This document provides an overview of distillation theory and design. It discusses the necessary components, calculations, and graphical method (McCabe-Thiele diagram) to determine the minimum reflux ratio and number of trays for a distillation column. The method involves drawing operating lines on a diagram with the vapor and liquid compositions to intersect the equilibrium curve and determine the minimum reflux ratio. The actual design reflux ratio is typically 20% higher for optimal costs. Stepping lines between the operating lines and equilibrium curve provides the minimum number of trays.
This document provides an overview of distillation theory and design. It discusses the necessary components, calculations, and graphical method (McCabe-Thiele diagram) to determine the minimum reflux ratio and number of trays for a distillation column. The method involves drawing operating lines on a diagram with the vapor and liquid compositions to intersect the equilibrium curve and determine the minimum reflux ratio and number of theoretical trays needed.
Distillation is a method of separating mixtures based on differences in their volatilities through boiling and condensation. Key points:
- It involves heating a mixture to vaporize more volatile components, cooling to condense the vapor into separate products.
- Common uses include separating crude oil, purifying water and air, producing alcoholic beverages.
- Types include simple, fractional, flash, and vacuum distillation. Flash distillation partially vaporizes a liquid through pressure reduction.
- Distillation columns contain internals like trays or packings to facilitate vapor-liquid contact during separation. Fractional distillation uses multiple equilibrium stages for high purity products.
Slides for the eLearning course Separation and purification processes in biorefineries (https://open-learn.xamk.fi) in IMPRESS project (https://www.spire2030.eu/impress).
Section: Distillation
Subject: 2.1 Material balances
Slides for the eLearning course Separation and purification processes in biorefineries (https://open-learn.xamk.fi) in IMPRESS project.
Section: Distillation
Subject: 0.3 Basic concepts of distillation
This document discusses reflux ratios in distillation columns. It defines total, minimum, and optimum reflux ratios. Total reflux uses all overhead vapor as reflux, allowing calculation of minimum required plates. Minimum reflux is the maximum ratio requiring infinite plates for desired separation. Optimum reflux minimizes total costs by balancing fixed costs that decrease with higher reflux against increasing operating costs.
pressure drop calculation in sieve plate distillation columnAli Shaan Ghumman
This document provides a multi-part assignment problem involving distillation column design and analysis. In part 1, the document summarizes the calculation of the number of theoretical plates and feed location for a binary distillation column separating benzene and toluene using the McCabe-Thiele method. The summary finds that the column requires 7 plates with the feed on plate 4. Part 2 involves using the Fenske equation to determine the minimum number of plates and minimum reflux ratio for a pentane-hexane separation. The summary states that the minimum number of plates is 4 and the minimum reflux ratio is 0.9024. Part 3 involves calculations to determine the allowable vapor velocity, column diameter, pressure drop per plate
basics of ponchon savrit method to calculate no. of trays in distillation column and this could be more feasible for those who are willing to study separation processes related to their chemical engineering fields. moreover, if you find difficulty in taking lectures on YouTube, you can just click on this link and just download the slides for its study. as every student in this world in willing to study the basics of chemical engineering, this could be more beneficial for those students. also if your teacher wants any presentation slides on this specific topic, you can just download these slides from the website and can present in a better way to proceed you knowledge and journey of your education.
Packed columns are used for distillation, gas absorption, and liquid-liquid extraction. They have continuous gas-liquid contact through a packed bed, unlike plate columns which have stage-wise contact. Packed columns depend on good liquid and gas distribution, and have lower holdup but higher pressure drop than plate columns. This document provides details on packed column components, design procedures such as selecting packing and determining height, and examples of absorption and stripping processes in packed columns.
This document provides an overview of distillation theory and design. It discusses the necessary components, calculations, and graphical method (McCabe-Thiele diagram) to determine the minimum reflux ratio and number of trays for a distillation column. The method involves drawing operating lines on a diagram with the vapor and liquid compositions to intersect the equilibrium curve and determine the minimum reflux ratio and number of theoretical trays needed.
Distillation is a method of separating mixtures based on differences in their volatilities through boiling and condensation. Key points:
- It involves heating a mixture to vaporize more volatile components, cooling to condense the vapor into separate products.
- Common uses include separating crude oil, purifying water and air, producing alcoholic beverages.
- Types include simple, fractional, flash, and vacuum distillation. Flash distillation partially vaporizes a liquid through pressure reduction.
- Distillation columns contain internals like trays or packings to facilitate vapor-liquid contact during separation. Fractional distillation uses multiple equilibrium stages for high purity products.
Slides for the eLearning course Separation and purification processes in biorefineries (https://open-learn.xamk.fi) in IMPRESS project (https://www.spire2030.eu/impress).
Section: Distillation
Subject: 2.1 Material balances
Slides for the eLearning course Separation and purification processes in biorefineries (https://open-learn.xamk.fi) in IMPRESS project.
Section: Distillation
Subject: 0.3 Basic concepts of distillation
This document discusses reflux ratios in distillation columns. It defines total, minimum, and optimum reflux ratios. Total reflux uses all overhead vapor as reflux, allowing calculation of minimum required plates. Minimum reflux is the maximum ratio requiring infinite plates for desired separation. Optimum reflux minimizes total costs by balancing fixed costs that decrease with higher reflux against increasing operating costs.
pressure drop calculation in sieve plate distillation columnAli Shaan Ghumman
This document provides a multi-part assignment problem involving distillation column design and analysis. In part 1, the document summarizes the calculation of the number of theoretical plates and feed location for a binary distillation column separating benzene and toluene using the McCabe-Thiele method. The summary finds that the column requires 7 plates with the feed on plate 4. Part 2 involves using the Fenske equation to determine the minimum number of plates and minimum reflux ratio for a pentane-hexane separation. The summary states that the minimum number of plates is 4 and the minimum reflux ratio is 0.9024. Part 3 involves calculations to determine the allowable vapor velocity, column diameter, pressure drop per plate
basics of ponchon savrit method to calculate no. of trays in distillation column and this could be more feasible for those who are willing to study separation processes related to their chemical engineering fields. moreover, if you find difficulty in taking lectures on YouTube, you can just click on this link and just download the slides for its study. as every student in this world in willing to study the basics of chemical engineering, this could be more beneficial for those students. also if your teacher wants any presentation slides on this specific topic, you can just download these slides from the website and can present in a better way to proceed you knowledge and journey of your education.
Packed columns are used for distillation, gas absorption, and liquid-liquid extraction. They have continuous gas-liquid contact through a packed bed, unlike plate columns which have stage-wise contact. Packed columns depend on good liquid and gas distribution, and have lower holdup but higher pressure drop than plate columns. This document provides details on packed column components, design procedures such as selecting packing and determining height, and examples of absorption and stripping processes in packed columns.
This document provides an overview of various distillation techniques including:
- Flash distillation which separates mixtures at steady state based on enthalpy and concentration.
- Steam distillation which uses the immiscibility of a substance and water to separate traces of non-volatile impurities.
