Techniques for transformation of biogas to biomethane
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Cites background or methods from "Techniques for transformation of bi..."
...However, in cases that the biogas contains high concentrations of H2S, steam or inert gas are used in the desorption process to avoid formation of elemental sulphur by the application of air stripping, which will in turn lead to operational problems (Ryckebosch et al., 2011)....
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...clogging) derived from either the increased concentration of solid CO2 or presence of rest impurities limit the wider establishment of this technique (Bauer et al., 2013a; Muñoz et al., 2015; Ryckebosch et al., 2011)....
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...The raw biogas can be upgraded up to 96–98% methane concentration; however, up to 4% methane can be lost within the off-gas stream (Table 1) (Bauer et al., 2013a; Ryckebosch et al., 2011)....
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...The separation is carried out by initially drying and compressing the raw biogas up to 80 bars followed by a stepwise temperature drop up to −110 °C (Ryckebosch et al., 2011)....
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...The absorption column is usually filled with random packing material to increase the gas-liquid mass transfer (Ryckebosch et al., 2011)....
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Cites background or methods from "Techniques for transformation of bi..."
...These solvents allow for a decrease in both the absorbent recycling rates and 188 plant sizing, with the subsequent decrease in investment and operating costs (Petersson and 189 Wellinger, 2009; Ryckebosch et al, 2011)....
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...The oxidation of H2S and further regeneration of this adsorbent 699 material can be stoichiometrically described as follows (equations 6,7,8): 700 701 Fe2O3 + 3H2S Fe2S3 + 3H2O (6) 702 2Fe(OH)3 + 3H2S Fe2S3 + 6H2O (7) 703 31 2Fe2S3 + 3O2 2Fe2O3 + 6S (8) 704 705 These chemical reagents are often immobilized onto wood chips or red mud (a waste from 706 aluminum manufacture) in order to increase the superficial area of the adsorbent, which 707 significantly decreases as a result of aggregation due to biogas water condensation (Persson 708 et al, 2006)....
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...CH4 concentrations of 96–98 % are guaranteed by most membrane manufacturers in gas–liquid or multiple-stage gas–gas units, while single-pass gas–gas units provide a biomethane with CH4 concentrations of 92–94 % and off-gas permeates with CH4 concentrations of 10–25 % that need to be further treated (Ryckebosch et al. 2011; Andriani et al. 2014)....
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...activated alumina, zeolite and polymeric sorbents (Patterson et al. 2011; Ryckebosch et al. 2011)....
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...Lower dewpoints down to -18 ºC require the compression of 1025 the biomethane prior to cooling (Ryckebosch et al, 2011)....
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449 citations
Cites background or methods from "Techniques for transformation of bi..."
...Therefore, Selexol (mixture of dimethyl ethers of polyethylene glycol), which exhibits higher affinity for H2S than water by five times can be used, resulting in smaller absorbent volume with compact size and require regeneration step [7]....
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...In the gas–liquid separation, alkaline liquid is used on the microporous hydrophobic membrane, which can support H2S removal by 98% during desulphurization, leaving only 2% in the upgraded gas [7, 21, 22]....
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...This last one is harmful to the environment and corrosive to the metallic parts of engines, pumps, compressors, gas storage tanks, valves and reduce the lifespan of process equipment [7, 8]....
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...Although some reports [7, 8, 16, 20] reported methane losses up to 4% due to CH4 dissolution in alkanolamine....
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...Membrane is based on different molecules of different sizes with different permeability through the membrane, and is also driven by pressure difference between the two sides of the membrane and the biogas temperature [7]....
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References
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