CHE368- Separation Processes PDF

CHE368- SEPARATION PROCESSES ABSORPTION & STRIPPING Separation Processes Group_1  ABSORPTION Absorption is a crucial unit operation in chemical engineering used for separating substa...

CHE368- SEPARATION PROCESSES ABSORPTION & STRIPPING Separation Processes Group_1  ABSORPTION Absorption is a crucial unit operation in chemical engineering used for separating substances. In the context of gas absorption, one or more components of a gas stream are removed by being absorbed onto a non-volatile liquid, known as a solvent. The solvent acts as the separating agent in this process ABSORPTION PROCESSES CAN BE CLASSIFIED BASED ON THE INTERACTION BETWEEN THE ABSORBENT AND ABSORBATE INTO THREE TYPES: Physical Solution: The absorbate is more soluble in the absorbent than other gases and does not chemically react with it. The equilibrium concentration depends on the gas phase partial pressure and temperature. Reversible Reaction: A chemical reaction occurs between the absorbate and the absorbent, forming a compound with a significant vapor pressure.  Irreversible Reaction: The reaction between the absorbate and absorbent is essentially permanent. Physical absorption is preferred for large quantities of gases at high pressure, while chemical absorption is used for separating components present in small concentrations at low partial pressures. ABSORPTION OPERATION Absorption operations are conducted in equilibrium stages where liquid and vapor phases are in contact. Unlike distillation columns, absorption and stripping columns are simpler and do not require condensers and reboilers. The process involves passing the gas mixture through an absorber where a liquid- phase solvent absorbs the desired component. The resulting saturated solvent is then passed through a stripper to remove the absorbed component using a stripping gas, such as steam.  EQUIPMENT GAS ABSORBER PUMPS AND Essential equipment where the gas mixture VALVES contacts a liquid-phase solvent, enabling the Circulate solvent between absorber and solvent to absorb and separate the gaseous stripper, control flow of solvent and gases, component, designed for maximum gas-liquid and maintain process efficiency through contact. adjustable operating conditions. STRIPPING COLUMN HEAT EXCHANGERS Used for physical separation, where one or Optimize energy usage by transferring heat more components are removed from a liquid between the hot solution from the stripper stream by a vapor stream. In industrial and the saturated solution entering the applications, the liquid and vapor streams absorber, enhancing system efficiency. can have co-current or countercurrent flows. Stripping works on the basis of mass transfer. MONITORING AND CONTROL SYSTEMS HEATER Essential for regulating temperature, Ensures the saturated solvent from the pressure, flow rates, and concentrations, absorber reaches the required temperature ensuring smooth and efficient absorption and for efficient stripping, crucial for effective stripping processes. absorption and stripping operations.  STRIPPING A SEPARATION PROCESS WHERE A COMPONENT IS REMOVED FROM A LIQUID MIXTURE BY CONTACTING IT WITH A GAS. THE GAS, OFTEN REFERRED TO AS THE STRIPPING AGENT, FACILITATES THE TRANSFER OF THE COMPONENT FROM THE LIQUID PHASE TO THE GAS PHASE.  MASS TRANSFER FUNDAMENTALS Mass transfer in stripping involves the movement of a component from the liquid phase to the gas phase. This process is driven by the concentration gradient and governed by mass transfer coefficients.  STRIPPING OPERATION Stripping Agents: Design of Stripping Operating Conditions: Columns: Common stripping agents Optimal temperature, include: 1.Column Height and pressure, and flow rates of 1. Steam: Frequently used Diameter: Influences the the liquid and stripping contact time and efficiency agent are crucial for due to its high heat of separation. efficient stripping. These capacity and availability. 2.Packing Type: Affects the conditions must be carefully 2. Air: Used for stripping controlled to achieve the volatile organic compounds surface area available for desired separation. (VOCs) from water. mass transfer  EQUIPMENTS Column Internals: 1.Packing Materials: Provide a large surface area for contact between the liquid and gas phases. 