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Mass Transfer in Chemical Engineering Processes Part 7

Tham khảo tài liệu 'mass transfer in chemical engineering processes part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 140 Mass Transfer in Chemical Engineering Processes Ha Henry s constant of component A yA Molar concentration of component A in gas phase xA Mass concentration of component A in liquid phase It is determined in a temperature and pressure controlled close box by measuring the equilibrium concentration of the component in both gas and liquid phase. Therefore it requires spectrophotometric or chromatographic analysis to determine component concentration in the liquid phase Wark 2000 . It has been observed that H2S concentrations in amines solutions are highly sensible to pressure and temperature making spectrophotometric or chromatographic analysis hardly suitable for this application. For this reason literature does not report amines H2S and CO2 absorbing capacity. As an alternative it was proposed to determine the H2S and CO2 absorbing capacity of the amines by using the gas bubbler setup illustrated in figure 1. This set up looks for a full interaction of the gas stream with the absorbing substance such that it can be assumed thermodynamic equilibrium at the liquid-gas inter phase. Experiments are conducted under standard conditions of pressure and temperature 101 kPa 25oC . To ensure constant temperature for exothermic or endothermic reactions the set up is placed inside a controlled temperature water bath. Temperature pressure gas flow and degree of water dilution of the absorbing substance are measured. The amount of solution in the bubbler is kept constant in 0.5 L. Table 4 describes the variables measured and their requirements in terms of resolution and range. Fig. 1. Setup to determine the absorbing capacity of gas-phase components by liquid phase absorbers in the bubbling method. Several tests were conducted to verify reproducibility of the method. Figure 2 shows the results obtained in terms of absorbing efficiency vs. time. Absorbing efficiency yf is defined as y - y hf - yi 2 Removal of H2S and CO2 from Biogas by Amine Absorption 141 Where yi H2S molar .