Speakers
Description
This project features a tumultuous low pressure (5psi) liquid nitrogen delivery system feeding an NMR instrumentation lab via a two-phase buffer pot, exhibiting a stability analogous to a spinning top. Currently, the system requires frequent valve adjustment to maintain a stable pressure range; where without input, the two-phase buffer pot reaches a chaotic state of constant filling and venting to maintain a downstream pressure gradient of 5psi. The primary objective is to present the systems tuning parameters for LN2 delivery, which centers upon a two-phase buffer pot, investigating the source of instability and the means to increase efficiency and balance. The system is located on the roof above an NMR instrumentation lab, utilizing a vacuum jacketed (VJ) LN2 feed line entering a two-phase supply tank, with fluid volume regulated via a pneumatically operated controller fill valve, where 5psi output flows from the bottom of the tank via VJ line down and into the NMR building. The two-phase tank is equipped with a pressure relief valve set to 22psi. Overhead gas volume is maintained with an outlet vent to atmosphere, regulated with a pressure regulator valve set to 7psi and a solenoid valve set to 14psi. Ineffectual post modifications involved increasing overhead gas volume with installation of a gas phase buffer pot above the two-phase tank, connected upstream from the original pressure regulator (7psi) and solenoid valves (14psi). This project investigates the behavior of this two-phase system in flux, examining the current isothermal pressure/volume behavior, and potential improvement through design simplification.
