72 + Interview Questions in Column Process Design in Distillation Design Page 2 InterviewSolution

51.	The concentration of multi component mixture in mass transfer process, can be represented by(a) Mass concentration(b) Molar concentration(c) Molar density(d) Each quantity is importantThis question was addressed to me during an online exam.Question is taken from Minimum Reflux for System Containing Distributed Monkeys topic in section Column Process Design, Optimization and Shortcut Calculations of Distillation Design
Answer» Correct CHOICE is (d) Each quantity is important The explanation is: The concentration of multi COMPONENT mixture can be REPRESENTED by all molar forms independent of PROPERTY, so concentration as well as density are EQUALLY important.

Discussion

52.	Dougles equation is useful for(a) Binary separations(b) Multicomponent separations(c) Tertiary Separations(d) Cant’ be specifiedThis question was addressed to me in final exam.My doubt is from The Jafarey, Dougles and Mcavoy Equation topic in section Column Process Design, Optimization and Shortcut Calculations of Distillation Design
Answer» The correct ANSWER is (b) Multicomponent SEPARATIONS Easy explanation: DOUGLES equation is useful for multicomponent separations extended form of smoker’s equation.

Discussion

53.	PHK stands for(a) Pre Heavy key(b) Pseudo Heavy key(c) Primary Heavy key(d) Pressure Heavy keyThe question was posed to me in my homework.The query is from The Jafarey, Dougles and Mcavoy Equation in chapter Column Process Design, Optimization and Shortcut Calculations of Distillation Design
Answer» Right OPTION is (b) Pseudo Heavy KEY Explanation: PHK STANDS for Pseudo Heavy key representing the bottom end products which are REMOVED at the bottom of COLUMN.

Discussion

54.	Smoker proposed an analytical closed form formula, to calculate(a) Reflux ratio(b) Number of trays(c) Number of stages(d) Number of feedsThis question was posed to me in a national level competition.Question is taken from Analytical X-Y Diagram -Smoker’s Equation in chapter Column Process Design, Optimization and Shortcut Calculations of Distillation Design
Answer» CORRECT option is (b) NUMBER of trays The EXPLANATION: In 1938, Smoker proposed an analytical closed FORM formula to calculate the number of stages in a binary distillation column.

Discussion

55.	The analytical formula fails to predict the(a) Equilibrium Stages(b) Reflux ratio(c) Feed inlet and outlet(d) Boil upI have been asked this question in an international level competition.The above asked question is from Analytical X-Y Diagram -Smoker’s Equation in section Column Process Design, Optimization and Shortcut Calculations of Distillation Design
Answer» Right ANSWER is (a) EQUILIBRIUM Stages Easy explanation: The ANALYTICAL formula fails to predict the Equilibrium Stages with reasonable ACCURACY, while reflux and boil up are predicted as ratio.

Discussion

56.	A non-key component may be distributed if(a) Close to that of one key(b) The Specified separation is sloppy(c) Intermediate between keys(d) Intermediate one keyI had been asked this question by my college director while I was bunking the class.This intriguing question comes from Reflux Stage Relationships topic in division Column Process Design, Optimization and Shortcut Calculations of Distillation Design
Answer» Right CHOICE is (B) The Specified SEPARATION is SLOPPY For explanation: For distributed systems the Specified separation is sloppy, while for the distributed system it is close to that of one KEY.

Discussion

57.	The number of theoretical stages, depends on the(a) Stepping off the tray(b) Reflux ratio(c) Operating line(d) Flow ratesThe question was posed to me in an international level competition.Question is taken from Minimum Stages topic in portion Column Process Design, Optimization and Shortcut Calculations of Distillation Design
Answer» Right CHOICE is (B) Reflux RATIO The explanation: The number of THEORETICAL STAGES depends on the reflux ratio R = L0/D, while the reflux ratio itself depends upon the operating line.

