COMPRESSED AIR SYSTEM ENERGY SAVING PRACTICES

Transcription

1 COMPRESSED AIR SYSTEM ENERGY SAVING PRACTICES Ali Razban, PhD, PE, CEM, CP EnMS Dept. of Mechanical and Energy Engineering Indiana University Purdue University Indianapolis (IUPUI), Indianapolis, IN, August 1, 2018 Purdue School Engineering & Technology AGENDA Energy Consumption Modeling in Compressor Case Studies Potential Air Compressor Recommendations savings Energy Audit. 1

2 PURPOSE Analyze the overall energy consumption of an industrial compressed air system Analytical energy model for air compression of the overall system Identify the impact of various energy savings of individual subsystem on the overall system INTRODUCTION Energy Flow Diagram Pressure Loss Models Energy Efficiency [η] Process Effectiveness (ε) 2

3 INTRODUCTION ENERGY MODEL Components: compressor, intercooler, aftercooler, filter, refrigerant dryer and receiver tank Parameters: pressure [P], temperature [T], volumetric flow rate [Q], and air power [ ] AIR POWER Available energy rate of compressed air ln ln 3

4 ENERGY FLOW MODEL DIAGRAM PRESSURE LOSS MODELS Aftercooler Filter Refrigerant Air Dryer Pipe 4

5 PRESSURE LOSS MODELS - AFTERCOOLER Pressure Drop - dp (PSI) Exhaust Flow Rate - Q (m3/s) , dp = 8E-05Q R² = ,000 19, dp = Q R² = ,000 15, Pressure Drop Model for Aftercooler 13,000 11, , ,000 6,000 9,000 12,000 15,000 18,000 21,000 Exhaust Flow Rate - Q (CFM) Pressure Drop - dp (Pa) English SI PRESSURE LOSS MODELS: FILTER Element Grade Element Type Dry dp (psi) Dry dp (Pa) Wet dp (psi) Wet dp (Pa) Grade C Coarse , ,033 Grade F Fine , ,962 Grade S Superfine , ,995 5

6 PRESSURE LOSS MODELS: DRYER Pressure Drop Model for Refrigerant Air Dryer Pressure Drop - dp (PSI) Exhaust Flow Rate - Q (m3/s) dp = R² = dp = Q R² = ,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 Exhaust Flow Rate - Q (CFM) 38,000 35,000 32,000 29,000 26,000 23,000 20,000 17,000 14,000 Pressure Drop - dp (Pa) English SI PRESSURE LOSS MODELS: PIPE at 100 psi, 100 ft Pipe Type Schedule 40 Steel Type K Copper Type L Copper Schedule 10 Stainless Steel Flow Rate Flow Rate Pressure Pressure Drop Pressure Pressure Drop Pressure Pressure Drop Pressure Pressure Drop Pipe Size (cfm) (m3/min) Drop (psi) (Pa) Drop (psi) (Pa) Drop (psi) (Pa) Drop (psi) (Pa) 1/2" ,655-97, , , , ,655-97,561 3/4" , , , ,034-97,768 1" , , , , /4" , , ,756 NA NA 1 1/2" , , , ,361 2" 99-1, , , , , /2" 159-2, , , ,078 NA NA 3" 282-3, , , , ,153 4" 706-8, , , , ,882 6

7 ENERGY EFFICIENCY η " - total system energy consumption based on rated data and using theoretical energy equations " " - summation of ideal case plus energy losses through system (pressure loss, heat loss) SUB-SYSTEM BLOCK DIAGRAM AND ESTIMATED ENERGY CONSUMPTION 7

8 EFFECTIVENESS ε 1 " is proposed energy consumption of the energy saving recommendation following " ". EFFECTIVENESS Recommendations discussed: 1. Reduce Compressor Set Pressure 2. Using Outside Air for Air Compressor Intake 8

