Tritium Fuel Cycle System
Modeling with ASPEN
-ISS and FCU
Haibo Liu
Fusion Science and Technology Center, UCLA
Scott Willms
Los Alamos National Lab
FNST/PFC/MASCO Meeting at UCLA
August 2-6, 2010
Objective
 Residence time based linear differential equation model to calculate
the tritium inventory and required TBR in fusion reactor had been
studied by Prof. Abdou and other researchers.
 To get a new model for FNSF or the future reactor required TBR
evaluation with commercial chemical engineering software.
In this presentation, the TSTA scale Isotope Separation System (ISS)
modeling will be introduced and some of the dynamic characteristics are
shown. The Fuel Cleanup Unit (FCU) is also modeled.
Non Built-in Hydrogen Molecules Definition
• Modeling of HD, HT, DT, T2 in Aspen+:
Four of the hydrogen molecules are missing from A+, which have to be defined
by user.
The Molecular Weight, Boiling Point, Critical Temperature, Critical
Pressure, Critical Volume, Triple Point Temperature, Liquid Molar Volume,
Heat of Fusion, and vapor pressure formula are Given (from Hydrogen
Properties for Fusion Energy by P. Clark Souers). But the ASPEN doesn’t know
that there are two atoms in these molecules, and so the chemical reaction rates
calculation has to be done with the known kinetics.
ISS Flowsheet for Steady-State
heater
heater
heater
heater
reactor
reactor
The Isotope Separation System (ISS) has been modeled in A+ for steady state simulation. The
design parameters are referred from TSTA.
This system has four distillation columns and two reactors. The four product (HD, D2, DT, T2) purities
are optimized in steady-state running mode.
Steady-State Input
Feed Stream: 50% DT + 25%T2 + 24%D2 + 1% H2
Extra Feed Stream: 80% D2 + 10% H2 + 5% HD + 5% HT
Feed Temperature: 20K
Feed Pressure: 1 atm
Feed Flow Rate: 2mol/min
Chemical reactor operation Temperature: 25oC
Products: H2&HD, D2, DT, T2
Blocks: 4 Columns, 2 Reactors, 4 Heaters, 2 Mixers
Column 1: reflux ratio (25), distillate rate (0.5mol/min), number of stages (80), feed stage (50), column packed height (4.11m), column I.D.
(29mm), drum&sump (H:34cm, D: 6cm, 15% liquid volume fraction), pressure (condenser: 0.9atm, stage pressure drop: 0.002atm)
Column 2: reflux ratio (150), distillate rate (0.3mol/min), number of stages (80), feed stage (55), column packed height (4.06m), column I.D.
(19mm), drum&sump (H:34cm, D:4cm, 15% liquid volume fraction), pressure (condenser: 0.7atm, stage pressure drop: 0.003atm)
Column 3: reflux ratio (8), distillate rate (1mol/min), number of stages (65), feed stage (30), column packed height (3.20m), column I.D.
(23.2mm), drum&sump (H:34cm, D:4cm, 15% liquid volume fraction), pressure (condenser: 1.04atm, stage pressure drop: 0.0007atm)
Column 4: reflux ratio (8), distillate rate (1.75mol/min), number of stages (80), feed stage (40), column packed height (4.11m), column I.D.