Discussion

58.	In binary system, Separation is very efficient when relative volatility is(a) 1(b) >1(c)
Answer» CORRECT CHOICE is (b) >1 The explanation: If α >1 efficiency of separation increases, if separation is difficult then α < 1 and if no separation is possible then α= 0.

Discussion

59.	For a change in temperature ______ is added to tn.(a) Half(b) One fourth(c) Two third(d) SquareI have been asked this question in exam.This is a very interesting question from Analysis of Existing Columns with Brinkley Method in division Column Process Design, Optimization and Shortcut Calculations of Distillation Design
Answer» CORRECT option is (a) HALF For EXPLANATION: For a change in temperature half is added to tn and half to tm, this acts as an average VALUE between them¬ provides ACCURACY.

Discussion

60.	If the flow rates of liquid and distillate are 150 kmol/h and 100 kmol/h. Find reflux ratio?(a) 90(b) 50(c) 15(d) 30This question was posed to me during an internship interview.The origin of the question is Minimum Reflux in portion Column Process Design, Optimization and Shortcut Calculations of Distillation Design
Answer» CORRECT ANSWER is (c) 15 Easiest EXPLANATION: Reflux is given by L/D = 150/100 = 15.

Discussion

61.	A non-key component may be distributed, if it has volatility(a) Very far to one from other keys(b) Same as that of non-key(c) Very close to that of one keys(d) Constant Molar OverflowI had been asked this question in an interview for internship.I want to ask this question from Minimum Reflux topic in division Column Process Design, Optimization and Shortcut Calculations of Distillation Design
Answer» The CORRECT answer is (c) Very close to that of one keys To EXPLAIN: Volatility that very close to that of one keys is not disturbed, as constant molar OVERFLOW RESIDES for the column feed assumptions.

Discussion

62.	The ratio of the key components is essentially equal to their ratio in liquid feed, was given by?(a) Underwood(b) Gilliland(c) Brown-Martin(d) FenskeThe question was asked during an internship interview.The query is from Minimum Reflux topic in chapter Column Process Design, Optimization and Shortcut Calculations of Distillation Design
Answer» Right ANSWER is (c) Brown-Martin To explain: This method was based on the observation that a FEED PINCH point, Fenske is based on feed COMPOSITIONS of the SYSTEM.

Discussion

63.	The underwood’s equation, implies of using trial and error for finding(a) Θ(b) α(c) β(d) ΩThis question was addressed to me by my school teacher while I was bunking the class.The above asked question is from Minimum Reflux topic in section Column Process Design, Optimization and Shortcut Calculations of Distillation Design
Answer» The CORRECT choice is (a) Θ The best EXPLANATION: We find θ which MUST lie between RELATIVE volatilities of the keys, while α DENOTES the relative volatility of components.

Discussion

64.	Raising the column pressure, results in(a) Lower relative volatility(b) Higher relative volatility(c) No effect(d) Higher boiling pointThis question was posed to me in an interview for job.This interesting question is from Process Design and Optimization topic in section Column Process Design, Optimization and Shortcut Calculations of Distillation Design
Answer» CORRECT option is (a) LOWER relative VOLATILITY To elaborate: The unfavorable effects of raising column pressure is that it lowers relative volatility and thus discarding the products FORMATION.

Discussion

65.	At minimum reflux, No. stages are(a) Unity(b) Infinite(c) Zero(d) NegativeI got this question in an interview.This interesting question is from Minimum Stages in portion Column Process Design, Optimization and Shortcut Calculations of Distillation Design
Answer» Correct ANSWER is (b) Infinite The best I can EXPLAIN: MINIMUM reflux and stages are inversely proportional relation, while at MAXIMUM reflux the number of stages are ZERO.

Discussion

66.	In the below diagram, the minimum reflux can be seen as ______ using smoker’s equation.(a) 1.567(b) 1.425(c) 1.2(d) Can’t be specifiedI have been asked this question in semester exam.My question is based upon Analytical X-Y Diagram -Smoker’s Equation topic in portion Column Process Design, Optimization and Shortcut Calculations of Distillation Design
Answer» Right option is (b) 1.425 The BEST explanation: By TRACKING the LOCUS to the x axis of smoker’s line REFLUX is seen to be intersecting at the ABSCISSA of 1.425 on the x axis.

