eurammon Symposium · PDF fileeurammon Symposium 2016 Requirements of compressors in CO 2...

eurammon Symposium 2016

Requirements of compressors in CO2 plants

of the latest generation in the retail industry

Manuel Fröschle (GEA Bock)

Schaffhausen, 23rd/24th June, 2016

Schaffhausen, 23rd / 24th June, 2016

F-Gas regulation – Europe

Phase down

21% CO2 eq. (2030)

High reduction in 2018

low GWP refrigerants

Refrigerant costs

Availability

Quota Leakage

Qualification

Prohibitions

GWP ≥2500 (2020)

GWP ≥150 (2015, 2020, 2022)

GWP ≥ 750 (2025)

Service (2020)

Service stop (2030)

R404A, R507

R404A, R507


Solutions with low/medium GWP refrigerants

HFO blends GWP >750

Already known technologies but further developments for various applications

necessary

Qualification is essential

Proper handling of flammability at hydrocarbon and additional toxicity at

ammonia have to be considered

The advantage of CO2 results in high potential of the refrigerant at different

applications and also in warm climate zones

Flammability has to be considered

and further investigated

Solution for small capacities

Often only mid term solutions (too high GWP)

Further environmental influences

have to be considered

and further investigated

Natural refrigerants

Often only mid term solutions (still too high GWP)

Long term solutions

HFO refrigerants and further

refrigerant blends with medium

and low GWP < 750 or < 150


System development with CO2 as refrigerant

VSD VSD

CO2 Booster Systems:

• Cooling: Only LT or MT & LT

• Heat recovery (hot water & heating)

+ Evaporator (outside) as heat pump function

• Air conditioning evaporator (AC)

Options to increase efficiency of the system:

• Adiabatic cooling of the gas cooler (spray system)

• Sub-cooler (separated system after gas cooler)

• Parallel compression

• Ejectors (vapor/liquid) + parallel compression

Heat recovery

LT evaporator

MT evaporator

LT evaporator

Main compressors Parallel compressor

Flash gas bypass

AC evaporator


Key features of CO2 compressors

Designed for CO2 pressure requirements Stand still & operating pressures

Wide operating conditions

Wear resistance of the drive gear

for highest requirements High refrigerant solubility in the oil

Capacity control & part load requirements

(changing operating conditions)

Low oil carry over

Minimum pulsations & vibrations

Highest efficiency


CO2 booster system with parallel compression

flash gas

x = 14 %

40°C

15°C

COP comp.

@ 40°C → 2,31

@ 15°C → 11,0

COP comp.

@ 40°C → 1,57

@ 15°C → 5,37

flash gas

x = 46 %

to_LT = -35°C (12,0 bar)

to_MT = -10°C (26,5 bar)

tm = 3°C (37,7 bar)

main compressor

parallel

compressor


Comparison main compressor (to = -10°C) with

parallel compressor (to = +3°C)

@ 35°C (90 bar)/ 10 K/ Compressor: HGX34/210-4 S CO2 T

Power consumption at same mass flow

Compressor efficiency at parallel compression



0,4

0,5

0,6

0,7

0,8

0,9

1

1 2 3 4 5 6

Vo

lum

etr

ic &

is

en

tro

pic

eff

icie

ncy

[-]

Pressure ratio [-]

3°C/40°C (101 bar) (Parallel C.)

-10°C/40°C (101 bar)

3°C/15°C (50,9 bar) (Parallel C.)

-10°C/15°C (50,9 bar)

Average volumetric & isentropic efficiency

@ tga = 40°C

@ tc =15°C

volumetric

• Factor for refrigerant

mass flow

volumetric efficiency

isentropic

• Factor for compressor

power consumption

isentropic efficiency



40°C

35°C

30°C

25°C

20°C

15°C

COP within operating limits of

compressor:

HGX34/210-4 S CO2 T (18,2 m3/h @ 50 Hz)

5,4

4,2

3,3

2,5

1,9

1,6

COP main compressor

2,3

3,0

3,9

5,7

7,8

11,0

COP parallel compressor

www.asercom.org

2,9

12,1

tg_out

tc

to

Performance data proofed by

ASERCOM


Efficiency increase due to new CO2 system technologies

Current feedback from field applications regarding seasonal performance factor :

Standard CO2 booster system +10% +10-20% + parallel compression + Ejectors

Depend on operating conditions and requirements.

