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Absorption Column: Foundations, Applications and Scientific Progress
The document discusses the theory and application of absorption columns in chemical engineering, focusing on their roles in gas separation and purification processes. It outlines various types of absorption methods, design considerations, current research trends, and challenges related to efficiency and solvent regeneration. The conclusion emphasizes the importance of optimizing mass transfer in absorption columns for effective gas cleaning applications.
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Absorption Column: Foundations, Applications and Scientific Progress
- 1. ABSORPTION COLUMN: FOUNDATIONS, APPLICATIONSAND SCIENTIFIC PROGRESS 1 UNIT OPERATIONS LAB II UNITOPERATION:ABSORPTION
- 2. ABSORPTION COLUMN IRIS BUSTAMANTEPÁJARO* ANGIE CASTILLO GUEVARA* ALVARO JOSE GARCÍA PADILLA * KARIANA ANDREA MORENO SADDER* 9th SEMESTER CHEMICAL ENGINEERING PROGRAM UNIVERSITY OF CARTAGENA 2 UNIT OPERATIONS LAB II UNITOPERATION:ABSORPTION
- 3. 3 UNITOPERATION:ABSORPTION OUTLINE 1. Introduction 2. Theoreticalfoundations 3. Applications 4. Limitations 5. Current researches 6. Objectives & Methodology 7. Results & Discussion 8. Conclusion Acknowledgements ABSORPTION COLUMN: FOUNDATIONS, APPLICATIONS AND SCIENTIFIC PROGRESS "Good, better, best. Never let it rest. 'Til your good is better and your better is best." - St. Jerome
- 4. 4 UNITOPERATION:ABSORPTION INTRODUCTION UNIT OPERATION ABSORPTION It’s theremoval of a solute (component) from its gaseous mixture using a solvent. Importance: Gas absorption processes are widely used in the industry, mainly for environmental regulations of gaseous emissions. Chemical engineer, job duties: Design, simulate, develop & operate absorption unit, where mass transfer phenomena take place. Shreve’s et al., 1955; Ocon Tojo et al., 2001; Wang et al., 2014; Geankoplis, 1993 Important unit operation encountered in both CPIs and PCIs
- 5. 5 UNITOPERATION:ABSORPTION MAIN TYPES Types ofabsorption extensively applied in laboratory and industrial processes CHEMICAL ABSORPTION Amine processes Carbonate processes PHYSICAL ABSORPTION Selexol Purisol Rectisol, sulfinol Only physical and is limited by the formation of solution of the gas in the liquid Absorption follows incipient chemical reaction Chattopadhyay et al., 2007
- 6. 6 UNITOPERATION:ABSORPTION THEORETICAL FOUNDATIONS Chemical solventsPhysicalsolvents Chattopadhyay et al., 2007 • MEA • DGA • DEA • MDEA • Dimetil de polietilenglicol • Metanol • NMP • Propilencarbonato ELECTION OF THE SOLVENT High selectivity High solubility Low volatility Low viscosity Water is the solvent most commonly used.
- 7. 7 UNITOPERATION:ABSORPTION DISTILLATION-ABSORPTION Chattopadhyay et al.,2007 DISTILLATION ABSORPTION Stripping vapor is generated by the partial evaporation of the liquid. The liquid is always well below its boiling point. Simultaneous molecular diffusion in both directions. Diffusion is chiefly unidirectional. The radio of the liq flowrate to the gas flowrate is minor. The radio of the liq flowrate to the gas flowrate is greater tan distillation. The primary objective is to involve separation of solutes from each other to any important extent. The primary objective is only solute recovery or solute removal. Table 1. Comparison between distillation and absorption process
- 8. 8 UNITOPERATION:ABSORPTION CONVENTIONAL COLUMNS Bruinsma etal., 2012; Li et al., 2017 PACKED TOWER ADVANTAGES DISADVANTAGES Source: Copyright Tri-Mer Corporation, Owosso Superior contact between gases and liquid that promote high mass transfer rate. Low capital, operating, and maintenance cost. Channeling, which must be controlled by redistributing liquid Cannot handle extremely high or low flow rates