(38mm), drum&sump (H:34cm, D:8cm, 15% liquid volume fraction), pressure (condenser: 0.8atm, stage pressure drop: 0.003atm)
Product Stream Results
ISS Dynamics
ISS Dynamics
Stream ID
Stream ID
HD
D2
T emperature
K
19.9
T emperature
K
22.9
Pressure
atm
0.70
Pressure
atm
0.80
Vapor Frac
0.000
Vapor Frac
0.000
Mole Flow
kmol/hr
0.018
Mole Flow
kmol/hr
0.105
Mass Flow
kg/hr
0.044
Mass Flow
kg/hr
0.422
Volume Flow
l/min
0.008
Volume Flow
l/min
0.043
Ent halpy
MMBtu/hr
Ent halpy
MMBtu/hr
Mole Flow
kmol/hr
Mole Flow
kmol/hr
> -0.001
-0.001
H2
0.011
H2
trace
D2
trace
D2
0.102
T2
trace
T2
trace
HD
0.006
HD
0.002
HT
0.001
HT
0.001
DT
trace
DT
< 0.001
Mole Frac
Mole Frac
H2
0.600
H2
trace
D2
110 PP B
D2
0.973
T2
trace
T2
trace
HD
0.358
HD
0.016
HT
0.042
HT
0.007
DT
trace
DT
0.005
Stream HD
Stream D2
Product Stream Results (continue)
ISS Dynamics
Stream ID
ISS Dynamics
DT
Stream ID
T2
T emperature
K
24.5
T emperature
K
26.4
Pressure
atm
1.04
Pressure
atm
1.08
Vapor Frac
0.000
Vapor Frac
0.000
Mole Flow
kmol/hr
0.063
Mole Flow
kmol/hr
0.030
Mass Flow
kg/hr
0.317
Mass Flow
kg/hr
0.181
Volume Flow
l/min
0.025
Volume Flow
l/min
0.012
Ent halpy
MMBtu/hr
Ent halpy
MMBtu/hr
Mole Flow
kmol/hr
Mole Flow
kmol/hr
-0.001
> -0.001
H2
trace
H2
D2
< 0.001
D2
trace
T2
trace
T2
0.030
HD
trace
HD
HT
trace
HT
DT
0.063
DT
trace
Mole Frac
Mole Frac
H2
trace
H2
D2
0.003
D2
trace
T2
4 PP M
T2
1.000
HD
trace
HD
HT
trace
HT
DT
0.997
DT
Stream DT
9 PP M
Stream T2
Comparison for Column I SteadyState Composition Profile
SS Component Profile in C1
The stage is counted from the top in APD.
the stage is counted from bottom
Dimosthenis, Sarigiannis, Ph.D Thesis, UCB 1994.
ISS Flowsheet for Dynamics
The dynamic simulation has to be performed for getting the tritium inventory.
Lots of controls have to be given to the system before dynamic running, including pressure
control, temperature control, product purity control, etc.
Dynamic Response after Feed Flow Rate Ramp Increase
Components Purities
DT
D2
0~0.5Hour Feed Flow Rate: 2mol/min
FEED-D-T
STREAMS("HD").Zn("H2") kmol/kmol
STREAMS("HD").Zn("HD") kmol/kmol
STREAMS("D2").Zn("D2") kmol/kmol
STREAMS("DT").Zn("DT") kmol/kmol
STREAMS("T2").Zn("T2") kmol/kmol
0.6
0.7
0.8
0.9
STREAMS("FEED-D-T").F kmol/hr
STREAMS("NB-D2").F kmol/hr
STREAMS("HD").F kmol/hr
STREAMS("D2").F kmol/hr
STREAMS("DT").F kmol/hr
STREAMS("T2").F kmol/hr
0.1
0.12
0.14
0.16
0.18
0.2
1.0
0.22
0.24
1.1
0.26
Feed and Products Flow Rate
0.5~2.5Hour Feed Flow Rate: 2mol/min to 4mol/min
D2
0.5~2.5Hour Feed Flow Rate: 2mol/min to 4mol/min
H2
0.08
NB-D2
0~0.5Hour Feed Flow Rate: 2mol/min
T2
0.04
0.4
DT
0.02
0.0
0.5
0.06
T2
HD
HD
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Time Hours
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
9.5
10.0
0.16
0~0.5Hour Feed Flow Rate: 2mol/min
Inventory_C1_Total kmol
Inventory_C2_Total kmol
Inventory_C3_Total kmol
Inventory_C4_Total kmol
Inventory_Total_Tritium kmol
0.08
0.1
0.12
0.14
0.5~2.5Hour Ramp Feed Flow Rate from: 2mol/min to 4mol/min
0.06
C4
0.04
0.02
C1
C2
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Time Hours
5.5
6.0
Tritium Inventory
6.5
7.0
7.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Time Hours
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
9.5
In Steady-state,
Total tritium inventory in ISS: ~ 260gT
Tritium processing time in ISS: ~ 80 min
0.18
0.2
Tritium Inventory evolution for C1/C2/C3/C4/Total after Feed Flow Rate Change
C3
0.0
0.5
Component Purities
Feed & Product Flow Rates
Total in ISS
0.0
8.0
8.5
9.0
9.5
10.0
Between 1.36~1.45 hour, the T2 purity is decreased
from 99% to 95% under the ramp increase of the D-T
feed flow rate. The feed flow rate is about 0.17kmol/h
at that time interval.