9 REDUCE COMPRESSOR SET PRESSURE Reducing Set Pressure Effectiveness (%) 10% 9% 8% 7% 6% 5% 4% 3% 2% 1% 0% dp (Pa) 0 20,000 40,000 60,000 80, , , dp (PSI) Fractional Savings Model Effectiveness USING OUTSIDE AIR FOR AIR COMPRESSOR INTAKE Outside Air Compressor Air Intake Effectiveness (%) Intake Air Temperature ( o R) % 4.5% 4.0% 3.5% 3.0% 2.5% 2.0% 1.5% 1.0% 0.5% 0.0% Intake Air Temperature ( o K) Work Reduction (%) Model Effectiveness (%) 9

10 CASE STUDIES 1. Die Casting 200 HP 2. Metal Parts 100 HP 3. Metal Parts 75 HP CASE STUDY

11 CASE STUDY - 1 Set Pressure: 105 PSI (724 kpa) = kw Efficiency = 76.2% Uncertainty: ~15% CASE STUDY - 2 Set Pressure = 115 PSI Demand Draw = 74.6 = 66.7 kw Efficiency = 89.4% Uncertainty = ~1% 11

12 CASE STUDY - 3 Set Pressure = 115 PSI Demand Draw = 53.2 kw = 49.5 kw Efficiency = 94.6% Uncertainty = ~4% CONCLUSION The model allows user to calculate and compare Ideal and Real system energy consumption. Air power data pinpoints potential problems and optimize overall system efficiency Model accuracy: 85% % 12

13 RECOMMENDATIONS I. Use Cold Air Intake II. Optimize Set Pressure III.Utilize More Efficient Compressed Air Users IV.Eliminate Air Leaks V. Compressed Air Waste Reduction VI.Heat Recovery VII.Utilize VFD On Compressed Air 13

14 The following data gathered from 103 companies which have been Energy Audited by Industrial Assessment Center IMPLEMENTATION DATA Time Recommended USE COLD AIR INTAKE OPTIMIZE SET PRESSURE 2 1 UTILIZE EFFICIENT CA USERS ELIMINATE AIR LEAKS Number of recommended times 2 2 CA WASTE REDUCTION Implemented times 13 5 HEAT UTILIZE VFD RECOVERY ON CA SYSTEM

15 ANNUAL COST SAVING Total Natural Gas Cost Saving ($) Total Electrical Demand Cost Saving($) Total Electrical Energy Cost Saving($) Total Cost Saving($) $0 $28,677 $76,983 $105,660 $0 $56,437 $136,038 $192,475 $0 $13,121 $953 $14,074 $0 $57,920 $0 $0 $4,698 $4,698 $38,430 $2,358 $19,935 $60,723 $0 $9,946 $63,462 $73,408 $422,670 $480,590 USE COLD AIR INTAKE OPTIMIZE SET PRESSURE UTILIZE ELIMINATE AIR EFFICIENT CA LEAKS USERS CA WASTE REDUCTION HEAT RECOVERY UTILIZE VFD ON CA SYSTEM ANNUAL ELECTRICAL ENERGY SAVING 8,000,000 kwh 7,574,386 kwh 7,000,000 kwh Electrical Energy Saving(kWh) 6,000,000 kwh 5,000,000 kwh 4,000,000 kwh 3,000,000 kwh 2,000,000 kwh 1,396,552 kwh 1,461,488 kwh 1,000,000 kwh 0 kwh USE COLD AIR INTAKE 300,377 kwh OPTIMIZE SET PRESSURE 28,068 kwh UTILIZE EFFICIENT CA USERS ELIMINATE AIR LEAKS 67,937 kwh 11,241 kwh CA WASTE REDUCTION HEAT RECOVERY UTILIZE VFD ON CA SYSTEM 15

