PRESSURE SWING ADSORPTION in the UNIT OPERATIONS LABORATORY Jason C
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Molecular Sieve
Molecular Sieve Theory, Properties, and Process Optimization Hi Did you know that Molecular Sieves are… Type A • used in dehydration units or beds • also called zeolite and mole sieve • tiny, hollow crystals that separate smaller molecules from larger molecules • able to selectively adsorb Water Molecule size = 2.8A molecules due to pore diameter Molecular Sieve Pore size = 3A of the crystals Ethanol Molecule size = 3.6A You’ve probably ...this is seen its beaded or Molecular Sieve beaded form… in its crystal form Process of Making Molecular Sieve Sieve Purpose Why use Molecular Sieve • 3A Molecular Sieve breaks the ethanol/water azeotrope • Finishes dehydrating ethanol after distillation and removes final 5% of water • Allows ethanol to be used as a fuel additive Common Bed Layouts How to read a Specification Sheet How to read a Specification Sheet How to read a Specification Sheet How to read a Specification Sheet How to read a Specification Sheet THINGS TO LOOK FOR… TIME FOR A CHANGE • Frequent filter changes If you’re experiencing • Caused by dust in system these situations and you • Weak beads break and crack over time hope for improvement, • High regeneration proof you should talk to your • Caused by loss of adsorption capacity ethanol community for a • 3A can change back to 4A solution. • Rapid changes in Pressure Drop The opportunities for • Can be caused by wide bead optimization are endless. distribution • Broken and cracked beads cause irregularities • Reductions of Cycle Times Process Optimization WORKING CAPACITY • Capacity -
Solutes and Solution
Solutes and Solution The first rule of solubility is “likes dissolve likes” Polar or ionic substances are soluble in polar solvents Non-polar substances are soluble in non- polar solvents Solutes and Solution There must be a reason why a substance is soluble in a solvent: either the solution process lowers the overall enthalpy of the system (Hrxn < 0) Or the solution process increases the overall entropy of the system (Srxn > 0) Entropy is a measure of the amount of disorder in a system—entropy must increase for any spontaneous change 1 Solutes and Solution The forces that drive the dissolution of a solute usually involve both enthalpy and entropy terms Hsoln < 0 for most species The creation of a solution takes a more ordered system (solid phase or pure liquid phase) and makes more disordered system (solute molecules are more randomly distributed throughout the solution) Saturation and Equilibrium If we have enough solute available, a solution can become saturated—the point when no more solute may be accepted into the solvent Saturation indicates an equilibrium between the pure solute and solvent and the solution solute + solvent solution KC 2 Saturation and Equilibrium solute + solvent solution KC The magnitude of KC indicates how soluble a solute is in that particular solvent If KC is large, the solute is very soluble If KC is small, the solute is only slightly soluble Saturation and Equilibrium Examples: + - NaCl(s) + H2O(l) Na (aq) + Cl (aq) KC = 37.3 A saturated solution of NaCl has a [Na+] = 6.11 M and [Cl-] = -
Adsorption Basics: Part 2
Back to Basics Adsorption Basics: Part 2 Alan Gabelman, P.E. This article focuses on adsorbents, including Gabelman Process Solutions, LLC activated carbon, zeolite molecular sieves, and polymeric adsorbents, as well as ion exchange resins. dsorption is a unit operation that exploits the attrac- batch mix tank, because the high pressure drop precludes its tion of solutes in a liquid or gas to a solid surface. use in a column. Spent powdered carbon must be removed AThis attraction allows the solutes to be removed, or by filtration, and regeneration is not practical. solutes with different affinities for the solid to be separated. Activated carbon is a highly versatile adsorbent, because The first article (1) of this two-part series presented the its performance characteristics can be tailored by varying fundamentals of adsorption, including equilibrium