Green economy with natural refrigerants

Transcription

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2 Green economy with natural refrigerants by

3 Reducing Ammonia Charge in Industrial Refrigeration Systems Using Direct Expansion by Bruce I. Nelson, P.E. President Colmac Coil Manufacturing, Inc.

4 Background Ammonia is recognized as an excellent refrigerant Environmentally benign (0 ODP, 0 GWP) Energy efficient Low cost Components widely available However, it is toxic I love ammonia, just don t put it too close to my people or products. Industrial ammonia refrigeration systems have traditionally used gravity flooded or pumped overfeed designs Good evaporator performance regardless of temperature Good evaporator performance over wide range in load Relatively insensitive to small amounts of water Simple to operate Unfortunately, these designs maximize the amount of ammonia near people and products (lots of ammonia in the evaporators)! Schaffhausen, 28 June 2013 Page 4

5 Background Direct expansion (DX) offers the following benefits: Reduction in amount of ammonia in the occupied spaces 30X to 50X charge reduction in evaporators Potential for reduced regulatory burden USA: Over lbs (4536 kg) Increased OSHA scrutiny (PSM requirements, NEP inspections) Increased EPA RMP requirements DHS CFATS compliance Europe: Over 3000 kg (6600 lbs) EN378 warehouse isolation requirements More stringent country-specific regulations 0.7 kg/kw now possible with DX vs 3 kg/kw for pumped bottom feed DX: 1, lbs, kg Pumped: lbs, kg Improved energy efficiency Faster pump out and shorter defrost cycle Energy Efficient Dry Suction Automatic removal of water Schaffhausen, 28 June 2013 Page 5

6 Background Q: So why haven t we been applying DX to industrial ammonia designs? A: Well It just doesn t work at low temperatures. Q: So why doesn t it work, and how do we make it work? A: DX design must address three critical issues: 1. Stratified/Wavy Flow at low temperatures - Aluminum tubes w/ proprietary ID enhancement 2. Management/removal of water - Use only dry high pressure liquid - Trap and remove at the accumulator 3. Refrigerant distribution - Colmac Tank Distributor Schaffhausen, 28 June 2013 Page 6

7 Case Study # sq m/2.7 MW Public Cold Store Study (Welch 2013) compares conventional pumped ammonia vs. DX ammonia Project Description: Type of Facility: Public Refrigerated Warehouse Location: Southeastern USA Overall Dimensions: 122 m x 85 m (10370 sq m) Total Refrigeration Load: 2650 kw -23 deg C Freezer 995 kw (6) x -37 deg C Blast 229 kw ea +7 deg C 280 kw 2-Stage Screw Compressors w/ Economized High Stage Schaffhausen, 28 June 2013 Page 7

8 Case Study # sq m/2.7 MW Public Cold Store DX Value Proposition: Reduce ammonia charge in occupied spaces Bring system charge under lbs threshold Energy efficient low side piping Recirculation vessels and pumps eliminated Wet suction lines eliminated (DX = dry suction) Example: DN100 (4 ) x deg C x 30 m Wet Suction (3:1) dp/dt = bar / 0.72 deg C Dry Suction dp/dt = 0.16 bar / 0.26 deg C Concl: Reduction in compressor power = 1.3% (Dry vs Wet) First cost must be competitive with pumped ammonia system Power consumption must be same or less than pumped ammonia system Schaffhausen, 28 June 2013 Page 8

9 Case Study # sq m/2.7 MW Public Cold Store 400' 8' 16' TYP (15) 10' AISLES 250' BLAST CELLS 2 WIDE X 8 DEEP 14' X 35' ROOM (6) PLCS 30' MACHINE ROOM 60' DOCK - (20) 8' WIDE TRUCK DOORS ON 14' CENTERS EVAPORATORS Schaffhausen, 28 June 2013 Page 9

10 Case Study #1 Pumped Ammonia PID HOT GAS 93 psig (60 F SAT) CONDENSER CONDENSER CONDENSER TSR T-S RECEIVER TSS OIL POT INTERCOOLER -20 F WET SUCTION FREEZER 28 F 42.6 psig SS-ECON FREEZER HIGH STAGE OIL POT OIL POT 28 F WET SUCTION -45 F WET SUCTION BLAST BLAST BOOSTERS OIL POT SOLENOID VALVE THERMAL EXPANSION VALVE PRV VALVE Schaffhausen, 28 June 2013 Page 10 DRAIN VALVE 3-WAY VALVE HAND EXPANSION VALVE

