SC1R Cold Box PDR: Process Requirements SC1R Cold Box Preliminary Design Review N Hasan Saturday, November 10, 2018

Presentation Outline CEBAF Cryogenic Load CEBAF 2K Cryogenic Systems - Operating Philosophy - Equipment - Distribution Process Requirements / Considerations - Cold Compressors - 4K-2K Heat Exchanger - Internal Piping Proposed P&I Paths Commissioning Plan Summary SC1R Cold Box PDR: Process Requirements

CEBAF Cryogenic Load Continuous Polarized Electron Beam up to 12 GeV 55 Full Size Cryomodules (C50/C75/C100) 2 Quarter Size Cryomodules Cryogenic Load Split between – a) North LINAC (27.25 CMs) b) South LINAC (25 CMs) c) LERF (3.25 CMs) Prescribed Energy of 1150 MeV/LINAC/pass1 Static Heat in-leak to LHe bath: 22 W/module - Calculated, based on total electric heat applied and TD read-backs RTL Heat in-leak to primary return flow: a) North LINAC 600 W b) South LINAC 600 W c) LERF 250 W Fig. Schematic of CEBAF at 12 GeV 1 Zhang et al., Optimization of the RF cavity heat load and trip rates for CEBAF at 12 GeV, IPAC2017 SC1R Cold Box PDR: Process Requirements

CEBAF Cryogenic Load (contd.) Fig. RF load at each LINAC under different operating conditions 1 RF Heat Load at each LINAC (North / South): approx. 2900 W - can be as high as 3100 W Electric Heat Load (Pressure Compensation): approx. 250 W Total Heat Load per LINAC: approx. 3750 W Flow Required to support Load: approx. 200 g/s - based on approx. 80% quality, 3.0 atm, 4.5 K primary supply flow and 37.5 mbar vapor pressure SC1R Cold Box PDR: Process Requirements

CEBAF Cryogenic Load (contd.) Operating Pressure: 40.0 mbar 6.0 GeV Operations 36.5 – 37.5 mbar 12 GeV Commissioning LINAC Pressure Optimization (Spring 2017 Run) Tests performed at operating pressures ranging from 37.0 mbar to 41.0 mbar 38.5 mbar (maximum allowable) Cavity tuning Fig. North LINAC Operating Pressure and Energy Reach2 2Cryo Pressure / SRF Optimization – Fall 2016, http://devweb.acc.jlab.org/CSUEApps/atlis/task/16566 SC1R Cold Box PDR: Process Requirements

CEBAF 2K Cryogenic Systems – Operating Philosophy 2K Cryogenics for Large Systems: All cold compressors (CEBAF and SNS) Pressure stability demonstrated to be better than +/-0.1 mbar Partial cold compressors (CERN) Pressure stability of +/- 0.3 mbar, which makes the tuning of SRF cavities very difficult and unstable CEBAF 2K Cryogenic Systems: 5 Cold Compressors in Series CC4 Speed maintains flow. CC1-CC3 speed maintained by speed ratio with CC4. CC5 speed maintains constant pressure ratio across. Pump down follows a pre-defined path -CC speed, flow as function of RTL pressure, look-up table, obtained experimentally SC1R Cold Box PDR: Process Requirements

CEBAF 2K Cryogenic Systems - Equipment SCN (SC2)4 Commissioned 1999 (JLab, L’ Air Liquide). 5 Cold Compressors (CC1-CC5). Design max. CC flow ~250 g/s. Design CC return temperature to 4KCB is ~30K. Max. CC Inlet / Outlet Pressures: 28 / 1200 mbar (Pr. ratio 42). 3 NTU 4K-2K Heat Exchanger (added capacity). SCM (SC1)3 Commissioned 1994 (CVI Corp., L’ Air Liquide). Initially 4 Cold Compressors (CC1-CC4), CC5 added later. Design CC flow 236.79 g/s (up to 285 g/s during pump-downs). Design CC return temperature to 4KCB is ~30K. Max. CC Inlet / Outlet Pressures: 28 / 1189 mbar (Pr. ratio 42). Initially 2 NTU 4K-2K Heat Exchanger. Upgraded to 3 NTU later. 3 CEBAF Cold Compressors Characteristics, L’Air Liquide Datasheet 4Design, Fabrication, Commissioning, and Testing of a 250 g/s, 2-K helium cold compressor system, Ganni et al., Proc. of CEC, Vol. 47 (2002) SC1R Cold Box PDR: Process Requirements

