Supporting Information

Transcription

1 Supporting Information Mass transfer studies in a pilot scale RPB with different packing diameters Kolja Neumann a,*, Sira Hunold a, Michiel de Beer c, Mirko Skiborowski a, Andrzej Górak a,b a TU Dortmund University, Department of Biochemical and Chemical Engineering, Laboratory of Fluid Separations, Emil-Figge-Straße 70, Dortmund, Germany b Lodz University of Technology, Faculty of Process and Environmental Engineering, Department of Environmental Engineering, Wólczańska 213, Lódz, Poland c AkzoNobel Research, Development & Innovation, Process Technology SRG, Zutphenseweg 10, 7418 AJ Deventer, The Netherlands * Corresponding author. Tel.: ; Fax: address: kolja.neumann@bci.tu-dortmund.de S1

2 APPENDIX S1: Calculation methods Table S1: Calculation methods applied to determine the physical and chemical properties. Property Phase Method/ Publication Density Gas Ideal gas law Liquid DIPPR Diffusion coefficient Liquid Modified Stokes-Einstein 2,3 Viscosity Liquid DIPPR Henry coefficient Danckwerts 3,4 Reaction rate constant Pohorecki 3 as proposed by Kunze et al. 1 S2

3 Appendix S2: Negligence the gas side mass transfer resistance. Several authors stated that the liquid side volumetric mass transfer coefficient k L a eff in RPBs substantially exceeds that in conventional packed columns 5,6,7,8. Consequently, for the same concentrations and gas and liquid loads, the Hatta number is expected to be lower in RPBs than in conventional columns. The estimation of k L in RPBs is difficult, since in the literature different packings (i.e., glass beads 6, stainless steel meshes 9 and metal foams 10 ) and different rotor configurations types (i.e. radial packing width ranging from 10 mm to 83 mm) were investigated. Furthermore, only k L a eff values have been reported and k L must be derived by an approximation of a eff. For a foam packing with a porosity of 0.9 and specific surface area of 1700 m 2 m -3 the packing characteristics are comparable to the packing characteristics of the knit meshes investigated in the present study. Shivare et al. 7 reported a maximal k L a eff of 0.6 s -1 for a radial packing width of 45 mm at a rotational speed of 30 s -1. No values for a eff were given. Rajan et al. 10 reported values of a eff for a metal foam with similar characteristics as the metal foam investigated by Shivare et al. 7. For a rotational speed of 26.7 s -1, a eff was determined to approximately 700 m 2 m -3. With these values, k L a eff from Shivare et al. 7 and a eff from Rajan et al. 10 and a hydroxide concentration of 1 mol L -1, a Hatta number of 5.1 is obtained. Larger values of a eff, as found in the present study, lead to even larger Hatta numbers. Therefore we assume that the condition of Ha > 3 is valid. With these assumptions, a eff can be estimated according to Eq.(5) 11, neglecting the gas side mass transfer resistance. By neglecting the gas side mass transfer resistance, only one test system is required. These values of a eff can be used for a rough comparison among different mass transfer equipment 1. For precise determination of k G, a different test system (e.g., the absorption of SO 2 in aqueous sodium hydroxide 1 ) would have to be investigated using the same experimental setup 12. The exclusion of the gas-side mass transfer limitation can further be justified based on the investigations of Weimer and Schaber 13, who performed a sensitivity analysis to quantify the influence of k G on the determination of a eff for conventional columns. They found the influence to be of minor importance for values of k G above m s -1. Considering again the volumetric gas side mass transfer coefficient k G a eff in RPBs reported by Shivare et al. 7, who investigated SO 2 absorption in sodium hydroxide solution, a minimum value of approximately 50 s -1 is reported for k G a eff. Therefore, effective interfacial areas of up to 2000 m 2 m 3 would be feasible to still fulfil the condition of k G larger than m s -1. All values for a eff reported by Rajan et al. 10 are below this limit, indicating that k G can be neglected. In addition, neglecting k G results in an underestimation of a eff and is a conservative approximation 13. S3

4 Appendix S3: Packing characteristics The porosity of the installed packing is calculated according to Eq.(S1). m pack ε = 1 ρ pack V Rotor (S1) To determine the specific surface area of the packing the definition of Blass 14 for an ideal wire mesh, given in Eq.(S2), is used. a P,calc = 4 d wire (1 ε) (S2) Figure S1: Structure of the knit mesh used for the experimental investigations S4