and mass- the precursor, roasting conditions, and activation method. transfer considerations, the mass-transfer zone concept, Consequently, products are available for a wide range of breakthrough, regeneration, and column sizing. This article, applications, for treating both gases and liquids. Liquid Part 2, covers the most widely used adsorbents — in order of applications include potable water treatment (discussed decreasing commercial importance (2, 3): activated carbon, later), groundwater remediation, industrial and municipal zeolite molecular sieves, silica gel, activated alumina, and wastewater treatment, sweetener decolorization, and chemi- polymeric adsorbents — with discussion of their physi- cal and pharmaceutical processing. Examples of gas appli- cal characteristics, suitable applications, and regeneration cations are removal of organics from waste gas, capture of requirements. Ion exchange, a process that is similar gasoline vapor emissions from automobiles, and adsorption to adsorption and is used to remove ions from solution, is of gaseous radionuclides from nuclear power plants. -
Page 1 of 6 This Is Henry's Law. It Says That at Equilibrium the Ratio of Dissolved NH3 to the Partial Pressure of NH3 Gas In
CHMY 361 HANDOUT#6 October 28, 2012 HOMEWORK #4 Key Was due Friday, Oct. 26 1. Using only data from Table A5, what is the boiling point of water deep in a mine that is so far below sea level that the atmospheric pressure is 1.17 atm? 0 ΔH vap = +44.02 kJ/mol H20(l) --> H2O(g) Q= PH2O /XH2O = K, at ⎛ P2 ⎞ ⎛ K 2 ⎞ ΔH vap ⎛ 1 1 ⎞ ln⎜ ⎟ = ln⎜ ⎟ − ⎜ − ⎟ equilibrium, i.e., the Vapor Pressure ⎝ P1 ⎠ ⎝ K1 ⎠ R ⎝ T2 T1 ⎠ for the pure liquid. ⎛1.17 ⎞ 44,020 ⎛ 1 1 ⎞ ln⎜ ⎟ = − ⎜ − ⎟ = 1 8.3145 ⎜ T 373 ⎟ ⎝ ⎠ ⎝ 2 ⎠ ⎡1.17⎤ − 8.3145ln 1 ⎢ 1 ⎥ 1 = ⎣ ⎦ + = .002651 T2 44,020 373 T2 = 377 2. From table A5, calculate the Henry’s Law constant (i.e., equilibrium constant) for dissolving of NH3(g) in water at 298 K and 340 K. It should have units of Matm-1;What would it be in atm per mole fraction, as in Table 5.1 at 298 K? o For NH3(g) ----> NH3(aq) ΔG = -26.5 - (-16.45) = -10.05 kJ/mol ΔG0 − [NH (aq)] K = e RT = 0.0173 = 3 This is Henry’s Law. It says that at equilibrium the ratio of dissolved P NH3 NH3 to the partial pressure of NH3 gas in contact with the liquid is a constant = 0.0173 (Henry’s Law Constant). This also says [NH3(aq)] =0.0173PNH3 or -1 PNH3 = 0.0173 [NH3(aq)] = 57.8 atm/M x [NH3(aq)] The latter form is like Table 5.1 except it has NH3 concentration in M instead of XNH3. -
Tuning Carbon Molecular Sieve Membrane Performance for Challenging Gas Separations
TUNING CARBON MOLECULAR SIEVE MEMBRANE PERFORMANCE FOR CHALLENGING GAS SEPARATIONS A Dissertation Presented to The Academic Faculty by Graham B. Wenz In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in Chemical Engineering Georgia Institute of Technology May 2017 COPYRIGHT © 2017 BY GRAHAM B. WENZ TUNING CARBON MOLECULAR SIEVE MEMBRANE PERFORMANCE FOR CHALLENGING GAS SEPARATIONS Approved by: Dr. William J. Koros, Advisor Dr. Ryan P. Lively School of Chemical and Biomolecular School of Chemical and Biomolecular Engineering Engineering Georgia Institute of Technology Georgia Institute of Technology Dr. Peter J. Ludovice Dr. Pradeep K. Agrawal School of Chemical and Biomolecular School of Chemical and Biomolecular Engineering Engineering Georgia Institute of Technology Georgia Institute of Technology Dr. Meisha L. Shofner School of Material Science and Engineering Georgia Institute of Technology Date Approved: April 3rd, 2017 This work is dedicated to my parents. ACKNOWLEDGEMENTS This has been a journey with many ups and downs, and would not have been possible without the support of many people. First and foremost, I have to express my sincere gratitude to my advisor, Dr. William J. Koros. I am almost certain that I will never meet another human being more dedicated to their work. His combination of endless energy (coffee probably helps here), depth of knowledge and desire to “push the boundaries” has been, and will continue to be, inspirational. I can certainly say that without his guidance and support, I would not have made it to this point. I would also like to thank my Ph.D. committee members: Dr. Pradeep K. Agrawal, Dr. -
