Pumping System Energy Audits & How They

Benefit Utilities

Presented by: Rick Alvarez

Background ◦ Cost of Pumping ◦ Pump and System Curves ◦ Best Efficiency, POR, AOR

Energy Audit Procedures ◦ Data forms ◦ Equipment

Collected Data and How to Interpret It ◦ Actual operating conditions vs. Duty Point

Real World Findings Summary

Energy used to operate pumps ◦ Dependent on flow rate, total pressure and

overall pump efficiency

Labor and parts to maintain pumps

The cost of operating pumps can be expressed as a cost/volume pumped or energy used/volume pumped (specific energy)

Individual numbers (such as power consumption, shaft power, flow, etc.) do not take into account the productive work done, and don’t provide a complete picture

Convenient units for specific energy are kWH/MG (kilowatt hours per million gallons pumped)

A pump curve shows the relationship between flow and pressure developed by a pump

Pre

ssure

Head (

FT

)

Flow (GPM)

Pump Performance Curve

Pre

ssure

Head (

FT

)

Flow (GPM)

Pump curves also give the pump efficiency and input power characteristics

Pow

er

(HP)

Eff

icie

ncy (

%)

Efficiency

Power

Pump Curve

•Static Head = vertical rise in the system

(relatively constant)

•Friction loss = dependent on flow rate,

pipe size and pipe material of the piping

system

Design Flow

Total Head

Friction Loss Head

Static Head

System Curve A system curve is a function of the static head (lift) and friction losses thru the system

Flow (GPM)

Head (FT)

A pumps duty point is the point at which the system curve crosses the pump curve

Duty point

Pump curve

System curve

Flow (GPM)

Pre

ssure

Head (

FT

)

It is always best for the duty point to be near the pump’s best efficiency point (BEP)

Pre

ssure

Head (

FT

)

Flow (GPM)

Efficiency

System curve

Pump curve

Duty point at BEP

•Preferred Operating Range

•70-120% BEP

•Allowable Operating Range

•50-125% BEP

Gather existing information ◦ Pump data (curves, model #s, etc.)

◦ Site data (see the form on the next slide)

Perform flow testing ◦ Inflow and drawdown for each pump

Collect input kW data on each pump

Verify all data on Energy Audit form

Usually less than 15 minutes per site

•Form contains all

pertinent info

•Pump Data

•Measurement data

•Calculations

•Must be complete in

order to be accurate!

Input kW meter

Level measuring device ◦ (or flowmeter)

What do you get? ◦ Complete report showing performance of each

pump

◦ Summary of possible inefficiencies in your pumping equipment

◦ Recommendations on repair or replacement of equipment

•Explanation of

tests that were

performed

•Background on

test procedures,

equipment

•Summary of

Design versus

Actual performance

•Offers comparison

of all stations

within a system

Curve is marked with BEP and also with current operating condition

This shows a pump operating at BEP, and therefore very efficiently

Curve is marked with BEP and also with current operating condition

This shows a pump that is running outside AOR, indicating a problem with the sytem or the pump.

Shows problem sites where pumps are operating outside AOR

Also shows recommended replacement pumps and potential savings

Cost of pumping= Energy + Maintenance ◦ Pumps that operate outside AOR cost more to

operate (inside POR is optimal)

Energy

Inefficient pumps use more energy (More $$)

Maintenance

More vibration

Premature seal wear/failure

Premature bearing wear/failure

Major repairs (More $$)

How does an energy audit benefit YOU? ◦ Alerts you to pending problems

Actual versus design

Operation outside AOR

◦ Can prevent catastrophic failures

Identified problems can be addressed before an emergency occurs

◦ Helps you focus your resources (staff and $$)

Limited hours in a day, limited $$

Use your resources where they’re needed most

◦ Provide ROI data to support equipment requests

•Electric Supplier Incentives

•All companies participate

•DTE, Consumers, AEP,

etc.

•Incentives are paid for

upgrading the efficiency of

your pumping equipment

•Typical incentives are

$0.08/kWh for first year

Duty Point

Average annual

flow (MG)

Efficiency

(kWh/MG)

Annual Energy

Use (kWh)

Cost/Year (assumes

$0.10/kWh)

Existing Pump 450 GPM @56' 39 661 25779 $2,578

Proposed Pump 450 GPM @56' 39 313 12207 $1,221

Savings 348 13572 $1,357

Incentive $1,086

• Replacing an inefficient pump saves money

EVERY year

• Assuming $8,000 replacement cost, the new

pump pays for itself in about 5 years!

Aging pumps and collection systems may not be performing as originally designed

Energy audits can provide valuable information about the operation of your pumping equipment

Typically done at little or no cost

Information can be used to reduce energy and maintenance costs, SAVING YOU $$$$