Presentation on theme: "Performance of the Prototype Gas Recirculation System with built-in RGA for INO RPC system M.Bhuyan a, V.M.Datar b, Avinash Joshi c, S.D.Kalmani a *, N.K.Mondal."— Presentation transcript:
Performance of the Prototype Gas Recirculation System with built-in RGA for INO RPC system M.Bhuyan a, V.M.Datar b, Avinash Joshi c, S.D.Kalmani a *, N.K.Mondal a, B.Satyanarayana a and P.Verma a a)Department of High Energy Physics, Tata Institute of Fundamental Research, Mumbai , INDIA b)Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai , INDIA c) Alpha Pneumatics, 11-Krishna Kutir, Madanlal Dhingra Road, Thane , INDIA
Plan of talk oGas Recovery System : Open Loop System (Fractional Condensation Method) Preliminary results oTool for analysing gas RGA (Residual Gas Analyser): Some results oClosed Loop system : Some results oConclusion
Properties of Gases PARAMETERUNITR134a (C 2 H 2 F 4 ) ISOBUTANE (C 4 H 10 ) ARGON (Ar) SULPHUR HEXA FLUORIDE(SF 6 ) MOL. WTgm/mole STRUCTURERING RING GAS DENSITYKg/M LIQUID DENSITYKg/M VISCOSITYcP BOILING Pt.°C TRIPLE PT: -49.4, 2.2BAR SUB. PT: HEAT OF VAPOURIZATION KJ/MOL CRITICAL TEMP.°C CRITICAL PRESSUREBAR A GLOBAL WARMING POTENTIAL CO 2 = PURITY LEVEL USED% IMPURITIESO 2, H 2 O N 3,CF 4 CH 4,H 2, H 2 O,N 2 N 2,O 2,H 2 O,H C H 2 O,O 2,CF 4
STAGES 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.
CATALYSTS 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 surface~200 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)
PARTIAL PRESSURE – TEMPERATURE RELATIONSHIP OF VAPOUR-LIQUID SYSTEM CLAUSIUS –CLAPEYRON EQUATION FOR BOILING POINT WHERE: T B : BOILING POINT, °K R : IDEAL GAS CONSTANT, J/°K-mol P 0 : VAPOUR PRESSURE OF GAS AT GIVEN TEMPERATURE, KPa ABS. ΔH Vvap : HEAT OF VAPOURIZATION, J/mol T 0 : GAS TEMPERATURE
Liquid 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.
RGA :Vacuum Analysis Mass Spectrometer Stanford Research Systems Dual Thoriated-Iridium Filament RS-232c Interface
PEFIER VACUUM Benchtop Station with high pumping speed Ultimate pressure < mbar DCU allows control and diagnostics of pumping station Pumping Speed N2=60L/s Dry and Oil-Free! DCU 001 TMH/U 071 MVP Turbo-Drag Pumping Station
Fine Tune Needle Valve Controls the fine flow of Gas in the RGA operating range [1.2 X10 -5 to 8.2 X10 -5 ]mbar Input flow Out flow Fine tune
RGA Experimental Set-up
Example :RGA Library
Comparison of R134a (Domestic and Imported (Praxair))
R134a i-C 4 H SF
m Fragment % 33 CH2F CF C2H2F CHF2 9
83 = C 2 H 2 F 3 51 = CHF2 32 = CHF 69 = CF3 43 = C2F 20 = HF etc C2H2F4 CF3 +CH2F (one of peak in Isobutane)
Conclusion During recovery process the gas mixture is cooled down to -18 o C. If moisture content of the gases is more than 50 ppm ( Dew point higher than -18 o 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.
Conclusion 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.