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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.
Flue gas purification from SO2 and NOx using molten mixture of alkali metal carbonates
Published in International Journal of Coal Preparation and Utilization, 2022
Nurlan Dosmukhamedov, Valery Kaplan
These reactions lead to the reduction of sulfate to carbonyl sulfide (COS) gas or to H2S gas that leaves the melt. Laboratory-scale experiments that have been conducted show that nearly complete sulfur removal from the melt is possible at 823 K and that the reaction rate is sufficiently high for a large-scale process. In addition, we verified that fly ash does not dissolve in the carbonate eutectic melt and therefore will not interfere with SO2 removal (Kaplan, Wachtel, and Lubomirsky 2013). Here, we present results of laboratory pilot unit, i.e. 13.22 kg of melt and 15,300 l of industrial flue gas containing 80 ± 2 ppm SO2 scrubbing with either CO or natural gas regeneration, and semi-industrial scale unit (271.26 kg of the eutectic carbonate melt and flue gas containing 0.15% SO2, 13 ppm NO, 52 ppm NO2, with volume 12.87 m3/min passed through the melt). In the laboratory pilot unit, in neither case did the post-scrubbing amount of SO2 remaining in the flue gas exceed 1.5–2.0 ppm. In the all tests, sulfur extraction from flue gas to the carbonate melt was >90–95% and nitrogen oxides extraction from flue gas to the carbonate melt was 60%. Sulfur and nitrogen oxides extraction from carbonate–sulfate–nitrite melt during regeneration stage was >99%.
Syngas cleaning for coal to methanol demo plant – H2S and COS removal
Published in Chemical Engineering Communications, 2021
Aykut Argonul, Omer Orcun Er, Ufuk Kayahan, Alper Unlu, Mustafa Ziypak
Furthermore, gas samples taken by using a portable gas conditioning apparatus were stored in gas bags/cylinders, and were then (one day later) analyzed for permanent gases and sulfur components by GC’s and UV-fluorescence in TUBITAK MRC laboratories. The syngas collected with sampling bags/cylinders were analyzed using an Agilent 6890 N Gas Chromatograph equipped with an FPD Detector. For chromatographic separation, a DB-1 capillary column (105 m × 0.53 mm ID, 5 µm film thickness, Agilent Technologies) was used. The total run time was 22 min: the column temperature was held at 60 °C for 3 min, it was ramped up to 130 °C over 7 min (10 °C/min) and then kept at 130 °C for another 12 min. The gas chromatograph was calibrated with a gas mixture containing hydrogen sulfide (H2S), carbonyl sulfide (COS), methyl mercaptan (CH4S), ethyl mercaptan (C2H6S), carbon disulfide (CS2) and thiophene (C4H4S). The UV-fluorescence measurements were performed by an Analytic Jena multi EA® 5000 Total Sulfur (TS) measuring device.
Sulfur conversions during coal char gasification with a two-stage air supply in a pilot-scale circulating fluidized bed gasifier
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Zhen Chai, Zhiping Zhu, Xiaofang Wang, Kun Wang
In coal char produced from low-temperature pyrolysis of coal, the main chemical forms of sulfur exist as organic sulfur of high thermally stable, sulfides (the major form is pyrites), and sulfates (Attar 1978). During gasification process, the remaining forms of sulfur transform to gas gradually by reaction with gasification agent or decompose. In producer gas, hydrogen sulfide (H2S) is a prominent sulfur-containing compound, followed by carbonyl sulfide (COS) (Andrea, Eva, and Eliseo 2016), and little carbon disulfide (CS2) can be found. Many measures have been used to remove sulfur in producer gas, but there is an obvious weakened desulfurizing effect for COS removal than that for H2S. Therefore, more efforts should be taken on the sulfur orientation control to reduce COS to cut the desulfurizing cost.