- Batch and continuous multistage fractionation which separate binary mixtures using distillation columns, with concepts like relative volatility and reflux ratios.
- McCabe-Thiele and Ponchon-Savarit methods which graphically analyze multistage distillation.
- Azeotropic distillation, extractive distillation, and reactive distillation which use additional techniques like entrainers or integrated reactions to separate mixtures.
The document discusses the McCabe-Thiele design method for distillation column design using vapor-liquid equilibrium (VLE) data. It explains that the McCabe-Thiele method uses a graphical approach to determine the theoretical number of stages required for a binary separation based on the VLE plot. Operating lines are drawn on the VLE diagram to define the mass balance relationships between the liquid and vapor phases. The operating line for the rectification section is constructed by drawing a line with slope R/(R+1) from the desired top product composition point, where R is the reflux ratio. The operating line for the stripping section has a slope of Ls/Vs, where Ls and Vs are the liquid and
An overview of distillation column design concepts and major design considerations. Explains distillation column design concepts, what you would provide to a professional distillation column designer, and what you can expect back from a distillation system design firm. To speak with an engineer about your distillation column project, call EPIC at 314-207-4250.
This document discusses the McCabe-Thiele method for designing binary distillation columns. The method uses vapor-liquid equilibrium (VLE) data to graphically determine the theoretical number of stages required for separation. Operating lines are drawn on the VLE diagram based on the desired compositions of top and bottom products. Where these lines intersect represents equilibrium stages. The number of intersections equals the number of theoretical stages. Additional trays are needed based on tray efficiency. The feed point can also be determined from its vapor-liquid condition. Overall column design requires considering additional factors like tray spacing, diameter, and heating/cooling duties through an iterative process.
Gaurvansh Sharma presented on the design of distillation columns. He discussed the different types of distillation including simple, steam, vacuum, and fractional distillation. He explained the components and internals of distillation columns, including trays, packings, condensers, reflux drums, and reboilers. Reboilers are heat exchangers that boil the liquid from the bottom of the column to generate vapors to drive the distillation separation. Sharma discussed factors that affect column performance and thanked the audience.
The basic requirements of a plate contacting stage are that it should:
Provide good vapour-liquid contact.
Provide sufficient liquid hold-up for good mass transfer (high efficiency).
Have sufficient area and spacing to keep the entrainment and pressure drop withinacceptable limits.
Have sufficient downcomer area for the liquid to flow freely from plate to plate
Slides for the eLearning course Separation and purification processes in biorefineries (https://open-learn.xamk.fi) in IMPRESS project (https://www.spire2030.eu/impress).
Subject: 2.4 Plate efficiencies.
Distillation is one of unit operation which is uses for separation of two or more liquids which have difference in boiling points. Basic theory and calculation of Distillation which will help to understand Distillation and stage calculation. it will be helpful for students who are studying chemical engineering and fresh engineers in chemical process industries.
Distillation is a method to separate mixtures based on differences in volatility. It involves boiling the mixture and condensing the vapor produced. Simple distillation produces an impure distillate while fractional distillation uses a fractionating column for multiple vaporization-condensation cycles, allowing better separation. Vacuum distillation uses reduced pressure for distillation at lower temperatures to prevent degradation. Batch distillation processes mixtures in batches while continuous distillation constantly feeds and removes fractions.
This document discusses multistage separation processes and provides an example problem. It introduces the Ponchon Savarit method for determining the minimum number of theoretical plates in a distillation column. This includes calculating enthalpy and equilibrium values, determining flow rates of distillate and bottoms, and using graphs to find the minimum reflux ratio. For the example of separating an ethanol-water mixture, the number of plates is calculated as 14 when using a reflux ratio of 1.25 times the minimum, and as 10 plates when using a condenser duty of 106 BTU/h. The reboiler duty is also determined.
Heat exchangers transfer heat from one medium to another. They are classified by flow configuration and construction. Key flow configurations are parallel, counter, and cross flow. Main construction types are shell and tube, and plate heat exchangers. Heat transfer is calculated using methods like log mean temperature difference (LMTD) and number of transfer units (NTU). Standards like TEMA provide guidelines for shell and tube heat exchanger design and components.
Evaporators are used to reduce the volume of a liquid by boiling it. This concentrates the liquid and removes solvents. There are different types of evaporators that use heat exchange and decreasing pressure between effects to boil liquids. Key components include a heat exchanger, vacuum system, vapor separator and condenser. Process factors like material properties, temperatures, and pressures must be considered during evaporator operation.
Reactive distillation
LeChatelier’s law
conventional process
mtbe production using Reactive distillation
various contact devices used for Reactive distillation
advantages of Reactive distillation
disadvantages of Reactive distillation
application of Reactive distillation
A reboiler is a heat exchanger that provides heat to the bottom of a distillation column. There are several types of reboilers including kettle reboilers, thermosyphon reboilers, fired reboilers, and forced circulation reboilers. Kettle reboilers are simple devices where steam flows through tubes in a shell to heat liquid in the shell. Thermosyphon reboilers use density differences to circulate liquid without pumps. Fired reboilers use combustion to heat liquid circulating through tubes. Forced circulation reboilers use pumps to circulate liquid through shell and tube heat exchangers.
This document describes a study for the production of ethylene glycol through the hydrolysis of ethylene oxide with water. It discusses the significance of ethylene glycol and its uses in various industries such as antifreeze and polyester fibers. The most common manufacturing method is described as the hydrolysis of ethylene oxide through a ring-opening reaction. A flow diagram shows the process which involves hydrating ethylene oxide in a reactor, evaporating the water-glycol mixture in multiple stages, stripping remaining water and purifying through distillation. The study aims to design a process capable of producing 100,000 tons per year of ethylene glycol.
This document provides an overview of crystallization processes. It discusses how crystals form from solutions or melts via nucleation and growth. Primary and secondary nucleation are described. Mass transfer and population balance theories are used to model crystal growth rates and size distributions. The document outlines how continuous crystallizers like MSMPR systems operate and how residence time affects crystal size distribution. Methods for controlling crystal size like double draw-off, fines removal, and classified product removal are also summarized.
The McCabe-Thiele method is a graphical technique for determining the minimum number of stages required for distillation. It involves plotting the equilibrium relationship between liquid and vapor phases on a diagram and constructing operating lines to represent the mass balances in the rectifying and stripping sections. Intersections between the lines indicate the number of ideal stages. The method was developed in 1925 and remains useful for preliminary column design. Key considerations include the feed composition and enthalpy, reflux ratio, and use of partial condensers or reboilers.
- This document describes absorption and stripping processes using packed columns and graphical methods.
- It discusses operating lines, height of transfer units (HOG), number of transfer units (NOG), and how to calculate the height equivalent of a theoretical plate (HETP) for a packed column given mass transfer coefficients, flow rates, and equilibrium data.
- An example is provided to calculate the HETP for a specific packed column based on the mass transfer coefficients, flow rates, and equilibrium constant given.