THE SOLUBILITY of GASES in LIQUIDS Introductory Information C
THE SOLUBILITY OF GASES IN LIQUIDS Introductory Information C. L. Young, R. Battino, and H. L. Clever INTRODUCTION The Solubility Data Project aims to make a comprehensive search of the literature for data on the solubility of gases, liquids and solids in liquids. Data of suitable accuracy are compiled into data sheets set out in a uniform format. The data for each system are evaluated and where data of sufficient accuracy are available values are recommended and in some cases a smoothing equation is given to represent the variation of solubility with pressure and/or temperature. A text giving an evaluation and recommended values and the compiled data sheets are published on consecutive pages. The following paper by E. Wilhelm gives a rigorous thermodynamic treatment on the solubility of gases in liquids. DEFINITION OF GAS SOLUBILITY The distinction between vapor-liquid equilibria and the solubility of gases in liquids is arbitrary. It is generally accepted that the equilibrium set up at 300K between a typical gas such as argon and a liquid such as water is gas-liquid solubility whereas the equilibrium set up between hexane and cyclohexane at 350K is an example of vapor-liquid equilibrium. However, the distinction between gas-liquid solubility and vapor-liquid equilibrium is often not so clear. The equilibria set up between methane and propane above the critical temperature of methane and below the criti cal temperature of propane may be classed as vapor-liquid equilibrium or as gas-liquid solubility depending on the particular range of pressure considered and the particular worker concerned. -
Producing Nitrogen Via Pressure Swing Adsorption
Reactions and Separations Producing Nitrogen via Pressure Swing Adsorption Svetlana Ivanova Pressure swing adsorption (PSA) can be a Robert Lewis Air Products cost-effective method of onsite nitrogen generation for a wide range of purity and flow requirements. itrogen gas is a staple of the chemical industry. effective, and convenient for chemical processors. Multiple Because it is an inert gas, nitrogen is suitable for a nitrogen technologies and supply modes now exist to meet a Nwide range of applications covering various aspects range of specifications, including purity, usage pattern, por- of chemical manufacturing, processing, handling, and tability, footprint, and power consumption. Choosing among shipping. Due to its low reactivity, nitrogen is an excellent supply options can be a challenge. Onsite nitrogen genera- blanketing and purging gas that can be used to protect valu- tors, such as pressure swing adsorption (PSA) or membrane able products from harmful contaminants. It also enables the systems, can be more cost-effective than traditional cryo- safe storage and use of flammable compounds, and can help genic distillation or stored liquid nitrogen, particularly if an prevent combustible dust explosions. Nitrogen gas can be extremely high purity (e.g., 99.9999%) is not required. used to remove contaminants from process streams through methods such as stripping and sparging. Generating nitrogen gas Because of the widespread and growing use of nitrogen Industrial nitrogen gas can be produced by either in the chemical process industries (CPI), industrial gas com- cryogenic fractional distillation of liquefied air, or separa- panies have been continually improving methods of nitrogen tion of gaseous air using adsorption or permeation. -
Sorption and Activation of Hydrocarbons by Molecular Sieves Johannes a Lercher* and Kulathuiyer Seshant
