High-speed density measurement for LNG and other cryogenic fluids using electrical capacitance tomography

The global custody transfer market for liquefied natural gas (LNG) has grown at a strong pace in the last decade and use of LNG as transport fuel considerable environmental benefits. quantity is traded on basis energy transferred, calculated from volume, density gross calorific value. High-speed, accurate measurement therefore significant commercial electrical capacitance tomography (ECT) device described this paper potential to measure rapidly, on-line moderate cost. Continuous monitoring variation during dynamic flow also gives good indication change fluid quality thus onset boiling which known affect accuracy. ECT leading candidate be explored online measurements through permittivity, addition average value, it offers image permittivity across whole conduit, allowing localised bubbles, or other variations identified measured. We report here experiments explore cryogenic applications. An 8-electrode test sensor was designed, built tested laboratory conditions then liquid nitrogen. resolution imaging capability are shown comparable that under conditions. reported nitrogen an analogue fluid, but results presented believed representative many fluids. Although been widely literature multiphase flows general, its not previously flows. This proof principle multi-phase measurement. Dielectric constant strongly linked density, design shows estimated relative 1.45 with standard error 0.034. Measurement stability gave rms output static better than 0.001 units even though unguarded only single electrode ring. primary errors associated nature sensor, primarily designed concept material demonstrator. In addition, such would provide clear images any give estimation concentration velocity bubbles. scope work sensor.