5 a eff /m 2 m -3 Appendix S4: Temperature dependency According to the criterion given by Last et al. 11, a eff does not depend on the reaction rate in a range from m 3 kmol -1 s -1 to approximately m 3 kmol -1 s -1. The experiments to derive the data points given in Figure S2 were obtained with liquid inlet temperatures of 26 C, 30 C and 34 C. The feed tanks were heated by barrel heaters and the liquid inlet temperature was measured in the feed pipe close to the liquid distributors. The experiments to evaluate the influence of the reaction rate constant were performed with a rotor configuration slightly different to the rotor configurations discussed in the present study. Instead of an axial height of 0.01 m, for these experiments a rotor with an axial height of m was investigated. Since the liquid distribution was designed for an axial packing height of 0.01 m, the effective interfacial area determined for the rotor with an axial height of m is reduced due to maldistribution. Due to this maldistribution the values of the effective interfacial area are lower for the rotor with h R = m. Nevertheless, the nonsensitivity of the effective interfacial area on the reaction rate constant, as illustrated in Figure S2, is also expected to be valid for rotors with 0.01 m axial height x10 4 2x10 4 3x10 4 4x10 4 k OH - /m 3 kmol -1 s -1 R600 with h R = m; n rot = 10 s -1 R600 with h R = m; n rot = 20 s -1 Figure S2: Measured effective interfacial area for different reaction rate constants for F G,ICA = 1.2 Pa 0.5 and LL ICA = 25 m 3 m 2 h -1. S5

6 power consumption motor P el /kw Appendix S5: Power consumption The power consumption caused by the acceleration of liquid in the rotor is calculated according to Eq.(S3). The maximal power consumption is kw (n rot = 25 s-1; r O = 0.28; V L= 0.2 m 3 h -1 ). Related to the electrical power consumption, this contribution is negligible. ζ L = 0.5 ρ NaOH V L (r O ω) 2 = kg m m3 h 1 (0.28 2π 25) 2 m 2 s 2 = kw (S3) During the experimental runs, the power consumption was read from the frequency inverter. For the investigated range of gas capacity factors and liquid loads no dependency of the power consumption on these operating parameters was observed. The power consumption mainly depends on the friction in the bearings. A dependency on the outer rotor diameter was not observed. From the experimental data given in Figure S3 the best fit line was determined (see Eq.(S4)). The correlation to estimate the power consumption that was published by Singh et al. 15 is not applicable to estimate the power consumption of the investigated pilot-scale RPB. The contribution of the electrical power consumption and the specific energy input to the total energy input for the R360 and R560 are illustrated in Table S2. P el = n rot (S4) rotational speed n rot /s -1 R560 R360 Best fit line Figure S3: Power consumption as a function of the rotational speed. The best fit line was determined by Eq.(S4). S6

7 tot / kw m -2 Table S2: Energy dissipated per generated interfacial area. ξ el,diss was calculated using the best-fit line obtained from Figure S3 and given in Eq.(S4). Operating conditions: F G,ICA = 1.8 Pa 0.5 and LL ICA = 38 m 3 m -2 h -1 Rotor configuration F G,int /Pa 0.5 a C,int a eff p /m 3 s -2 /m 2 m -3 /Pa ξ G,diss /a eff /kw m -2 P el /a eff /kw m -2 R ± ± ± ± ± ± ± ± ± ± ± ±0.07 R ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± a C,int /m 3 s -2 P el /a eff /a P G,diss /a eff Figure S4: R360 rotor: Energy dissipated by the motor and due to the pressure drop as a function of the integrated centrifugal acceleration. S7

8 tot / kw m a C,int /m 3 s -2 P el /a eff /a P G,diss /a eff Figure S5: R560 rotor: Energy dissipated by the motor and due to the pressure drop as a function of the integrated centrifugal acceleration. S8

9 Appendix S6: Standardised equipment Table S3: Requirements for standardised experimental setups given by Hoffmann et al. 12 Requirement Considered? Details Isothermal experiments Yes Verified by measurements Minimized wall effects No Effect not quantified in RPBs Avoidance of evaporation Yes Pre-saturation of the gas flow Uniform initial gas and liquid distribution (Yes) Intense mixing of gas in the casing and the liquid in the inlet of the packing assumed for rotational speeds larger than 20 s -1. Consideration of absorption in casing Measureable clean gas composition Uniform packing height and packing Representative gas and liquid samples Yes Yes No (Yes) Measurement of the CO2 concentration in the gas phase in the casing Sufficiently high raw gas composition in inlet and outlet No standardised RPB setup available No measurement along the radius possible Liquid phase concentration measured by titration is linked with large errors S9

