Specifying Irrigation Pump Stations

Transcription

1 Specifying Irrigation Pump Stations Today: How to Size and Specify Suction Lift Pumps Tony Adamson Rain Bird Pump Sales & Marketing Manager

2 Pump Station Basics Pumps create pressure not flow XX gpm in XX gpm out at an increased pressure of psi The available flow is a function of the water source not a function of the size of the pump Pumps create specific pressure at rated flow Constant pressure / flow curve As flow increases pressure decreases As flow decreases pressure increases Variable Frequency Drives (VFD s) are used when flow demand varies at constant pressure Like an accelerator on a car varies motor / pump speed Not needed when flow is constant Can also vary pressure for zone control

3 How to Size and Specify Pumps for Suction Lift Applications

4 Suction Lift Application Atmospheric pressure 14.2 PSIA (1,000 elev.) Suction piping friction loss = 3 8 Atmospheric pressure = 32.8 (14.2 X 2.31) Elevation of source = -8 (below pump) Suction plumbing friction loss = 3 NPSH A = = 21.8

5 What is the Water Source? Well Lake or Pond River or Ditch Public Source Above Ground Tank Below Ground Tank Potable Water Well Water Reclaim Water Agriculture Water Snowmelt or Storm runoff Chiller or A/C Water Rainwater

6 What needs to be determined to specify a pump? Required Flow Rate Inlet and Discharge Pressure Water Application Requirements (e.g., water window) Pump Station Location any restrictions such as size, existing building, view of the public, etc. Elevation impacts how the pumps are rated Inlet/Outlet piping size requirements Available power in volts/phase/hertz

7 Pumps for the Application Split Case Centrifugal Typically up to 2000GPM Typically up to 130PSI Vertical Multi-Stage Horizontal End Suction Vertical Multi-stage Up to 500GPM per pump Wide range of pressure

8 Vertical Turbine Pumps for the Application Vertical Turbine Typically up to 1000GPM per pump Wide range of pressure Motor on top Submersible Turbine Typically up to 600GPM per pump Wide range of pressure Motor on bottom Submersible Turbine Pump Motor Location Pump Motor Location

9 Key Numbers and Units You get 120PSI for every 10HP 60HP pump delivers 120PSI 75HP pump delivers 120PSI If pressure, flow 100PSI = 231FT The discharge of a pump is usually stated in Feet The discharge of a pump station is usually stated in PSI Friction Loss (Schedule 40 Steel Pipe) 1000GPM in a 10 pipe suffers 5FT head loss per 1000FT of pipe

10 Electrical Power Most common types of power in U.S. 460 V, 60Hz, 3Φ Can power pumps up 500HP 230 V, 60Hz, 3Φ Can power pumps up to 100HP 230 V, 60Hz, 1Φ The largest motor available in 1Φ 230V is 10HP Rest of the World Power: Canada: 575 V, 60Hz, 3Φ Asia & Middle East: 380V, 50Hz, 3Φ

11 Hydraulic Design - Pump Curves

12 The Pump Curve Bowl Power BEP (Best Efficiency Point) Bowl Efficiency NPSHr

13 The Pump Curve Bowl Power The power input required to generate a given flow and pressure. Bowl Efficiency The ratio of hydraulic power output from the bowl to the power input to the bowl e.g. A bowl with required a 75HP motor to generate a 50HP hydraulic output would have a Bowl Efficiency of 50/75 = 67% BEP (Best Efficiency Point) Point of highest bowl efficiency. You want your operating point to be as close to BEP as possible. NPSHr Net Positive Suction Head Required Pressure required on the intake side of the pump to ensure proper operation.

14 The Pump Curve Bowl Power The power input required to generate a given flow and pressure. Bowl Efficiency The ratio of hydraulic power output from the bowl to the power input to the bowl e.g. A bowl that requires a 75HP motor to generate a 50HP hydraulic output has a Bowl Efficiency of 50/75 = 67% BEP (Best Efficiency Point) Point of highest bowl efficiency. You want your operating point to be as close to BEP as possible. NPSHr Net Positive Suction Head Required Pressure required on the intake side of the pump to ensure proper operation.