11 Case Study #1 DX Ammonia PID HOT GAS 93 psig (60 F SAT) CONDENSER CONDENSER CONDENSER TSR T-S RECEIVER FREEZER TSS OIL POT INTERCOOLER -20 F SUCTION 108 lbs/min -20 F 3.6 psi 18.3 psia 28 F 42.6 psig TO HOT GAS SS-ECON FREEZER HIGH STAGE +28 F SUCTION OIL POT 58 psig (40 F SAT) DX SUBCOOLER OIL POT SC-MPL BLAST -45 F SUCTION 153 lbs/min -45 F 9" Hg 11.7 psia BLAST BOOSTERS OIL POT STILL XFER SOLENOID VALVE THERMAL EXPANSION VALVE PRV VALVE Schaffhausen, 28 June 2013 Page 11 DRAIN VALVE 3-WAY VALVE HAND EXPANSION VALVE

12 Case Study #1 DX Evaporator Valve Group Schaffhausen, 28 June 2013 Page 12

13 Case Study # sq m/2.7 MW Public Cold Store Ammonia Charge, lbs Thermosyphon O/C Glycol O/C Component Recirculated DX % Reduction DX % Reduction Blast Evaporators & Valve Groups % % Blast Headers % % Blast Vessel & Trim % % Freezer Evaporators & Valve Groups % % Freezer Headers % % Freezer Vessels & Trim % 50 96% Dock Evaporators & Valve Groups % % Dock Headers % 8 97% Intercooler & Trim % % Compressors & Headers % 174 0% Condensers & Headers % % Thermosiphon Receiver, Min ch % 0 100% T/S Piping & HX % 0 100% Receiver (Glycol Oil Cooling), 30" X 12' 0 0 N/A 115 N/A Total % % Schaffhausen, 28 June 2013 Page 13

14 Ammonia Charge, kg Case Study # sq m/2.7 MW Public Cold Store 8000 Distribution of Ammonia Charge Pumped DX Low Side Equipment & Pipes Compressors & Headers High Side Equipment & Pipes Oil Cooling Total Schaffhausen, 28 June 2013 Page 14

15 Case Study # sq m/2.7 MW Public Cold Store Conclusions: Greatest ammonia charge reduction is in the evaporators (occupied spaces) and low side vessels System ammonia charge: Pumped Bottom Feed DX lbs (6886 kg) 4125 (1875 kg) DX design is well under the lbs threshold. Compared to pumped design: First cost is same or less. Power consumption is same or less. Schaffhausen, 28 June 2013 Page 15

16 Case Study # sq m/402 kw Food Service DC Client: Supplying Australian market with Hospitality Equipment, Fresh Produce, and Food Service products. Design/Build Contractor: Innovative ammonia refrigeration solutions specialist. DX Ammonia Technology Provider Schaffhausen, 28 June 2013 Page 16

17 Case Study # sq m/402 kw Food Service DC 60+ Refrigerated Food Service facilities currently using HFC refrigeration systems. Bibra Lake WA Schaffhausen, 28 June 2013 Page 17

18 Case Study # sq m/402 kw Food Service DC 1. HFC to Ammonia Conversion Value Proposition: Eliminates exposure to Australian Carbon Equivalent Refrigerant Levy Significant reduction in power consumption 2. DX Ammonia Value Proposition: Significant reduction (30 to 50X) in ammonia charge in occupied spaces. Energy efficient low side piping Recirculation vessels and pumps eliminated Wet suction lines eliminated (DX = dry suction) First cost is competitive with pumped ammonia Power consumption is same or less compared to pumped ammonia Schaffhausen, 28 June 2013 Page 18

