A new empirical scaling equation for accurate prediction of gaseous species equilibrium adsorption on activated carbon

Abstract

Adsorption models have many applications in industry such as in gas separation and/purification, natural gas storage, and CO 2 capture. In this work, a simple and robust method is introduced for calculation of natural gas and biogas adsorption on activated carbon, which is not only less complex than existing models but also not limited to isothermal condition. The proposed equation collapses the experimental data at different temperatures into a single linear curve, from which the adsorbed amounts at equilibrium can be calculated for any desired pressure and temperature in the range of experimental data. Model parameters are also calculated and presented for different gas components on activated carbon, and the accuracy of the proposed model is compared with that of three most common adsorption isotherms. As a result, the proposed scaling equation approach is shown to be more accurate and robust than the Langmuir and Sips models. Also, although application of these models is limited to isothermal condition, the proposed model is temperature dependent. It is shown that the proposed model predicts the experimental data with less than 4% error in term of sum of squared errors, and with correlation factors (R 2 ) higher than 0.95, which demonstrate the applicability of the developed approach. Proposed scaling equation scheme could help adsorption-based process design and separation or purification of mainly CH 4 from natural gas and/or biogas streams with distinct CO 2 -based contents along with a decrease in necessity of experimental data to address these purposes. KEYWORDS activated carbon, adsorption, adsorption isotherm, biogasNomenclature: A 1 , proposed model constants (g/g adsorbent/bar); A 2 , proposed model constants (g/g adsorbent); ANG, adsorbed natural gas; b, b 0 , Sips/Toth models constants (1/bar); CNG, compressed natural gas; CSS, CO 2 capture and sequestration; K L , Langmuir model constant (1/bar); LNG, liquefied natural gas; N, number of data; n, n 0 , Sips model constants; NG, natural gas; n P , proposed model constant, pressure exponent; n T , proposed model constant, pseudoreduced temperature exponent; P, pressure (bar); q eq , equilibrium adsorption per unit mass of adsorbent (g/g adsorbent); q m , Langmuir model constant, maximum uptake capacity of gas at the adsorbent surface (g/g); q s , Sips/Toth models constant (g/g); Q RT 0 , heat coefficient;R 2 , correlation factor; RMSE, root mean square error; SSE, sum of squared error of prediction; t, Toth model constant; T, temperature (K); T c , critical temperature (K); y i , original data value; b y i , modeled data value; y i , original data mean value; Y, X, proposed model variables Greek Letters: α, Sips/Toth model constant

Achieving the Super Gas-Wetting Alteration by Functionalized Nano-Silica for Improving Fluid Flowing Capacity in Gas Condensate Reservoirs

“…There are two important conditions for achieving super gas-wetting alteration: one is to reduce the surface free energy, and the other is to increase the surface roughness at multiple scales. In the system, when the gas-wetting solution touches the surface of the core, the gas-wetting nanoparticles are adsorbed on the core surface via electrostatic force and hydrogen bonding to form a super gas-wetting adsorption layer . Among them, the fluorocarbon chain reduces the surface free energy, whereas the nanoparticles increase surface roughness so that the core surface can be altered from liquid-wetting to super gas-wetting.…”

“…In the system, when the gas-wetting solution touches the surface of the core, the gas-wetting nanoparticles are adsorbed on the core surface via electrostatic force and hydrogen bonding to form a super gas-wetting adsorption layer. 47 Among them, the fluorocarbon chain reduces the surface free energy, whereas the nanoparticles increase surface roughness so that the core surface can be altered from liquidwetting to super gas-wetting. The schematic diagram is shown in Figure 5d.…”

Experimental and Modelling Study of Gravity Drainage in a Three-Block System

“…Two-phase flow in fractured rocks is relevant to various application, ranging from geothermal energy (Babaei and Nick 2019;Erfani et al 2019), groundwater contamination (Gleeson et al 2009;Sebben et al 2015;Aminnaji et al 2019;Aljuboori et al 2019;Dejam 2019), carbon capturing and storage (Emami-Meybodi et al 2015;Babaei and Islam 2018;Erfani Gahrooei and Joonaki 2018;Dejam and Hassanzadeh 2018;Erfani et al 2020;An et al 2020b;Ershadnia et al 2020), and soil salinization (Weisbrod and Dragila 2006) to enhanced hydrocarbon recovery (Farajzadeh et al 2012;Rokhforouz and Akhlaghi Amiri 2017;Rokhforouz and Amiri 2018;Bakhshi et al 2018;Rabbani et al 2020a;Chen et al 2020;An et al 2020a). The complexity of the fluid flow in highly heterogeneous rocks is caused by the notion that the fluid flows in two different media, matrix block and fracture, which separates the fluids into flowing and stagnant regions due to property contrast (Erfani et al 2019;Hasan et al 2019;Soltanian et al 2019;An et al 2020c;Aziz et al 2020;Rabbani et al 2020b;Hasan et al 2020).…”