2.Tray Types: Include bubble cap, sieve, and valve trays, each offering different advantages. Ancillary Equipment: 1. Reboilers: Supply heat to the bottom of the stripping column. 2. Condensers: Cool and condense the stripped vapor for further processing or disposal.  PRINCIPLES OF STRIPPING THERMODYNAMIC PRINCIPLES: 01 02 Henry's Law: Describes the Raoult's Law: Relates the partial solubility of gases in liquids at pressure of a component in the constant temperature. vapor phase to its mole fraction in the liquid phase.  Assumptions: Absorption and stripping typically involve: Insoluble carrier gas: The carrier gas does not dissolve in Three components: solute, the solvent. carrier gas, and solvent Non-volatile solvent: The Two phases: gas and liquid solvent doesn't evaporate significantly. Isothermal and isobaric conditions: Constant temperature and pressure. KEY FACTORS FOR SOLVENT SELECTION Solubility: High solubility for the target gas, low solubility for carrier gas. Viscosity: Low viscosity for efficient mass transfer and reduced energy consumption. Corrosiveness: Non-corrosive or minimally corrosive to equipment. Cost: Economically viable. Safety: Non-toxic, non-flammable, and non-hazardous. MASS BALANCE SUMMARY: THANK YOU! REFERENCES: (1) Lamm, M., & Jarboe, L. (2021, August 25). Absorption and stripping. Pressbooks. https://iastate.pressbooks.pub/chemicalengineeringseparations/chapter/absorption-and-stripping/? fbclid=IwZXh0bgNhZW0CMTAAAR1ArQG7nWmb1Dg7tYYxr-ddusud_FB6Ymc8u1TpCLra6Bp3PGeS- SDZQ44_aem_5Wl3832Gh8qtDWelZhwknA (2) Chemical Engineering. (2023, January 27). Absorption working principle, Chemical Engineering, Mass Transfer [Video]. YouTube. https://www.youtube.com/watch?v=-2CpjWDaAQY (3) Absorption vs. Stripping - What’s the Difference? | This vs. That. (n.d.-b). This Vs. That. https://thisvsthat.io/absorption-vs- stripping ADSORPTION GROUP 4 SEPARATION PROCESS  OBJECTIVES 01 Separation by Adsorption 04 Selection of Appropriate Adsorption Cycle 02 Selection of Sorbent 05 General Design Concepts 03 Basic Adsorption Cycles 06 Cost for Adsorption Equipments  SEPARATION BY ADSORPTION ADSORPTION refers to the accumulation of molecules or particles on the surface of a material. Adsorption involves molecules, atoms, or ions attaching to a solid surface via weak forces involves the transfer of components from a fluid phase (gas or liquid) onto a solid adsorbent surface. 01 Adsorbate refers to the substance being adsorbed Adsorbent is the solid material. Adsorption is about sticking to the surface, while Absorption is about getting absorbed inside. Surface Area Enhancement Energy Considerations Regeneration Cycle Design Implications Classification of Adsorption Processes SEPARATION BY ADSORPTION CHARACTERISTICS OF SUITABLE SORBENTS PREDOMINANTLY USED ADSORBENT TYPES - ACTIVATED CARBON - MOLECULAR SIEVE ZOELITES (MSZ) - SILICA GEL - ACTIVATED ALUMINA APPLICATIONS AND CONSIDERATIONS CONCLUSION - understanding the specific properties and applications of each adsorbent type is crucial for selecting the right material in industrial processes. - optimization of adsorbent performance. 02  BASIC ADSORPTION CYCLES Unlike distillation Adsorption operates with various physical arrangements and cycles. 1. Temperature-Swing Cycle 2. Inert-Purge Cycle 3. Displacement Purge Cycle 4. Pressure Swing Cycle 03 TEMPERATURE-SWING CYCLE X1- generally expressed in units of weight of adsorbate Involves passing a feed stream through an per weight of adsorbent adsorption bed at a certain temperature, X2 - New Equilibrium allowing adsorbate to reach equilibrium on the adsorbent. Regeneration requires heating the bed, causing desorption. Typical removal capacity exceeds 1 kg of adsorbate per 100 kg of adsorbent. It is energy-intensive and suitable for low X1-X2 net removal capacity adsorbate concentrations due to its long regeneration time. Widely used in chemical, petrochemical and environmental sectors for high-purity separations  INERT-PURGE CYCLE Uses a nonadsorbing gas to purge