinations thereof.

15. The method of claim 1 , wherein at least one of the plurality of alternative heat-exchanger remediation strategies includes implementing a thermal power uprate to increase plant electrical power output.

16. The method of claim 1 , wherein the time-varying predicted future progressions of heat exchanger performance metrics include predicted metrics for different probabilities of occurrence.

17. The method of claim 1 , wherein the time-varying predicted future progressions of financial metrics include predicted metrics for different probabilities of occurrence.

18. The method of claim 1 , further comprising:

receiving a time-varying predicted future progression of heat exchanger performance metrics for a first alternative heat-exchanger remediation strategy that includes replacing the heat exchanger at a first time;

receiving a time-varying predicted future progression of financial metrics describing the accumulated financial benefit of the first alternative heat-exchanger remediation strategy;

receiving a time-varying predicted future progression of heat exchanger performance metrics for a second alternative heat-exchanger remediation strategy that includes replacing the heat exchanger at a second time that differs from the first time; and

receiving a time-varying predicted future progression of financial metrics describing the accumulated financial benefit of the second alternative heat-exchanger remediation strategy.

19. The method of claim 1 , wherein the heat exchanger comprises a heat exchanger of a nuclear power plant.

20. The method of claim 1 , wherein the receiving of time-varying predicted future progressions of financial metrics comprises receiving time-varying predicted future progressions of financial metrics based, at least in part, on different power plant lifetimes.

21. The method of claim 1 , wherein the evaluation of the effects of multiple, interdependent heat-exchanger degradation modes comprises an evaluation of at least two of the following degradation modes:

tube deposit heat-transfer fouling,

tube corrosion and wear,

support plate broached hole blockage,

tube support plate material degradation, and

moisture separator component material degradation.

22. The method of claim 1 , wherein said implementing one of the plurality of alternative heat-exchanger remediation strategies includes performing at least one of the following acts:

remedying tube deposit heat-transfer fouling, wherein said remedying of tube deposit heat-transfer fouling includes performing at least one of the following acts: full-height chemical cleaning, partial-height chemical cleaning, at least one dilute chemical application, tube sheet sludge lancing, in-bundle water-jet lancing, tube bundle flushing, ultrasonic energy cleaning, polymeric dispersant addition, and secondary water chemistry changes,

remedying heat-exchanger tube corrosion and wear degradation, wherein said remedying of heat-exchanger tube corrosion and wear degradation includes performing at least one of the following acts: repairing defective heat-exchanger tubes by plugging, repairing defective heat-exchanger tubes by sleeving, reducing the rate of future occurrence of degraded tubes by lowering the primary fluid temperature, implementing a full-height chemical cleaning, and implementing a partial-height chemical cleaning,

remedying tube support plate broached hole blockage, wherein said remedying of tube support plate broached hole blockage includes performing at least one of the following acts: implementing a full-height chemical cleaning, implementing at least one dilute chemical application, in-bundle water-jet lancing,

remedying tube support plate material degradation, wherein said remedying of tube support plate material degradation includes performing at least one of the following acts: implementing a full-height chemical cleaning, implementing a partial-height chemical cleaning, implementing at least one dilute chemical application, in-bundle water jet lancing, and

remedying moisture separator component material degradation, wherein said remedying of tube deposit heat-transfer fouling includes performing at least one of the following acts: making weld repairs, replacing a separator component, at least one chemical cleaning, and at least one in-bundle water jet lancing.

23. A computer-implemented method of evaluating simultaneously the effects of multiple, interdependent heat-exchanger degradation modes for a heat exchanger of a power plant in the context of a series of alternative heat-exchanger remediation strategies that include individual options for remedying one or more of the degradation modes, the method being implemented in a computer comprising electronic storage and one or more physical processors configured to execute one or more computer program modules, the method comprising:

calculating probabilistic time-varying predicted future progressions of heat exchanger performance metrics for a plurality of alternative heat-exchanger remediation strategies by evaluating the effects of multiple, interdependent heat-exchanger degradation modes in a single, integrated probabilistic analysis, the performance metrics including:

a secondary side operating pressure of the heat exchanger,

a heat-transfer efficiency of the heat exchanger,

a fraction of defective components within the heat exchanger that are subject to one or more heat-exchanger degradation modes, and

an electrical power output of the plant;

calculating probabilistic time-varying predicted future progressions of financial metrics describing the accumulated financial benefit of each of the plurality of alternative heat-exchanger remediation strategies; and

selecting and implementing one of the plurality of alternative heat-exchanger remediation strategies based on the probabilistic time-varying predicted future progressions of the heat exchanger performance metrics,

wherein implementing the selected one of the plurality of alternative heat-exchanger remediation strategies includes performing at least one of the following acts:

chemical cleaning,

applying at least one dilute chemical,

lancing tube sheet sludge,

in-bundle water-jet lancing,

tube bundle flushing,

ultrasonic energy cleaning,

adding a polymeric dispersant,

changing secondary water chemistry,

repairing a defective heat-exchanger tube by plugging,

repairing a defective heat-exchanger tube by sleeving,

lowering a primary fluid temperature,

repairing at least one tube moisture separator component; or

replacing at least one tube moisture separator component,

wherein the time-varying predicted future progressions of heat-exchanger performance metrics for a plurality of alternative heat-exchanger remediation strategies account for routine post-outage heat-transfer transients that result from operating the plant in accordance with each of the plurality of alternative heat-exchanger remediation strategies.

24. The method of claim 23 , wherein evaluating the effects of multiple, interdependent heat-exchanger degradation modes comprises evaluating at least two of the following degradation modes:

tube deposit heat-transfer fouling,

tube corrosion and wear,

support plate broached hole blockage,

tube support plate material degradation, and

moisture separator component material degradation.

25. A method for evaluating the progression of heat-exchanger tube deposit heat-transfer fouling in the context of a series of alternative heat-transfer fouling remediation strategies, in a single, integrated probabilistic analysis, the method comprising:

for each of a plurality of the alternative heat-transfer fouling remediation strategies, receiving calculated probabilities that routine, post-outage heat-transfer performance transients that affect the heat exchanger will result in plant thermal power reductions over a specified time period;

receiving calculated accumulated quantities of lost plant production associated with such thermal power reductions calculated over the specified time period; and

selecting and implementing one of the plurality of alternative heat-transfer fouling remediation strategies based on the received calculated probability and received calculated accumulated quantity of lost plant production,

wherein implementing the selected one of the plurality of alternative heat-exchanger remediation strategies includes performing at least one of the following acts:

chemical cleaning,

applying at least one dilute chemical,

lancing tube sheet sludge,

in-bundle water-jet lancing,

tube bundle flushing,

ultrasonic energy cleaning,

adding a polymeric dispersant,

changing secondary water chemistry,

repairing a defective heat-exchanger tube by plugging,

repairing a defective heat-exchanger tube by sleeving,

lowering a primary fluid temperature,

repairing at least one tube moisture separator component; or

replacing at least one tube moisture separator component.