16 ANNUAL ELECTRICAL ENERGY COST SAVING RANGE $39,950 $37,278 $34,950 Electrical Energy Cost Saving($) $29,950 $24,950 $19,950 $14,950 $9,950 $22,480 $21,068 $23,581 $4,950 -$50 $3,956 $4,867 $103 $98 $477 $476 $183 $742 -$45 USE COLD AIR INTAKE OPTIMIZE SET PRESSURE UTILIZE EFFICIENT CA USERS ELIMINATE AIR LEAKS CA WASTE REDUCTION HEAT RECOVERY $1,348 UTILIZE VFD ON CA SYSTEM Hightest Electrical Energy Cost Saving($) Lowest Electrical Energy Cost Saving($) ANNUAL ELECTRICAL DEMAND SAVING 9,000 kw 8,000 kw 8,145 kw 7,000 kw Electrical Demand Saving(kW) 6,000 kw 5,000 kw 4,000 kw 3,000 kw 2,000 kw 2,153 kw 3,572 kw 3,381 kw 1,000 kw 517 kw 941 kw 0 kw USE COLD AIR INTAKE OPTIMIZE SET PRESSURE UTILIZE EFFICIENT CA USERS ELIMINATE AIR LEAKS 0 kw CA WASTE REDUCTION HEAT RECOVERY UTILIZE VFD ON CA SYSTEM 16

17 ANNUAL ELECTRICAL DEMAND COST SAVING RANGE $24,300 $20,480 Electrical Demand Cost Saving($) $19,300 $14,300 $9,300 $4,300 $7,925 $17,070 $13,729 $19,070 $9,946 -$700 $20 $33 -$608 $48 $0 $0 USE COLD AIR INTAKE OPTIMIZE SET PRESSURE UTILIZE EFFICIENT CA USERS ELIMINATE AIR LEAKS Hightest Electrical Demand Cost Saving($) CA WASTE REDUCTION $722 $0 HEAT RECOVERY UTILIZE VFD ON CA SYSTEM TOTAL ANNUAL COST SAVING PROPORTION UTILIZE VFD ON CA SYSTEM 8% HEAT RECOVERY, 7% USE COLD AIR INTAKE 11% CA WASTE REDUCTION 0% OPTIMIZE SET PRESSURE 21% ELIMINATE AIR LEAKS 52% UTILIZE EFFICIENT CA USERS 1% 17

18 AVERAGE PAYBACK PERIOD Average Payback Period(month) USE COLD AIR INTAKE 0 OPTIMIZE SET PRESSURE UTILIZE EFFICIENT CA USERS 1 1 ELIMINATE AIR LEAKS CA WASTE REDUCTION HEAT RECOVERY UTILIZE VFD ON CA SYSTEM HIGHEST SAVING CASES RECOMMENDATION HIGHEST ENEGY SAVING (kwh) HIGHEST DEMAND SAVING (kw) HIGHEST NATURE GAS SAVING (MMBtu) HIGHEST ANNUAL COST SAVING ($) AIR COMPRESSOR HP USE COLD AIR INTAKE 306,309 kwh 449 kw 0 MMBtu $26, HP+200 HP OPTIMIZE SET PRESSURE UTILIZE EFFICIENT CA USERS 450,323 kwh 678 kw 0 MMBtu $31, HP+350 HP 15,068 kwh 546 kw 0 MMBtu $14, HP+350HP ELIMINATE AIR LEAKS 678,214 kwh 758 kw 0 MMBtu $37, HP+350HP+300HP CA WASTE REDUCTION UTILIZE VFD ON CA SYSTEM 56,767 kwh 0 kw 0 MMBtu $3, HP 7,860,248 kwh 941 kw 0 MMBtu $23, HP HEAT RECOVERY 11,288 kwh 472 kw 4,763 MMBtu $20, HP 18

19 ELIGIBILITY CRITERIA FOR ENERGY AUDIT Within Standard Industrial Codes (SIC) Within 150 miles of a host campus Gross annual sales below $100 million. Fewer than 500 employees at the plant site. Annual energy bills more than $100,000 and less than $2.5 million. No professional in-house staff to perform the assessment. Exceptions may be made through an approval process 19

20 CONTACT US Dr. Jie Chen, Director Dr. Ali Razban, PE, CEM, CP EnMS, Assistant Director Dr. David Goodman, CEA, Assistant Director Thank you! QUESTIONS? 20