Optimizing Pump Systems for Energy Efficiency Gunnar Hovstadius,Ph.D., Director of Technology Don Casada, SR. Development Associate, Oak Ridge NL Goulds Pumps Flygt A-C Custom Pump Bell & Gossett Jabsco Standard Vogel Lowara Barton McDonnell & Miller Richter Pure Flow ITT Fluid Technology

What Is A Pump System? A Pump System comprises of all piping, fittings and valves before and after a pump as well as the motor and motor driver. There can be multiple pumps, motors and drives, and they can be arranged to operate in parallel or in series. Pump Systems can have static head (pressure), or be circulating systems (friction only systems)

3 First, Let's Get A Big Picture Perspective Of Energy Flow in Pumping Systems Electric utility feeder Transformer Motor breaker/ starter Motor Adjustable speed drive (electrical) CouplingPump Fluid system Ultimate goal At each interface, there are inefficiencies. The goal should be to maximize the overall cost effectiveness of the pumping, or how much flow is delivered per unit of input energy.

Specific Energy E s = Motor efficiency = Pump efficiency m  E s = f HS  g m  H S = Fluid density = Gravitational constant = Static head = Hydraulic System factor  f HS H S g = P el x Time Pumped Volume p  p 

5 Observations On Some Of The Power Train Components Utility system - line losses (we can’t do much about that) Transformer - Very efficient (typically high 90’s %) Breaker/starter - negligible losses Adjustable speed drive - To be discussed Motor - To be discussed Coupling - Losses better be minor! Pump - To be discussed System - To be discussed Ultimate goal - To be discussed

6 Understand The Ultimate Goal Electric utility feeder Transformer Motor breaker/ starter Motor Adjustable speed drive (electrical) CouplingPump Fluid system Ultimate goal Maximize the overall effectiveness.

7 It Is Essential To Understand The Ultimate Goal Of The Fluid System To Optimize It Understand why the system exists Have clearly defined criteria for what is really needed Understand what's negotiable and what's not

Requirements For Designing A System Duration Curve (Flow) System Curve (Pressure vs. Flow) Pump & Component selection

Time [hours] Inflow [GPM] Annualized Flow Duration Curve

10 Understand The Fluid System Electric utility feeder Transformer Motor breaker/ starter Motor Adjustable speed drive (electrical) CouplingPump Fluid system Ultimate goal Maximize the overall effectiveness.

11 System Curves Are Made Up Of Two Fundamental Components - The Static Head And The Frictional Head Head, ft Flow rate, gpm Static/ Fixed Friction Total

Hydraulic System Factor The Hydraulic System factor is defined as “The ratio of a hydraulic system’s static head to total head”. Head Flow Total head Loss Head Static Head SYSTEM CURVE HS f f f HS H S H S + H F =

13 What Are Some Sources Of Friction In Pumping Systems? Pipe walls Valves Elbows Tees Reducers/expanders Expansion joints Tank inlets/outlets (In other words, almost everything that the pumped fluid passes through, as well as the fluid itself)

Operational Costs Are Influenced By The Selection Of Components And Their Size

Annual Frictional Cost Per 100 ft Of Pipe Assumptions: 80% combined pump and motor efficiency, electricity cost = 10 ¢/kWh

Frictional Losses Can Be Translated Into Operating Costs 12-inch line, 100 ft length, 10¢/kWh, full open valves, 80% combined pump & motor efficiency Assumptions:

17 Understanding The Pump Electric utility feeder Transformer Motor breaker/ starter Motor Adjustable speed drive (electrical) Coupling Pump Fluid system Ultimate goal Maximize the overall effectiveness

18 Nameplate Data Applies To One Particular Operating Point Head, ft Flow rate, gpm Rated: 3190 gpm, 97 ft Head-capacity curve

How Do We Know Where We'll Be Operating On The Pump Curve? Pump and system curve intersection (operating point) System head curve Pump head curve Nameplate

Efficiency And Brake Horsepower Are Commonly Plotted vs. Pump Flow Operating point BEP

Using A Larger Pipe Changes The Frictional Part Of The System Curve System head, 12" pipe System head, 16" pipe

Specific Energy in Three Different Single Pump Systems Throttling VSD Regulation Speed / Flow No static head 85% static head 50% static head Speed / Flow On-Off Regulation

24 Now Let's Look At The Electrical End Of The Shaft Electric utility feeder Transformer Motor breaker/ starter Motor Adjustable speed drive (electrical) CouplingPump Fluid system Maximize the overall effectiveness Ultimate goal

Motor Efficiency Curves Are Dependent Upon Size And Type

26 Understanding Drive Performance Electric utility feeder Transformer Motor breaker/ starter Motor Adjustable speed drive (electrical) CouplingPump Fluid system Ultimate goal Maximize the overall effectiveness

The Efficiency Of Inverters Is Affected By Operating Speed efficiency(%) speed (% of rated) Typical inverter efficiencies as a function of motor speed

Evaluate System Design Is the system effectiveness acceptable? If the system has static head, Compare with frictionless performance!

Re-Evaluate System Choices Relative To Needs Number of pumps Pump sizes VFD operation? Pipe diameters Component selection

When the System is Commissioned the Theoretical Calculations Should be Compared to Actual Operational Data to Ensure that it is Operating as Intended

Summary Most avoidable losses are in the pump and fluid system, not in the electrical front end However, the electrical front end can help reduce the fluid system losses Be careful with local optimization Determine the specific energy and compare with the ideal

THANK YOU Gunnar Hovstadius