closed brayton cycle power for pebble bed...
TRANSCRIPT
Closed Brayton Cycle Power for Pebble Bed Reactors
Jim Kesseli, Brayton Energy, LLC
January 30, 2017
CANES
Center for Advanced Nuclear Energy Systems
* A MITEI Low – Carbon Energy Center*
77 MASSACHUSETTS AVE CAMBRIDGE MA 02139-4307
Introductory Notes and Acknowledgements
• Notes from Prof. Jacopo Buongiorno: “focus your talk on Helium Brayton, both the heat compact exchangers and the turbomachinery, with emphasis on readiness, performance, challenges, and importantly cost wrt steam cycle.”
• Acknowledgements:• Portions of this work was sponsored by X-energy (2010-2013) covering the
early studies of the direct Brayton cycles.
• PBMR Inc sponsored Brayton Energy studies 2004-2008, for the development of an alternative recuperator.
• AREVA sponsored Brayton Energy studies of IHX for indirect cycles 2005-2007
Closed Cycle Brayton for Pebble Bed Reactors
GeneratorPre
-coole
r
Turbine Compressor
Recuperator PEBBLE BED
REACTOR
Containment
AC power terminals Containment
Heat
rejection
Principles:• Gas turbine (Brayton cycle) • Working fluid: inert gas (He favored,
non-radioactive release)
Attractions:• Simplicity: “One major moving part”• No water or steam• Simplified pressure boundary for
coding
4
8-stage Axial –
Centrifugal
Compressor
Axial
turbine
(2-stage)
PM Alternator (12 MWe)
Turbomachinery for closed He cycle - high stage count for He. (Pr~3)
• Closed-cycle He working fluid
• Only one moving part
• No mechanical wear – all magnetic bearings
• Shaft speed motor/alternator, for variable power
control.
Cost ~ $500/kWe
State of Readiness: • Conservative aero
design loading • Low stress• Common low
temp alloys • High TRL • Mag bearings • PMA
~600mm diameter turbine rotor Axial compressor diameter~ 400mm, centrifugal ~800mm
10MW Helium Cycle Turbo-Alternator
Reactor inlet temp = 500ºC
Reactor outlet temp = 850ºCPeak Pressure = 4 MPa
He mass fraction = 15%,
Ar mass fraction = 85%
η-electric=0.28
η-electric=0.29
η-electric=0.30
Efficiency trades: Basic cycle ~30% thermal-electric
7
• Step 1- Brayton’s cycle model for trade studies• Step – 2: Concepts NREC Agile™ Software for refined performance
modeler, maps, and blade design for turbine and compressor
Structural ANSYS Aero
FEA
Brayton Turbomachinery Design Sequence - Readiness: Very Mature
Aerodynamic
1. Cycle studies- Pr, N, η …
2. 1-D geometry definition, based on nondimentional parameters (specific speed, head coefficient…(defines speed and rough geometry, stage count)
3. Mean-line analysis: ηc, ηt, map prediction.
4. 2-D Blade geometry generator: stream-line coordinate methods.
