CO 2 radial piston compressor (transcritical)

Transcription

1 CO 2 radial piston compressor (transcritical) At a glance Operating limits and performance data Technical data Dimensions and connections Scope of supply

2 Radial piston compressor (transcritical) - At a glance Bock has developed this new radial piston compressor with Obrist Engineering GmbH, who has also worked on the development of CO 2 compressors for a long time. Additionally, the RKX is a radial piston compressor, providing a very compact arrangement. It is a compressor with future potential - ideal for small to medium capacities. The compact engineering design, universal possibilities for installation (vertically or horizontally) as well as the 6-cylinder construction that is radially arranged on one level, result in completely new dimensions for the working range and potential for development of the compressor itself (potential operating pressure up to 130 bar). Important Information --Transcritical CO 2 applications are still in the development phase --They require a completely new kind of system and control --They are not a general solution for the substitution of F-gases --We specifically point out that all information in this chapter has been made based on our current level of knowledge and may change at any time due to further development. -- Compressors can only be made available for selected projects Available models RKX26/31-4 CO 2 T RKX26/31-2 CO 2 T Displacement 50 Hz 2,7 m 3 /h ( /min) 5,4 m 3 /h ( /min) CO 2 as a refrigerant Within refrigeration technology, carbon dioxide (CO 2 ) is known by the name R744 and has a long history. It is a colourless gas which liquefies under pressure and has a slightly acidic smell and taste. Carbon dioxide has no ozone depletion potential (OD=0) and a negligible direct effect on global warming (GW=1) when used as a refrigerant in closed systems. It is not combustible, is chemically inactive and heavier than air. Carbon dioxide has a narcotic and asphyxiating effect on humans only at higher concentrations. As carbon dioxide is less energy efficient than other refrigerants, recently work has particularly concentrated on optimising plant technology for specific applications. Carbon dioxide is available naturally in large quantities. Special features of CO 2 transcritical Based on the high CO 2 pressure and the low temperature of the critical point of 31 C (74 bar), transcritical operating conditions occur at higher temperatures at the heat exchanger. In this case, in comparison to subcritical applications, the refrigerant CO 2 can no longer be condensed. In this case, the refrigerans is heated in a gas cooler. The temperature and the pressure are dependent on each other, compared to the subcritical operation. A special feature in these operating points is the necessary regulation of the high pressure at the so-called optimal high pressure. In doing this, the greatest possible enthalpy difference at the evaporator and the lowest possible power consumption of the compressor should be reached. In this way, the maximum coefficient of performance (CO) of the system is achieved. An additional valve with intelligent control after the high-pressure heat exchanger is needed for this in the system. For additional technical data, see Bock software = 35 C = 40 C = 45 C = 50 C = Gas cooler outlet temperature Limit conditions: isentrope compression Evaporation pressure = 40 bar with internal heat exchanger 124 I

3 Radial piston compressor (transcritical) - At a glance Special Features --Simple total construction, aligned to the special requirements in the transcritical sector --Only two surface seals on the entire compressor (housing cover, electrical terminal board) --ot-shaped, closed housing made of spheroidal cast iron for maximum pressure strength --Complete power train integrated in the housing, no cylinder cover required -- Only a few small high-pressure compartments --Valve operation according to the uniflow principle, the suction gas is pushed in one direction through the piston and is thus compressed. There are no alternating gas movements and a minimum amount of gas pulsation --Centrifugal lubrication with integrated oil separation --Excellent operating characteristics radial arrangement of six cylinders on one level --Well dimensioned drive motors, partially suction gas cooled, in 2 and 4 pole versions (2.900 and /min) --Suction and discharge connections using screwed cutting ring joints for steel pipes (without shut-off valves) --Decompression valves for the suction and pressure area -- Electrical connection box to I65 with Bock M motor protection Type key Radial piston compressor (transcritical) RKX26 / 31-4 CO 2 T Transcritical CO 2 version Number of poles Swept volume Number of cylinders Size Ester oil filling Series 1) 1) RK = Radial piston I 125

4 Radial piston compressor (transcritical) - Operating limits Operating limits RKX26/31-2 CO 2 T RKX26/31-4 CO 2 T 1 Unlimited application range t O t Oh p O Evaporating temperature ( C) Suction gas superheat (K) Suction pressure (bar) High pressure (bar) Max. permissible operating pressure (L/H) 1) : 90/130 bar 1) L = low pressure H = high pressure 1 RKX26/31-4 CO 2 T min. evaporating temperature t O = -5 C (30,4 bar) Notes Operating limits Compressor operation is possible within the limits shown on the application diagrams. lease note the coloured areas. Compressor application limits should not be chosen for design purposes or continuous operation. erformance data erformance data for CO 2 are based on K suction-gas superheating at 50 Hz. In case of subcritical operating conditions, no liquid undercooling takes place. The performance data for transcritical operating conditions are specified close to the "optimal high pressure". The optimal high pressure is thereby related to an ideal cyclic process. Conversion factor for 60 Hz = 1,2 Notes Oil The compressors are equipped with Bock C120E, a special oil filling, which is available directly from Bock. This is a synthetic ester oil with high thermal load resistance, allowing good mixing solubility with CO 2. It possesses a special additive, which protects the compressors against wear,even when subjected to extreme loads, such as those which exist in CO 2 systems. This oil can be used both in transcritical and subcritical systems. temperature (C ) phase separation concentration (M-% oilinco) I

