0428同步年報-2021-全

102 ACTIVITY REPORT 2021 of the pressure-regulating device was greatly shaken for a period of about 24 hours; the pressure fluctuation range was 2–4.2 barg, which was a large fluctuation when compared to the normal operation situation 2–2.6 barg. Because of the long-distance transfer and the random use of LN 2 , pressure fluctuations were unavoidable. The mechanical pressure-regulating device stabilized the downstream pressure fluctuations and reduced their impact on the cryogenic equipment of the beamline. The downstream pressure of the pressure-regulating device is about 1.48 to 2.1 barg. The static heat loss is an important quality indicator for the vacuum-shielded pipeline. This section describes the measurement of the heat load of this branch line. Pure saturated liquid nitrogen flowed through the LN 2 branch line. The static heat load along the entire path q T vaporized the liquid, thus delivering the gas to the keep- full device. The total rate of mass flow, m T , was measured after warming the cold gas with a passive heater. m T is the vaporized LN 2 from the static heat load as the supply of the LN 2 was interrupted during the measurement. The calculation of the heat load was based on the following equation, m T × h fg = q T in which h fg is the enthalpy of LN 2 . Fig. 6 : Pressure fluctuations of the tank, pressures upstream, and downstream of the pressure-regulating device. Fig. 7 : The exhaust gas of the keep-full device. Figure 7 shows the mass flow measurement result. The average flow rate was about 1.5 L/min. Using the equation, we obtained the total heat load to be 5.68 W. Two-phase flow, pressure fluctuations, condensation of water or ice, and noise in exhaust devices are all common problems in liquid nitrogen pipelines. The cryogenic team considered and eliminated these issues when designing and commissioning the branch line. The pressure- regulating device eliminated the pressure-fluctuation issue. The keep-full device improved the purity of the liquid fluid in the branch line, which replaced the separator that had been installed before the beamline cryogenic equipment. Sound suppression and the temperature controller reduce noise and avoid condensation. The overall heat load of the branch line (length 6 m) is about 5.6 W at 77 K. The commissioning with the beamline DCM device also had excellent test results. The design, fabrication, and assembly by the cryogenic team in NSRRC decreased not only the budget but also time. The design of more complex cryogenic piping for TPS is currently in the works. (Reported by Huang-Hsiu Tsai) Reference 1. H. H. Tsai, F. Z. Hsiao, H. C. Li, S. H. Chang, T. F. Lin, W. S. Chiou, C. P. Liu, Phys. Procedia 67 , 183 (2015).