Low Charge NH 3 Systems in Practice

Transcription

1 eurammon Symposium 2016 Low Charge NH 3 Systems in Practice Stefan S. Jensen Schaffhausen, 23 rd /24 th June, 2016

2 Overview - Five new Australian low charge NH 3 systems - Smooth & internally enhanced evaporator tubes - Two different NH 3 injection control methods (SH & SH/X) - Two different interconnecting piping materials (Fe & SS) - Two different oil separation/return methods - 40 kw < LT < 180 kw; 60 kw < HT < 250 kw - NH 3 inventories kg - Recorded energy performances in kwh/m 3 *a Schaffhausen, 23 rd / 24 th June, 2016 Page 2

3 The five NH 3 plants - 43,000 m 3 facility in Perth, WA freezer, chiller & ante room - 10,000 m 3 facility in central NSW freezer, chiller & ante room - Food processing facility, Brisbane, QLD freezer only - Retrofit in meat processing plant, Brisbane freezer only - 43,000 m 3 facility in Melbourne, VIC freezer, chiller, ante room & temperature controlled area Schaffhausen, 23 rd / 24 th June, 2016 Page 3

4 The third NH 3 plant Engine room Freezer, -25 C 42 m 40 kw 40 kw Schaffhausen, 23 rd / 24 th June, 2016 Page 4

5 So what is new here? - Overall charge reduction from kg/kw to kg/kw; NH 3 inventory in air coolers times less than LR; potential NH 3 concentration in warehouse <150 ppm - Specific energy consumption values in kwh/m 3 *a are 0.45 to 0.60 times the values recorded by CEC in 2008 (163 RDC s) - Quality based refrigerant injection control (0.95 < x < 0.99) - High pressure liquid based oil separation combined with automatic oil return; oil content < 1 ppm - Hot gas defrost sequence with two hot gas supplies Schaffhausen, 23 rd / 24 th June, 2016 Page 5

6 So what is new here? - Internal surface enhancement promoting capillary action - Conventional, Küba style and tank distributors - Interconnecting 304SS pipe lines with times lower absolute roughness than carbon steel - Infiltration and frost management - Variable frequency drives on everything - Modern reciprocating compressors with low oil carry-over - Injection control based on evaporator exit quality enabling exceptionally low entering temperature differences Schaffhausen, 23 rd / 24 th June, 2016 Page 6

7 The 3 rd NH 3 plant: Compressors Low temperature accumulator Intercooler with NH 3 /glycol PHE Variable frequency drives Schaffhausen, 23 rd / 24 th June, 2016 Page 7

8 Frost management: Desiccant drier Schaffhausen, 23 rd / 24 th June, 2016 Page 8

9 The evaporators Combined superheat and quality based DX control: X Sensor Distributor Schaffhausen, 23 rd / 24 th June, 2016 Page 9

10 The injection control What is quality based refrigerant injection control? Electronically controlled refrigerant injection based on refrigerant quality at evaporator exit The dielectric spectroscopy (capacitance) measurement method uses the difference in dielectric properties of gases and liquid Quality or x sensor Schaffhausen, 23 rd / 24 th June, 2016 Page 10

11 The valve station Hot gas Liquid Suction Condensate Condensate HBDX To drainer Schaffhausen, 23 rd / 24 th June, 2016 Page 11

12 Performance SH>0 & X<1 at the same time X OUT t ROOM TXV SH Schaffhausen, 23 rd / 24 th June, 2016 Page 12

13 Performance Evaporator performances: - Positive superheat for 0.95 < x < kw (25.5 TR) at -19 C air on and -24 C SST (prediction 81 kw at 7.7K ETD) - Holding at -22 C for C SST - X control more stable than SH Schaffhausen, 23 rd / 24 th June, 2016 Page 13

14 Oil management Schaffhausen, 23 rd / 24 th June, 2016 Page 14

15 Specific Energy Consumption Energy efficiency State of the art, low charge, dual stage NH 3 DX systems with SH/X control 2001 (AC) Source: California Energy Commission 2008 Schaffhausen, 23 rd / 24 th June, 2016 Page 15

16 NH 3 charge reduction 304SS System charge 480 kg; LT/HT 170/250 kw Low charge: kg/kw Conventional liquid overfeed: 3-4 kg/kw Schaffhausen, 23 rd / 24 th June, 2016 Page 16

17 Business case - Retrofit from multiple air cooled HFC units to central low charge NH 3 plant with glycol loop for medium temperature - Investment ~A$1,900,000 (refrigerated volume ~21,000 m 3 ) - Estimated SEC reduction from 143 to 38 kwh/m 3 *a - Annual cost savings A$400,000 (energy & maintenance) - Current monthly electricity account A$43,000-A$48,000 Simple pay-back k$1900/k$400 < 5 years Schaffhausen, 23 rd / 24 th June, 2016 Page 17

18 Business case $42,000/month Conversion cost $2,000,000 $13,500/month ROI = (42,000-13,500)*12/2,000,000*100=17% Schaffhausen, 23 rd / 24 th June, 2016 Page 18

19 Discussion - ~20% return for retrofits of HFC plants with new low charge NH 3 (based on unit electrical energy cost $200-$300/MWh) - ~30-50% return on Δ investment between new low charge NH 3 and new industry standard HFC (HFC=0.6*NH 3 ) - NH 3 inconveniences gradually minimized/eliminated (oil drainage, moisture, operators, specialist maintenance) - Low charge NH 3 costs about the same as NH 3 liquid overfeed - Lower than expected energy bills drive market acceptance ONCE YOU GO AMMONIA YOU NEVER GO BACK Schaffhausen, 23 rd / 24 th June, 2016 Page 19

20 Contact eurammon: Dr. Karin Jahn Managing Director Lyoner Strasse 18 D Frankfurt Germany Phone: +49 (0)