Bashir, Fidal; Mahgerefteh, Haroun; Porter, Richard; Catalanotti, Elena; (2023) Performance Analysis of Pressure Swing Adsorption Process for Carbon-Containing Off-Gas Separation in the Steel Industry. In: Proceedings of the 16th Greenhouse Gas Control Technologies Conference (GHGT-16) 23-24 Oct 2022. (pp. pp. 1-12). SSRN: Amsterdam, The Netherlands.

Preview

Text SSRN-id4272332.pdf - Other Download (1MB) | Preview

Abstract

According to the World Steel Association the iron and steel sector represents the largest energy-consuming industrial sector globally, contributing around 6% of total anthropogenic emissions, with average emissions of approximately 1.83 tonnes CO2 per tonne of steel. The gases produced in the steelmaking process are generated in different parts of the plant and display different characteristics. The three main streams of off-gases produced during the process: Blast Furnace Gas (BFG), Coke Oven Gas (COG) and Basic Oxygen Furnace Gas (BOFG) have similar constituents, being made up of CO, CO2, H2, N2 and CH4 and are usually used as fuels internally in different process units within the plant . The CO2 and N2 rich BFG stream is the most significant with a flow rate about 20 times larger than the other two available streams and thus represents a significant target for CO2 capture. These streams contain the right ingredients for valorisation by thermochemical conversion to fuels or commodity chemicals, but they may require prior conditioning or separation to make overall processes economically viable. In recent years, many methods have been developed to recover and capture valuable gases from industrial off-gases for utilisation or storage, thereby minimising the adverse impacts of global warming by reducing overall emissions. As one of the above methods, Pressure Swing Adsorption (PSA) provides an efficient and mature technology for the recovery of gases from multicomponent streams such as steel off-gases. PSA is a cyclic adsorption process that allows continuous gas stream separation. PSA is performed by periodically alternating the pressure from low to high and is considered viable for separating desired components from off-gases. A PSA system essentially consists of two or more adsorption towers filled with absorbent materials, filters, and a storage reservoir. In addition, gas compressors and vacuum pumps are also employed to dynamically alter the system pressures by means of a switching valve assembly. Despite its importance, the details of the performance of the PSA process at conditions relevant to those encountered in the iron and steel industry has received little attention in the scientific literature. In light of the above, this work aims to model the implementation of PSA to recover CO2 from BFG, CO from BOFG and H2 from COG. Three independent PSA systems are modelled using Aspen Adsorption, with each system fitted with different adsorbents, specific designs and configurations for the desired outlet gas. These involve layered beds packed with activated carbon and zeolite 5A, and two separate Vacuum Pressure Swing Adsorption (VPSA) towers. All three PSAs were modelled as Skarstrom cycles. The layered bed PSA recovers H2 from a 40,000 Nm3/h stream of COG (CO 6%, CO2 2%, H2 65%, N2 4%, CH4 23%), achieving 99 vol% purity >90% recovery. VPSA was employed to analyse CO recovery from 35,000 Nm3/h BOFG (CO 58%, CO2 20%, H2 5%, N2 18%) at a 1.2 bar and ambient temperature using a Cucl/AC adsorbent to achieve a 98vol% and purity >90% recovery. The simulation and optimisation studies for CO2 recovery from 730,000 Nm3/h BFG (CO 20%,CO2 24%, H2 3%, N2 53%) employing a commercial Zeolite 13X as the adsorbent to achieve >98% purity CO2. Breakthrough validation was performed by comparing the simulation results with experimental data. Figure 1 shows the validation for H2 recovery from COG, which was validated against work from literature. Furthermore, a parametric study was carried out to determine the purity of PSA systems for gas separation from different steelworks off-gases.

Download activity - last month

Export as CSVXMLJSON

Download activity - last 12 months

Export as JSONCSVXML

Downloads by country - last 12 months

Export as CSVXMLJSON

Archive Staff Only

View Item