Abstract
The pressure swing adsorption (PSA) process was used to capture carbon dioxide (CO2) from the flue gas of a coal-fired power plant to reduce CO2 emissions. Herein, CO2 was captured from flue gas using the PSA process for at least 85 vol% CO2 purity and with the other exit stream from the process of more than 90 vol% N2 purity. The extended Langmuir–Freundlich isotherm was used for calculating the equilibrium adsorption capacity, and the linear driving force model was used to describe the gas adsorption kinetics. We compared the results of breakthrough curves obtained through experiments and simulations to verify the accuracy of the mass transfer coefficient. The flue gas obtained after desulphurization and water removal (13.5 vol% CO2 and 86.5 vol% N2) from a subcritical 1-kW coal-fired power plant served as the feed for the designed three-bed, nine-step PSA process. To determine optimal operating conditions for the process, the central composite design (CCD) was used. After CCD analysis, optimal operating conditions with a feed pressure of 3.66 atm and a vacuum pressure of 0.05 atm were obtained to produce a bottom product with a CO2 purity of 89.20 vol% and a recovery of 88.20%, and a top product with a N2 purity of 98.49 vol% and a recovery of 93.56%. The mechanical energy consumption was estimated to be 1.17 GJ/t-CO2.
Highlights
This study is an improved version of the previously published work [1]
In the precombustion capture method, CO2 is captured before combustion, which separates CO2 from the synthesis gas produced from coal gasification in an integrated gasification combined cycle (IGCC) power plant
The first stage involved a three-bed five-step process, and the second-stage involved a two-bed six-step process. Both stages used zeolite 13X-APG as the adsorbent, and the results indicated that a CO2 purity of 96.54 vol% was obtained, with a recovery of 93.35%, energy consumption of 528.39 kJ/kgCO2, and productivity of 8.61 × 10−6 kg CO2/kg s
Summary
This study is an improved version of the previously published work [1]. Driven by higher energy demand in 2018, global energy-related CO2 emissions rose 1.7% to a historic high of 33.1 Gt CO2 [2]. The first stage involved a three-bed five-step process, and the second-stage involved a two-bed six-step process Both stages used zeolite 13X-APG as the adsorbent, and the results indicated that a CO2 purity of 96.54 vol% was obtained, with a recovery of 93.35%, energy consumption of 528.39 kJ/kgCO2, and productivity of 8.61 × 10−6 kg CO2/kg s. Alibolandi et al [30] used zeolite 13X and carbon molecular sieve as adsorbents in a four-bed eight-step PSA process to separate 80 vol% nitrogen and 20 vol% CO2, showing that the performance of zeolite 13X was better than that of the carbon molecular sieve They achieved optimal results involving a CO2 purity of 97.6 vol% in a cycle time of 560 s and an adsorption pressure of 3.66 atm. A PSA process was developed to capture CO2 from a subcritical 1-kW coal-fired power plant in the Taiwan Power Company and the developed PSA process is operating at the Taichung Power Plant
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