5. 3-D full performance analysis and refinements
8
Mechanical
1. Rotor-dynamic analysis (seals an bearings)
2. Cost analysis trade studies
3. AN2 stress / creep life: scoping studies: material selection
4. Preliminary CAD modeling – for polar characteristics for rotor dynamic analysis & bearing design.
5. Detailed FEA: Thermal structural analysis, blade dynamics
6. Final CAD – manufacturing.
Notes on turbine life• Very low TIT (750°C), blade root
temp <<700 °C• Due to low loading coefficient
(best efficiency) low stressTherefore:• No blade cooling • Solid blades (vs cored)• Generic alloys • Blisks possible if size permits 9
Alloy MAR-M 247
Current thinking: Blisk and fully machined first test articles
Modular Pebble Bed Modular Reactor for X-energy
2010-2012
Closed cycle recuperated gas turbine (He)
Almost half the cost was the alternator & bearings
Mass (kg) 10 500
108663 $10,595,296 $9,663,663
Normalized Cost $/kWe $1,060 $966
Item Mass (kg) Low Prod. Cost High Prod. Cost $/kg
RECUPERATOR 5710 $579,626 $325,149 $102
TURBOMACHINERY 7824 $1,047,357 $864,711 $134
ALTERNATOR AND POWER ELECTRONICS 30833 $4,394,597 $4,141,464 $143
HEAT REJECTION TANKS 34395 $542,642 $362,940 $16
MAIN VESSEL & SUPPORTS 29901 $274,499 $259,362 $9
SYSTEM INSTALL 0 $74,775 $42,439
COOLING TOWERS 0 $3,550,000 $3,550,000
INVENTORY CONTROL SYSTEM 0 $131,800 $117,597
CONTROLS & INSTRUMENTATION
TOTAL 108663 $10,595,296 $9,663,663
Cost at Production Level:
Mass (kg) 10 500
108663 $10,595,296 $9,663,663
Normalized Cost $/kWe $1,060 $966
Item Mass (kg) Low Prod. Cost High Prod. Cost
RECUPERATOR 5710 $579,626 $325,149
RECUPERATOR CORE 3072 $523,155 $285,923
RECUPERATOR TIE ROD 208 $8,664 $4,870
RECUPERATOR CASE 838 $9,872 $7,948
HP EXHAUST MANIFOLD 1591 $37,935 $26,409
NO. CORES 18
TURBOMACHINERY 7824 $1,047,357 $864,711
TURBINE MODULE 3144 $253,132 $190,654
COMPRESSOR MODULE 2487 $200,167 $154,912
SHAFT UNIT 73 $8,100 $6,917
BEARING ASSEMBLY 36 $514,160 $457,585
SUPPORT AND MOUNTING 2084 $30,253 $24,333
FINAL ASSEMBLY 0 $41,545 $30,311
ALTERNATOR AND POWER ELECTRONICS 30833 $4,394,597 $4,141,464
ALTERNATOR 18636 $2,040,120 $1,927,620
MOUNTING 12196 $208,247 $185,966
POWER ELECTRONICS 0.00 $2,146,230 $2,027,878
UTILITY INTERFACE $540,000 $510,222
LOAD BANK $2,160,000 $2,040,889
CABLES AND WIRING $54,000 $51,022
ENCLOSURE $54,000 $51,022
HEAT REJECTION TANKS 34395 $542,642 $362,940
PRESSURE VESSEL 7251 $66,996 $25,078
INTERNAL FIN MODULE 15449 $239,313 $170,639
EXTERNAL FIN MODULE 10784 $221,332 $155,309
INSTALLATION 912 $15,000 $11,913
MAIN VESSEL & SUPPORTS 29901 $274,499 $259,362
VESSEL 24498 $247,920 $234,249
SUPPORT STRUCTURE 5403 $26,579 $25,114
SYSTEM INSTALL 0 $74,775 $42,439
FACTORY ASSEMBLY 0 $15,845 $8,743
RIGGING & TRANSPORT 0 $14,396 $9,124
ON SITE ASSEMBLY 0 $44,534 $24,572
COOLING TOWERS 0 $3,550,000 $3,550,000
DRY COOLING TOWERS & FANS $3,400,000 $3,400,000
COOLANT PUMPS $50,000 $50,000
PLUMBING $100,000 $100,000
INVENTORY CONTROL SYSTEM 0 $131,800 $117,597
COMPRESSOR 0 $105,000 $93,685
AFTERCOOLER 0 $1,200 $1,071
CONTROLS AND PIPING 0 $25,600 $22,841
CONTROLS & INSTRUMENTATION
TOTAL 108663 $10,595,296 $9,663,663
Cost at Production Level:
Mass (kg) 10 500
108663 $10,595,296 $9,663,663
Normalized Cost $/kWe $1,060 $966
Item Mass (kg) Low Prod. Cost High Prod. Cost
RECUPERATOR 5710 $579,626 $325,149
RECUPERATOR CORE 3072 $523,155 $285,923
RECUPERATOR TIE ROD 208 $8,664 $4,870
RECUPERATOR CASE 838 $9,872 $7,948
HP EXHAUST MANIFOLD 1591 $37,935 $26,409
NO. CORES 18
TURBOMACHINERY 7824 $1,047,357 $864,711
TURBINE MODULE 3144 $253,132 $190,654
COMPRESSOR MODULE 2487 $200,167 $154,912
SHAFT UNIT 73 $8,100 $6,917
BEARING ASSEMBLY 36 $514,160 $457,585
SUPPORT AND MOUNTING 2084 $30,253 $24,333
FINAL ASSEMBLY 0 $41,545 $30,311
ALTERNATOR AND POWER ELECTRONICS 30833 $4,394,597 $4,141,464
ALTERNATOR 18636 $2,040,120 $1,927,620
MOUNTING 12196 $208,247 $185,966
