Transcript How to recover tritium from LiPb and helium; EU experience with gas liquid contactor

Tritium extraction from Pb16Li
and He: EU experience and proposals
I. Ricapito, ENEA CR Brasimone, FPN-FISING
Fusione, Tecnologie e Presidio Nucleare
Sezione Ingegneria Sperimentale
IEA Workshop on T/Pb16Li
Idaho Falls, 11-12/06/2007
OBJECTIVE
To summarise the EU experience on tritium extraction from Pb16Li and
He for DEMO and Power Plant, presenting at the same time the
proposals to ITER for TBM tritium processing systems. Moreover possible
fields of collaboration are indicated.
OUTLINE
 Tritium extraction from Pb-16Li
 Tritium extraction from He (TRPS; CPS)
 Proposals for EU TBMs T-systems
 TES/TRPS
 CPS
 Possible developments
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IEA Workshop on T/Pb16Li
Idaho Falls, 11-12/06/2007
Tritium Extraction from Pb-16Li
Different technologies have been
proposed and studied in EU
spray columns
 GAS LIQUID CONTACTORS
 V GETTERS
plate columns
bubble columns
packed columns
 BUBBLE COLUMN-PERMEATOR (SiC-SiCf)
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IEA Workshop on T/Pb16Li
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Tritium Extraction from Pb-16Li
Most of the experimental activities on GL contactors were
carried out on Melodie loop
MELODIE LOOP: PFD
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IEA Workshop on T/Pb16Li
Idaho Falls, 11-12/06/2007
Tritium Extraction from Pb-16Li
Results from Melodie loop on GL contactors
Bubble columns: experimental results on Melodie loop
800 mm height, 54 mm diameter, 673 K
Test n.
LM flow-rate Ar flow-rate
PH2, in
(%)
(lh-1)
(N lh-1)
(Pa)
1
80 -105
30
1300 -1400
10 -12
2
80 -105
60
1200
9 -11
3
50 - 65
60
1150 -1200
>14
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IEA Workshop on T/Pb16Li
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Tritium Extraction from Pb-16Li
Results from Melodie loop on GL contactors
Packed columns: experimental results on Melodie loop
800 mm height, 54 mm diameter, packing area: 750 m2/m3, T:673 K
Test n.
(%)
LM flow-rate
Ar flow-rate
PH2,in
(lh-1)
(N lh-1)
(Pa)
10
70-90
6
1200-1350
20-22
11
30-50
6
1000-1100
29-31
12
30-50
30
975-1000
29-31
13
30-50
6
450-475
23-25
14
30-50
6
220-230
23-25
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IEA Workshop on T/Pb16Li
Idaho Falls, 11-12/06/2007
Tritium Extraction from Pb16Li
G-L contactors, experimental results: summary
 disappointing results were obtained by bubble columns because of the
small G-L interface area: particularly, coalescence of gas bubble, already
at low gas flow-rate, was claimed to be the main reason of the low
efficiency
 maximum extraction efficiency was nearly 0.3, achieved with packed
columns (0.8 m in height)
 the effect of hydrogen addition to the purge gas on the extraction
efficiency was not studied
 L/G molar ratio was not optimised
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IEA Workshop on T/Pb16Li
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Tritium Extraction from Pb16Li
TES: V Getters
 V was selected because of the high Sieverts’ constant for tritium
and good compatibility with Pb-16Li
 A deuterium gettering rate constant in the range 10-7 10-8 mol m-2
s-1 mbar-1/2 was experimentally determined, increasing with the
temperature because of the increasing deuterium diffusivity in the
LM boundary layer (controlling step in the mass transfer)
 the system is more compact than G-L contactors for a given
extraction efficiency
 a cyclic operation is intrinsically necessary (two beds in parallel)
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IEA Workshop on T/Pb16Li
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Tritium Extraction from Pb16Li
TES: bubble column- permeator
Pb-16Li inlet
He +Q2
tritium is recovered by two channels in parallel:
He
- a tritium flow from LM to ascending bubbles
- tritium permeation through 2D- SiCf/SiC with a sweep He
flow recovering permeated Q2 or by vacuum
He +Q2
Pb-16Li outlet
High extraction efficiency is claimed to be achievable with a very
compact system, but experimental confirmation is necessary
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IEA Workshop on T/Pb16Li
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Tritium Extraction from Pb16Li
Ongoing activities on TRIEX loop at ENEA CR Brasimone
Aims:
- study and optimisation of GL contactors
(first phase)
- study and optimisation of alternative
technologies (integrated bubble columnpermeator) in the ambit of international
collaboration
column operative temperature:
623-723 K;
internal diameter of the column:
12.8 cm;
column height:
20-120 cm
specific surface of the filler:
350 m2/m3
mass flow rate of Pb-16Li:
G  0.2-1.0 kg/s;
Segmented packed column
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IEA Workshop on T/Pb16Li
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Tritium Extraction from He purge (TRPS)
SG
H2
P
TES
CPS
Pb-16Li
Q2
HCS
H2O, H2
ISS
to fuelling
He+Q2+ imp.
