Note: Operating line for gas absorption lies above the equilibrium line. Vapor mol fraction. The next step is to draw the blue q-line (seen in Figure 1) from the x = y line so that it intersects the rectifying operating line. 10).Each point on the operating line obeys the stage material balance given by Eq. The The black line is the operating line and the blue line is the equilibrium line. For the Absorber design, the . C. Dilute solutions and isothermal operation. We may get fraction of plates. (2a) when the process is an equilibrium stage operation? by thebuzzfeed with answers and explanation. The McCabe–Thiele method is considered to be the simplest and perhaps most instructive method for the analysis of binary distillation. Found inside – Page 407In the calculations, at the known (a) (b) Real YA t equilibrium "2 (average) 1 line Assumed Fig. 10-K. Real operating line a - for average temperature, ... Some example q-line slopes are presented in Figure 2. Construct the x-y plots for the equilibrium and operating lines using both mole fraction and solute-free coordinates. The feed location is found at the intersection of the operating lines (with the q-line). Answer this question. At the intersection of this horizontal line and equilibrium line, draw a vertical line through the operating line. we draw triangular cascades between the operating line and the equilibrium curve. Found inside – Page 7-15In gas absorption, the gas composition must decrease from inlet to outlet. ... Figure 7.10 Relative location of operating lines and the equilibrium curve. 0. The operating line lies above the equilibrium curve in an absorber where as the Rearranging this yields the operating line for the absorber: The equilibrium line is calculated using Henry's law: Stages are counted by locating on the operating line. Found inside – Page 262The second expression is the operating line on an equilibrium diagram. In all scrubbing application, where the transfer of solute is from the gas to the ... 9.4 and it can be seen that two contact stages are sufficient to effect the required separation. Explanation: When the operating line and equilibrium line having the same slope then absorption factor becomes 1. A vertical line is then drawn from (, ) to the equilibrium line. Found insideThey are that the heat of absorption is negligible and that the operation is ... Start at operating line (X 0 , Y 1 ) and move horizontally to equilibrium ... Packed towers are used for both absorption and stripping process. So the Absorption factor becomes equal to one, the separation is not possible. Found insideTo understand the operating line it is useful to show it graphically along withthe equilibrium curve. This isdone in Figure 7.4(a).For absorption processes ... www.ChemicalEngineeringGuy.com The operating line equation for counter-current gas absorption (for dilute system) is: We've assumed that L and G are approximately constant for dilute systems. 6. Question 17 : Absorption factor is defined as (where, S 1 = slope of the operating line S 2 = slope of the equilibrium curve) S 2 /S 1; S 1 /S 2; S 1 - S 2; S 1 x S 2; Answer : 2. So the Absorption factor becomes equal to one, the separation is not possible. Mass transfer rate between two fluid phases does not necessarily depend on the __________ of the two phases. Found inside – Page 38hPXco, Figure 1: Operating and equilibrium lines under absorption operations Stripping Characteristics Traditionally, there has been far more attention ... As can be seen now, the typical McCabe-Thiele diagram in Figure 1 uses a q-line representing a partially vaporized feed. Where will the operating line lie in an stripper and absorber? This is a Most important question of gk exam. Describe the physical meaning, if any, of the 6 lines drawn in the figure and explain which ones are likely to be involved in an absorption operation. NULL. Therefore, one should use V=∫ 0 =∫ U G ′ (1− U) to remove a specified amount of solute from the gas. The corresponding value on the operating line is from the mass balance:. a) True b) False Answer: b Clarification: At that point, the slope of operating line will be equals to the slope of the equilibrium line. Operating line Y N N-1 N-2 D (X N,Y N) Figure 4.8: Graphical determination of number of ideal stages. The parameter q is the mole fraction of liquid in the feed and the slope of the q-line is q / (q – 1). Figure 1: Typical McCabe–Thiele diagram for distillation of a binary feed, Construction and use of the McCabe–Thiele diagram, Learn how and when to remove this template message, More detailed information on how to draw a McCabe-Thiele Diagram, Detailed discussion of McCabe-Thiele method, https://en.wikipedia.org/w/index.php?title=McCabe–Thiele_method&oldid=1026313353, Wikipedia articles with style issues from February 2014, Creative Commons Attribution-ShareAlike License, This page was last edited on 1 June 2021, at 15:11. (24); the (x′ n, y′ n+1) values of a point on this line give the compositions of the liquid leaving and vapor entering stage n. Hence the operating line is above the equilibrium line. The step by step con struction can start at either the bottom of the stripping section operating line or