POWER ELECTRONICS 0.00 $2,146,230 $2,027,878
UTILITY INTERFACE $540,000 $510,222
LOAD BANK $2,160,000 $2,040,889
CABLES AND WIRING $54,000 $51,022
ENCLOSURE $54,000 $51,022
HEAT REJECTION TANKS 34395 $542,642 $362,940
PRESSURE VESSEL 7251 $66,996 $25,078
INTERNAL FIN MODULE 15449 $239,313 $170,639
EXTERNAL FIN MODULE 10784 $221,332 $155,309
INSTALLATION 912 $15,000 $11,913
MAIN VESSEL & SUPPORTS 29901 $274,499 $259,362
VESSEL 24498 $247,920 $234,249
SUPPORT STRUCTURE 5403 $26,579 $25,114
SYSTEM INSTALL 0 $74,775 $42,439
FACTORY ASSEMBLY 0 $15,845 $8,743
RIGGING & TRANSPORT 0 $14,396 $9,124
ON SITE ASSEMBLY 0 $44,534 $24,572
COOLING TOWERS 0 $3,550,000 $3,550,000
DRY COOLING TOWERS & FANS $3,400,000 $3,400,000
COOLANT PUMPS $50,000 $50,000
PLUMBING $100,000 $100,000
INVENTORY CONTROL SYSTEM 0 $131,800 $117,597
COMPRESSOR 0 $105,000 $93,685
AFTERCOOLER 0 $1,200 $1,071
CONTROLS AND PIPING 0 $25,600 $22,841
CONTROLS & INSTRUMENTATION
TOTAL 108663 $10,595,296 $9,663,663
Cost at Production Level:
12
H2
H3
H4
H5
H1
C1
C2
C3
C4
Helium cycle
SCO2 Recompression Cycle-Top
SCO2 Cycle-Bottom
NHS boundary
IHX
-1
IHX
-2
Emer
gen
cy b
y-p
ass
cir
cuit
Butterfly valve
Start heater
HeliumCO2Water/glycol
Brayton-sCO2 Combined Cycle PCS System
Gen
com
pre
sso
r
turbine
Sole
no
idva
lve
Safe
ty b
y-p
ass
valv
e
Gen
Gen
Fan cooler
Fan cooler
• Economics highly leveraged by cycle efficiency
• Potentially 40 to 50% efficiency
• State of Readiness for sCO2 cycles: low TRL
13
H2
H3
H4
H5
H1
C1
C2
C3
C4
Helium cycle
SCO2 Recompression Cycle-Top
SCO2 Cycle-Bottom
NHS boundary
IHX
-1
IHX
-2
Emer
gen
cy b
y-p
ass
cir
cuit
Butterfly valve
Start heater
HeliumCO2Water/glycol
Brayton-sCO2-ORC Combined Cycle PCS System
Gen
com
pre
sso
r
turbine
Sole
no
idva
lve
Safe
ty b
y-p
ass
valv
e
Gen
Gen
Fan cooler
Fan cooler
• Economics highly leveraged by cycle efficiency
ORC
20%
25%
30%
35%
40%
45%
50%
55%
300 400 500 600 700 800 900
Turbine Inlet Temp, C
Effi
cien
cy
MIT papers
Aspen CaseStudy atPR=4.2
Published SCO2 Efficiency Studies
14
ASPEN Case Study
• Pressure Ratio = 4.17
• Compressor polytropic eff = 0.84
• Turbine polytropic eff = 0.88
• Alternator efficiency = 0.96
• Power Electronics (or gear )
efficiency or 0.97
• Cooling system parasitic = 0.97
• Heat Addition DP/P = 2%
• Recup HX eff = 0.90
& SNLA papers
TIP 250 bar
TOP, bar Efficiency
Split
Fraction
Pressure
Ratio
40 40.84% 0.196 6.25
45 42.39% 0.196 5.56
50 43.89% 0.196 5
55 45.29% 0.191 4.55
60 50.48% 0.326 4.17
65 49.77% 0.315 3.85
70 48.87% 0.288 3.57
75 47.96% 0.258 3.33
80 46.94% 0.206 3.13
85 46.05% 0.169 2.94
90 45.13% 0.098 2.78
95 43.62% 0.005 2.63
100 41.48% 0 2.5
Estimated cost for Combined Cycle PCUHigher vs basic direct cycle, but lowered full power plant cost
Note: Budgetary costs for sCO2 cycle based on rough engineering estimates and not substantiated by suppliers
Unit Number Mass (kg) 10 500
RECUPERATOR -
TURBOMACHINERY 9,708 $880,235 $695,130
ALTERNATOR AND POWER ELECTRONICS 8,393 $1,319,321 $1,244,995
MAIN VESSEL & SUPPORTS 11,213 $102,937 $97,261
SYSTEM INSTALL - $74,775 $42,439
COOLING TOWERS (INSTALLED) - $4,167,391 $4,167,391
INVENTORY CONTROL SYSTEM -
CONTROLS & INSTRUMENTATION -
TOTAL PCS 29,314 $6,544,660 $6,247,216
SCO2 POWER MODULE (no heat addition or rejection HXs) $16,400,000 $11,480,000
INTERMEDIATE HEAT EXCHANGERS 19,320 $1,126,384 $957,426
TOTAL PCS 48,634 $24,071,044 $18,684,643
Power, MWe 15 15
Normalized cost $/kWe 1,592,000$ 1,235,757$
Actually just over 17MW-e
16
A Joint Venture between ESKOM and British Nuclear Fuels Corp./Westinghouse Corporation
PBMR: Direct Cycle He gas-cooled nuclear reactor (2002-2007)
Brayton Energy was sponsored to develop a low cost, strain-tolerant recuperator
17
BRAYTON’s PBMR Recuperator
Shut-off Disk
BRAYTON
Energy, LLC
Factory assembled module,
Recup- welded stack
of cells
Recup cell -
brazed
HP gas interface