15 The Pump Curve Bowl Power The power input required to generate a given flow and pressure. Bowl Efficiency The ratio of hydraulic power output from the bowl to the power input to the bowl e.g. A bowl with required a 75HP motor to generate a 50HP hydraulic output would have a Bowl Efficiency of 50/75 = 67% BEP (Best Efficiency Point) Point of highest bowl efficiency. You want your operating point to be as close to BEP as possible. NPSHr Net Positive Suction Head Required Pressure required on the intake side of the pump to ensure proper operation.

16 The Pump Curve Bowl Power The power input required to generate a given flow and pressure. Bowl Efficiency The ratio of hydraulic power output from the bowl to the power input to the bowl e.g. A bowl with required a 75HP motor to generate a 50HP hydraulic output would have a Bowl Efficiency of 50/75 = 67% BEP (Best Efficiency Point) Point of highest bowl efficiency. You want your operating point to be as close to BEP as possible. NPSHr Net Positive Suction Head Required Pressure required on the intake side of the pump to ensure proper operation. Remember: Pumps don t suck!

17 Pump Selection Based on pressure and flow

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19 Electrical Calculations

20 Estimating Station FLA **For 208V applications, increase the FLA by 10% To calculate the FLA of a pump motor operating on a VFD, multiple the nominal FLA by 1.24 To estimate FLA, multiple the largest load by 1.25 and then add this to remaining component FLAs. Example: a 460V 2 x 50HP pump station with a 5HP PM pump would have an FLA of Amps Amps = 1.24x1.25x65A + 65A + 7.6A

21 Other Electrical Panel Components Surge Protection. Helps protect the pump station against transients associated with power disturbances. Step-down Transformer. Provides 120V single phase control power. Through-Door Mail Electrical Disconnect. Shuts off power to the electrical panel if the panel door is opened. Optional 7.5KVA Step Down Transformer. Provides additional 120V power.

22 Specifying a Suction Lift Station A sports complex cannot obtain the permits to build a wet-well for a proposed vertical turbine station or a vault for a flooded suction station. The site s only option is to purchase and install a Suction Lift Pump Station. The sports complex requires 1000GPM at 120PSI. The vertical distance between the surface of the irrigation pond and the centerline of the proposed pump station intake pipe is 8FT (Suction lift is best used for under 15FT). The altitude at the site is 700FT. Available power is 460V, 3Φ

23 Specifying a Suction Lift Station Suction Lift Stations require that a check valve be installed at the inlet of the suction piping to ensure water in the suction pipe does not flow back out after pumps stop running. This type of check valve is referred to as a foot valve.

24 Specifying a Suction Lift Station 120 PSIG NPSHA 500GPM 1000GPM 8 FT 500GPM We need to solve for NPSHA first Net Positive Suction Head Available.

25 Calculating NPSHA H = The vertical distance between the surface of the irrigation pond and the center-line of the pump station intake pipe. L = Friction loss in the suction pipe. (Assume 5FT for this problem) A = Site Altitude (700FT in this problem. Atmospheric Pressure H = 8FT L = 5FT NPSHA = [2.31 x (14.7 ( x A))] H L = [2.31 x ( )] 8 5 = [2.31 x 14.35] 8 5 = 20.15FT

26 Specifying a Suction Lift Station NPSHA = 20.15FT 500GPM 120 PSIG 1000GPM 8 FT Next: 1) Calculate the required pump differential pressure. 500GPM 2) Verify NPSHA > NPSHR for a given pump selection.