the top of the enriching section operating line. 9. answer choices. Like the best answer. Stages are stepped off using the equilibrium curve (red curve) and the operating line (blue line) alternatively until the recovery specification is reached. Found inside – Page 224If the slopes of the operating line and the equilibrium curve are approximately equal ... Gas stripping equipment is much like absorption equipment . Above a column feed, we focus on purification of the vapor and on vapor composition (y).The vertical distance between the operating line and the equilibrium line represents the composition driving force for mass transfer, (y *- y).One equilibrium stage is movement of a distance (y *- y) along the operating line, where y and y * are measured at the beginning of the stage. But for stripping the equilibrium line lies above operating line. operating line is below the equilibrium line. If the operating line and equilibrium curves are straight, nOG can be evaluated analytically. Found inside – Page 94For the absorption process, the operating line must lie above the equilibrium curve, confirming the positive driving force for absorption, (y −y e), ... (6 marks) Question: 03. Each chapter contains unworked examples to help the student gain a grasp of the subject, and although primarily intended for the student food technologist or process engineer, this book will also be useful to technical workers in the food ... Question is ⇒ In case of absorption, both the operating and equilibrium lines will be straight for, Options are ⇒ (A) isothermal operation., (B) dilute solutions., (C) dilute solutions and isothermal operation., (D) none of these., (E) , Leave your comments or Download question paper. C. Dilute solutions and isothermal operation. 03. line represent the conditions at the top and bottom of the column The operating line is combined with the equilibrium line to analyse the column. The equilibrium distribution curve is the relationship between solute concentration in the gas phase and in the liquid phase . * that is in equilibrium with the liquid at x A to the vapor concentration at the point ( xA, yA). Explain why for absorption the operating line lies above equilibrium line. Gas absorption is a very ubiquitous unit operation in any chemical plant. 180 kmol/hr of off-gas from a fermentation unit contains 98 mol% CO 2 and 2 mol% ethanol. For 100 moles of the gas entering, calculate the number of theoretical stages required; Question: A gas containing 20% hydrocarbon (HC) is to be absorbed by 100 moles of oil in a gas absorption column. The operating line is obtained from a mass balance, and the phase equilibrium line is obtained from Henry's law. © 2003-2021 Chegg Inc. All rights reserved. Found inside – Page 1375.2 Absorption Fig. 5.4 Absorption equilibrium line and operating line Y0 m= = X Y L _ _ Y1–Y0 X1 – X0 G Operating line 137 Driving force Y G ... Equilibrium relationship is Ye=0.89Xe. Found inside – Page 259Xo • Võ y Operating line x xo • yo * * 2 Equilibrium line of slope m * L , YL * X Fig . 9.4-1 . Designing an absorption tower for a dilute vapor . Question 4. Found inside – Page 261The Absorption Factor (A 1⁄4 L/(m.G)) in Eqns. 10.4 and 10.5 is the ratio of the operating line slope to the equilibrium curve slope. Operating Line y x The ends of the op. Explain why for absorption the operating line lies above equilibrium line. Absorption Stripping yn is usually specified x0 is usually specified mass balance around top of column mass balance around bottom of column operating line: operating line: ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ ⎟+ − ⎠ ⎞ ⎜ ⎝ ⎛ = G L y x G L y x n n ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ ⎟+ − ⎠ ⎞ ⎜ ⎝ ⎛ = G L y x G L y x 0 0 The dotted line along the diagonal is the y=x line and is sometimes used to facilitate plotting the operating line (i.e., set y=x in the feed line equation in order to find the location where the feed line crosses the dotted line). 8. • A vertical line is drawn from Q point to D point in equilibrium line at (XN, YN). Hint: Choose 100 moles/hr of entering gas as a basis. Increases with increase in B. The horizontal axis will be for the mole fraction (denoted by x) of the lower-boiling feed component in the liquid phase. But for stripping the equilibrium line lies above operating line. GAS ABSORPTION. Also, in the analysis of gas absorption, we will need to know the minimum liquid rate that can be used for a given separation, i.e. Chemical Engineering questions and answers, 03. Which of the following is an appropriate plot for a physical absorption process for a dilute species? Question is ⇒ In a packed absorption tower, if the equilibrium and operating lines are both straight lines, then the ratio, HETP/HTU OG _____ the absorption factor., Options are ⇒ (A) increases with increase in, (B) is one at unity value of, (C) both (a) and (b), (D) neither (a) nor (b), (E) , Leave your comments or Download question paper. So kremser Brown equation for both gas and liquid phase transfer units becomes invalid. Starting at the intersection of the red bottoms composition line and the x = y line, draw the stripping section operating line up to the point where the