adsorbate from the bed by lowering its partial pressure, facilitating desorption. Cycle times are short, often a few minutes. Limited to 1-2 kg of adsorbate per 100 kg of adsorbent due to reduced adsorption capacity at higher temperatures. well suited for applications where rapid regeneration and More Energy-efficient than low energy costs are crucial temperature-swing DISPLACEMENT PURGE CYCLE Uses a gas or liquid that adsorbs similarly to the adsorbate for regeneration. Competitive adsorption and reduced partial pressure facilitate desorption. Cycle times are short, maintaining nearly isothermal conditions. Higher adsorbate loading than the inert-purge cycle due to negligible net heat change requires energy to pump and circulate purge fluid high efficiency and rapid separation are essential  PRESSURE-SWING CYCLE Reduces the adsorbate's partial pressure by lowering the total pressure of the gas. Efficient in bulk-gas separation Adsorbate loading and regeneration occur quickly, making it suitable for bulk-gas separations despite lower adsorbate loadings ( 1, q’ = q’max. At intermediate pressures, the equation is nonlinear. 05 Freundlich expression When n= 1, EQ 15-72 reduces to Henry's law relation. For a binary gas mixture in which components A and B are being adsorbed on the surface of an adsorbent, the equilibrium loading of each component is given by Combined Freundlich and Langmuir equation: 05 EQUILIBRIUM RELATIONS FOR ADSORBENTS The equilibrium between the concentration of a solute in the fluid phase and its concentration on the solid resembles somewhat the equilibrium solubility of a gas in a liquid. Data that follow a linear law can be expressed by an equation similar to Henry's law: 05 Freundlich isotherm equation, particularly useful for liquids: Langmuir isotherm equation. theoretical basis: As temperature is increased, the amount adsorbed by the adsorbent decreases strongly. 05  COST FOR ADSORPTION EQUIPMENTS The costs for adsorption equipment include initial capital expenses for purchasing the equipment and adsorbent materials, along with installation and integration with existing systems. Operational costs encompass adsorbent replacement or regeneration, energy consumption, and routine maintenance. Disposal costs for spent adsorbents and compliance with environmental regulations are also significant. 06  EQUIPMENT DESIGN AND COSTS FOR SEPARATING HETEROGENEOUS MIXTURES Gas-Liquid Separation Equipment: Cyclones, knockout drums, Venturis, and spray towers. Common Equipment: Knockout drums (low gas velocity allows liquid droplets to settle by gravity). Cost Factors: Addition of baffles for low liquid concentrations. Gas-Solid Separation Equipment: Cyclones, electrostatic precipitators, scrubbers, and bag filters. Efficiency: 90-99% in mass removal. Cost Factors: Energy requirement increases as particle size decreases. 06  EQUIPMENT DESIGN AND COSTS FOR SEPARATING HETEROGENEOUS MIXTURES Liquid-Liquid Separation Equipment: Decanters, hydrocyclones, and deep-bed filtration. Cost Factors: Use of coalescence promoters for smaller particle sizes. Solid-Solid Separation Techniques: Leaching, froth flotation, classifiers, concentrators, separators. Cost Factors: Crushing solid material to particle size, energy for physical separation. Solid-Liquid Separation Equipment: Settlers, filters, screens, dewatering presses, dryers, evaporators, leachers. Cost Factors: Settling characteristics, particle size, vapor pressure differences. 06 THANK YOU FOR LISTENING! ESDRELON, MARY KERSTYN CASANDRA HIDLAO, CHRISTIAN LLOYD KYAMKO, RIEL LEGADOS, RANEE JANE  CHE368 SEPARATION PROCESS EXTRACTION PRESENTED BY: ANOBA BARONG BONTILAO CATINGUB  WHAT IS EXTRACTION? Extraction is a separation process used in chemical engineering to isolate components from a mixture by utilizing a solvent. KEY CONCEPTS The principle of extraction relies on the differential solubility of compounds in two immiscible phases. Phase Equilibrium Solubility Mass Transfer Solvent Selection Factors Affecting 1. Solvent Selection: The choice of solvent is critical and depends on its selectivity, Extraction distribution coefficient, immiscibility with the feed phase, and cost. 2. Temperature: Can affect solubility, distribution coefficients, and mass transfer rates. 