57 Sorption and activation of hydrocarbons by molecular sieves Johannes A Lercher* and Kulathuiyer Seshant Substantial progress has been made recently in the report of the reactions and catalyst performance is not understanding of sorption and activation of alkanes. This attempted. progress reflects the emergence of new theoretical and experimental results, leading to a more quantitative picture Adsorption of hydrocarbons of the elementary steps involved in the ordering of alkanes Structural and energetic aspects of alkane adsorption in molecular sieves and their chemical interaction with the It is commonly accepted that alkanes are primarily acid site. Conversion of n-alkanes over various zeolites is now bound by dispersive interactions to the molecular sieve well understood to depend mainly upon the concentration walls, independently of the presence or absence of of reactants sorbed. The sorption enthalpy and entropy of Br6nsted or Lewis acids sites (see for example [1°]). these molecules are linearly related and this relationship is These dispersive interactions lead to a generally weak characteristic of a particular molecular sieve (compensation perturbation of the alkane C-H bonds; the perturbation effect). The interfacial chemistry that alkanes and alkenes has been experimentally observed by IR spectroscopy undergo involves ionic species only in their transition state, [Z',3]. whereas the stable intermediates are covalently bound. This leads to a description of the chemical transformations that The energy of interaction (e.g. represented by the heat resemble nucleophilic and electrophilic substitutions. of adsorption) between aikanes and molecular sieves in- creases with the number of carbon atoms of the adsorbate. For molecular sieves that constrain molecule-molecule Addresses interactions, this increase is a linear function of the University of Twente, Faculty of Chemical Technology, PO Box 217, 7500 AE Enschede, The Netherlands number of carbon atoms, for alkanes with similar structure *e-mail: [email protected] (e.g. -
THE SOLUBILITY of GASES in LIQUIDS INTRODUCTION the Solubility Data Project Aims to Make a Comprehensive Search of the Lit- Erat
THE SOLUBILITY OF GASES IN LIQUIDS R. Battino, H. L. Clever and C. L. Young INTRODUCTION The Solubility Data Project aims to make a comprehensive search of the lit erature for data on the solubility of gases, liquids and solids in liquids. Data of suitable accuracy are compiled into data sheets set out in a uni form format. The data for each system are evaluated and where data of suf ficient accuracy are available values recommended and in some cases a smoothing equation suggested to represent the variation of solubility with pressure and/or temperature. A text giving an evaluation and recommended values and the compiled data sheets are pUblished on consecutive pages. DEFINITION OF GAS SOLUBILITY The distinction between vapor-liquid equilibria and the solUbility of gases in liquids is arbitrary. It is generally accepted that the equilibrium set up at 300K between a typical gas such as argon and a liquid such as water is gas liquid solubility whereas the equilibrium set up between hexane and cyclohexane at 350K is an example of vapor-liquid equilibrium. However, the distinction between gas-liquid solUbility and vapor-liquid equilibrium is often not so clear. The equilibria set up between methane and propane above the critical temperature of methane and below the critical temperature of propane may be classed as vapor-liquid equilibrium or as gas-liquid solu bility depending on the particular range of pressure considered and the par ticular worker concerned. The difficulty partly stems from our inability to rigorously distinguish between a gas, a vapor, and a liquid, which has been discussed in numerous textbooks. -
Integrated Testing of a 4-Bed Molecular Sieve and a Temperature-Swing Adsorption Compressor for Closed-Loop Air Revitalization
041CES-299 Integrated Testing of a 4-Bed Molecular Sieve and a Temperature-Swing Adsorption Compressor for Closed-Loop Air Revitalization James C. Knox Marshall Space Flight Center, NASA Lila M. Mulloth, David L. Affleck Science Applications Intl.Corp. Copyright 0 2004 SAE International ABSTRACT ATMOSPHERE REVITALIZATION SUBSYSTEM Accumulation and subsequent compression of carbon As part of the International Space Station (ISS) growth to dioxide that is removed from space cabin are two support six to seven crewmembers, development is important processes involved in a closed-loop air underway of a Sabatier COS Reduction