We have worked on every aspect of the integrated
PBMR recuperator package
Recup core
w/integral
manifolds
LP gas interface
Recup module 3x6 m
18
Brayton Recuperator PBMR highlights• Compact containment vessel diameter: 2.8 meters
• Factory install recup into Class-1 vessel • Full factory acceptance test• Vessel transport width suitable for highway truck, • Arrives at PBMR power plant needing only external connections.
• No internal support structure (“cradle”)– Recup cores supported from cool HP pipes
• Cumulative damage factor for PBMR maneuvers and full mission profile = 0.0 (infinite fatigue life) – based on 12-mo. of ANSYS analysis
• Demonstrated hermetic pressure boundary and creep resistance exceeding 30-yr life (ongoing full-scale cell tests employing Larsen-Miller time extrapolation)
• Weight: HX core – 29,000 kg (common 304 or 316 stainless)• ½ to ⅓ of Heatric core
• Manufacturing plans for GEA, in Germiston So. Africa
19
Integration and assembly
• Preliminary layout and integration
• Review of specifications vs design - TBD
20
2.8m
5.3m
This integration design requires no internal support structures, as the cores are suspended from the ring manifolds by their integral manifolds.
Annular module, 1 of 4)
PBMR Recuperator Assembly
Recup cores: 61 per row or module4 modules totaling 244 cores
High-pressure (HP) piping and toroidal ring manifolds – delivers cool HP
21
Top of assembly – co-axial HP duct per PBMR specification.
Interconnecting vertical distribution pipes connect feeder to ring manifolds (omitted for clarity)
Cores hang from ring manifold on short rigid HP pipes transitioning to the integral core manifold pipes (50 mm dia,)
Hot flex pipes tolerate differential growth and provide interface to central collector pipe
Ring manifold
HP gas inHP gas outHP gas in
22
Core to core annular seal(keeps hot LP within the annulus and the cooler LP exit on the Class-1 vessel interior surface
Large (2.2m) bellows surrounds core modules on cool side, permitting the cores to move axially with the growth of the central hop HP pipe. This AISI316 bellows was quotes at a price of $5,000.
Hot LP gas enters co-axial pipe at bottom
LP in
LP out
LP out
Class-1 pressure vessel bathed in LP out gas
23
LP Seals bridge core to core annulus.Insulation to fill between cores (omitted for clarity)
Coaxial HP duct – as specified by PBMR
HP Flex piles on hot side – 50 mm dia, 2mm wall thickness
HP –cool intake pipes support core weight
insulation
24
50 mm diameter HP flex pipes staggered.
Compensating bellows and tie bar on cool 106°C HP side).
Insulation
510 C LP gas in
25
Testing in Phase 1- Brayton addressed critical design and life issues
1. Manifold flow distribution measurement and model validation
2. Wavy fin and straight fin friction factor measurements
3. Brazed folded wire matrix pressure drop characterization vs. braze parameters
4. Rupture tests-coupons (at room temp, to qualify manufacturing processes)
5. Rupture tests – cells (at room temp)
6. Long duration creep tests at peak PBMR temps
26
A battery of test performed for PBMR recuperatorTest specimen (52 folds, 100-mesh folded screen)
Suction port
Static pressure taps
Ambient air in port
Rubber sealRubber seal
Test Section volume1100x700x150mm
Microprocessor controller and safety monitor
Gas bottles (N2)
• P = 17MPa
• P = 41.3 MPa
Pressure
control
switches
(Bread-
board)
Regenerative Blower
Manometer Bank
Flow Meter
Cell InletCell Outlet
Regenerative Blower
Manometer Bank
Flow Meter
Cell InletCell Outlet
Brazed high-density formed screen flow test Header & manifold flow distribution measurements
High-temp high-pressure cell creep
High pressure destructive tests for braze strength characterization
27
• Photo shows SN048 and
SN056 in creep test rig
• Photos taken at
approximately 600 hours
@ 17.2 MPa, 510°C
• Two additional cells (S/N
83 and 85 were later
installed at 24.2 MPa gas
pressure.