Q2
TRPS
He
impurities
Q2
WGS
 TRPS is the process downstream a GL based TES
to stack
 TRPS feed stream depends on the GL contactor design specification
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IEA Workshop on T/Pb16Li
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Tritium Extraction from He purge (TRPS)
Tritium Removal from Purge Gas: TRPS
Candidate Processes
 VPSA (Vacuum Pressure Swing Adsorption)
 TSA (Thermal Swing Adsorption)
 PdAg Permeator battery
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IEA Workshop on T/Pb16Li
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Tritium Extraction from He purge (TRPS)
VPSA process
Adsorption column
He+Q2
VP
V1
V2
V5
Q2 to ISS
V3
H2
V4
V6
To Imp.
Processing
pure He to TES
Process steps
a)
Feed pressurisation (all valves closed except V1)
b)
Adsorption at 77 K and 1-2 MPa (all valves closed except V1, V3)
c)
Co-current blow-down (all valves closed except V2, V4)
d)
H2 addition (all valves closed except V6)
e)
Co-current evacuation (all valves closed except V2, V5)
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IEA Workshop on T/Pb16Li
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Tritium Extraction from He purge (TRPS)
TSA process
Alternative to VPSA is a cryogenic TSA process. For this application TSA is
operated at 77 K in adsorption phase, while the regeneration of the adsorbent
beds takes place under counter-current He stream at RT or under vacuum,
depending on the bed dimensions.
Recovered Q2, concentrated in the He regeneration stream, is then processed by
Q2 permeators (Pd-Ag)
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IEA Workshop on T/Pb16Li
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Tritium Extraction from He purge (TRPS)
Pd-Ag Permeators (solution proposed for DEMO)
Blanket
Permeator 5
Permeator 4
Permeator 3
Permeator 2
Permeator 1
Blanket
Vacuum
Pump
O2 addition
Vacuum
Pump
Vacuum
Pump
Vacuum
Pump
to HISS
Cooler
O2 recirculator
Water to WGSR
In the last reactor-permeator HT partial pressure in the shell side is virtually
zero by oxygen addition
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IEA Workshop on T/Pb16Li
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Tritium Extraction from He purge (TRPS)
Considerations on TRPS
 TSA is more technologically mature than VPSA, especially when operated at
cryogenic temperature, because of the simplicity of the regeneration phase
 in TSA tritium inventory is higher than in VPSA: in VPSA configuration, the
adsorbent beds are much more compact than in TSA
 Pd-Ag permeators require large surface area and pumping power because of
the low differential Q2 partial pressure (driving force)
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IEA Workshop on T/Pb16Li
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Tritium Extraction from He purge (CPS)
About CPS…
CPS is the most critical tritium system in HCLL blanket
(DEMO or Power Plant) because of:
- large feed flow-rate to be processed: in the worst
conditions (PRF=1, low LM flow-rate) it exceeds 10 % of
the total coolant flow-rate, which is unacceptable
- relatively small Q2 concentration in the feed stream
- presence of Q2O and impurities at very low partial
pressure (range of Pa)
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IEA Workshop on T/Pb16Li
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Tritium Extraction from He purge (CPS)
Possible Working Points
LM flow-rate (kg/s)
800
1600
1600
PRF
10
10
10
TES efficiency
80%
80%
60%
CPS efficiency
95%
95%
90%
T_perm. rate (g/d)
12.3
4.8
9.0
Average T conc. in LM (mol m-3)
2.3x10-2
1.2x10-2
1.8x10-2
CPS feed flow-rate (Nm3/h)
2.1x106
8.2x105
1.6x106
Fraction of the coolant flow-rate
2.7%
1.1%
2.1%
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IEA Workshop on T/Pb16Li
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Tritium Extraction from He purge (CPS)
CPS:
possible configuration
(possibly to be tested in ITER)
for
DEMO/Power
Plant
He + Q2 + Q2O + imp.