3. Phase Ratio: The volume ratio of the solvent to the feed phase impacts the efficiency of extraction. 4. Contact Time and Mixing: Adequate contact time and effective mixing enhance mass transfer and ensure equilibrium is reached. Industrial extraction system Such devices can be inefficient unless liquid viscosities are low and phase density differences are high. Thus, mechanically agitated devices are often better. Design engineers must evaluate the number of theoretical stages needed and determine the equipment dimensions for the extraction. OPERATIONS INVOLVED LIQUID- LIQUID EXTRACTION CONTINUOUS COUNTER-FLOW CONTRACTORS SPRAY EXTRACTION TOWERS PACKED EXTRACTION TOWERS TRAY EXTRACTION TOWERS  Spray Extraction Tower has very large axial dispersion (back-mixing) in a continuous phase. only one (1) or two (2) stages are usually present in the tower. lost cost but rarely used. can be used in rapid, irreversible chemical reaction. Packed extraction tower axial mixing is reduced. used only when few stages are needed. more efficient than spray tower. often use random packing than structured packing. flooding occurs when increasing the dispersed or continuous flowrates. Perforated-Plate (Sieve-Tray) Extraction Towers used for dispersion of liquid drops and coalescence on each tray. holes in tray are D = 0.32-0.64 cm percentage of open tray area is 15%-25% (column cross-sectional area. Tray spacings of 10-25cm are used.  CONTINUOUS COUNTERFLOW CONTRACTORS WITH MECHANICAL AGITATION PULSED PACKED AND SIEVE-TRAY TOWERS SCHIEBEL TOWER ROTATING-DISK CONTRACTOR ASYMMETRIC ROTATING-DISK KARR RECIPROCATING-PLATE TOWER  SCHIEBEL TOWER a series of rotating turbine agitators from dispersions which coalesce in passing through the knitted mesh. tower operates as a series of mixer- settler extraction units. operates with high efficiencies.  ROTATING-DISK CONTRACTOR (RDC) extensively used device worldwide horizontal disks, mounted on a centrally located rotating shaft, are the agitation elements. the ratio of disk diameter to column diameter is 0.6 ASYMMETRIC ROTATING- DISK CONTRACTOR (ARD) contact and transport zones that are separated by a vertical battle reduces back-mixing because of the separate mixing and settling compartments. KARR RECIPROCATING- PLATE COLUMN (RPC) uses less energy than pulsing the entire volume of liquid. the central shaft, which supports both sets of plate is reciprocated by a drive at the top of the column particularly useful for bio- separations due to residence time is reduced and can handle systems that tend to emulsify and feed that contains particulates MIXER-SETTLER EXTRACTION A device which comprises of a mixture for contacting the two liquid phases to effect mass transfer and a settler for mechanical separation of the phases. MIXER-SETTLERS EXTRACTION CENTRIFUGAL EXTRACTION A device using a centrifugal force to separate substances. It’s working principles is to separate substances of different densities at different position through tha action of centrifugal force. CENTRIFUGAL EXTRACTION  APPLICATIONS Chemical Metallurgy Steps: Techniques: Mining Hydrometallurgy Crushing Pyrometallurgy Grinding Electrometallurgy Concentration Smelting Refining Casting  APPLICATIONS Pharmaceuticals Methods: Maceration Infusion Digestion Decoction Percolation Soxhlet Hot Continuous Extraction  REFERENCES Peters, M. S., Timmerhaus, K. D., & West, R. E. (2002). Plant design and economics for chemical engineers (5th ed.). McGraw-Hill Professional. Geankoplis, C. J, Transport Processes and Separation Process Principles, 4th edition, Prentice Hall, 2003 Technoforce Solutions (I) Pvt Ltd. (2018, April 2). Liquid Liquid Extraction [Video]. YouTube. https://www.youtube.com/watch?v=Vth7B9HFmto RAMREDDY PHARMA. (2024a, March 3). LIQUID-LIQUID EXTRACTION [Video]. YouTube. https://www.youtube.com/watch?v=nyEJH0dcN-E Chemical Engineering. (2020, December 24). Lecture 3 Mechanically agitated LLE equipment description [Video]. YouTube. https://www.youtube.com/watch? v=jKDisjMIUTc THANK YOU! END SLIDE