This column design could not keep the T2 purity
under the feed flow rate higher than 0.16kmol/h and
the columns have to be re-optimized to stand this
increase.
10.0
Column Startup Simulation
Startup operating sequence:
1) Purge with inert gas (this is done by the
Empty script);
2) Charge the specified amount of feed
into the column sump and then stop feed;
3) Increase reboiler temperature and
buildup the drum holdup till specified level
and then start the column reflux;
The control has to be given to the
system to realize the startup operating
sequence.
This startup sequence can be changed
according to the existed experiment,
like TSTA or the ITER/FNSF design
later.
4) Continue increase reboiler temperature
5) Add some more feed until sump level
reaches specified value and stop the feed;
6) Increase the reflux rate to the final value;
7) Start the column feed to final steady-state.
Startup Tritium Inventory Buildup and He&Products flow rate
Helium & Products Flow Rate
0.0
0.0
0.00:
0.02
Inventory_Total_Tritium kmol
0.03
0.04
STREAMS("HE").Fm kg/hr
STREAMS("HE").Fmcn("HE") kg/hr
STREAMS("CD1-DIST").Fm kg/hr
STREAMS("CD1-DIST").Fmcn("HE") kg/hr
STREAMS("CD1BCD3F").Fm kg/hr
STREAMS("CD1BCD3F").Fmcn("HE") kg/hr
0.25
0.5
0.75
1.0
0.05
1.25
0.06
Column I Startup Tritium Inventory
5.0
10.0
15.0
Time Hours
20.0
25.0
Tritium Inventory Buildup during Startup/ kmol
30.0
0.0
1.0
2.0
3.0
4.0
Time Hours
Purge Gas and products Flow Rate/ kg/hr
5.0
Temperature and Pressure Profile in Column
1.4
Column Pressure Profile
1.25
/bar
Pressure /bar
Pressure
-249.5
1.05
-249.25
1.1
-249.0
1.15
1.2
Temperature oC
T_Profile C Time: 300.000000
-248.75
-248.5
-248.25
-248.0
1.3
-247.75
-247.5
1.35
-247.25
Column Temperature Profile
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
Index
45.0
50.0
55.0
60.0
65.0
Column Temperature Profile
70.0
75.0
80.0
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
50.0
55.0
Index
Column Pressure Profile
60.0
65.0
70.0
75.0
80.0
FCU Dynamics Flowsheet
Purification
Recovery
An Aspen Custom Modeler (ACM) user defined permeator has been modeled with
instantaneous assumption.
Because lack of the reaction kinetics factors, the dynamics for this sub-system has
not been finished. But this sub-system will have relative small tritium inventory, so
the dynamics simulation will be simplified.
Summary
The ISS is simulated for steady-state and dynamics operation modes.
Four absent hydrogen molecules are modeled in A+. The dynamic
response of the system from feed change is studied.
The rough tritium inventory and processing time are obtained for ISS
after this simulation.
Also the one column startup simulation is performed. The time and
the amount of the tritium inventory buildup in the system during the
startup should be considered for how it will affect the required TBR
model.
After the tritium inventories and total processing time are obtained,
the reactor required TBR model will be updated with these chemical
engineering based calculation results.
Future work
1) Startup and pulsed operation simulation will be performed for the
four column ISS and the whole fuel cycle system.
2) The storage + fueling + plasma chamber + cryopump + FCU + ISS
loop will be first evaluated for this loop’s total tritium processing time.
With the sub-system’s tritium inventory results together, the required
TBR model would be updated.
3) The tritium decay effect has to be included in the later model.
4) The user-defined hydrogen molecules should be reviewed.
5) The property method used here is “Ideal”. Which existed method
should be used in the calculation and what’s the effect on the results
should be evaluated.
Thank you for your attention!