27 Specifying a Suction Lift Station Required Differential Pressure = 120PSIG 20.14FT 120PSIG PSIG = 134.7PSI (2.31) = FT Required Differential Pressure = FT (Discharge) 20.14FT(Inlet) = 292FT Add 10PSI to account for station losses 10PSI = 23.1FT Total = 292FT FT = 315FT

28 Specifying a Suction Lift Station NPSHA = 20.15FT 500GPM at 315FT 120 PSIG 1000GPM 8 FT 500GPM at 315FT We built 10PSI of station loss into our calculation.

29 Horizontal End Suction 60 HP 75% Efficient Verify NPSHA > NPSHR NPSHA = 20.14FT NPSHR = 11FT

30 Vertical Multi-Stage 50 HP 74.1% Efficient 50 HP pump does not quite reach the required lift. It would require 3-40 HP to meet the lift and stay below the NPSH

31 Vertical Multi-Stage 50 HP 74.1% Efficient At pump run out, the NPSH would exceed the 20 psi maximum

32 Specifying a Suction Lift Station Result: two 60HP horizontal end-suction pumps. Efficiency at the design point is 75%. Bowl power at the design point is 51.8HP Now calculate the estimated station FLA: Station FLA = 1.25 x Largest FLA + Remaining FLAs 1.25 x 1.24 x 77A + 77A + 7.6A = 204A (200A Service)

33 Suction Lift Problems Loss of Prime The pressure in the suction line is less than atmospheric pressure. A leaking foot valve or suction pipe can allow air to leak into the suction line. Air then replaces water at the inlet to the pump. This is referred to as a Loss of Prime. Pumps cannot pump air, so the pump just spins, performing zero hydraulic work. Air

34 Self-Cleaning Suction Lift Kits

35 Suction Lift Kit

36 Suction Lift Kit

37 Suction Lift Station

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39 IPP Aluminum Horizontal End Suction

40 Pump Station Options Control Systems Z-Pipe Stainless Steel Intake Box Screen Power Conditioner Pump Station Heater Lake Level Control Wye Strainer Power Zone Transformer Filter (Rain Bird, Amiad, Tekleen, Orival or Other) Cable or Radio Modems Fertigation Enclosures Magnetic Flow Meter (instead of the standard paddle wheel style) AC VFD Cooling Powder Coat, Stainless or HDPE

41 Display Options E1071 Full Color Touch Screen (Option) GT1020 Monochrome Touch Screen (Standard)

42 Optional Filtration

43 SiteControl/Smart Pump Pump Manager provides control of the pump via pressure and flow independently of the any remote system. Also, provides remote computer access to the pump. Smart Pump provides direct and real time communication between the pump station and the central control system Adjusts flow demand based on actual field conditions to maximize pump efficiency

44 Water Harvesting Rain, Storm or A/C water collection and storage Available from roofs, parking lots, or storm basins Storage tanks can be above or below ground Pumped into irrigation by either suction lift or submersible pumps Can supplement or be entire irrigation water ROI payback over a long period of time usually not the primary driver

45 Water Harvesting

46 Water Harvesting

47 Water Harvesting

48 Water Harvesting

49 Water Harvesting

50 Wet Well Suction or Submersible

51 Rain Bird Pump Stations Design Team Proposal packages with a standardized quotation are provided with 48 hours of completed requests. Drawings are available based on the most common configurations upon request. Factory Contacts: Request for Quotation Alejandro Carrillo (520) Robbi Tolksdorf (520) Fax # (520) pumps@rainbird.com Sales & Marketing Tony Adamson (520) Herb Hofmann (602) Product Manager Gordon Van Dyke (520) Pump Station Sales Team: (520)

52 The Intelligent Use of Water We believe it is our responsibility to develop products and technologies that use water efficiently. Our commitment also extends to education, training and services for our industry and our communities. The need to conserve water has never been greater. We want to do even more, and with your help, we can. IUOW Summits IUOW White Papers IUOW Film Competition IUOW Awards IUOW Scholarship Find more at