Title: Performance of the Prototype Gas Recirculation System with built-in RGA for INO RPC system M.Bhuyana, V.M.Datarb, Avinash Joshic, S.D.Kalmania*, N.K.Mondala, B.Satyanarayanaa and P.Vermaa
1Performance of the Prototype Gas Recirculation
System with built-in RGA for INO RPC
systemM.Bhuyana, V.M.Datarb, Avinash Joshic,
S.D.Kalmania, N.K.Mondala,B.Satyanarayanaa and
P.Vermaa
- Department of High Energy Physics, Tata Institute
of Fundamental Research, Mumbai 400005, INDIA - Nuclear Physics Division, Bhabha Atomic Research
Centre, - Mumbai 400085, INDIA
- c) Alpha Pneumatics, 11-Krishna Kutir, Madanlal
Dhingra Road, - Thane 400602, INDIA
2Plan of talk
- Gas Recovery System
- Open Loop System (Fractional Condensation
Method) - Preliminary results
- Tool for analysing gas
- RGA (Residual Gas Analyser)
- Some results
- Closed Loop system
- Some results
- Conclusion
-
-
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4Properties of Gases
PARAMETER UNIT R134a (C2H2F4) ISOBUTANE (C4H10) ARGON (Ar) SULPHUR HEXA FLUORIDE(SF6)
MOL. WT gm/mole 102.3 58.12 39.948 146.05
STRUCTURE RING RING ------ RING
GAS DENSITY Kg/M3 4.25 2.82 1.78 6.27
LIQUID DENSITY Kg/M3 1206 593 1400 1880
VISCOSITY cP 0.012 0.006 0.02 0.015
BOILING Pt. C -26.3 -11.7 -185.8 TRIPLE PT -49.4, 2.2BAR SUB. PT -63.9
HEAT OF VAPOURIZATION KJ/MOL 22.021 23.300 6.43 23.681
CRITICAL TEMP. C 101.1 134.9 -122.13 45.5
CRITICAL PRESSURE BAR A 40.6 36.84 48.98 37.59
GLOBAL WARMING POTENTIAL CO21 4200 ----- ----- 22400
PURITY LEVEL USED 99.8 99.9 99.999 99.9
IMPURITIES O2,H2O N3,CF4 CH4,H2, H2O,N2 N2,O2,H2O,HC H2O,O2,CF4
5STAGES OF RECOVERY PROCESS BY OPEN LOOP PROCESS
- Cleaning and purification of gas mixture
returning from RPCs. - Separation of condensable gases by selective
adsorption on catalyst surface (activated
palladium) - Successive Recovery of gases by fractional
condensation at decreasing temperatures.
6CATALYSTS AND ADSORBENTS
- MOLECULAR SIEVES TRAP GAS MOLECULES OF
PARTICULAR SIZE - Soduim Potasuim Calcium Aluminum
Silicate are used in different proportion to
formulate the following sieves - TYPE 3A
TO TRAP MOISTURE 23 w/w -Maximum - TYPE 4A
TO TRAP ARGON Absence of moisture - TYPE
5A TO TRAP n BUTANE - TYPE
13X TO TRAP OIL VAPOURS - Activated Aluminum( to
remove radicals F-,HF etc.) - CATALYST ACTIVATED ALUMINA
PALLADIUM TO PROMOTE -
CONDENSATION OF ISOBUTANE (Adsorption surface200
Sq.mtr /gm) -
ACTIVATED CARBON TO ADSORB ISOBUTANE - ZIRCONIA
BASED ZEOLITES (ZSM) TO PROMOTE -
ISOBUTANE n BUTANE CONVERSIONS - SILICA GEL Wide Range of pore size, good for
water adsorption (Chemically bonds Water)
7PARTIAL PRESSURE TEMPERATURE RELATIONSHIP OF
VAPOUR-LIQUID SYSTEM CLAUSIUS CLAPEYRON
EQUATION FOR BOILING POINT
WHERE TB BOILING
POINT, K R IDEAL
GAS CONSTANT, 8.314 J/K-mol
P0 VAPOUR PRESSURE OF GAS AT GIVEN
TEMPERATURE, KPa
ABS. ?HVvap HEAT OF
VAPOURIZATION, J/mol T0
GAS TEMPERATURE
8Liquid phase
Gas Phase
Liquid Phase
Gas Phase
Note While Conversion of Gas to Liquid Heat is
released by which other gas molecules temperature
goes up and efficiency of condensation goes down
so cu-plates, cu-collecting jars are used in the
condensation unit.
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11RGA Vacuum Analysis Mass Spectrometer
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13RGA Operation
14PEFIER VACUUM
Benchtop Station with high pumping speed
Ultimate pressure lt 10-8 mbar
DCU allows control and diagnostics of pumping station
Pumping Speed N260L/s
Dry and Oil-Free!
TMH/U 071
MVP 015-2
DCU 001
Turbo-Drag Pumping Station
15Fine Tune Needle Valve
16RGA Experimental Set-up
17Example RGA Library
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19Comparison of R134a (Domestic and Imported
(Praxair))
20R134a R134a
33 100
69 37.84
83 21.22
31 12.48
51 9.17
30 4.86
68 4.58
63 4.58
32 3.44
i-C4H10 i-C4H10
43 100
41 50.68
42 49.77
27 31.32
39 17.70
40 12.66
26 11.15
29 6.64
15 5.19
SF6 SF6
127 100
89 27
108 9
51 8
54 7
70 5
32 5
35 5
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22m Fragment
33 CH2F 100
69 CF3 32
83 C2H2F3 15
51 CHF2 9
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2583 C2H2F3 51 CHF2 32 CHF 69
CF3 43 C2F 20 HF etc
C2H2F4?CF3 CH2F (one of peak in Isobutane)
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30Conclusion
- During recovery process the gas mixture is cooled
down to -18o C . If moisture content of the gases
is more than 50 ppm ( Dew point higher than -18o
C), a thin layer of ice will form on Palladium
catalyst surface. As a result catalyst is
temporarily deactivated and separation stops .
recovery process gradually comes to a halt
resulting in strong cross contamination between
Isobutene and R134a . - Molecular sieve column has been put to take care
of small quantity of moisture , but ingress of
air adds large amounts of moisture that can not
be handled by Desiccation column. - The first sign of this problem appears as rise of
condensation pressure. The machine has to be
defrosted and dried complete for few hours
during which the recovery is not effective. -
31Conclusion
- We have also developed a Residual Gas Analyser
(RGA) based system to monitor the purity of input
gases and their mixing ratio as well to identify
the contaminants in the return gas. - The gas going to the RPC and that coming out of
RPC which has contaminated radicals ?? - Major problem of Air leak entering into
Recovery system /Closed need to be addresed ,
before doing further tests.
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