This document presents information about fluidization and was prepared by 5 students. It defines fluidization as a process where solids are made to behave like fluids by passing gas or liquid upwards. Fluidization is widely used in industries for operations like transportation, heating, mixing and chemical reactions using catalysts. The document discusses fluidization regimes from fixed beds to entrained beds as gas velocity increases. It also describes Geldart's classification of powders and common applications of fluidization like fluid catalytic cracking in petroleum industry.
The document discusses the basics of distillation column design. It explains that column design begins with building a model of how the chemicals will separate based on their properties like vapor pressure and boiling point. The model is used to identify the minimum number of theoretical stages or trays needed for effective separation. Key design considerations include parameters like flood ratio, weeping point, efficiency, reflux ratio, and HETP. The document also outlines the basic components of a distillation column like the condenser, reboiler, and trays or packing material. It notes the inputs needed from the client and outputs provided by an expert column designer.
This document provides an overview of various distillation techniques including:
- Flash distillation which separates mixtures at steady state based on enthalpy and concentration.
- Steam distillation which uses the immiscibility of a substance and water to separate traces of non-volatile impurities.
- Batch and continuous multistage fractionation which separate binary mixtures using distillation columns, with concepts like relative volatility and reflux ratios.
- McCabe-Thiele and Ponchon-Savarit methods which graphically analyze multistage distillation.
- Azeotropic distillation, extractive distillation, and reactive distillation which use additional techniques like entrainers or integrated reactions to separate mixtures.
The document discusses the McCabe-Thiele design method for distillation column design using vapor-liquid equilibrium (VLE) data. It explains that the McCabe-Thiele method uses a graphical approach to determine the theoretical number of stages required for a binary separation based on the VLE plot. Operating lines are drawn on the VLE diagram to define the mass balance relationships between the liquid and vapor phases. The operating line for the rectification section is constructed by drawing a line with slope R/(R+1) from the desired top product composition point, where R is the reflux ratio. The operating line for the stripping section has a slope of Ls/Vs, where Ls and Vs are the liquid and
An overview of distillation column design concepts and major design considerations. Explains distillation column design concepts, what you would provide to a professional distillation column designer, and what you can expect back from a distillation system design firm. To speak with an engineer about your distillation column project, call EPIC at 314-207-4250.
This document discusses the McCabe-Thiele method for designing binary distillation columns. The method uses vapor-liquid equilibrium (VLE) data to graphically determine the theoretical number of stages required for separation. Operating lines are drawn on the VLE diagram based on the desired compositions of top and bottom products. Where these lines intersect represents equilibrium stages. The number of intersections equals the number of theoretical stages. Additional trays are needed based on tray efficiency. The feed point can also be determined from its vapor-liquid condition. Overall column design requires considering additional factors like tray spacing, diameter, and heating/cooling duties through an iterative process.
Gaurvansh Sharma presented on the design of distillation columns. He discussed the different types of distillation including simple, steam, vacuum, and fractional distillation. He explained the components and internals of distillation columns, including trays, packings, condensers, reflux drums, and reboilers. Reboilers are heat exchangers that boil the liquid from the bottom of the column to generate vapors to drive the distillation separation. Sharma discussed factors that affect column performance and thanked the audience.
The basic requirements of a plate contacting stage are that it should:
Provide good vapour-liquid contact.
Provide sufficient liquid hold-up for good mass transfer (high efficiency).
Have sufficient area and spacing to keep the entrainment and pressure drop withinacceptable limits.
Have sufficient downcomer area for the liquid to flow freely from plate to plate
Slides for the eLearning course Separation and purification processes in biorefineries (https://open-learn.xamk.fi) in IMPRESS project (https://www.spire2030.eu/impress).
Subject: 2.4 Plate efficiencies.
Distillation is one of unit operation which is uses for separation of two or more liquids which have difference in boiling points. Basic theory and calculation of Distillation which will help to understand Distillation and stage calculation. it will be helpful for students who are studying chemical engineering and fresh engineers in chemical process industries.
Distillation is a method to separate mixtures based on differences in volatility. It involves boiling the mixture and condensing the vapor produced. Simple distillation produces an impure distillate while fractional distillation uses a fractionating column for multiple vaporization-condensation cycles, allowing better separation. Vacuum distillation uses reduced pressure for distillation at lower temperatures to prevent degradation. Batch distillation processes mixtures in batches while continuous distillation constantly feeds and removes fractions.
This document discusses multistage separation processes and provides an example problem. It introduces the Ponchon Savarit method for determining the minimum number of theoretical plates in a distillation column. This includes calculating enthalpy and equilibrium values, determining flow rates of distillate and bottoms, and using graphs to find the minimum reflux ratio. For the example of separating an ethanol-water mixture, the number of plates is calculated as 14 when using a reflux ratio of 1.25 times the minimum, and as 10 plates when using a condenser duty of 106 BTU/h. The reboiler duty is also determined.
Heat exchangers transfer heat from one medium to another. They are classified by flow configuration and construction. Key flow configurations are parallel, counter, and cross flow. Main construction types are shell and tube, and plate heat exchangers. Heat transfer is calculated using methods like log mean temperature difference (LMTD) and number of transfer units (NTU). Standards like TEMA provide guidelines for shell and tube heat exchanger design and components.
Evaporators are used to reduce the volume of a liquid by boiling it. This concentrates the liquid and removes solvents. There are different types of evaporators that use heat exchange and decreasing pressure between effects to boil liquids. Key components include a heat exchanger, vacuum system, vapor separator and condenser. Process factors like material properties, temperatures, and pressures must be considered during evaporator operation.
Reactive distillation
LeChatelier’s law
conventional process
mtbe production using Reactive distillation
various contact devices used for Reactive distillation
advantages of Reactive distillation
disadvantages of Reactive distillation
application of Reactive distillation
A reboiler is a heat exchanger that provides heat to the bottom of a distillation column. There are several types of reboilers including kettle reboilers, thermosyphon reboilers, fired reboilers, and forced circulation reboilers. Kettle reboilers are simple devices where steam flows through tubes in a shell to heat liquid in the shell. Thermosyphon reboilers use density differences to circulate liquid without pumps. Fired reboilers use combustion to heat liquid circulating through tubes. Forced circulation reboilers use pumps to circulate liquid through shell and tube heat exchangers.
This document describes a study for the production of ethylene glycol through the hydrolysis of ethylene oxide with water. It discusses the significance of ethylene glycol and its uses in various industries such as antifreeze and polyester fibers. The most common manufacturing method is described as the hydrolysis of ethylene oxide through a ring-opening reaction. A flow diagram shows the process which involves hydrating ethylene oxide in a reactor, evaporating the water-glycol mixture in multiple stages, stripping remaining water and purifying through distillation. The study aims to design a process capable of producing 100,000 tons per year of ethylene glycol.
