Experiences in the commissioning of new helium liquefier at VECC and the respective remedial actions

A new liquefier of 415 W refrigeration capacity at 4.5K has been installed at VECC along with a new compressor of 50 g/s flow rate. It has been interfaced with the existing liquefier and cryogenic loads. During commissioning of this liquefier the following problems have been faced: (i) Space constraints for installation (ii) Flanged section of pipelines at the interfacing point of the cold box and the compressor (iii) Cleaning of pipelines to ensure that no metal chips are present (iv) Testing of each and every components, of the cold box and compressor (v) Failure of a number of components and their replacement (vi) Failure to meet refrigeration and liquefaction capacity (vii) Parallel run of two compressors (viii) Shutdown of cold box for every trip of compressors (ix) LP and HP control to reduce the pressure fluctuation (x) Attenuation of the turbo-expanders (xi) Cool down of the cold box along with the cryostat (xii) Sub-cooler liquid helium level control (xiii) LP isolation of the two ORSs In this paper the measures taken for rectification of the above problems are discussed with results.