Contactless Weighing Up to High Pressures For Analysing Adsorption And Density of Fluids

Abstract

Adsorption of supercritical fluids methane, nitrogen and argon by active carbons was studied up to a pressure of 500 bar. A three-parameter isothermal equation was used to represent the adsorption equilibrium. This isothermal equation is based on a physical model conception which had already been used for the modelling of adsorption processes with a pressure up to 150 bar. Beside the exact knowledge of the measurable parameters pressure, temperature and fluid composition, the density of the adsorbate are essential for the evaluation of the adsorption analysis. The fluid density can be determined either via equations of state, which is normally the most practicable and fastest way, or via lift measurements of a lowering body in the fluid based on the principle of Archimedes. This work represents and discusses the question of to what extent the fluid density determined under real conditions via equations of state, using, for example, equation of Bender, corresponds to the fluid density measured under high-pressure.