10 Appendix S7: RPB setups Table S4: Experimental setups investigated by Singh et al. 15 and Kelleher and Fair 16. di do hr ap FG,ICA LLICA Name R457 R762 R600 / m / m / m Packing type Foam Foam Foam / m² m³ ε / / Pa / m 3 m 2 h not specified Author S10

11 1 LIST OF REFERENCES (1) Kunze, A. K.; Lutze, P.; Kopatschek, M.; Maćkowiak, J. F.; Maćkowiak, J.; Grünewald, M.; Górak, A. Mass Transfer Measurements in Absorption and Desorption. Chem. Eng. Res. Des. 2015, 104, 440. (2) Nijsing, R. A. T. O.; Hendriksz, R. H.; Kramers, H. Absorption of CO 2 in Jets and Falling Films of Electrolyte Solutions, with and without Chemical Reaction. Chem. Eng. Sci. 1959, 10, 88. (3) Pohorecki, R.; Moniuk, W. Kinetics of Reaction Between Carbon Dioxide and Hydroxyl Ions in Aqueous Electrolyte Solutions. Chem. Eng. Sci. 1988, 43, (4) Danckwerts, P. V. Gas-Liquid Reactions; McGraw-Hill: New York, (5) Munjal, S.; Duduković, M. P.; Ramachandran, P. Mass-Transfer in Rotating Packed Beds II. Experimental Results and Comparison with Theory and Gravity Flow. Chem. Eng. Sci. 1989, 44, (6) Chen, Y. S.; Lin, F. Y.; Lin, C. C.; Tai, C. Y. D.; Liu, H. S. Packing Characteristics for Mass Transfer in a Rotating Packed Bed. Ind. Eng. Chem. Res. 2006, 45, (7) Shivhare, M. K.; Rao, D. P.; Kaistha, N. Mass Transfer Studies on Split-Packing and Single-Block Packing Rotating Packed Beds. Process Intensification by Alternative Energy Forms and Transfer Mechanisms 2013, 71, 115. (8) Keyvani, M.; Gardner, N. C. Operating characteristics of Rotating Beds. Technical Progress Report prepared for US Department of Energy Pittsburgh Energy Technology Center, Pittsburgh, PA. DOE # DE-FG22-87PC 79924, (9) Chen, Y. S.; Lin, C. C.; Liu, H. S. Mass Transfer in a Rotating Packed Bed with Various Radii of the Bed. Ind. Eng. Chem. Res. 2005, 44, (10) Rajan, S.; Kumar, M.; Ansari, M. J.; Rao, D. P.; Kaistha, N. Limiting Gas Liquid Flows and Mass Transfer in a Novel Rotating Packed Bed (HiGee). Ind. Eng. Chem. Res. 2011, 50, 986. (11) Last, W.; Stichlmair, J. Determination of Mass Transfer Parameters by Means of Chemical Absorption. Chem. Eng. Technol. 2002, 25, 385. S11

12 (12) Hoffmann, A.; Maćkowiak, J. F.; Górak, A.; Haas, M.; Löning, J.-M.; Runowski, T.; Hallenberger, K. Standardization of Mass Transfer Measurements: A Basis for the Description of Absorption Processes. Chem. Eng. Res. Des. 2007, 85, 40. (13) Weimer, T.; Schaber, K. Ermittlung effektiver Phasengrenzflächen durch Kohlendioxidabsorption aus Luft. Technische Chemie 1996, 48, 241. (14) Blass, E. Geometrische und strömungstechnische Untersuchungen an Drahtgeweben. Chem. Eng. Tech. 1964, 36, 747. (15) Singh, S. P.; Wilson, J. H.; Counce, R. M.; Lucero, A. J.; Reed, G. D.; Ashworth, R. A.; Elliott, M. G. Removal of Volatile Organic Compounds from Groundwater using a Rotary Air Stripper. Ind. Eng. Chem. Res. 1992, 31, 574. (16) Kelleher, T.; Fair, J. R. Distillation Studies in a High-Gravity Contactor. Ind. Eng. Chem. Res. 1996, 35, S12