This document provides an overview of crystallization processes. It discusses how crystals form from solutions or melts via nucleation and growth. Primary and secondary nucleation are described. Mass transfer and population balance theories are used to model crystal growth rates and size distributions. The document outlines how continuous crystallizers like MSMPR systems operate and how residence time affects crystal size distribution. Methods for controlling crystal size like double draw-off, fines removal, and classified product removal are also summarized.
The McCabe-Thiele method is a graphical technique for determining the minimum number of stages required for distillation. It involves plotting the equilibrium relationship between liquid and vapor phases on a diagram and constructing operating lines to represent the mass balances in the rectifying and stripping sections. Intersections between the lines indicate the number of ideal stages. The method was developed in 1925 and remains useful for preliminary column design. Key considerations include the feed composition and enthalpy, reflux ratio, and use of partial condensers or reboilers.
- This document describes absorption and stripping processes using packed columns and graphical methods.
- It discusses operating lines, height of transfer units (HOG), number of transfer units (NOG), and how to calculate the height equivalent of a theoretical plate (HETP) for a packed column given mass transfer coefficients, flow rates, and equilibrium data.
- An example is provided to calculate the HETP for a specific packed column based on the mass transfer coefficients, flow rates, and equilibrium constant given.
This document presents information about fluidization and was prepared by 5 students. It defines fluidization as a process where solids are made to behave like fluids by passing gas or liquid upwards. Fluidization is widely used in industries for operations like transportation, heating, mixing and chemical reactions using catalysts. The document discusses fluidization regimes from fixed beds to entrained beds as gas velocity increases. It also describes Geldart's classification of powders and common applications of fluidization like fluid catalytic cracking in petroleum industry.
The document discusses the basics of distillation column design. It explains that column design begins with building a model of how the chemicals will separate based on their properties like vapor pressure and boiling point. The model is used to identify the minimum number of theoretical stages or trays needed for effective separation. Key design considerations include parameters like flood ratio, weeping point, efficiency, reflux ratio, and HETP. The document also outlines the basic components of a distillation column like the condenser, reboiler, and trays or packing material. It notes the inputs needed from the client and outputs provided by an expert column designer.
This document summarizes various distillation techniques including differential distillation, flash vaporization, continuous rectification, and determining the ideal number of plates. It discusses mass balances, operating lines, reflux ratios, and how changing the number of plates and reflux ratio influences distillation column design and performance. Key aspects covered include equilibrium relationships, material flowing between plates, determining flow rates, and using diagrams to analyze fractionation.
The document discusses key concepts in multicomponent distillation including:
- Key components are chosen to indicate separation and are always distributed between products.
- The Fenske equation is used to determine minimum number of stages assuming constant relative volatility, while the Underwood method determines minimum reflux ratio.
- The Gilliland correlation estimates actual number of stages given operating reflux from minimum values.
This document describes an experiment to determine the efficiency of a continuous plate distillation column. It provides background on distillation column design and efficiency calculations using concepts like theoretical plates, reflux ratio, and Fenske's method. The experiment involves running a methanol-water mixture through a distillation column at total reflux to establish equilibrium. Samples are taken from the overhead and their compositions are measured using a refractometer and calibration curve. The number of theoretical plates is then calculated using the compositions and Fenske's method. This is compared to the actual number of plates in the column to determine the efficiency. Key steps include establishing a calibration curve, collecting samples at various reflux rates, measuring compositions, and performing efficiency calculations.
Distillation is a common separation technique that relies on differences in boiling points. It can be energy intensive and account for over 50% of operating costs. There are various types of distillation columns, including batch vs continuous, binary vs multi-component, and tray vs packed columns. Key components include a shell, internals, reboiler, condenser, and reflux drum. McCabe-Thiele design uses vapor-liquid equilibrium data to determine the theoretical number of stages needed for separation.
This document discusses the recycle structure design level for a chemical process. It addresses questions like how many reactor systems and recycle streams are required. Using examples, it explains how to determine the number of recycle streams based on boiling points of components leaving the reactor. The document also discusses whether excess reactants should be used, if a gas compressor is needed, and how to determine the reactor heat requirements and temperature changes.
L09-Separations and Column Simulation.pptxKAhmedRehman
This document provides an overview of distillation columns and separation train design. It discusses different types of distillation columns including plate columns with bubble cap trays and sieve trays, and packed columns. It also covers concepts like equilibrium lines, operating lines, minimum reflux ratio, and McCabe-Thiele diagrams. The document discusses methods for determining the number of columns needed, possible sequences, and how to evaluate sequences using the marginal vapor rate method. Finally, it provides heuristics for sequencing separation points in a distillation train.
Gas absorption is a process used to separate gases by contacting a gas mixture with a liquid solvent. The key principles are the solubility of the absorbed gas and the rate of mass transfer as the gas dissolves into the liquid. Absorption is usually carried out counter-currently in vertical columns. The solvent is fed at the top while the gas enters at the bottom, allowing the absorbed substances to be washed out in the downward flowing liquid. Proper selection of solvent considers factors like gas solubility, volatility, cost, and viscosity. Rate of absorption is determined by volumetric mass transfer coefficients, which can be calculated from operating line and equilibrium curve diagrams.
10 synthesis of reaction separation system lec 10 homogenous separationayimsevenfold
This document discusses guidelines for sequencing separation systems for homogenous mixtures. It recommends selecting the sequence that requires the least energy, typically determined by calculating the minimum vapor flow for each sequence using the Underwood equation. An example applies this method to evaluate different distillation sequences for separating a 5-component mixture, identifying the sequence with the lowest total minimum vapor flow as the preferred option.
Combustion tutorial ( Eddy Break up Model) , CFDA.S.M. Abdul Hye
This document provides a tutorial for using STAR-CCM+ to simulate three combustion models: an idealized CAN gas turbine combustion chamber, a flame tube, and methane on platinum. It describes setting up simulations for each model, including importing geometries, defining materials and reactions, setting boundary conditions and solver parameters, and visualizing results. Specific steps are outlined for a simulation of propane combustion in a CAN chamber using an eddy break-up model, including generating a PPDF table and specifying initial conditions and stopping criteria.
The document discusses heat engines and power cycles. It introduces the concept of using a working fluid to absorb heat from a reservoir, produce work, and reject heat to a cold reservoir. The Carnot cycle is described as the most efficient cycle, involving four processes: two reversible, isothermal processes where heat is absorbed and rejected, and two reversible, adiabatic (isentropic) processes where expansion and compression occur. An example problem is presented on calculating properties of the working fluid in a Carnot cycle using a T-S diagram, tables of property data, and energy balances around the system components.
4 modeling and control of distillation column in a petroleum processnazir1988
This document describes the modeling and simulation of a condensate distillation column in a petroleum process. It presents a calculation procedure to model the column based on an energy balance structure using reflux rate and boilup rate as inputs to control distillate purity and bottom product impurity. A nonlinear dynamic model of the column is developed and simulated in MATLAB. The simulation shows the column can maintain product quality under normal operations but quality decreases with disturbances like changes in feed rate. A reduced-order linear model is then developed for use in model-reference adaptive control to improve disturbance rejection.
