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Traffic Pollution: Perspective Overview toward Carbon Dioxide Capture and Separation Method
Published in Maniruzzaman A. Aziz, Khairul Anuar Kassim, Wan Azelee Wan Abu Bakar, Aminaton Marto, Syed Anuar Faua’ad Syed Muhammad, Fossil Free Fuels, 2019
Maniruzzaman A. Aziz, Khairul Anuar Kassim, Wan Azelee Wan Abu Bakar, Fauzan Mohd Jakarmi, A. B. M. Amimul Ahsan, Salmiah Jamal Mat Rosid, Susilawati Toemen
Table 10.8 shows the pros and cons of physical absorption processes using Selexol, Rectisol and Fluor [148,151]. Selexol processes are used to sweeten natural gas by removing CO2 and H2S gas in bulk. This absorption process operates at very low temperatures (between 0–5ºC). Solvents can be used for sulfur removal, CO2 and water compounds at the same time. The feed gas is dehydrated before it reaches the Selexol unit. Meanwhile, Rectisol treats hydrogen, syngas and city gas flows for impurity removal. Methanol (CH3OH) is used as a solvent in Rectisol processes due to the high-pressure vapor of methanol. Therefore, the process needs to operate at temperatures within the range of 35–75°C. The Rectisol process is for the purification of heavier components such as ethane [171]. The Rectisol process is one of the most commonly applied commercial CO2-removal processes used in the natural gas industry. Besides, the Fluor solvent process is used for treating feed gas CO2 at high partial pressures (> 60 psig). This process is based on propylene carbonate (C4H6O3), a physical solvent for removing CO2 due to its polarity and its high affinity for CO2 [172].
Feedstock Preparation
Published in James G. Speight, Handbook of Petrochemical Processes, 2019
Another absorption process, the Rectisol process, is a physical acid gas removal process using an organic solvent (typically methanol) at subzero temperatures, and characteristic of physical acid gas removal processes, it can purify synthesis gas down to 0.1 ppm total sulfur, including hydrogen sulfide (H2S) and carbonyl sulfide (COS), and carbon dioxide (CO2) in the ppm range (Mokhatab et al., 2006; Abdel-Aal et al., 2016). The process uses methanol as a wash solvent and the wash unit operates under favorable at temperatures below 0°C (32°F). To lower the temperature of the feed gas temperatures, it is cooled against the cold product streams, before entering the absorber tower. At the absorber tower, carbon dioxide and hydrogen sulfide (with carbonyl sulfide) are removed. By use of an intermediate flash, co-absorbed products such as hydrogen and carbon monoxide are recovered, thus increasing the product recovery rate. To reduce the required energy demand for the carbon dioxide compressor, the carbon dioxide product is recovered in two different pressure steps (medium pressure and lower pressure). The carbon dioxide product is essentially sulfur-free (H2S-free, COS-free) and water free. The carbon dioxide products can be used for enhanced oil recovery (EOR) and/or sequestration or as pure carbon dioxide for other processes.
Biomass gasification for bioenergy
Published in Chris Saffron, Achieving carbon negative bioenergy systems from plant materials, 2020
Maria Puig-Arnavat, Tobias Pape Thomsen, Zsuzsa Sárossy, Rasmus Østergaard Gadsbøll, Lasse Røngaard Clausen, Jesper Ahrenfeldt
significant amounts of sulphur. The most used gas cleaning method is the commercial Rectisol process (Gatti et al., 2014; Sun and Smith, 2013). It is a convenient method as it utilizes pressurized cooled methanol (around -40°C) as a solvent for a range of impurities including CO2, H2S, COS, HCl and NH3. The primary downsides of Rectisol are that it is mostly applicable to large-scale plants and that it requires a refrigeration plant consuming electricity. Other commercial gas cleaning processes for sulphur and/or CO2 include Selexol and Purisol (Kapetaki et al., 2015; Vitasari et al., 2011).
Acid gas removal techniques for syngas, natural gas, and biogas clean up – a review
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Aeman Qayyum, Usman Ali, Naveed Ramzan
Physical absorption process is the most economical and efficient process when it operates at elevated pressure and lower temperature and is preferred over chemical solvents when the concentration of acid gases or other impurities is very high in the gas stream to be treated. In addition, physical solvents can easily be stripped out of the contaminants by reduction of the pressure with little or no heat addition (Sreedhar et al. 2017), (Olajire 2010) as given in Appendix C, Table C-9. Physical solvents such as n-methyl-2-pyrrolidone (Purisol), dimethyl ether of polyethylene glycol (Selexol), propylene carbonate (Fluor) and methanol (Rectisol) are emerging as popular solvents for acid gas treatment (Burr and Lyddon 1998) as indicated in Appendix C, Table C-10. Rectisol wash is used for H2S, COS and CO2 removal simultaneously, as well as other impurities, such as HCN and NH3 can also be removed (Weiss 1988). Further, Purisol can be applied for H2S removal while CO2 remains in the treated gas (Fischer et al. 2002). Furthermore, Selexol is mainly utilized where deep H2S and CO2 removal is not required. However, Fluor process is preferably used for CO2 removal with little or no H2S present (Bucklin and Schendel 1984).