why care about air? - aep ohio care about air? the 14 r’s ... •wasted energy is costing you...

2 | Compressed Air Optimization

Why Care About Air? The 14 R’s

9/25/2012

Presented by: Frank Moskowitz


• Compressed Air systems account for 10 percent of the

total industrial electrical consumption and are found in 70

percent of all manufacturing facilities in the United States

• The high cost of compressed air has led many to call it

‘the fourth utility’ along with electricity, gas and water.

• Compressed air’s efficiency can be as low as 10 percent.

• Wasted energy is costing you money.

Compressed Air Seminar & Expo


CAC Plant survey… The overall efficiency of a typical compressed air system can be as low as 10-15 percent

Annual energy costs for a 1 HP “air” motor versus a 1 HP “electric” motor, for 5 days per week, 2 shift operation @ $0.05/kWh

A 1 HP Air Motor uses about 30 CFM @ 90 psig or 7 – 8 HP of compressed air.

…$ 1,349 (compressed air)

…$ 168 (electric)

Did you know?


• Pneumatic equipment manufacturers spend a great deal

of money to obtain optimum efficiency of their individual

products, only to see much of the energy savings

squandered in a poorly designed and managed system.

• 14 specific means of reducing plant air system energy

costs have been identified.

The 14 R’s of Compressed Air Energy Management


• Leaks often account for more than

20% of the total amount of air

being compressed.

– Ultrasonic leak detectors are

available.

– An ongoing program involving

all departments is essential.

– A program in a U.S. auto plant

resulted in sustained savings

of over $2000/day.

#1 Reduce Leakage Losses


• The total system may be running at a higher pressure to

satisfy the needs of only one point of use.

– The single higher pressure point of use can be met

with a separate compressor or by a booster.

– The remainder of the system can operate at a lower

pressure, reducing leakage and usage rates and at

reduced energy consumption.

#2 Reduce pressure at points of use.



Major Features

Air Inlet Port

Air Drive Tube

Drive Piston

Upper Tappet Valve

Pilot Air Tube

Spool Valve

Lower Tappet Valve

Pilot Vent

Outlet Muffler

Inlet Check Valve

Outlet Check Valve

Drive Air Flow

High Pressure Air

Exhaust Flow


• Every additional 2 psi costs 1% in energy.

• Check the validity of compressor control settings.

• Check pressure drops through dryers, filters and piping

systems.

• Artificial Demand

#3 Reduce Pressure at Source


A leak consumes 42% more air at 120 psig than at

80 psig adding to the artificial demand on the system.

At 120PSIG

7.62 scfm FLOW

A 1/16 inch equivalent diameter leak

At 80PSIG

5.36 scfm FLOW


• Inadequately sized air receivers and distribution piping

can cause real problems.

• A primary air receiver shields the compressor from

system fluctuations.

• An air receiver before a dryer provides radiant cooling

and condensate fall-out.

• An air receiver after a dryer will be filled with dry air for

use when needed.

#4 Reduce System Pressure Fluctuations

15 | Compressed Air Optimization 15

Receiver located before the dryer:

• If the receiver is located before the compressed air dryer, the receiver may provide

radiant cooling and drop out some of the condensate and entrained oil, thus

benefiting the dryer.

• However, the receiver will be filled with saturated air, and if there is a sudden demand

that exceeds the capacity rating of the compressor and matching dryer, the dryer can

be overloaded, resulting in a higher pressure dew point.


Receiver located after the dryer:

• If the receiver is located after the compressed air dryer, some of the previous

mentioned advantages are lost.

• However, the receiver is filled with compressed air which has been cleaned and dried.

• A sudden demand in excess of the compressor and dryer capacity rating will be met

with dried air.


Receiver located before and after the dryer:

• A best practice is often to have two receivers at the supply side.

• One “wet” air receiver before the dryer to provide control storage and condensate

drop out.

• And a second “dry” air receiver to meet sudden demands.


Compressor 1

Compressor 3

Compressor 2

Air treatment components

(dryers, filters, etc)

Storage

Flow Controller

To

System

Pressure/Flow Control Location (Typical)

39


• With lubricant injected rotary compressors, adequate air

receiver/system volume is essential to allow the fully

unloaded state to be realized for energy savings.

#4 Reduce System Pressure Fluctuations (cont.)


Power Profile of Load/No-Load



• Base load as many compressors as possible.

#5 Reduce the number of compressors at reduced capacity.