H2O + H2
IN
OUT
oxidizer (Cu2O-CuO)
RHE
700-750 K
CT
He
Q2O
ADSORBERS
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2
impurities to WGDS
IEA Workshop on T/Pb16Li
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Proposals for EU TBMs T-systems
General Statements
 Each TBM will have a Tritium Extraction System (TES) to extract
the small amount of tritium generated
 Each TBM will have a Coolant Purification System (CPS) for the
extraction of tritium permeated into coolant
 Processing
of
tritium
within
the
Tritium
Plant
could be carried out, alternatively, through:
the Tokamak Exhaust Processing System
with the subsequent tritium recovery by the Isotope Separation
System
or the Vent Detritiation System
with subsequent tritium removal / recovery by Water Detritiation
System and, in series, Isotope Separation System
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IEA Workshop on T/Pb16Li
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Proposals for EU TBMs T-systems
Integration of TES/CPS in the ITER Fuel Cycle
He purge gas
TES
to SDS
TRPS
TBM
Q2
TEP
ISS
HCS
CPS
A/VDS
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WDS
IEA Workshop on T/Pb16Li
Idaho Falls, 11-12/06/2007
Proposals for EU TBMs T-systems
In view of ITER
For the EU TBMs (HCLL and HCPB), the tritium extraction from
He purge could be accomplished by two diferent systems for the
low duty and high duty DT phase, respectively
Low duty: isolated pulses, low amount of Q2 to be extracted
High duty:
sequence of standard pulses (back to back pulse series)
or long pulses
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Proposals for EU TBMs T-systems
TES in the low-duty DT phase (isolated standard
pulses)
 For the low duty DT phase, a simple “Tritium Measurement
System” (TMS) could be used as TES.
TMS
(FZK concept)
 is based on a Zn reducing reactor, followed by a U getter bed
 it has to be equipped by suitable tritium accounting system (on line
or in the tritium building)
 has to be placed close to the TBM (port cell)
 requires a space approximately 2.3x1.3x1.5 m (LxWxH) for both
HCPB and HCLL TBMs
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Proposals for EU TBMs T-systems
EU TBMs: gas stream to be processed by TES/TRPS
HCPB-TBM
HCLL-TBM
TRS-HCLL: inlet gas properties
TES-HCPB: properties
Feed flow-rate (Nm3/h)
8
Feed flow-rate (Nm3/h)
0.23
Temperature (K)
723
Temperature (K)
673
Pressure (Pa)
1000
Pressure (Pa)
1000
HT molar fraction (vppm)
3.9
HT molar fraction (vppm)
21
H2 molar fraction (vppm)
1070
H2 molar fraction (vppm)
1000
HTO molar fraction (vppm)
0.13
HTO molar fraction (vppm)
-
H2O molar fraction (vppm)
3.9
H2O molar fraction (vppm)
-
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Proposals for EU TBMs T-systems
TES/TRPS
For the high duty DT phase (back to back pulse series and long pulses), different
alternatives could be envisaged. One of them is here proposed which is, in principle:
- able to recover Q2 with a good efficiency (90%) and in a wide range;
- able to distinguish between HTO and HT generated in the breeder;
- DEMO relevant
A candidate process consists, essentially, of two in series TSA systems, the
first one operated at RT in adsorption phase for Q2O removal and the second
one at LN2 temperature for Q2 removal.
In this process the main components are:
- a cooler to cool down the He stream from the TBM outlet (450°C) up to RT
- a TSA for Q2O removal operated at RT in adsorption phase (for HCPB-TBM)
- a pre-cooler to cool down the dry He stream close to LN2 temperature
- a TSA for Q2 removal operated at LN temperature in adsorption phase
- a heater to bring the pure He stream to RT
- a blower to circulate the He stream into HCPB-TBM
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Proposals for EU TBMs T-systems
TES/TRPS
Properties of the Q2O-TSA and Q2-TSA
parameter
Q2O TSA
Q2 TSA
Temperature in adsorption phase
298
78
Total mass flow-rate (g/s)
0.4 (8 Nm3/h)
0.4 (Nm3/h)
Duration of adsorption phase (FPh)*
36
6
Temperature in regeneration phase (K)
573, He purge
RT, vacuum
Duration of heating + regeneration phase (h)
6
6
He flow-rate for regeneration (Nl/h)
150
-
Column length (cm)
50
60
Column internal diameter (cm)
20
20
Adsorbent material (pellet 1/16”)
Silica-gel
Zeolite 5 A
- n. 7 ionization chambers, located in different
points of the circuit. Their measurement range
is 1E3÷1E6 Bq/ml
- n. 3 H2 detectors, with a range of 1E-3÷1E0
% in He
- n. 2 hygrometers, located in the regeneration
loop of Q2O-TSA; measurement range -60÷+10
°C (d.p.)
