Approach to Aeration System Upgrade

Transcription

1 Approach to Aeration System Upgrade Northwestern Ontario Water and Wastewater Conference Thunder Bay, Ontario October 28 & 29, 2010 Earning your trust through reliable and efficient water management services.

2 2 Content Objectives Assessment Air blowers Diffusers Data logging Results and discussion Conclusions Recommendations

3 3 Objectives Optimize Treatment Process Aeration system Chemical system(s) Energy usage Operation

4 4 Air Blower Assessment Positive Displacement (PD) vs. Turbo Blowers Superior performance of turbo blowers Turbo Blowers OCWA invited 6 companies from 3 continents to compete

5 5 Neuros Turbo Blower Permanent magnet synchronous motor Bump foil air bearing Forged single stage impeller Allen Bradley control panel(s) CSA certification Life long extended warranty Small footprint Low noise Zero maintenance No vibration

6 6 Air Diffuser Assessment Course vs. Fine Bubble Diffusers ~45% higher oxygen transfer efficiency of fine bubble diffusers Fine Bubble Aeration Systems OCWA invited 5 companies from North America and Europe to compete

7 7 OTT Diffuser Fine bubble tubular membrane diffuser system High tech injection molded silicon membranes Stainless steel vertical drops and laterals High oxygen transfer efficiency (SOTE = 47%) OTT membranes installed at > 5,000 WWTPs

8 OTT System 8

9 9 Data Logging Objective Confirm efficiency numbers Demonstrate actual energy savings Recorded Parameters Power uptake Dissolved oxygen Air flow velocity

10 10 Data Logging Studies at WWTPs Orangeville 75 HP Turbo vs. 75 HP PD Kingston West 150 HP Turbo vs. 250 HP PD Black River-Matheson 30 HP Turbo vs. 75 HP PD Carleton Place 50 HP Turbo vs. 20 HP PD

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14 Power (kw) Discharge Airflow (10 3 SCFM) and Dissolved Oxygen Conc. (mg/l) 14 Orangeville Wastewater Treatment Plant 75 HP Turbo Blower % 1.4 mg/l 100% 4.7 mg/l 88% 2.4 mg/l 100% 5.7 mg/l 0 0 March 18, 2010 Time April 1, 2010 Power Discharge Airflow Dissolved Oxygen

15 Power (kw) Discharge Airflow (10 3 SCFM) and Dissolved Oxygen Conc. (mg/l) 15 Orangeville Wastewater Treatment Plant 75 HP Positive Displacement (PD) Blower PD Blower energized 8 PD Blower energized mg/l 0.7 mg/l Turbo Blower energized 0.6 mg/l April 1, 2010 Time April 16, 2010 Power Discharge Airflow Dissolved Oxygen

16 Discharge Airflow / Power (SCFM/kW) 16 Orangeville Wastewater Treatment Plant Normalized Power Draws (March 18 April 16, 2010) DO =2.2 mg/l n = DO = 0.65 mg/l n = 719 DO = 4.3 mg/l n = Discharge Airflow (SCFM) 88% to 89% speed 100% speed PD Blower

17 Power (kw) 17 Orangeville Wastewater Treatment Plant Average Power Demand vs. Average DO PD Air Blower n = / 39.2 = Turbo Blower n = / 0.65 = Dissolved Oxygen (mg/l)

18 Power (kw) Discharge Airflow (10 3 SCFM) and Dissolved Oxygen Conc. (mg/l) 18 Kingston West Wastewater Treatment Plant 250 HP Positive Displacement Blower Average DO = 4.7 mg/l April 26, 2010 Time May 10, 2010 Power Discharge Airflow Dissolved Oxygen

19 Power (kw) Discharge Airflow (10 3 SCFM) and Dissolved Oxygen Conc. (mg/l) 19 Kingston West Wastewater Treatment Plant 150 HP Turbo Blower % 99% 100% 99% 97% 98% 96% Average DO = 4.2 mg/l May 10, 2010 Time June 4, 2010 Power Discharge Airflow Dissolved Oxygen

20 Discharge Airflow / Power (SCFM/kW) 20 Kingston West Wastewater Treatment Plant Normalized Power Draws (April 26 to June 4, 2010) HP Turbo Blower DO = 4.2 mg/l n = 2, Discharge Airflow (10 3 SCFM) PD Blower 250 HP PD Blower DO = 4.7 mg/l n = 1,295 Turbo Blower

21 Power (kw) 21 Kingston West Wastewater Treatment Plant Average Power Demand vs. Average DO / 105 = HP Turbo Blower n = 2, HP PD Air Blower n = 1, / 4.2 = Dissolved Oxygen (mg/l)

22 22 Conclusions At same aeration rate, turbo blowers resulted in significantly higher DO concentration. High correlation (R 2 =0.975) between turbo blower speed and energy draw. In the absence of feedback controls, the operation of both the turbo and PD blowers resulted in a significant DO concentration variation (0.4 mg/l to 8.5 mg/l) in the aeration tanks.

23 23 Conclusions (cont d) With the permanent magnetic motor there is no power surge at the startup of the turbo blower (i.e. the startup power is the same as the operating power, which has economic implications). A fully upgraded aeration system could result in up to 65% power savings and a payback period of as short as 2 years. The payback period of blower replacement alone is typically 3 to 6 years.

24 24 Recommendations To replace conventional air blowers with high efficiency turbo blowers To replace course bubble diffusers and/or their failing fine bubble counterparts with fine bubble tubular membrane diffuser To control blower speed by DO concentration To undertake power logging studies

25 25 Acknowledgements Kingston Staff Thomas Flynn (OCWA) Orangeville Colleagues Black River Matheson Colleagues Carleton Place Colleagues