assembly. A revitalization scheme of the International Space Station 4BMS is currently on the ISS Destiny module for removal (ISS). The 4-Bed Molecular Sieve (4BMS) of ISS of metabolic COS. An identical 4BMS is being prepared currently operates in an open loop mode without a for Node 3. These and other elements of the Node 3 compressor. This paper reports the integrated 4BMS and environmental control and life support system (ECLSS) liquid-cooled TSAC testing conducted during the period are shown in Figure 1. Those elements pertaining to this of March 3 to April 18, 2003. The TSAC prototype was paper are described in the following paragraphs. developed at NASA Ames Research Center (ARC)'. The 4BMS was modified to a functionally flight-like pondition Air at NASA Marshall Space Flight Center (MSFC) . Testing was conducted at MSFC. The paper provides details of the TSAC operation at various COS loadings and corresponding performance of CDRA. INTRODUCTION The TSAC is a candidate technology to provide buffering of the carbon dioxide (C02) stream between the 4BMS and the Sabatier components, part of a closed loop atmosphere revitalization system (ARS). -
Dissolved Oxygen in the Blood
Chapter 1 – Dissolved Oxygen in the Blood Say we have a volume of blood, which we’ll represent as a beaker of fluid. Now let’s include oxygen in the gas above the blood (represented by the green circles). The oxygen exerts a certain amount of partial pressure, which is a measure of the concentration of oxygen in the gas (represented by the pink arrows). This pressure causes some of the oxygen to become dissolved in the blood. If we raise the concentration of oxygen in the gas, it will have a higher partial pressure, and consequently more oxygen will become dissolved in the blood. Keep in mind that what we are describing is a dynamic process, with oxygen coming in and out of the blood all the time, in order to maintain a certain concentration of dissolved oxygen. This is known as a) low partial pressure of oxygen b) high partial pressure of oxygen dynamic equilibrium. As you might expect, lowering the oxygen concentration in the gas would lower its partial pressure and a new equilibrium would be established with a lower dissolved oxygen concentration. In fact, the concentration of DISSOLVED oxygen in the blood (the CdO2) is directly proportional to the partial pressure of oxygen (the PO2) in the gas. This is known as Henry's Law. In this equation, the constant of proportionality is called the solubility coefficient of oxygen in blood (aO2). It is equal to 0.0031 mL / mmHg of oxygen / dL of blood. With these units, the dissolved oxygen concentration must be measured in mL / dL of blood, and the partial pressure of oxygen must be measured in mmHg. -
CEE 370 Environmental Engineering Principles Henry's
CEE 370 Lecture #7 9/18/2019 Updated: 18 September 2019 Print version CEE 370 Environmental Engineering Principles Lecture #7 Environmental Chemistry V: Thermodynamics, Henry’s Law, Acids-bases II Reading: Mihelcic & Zimmerman, Chapter 3 Davis & Masten, Chapter 2 Mihelcic, Chapt 3 David Reckhow CEE 370 L#7 1 Henry’s Law Henry's Law states that the amount of a gas that dissolves into a liquid is proportional to the partial pressure that gas exerts on the surface of the liquid. In equation form, that is: C AH = K p A where, CA = concentration of A, [mol/L] or [mg/L] KH = equilibrium constant (often called Henry's Law constant), [mol/L-atm] or [mg/L-atm] pA = partial pressure of A, [atm] David Reckhow CEE 370 L#7 2 Lecture #7 Dave Reckhow 1 CEE 370 Lecture #7 9/18/2019 Henry’s Law Constants Reaction Name Kh, mol/L-atm pKh = -log Kh -2 CO2(g) _ CO2(aq) Carbon 3.41 x 10 1.47 dioxide NH3(g) _ NH3(aq) Ammonia 57.6 -1.76 -1 H2S(g) _ H2S(aq) Hydrogen 1.02 x 10 0.99 sulfide -3 CH4(g) _ CH4(aq) Methane 1.50 x 10 2.82 -3 O2(g) _ O2(aq) Oxygen 1.26 x 10 2.90 David Reckhow CEE 370 L#7 3 Example: Solubility of O2 in Water Background Although the atmosphere we breathe is comprised of approximately 20.9 percent oxygen, oxygen is only slightly soluble in water. In addition, the solubility decreases as the temperature increases.