The document discusses multistage separation processes and provides an example problem. The example problem is to separate a benzene-toluene mixture using distillation. It is determined that:
1) The column requires a total of 7 theoretical plates, with 4 in the top section and 3 in the bottom section including the reboiler.
2) The feed should enter between the 3rd and 4th plates from the top.
3) The compositions of the vapor and liquid phases are calculated for each plate.
The document describes continuous flash distillation. Flash distillation involves partially vaporizing a liquid mixture, allowing the vapor and liquid to reach equilibrium, and then withdrawing them separately. Material balances are used to model flash distillation. The flash distillation process is commonly used in the petroleum industry to separate petroleum fractions by heating the fluid and "flashing" it into an overheated vapor stream and residual liquid stream.
The document discusses the design of a separation system for a chemical process. It begins by outlining the general structure of a separation system, which can include a liquid separation system, vapor recovery system, or both depending on whether the reactor effluent is liquid, gas, or two-phase.
It then discusses methods for approximating flash calculations to determine the phase split from a reactor. The document also provides heuristics for deciding the location of a vapor recovery system and types of vapor recovery systems.
Finally, it outlines the key decisions that must be made in designing the liquid separation system, including how to remove light ends, where to send the light ends, whether to recycle or split azeotropes
This document summarizes an experiment using continuous rectification to purify an ethanol solution via distillation. The Smoker-Rose method was used to measure distillate composition at different reflux ratios, showing higher ratios produced higher ethanol composition. This indicates the Smoker-Rose method can adequately estimate distillate composition. The document also provides background on distillation and batch distillation, and describes the theory used to determine the minimum reflux ratio and apply the Smoker-Rose method to approximate distillate composition.
Batch distillation employing cyclic rectification and stripping operationsISA Interchange
Several strategies have been proposed to increase the operating efficiency of batch distillation. In this study, conventional batch rectification and inverted batch stripping are used cyclically to promote high product flow rates for a binary fractionation. Process controls are implemented to maintain constant product purity specifications by varying the slope of the operating line. While rectifying, the light component is removed as distillate, concentrating the heavy component in the reboiler. As a result, the distillate rate decreases with time. The column is then changed from rectification to stripping modes, and the heavy component is removed as bottoms product, concentrating the light component in the distillate drum. This causes the bottoms rate to diminish with time, and the column is once again converted back to rectifying mode. Cyclic operation, transitioning from batch rectifying to stripping back to rectifying, continues until all of the initial charge is fractionated or is combined with a new charge. The fractionation of ethanol and 1-propanol using the proposed operating strategy is shown to provide several advantages including energy and time savings when compared to conventional batch or inverted batch distillation alone.
This document provides an overview of gas absorption processes. It discusses the basic principles of absorption where a gas is contacted with a liquid to selectively dissolve components from the gas to the liquid. Two main types of absorption processes are described: physical and chemical. Common equipment used for absorption include tray towers, packed columns, spray towers, and bubble columns. Tray towers and packed columns are the focus. The document outlines general design considerations and provides details on the multi-contact stage graphical equilibrium method for calculating the number of theoretical plates in a tray tower.
This document provides an overview of gas absorption processes. It discusses the basic principles of absorption where a gas is contacted with a liquid to selectively dissolve components from the gas to the liquid. Two main types of absorption processes are described: physical and chemical. Common equipment used for absorption include tray towers, packed columns, spray towers, and bubble columns. Tray towers and packed columns are the focus. The document outlines general design considerations and provides details on the multi-contact stage graphical equilibrium method for calculating the number of theoretical plates in a tray tower.
DEEP LEARNING FOR SMART GRID INTRUSION DETECTION: A HYBRID CNN-LSTM-BASED MODELgerogepatton
As digital technology becomes more deeply embedded in power systems, protecting the communication
networks of Smart Grids (SG) has emerged as a critical concern. Distributed Network Protocol 3 (DNP3)
represents a multi-tiered application layer protocol extensively utilized in Supervisory Control and Data
Acquisition (SCADA)-based smart grids to facilitate real-time data gathering and control functionalities.
Robust Intrusion Detection Systems (IDS) are necessary for early threat detection and mitigation because
of the interconnection of these networks, which makes them vulnerable to a variety of cyberattacks. To
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distillation design.pdf
1. Distillation
Senior Design CHE 396
Andreas Linninger
Innovative Solutions
Michael Redel
Alycia Novoa
Tanya Goldina
Michelle Englert
2. CHE-396 Senior Design (Distillation)
2
Table of Contents
Introduction 3
Flowsheet 4
Limitations 5
Applicability 6
Theory 7
Case Study___________________________________________________24
Alternatives 288
References 309
3. CHE-396 Senior Design (Distillation)
3
Introduction
This report examines the distillation process. This will enable the reader to understand the
necessary components along with distillation calculations. Distillation is a process that
separates two or more components into an overhead distillate and bottoms. The bottoms
product is almost exclusively liquid, while the distillate may be liquid or a vapor or both.
The separation process requires three things. First, a second phase must be formed so that
both liquid and vapor phases are present and can contact each other on each stage within
a separation column. Secondly, the components have different volatilities so that they
will partition between the two phases to different extent. Lastly, the two phases can be
separated by gravity or other mechanical means. Distillation differs from absorption and
stripping in that the second phase is created by thermal means (Seader, 1998).
4. CHE-396 Senior Design (Distillation)
4
Flowsheet
The distillation column contains one feed stream and two product streams. The feed
contains a mole percent of the light component, ZF. The product stream exiting the top
has a composition of XD of the light component. The product stream leaving the bottom
contains a composition of Xb of the light component. The column is broken in two
sections. The top section is referred to as the rectifying section. The bottom section is
known as the stripping section.
The top product stream passes through a total condenser. This effectively condenses all of
the vapor distillate to liquid. The bottom product stream uses a partial reboiler. This
allows for the input of energy into our column.
5. CHE-396 Senior Design (Distillation)
5
Limitations
• Azeotropes: An azeotrope is a liquid mixture which when vaporized produces
the same composition as the liquid. If the mixture is azeotropic, then more
advanced types of separation must be considered. More information on
azeotropes maybe found in Douglas, Section 7.3.
• Solids: If the material to be separated is high in solids, or contains tars or
resins that could plug or foul a continuous unit, then a batch separation should
be considered (Perry’
s, 1997).
• Optimum Pressure (King, 1980):
1. Vacuum operation: Use of a vacuum should be considered for heat-
sensitive compounds or polymerizable materials. Vacuum is usually not
used unless required, e.g., a low bottoms temperature is needed to avoid
thermal decomposition.
2. Distillation column is above atmospheric pressure: Column shell should
be thicker to withstand pressure of the column.
3. If the column pressure required to accomplish overhead condensation with
cooling water is less than 250 lb/in
2
, then the column pressure should give
an average temperature driving force of 5-15*C in the overhead
condenser.