• All four cells are still
operating, each with over
2400hrs accumulated –
Brayton will maintain
experiment to 8,000 hrs
High Temp creep testing - full scale Recup cells (5 mm x 480 mm), integral manifold omitted for these tests
Cells pressurized through capillary tubes with N2
28
0
50
100
150
200
250
300
350
400
450
500
1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06
Time, HRS
MP
a
ASME Code N-47-30, Section III,
Div 1, ASME Boiler & Pressure
Vessel Code, Creep Stress
Rupture
σ_F/A for SN83, S/N85
σ_F/A for SN79, S/N83
σ_F/A for SN048, SN056
F/A fin stress for pressure allowable
PBMR spec,
30-year
Design point,
30-years
P=6MPa
σ_F/A=29 MPa
510 C
Yield,Special Metals
Four samples past 2000-hour mark in early March 07 – Test still in progress; Based on Larsen-Miller time-temp extrapolation of this data – cells will easily meet 30-year creep requirement
(17.2MPa)
(24.1 MPa gas pressure)
29
• The Larson-Miller theory of creep enables the extrapolation of metal failure data to different pressures, temperatures, and times. Applying the known theory to a sample failing at our design conditions of 262,800 hours, 510 C (783K) and 6MPa gas pressure (28 MPa fin tensile stress), enables the prediction of failures at other conditions. Since it is impractical to conduct a creep test at 6MPa, 510C and wait for 30 years to prove viability, Larson-Miller provides a means for predicting the relative pressure increase associated with shorter time intervals. Applying this theory for theses conditions is the basis for extrapolation shown on the previous slide. The reference line in red, emanating from the theoretical design point predicts shorter rupture times, at increasing pressures (or fin stress) for a comparable safety margin. A failure below this reference line indicates that the target conditions are unattainable. Operating above the reference line implies some measure of safety margin.
Explanation of creep life extrapolation
30
PBMR Recuperator cost modelProcess $/Cell
Parting sheets Materials 1.85
Parting Sheet processing 0.07
Braze materials 1.52
Braze application 1.13
Fin materials 3.47
Fin processing 1.60
Manifold Rings materials 1.01
Manifold Rings Processing 3.14
Cell Assembly 1.29
Braze processing (furnace charges) 1.59
Braze processing labor 2.09
Cell to core weld assembly 1.42
Total cell cost 20.17
Number of cells 80820
Total Factory Cost, $ 1,630,427
• Price excludes tooling, and is appropriate for second full recup order.
• Based on material prices quoted in March 2007 from ZAPP rolling mill
• Labor rates based on US rate of $75/hr
The design point for each
Recuperator (2 each)
Primary inlet temperature, C 512.5
Primary inlet pressure, kPa 2977
Primary mass flow, kg/s 101.1
Secondary inlet temperature,
C 108.5
Secondary inlet pressure, kPa 8927
Secondary mass flow, kg/s 95.54
Effectiveness 97.26%
Pressure drop (sum dp/p) 1.00%
Cycle pressure ratio 3.00
$, USD Weight , kg $/kg
Recuperator core & tooling 1,630,427 29,000 56.22
Manifolds, flex pipe, bellows 199,384 11,846 16.83
Vessel , 2.8 m x 6 m
Total, US$ 1,829,811
Power, electric, MW 120 from 400 MWthermal
Inflation 2007-2016 1.16 US labor statistics
Normalized cost, FY2016
$/kWe 17.69
Recup module, less
vessel
The Recuperator represents a small fraction of the PBMR cost
2 each required
31
A Joint Venture between ESKOM and British Nuclear Fuels
Corp./Westinghouse Corporation
Noble gas-cooled nuclear reactor
Brayton turbomachinery and heat exchangers
Cost ~ 35 $/kWe
BRAYTON performed
preliminary design of
the Intermediate Heat
Exchanger “IHX” for
AREVA/Framatome
(2005/2006)
850 C IHX• State of Readiness: High • Costs: please call