UtilitiesUtilities
14 October 200814 October 2008
Martin Nordby, Gordon Bowden
LSST Camera Systems Integration
2
ContentsContents
• Overview of services to camera
• Operating parameters for services
• Routing of utility lines
• Facility design overview
• Current issues
LSST Camera Systems Integration
3
Services to the CameraServices to the Camera
• Heat extraction and environmental control
– Cryogenic system
– Cryogen vapor return
– Purge system
– Fluorinert cooling system
• Operations and control
– Compressed air
– Cryostat backing vacuum
– Valve box backing vacuum
– Power
– Alarm signals out
– Data and control fiber lines
Utility Trunk
ValveBox
Camera Body
Cryostat
Trunk Fan Unit
Cold Plate
Cryo Plate
Camera Fan Unit
5X disconnect for Camera removal
2X bayonet disconnect for
Camera removal
AVacuum pumps
Back end vacuum
Focal Plane vacuum
L3 O-ring pump groove
Feedthrough flange pump
groove
L3 gasket pump groove
P
P
P
P
Cryostat vacuum Valve Box vacuum
Relief valve return
Compressed air
Nitrogen gas purge
Cryogen
LSST Camera Systems Integration
4
Cryogenic System Operating ParametersCryogenic System Operating Parameters
• Cryogenic cooling
– Closed-loop temperature control of cryo plate and cold plate
– Nominal temperature: -140oC
– Total capacity: 1400 W • FEE process heat: 600 W (cryo plate)• Cryo plate heat leaks: 16 W (cryo plate)• IR heat load: 98 W (cryo plate)• RCC process heat: 400 W (cold plate)• Cold plate heat leaks: 36 W (cold plate)• Transfer line losses: 250 W
– Minimum flow rate: 1 kg/sec
• Cryogen properties
– Cryogen: refrigerant R124
– Design mass flow rate: 1 kg/sec
– Design volumetric flow rate: 8.65 gpm
– Specific weight: 1.84
– Viscosity at -145oC: 0.012 kg-m/s(compare with water: 0.001 kg-m/s)
• Flow configuration
– Elevation difference: 93 ft (28 m)
– Total circuit length: 712 ft (217 m)
– Max pressure head: 87 psi
– Total line losses: 95 psi
Cold PlateCold Plate
Cryo PlateCryo Plate
LSST Camera Systems Integration
5
Camera Utilities Operating Parameters (1)Camera Utilities Operating Parameters (1)
• Cryogen relief valve
– Purpose• Exhaust of vaporized R124 refrigerant during cool-down, line purging, or over-pressure condition• Prevents venting to dome air
– Design parameters• Must handle 1 kg/sec flow rate at 100:1 expansion ratio, with < 2 atm back-pressure• Insulated to prevent condensation• Lines will run warm during normal operation
• Nitrogen gas purge
– Purpose• Temperature and humidity control of Camera and Utility Trunk volumes• Preserve clean environment in the Camera volume• Supply for emergency back-fill of cryostat vacuum volume
– Design parameters• Minimum 260 STP-liter capacity at 30 psi min pressure, for emergency back-fill• Closed-loop temperature controlled flow with re-heaters• Nominal temperature: dome temperature• Minimum flow rate: 2 L/sec of 30 psi nitrogen
• Fluorinert
– Purpose• Closed-loop temperature control of support electronics crates in the Utility Trunk
– Design parameters• Nominal temperature: dome temperature – T • 2700 W total capacity = 2400 W of pump heat + 300 W electronics heat• Minimum flow rate: 1 gpm
LSST Camera Systems Integration
6
Camera Utilities Operating Parameters (2)Camera Utilities Operating Parameters (2)
• Compressed air
– Purpose• Power source for pneumatically-operated remote shut-off valves for cryogenic and fluorinert systems
– Design parameters• Filtered, oil-free air• ~75 psi minimum pressure• Minimum flow rate: 2 L/sec of 75 psi air
• Cryostat backing vacuum
– Purpose• Pumps down the cryostat from ambient, using roughing pumps on the ground• Provides mechanical backing vacuum for turbo-pumps during normal operation
• Valve box backing vacuum
– Purpose• Pumps down the valve box to prepare it for cool-down• Independent of cryostat system, allowing the cryostat to stay cold while the camera is being de-/re-mounted
from/to the telescope
LSST Camera Systems Integration
7
Camera Utilities Operating Parameters (3)Camera Utilities Operating Parameters (3)
• Data and control fiber lines
– 62 fiber lines, total• Science data lines: 25 pairs of optical fibers• Guider, WFS data lines: 4 pairs of optical fibers• Control lines: 2 pair of optical fibers
• Alarm
– Direct copper lines for camera protection circuits
– Provide hardware enable/disable signals
• Power
– 6 kW on-camera capacity; 120V single phase (2x margin)• Cryostat electronics: 950 W• Support electronics: 250• Pumps: 2400 W
LSST Camera Systems Integration
8
Routing of Services to the CameraRouting of Services to the Camera
Service Qt'yRigid
Line SizeFlex
Line SizeDetails Restrictions Usage