CEBAF 2K Cryogenic Systems – Distribution System Two 4.5K Cryo-plants (CHL1, CHL2) Two 2K Cold Boxes (SCM, SCN) Three separate LINACs (NL, SL, LERF) Distribution System – - Separate Header for Each System - Re-configurable (U-Tubes) - Can be Cross-Connected (Valves / U-Tubes) - Helps operating at reduced capacity if needed (during SAD) SC1R Cold Box PDR: Process Requirements

CEBAF 2K Cryogenic Systems – Distribution System CHL1 (4K CBX) CHL2 (4K CBX) SC1M SC2N LERF SL NL Fig. Simplified Schematic of the CHL-LINAC Distribution System (Primary Returns Only, Typical Config.) SC1R Cold Box PDR: Process Requirements

Process Requirements – Cold Compressors Simplified Process Model: Simulated process conditions @ CC1 suction Max. Pump-down Flow: 280 g/s Pump-down Flow Profile: Existing HX Parameters: HX-10 (SCN) NTU 3.0 RTL Heat in-leak: 600 W (per LINAC) Supply Flow Condition: 3.0 atm 4.5 K Considerations - Fully Compressible Flow Single or Dual LINAC Pump-down Fig. Schematic of the 2K system for the Process Model SC1R Cold Box PDR: Process Requirements

Process Requirements – Cold Compressors (contd.) Simulated process conditions @ CC1 suction: Fig.: Simulated CC1 suction temperatures during pump-down Fig.: Volumetric flow requirements at CC1 suction during pump-down SC1R Cold Box PDR: Process Requirements

Process Requirements – Cold Compressors (contd.) Mode of Operation: Maximum Capacity 250 g/s, 1.2 bar ≤ 30 K ~ 3.0 bar, 4.5 K Guaranteed mode of operation. Forms the basis for - a) maximum volume flow (660 liters/sec) b) maximum operating speed For comparison – JLab SC2: 580 liters/sec FRIB (Upgrade): 640 liters/sec LCLSII: 580 liters/sec ≤ 3.6 K ≤ 28.0 mbar HX-10R SC1R Cold Box PDR: Process Requirements

Process Requirements – Cold Compressors (contd.) Mode of Operation: Nominal Capacity 200 g/s, 1.2 bar ≤ 30 K ~ 3.0 bar, 4.5 K Guaranteed mode of operation. Nominal turn-down condition. Forms the basis for (under safe operating point from surge) a) maximum pressure ratio 2.5-3.0 2.4-2.8 2.0-2.5 1.8-2.0 ≤ 3.8 K ≤ 31.0 mbar 1.5 HX-10R SC1R Cold Box PDR: Process Requirements

Process Requirements – Cold Compressors (contd.) Mode of Operation: Pump-down Peak 250 g/s, 1.2 bar ~ 3.0 bar, 4.5 K Transient State. Maximum mass flow rate (~250 g/s) Maximum Acceleration of CCs ≤ 6.0 K ~ 52.0 mbar HX-10R SC1R Cold Box PDR: Process Requirements

Process Requirements – Cold Compressors (contd.) Mode of Operation: Minimum Capacity 170 g/s, 1.2 bar ≤ 30 K ~ 3.0 bar, 4.5 K Expected mode of operation. Maximum turn-down mode. Helps with operation with SLINAC only ≤ 3.6 K ≤ 31.0 mbar HX-10R SC1R Cold Box PDR: Process Requirements

Process Requirements – Heat Exchanger Brazed Aluminum Plate-Fin Heat Exchanger: Stream: Primary Supply Stream Primary Return Stream [Unit] Flow Rate 250 [g/s] Operating Pressurea 2.85 (41.2) 0.0345 (0.5) [bar] Inlet Temperature 4.5 2.2 [K] Outlet Temperature 2.5 3.3 Total Duty 1.5 [kW] Corrected MTD (max.) 0.59 NTU 3 [-] Design Temperature 340/2.0 Design Pressure (max.)a 25.2 (350) 7.9 (100) Frictional Pressure Drop 1.7 2 [mbar] Inlet Header Size (max.) 4 - [NPS] Outlet Header Size (max.) Inlet Nozzle Size (max.) 10 Outlet Nozzle Size (max.) Type Connection Aluminum to Stainless steel transition joint, Slugged, Marked for Cutoff, Pressurized for Shipment a Values in the parentheses refer to the pressures in psig. SC1R Cold Box PDR: Process Requirements