- 9. 9 UNITOPERATION:ABSORPTION CONVENTIONAL COLUMNS Ensure alarge area of contact between fluids Encourage the mass transfer of one or more components from one fluid to another What causes pressure drop in a packed tower? The packing of the column For absorption, the tower should be designed using about 50-70% of the gas flood velocity with the high value used in high flow parameters PACKAGE The fluid velocity Chattopadhyay et al., 2007
- 10. 10 UNITOPERATION:ABSORPTION CONVENTIONAL COLUMNS PACKING MATERIALAND SHAPES Economic Inert High resistance to deformation and corrosion McCabe et al., 2007
- 11. 11 UNITOPERATION:ABSORPTION CONVENTIONAL COLUMNS DESIGN OFA PACKED ABSORPTION COLUMN Balance around the dotted line 𝐿2 , 𝑥2 Operating line 𝑉, 𝑦 𝑉2 , 𝑦2 𝐿, 𝑥 𝐿1 , 𝑥1𝑉1 , 𝑦1 𝐿´ 𝑥2 1 − 𝑥2 + 𝑉´ 𝑦1 1 − 𝑦1 = 𝐿´ 𝑥1 1 − 𝑥1 + 𝑉´ 𝑦2 1 − 𝑦2 𝐿´ 𝑥 1 − 𝑥 + 𝑉´ 𝑦1 1 − 𝑦1 = 𝐿´ 𝑥1 1 − 𝑥1 + 𝑉´ 𝑦 1 − 𝑦 Total matter balance for component A 𝑑𝑧𝑧 Geankoplis, 1993
- 12. UNITOPERATION:ABSORPTION CURRENT RESEARCHES WETTED WALLCOLUMN H.A. Rodríguez et al. 2013; Bruinsma et al., 2012; Li et al., 2017 10 Source: H.A.Rodríguez et al. 2013 ADVANTAGES DISADVANTAGES Can neutralize corrosive gas Can be used in a multi-staged configuration Complex design High maintenance costs
- 13. 13 UNITOPERATION:ABSORPTION CONVENTIONAL COLUMNS Li etal., 2017 TRAY TOWER ADVANTAGES DISADVANTAGES Source: Copyright Tri-Mer Corporation, Owosso Can handle high or low liquid flow rates cost effectively. Easily customized to specific requirements such as operations requiring much heat Higher pressure drops than packed columns Slow reaction rate processes Plugging and fouling may occur
- 14. 14 UNITOPERATION:ABSORPTION CONVENTIONAL COLUMNS DESIGN OFTRAY ABSORPTION COLUMN Balance around the dotted line N 𝐿0 , 𝑥0 𝑁 − 1 Operating line 𝑛 + 1 𝑉1 , 𝑦1 𝐿 𝑛 , 𝑥 𝑛𝑉𝑛+1 , 𝑦 𝑛+1 1 2 n 𝐿 𝑁 , 𝑥 𝑁𝑉𝑁+1 , 𝑦 𝑁+1 𝐿´ 𝑥0 1 − 𝑥0 + 𝑉´ 𝑦 𝑁+1 1 − 𝑦 𝑁+1 = 𝐿´ 𝑥 𝑁 1 − 𝑥 𝑁 + 𝑉´ 𝑦1 1 − 𝑦1 𝐿´ 𝑥0 1 − 𝑥0 + 𝑉´ 𝑦 𝑛+1 1 − 𝑦 𝑛+1 = 𝐿´ 𝑥 𝑛 1 − 𝑥 𝑛 + 𝑉´ 𝑦1 1 − 𝑦1 Geankoplis, 1993
- 15. 15 UNITOPERATION:ABSORPTION CONVENTIONAL COLUMNS 𝑦1 𝑦2 0 𝑥2 𝑥1 Operatingline Balance line Molarfraction,y Molar fraction, x 𝑦2 𝑦1 0 Balance line Operating line Figure 1. Location of operation lines: a) for absorption of A from V to the current L, and b) for rectification of A from L to the current V a) b) Molarfraction,y Molar fraction, x 𝑥1 𝑥2
- 16. UNITOPERATION:ABSORPTION CONVENTIONAL COLUMNS SPRAY COLUMNS DISADVANTAGES Bruinsmaet al., 2012; Li et al., 2017 10Source: Thermische VerfahrensTechnik ADVANTAGES Low pressure drop Most effective for solutes with high liquid solubility High pumping cost Poor mass transfer Low residence times
- 17. 17 UNITOPERATION:ABSORPTION APPLICATIONS SEPARATION PROCESSES Geankoplis etal., 2006 Coke plants Air pollution control Hydrogenation of oils Wastewater treatment and pollution control
- 18. 18 UNITOPERATION:ABSORPTION APPLICATIONS Geankoplis et al.,2006 The petrochemical industry The chemical industry Food processingProcess membrane
- 19. 19 UNITOPERATION:ABSORPTION LIMITATIONS Chattopadhyay et al.,2007; Narimani et al., 2017; Hassan et al., 2016 ABSORPTION DISADVANTAGE Low biodegradation of absorbents Nagging problems of corrosion Source: www.encyclopedia.che.engin.umich.edu Much energy-intensive for the regeneration of solvents
- 20. UNITOPERATION:ABSORPTION CURRENT RESEARCHES 10 Removal efficiencyof SO2 for various absorbents. Source: Rahmani et al, 2015. Solubility study in a flask with pressure and temperature indicators. Rahmani et al., 2015 Amino acid salt Sodium based buffer solutions Sterically hindered amines Amide
- 21. UNITOPERATION:ABSORPTION CURRENT RESEARCHES 10 Variations ofremoval efficiency of SO2 with temperature. Source: Rahmani et al, 2015. Operational behavior of absorbents in packed column Rahmani et al., 2015 Why packed colum? High efficiency, high capacity, low pressure drop 𝑆𝑂2 inlet concentration 𝐿/𝐺 ratio Temperature Removal Removal Range: 0.007 − 0.008
