Tokamak-15 Modernization and an Analysis of Cryogenic System Operation for the Period from 1988 to 1994

Abstract

The T-15 cryogenics system has been designed for cooling down, cryostatting, warming up of superconducting, cryoresistive and cryogenics T-15 objects. Maintenance of the cryogenics system has been on going since 1988.

For the mentioned period, in the cryogenics T-15 system

• The capacity of screw compressor was increased from 0.181 kg/s to 0.236 kg/s (third stage compressors with increased capacity were developed and manufactured), their reliability was also enhanced.

• The capacity of liquefiers was increased from 0.0833 – 0.0972 L/s (300–350 L/h) to 0.222 L/s (800 L/h) due to replacement of turboexpanders by more effective ones and due to introduction of an end-stage turboexpander into maintenance.

• The heat influxes to the cryogenics pipelines were reduced by 50%.

  For the same period some technological regimes of cryogenics system have been developed to produce the maximal output of cold.

The cooling down from 110 K to 15 K is done, when one or two liquefiers are in operation under refrigerating conditions with the reverse flow splitting.

The further cooling is performed under joint operation of two liquefiers; one them operates in the liquefying mode, another, in the refrigerating one with excess reverse flow. A change in the operating conditions was necessary because of the impossibility of regulating the distribution of the reverse helium flow between two liquefiers at the temperature below 15K.

The main regime at the level of 4,5 K is a two-loop operating diagram, when one Liquefier and a passive refrigerator with excessive reverse flow are in operation, the refrigerating capacity is about 3 kW.