-n. 1 gas-chromatograph, with a measurement
Max tritium inventory in HTO form (Ci)
45 (31 mg)
-
range of the impurities as 1E-1÷1E2 vppm
Max Q2O inventory (g) in Q2O-TSA
0.92
-
Mean Q2O molar fraction in regenerating He (%)
0.12
-
Max tritium inventory in HT form (Ci)
-
225 (31 mg)
Max Q2 inventory (g)
-
4.6
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Analytical instrumentation consists of:
IEA Workshop on T/Pb16Li
Idaho Falls, 11-12/06/2007
Proposals for EU TBMs T-systems
EU TBMs: gas stream to be processed by CPS
CPS-HCLL: INLET GAS
CPS-HCPB: INLET GAS
3
3
Feed flow-rate (Nm /h)
7.0
Feed flow-rate (Nm /h)
42
Temperature (K)
773
Temperature (K)
773
Pressure (MPa)
8
Pressure (MPa)
8
H2 partial pressure in the feed stream (Pa)
H2O partial pressure in the feed stream (Pa)
T molar fraction, HT-HTO (vppm)
Impurities (CO2, N2, CQ4, O2)
1000
30
3.7e-2
10
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H2 partial pressure in the feed stream (Pa)
H2O partial pressure in the feed stream (Pa)
T molar fraction, HT-HTO (vppm)
Impurities (CO2, N2, CQ4, O2)
1000
30
3.7e-2
10
IEA Workshop on T/Pb16Li
Idaho Falls, 11-12/06/2007
Proposals for EU TBMs T-systems
CPS /1
The proposed CPS for HCPB-TBM is a three stage process, derived from
the DEMO conceptual design:
1) oxidation of Q2 and to Q2O and CO to CO2 by means of an oxidising
reactor (Cu2O-CuO) operated at 280 °C;
2) removal of Q2O by a room temperature PTSA (Pressure Temperature
Swing Adsorption);
3) removal of the impurities by a cryogenic PTSA
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Proposals for EU TBMs T-systems
CPS /2
parameter
Q2O-PTSA
IMP-PTSA
Temperature in adsorption phase
298
78
Mass flow-rate in adsorption phase (g/s)
0.35 (7.0 Nm3/h)
0.09 (1.75 Nm3/h)
Pressure in adsorption phase (MPa)
8
8
Duration of adsorption phase (h)
3
3
Temperature in regeneration phase (K)
573
373
Flow-rate in regeneration phase (Nl/h)
90
50
Pressure in regeneration phase (MPa)
0.2
0.2
Duration of heating + regeneration phase (h)
3
3
Column length (cm)
110
50
Internal Column diameter (cm)
17
15
Adsorbent material (pellets, 1/16”)
Silica-gel
Zeolite 13X
Max tritium inventory in HTO form (Ci)
1.0 (0.7 mg)
-
Max Q2O inventory (g) in Q2O-TSA
2.2
-
Mean Q2O molar fraction in regenerating He (%)
0.12
-
Analytical instrumentation
consists
of:
- n. 4 ionization chambers, operated in
the range 1E2÷1E4 Bq/ml
- n. 3 hygrometers, with a measure
range -80÷0 °C (d.p.)
n.
1
gas-chromatograph
with
detectable range of impurities 1E1÷1E2 vppm
Size: 4.5x1.8x2.8 m (LxWxH)
close to HCS compressor (TWCS vault)
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Possible developments /1
Tritium Extraction from PbLi
 Although many experiments were done in the past years on Melodie
loop at CEA, experimental and modelling activities on the optimisation
of tritium extraction systems from LLE need to be continued.
 An extensive experimental campaign is foreseen in TRIEX loop on GL
contactors, particularly for packed columns, with the aim to optimise
them with respect to different operating parameters: G/L, H2 content in
the stripping gas, hydrodynamics.
TRIEX loop is available to test other tritium extraction technologies for
their study and optimisation (e.g.: permeators and coupled bubble
columns/permeator)
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Possible developments /2
Tritium Extraction from He
 Technologies of tritium extraction from He have been identified for
both tritium extraction from the purge gas (TRPS) and coolant
purification systems (CPS) but no related experimental campaigns have
been carried out so far.
 Adsorption technologies are potentially
applications but experiments on lab scale
attractive
for
such
 adsorption multicomponent equilibria on different microporous materials under relevant
pressure, temperature and gas composition;
 adsorption kinetics
and on pilot plants appear necessary taking into account the demanding
performance and the very unusual feed stream properties.
 Modelling of the system is the next step activity, useful also to refine
the sizing of TES/TRPS and CPS for ITER
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IEA Workshop on T/Pb16Li
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