80

110

105

100

95

90

85

Pre

ssure

(psi

g)

Production minimum requirement

Load pressure

Unload pressure

Single set point control pressure

Network Controls

Basic single set point control scheme


Network Controls


• Many applications can be served more efficiently by: low

pressure air from a fan, a blower; or by a vacuum pump,

rather than by compressed air. Examples:

– Cabinet cooling

– Liquid agitation or stirring.

– Vacuum generation.

#6 Remove Inappropriate Applications


Open blowing

Sparging (agitating, stirring,

mixing)

Aspirating

Atomizing

Padding

Dilute phase transport

Dense phase transport

Vacuum generation

Personnel cooling

Open hand-held blow guns or

lances

Cabinet cooling

Vacuum venturi

Diaphragm pumps

Timer drains/open drains

Air motors

Potentially Inappropriate Applications


Appropriate Applications


Rule #1, #2 and #6

Production 50%

Leaks 25-30%

Artificial Demand 10-15%

Poor Practices 5-10%


• Many systems have outgrown their original size

requirements.

• Distribution pipe diameters are too small . Velocities

should not exceed 20 ft/sec.

• Coolers, dryers and filters should be sized for maximum

flow conditions.

• Hoses and connectors are problematical.

#7 Reduce System Pressure Drop Losses


Mist Eliminator or Pipe Line Filters


Local Storage

Regulator set

to 70 psig in

this example

Restrictor valve

slows recovery of pressure

in the receiver

Check

Valve

70 psig

6 cf per pulse =

36 scfm refill flow

for 10 seconds

6 cf per pulse =

> 1000 scfm rate of flow

for .25 seconds

30 to 60 gallon

sized for the

application 60 psig


Local Storage


• Do not dry compressed air more than is required by the

application.

• Consider initial drying with a refrigerant type dryer then

drying further only to meet the requirement at a specific

point of use.

• The power requirement of a refrigerated dryer, including

the effect of pressure drop through the dryer, is 0.80

kW/100 cfm.

• The power requirement of a twin tower heatless desiccant

type dryer, including pressure drop through the dryer, is

2.0–3.0 kW/100 cfm

#8 Remove moisture with dryers of proper size and type.


EFFECTS OF WATER CONTAMINATION

• Washing away required lubricants

• Causing rust and scale to form within

pipelines

• Increased wear and maintenance of

pneumatic devices

• Sluggish and inconsistent operation of air

valves and cylinders

• Malfunction and high maintenance of

control instruments and air logic devices

• Product spoilage by spotting in paint and

other types of spraying


EFFECTS OF WATER CONTAMINATION

Rusting of parts that have been

sandblasted

Freezing in exposed lines during cold

weather

Further condensation and possible

freezing of moisture at the exhaust

whenever air devices are rapidly

exhausted


• Inspect drain traps regularly and repair as necessary.

• Do not allow open manual drain valves.

• Use drain traps which sense the presence of condensate

and drain it without loss of compressed air.

#9 Remove condensate without loss of compressed air.

VS

v

VS


#10 Reduce Downtime Through Preventive Maintenance


• Establish a baseline of system data before making any

changes.

• Establish a benchmark of energy consumption against

rate of production.

• Record any system changes made and resulting energy

savings.

• Record maintenance data and trends.

#11 Record system data and maintenance.


• Record operating pressures at strategic points in the

system. Changes can show problem areas.

• The impact of new production machines should be

reviewed.

• Low pressure at a point of use may be a system problem

rather than the need for another compressor.

#12 Review Air Usage Patterns Regularly


• Record operating pressures at strategic points in the

system. Changes can show problem areas.

• The impact of new production machines should be

reviewed.

• Low pressure at a point of use may be a system problem

rather than the need for another compressor.




Filter

300 HP

Centrifugal

200 HP

Dry Screw

Dryer

Receiver

Other uses

Other uses

Critical user

P

PPP P

P Indicates point for pressure measurements

F R L

P


• 85% of the power of a lubricant injected rotary

compressor is removed by the lubricant cooler.

• A radiator cooler can provide air for space heating of

buildings.

• Water cooled units can provide heating of water for plant

use.

#13 Recover Heat


Compressed Air’s Inefficiency: 85% of the power of the prime mover is converted into an unusable

form of energy (HEAT)

And to a lesser extent, into friction, misuse and noise

Recover Heat


Heat Recovery

Energy Recovery.exe


Heat Recovery


• An energy efficient compressed air system also can

improve product quality, reduce scrap rates and increase

profits.

• Reduced energy costs of a compressed air system go

right to the bottom line of the financial statement as

increased profits.

• An efficient compressed air system pays dividends!

#14 Reduce Energy Costs (Return On Investment)

why care about air? - aep ohio care about air? the 14 r’s ... •wasted energy is costing you...

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