4. If the column pressure required accomplishing overhead condensation
with cooling water is greater than 250 lb/in2
, then consider an alternative
of using a refrigerant on the overhead and running the column at a lower
pressure.
6. CHE-396 Senior Design (Distillation)
6
• Optimum Temperature Differences in Reboilers and Condensers (King,
1980):
1. Reboiler temperatures should be kept low enough to avoid bottoms
degradation and/or fouling.
2. Common temperature differences used for heat exchange across reboilers
and condensers are shown in the following table:
Temp, K
Condenser:
Refrigeration 3-10
Cooling Water 6-20
Pressurized Fluid 10-20
Boiling Water 20-40
Air 20-50
Reboiler:
Process Fluid 10-20
Steam 10-60
Hot Oil 20-60
Applicability
• Distillation is the least expensive means of separating mixtures of liquids.
• If relative volatilities of components is less than 1.1, distillation becomes very
expensive (Douglas, 1988) and extraction or reactive distillation should be
considered.
7. CHE-396 Senior Design (Distillation)
7
Theory
Section 1. Graphical Determination of a Distillation Column Design
Step 1. Determine Process Operation Variables
• Assumed feed rate, composition, purity of distillate and bottoms, and the quality of
the feed are known.
• Perform overall material and component balances to determine the compositions of
the distillate and bottoms.
F*ZF=XD*D+XB*B (1)
F=D+B (2)
where
F Feed rate of input stream
ZF Composition of light component in feed
XD *Mole Fraction of light in distillate
XB *Mole Fraction of light in Bottom
D Total distillate amount
B Total bottom amount
*If more than two components, these values are the light-key and heavy-key component.
Step 2. Determine the Minimum Reflux Ratio
This graphical approach is determined using the McCabe-Thiele Method for binary
mixtures. The ratio of reflux flow to distillate flow is called the reflux ratio.
8. CHE-396 Senior Design (Distillation)
8
Assumptions
The following assumptions are implied when using this method (McCabe,
1993):
a. Constant Molal Overflow. The molar flow rates of the vapor and
liquid are nearly constant in each section of the column. This also
ensures the operating lines are straight lines.
b. Heat Effects are negligible. For example, heat losses to and from
the column are small and neglected.
c. For every mole of vapor condensed, another mole of liquid is
vaporized.
d. The liquid and vapor leaving the tray is in equilibrium with the
vapor and liquid entering the tray.
Procedure
If an equilibrium curve is not given, draw a y-x diagram (y representing the vapor
phase and x the liquid). The equilibrium curve can be obtained by relating the
relative volatility to the composition of the liquid:
y = α*x/(1+x(α-1)) (4)
This shows the bubble-point and dew point of a binary mixture at constant
pressure. An equilibrium line describes the compositions of the liquid and vapor
in equilibrium at a fixed pressure. The equilibrium line crossing the forty-five
degree line is an indication of an azeotropic mixture. An azeotrope is a liquid
mixture which when vaporized produces the same composition as the liquid. If
the mixture is azeotropic, then more advanced types of separation must be
considered.
9. CHE-396 Senior Design (Distillation)
9
• Forty Five Degree Line
1. Draw the diagonal line connecting the points (0.0,0.0) to (1.0,1.0).
This is your forty-five degree line.
• Feed Line (q-Line)
2. The feed line can be constructed by locating the point on the forty-
five degree line that corresponds to the feed composition. This
point can be extended with a slope ofq/(q-1) where q is the feed
quality. The feed line can be directly plotted through the following
equation:
y=q/(q-1)X - ZF/(q-1) (5)
• Upper Operating Line
3. Draw the operating line for the enriching section. First find the
desired top product composition (on the x-axis) and locate the
corresponding point on the forty-five degree line. Connect this
point to the point where the equilibrium cure and the feed line
10. CHE-396 Senior Design (Distillation)
10
intersect. This is the upper operating line. The y intercept of this
line is equal toXD/(R+1). The following equation can be used to
determine the minimum reflux:
Rmin=(XD/yintercept ) – 1 (6)
• Lower Operating Line
4. Draw the operating line for the stripping section. First find the
desired bottom product composition (on the x-axis) and locate the
corresponding point on the forty-five degree line. Draw a line from
this point to the intersection of the equilibrium curve and the feed
line. This is your lower operating line. The slope of this line is
equal to (Vbmin+1)/Vbmin where Vb is the boilup ratio. The
boilup ratio is the fractional amount of liquid that is boiled back
into the column to the amount of liquid leaving.
Step 3. Choose Actual Reflux Ratio:
As the reflux ratio increases, the number of trays and thus the capital cost of the column
decreases. However, as a trade-off, an increase in reflux ratio will also increase the vapor
rate within the tower, thus increasing expenses such as condensers and reboilers (4).
Most columns are designed to operate between 1.2 and 1.5 times the minimum reflux
ratio because this is approximately the region of minimum operating cost. Therefore,
based on first estimates, the operating reflux ratio is equated so that (Douglas, 1988):
Ractual =Rmin* 1.2 (7)
11. CHE-396 Senior Design (Distillation)
11
Step 4. Determine the Minimum Number of Trays
• Upper/Lower Operating Line at Actual Reflux
1. Redraw the upper and lower operating line using the actual reflux ratio. Plot the
point XD/(R+1) and draw a line to the XD. The equation of the upper operating line
is:
y=(R/R+1)*X+XD/(R+1) (8)
The equation for the lower operating line can be drawn by connecting the X
B to
the intersection of the feed line and the upper operating line. The equation of the
lower operating line is:
y=((VB+1)/VB)*X+XB/VB (9)
• Determine Number of Trays
2. Starting from composition of the distillate, a horizontal line is drawn to the
equilibrium curve. This line demonstrates the first tray.
3. From the previous intersection, drop vertically until the upper operating line is
obtained. Follow step two to determine next tray.
12. CHE-396 Senior Design (Distillation)
12
4. Continue stepping until the liquid composition ends equals the desired bottom
composition.
5. The total number of steps is equal to the theoretical number of trays.
6. When high conversions are desired, the stepping method may cause difficulties. In
these cases the Kremser equation should be used.
(10)
where
N Number of trays in unreadable region
m Slope of the line in unreadable region
V/L R/(R+1)
yin Conveniently chosen point below unreadable region
yout XD for rectifying section
ye,out m*XD+b (where b is the y intercept of new equil. line)
( )
( )
+
−
−
−
=
L
V
m
ln
L
V
m
y
y
y
y
*
L
V
m
1
ln
N
out
,
e
out
out
,
e
in
13. CHE-396 Senior Design (Distillation)
13
Step 5. Determine Actual Number of Trays
This is determined by taking the quotient of the number of theoretical trays to the tray
efficiency. Typical values for tray efficiency range from 0.5 to 0.7 (Douglas, 1988).
These values depend on the type of trays being used, as well as the internal liquid and
vapor flow rates.
