Pressure Management - Not Your Father s Approach

Transcription

1 Pressure Management - Not Your Father s Approach IWA Water Loss Control Conference Cape Town, South Africa May 8, 2018 Carl Yates, General Manager

2 1 Pressure Management Pressure management is one of the four key strategies of the IWA Water Loss Control Methodology. Reducing pressure will reduce breaks. There is a direct relationship between pressure and the amount of leakage. Reduced pressure reduces flow rates from active and background leakage.

3 2 Water Mains-Under Pressure

4 3 Pressure Management Typical Night Time Pressure Creep Pressure increases as flow decreases

5 4 Evolution of Pressure Management Pressure Reducing Valves (fixed outlet control) Pressure control through flow modulation with single feed to a DMA (allows downstream pressure to trend with flow, with limits) Pressure control through flow modulation with Dual Feeds to a DMA Pressure Management UARL Potentially Recoverable Annual Volume of Real Losses

6 Slide 5 Dartmouth Central

7 Dartmouth Central DMA %U Leaman PRV %U Micmac PRV AZP Critical Node Albro PRV %U Elmwood PRV %U MacDonald Booster Mains Length 59 KM Service Connections 3158 Hydrants 243 Wyse Rd PRV 6 (X %U %U Ave Zone Pressure Critical Node Press 56M 32M

8 7 Advanced Pressure Management The evolution of pressure management at Halifax Water has resulted in several iterations of the solution Pressure Flow

9 8 Single Supply Control Take One First solution implemented flow modulated (FM) pressure control using an air operated pilot bias chamber controlled by a proprietary controller.

10 9 Single Supply Control Take One This system accomplished FM pressure control, however, friction between the bias chamber s metal rod and housing caused the system to frequently respond erratically. In addition, any air leak in the system lines would cause a loss of control if the small controller pump could not keep up. As a result, a second solution was implemented and tested.

11 10 Single Supply Control Take Two Second solution implemented flow modulated pressure control using a hydraulically operated pilot bias chamber controlled by a proprietary controller.

12 Minimum Night Flows [WRF Project 2928] No Control - Fixed Outlet - Flow Modulated 11 Graph reflects single feed from Leaman Supply Chamber

13 Water Savings (M³/Year) Annual Water Savings Flow Modulated vs. Fixed Outlet FLOW MODULATED FIXED OUTLET 250, ,000 34,311 Total Water Savings 229,661 m3/yr. 150, ,000 50, ,350 Total Marginal Costs Savings $16,305 / Year 0 Total Construction Costs = $200,

14 Dartmouth Central DMA Before and After Leak History Avg. Annual: 2002/ /05 (3 years) Main Leaks = 23 Pub. Service Leaks = 4 Priv. Service Leaks = /2006 Main Leaks = 12 Pub. Service Leaks = 2 Priv. Service Leaks = 3 Pressure Management UARL Potentially Recoverable Annual Volume of Real Losses 13

15 14 Single Supply Control Take Two During this implementation, hydraulic issues associated with a dual supplied DMA also became apparent. An increase in output from one supply chamber caused a reduction in flow at the second supply chamber, eventually shutting the second feed in.

16 15 Dual Supply Control Take Three To ensure two feeds delivered water to the DMA, a control algorithm that combined both PRV flows into a total system flow was incorporated. The total system flow was communicated via radio to both PRV controllers in real time (few seconds).

17 Solving The Dual Supply Challenge Take Three Flow Flow 16 Control Algorithm Micmac PRV Leaman RTU PRV Controller Leaman Flow Total DMA Flow PRV Pilot Control

18 17 Each Supply Chamber Contributes 44 % Total Flow 56 % Total Flow June 12, :00 PM June 15, :00 PM

19 18 Celebrate Success CSCE Award In 2014, Halifax Water won the Canadian Society of Civil Engineering Award [CSCE] for engineering innovation. Advanced Pressure Management Utilizing Automated PRV Control in a Dual Supply DMA. No time to sit on our laurels; still more work to do.

20 19 Dual Supply Control Take Four Although this system worked well, a few minor issues still existed with the proprietary hardware. For example, if the controller hardware failed resulting in loss of bias chamber control, the PRV s pilot valve would default to a low pressure set point. When proprietary controller hardware components did fail, they were expensive to replace. In addition, any remote set point programming required the purchase of additional proprietary hardware which was not easily incorporated into the existing SCADA system. As a result of these and other minor issues (battery life), a fourth in-house design solution was implemented and tested.

21 Dual Supply Control Take Four In-House Design Solution 20 Fourth solution implemented flow modulated pressure control using electric solenoids controlled by a PLC. PLC reduces system pressure as demand decreases

22 21 Dual Supply Control Take Four In-House Design Solution Flow Flow PLC Algorithm using Total DMA Flow Micmac PRV Leaman RTU Solenoid control Leaman Flow

23 22 In-House Design Solution Take Four The system works reliably! Comparison of pressure/flow data from 2006 through to 2018 shows we are achieving similar desired results as the original successful testing.

24 23 Long Term Results.How Are We Doing? Avg. night time pressure ~ 300 kpa 2006 Avg. night time flow ~ 70 M3/h

25 24 Long Term Results.How Are We Doing? Avg. night time pressure ~ 300 kpa 2012 Avg. night time flow ~ 72 M3/h

26 25 Long Term Results.How Are We Doing? Avg. night time pressure ~ 300 kpa 2018 Avg. night time flow ~ 68 M3/h

27 26 In-House Design Solution Benefits System contains no proprietary hardware (only off-theshelf components). Hardware from multiple vendors (PLC type, solenoid type, for example) can be used, eliminating proprietary concerns, or end-of-life components. Control algorithms can be easily modified by HW staff to accommodate desired system changes. Pressure management & advanced pressure management modes and set points can be controlled or disabled remotely via Halifax Water SCADA system.

28 Pressure Reduction Via In-Line Turbine The Fun Continues Project Economics COMFIT Project ~ $0.14/kWh Capacity ~ 33 kw / 225,000 kwh/yr Revenue ~ $32,000/yr Project Cost ~ $468,000 Funds from Water Research Foundation and NS Environment [$200,000] IRR ~ 11.4% [based on $268,000] SPB ~ 8.6 Years Slide 27

29 28 Do not follow where the path may lead. Go instead where there is no path and blaze a trail