5 Radial piston compressor (transcritical) - erformance data CO 2 erformance data 50 Hz Type Cooling capacity O [W] ower consumption e [kw] Evaporating temperature C RKX26/31-4 CO 2 T RKX26/31-4 CO 2 T t c C SUBCRITICAL C TRANSCRITICAL Subcritical performance data 50 Hz Relative to K suction gas superheat without liquid subcooling Transcritical performance data 50 Hz Relative to K suction gas superheat , ,85 2, ,90 2,25 2, ,00 2,35 2,55 2, , 2,45 2,70 2,85 2, ,35 2,65 2,90 2,95 2, ,90 3, 3,20 3,30 3, ,60 3,65 3,60 3,50 3, ,00 4,00 4,05 3,85 3, ,75 4,65 4,75 4,30 3,45 t c = Condensing temperature = Gas cooler outlet temperature = ressure at the compressor outlet [bar] The performance data are indicated at a high pressure level, which is close to an optimal high pressure level. Optimal high pressure is thereby related to an ideal cyclic process. Optimal high pressure is outside of the operating limits. erformance data are indicated at maximal possible high pressure. I 127

6 Radial piston compressor (transcritical) - erformance data CO 2 erformance data 50 Hz Type Cooling capacity O [W] ower consumption e [kw] Evaporating temperature C RKX26/31-2 CO 2 T RKX26/31-2 CO 2 T t c C SUBCRITICAL C TRANSCRITICAL ,45 4,45 4,35 4, ,85 4,90 4,85 4,70 4, ,25 5,35 5,35 5,25 5, 4, ,70 5,80 5,80 5,75 5,65 5,45 5, ,15 6,25 6,30 6,30 6,20 6,05 5,75 5, ,45 6,55 6,55 6,50 6,40 6,20 5,90 5, ,20 7,20 7,15 7,30 7, 6,80 6, ,30 8,20 8,00 7,80 7,65 6, ,00 8,80 8,80 8,45 7,85 6, ,00 9,70 9,55 8,85 7,85 Subcritical performance data 50 Hz Relative to K suction gas superheat without liquid subcooling Transcritical performance data 50 Hz Relative to K suction gas superheat The performance data are indicated at a high pressure level, which is close to an optimal high pressure level. Optimal high pressure is thereby related to an ideal cyclic process. t c = Condensing temperature = Gas cooler outlet temperature = ressure at the compressor outlet [bar] Optimal high pressure is outside of the operating limits. erformance data are indicated at maximal possible high pressure. 128 I

7 Radial piston compressor (transcritical) - Technical data RKX Number of cylinders Displacement 50 / 60 Hz Voltage 1 Electrical data 3 Weight Connections 5 Oil Max. power Discharge line Suction line charge consumption DV SV Max. working current 2 2 Starting current (rotor locked) Type m³/h A kw A kg mm mm Ltr. / Y / Y RKX26/31-4 CO2 T 6 2,70 / 3, ,3 / 8, / ,0 RKX26/31-2 CO2 T 6 5,40 / 6, / 23,6 230 / ,0 Oil sump heater V /60 Hz (standard) -- TC heater, W, self-regulating i Explanations: 1 2 Oil sump heater is necessary due to the high CO2 solubility in the oil. Tolerance (± %) relates to the mean value of the voltage range. Other voltages and current types on request. Take account of the max. operating current / max. power consumption when designing contactors, leads and fuses. Switches: Service category AC All data are based on the mean value of the voltage range V / V Y Hz V / V Y Hz Compression joint for steel pipes I 129

8 Radial piston compressor (transcritical) - Dimensions and connections RKX26 CO 2 T RKX26/31-4 CO 2 T RKX26/31-2 CO 2 T ca H L1 DV SV B A ca.300 ca.125 J ca F 4x ca Centre of gravity Dimensions in mm Connections RKX26 CO 2 T SV DV Suction line Discharge line lease refer to technical data! age 129 A Connection suction side, not lockable 1 / 8 " NTF B Connection discharge side, not lockable 1 / 8 " NTF F Oil drain G 1 / 4 " H Oil charge plug G 1 / 4 " J Oil sump heater Ø 15 mm L1 Thermal protection thermostat 1 / 8 " NTF Dimensions for anti-vibration pad Type Ø a b c d mm mm mm mm RKX26 CO 2 T M I

9 Radial piston compressor (transcritical) - Scope of supply Scope of supply RKX26 CO 2 T Semi-hermetic 6 cylinder radial piston compressor with drive motor for part winding start 2- or 4 pole version V / V Y Hz V / V Y Hz Single-section compressor housing Winding protection with TC resistor sensors and electronic motor protection unit Bock M Thermal protection thermostat (TC sensor) I67 Oil sump heater V /60 Hz, W - TC heater, self regulating Oil charge: Bock C120E 1) Compressor decompression valve suction and discharge line Capability of connecting for suction line and discharge line without shut off valves Design in cutting ring version for steel pipes Iners charge 4 anti-vibration pads enclosed 1) Also available as refill unit in 1 or 5 liter packaging I 131