Cryo cooling 2 3-1/2" O.D.4" O.D. bellows w/ over-braid
Vacuum-insulated 1-1/2" I.D. flex hose
23" min bend radius
Cooling for cryo plate and cold plate
Cryogen relief valve return line
1 3" O.D. 4" O.D. flex2" O.D. line with foam insulation
2" O.D. line with foam insulation
Return path for vapor
Nitrogen gas purge 2 1-1/2" O.D. 3" O.D. flex2 L/sec @ 30 psi max flow rate; 1/2" lines with foam insulation
Capable of 60 second back-fill of cryostat
Fluorinert 2 1-1/2" O.D. 1-1/2" O.D.1/2" O.D. lines, foam insulated for 1 gpm flow
Room-temp cooling of support electronics
Compressed air 1 1/2" O.D. 1" O.D. flex 2 L/sec @ 75 psi shop air Clean, oil-freePneumatically-actuated cryo valves
Cryostat backing vacuum
1 3" O.D.4" O.D. bellows w/ over-braid
Stainless steel tubing23" min bend radius
Pump-down line to evacuate cryostat and back turbo-pump
Valve Box backing vacuum
1 3" O.D.4" O.D. bellows w/ over-braid
Stainless steel tubing23" min bend radius
Pump-down line to evacuate cryostat and back turbo-pump
Data and control fiber lines
2 1/2" O.D. 1/2" O.D.Sumitomo 36-fiber bundle, jacketed
10" min bend radius
Science data output; camera control I/O
Alarm 1 1/2" O.D. 1/2" O.D. 25-pair 26 AWG cableHard-copper alarm and safety signals
Power 2 3/4" O.D. 3/4" O.D.Belden 4-conductor shielded, jacketed 10 AWG cable
7" min bend radius
Camera power
Total cross-sectional areas (in^2):Cross-sectional area 25.50 33.00w/ 33% margin 34.00 44.00w/ 50% packing fraction 68.00 88.00 = 6" x 16" rectangular package
LSST Camera Systems Integration
9
Routing of Camera Utility and Service LinesRouting of Camera Utility and Service Lines
test/staging mirror coating
data control office
cable wrap
platform lift shaft
telescope pier
entry mech.
cleanroom
whiteroom
camera utilities
Suite of camera maintenance rooms on east side of service & ops building
Approximate routing of utility runs from cameraon telescope:
On telescope mount & rotator to camera 76’+34’
To camera utility room - 281’+10% for indirect routing = 310’ (location of Polycold units)
From camera utility room to:- clean room - 30’ - white room - 50’- test/staging area - 80’
Elevation drape Flex Line 20’+5’ margin
From elevation drape to azimuth wrap 40’
Azimuth drape Flex Line 50’+20’margin
Through enclosure to S&O building 10’+ 40’
In building to camera utility equipment 30’
Section through Enclosure & Support BuildingSection through Enclosure & Support Building(showing routing of camera coolant lines)(showing routing of camera coolant lines)
Elevation drape to spider 55'Spider Length (custom pipe) 12‘ + 2x2’ FlexCamera Cable Rotator (flex line) 30’ +Wrap to Camera (flex line) 9'
Flex line: 50 + 20 + 25 + 4 + 30 = 129’Hard line: 30 + 50 + 40 + 76 =196’
FlexHard
LSST Camera Systems Integration
10
Ground FacilityGround Facility
• All camera utilities and service lines are routed to the Utility Room
– All support hardware for camera operations is located in the Utility room
– This includes UPS’, SDS and process controllers
• Total power estimate
– 66 kW needed• 51 kW for 3 Polycold units• 4.5 kW for pumps• 2.4 kW to camera for pumps• 1.2 kW to camera for power• 1 kW facility electronics• 3.9 kW miscellaneous
– We may be able to go to 2 Polycold units….
• All systems assumed to be water cooled, using facility chilled water
Ground Facility
N2
Polycold
R124 150KReservoir Heat X’er
N2
Gas head on reservoir
Polycold
Ground facilityinsulating vac
On-telescopeinsulating vac
Cryostat vacbacking pump
Pump 1Pump 2
Purge gas
Supply
Return
Facility Chilled Water
De
-Ga
sser
Cryogen Vacuum Tank
He
ate
r
Polycold
N2 Purge gas
He
ate
r
Pump Vacuum Tank
Compr air
Cryostat vacuumValve Box vacuum
Relief valve return
Compressed airNitrogen gas purge
Cryogen
LSST Camera Systems Integration
11
Camera Utilities Reliability and Fault ToleranceCamera Utilities Reliability and Fault Tolerance
• Redundancy/single-point failures
– No moving parts or valves in the cryostat• Fluid flow channels are in parallel• We have not investigated whether these 3 parallel channels are 2-for-3 redundant
– Valve box contains valves and flow instrumentation—this is presumably where problems would occur
• This is in a separate vacuum• The valve box can be dis-assembled in situ, but it is not yet clear if we can do this on the telescope
– Ground facility includes redundancy of critical components• Polycolds: 2-for-3 redundancy• Cryo pumps: either 1-for-2 redundancy or a “cold” spare ready for turn-on
• Servicing and repair concepts
LSST Camera Systems Integration
12
Open IssuesOpen Issues
• Cryo cooling technology
• Cryo system design details
• Transfer line design, routing, and installation