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What experience does ControlSoft bring to the control of Water Treatment or Wastewater Treatment problems?
Project for One of the Largest City Water Departments in the U.S.
Problems before MANTRA
- Residual chlorine control to a setpoint of 2 ppm
- Long retention time required, resulting in transportation delay (deadtime)
- Water flow fluctuations
- Multiple chlorine injection points
- Original variation 0.5 - 5.0 ppm
- Need to overdose chlorine to keep residual at 0.5 or higher at all times
Scope of the Project
- Over 35 chlorination stations on a WAN
- Central data collection on Emerson's Power & Water Solutions DCS
Solution provided by MANTRA
- Chlorine control to a setpoint of 1.5 ppm
- Model-based control with model-based feedforward compensation
- MANTRA Coordinated Controller achieves variation of 0.2 ppm around setpoint
Benefits of MANTRA
- Consistent chlorine content in drinking water
- Lower usage of chlorine (by more than 25%)
- Substantial savings in chlorine costs
Project for 90-Million-Gallons-Per-Day Water Supply Facility
Problems before MANTRA
- Chlorine discharge residual fluctuated because of seasonal water demands
- Manual adjustments by operators
- Transportation delays
- Low sampling rates
- Flow-proportional control enhanced oscillations
Scope of the Project
- Review the existing chlorination control schemes
- Recommend additional instrumentation to improve chlorination control
- Design an advanced control strategy for better chlorination control
- Implement and commission the project
Solution and Benefits of MANTRA
- Model-based control with model-based feedforward compensation
- Maintains the chlorine discharge residual constantly within +/- 0.1 ppm of the desired setpoint
Results
- MANTRA advanced chlorination control maintains the chlorine discharge residual constantly within plus or minus 0.1 ppm of desired setpoint.
Testimonial
When asked to compare the previous control system to the MANTRA solution, the plant operator
said, "They are as different as night and day."
For Large City Wastewater Treatment Plant
Problems before MANTRA
- Large chlorine contact basins with significant deadtime between injection and measurement
- A combination of operator manual and automatic control was used to maintain chlorine levels.
- Original wide variation of 1.25 mg/l to 2.5 mg/l
- Water flow fluctuations
Solution provided by MANTRA
- Lower chlorine control setpoint
- Model-based control with model-based feedforward compensation
- Fully automated control
Results
- MANTRA Coordinated Controller achieves variation of 1.0 - 1.5 mg/l
Actual Plant Trend Data Over Twenty-Four Hours
Benefits
- Much tighter control, an improvement of 90-140% of reduced chlorine variation, resulting in a lower residual setpoint
- Reduced long-term chemical usage
- Successfully alleviated faulty sensor readings
- The control system is easier to use and to maintain.
Testimonial
"The operator, at a minimum, needed to make two adjustments during the day to compensate for the daily flow pattern. On a typical day, no operator intervention is required. The operator was able to lower the chlorine setpoint, no longer needing to run at a higher setpoint for
'margin' against fast increases in flow."
The following Application Notes and Technical Papers are available:
See other applications.
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