Process Requirements – Heat Exchanger (contd.) Is it possible to reduce the HX capacity to meet Cold Box physical sizing constraints? Higher primary supply temperatures to LINAC. Reduced dynamic heat capacity of LINAC. Higher pressure drop (typically) in sub-atmospheric (return) side. Increases CC speeds for same flow conditions. Lower CC1 inlet temperature. Decreases CC speeds for same flow conditions. SC1R Cold Box PDR: Process Requirements

Process Requirements – Internal Piping Frictional Pressure Drop1: LINAC Pressure = ΔpRTL + ΔpHX + ΔpIP + CC1 inlet pressure 33.5 3.0 2.0 0.5 28.0 [mbar] CC5-4 CC4-3 CC3-2 CC2-1 CC1 5.5 mbar 1,0 mbar 1.8 mbar 1.2 mbar 1.0 mbar 1 at maximum flow condition with inlet conditions similar to SC2 SC1R Cold Box PDR: Process Requirements

Process Requirements – Internal Piping (contd.) Design Considerations: Minimum suction volume required to offset transients during acceleration/deceleration Parameter Value [Unit] Description FID 11   [-] Fluid ID ṁ 250 [g/s] CC Flow Rate ∆ 0.015 [mm] Absolute Roughness of SS Piping qin-leak 20 [W] Heat In-Leak (min.) CCID 1 2 3 4 5 pin 28 76 182 410 823 [mbar] Inlet Pressure (Assumed) Tin 3.6 6.2 9.7 14.7 21.2 [K] Inlet Temperature (Assumed) ρin 0.378 0.594 0.908 1.347 1.869 [g/l] Inlet Density Ṽ 661.2 420.5 275.3 185.7 133.8 [l/s] Volumetric Flow Rate τ 37.8 0.2 0.15 [sec] Time Constant (Based on SC2 Process) Vin 25 0.084 0.041 0.028 0.020 [m3] Volume Required at Inlet D 6 [in.] Piping Diameter L - 181.5 89.1 135.2 97.5 Inlet Piping Length (Required)† SC1R Cold Box PDR: Process Requirements

Process Requirements – Internal Piping (contd.) Design Considerations: Flow straighteners in inter-stage piping. Reduces vorticity at CC suction. May increase inter-stage pressure drop. Imposes restrictions on minimum piping length between stages. Per ISO 5167-1: Annex C (`Etoile Straightener) Towards CCN+1 suction From CCN discharge Fig.: Simulated vortex flow through flow straightener (left) and straight pipe (right) Fig.: Bellows – straight tube assembly SC1R Cold Box PDR: Process Requirements

Proposed P&I Paths Primary Return – CC Discharge: SC1R Cold Box PDR: Process Requirements

Proposed P&I Paths (contd.) Primary Supply – 4KCBX to LINAC: SC1R Cold Box PDR: Process Requirements

Proposed P&I Paths (contd.) LN Shield: SC1R Cold Box PDR: Process Requirements

Proposed P&I Paths (contd.) Purge / Clean-up / Warm-up: SC1R Cold Box PDR: Process Requirements

Commissioning Plan Maximum/Nominal Capacity: CHL2 (4K CBX) SC1R SC2N LERF SL NL SC1R Cold Box PDR: Process Requirements

Commissioning Plan (contd.) Minimum Capacity: CHL2 (4K CBX) CHL1 (4K CBX) SC1R SC2N SL NL LERF SC1R Cold Box PDR: Process Requirements

Summary CEBAF Cryogenic Load: 3750 W / LINAC ~ 200 g/s CC Flow CEBAF 2K Cryogenic Systems: 2x 4K Cold Box; 2x 2K Cold Box Ability to Cross-Connect Loads/Plant Process Requirements: Cold Compressors – 660 liter/sec @ 28 mbar (CC1 suction); Pressure Ratio: 42 4K-2K Heat Exchanger – 3 NTU, ~ 0.6 MTD Proposed P&I Paths: Primary Supply/Return; LN Shielding for 2K piping Purge / Clean-up / Warm-up piping Commissioning Plan (Preliminary): Commissioning with CHL2 SLinac, LERF SC1R Cold Box PDR: Process Requirements

Thank You Saturday, November 10, 2018