TH97893A - Control systems for industrial water systems and methods for their use - Google Patents

Abstract

The DC60 is a control system for industrial water systems that utilizes various datasets and models to determine optimal control actions that maximize corrosion/scaling/pollution inhibition and particle dispersion values while minimizing water and chemical treatment costs. This system can automate a wide range of processes under various conditions, ensuring the achievement of various performance objectives, operating robustly under diverse and unmeasurable disturbances, and achieving minimal solution delivery.

Claims (27)

1. The control system for monitoring and controlling industrial water systems consists of: (a) measurement of at least one operating variable and at least one measured result value representing a safety margin close to the performance bound; (b) detection of at least one dynamic transfer function value between at least one measured result value and at least one operating variable value; (c) determination of indices derived from the current and future values of at least one measured result and indices derived from the current and future values of at least one operating variable; (d) at each sampling time, the processor maximizes the index of at least one measured result and minimizes the index of at least one operating variable, and detects the current and future values of at least one operating variable; and (e) at each sampling time, the current value of at least one operating variable within the water system is used. 2. The control system of claim 1 where the industrial water system is a circulating system. 3. The control system of claim 2 where the industrial water system is a cooling tower system or a hot water boiler system. 4. Patent 1 control system where the operating variables consist of chemical feed rate, manufactured water flow rate, downward blowing flow rate, circulating water flow rate, and a combination of the above. 5. The control system of claim 1, where the measured results comprise a safety margin close to the limit of capability, water source composition, water system composition, and a combination of the aforementioned. 6. The control system of claim 1, where a safe margin approaching the demonstrated boundary value is detected using a heat exchanger, corrosion probe, or a combination of the aforementioned. 7. The control system of claim 1, where the boundary value representing capability is the boundary on the other side where corrosion, scaling, and contamination occur. 8. The control system of claim 1, where the dynamic transfer function is related to the measured result at time t to the measured result and operating variable at a time prior to time t. 9. The control system of claim 1, whereby the measured result at future time t is calculated from the measured result and operational variables at a prior time t. 10. The control system of claim 1, where both indices are functions of the present and future values of the operational variable. 11. The control system of claim 1 in which the controller, at each sampling time, detects the current and future values of the operating variable and uses the current value of the operating variable. 12. A control system for monitoring and controlling industrial water systems comprising: a) Defining a special classification of measured results as a safety margin close to the capability bound; b) Operating the industrial water system under conditions where the safety margin is close to the capability bound; c) Quantifying the effects of unmeasurable disturbances in terms of safety margin reduction; d) Identifying the dynamic transfer function from measured disturbances to measured results; e) Identifying the dynamic transfer function from operating variables to measured results; f) Identifying the independence of the safety margin on measured results relative to water chemistry; g) Defining a capability index as a weighted sum of current and future measured results, and a cost index as a sum of water and chemical treatment costs derived from weighted current and future operating variables, taking mandatory accounting into account on measured results and operating variables; h) Maximizing the capability index value at each sampling time. The objectives are: i) to minimize the cost index and identify the current and future values of the operating variables; and i) to utilize the current values of the operating variables within the water system. 13. Control system of claim 12 where the industrial water system is a recirculating system. 14. The control system of claim 13 where the industrial water system is a cooling system or a hot water boiler system. 15. The control system of claim 12 where unmeasurable and measurable disturbances include changes in the composition of the water source, water loss from the circulation system, changes in the production rate, changes in the environment, changes in the system structure and a combination of the aforementioned. 16. The control system of claim 12, where the operating variables consist of the chemical feed rate, the generated water flow rate, the downward blowing water flow rate, the recirculating water flow rate, and a combination of the aforementioned. 17. The control system of claim 12, where the measured results comprise a safety margin close to the limit value representing capability, the composition of the water source, v'8Nxitdv[ of the water system, and a combination of the aforementioned. 18. The control system of claim 12, where a safe margin approaching the demonstrated boundary value is detected using a heat exchanger, corrosion probe, or a combination of the aforementioned. 19. The control system of claim 12, where the boundary values representing capability are divided on the other side where corrosion, scaling and contamination occur. 20. The control system of claim 12, where a safe margin near the boundary value representing capability is detected using a heat exchanger so that the surface temperature is (formula) higher than the hottest area in the water system and no scaling/decontamination is detected, then (formula) is defined as the safe margin near the scaling/decontamination boundary of the water system. 21. The control system of claim 12, where a safe margin near the boundary value is detected using a corrosion detector, so that the potential difference (formula) is between the cathode and anode electrodes and no corrosion is detected, then (formula) is determined to be the safe margin near the boundary of corrosion of the water system. 22. The control system of claim 12 in which procedure f) the independence of the safe margin on the measured results relative to water chemistry can be estimated by the ratio of the change in the safe margin to the change in the measured results relative to water chemistry within a particular area. 23. The control system of claim 12, where in step d) the dynamic transfer function is related to the measured result at time t until the measured result and the measured disturbance at a time prior to time t. 24. The control system of claim 12, where in step e) the dynamic transfer function is related to the measured result at time t until the measured result and the operating variable at time t prior to time t. 25. The control system of claim 12, where the measured result at a future time t is calculated from the measured result, measured disturbances, and operational variables at a time prior to time t. 26. The control system of claim 12, where both indices are functions of the present and future values of the operational variable. 27. The control system of claim 12 in which the controller, at each sampling time, detects the current and future values of the operating variable and uses the current value of the operating variable.