19 Case Study # sq m/402 kw Food Service DC Project Description: Type of Facility: Food Service Distribution Centre Location: Perth (Western Australia) Overall Dimensions: 84 m x 54 m (4536 sq m) Total Refrigeration Load: 402 kw -25 deg C Freezer 174 kw +16 deg C Flour 11 kw ea +4 deg C Chiller 51 kw +4 deg C Annex 166 kw 2-Stage Ammonia w/ VFD Reciprocating Compressors vs Split 1- Stage Air-Cooled HFC Packaged Units Schaffhausen, 28 June 2013 Page 19

20 Case Study # sq m/402 kw Food Service DC Schaffhausen, 28 June 2013 Page 20

21 Case Study # sq m/402 kw Food Service DC Fluid GWP Non-CO 2 e Import Levy [$/kg] Carbon Equivalent Refrigerant Levy CO 2 e Levy Component [$/kg] Total Levy [$/kg] Total fluid cost [$/kg] NH R404A Source: S.Jensen. Carbon Equivalent Refrigerant Levy the Australian Experience. eurammon Conference Nurnberg Estimated Refrigerant Costs Fluid NH3 R404a Initial Refrigerant Charge, kg Initial Refrigerant Cost, $ Annual Average Loss, %/a 1 16 Annual Loss, kg Annual Cost Due to Loss Incl Carbon Levy, $/a Schaffhausen, 28 June 2013 Page 21

22 Case Study # sq m/402 kw Food Service DC Estimated Annual Energy Costs NH 3 vs R404a Fluid NH 3 R404a Annual energy consumption, MWh/a Power factor Electric motor efficiency Unit electrical energy costs, $/MWh Annual electricity costs, $/a 228, ,702 CO 2 emissions per kwh, kg/kwh Annual CO 2 emission, tonne/a Carbon Tax charge, $/tonne CO 2 e Annual emission penalty, $/a 32,752 53,567 Annual energy cost incl emission penalty, $/a 261, ,269 Annual water consumption and treatment 13,600 0 Source: S.Jensen Ammonia in Traditional HFC Territory: How Does It Compare? IIAR, Annual Meeting Proceedings, Colorado Springs, CO Schaffhausen, 28 June 2013 Page 22

23 Case Study # sq m/402 kw Food Service DC Estimated Evaporator Ammonia Charge*, kg Room Name Qty Internal Te, C DX Charge DX Charge, Pumped Charge Pumped Vol (ea), L Factor, kg/l kg Factor, kg/l Charge, kg Flour Chiller Freezer Annex Total *Source: B. Nelson DX Ammonia Piping Handbook Colmac Coil Manufacturing Inc., Colville, WA Schaffhausen, 28 June 2013 Page 23

24 Case Study # sq m/402 kw Food Service DC Conclusions: Exposure to Australian Carbon Levy eliminated. Initial cost saving of $65150 for refrigerant Annual cost savings of $10740 from reduced refrigerant loss Annual operating costs reduced by approx. $152,500/a. Simple payback (2-Stage DX NH3 vs 1-Stage Air-Cooled HFC) estimated at 3-4 y. Ammonia charge in occupied spaces reduced from 600 kg (pumped) to 20 kg (DX). Schaffhausen, 28 June 2013 Page 24

25 References Gooseff, A. Horton, J, Ammonia as the Sustainable Refrigerant: An Ammonia- Halocarbon Comparison, International Institute of Ammonia Refrigeration (IIAR), 30 th Annual Meeting, Colorado Springs, CO. Jensen, S Carbon Equivalent Refrigerant Levy the Australian Experience. eurammon Conference, Nurnberg Jensen, S Ammonia in Traditional HFC Territory: How Does it Compare?, International Institute of Ammonia Refrigeration (IIAR), 35 th Annual Meeting, Colorado Springs, CO. Nelson, B Thermodynamic Effects of Water in Ammonia on Evaporator Performance, International Institute of Ammonia Refrigeration (IIAR), 32 nd Annual Meeting, San Diego, CA. Nelson, B DX Ammonia Piping Handbook, Colmac Coil Manufacturing Inc., Colville, WA. Welch, J DX Evaporator Installation Final Report Iwelch Engineering Corporation. Ponte Vedra Beach, FL Schaffhausen, 28 June 2013 Page 25

26 Reducing Ammonia Charge in Industrial Refrigeration Using DX Thank you! Schaffhausen, 28 June 2013 Page 26