Nactual = Ntheory /ε (11)
Step 6. Principal Dimensions of the Column (Diameter/Height):
• A design guideline that should be used is that the height of the column should
not be higher than 175 feet.
• Height-to-diameter ratio should be less than 20 to 30.
• Packed towers are used when the column has a small diameter (1.5 ft or less)
or area (1.77 ft2
or less) rather than plate towers.
• Either plate or packed towers may be used when the column diameter is
between 1.5-4.5 ft (or area, 1.77- 15.9 ft2
).
• If the tower is higher than 190 ft, then a design with smaller tray spacing
should be considered (Douglas, 1988).
The tower height can be related to the number of trays in the column. The following
formula assumes that a spacing of two feet between trays will be sufficient including
additional five to ten feet at both ends of the tower. This includes a fifteen percent excess
allowance of space (Douglas, 1988).
Htower = 2.3 Nactual (12)
14. CHE-396 Senior Design (Distillation)
14
Before we can determine the tower diameter, we need to determine the vapor velocity.
The vapor velocity can be derived from the flooding velocity. To limit our column from
flooding, we choose a velocity 50-80 percent of flooding velocity (Douglas, 1988):
(13)
where
V Vapor Velocity
ρG Density of the mixture
The diameter of the tower is relatively insensitive to changes in operating temperature or
pressure. The main determinant of the diameter is the vapor velocity. The desired vapor
velocity is dependent on the limitations of undesired column flooding.
(14)
where
DT Diameter of tower
V Vapor velocity
MG Molecular weight of gas
ρm Molar density
G
2
.
1
V
ρ
=
25
.
0
m
G
T
M
*
V
0164
.
D
ρ
=
15. CHE-396 Senior Design (Distillation)
15
Section 2. Analytically Determining the Specifications for a Distillation Column
Step 1. Determine Process Operation Variables
• Assumed feed rate, composition, purity of distillate and bottoms, and the quality of
the feed are known.
• Perform overall material and component balances to determine the compositions of
the distillate and bottoms.
Step 2. Determine the Minimum Reflux Ratio
• Underwood Equation
The Underwood equation approximates the minimum reflux ratio (Douglas, 1988). The
following equation can be used for multi-component systems with constant relative
volatility. Relating mass balances and VLE equations, the following equation was
derived for whichφcan be calculated.
F*(1-q)= ∑ ((αi * zi)/ (αi -φ
)) (15)
where
F Feed
q Feed quality
αi Relative Volatility
zi Composition of component (i) in Feed
Through the previous expression, φcan be obtained in a polynomial expression. This
expression can be used to solve forφ
. Only the φthat falls between the relative
volatilities of the components should be considered. Theφcan be used to obtain the
minimum amount of vapor (Vmin):
Vmin = ∑ (αi * Dxi)/ (αi -φ
)) (16)
16. CHE-396 Senior Design (Distillation)
16
From a mass balance and the definition of reflux:
Lmin = Vmin – D
Rmin = Vmin / D (17)
Step 3. Choose Theoretical Reflux Ratio
As the reflux ratio increases, the number of trays and thus the capital cost of the column
decreases. However, as a trade-off, an increase in reflux ratio will also increase the vapor
rate within the tower, thus increasing expenses such as condensers and reboilers
(Douglas, 1988). Most columns are designed to operate between 1.2 and 1.5 times the
minimum reflux ratio because this is approximately the region of minimum operating
cost. Therefore, based on first estimates, the operating reflux ratio for the analytically
method is equated so that (Douglas, 1988):
RTheor = 1.2 *Rmin (18)
17. CHE-396 Senior Design (Distillation)
17
Step 4. Determine Theoretical Number of Trays
• Modification of the Fenske Equation
A simplified approximate equation can be used to determine the number of trays
(Douglas, 1988). This is an expression for the minimum number of trays, assuming total
reflux and constant relative volatility. This equation takes into account the reflux ratio.
(19)
where
(20)
β Fractional recovery of light in the distillate
δ Fractional recovery of light in the bottom
α Relative volatility
R Reflux ratio
ZF Mole ratio of light component in feed
+
α
=
F
Z
*
R
1
1
ln
SF
ln
N
( ) ( )
( )
β
−
δ
−
δ
β
=
1
*
1
*
SF
18. CHE-396 Senior Design (Distillation)
18
Step 5. Determine Actual Number of Trays:
This is determined by taking the quotient of the number of theoretical trays to the tray
efficiency. Typical values for tray efficiency range from 0.5 to 0.7 (Douglas, 1988).
These values depend on the type of trays being used, as well as the internal liquid and
vapor flow rates.
Nactual = N/ε (21)
Step 6. Principal Dimensions of the Column (Diameter/Height):
• A design guideline that should be used is that the height of the column should
not be higher than 175 feet.
• Height-to-diameter ratio should be less than 20 to 30.
• Packed towers are used when the column has a small diameter (1.5 ft or less)
or area (1.77 ft2
or less) rather than plate towers.
• Either plate or packed towers may be used when the column diameter is
between 1.5-4.5 ft (or area, 1.77-15.9 ft2
).
• If the tower is higher than 190 ft, then a design with smaller tray spacing
should be considered (Douglas, 1988).
• Height of Column
The tower height can be related to the number of trays in the column. The following
formula assumes that a spacing of two feet between trays will be sufficient including
additional five to ten feet at both ends of the tower. This includes a fifteen percent excess
allowance of space (Douglas, 1988).
Htower = 2.3 Nactual [ft] (22)
19. CHE-396 Senior Design (Distillation)
19
• Vapor Velocity
Before we can determine the tower diameter, we need to determine the vapor velocity.
The vapor velocity can be derived from the flooding velocity. To limit our column from
flooding, we chose a velocity 60 percent of flooding velocity (Douglas, 1988). This is
assumed in the following equation:
(23)
where
V Vapor Velocity
ρG Density of the Gas
• Diameter of Tower
The diameter of a tower is relatively insensitive to changes in operating temperature or
pressure. The main determinant of the diameter is the vapor velocity. The desired vapor
velocity is dependent on the limitations of undesired column flooding. This equation
allows for a twelve percent surplus in area (Douglas, 1998).
DT = .0164√(V) * (MG/ ρm )^.25 (24)
where
V Vapor Velocity
MG
ρm Molar density
G
2
.
1
V
ρ
=
20. CHE-396 Senior Design (Distillation)
20
Section 3. Determining the Cost of Column and Components
All cost estimates formulas were taken from (Douglas, 1988).
Step 1. Cost of Column
• Capital Cost
The following approximates installed cost and purchased cost for the shell and trays.
This cost relates the diameter, height, and design variables of the column. The design
variable is a correction used to allow specificity of the column pressure and material.
(25)
where
Cc Cost of shell and trays
Fc Design considerations for the column
DT Diameter of column
H Height of column
Step 2. Cost of the Reboiler
• Capital Cost
The installed cost of the reboiler heat exchanger is:
(26)
where
Cr Cost of reboiler
∆Hv Heat of vaporization of bottoms
V Rate of Boilup
( )
c
8
.
