Impianto Criogenico di ALPI

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1 Impianto Criogenico di ALPI INFN Laboratori Nazionali di Legnaro 1

2 Impianto Criogenico di ALPI 2

3 Medio β 160 MHz Nb/Cu (ex Pb/Cu) Alto β 160 MHz Nb/Cu. CR12 CR13 CR14 CR15CR16 CR17 CR18 CR19 CR20 B4 B3 Liquefattore/Refr. CR10 CR9 CR8 CR7 CR6 CR5 CR4 CR3 B2 ALPI Basso β 80 MHz Nb XTU TANDEM P I A V E EXPERIMENTAL HALLS 1, 32

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6 Le componenti fondamentali Compressori di Ciclo e Buffer Compressori di recupero e stoccaggi Essiccatore Purificatore di Macchina Refrigeratore/Liquefattore Scambiatore di calore He/N 2 (Cold Box Ausiliaria) Linee criogeniche Sistema da Vuoto Criostati Sistema di controllo di produzione (EUROTHERM PC3000) Sistema di controlo per la Distribuzione di elio liquido/gas Alstom(ex Marconi) 6

7 Compressori di Ciclo (Settembre 2002) Con l installazione del nuovo sistema di compressione (2 compressori) tre differenti combinazioni di flusso G-He saranno possibili e il massimo flusso sarà limitato a 190 g/s dal Liquefattore A B C 65 g/s 95 g/s 110 g/s A+B 160 g/s B+C 205 g/s A+C 175 g/s Limitato a 190 g/s dal Liquefattore 7

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10 Compressori di Recupero e Stoccaggi 2 Compressori da 150 m 3 /h Schultzer (asserviti a ALPI e PIAVE) Prelevano il gas da un gasometro (pallone da 100 m 3 ) e lo comprimono verso gli (8+8, 6400 Nm 3 totali) siluri a 200 atm (siluri ALPI e AURIGA) 10

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12 Essiccatori 2 essiccatori (Cirrus) da 70 Nm 3 /h 1,5 ppm di H 2 O Hanno inoltre la funzione di ridurre la pressione da 200 a 30 atm 12

13 Compressori di Recupero e Stoccaggi 2 Compressori da 150 m 3 /h Schultzer (ALPI e PIAVE) 13

14 Linee Criogeniche Mandata e Ritorno per G-He (gas) K verso gli schermi dei criostati Mandata e Ritorno del L-He (liquido) verso i serbatoi dei criostati Tubi super-isolati in vuoto di 10-5 mbar 14

15 Liquefattore/Refrigeratore Ciclo Claudet Scambiatori 180 K, 60 K, 14 K 2 turbine in cascata in controflusso Circuito con valvola Joule-Thomson espansore a pistoni per aumento di potenza (Wet Expander) Potenza nominale 3900 a 77 K e 1300 a 4.5 K Dewar di Stoccaggio 2000 litri 15

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17 Scambiatore di calore He/N 2 (Cold Box Ausiliaria) Ha la scopo di entrare funzione in situazioni di emergenza per mantenere freddi (60 K) gli schermi dei criostati 2 circolatori per forzare la circolazione di He-gas litri di N 2 Autonomia di 4 giorni 17

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21 Main Troubles in the ALPI sub-systems Cryogenic System: anomalous compressor deterioration (8000 hr instead of the foreseen 30000) failure in the internal purifier (Spring 2000, safety valve modified), not enough RAM in the control system (now upgraded from 64k to 256k) Wet Expander not enough reliable (under test) Difficulty in transferring steadily L-He in low energy ALPI branch (redesign of few valve box: On/Off Proportional Valves) 21

22 He Cycle Compressors in April 2000 a shut down was scheduled in order to substitute the two He cycle compressors A and B A ( working hours); OK B (8 000 working hours) with decreasing working pressure preventing a reliable functioning of the ALPI cryogenic plant The two dismounted cycle compressors were checked by MYCOM Europe in September 2000 and the aperture at the end of the II stage was modified in order to reduce the oil pressure. A tender for the acquisition of a new compressor (110 g/s) was defined in the year The Installation is foreseen for the summer

23 Cryogenic Control System The Wet Expander was installed in September 1999 and tested in manual mode in October The up-grading of the Cryogenic Control System has been done in December 1999 new PLC (PC3000 EUROTHERM) new operating system increased RAM (64 kb=>128/256 kb) new diagnostics added to better control the processes 23

24 Cryogenic Plant Failure At the end of the successful runs of February and March 2000, just before the shut down procedure of the cold box, we had a serious failure in the Cold Box itself a non-controlled OVER-PRESSURE in the internal He purifier opened the top flange of the purifier. the internal purifier was dismounted and sent to AIR LIQUIDE for repairing in April 2000 back from AIR LIQUIDE at the end of June 2000 re-installed on the Cold Box by AIR LIQUIDE in mid July 2000 the Cold Box was closed at the end of July and ready for the cold down at the beginning of September

25 Cryogenic Plant improvements Two additional safety valves have been introduced to prevent over-pressure problems on the internal purifier a capacitive probe has been added on the LN 2 bottle of the internal purifier to check the LN 2 level a new WEKA valve and a new by pass (johnston type) has been added on the internal purifier to allow the future implementation of an external purifier two immersed valves have been substituted with WEKA external actuators modification of the cold box top flange (removable flange with the insertion for the new capacitive probe) 25

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