Advansor


CO2 booster system with parallel compression

Advantages

Retention of the established CO2 Booster

system with medium pressure separator

Compressor swept volume in the system

can be significantly reduced

Efficient compression of the flash gas from

higher suction pressure

Clear increase of efficiency of system

can be reached

Different technologies for further increase

of efficiency can be combined (air

conditioning evaporator (AC),

several MT levels, ejector…)

Oil management in the system

Capacity control & part load

requirements

Increasing requirements for system control

Increasing system complexity

Challenges


Capacity control at parallel compression with VSD

High pressure stage:

Low temperature stage:

(to = -35°C)

(25)30-70 Hz 50 Hz 50 Hz

Pc_sub.

Qo_LT

Qc_LT

20-70 Hz 20-70 Hz 50 Hz

Pc_trans.

Qo_MT + Qc_LT

main compressor (to = -10°C)

50 Hz

parallel compressor

(to = +3°C)

Pc_trans.

Qc_all


Compressor Requirements – Capacity Control with VSD

1

start / stop

%

140

120

100

80

60

40

0

Hz

70

60

50

40

30

20

compressor 1 with

frequency converter 20-70 Hz

Frequency controlled compressor

Co

ntr

ol ra

ng

Min. 20 Hz is possible as a result

using an oil pump

and optimized compressor design


Compressor requirements – capacity control with VSD

compressor 1 with frequency

converter 20-70 Hz

compressor 2-4 without frequency

converter (50 Hz)


Compressor requirements – oil carry over

• General high solubility of CO2 in the oil

• Optimized oil management in compressor necessary to reduce high oil carry over, particular under

following conditions:

• High evaporating temperature with high mass flow (e.g. parallel compression, heat pump applications…)

• High compressor frequency (capacity control with VSD > 50 Hz)

Optimized oil management system in

transcritical GEA Bock CO2 compressors:

• Separation of oil and refrigerant

• Oil return via suction gas to the compressor

oil sump is ensured

Reduction:

Oil carry over at to = 3°C (37,7 bar (abs.)) @ 50 Hz


Food cold chain with refrigerant CO2

Supermarkets, Hypermarkets &

Convenience stores

Food production Freezer Cold storage


Food production

MT: 550 kW (-5° C)

6 x HGX46 CO2 T (transcritical compressors)

LT: 12 kW (-30° C)

2 x HGX12e CO2 (subcritical compressors)

+ Heat recovery (350 kW)

Information regarding CO2 booster

Rack system: SCM Frigo

Installer: Van Cleven

End-user: Rabbit (Convenience Food)

Application: Food processing (production)


Food production – fishing (Freezer)

LT ref. capacity: 240 kW (-50° C)

1-stage: 5 x HGX46 CO2 T (transcritical compressors)

2-stage: 6 x HGX46 CO2 T (transcritical compressors)


Rack system: Kuldeteknisk AS

End-user: Nordic wildfish AS (Boat: Roaldnes)

Application: Fisher boat with CO2 freezer

36 t fish per day (@ 25°C water temperature)

Higher freezing capacity of around 25 %

with higher freezer speed with CO2 compared to R22

→ higher product quality

+ 20 % less volume of the refrigeration system


Cold storage

LT: 60 kW (-32° C)

1 stage: 3 x HGX22e CO2 (subcritical comp.)

2 stage: 3 x HG34 CO2 T (transcritical comp.)

+ Heat recovery


Rack system: Christof Fischer

Installer: Wallburg Kältetechnik GmbH

End-user: Aldinger GmbH + Co. KG

Application: Frozen convenience food


Hypermarket – Cash and Carry

MT1 (+ AC, + flash gas): 85 kW (+2° C)

2 x HGX34 CO2 T (transcritical comp.)

MT2: 245 kW (-8° C)


LT: 128 kW (-32° C)

3 x HGX34e CO2 (subcritical comp.)

+ Heat recovery 65 kW (+20/+60°C)


Rack system: Advansor

Installer: kke GmbH

End-user: Metro


Convenience store (Japan)

MT: 30 kW (-10° C)


LT: 7 kW (-40° C)

2 x HGX12e CO2 (subcritical comp.)

+ Heat recovery


Rack system: Nihon Netsugen

Installer: Fukushima Industry

End-user: Aeon

Contact eurammon:

Dr. Karin Jahn | Managing Director

Lyoner Strasse 18

D-60528 Frankfurt

Germany

Phone: +49 (0)69 6603 1277

E-mail: [email protected]

eurammon Symposium · PDF fileeurammon Symposium 2016 Requirements of compressors in CO 2...

Documents

Transcript of eurammon Symposium · PDF fileeurammon Symposium 2016 Requirements of compressors in CO 2...