Performance determination of high-purity N 2 -PSA-plants
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Performance determination of high‑purity N2‑PSA‑plants A. Marcinek1 · J. Guderian1 · D. Bathen2 Received: 10 September 2019 / Revised: 18 November 2019 / Accepted: 24 January 2020 © The Author(s) 2020
Abstract The global demand on highly purified gases provided by energy-efficient separation processes grows steadily since decades. An example of particular industrial relevance is nitrogen generated by pressure swing adsorption from compressed air. A kinetically based separation of oxygen from nitrogen is possible by means of carbon molecular sieves (CMS) since oxygen adsorbs remarkably faster in CMS than nitrogen. Even high product purities (5–1000 ppm O2) are easily achievable in commercial generators. However, only a few studies present experimental findings in this purity range. That comes as no surprise, since experimental conditions are not standardised and the determination of N2-PSA performance indicators still creates an experimental challenge. Moreover, the design of the set-up remarkably influences the experimental results. Thus it is the motivation of this study to develop a multi-step strategy, comprising the definition of a reference process, the derivation of explicit and implicit performance indicators based on either flow meter readings or macroscopic material balances, a verification strategy for experimentally obtained data, and an error consideration, which advices accuracy requirements for analysers and flow meters. The effect of cycle time and operating temperature on the performance indicators is exemplarily studied at high purities by means of the proposed strategy. Keywords Nitrogen generation · Pressure swing adsorption · Performance indicators · Carbon molecular sieve · Process intensification Abbreviations C Gas concentration (mol/m3) GMB General mass balance mCMS Mass of CMS adsorbent per adsorber (kg) OMB Oxygen mass balance Q Volumetric flow rate (Nm3/h) t Time (s) tcycle Cycle time (s) VCMS Volume of CMS adsorbent in adsorbers (m3) w Mass fraction (mass%) X Number of adsorbers X Arithmetic average y Molar fraction (mol.%)
* J. Guderian guderian@fh‑muenster.de 1
Department of Chemical Engineering, Muenster University of Applied Sciences, Stegerwaldstrasse 39, 48565 Steinfurt, Germany
Department of Thermal Process Engineering, University of Duisburg-Essen, Forsthausweg 2, 47057 Duisburg, Germany
2
δexp Experimental relative error of performance indicators (%) δsim Simulated relative error of performance indicators (%) ρ Gas density (kg/Nm3) σ Standard deviation σX Uncertainty in the mean value
1 Introduction Pressure swing adsorption (PSA) is a well-established technology applied for the separation of multicomponent gas mixtures. Currently a huge focus is set on CO2 capture technologies (Salazar Duarte et al. 2017; Schell et al. 2013; Ritter 2015). Nevertheless, PSA is also a well-known and frequently implemented method in traditional industrial processes such as hydrogen purification, biogas upgrading, or air separation (Dąbrowski 2001; Voss 2005;
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