- 22. UNITOPERATION:ABSORPTION CURRENT RESEARCHES 10 Variations of𝐾 𝐺 𝑎 𝑉 with: a) partial pressure, b)temperature. Source: Xu et al., 2016 Determination of 𝐾 𝐺 𝑎 𝑉 considering different operational parameterXu et al., 2016 Solvent: DEEAGas:𝐶𝑂2 a
- 23. UNITOPERATION:ABSORPTION CURRENT RESEARCHES 10 Comparison betweenstructured and random packing. Xu et al., 2016 Variations of 𝐾 𝐺 𝑎 𝑉 with temperature for structured and random packing. Source: Xu et al., 2016 Structured Random
- 24. UNITOPERATION:ABSORPTION CURRENT RESEARCHES 10 Removal ofCO2 and or 𝐾 𝐺 𝑎 versus liquid flow rate. Source: Xu et al, 2017. New configuration of spray towerXiaomei Wu et al., 2017 Dual-nozzle opposed impinging spray MEA Gas Solvent Diameter-varying CO2
- 25. UNITOPERATION:ABSORPTION CURRENT RESEARCHES 10 Schematic diagramof wetted-wire column (a) cropped view (b) side view . Source: Abouali et al, 2017. Abouali et al., 2016 Simulation in MATLAB Absorption system: CO2-MEA Fast reaction and gas phase mass transfer resistance Overall mass transfer coefficient Gas absorption rate Efficiency of column
- 26. UNITOPERATION:ABSORPTION CURRENT RESEARCHES 10 Comparison betweenthe predicted values and experimental data, presented by Migita et al., .Source: Abouali et al, 2017. Abouali et al., 2016 Comparison with experimental data Migita et al., 2005 Uchiyama et al., 2003 Multi-wetted-wire column One wetted-wire column
- 27. UNITOPERATION:ABSORPTION OBJECTIVES & METHODOLOGY 27 ABSORPTIONCOLUMN CALCULATIONS Variations in pH plotted Average deviation dispersion measure Standard deviation dispersion measure Percentage increase in water acidity
- 28. UNITOPERATION:ABSORPTION RESULTS & DISCUSSION 28 Thereisn’t important fluctuations in the pH of water through the time. 0 1 2 3 4 5 6 7 0 5 10 15 20 pH Time (min) pH of the liquid versus time Series1 Series2 3 SCFH 5 SCFH Variation of the pH of the water at the outlet of the absorption column with respect to the time for the carbon dioxide flow of 3 and 5 SCFH. Source: Authors.
- 29. UNITOPERATION:ABSORPTION RESULTS & DISCUSSION 29 Standarddeviation dispersion measure Percentage increase in water acidity Van Ness, 2007 𝜎 = 𝑖=1 𝑛 (𝑝𝐻𝑖 − 𝑝𝐻)2 𝑛 Average deviation dispersion measure 𝑝𝐻 = 1 𝑛 𝑖=1 𝑛 𝑝𝐻𝑖 % cambio pH = 𝑝𝐻 𝑓𝑖𝑛𝑎𝑙 − 𝑝𝐻𝑖𝑛𝑖𝑐𝑖𝑎𝑙 𝑝𝐻𝑖𝑛𝑖𝑐𝑖𝑎𝑙 ∙ 100
- 30. UNITOPERATION:ABSRPTION RESULTS & DISCUSSION 30 Average,standard deviation and % change of pH of the liquid at the outlet of the absorption column for carbon dioxide flow of 3 and 5 SCFH Flujo de CO2 (SCFH) pH promedio Desviación estándar (𝝈) % Cambio de pH 3 5.14 ±0.046 -13.18 5 4.97 ±0.064 -16.04 Little dispersion of data. Decrease in pH Increased absorption at high flow rates.
- 31. 31 UNITOPERATION:ABSORPTION RESULTS & DISCUSSION CALCULATIONOF THE DIAMETER OF A PACKED TOWER The value of the abscissa is calculated. For a given pressure drop it reads the ordinates a value for a given expression. For a given packing factor, the capacity factor is cleared. The surface velocity and the gas flow rate are determined. The area is found from the ratio of liquid flow rate and liquid velocity. The diameter of the tower is calculated Calderon & Luna, 2007
- 32. UNITOPERATION:ABSRPTION RESULTS & DISCUSSION 32 DISTRIBUTORS PLATES Facilitatethe separation of the two phases. Caicedo & Orozco, 2012Copyright Sulzer Chemtech Ltd., Switzerland
- 33. UNITOPERATION:ABSRPTION RESULTS & DISCUSSION 33 Pressuredrop versus gaseous flow Flood curve through Lobo correlation Dry & wet packing
- 34.
- 35. UNITOPERATION:ABSORPTION CONCLUSION 35 Absorption column. Source:www. spanish.alibaba.com Absorption is the one of the most commonly used separation techniques for the gas cleaning purpose for removal of various gases like H2S, CO2, SO2 and ammonia. Design of the column involves estimation of diameter of the column and height of the packing required for specified separation. An optimum transfer of mass between the liquid and gaseous phase in contact guarantees a better performance of the absorption column
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