Fifteenth Annual Vail Operator Training Seminar

1. Fifteenth AnnualVail Operator Training Seminar • Understanding Centrifugal Blower Operation in Wastewater Aeration and Dissolved Oxygen Control • Presented by: • Nicholas Radley • Project Engineer • N.E. Controls, LLC

2. Aeration Control Overview • N.E. Controls History • Blower Basics • Aeration Control Systems • Aeration Control Equipment

3. N.E. Controls, LLC • Lamson / Hoffman Empire in Syracuse, NY • Gardner-Denver buyout • Peachtree City, Georgia or bust • Three partners formed N.E. Controls in 1997 • Almost 60 combined years of experience in the blower business. • Now our business of 10 employees build various controls for use in Water / Wastewater treatment and other industries.

4. Centrifugal Blower Basics • Flow based machine not pressure based • More similar to a fan than a compressor • Excels at moving large volumes or air but not overcoming large pressure gradients

5. How a Blower Works • First-stage impeller draws air through inlet • First-stage air is forced outward, away from shaft and casting design directs air into second-stage impeller • Flow pattern continues through machine until air is exhausted though outlet.

6. Blower Customization • Output pressure increases as more stages are added • Blower pressure and flow characteristics can be tuned with different combinations of stages, impeller profiles and power ratings

7. Efficient Operation of Blowers • Throttling: • VFD (Speeding) • Discharge Valve • Blowoff Valve • Inlet Valve • Inlet throttling is the most cost effective way to throttle a centrifugal blower

8. The Blower Performance Curve • Top curve is Amps vs. Flow • Bottom curve is Pressure vs. Flow • Blower always runs at system resistance pressure • Throttling shifts curve to lower values

9. Centrifugal Blowers for AerationControl System Options • Manual Control • Header Pressure Control • Air Flow Control • Dissolved Oxygen Control

10. Manual Control • “Looser” Control • Update time in hours to days range • Typically uses excessive energy • Power savings vs. automated system • Man-hour costs

11. Header Pressure Control • Common control scheme used for positive displacement blower systems • Centrifugals always run at system resistance pressure • Does not transfer very successfully to centrifugal blower systems

12. Air Flow Control • For effective control need flowmeter on every drop • Works well with centrifugal systems • Expensive • Ultimately need DO measurements for permit info anyway

13. DO Control • Direct control of desired process variable • Modern DO sensors are more user friendly • Update times are slower than flow or pressure systems

14. Aeration Automation Concerns • Blower Sizing Requirements • Sensors Required • Automated Valves

15. Blower Sizing • Blower Frame Size / Configuration • Blower Turndown • Blower Overlap • Can different sized blowers run together? • Pressure requirements

16. Sensors • Dependent on control scheme • Process Sensors • Pressure, Flow, DO • Blower Protection and Monitoring • Vibration, Flow, Amps, Temperature, Hours, Pressure

17. Automated Valves • Are there existing valves or actuators? • Open/Close or 4-20 mA actuator • Valves sized correctly? • Provides more precise and frequent positioning than manual control

18. Questions / Comments