Reliable measurement of near-critical adsorption by gravimetric method

Abstract

A gravimetric apparatus is used to measure the excess adsorption at high pressure. The equipment consists of a Rubotherm magnetic suspension balance, which allows to measure also the density of the fluid. In order to obtain the excess adsorbed amount, the measured weight has to be corrected with a buoyancy term, for which the density of the adsorbing fluid has to be known at each experimental conditions. Therefore the homogeneity of density in the high-pressure cell plays a fundamental role in determining the accuracy of the measured excess adsorbed amounts. This paper is intended to show the impact of the actual approach to thermostating the unit on the density distribution of the adsorbing fluid inside the high-pressure cell. Namely, by changing the inlet position of the heating fluid, large differences in the measured excess adsorption are produced. The closer to the critical point of the fluid, the R. Pini, S. Ottiger . A. Rajendran . M. Mazzotti ( ) ETH Zurich, Institute of Process Engineering,

Geological models of gas in place of the Longmaxi shale in Southeast Chongqing, South China

“…For all samples, the experimental temperature was 60 C. Five extra temperature points (40,80,100,120, and 150 C) were measured for Sample 8 to construct the relationship between adsorbed gas capacity and burial depth. The detailed experimental procedures for the magnetic suspension balance equipment have been well documented in previous publications (Giovanni et al, 2001;Ottiger et al, 2008;Pini et al, 2006Pini et al, , 2010Gasparik et al, 2014b).…”

Improved manometric setup for the accurate determination of supercritical carbon dioxide sorption

“…Figure 2 shows the two determined CO 2 excess sorption isotherms on F400 of this work and the literature data near 318 K on other F400s. 6,11,20 Experimental data of this work is shown in Table III.…”

“…Additional measurements are thus important. Several researchers ͑e.g., Humayun and Tomasko 11 and Pini et al 6 ͒ have expressed their concern with respect to the accuracy of supercritical CO 2 sorption determinations. The accuracy of the gravimetric method for supercritical CO 2 sorption has recently been discussed by Pini et al 6 The focus of the present article is the accuracy of the manometric method.…”

“…Several researchers ͑e.g., Humayun and Tomasko 11 and Pini et al 6 ͒ have expressed their concern with respect to the accuracy of supercritical CO 2 sorption determinations. The accuracy of the gravimetric method for supercritical CO 2 sorption has recently been discussed by Pini et al 6 The focus of the present article is the accuracy of the manometric method. The accuracy of the manometric method far below [22][23][24][25][26][27] and far above [28][29][30][31] the critical point has been discussed in the literature.…”

“…A comprehensive overview on CO 2 storage in underground coal combined with the production of CH 4 is given by White et al 1 Experimental data of near supercritical CO 2 sorption on any type of material are scarce. A limited number of gravimetric, [2][3][4][5][6][7][8][9][10][11][12][13] manometric, 4,[14][15][16][17][18][19] and volumetric 20,21 studies have been published. Additional measurements are thus important.…”