ACADs (08-006) Covered Keywords

1. Service and Instrument Air ACADs (08-006) Covered Keywords Air compressors, aftercooler, afterfilter, moisture separator airflow. Description Supporting Material

2. Service & Instrument Air

3. Objectives: Describe the difference between service air and instrument air; state the purpose of each. List the main components of the service / instrument air systems and describe their functions. Describe the flowpath of air through the service / instrument air system using a one-line diagram.

4. 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.

5. Rotary Air Compressor: Turbine Building Level A 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

6. Reciprocating Air Compressor 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

7. Aftercooler • 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)

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

9. 1st & 2nd Stage Contaminant Filters a. Used with rotary compressor b. Backup seal oil removal c. 1st stage = .3 micron 2nd stage = .01 micron

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

11. Prefilter • 3 total • Coalescing type (oil vapor/particulate) • Removes oil and contaminants before dryer

12. Air Dryer • Each dryer = two tanks w/ alumina desiccant • Service Dryer: • 1 dryer • 1200 SCFM capacity • Instrument Dryer: • 2 parallel dryers • 740 SCFM capacity

13. Afterfilter • 3 (1 after each dryer) • Filter desiccant fines • Remove .07 micron

14. Service & Instrument Air Intake Filter Contaminant Filter After Cooler Air Receiver Air Compressor (Rotary) First Second Stage Stage Moisture LCV Separator LCV Drain Air Coolant Receiver Drain Intake Filter Contaminant Filter After Cooler Air Receiver Air Compressor (Rotary) First Second Stage Stage Moisture LCV Separator LCV Drain Air Coolant Receiver Drain To Air Dryer Intake Filter After Cooler Air Receiver Moisture Separator Air Compressor LCV (Reciprocating) LCV Drain To Drain Unit 2 Intake Filter After Cooler Air Receiver Moisture Separator Air Compressor LCV (Reciprocating) LCV Drain Drain 5 1 2 3 4 5 1 FLOW PATH: Compressors Aftercooler Moisture separator Contaminant filter Air receiver 2 3 4 5 2 3 1 5 2 3 1

15. Service & Instrument Air To Instrument Air Header F F Instrument Instrument Air Dryer "A" Air Dryer "B" Exhaust Exhaust Exhaust Exhaust F F Compressed Air Inlet F Service Air Dryer To Service Air Header To Other Unit Exhaust Exhaust F 9 FLOW PATH: 6. Pre-filter 7. Dryer 8. After Filter 9. To respective headers 8 8 7 7 6 6 8 9 7 6

16. Objectives Review: Describe the difference between service air and instrument air; state the purpose of each. List the main components of the service / instrument air systems and describe their functions. Describe the flowpath of air through the service / instrument air system using a one-line diagram.