ACADs (08-006) Covered

KeywordsAir compressors, aftercooler, afterfilter, moisture separator airflow.

Description

Supporting Material

Service and Instrument Air

5.2.2.9

Service&

InstrumentAir

2

Objectives:

5

1. Describe the difference between service air and instrument air; state the purpose of each.

2. List the main components of the service / instrument air systems and describe their functions.

3. Describe the flowpath of air through the service / instrument air system using a one-line diagram.

Service & Instrument Air

Purpose: Provide a source of reliable compressed

air to air operated plant equipment.

Uses: Service air is generally of lesser quality than instrument air. Service air is piped to outlets for temporary equipment and instrument air is piped to permanently-installed, pneumatically-operated equipment.

6

Rotary Air Compressor: Turbine Building Level A

7

a. 2 per unit

b. Normal operating pressure 117 psig

c. Capacity - 750 SCFM

d. 200 HP motor

e. Seal fluid seals the intermesh of two screw-type blades

f. Air coolant receiver - cools seal fluid, removes fluid, and returns it back to screws

Reciprocating Air Compressor

8

a. 1 per unit, 1 shared

b. Normal operating pressure 125 psig

c. Capacity 885 SCFM

d. 200 hp motor

e. Piston and cylinder type

f. Uses no seal fluid therefore no air coolant receiver needed

Aftercooler

9

•Compressed air gets hot so must be cooled•7 (1 for each compressor)•Air/water Heat Exchanger•Air on shell side•Cooling water on tube side•Cooling water from Turbine Plant Closed Cooling Water (TPCCW)

Moisture Separator

10

a. 7 (1 per compressor)b. Mechanical type -- air flow hits baffles inside and drops water outc. Removes condensed moisture from cooled air

1st & 2nd Stage Contaminant Filters

11

a. Used with rotary compressor

b. Backup seal oil removal

c. 1st stage = .3 micron2nd stage = .01 micron

Air Receiver

12

•7 (1 per compressor)•150 ft. 3•Rated pressure 150 psig•Dampening effect

Prefilter

13

•3 total

•Coalescing type (oil vapor/particulate)

•Removes oil and contaminants before dryer

Air Dryer

14

Each dryer = two tanks w/ alumina desiccant

Service Dryer:• 1 dryer• 1200 SCFM

capacity

Instrument Dryer:• 2 parallel dryers • 740 SCFM

capacity

Afterfilter

15

• 3 (1 after each dryer)

• Filter desiccant fines

• Remove .07 micron

Service& InstrumentAir

Intake Filter

Air Compressor(Rotary)

Air CoolantReceiver

After Cooler

MoistureSeparator

ContaminantFilter

FirstStage

SecondStage

AirReceiver

LCV

LCV

Drain

Drain

Intake Filter

Air Compressor(Rotary)

Air CoolantReceiver

After Cooler

MoistureSeparator

ContaminantFilter

FirstStage

SecondStage

AirReceiver

LCV

LCV

Drain

Drain

Intake Filter

LCV

Drain

MoistureSeparator

After Cooler

AirReceiver

LCV

Drain

Air Compressor(Reciprocating)

Intake Filter

LCV

Drain

MoistureSeparator

After Cooler

AirReceiver

LCV

Drain

Air Compressor(Reciprocating)

ToUnit 2

To AirDryer

FLOW PATH:1. Compressors2. Aftercooler3. Moisture separator4. Contaminant filter5. Air receiver

3

1

1

53

2

2

2

2

1

1 5

3

3 5

5

4

4

16

Service & Instrument AirF

F

F

F

F

F

To ServiceAir Header

To OtherUnit

To InstrumentAir Header

CompressedAir Inlet

ServiceAir Dryer

InstrumentAir Dryer "A"

InstrumentAir Dryer "B"

Exhaust

Exhaust

ExhaustExhaust Exhaust

Exhaust

FLOW PATH:6. Pre-filter7. Dryer8. After Filter9. To respective headers

9

6

6

6

7

7

7

9

8

88

17

Objectives Review:

18

1. Describe the difference between service air and instrument air; state the purpose of each.

2. List the main components of the service / instrument air systems and describe their functions.

3. Describe the flowpath of air through the service / instrument air system using a one-line diagram.