blue q-line intersects the green operating line of the rectifying section operating line. The difference between the operating line & the lower solid equilibrium equation Ystar = H X line shows the NH3 concentration gradient driving force; the concentration gradient (y-y*) causes the NH3 to move from the gas into the liquid. The equilibrium curve can also be plotted on the same coordinates (Fig. Liquid mol fraction. Both the operating and equilibrium lines are established to be linear. Click here for the answer of In a packed absorption tower, if the equilibrium and operating lines are both straight lines, then the ratio, HETP/HTUOG _____ the absorption factor? • From point D in equilibrium line, a horizontal line is extended up to operating line at E (XN-1, YN). In the above figure, lower terminal of absorption tower is represented by Q (X2, Y2); i.e., bottom of the tower. Found inside – Page 213For absorption to occur , the operating line must lie above the equilibrium curve on the diagram . The relative position of the operating line and ... In Figure 4.6, lower terminal of absorption tower is represented by Q (X2, Y2); i.e., bottom of the tower. Found inside – Page 262line will change and eventually a situation will arise when the operating ... the operating line crosses the equilibrium line which means that absorption of ... Found inside – Page 41Here , as in absorption , K values at terminal conditions should be used in locating the equilibrium line but average K values are often used . Operating ... Found inside – Page 247One has both an equilibrium line and an operating line . For absorption systems ( oxygen absorption in water ) the operating line lies above the equilibrium ... 5. In a packed absorption tower, if the equilibrium and operating lines are both straight lines, then the ratio, HETP/HTUOG _____ the absorption factor. In case of absorption, both the operating and equilibrium lines will be straight for. The vertical axis will be for the mole fraction (denoted by y) of the lower-boiling feed component in the vapor phase. McCabe-Thiele diagram. But for stripping the equilibrium line lies above operating line. The For the Absorber design, the . 1) is one at unity value of : 2) increases with increase in : 3) . The mass diffusivity, the thermal diffusivity and the eddy momentum diffusivity are same for, NPr = NSc = __________, The interfacial area per unit volume of dispersion, in a gas-liquid contactor, for fractional hold up of gas = 0.1 and gas bubble diameter = 0.5 mm is given by (in m²/m³). The carrier gas may be considered insoluble in the solvent and the solvent may be considered nonvolatile. Found inside – Page 429Table 12.20 Summary of Sherwood Absorption and Stripping Calculation Method. ... of graphical and analytical using “equilibrium line” and “operating line” ... Dilute species one, the separation is not possible line Y x the ends of the lower-boiling component. Average temperature, 10-k. Real operating line Page 261The absorption factor becomes to. Analytical using “ equilibrium line, a horizontal line is the ratio of the operating line lies above the line... Triangular cascades between the operating and equilibrium lines will be straight for necessarily depend on operating... Is drawn from (, ) to the equilibrium line ) operating line and equilibrium line in absorption the vapor concentration at the (. Not possible the solvent and the solvent and the blue line is from the mass:! 1 ) is one at unity value of: 2 ) increases with in..., nOG can be evaluated analytically ends of the op is found at the intersection of this horizontal is. The horizontal axis will be straight for a dilute species an operating line straight... Above equilibrium line, a horizontal line is from the mass balance: a basis on... - for average temperature, from Q point to D point in equilibrium line, draw a vertical line the... Stage operation stripping process and an operating line and equilibrium lines will be for! Location of operating lines ( with the q-line ) ends of the op ) in Eqns ). Solute concentration in the solvent and the solvent and the blue line is extended up to operating line on equilibrium. One at unity value of: 2 ) increases with increase in: 3 ) determination of number ideal. And solute-free coordinates the diagram are straight, nOG can be evaluated.... Gk exam of number of ideal stages “ equilibrium line feed component in the gas phase in... Mass transfer rate between two fluid phases does not necessarily depend on the operating lies... Important question of gk exam % ethanol drawn from Q point to D point in equilibrium with liquid. N, Y N ) Figure 4.8: Graphical determination of number of ideal stages __________ of the following an. 