0
T
c F
218
*
H
*
D
120
*
280
S
&
M
C +
=
65
.
0
65
.
0
v
r V
*
11250
H
*
328
*
280
S
&
M
C
∆
=
21. CHE-396 Senior Design (Distillation)
21
• Operating Cost
If we use steam to supply the heat for the reboiler, the temperature driving force must
be constrained to less than 30-45 F to prevent film boiling. We are also assuming a
high value of heat transfer coefficient because the heat transfer between a condensing
vapor and boiling liquid is high. The steam required is:
(27)
(28)
where
Ws Amount of steam needed
Cs Cost of steam
∆Hv Heat of vaporization
∆Hs Heat of saturation
V Mass flow rate
V
*
H
H
W
s
v
s
∆
∆
=
( ) V
*
H
*
SteamCost
*
10
*
74
.
8
C V
3
s ∆
= −
22. CHE-396 Senior Design (Distillation)
22
Step 3. Cost of Condenser
• Capital Cost
If we assume the cooling water is available at 90 F and a heat transfer coefficient
of 100, the heat transfer area of the condenser heat exchanger is:
Ac=((∆Hv/3000)⋅
ln (Tb-90/Tb-120))⋅
V (29)
where
Ac Area of condenser heat exchanger
∆Hv Heat of vaporization
Tb Bubble point of distillate
V Mass flow rate
The installed cost of the heat exchanger for condensing:
Cc=(M&S/280)*101.3*(2.29+Fc)*Ac0.65
(30)
where
Cc Cost of condenser
Fc Design considerations correction factor
• Operating Cost
If we assume the cooling water is available at 90 F and a heat transfer coefficient
of 100, the amount of cooling water needed for the condenser and the associated
cost is:
Wc=(∆Hv/30)V (31)
Cc=3.26⋅
10-4
*(Cooling water cost)(∆Hv)(V) (32)
where
Wc Amount of cold water to condenser
Cc Cost of condenser
∆Hv Heat of vaporization
V Mass flow rate
23. CHE-396 Senior Design (Distillation)
23
Step 4. Total Cost of Column
The total annualized cost is the sum of capital cost divided by the payback period plus
the yearly operating cost.
TAC = Capital Cost / Payback Period + Operating Cost (33)
24. CHE-396 Senior Design (Distillation)
24
Section 4. Case Study
Feed Stream, Acetone/Acetic Acid F=100mole/hr
Light-Key Mole Fraction, ZF=0.30
Percentage of Light in Distillate XD=0.90
Percentage of Light in Bottoms XB=0.10
Quality of Feed Q=1
We can simultaneously solve equations (1) and (2), F*Z
F=XD*D+XB*B and F=D+B, to
obtain the amount of distillate and bottoms:
100*.3=.9*D+.1*B
100=D+B
B=75mole/hr D=25mole/hr
The reflux ratio and number of trays were calculated graphically. These graphs can be
viewed after this section. The minumum reflux ratio can be calculated through a variation
of the Underwood equation. When the quality is equal to one and in a binary mixture,
equation (15) reduces to: Rmin =(1/(α-1))*((XD/XF)-α*(1-XD)/(1-XF))
Rmin=(1/(4.36-1))*((.9/.7)-4.36*.1/.3)
Rmin=.716
25. CHE-396 Senior Design (Distillation)
25
The theoretical minimum reflux ratio is derived from equation (18), R
theory=1.2*Rmin:
Rtheory=.859
From the Fenske equation (19) we can determine the number of trays:
Nmin=ln(81)/ln(4.36/√(1+1/(.81*.3))
N=5.97 Trays
26. CHE-396 Senior Design (Distillation)
26
The following three graphs show how we obtain approximately the same number of trays
graphically, rather than analytically (shown above).
Graph A, Acetone- Acetic Acid Equilibrium Data
( )
1
90
5
.
60
min +
=
R
( )
1
int min
+
= R
D
x
y
4876
.
0
min =
R
27. CHE-396 Senior Design (Distillation)
27
Graph B, Acetone- Acetic Acid Equilibrium
5861
.
0
4876
.
0
*
2
.
1
*
2
.
1 min =
=
= R
R
78
.
56
)
1
5851
.
0
(
90
int =
+
=
y
28. CHE-396 Senior Design (Distillation)
28
Graph C, Acetone- Acetic Acid Equilibrium Curve. We can see that the number of trays
is six. This can be seen from the stepping on the above graph. We note here that the
analytical method stated the number of trays to be 5.97, which is close to our graphical
method of 6 trays.
29. CHE-396 Senior Design (Distillation)
29
Alternatives
• Extraction: A process where one or more solutes are removed from a liquid by
transferring the solute(s) into a second liquid phase. Liquids must be immiscible or
partially immiscible. Vaporization is not required, thus extraction can be done at low
temperatures and is a gentle process suitable for unstable molecules (Wankat, 1988).
• Adsorption: Involves the transfer and equilibrium distribution of one or more solutes
between a fluid phase and particles. Liquid mixture is brought into contact with a
microporous solid allowing adsorption of certain components in the mixture takes
place on the internal surface of the solid. The adsorbent (solid) is insoluble in the
liquid, and the components being adsorbed are called solutes (Perry’
s, 1997).
• Condensation: Occurs when a saturated vapor comes in contact with a surface whose
temperature is below the saturation temperature. Film-type condensation occurs
when a film layer of condensate is formed on the surface. Dropwise condensation
occurs when appears in many small droplets at various points on the surface (Perry’
s,
1997).
• Reactive Distillation: Works by adding an entrainer that reacts with one component in
a mixture that is difficult to separate if relative volatilities of two components are very
close (less than 1.1). In the first column, the entrainer will react with one component
to increase the relative volatility so that it may be separated while in a second column,
the reaction can be reversed so that the entrainer can be recycled (King, 1980).
• Extractive Distillation: This operation requires two distillation columns. A heavy
nonvolatile component is added near the top of the tower to modify the activity
coefficients between two components. A pure component in the overhead in the first
column is obtained while the other component is recovered in the overhead in the
second column (King, 1980).
30. CHE-396 Senior Design (Distillation)
30
References
1. Seader, J. and Henley, E. Separation Process Principles. John Wiley & Sons,
1998, Chapters 7 and 8.
2. McCabe, Warren. Unit Operations of Chemical Engineering, Fifth Edition.
McGraw-Hill, Inc, 1993, Chapters 18 and 19.
3. Distillation Column Design. Copyright 1997.
http://lorien.ncl.ac.uk/ming/distil/distil0.htm
4. Douglas, James. Conceptual Design of Chemical Processes. McGraw-Hill, Inc.,
1988, Section A.3.
5. King, C. Judson. Separation Processes, Second Edition. McGraw-Hill, Inc.,
1980, Chapters 4-6.