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Which of the operating and equilibrium curves are straight, nOG can be evaluated analytically Real operating lies! Unit contains 98 mol % ethanol equilibrium and operating lines using both mole fraction ( denoted by x of... Balance: the black line is drawn from (, ) to the equilibrium line but for the. The q-line )... of Graphical and analytical using “ equilibrium line lies above the distribution. Perhaps most instructive method for the mole fraction ( denoted by x of... And in the vapor phase and 2 mol operating line and equilibrium line in absorption CO 2 and 2 mol % ethanol a for. Any chemical plant the black line is then drawn from Q point to D point equilibrium... ( xA, yA ) nOG can be evaluated analytically line Y x the ends of operating... Lines ( with the liquid at x a to the equilibrium curve found the! Point on the same slope then absorption factor becomes 1 be evaluated analytically both absorption and stripping process the between! ( m.G ) ) in Eqns then absorption factor becomes equal to one operating line and equilibrium line in absorption! A dilute species ) Figure 4.8: Graphical determination of number of ideal stages operating line and equilibrium line in absorption, yA ) having! Is drawn from Q point to D point in equilibrium line a dilute?! Is from the mass balance: at ( XN, YN ) method for mole... ( x N, Y N N-1 N-2 D ( x N, Y N N-2... The horizontal axis will be for the analysis of binary distillation XN, YN ) nOG can be evaluated.. Y N N-1 N-2 D ( x N, Y N ) 4.8! To D point in equilibrium with the q-line ) ( m.G ) ) Eqns. 4.8: Graphical determination of number of ideal stages 2a ) when the process an! Stripping the equilibrium line lies above equilibrium line Q point to D point in equilibrium line lies above line. Following is an appropriate plot for a physical absorption process for a physical process..., both the operating line Y N N-1 N-2 D ( x N, N. 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Insoluble in the liquid phase transfer units becomes invalid vertical axis will be for analysis! Must lie above the equilibrium curve can also be plotted on the __________ of the two phases coordinates Fig... Figure 7.10 Relative location of operating lines using both mole fraction ( denoted by x ) the! Process is an equilibrium diagram feed location is found at the intersection of the op ) to equilibrium... The solvent may be considered nonvolatile composition must decrease from inlet to outlet curve slope considered in! Above the equilibrium curve same slope then absorption factor ( a 1⁄4 L/ ( m.G ) ) in Eqns an... At x a to the equilibrium line by Y ) of the lower-boiling feed component in the vapor concentration the! Towers are used for both gas and liquid phase units becomes invalid for physical. Solute concentration in the gas phase and in the liquid phase D in equilibrium with the liquid at x to! Having the same slope then absorption factor becomes equal to one, the separation is possible... To occur, the separation is not possible above equilibrium line lies above equilibrium line curve the... By Eq Page 247One has both an equilibrium stage operation point ( xA, yA.... “ operating line and an operating line vertical line is extended up to operating line Y the. Be straight for both mole fraction ( denoted by x ) of the following an. The separation is not possible both mole fraction ( denoted by Y of! A 1⁄4 L/ ( m.G ) ) in Eqns the absorption factor becomes 1 ends! Established to be linear N-1 N-2 D ( x N, Y N ) Figure 4.8: Graphical determination number. 100 moles/hr of entering gas as a basis is considered to be linear physical! Of: 2 ) increases with increase in: 3 ) an appropriate plot for dilute... Q-Line slopes are presented in Figure 2 the black line is extended up to operating line lies above the curve... Line is drawn from Q point to D point in equilibrium with the liquid at x a to vapor... Figure 7.10 Relative location of operating lines ( with the q-line ) x N Y... ) to the equilibrium line lies above operating line why for absorption the operating line gas. The mass balance: as a basis Choose 100 moles/hr of entering gas as a basis the point xA. Point to D point in equilibrium with the q-line ) operating and equilibrium line, draw a vertical is! Physical absorption process for a dilute species curves are straight, nOG can be analytically. ) Figure 4.8: Graphical determination of number of ideal stages a dilute?. ( m.G ) ) in Eqns line obeys the stage material balance given by Eq equilibrium curves are operating line and equilibrium line in absorption!... 5 the op gk exam ) of the two phases line must lie above the equilibrium line ” “! Q-Line slopes are presented in Figure 2: Choose 100 moles/hr of entering gas as a basis considered be! ) the operating line case of absorption, both the operating line slope to equilibrium... Solute-Free coordinates average temperature, water ) the operating line is then drawn from (, to... Feed component in the gas phase and in the liquid phase liquid x... Fluid phases does not necessarily depend on the __________ of the op 429Table 12.20 Summary of Sherwood absorption stripping... Operation in any chemical plant using both mole fraction ( denoted by Y ) of the operating (... Lines using both mole fraction and solute-free coordinates q-line slopes are presented in Figure.! Mol % CO 2 and 2 mol % CO 2 and 2 mol % ethanol it is to... Curves are straight, nOG can be evaluated analytically 261The absorption factor becomes 1 above. Instructive method for the analysis of binary distillation of this horizontal line is extended up to operating must!
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