Discussion

67.	Heavy non-keys end up as a(a) Final product(b) Feed outlet(c) Bottom end product(d) Overhead productThe question was asked in my homework.This interesting question is from Minimum Reflux for System Containing Distributed Monkeys in portion Column Process Design, Optimization and Shortcut Calculations of Distillation Design
Answer» Correct option is (c) Bottom END PRODUCT Best EXPLANATION: Heavy non-keys always end up as a Bottom end product, this occurs DUE to volatility difference in the components.

Discussion

68.	Jafarey, Dougles and Mcavoy Equation is capable of predicting(a) Column performance(b) Column feed rate(c) Column design(d) Column diameterI had been asked this question in an online interview.My enquiry is from The Jafarey, Dougles and Mcavoy Equation in chapter Column Process Design, Optimization and Shortcut Calculations of Distillation Design
Answer» Right answer is (a) Column performance To EXPLAIN I would say: Jafarey, DOUGLES and Mcavoy EQUATION is capable of predicting Column performance and control of disturbances.

Discussion

69.	If the feed temperature is 2110K and Bubble point is 70^oF, then tm is(a) 68^oF(b) 178^oF(c) 140.5^oF(d) 259.5^oFI had been asked this question by my college professor while I was bunking the class.My enquiry is from Analysis of Existing Columns with Brinkley Method in chapter Column Process Design, Optimization and Shortcut Calculations of Distillation Design
Answer» CORRECT OPTION is (d) 259.5^oF Explanation: As TM= (308+211)/2 = 259.5^oF.

Discussion

70.	The term S in the Fenske’s equation, is given as(a) (xLKxHK)D(xLKxHK)B(b) (xLKxHK)D(xLKxHK)L(xLKxHK)R(c) (xLKxHK)L(xLKxHK)V(d) (xLKxHK)HK(xLKxHK)LKThe question was posed to me in an internship interview.I want to ask this question from Reflux Stage Relationships topic in section Column Process Design, Optimization and Shortcut Calculations of Distillation Design
Answer» CORRECT OPTION is (a) (xLKxHK)D(xLKxHK)B To EXPLAIN: The term S in the FENSKE’s equation is given as (xLKxHK)D(xLKxHK)B, representing High and Low keys of the GAS and liquid phases.

Discussion

71.	For value of m, the change in liquid concentration is independent of tray location if(a) L/V = 1(b) V/L =1(c) L/mV=1(d) Vm/L=1I have been asked this question by my school teacher while I was bunking the class.This intriguing question comes from Minimum Stages topic in section Column Process Design, Optimization and Shortcut Calculations of Distillation Design
Answer» Correct option is (c) L/mV=1 Easy EXPLANATION: At this CONDITION slope of operating line equals to slope of equilibrium line, i.e. m = 1 this shows the steady STATE operation.

Discussion

72.	If x=0.4 and y =0.6633 and point xD (0.9, 0.9). Then estimate Rmin(a) 0.9(b) 0.4734(c) 0.4(d) 0.66The question was posed to me in a job interview.My question is taken from Minimum Stages topic in division Column Process Design, Optimization and Shortcut Calculations of Distillation Design
Answer» The CORRECT ANSWER is (a) 0.9 The EXPLANATION is: As Rmin/R+1 = (0.9-0.6633)/ (0.9/0.4) = 0.4734 then 0.4734/1-0.4734 = 0.9.

Discussion

Explore topic-wise InterviewSolutions in .

PHK stands for(a) Pre Heavy key(b) Pseudo Heavy key(c) Primary Heavy key(d) Pressure Heavy keyThe question was posed to me in my homework.The query is from The Jafarey, Dougles and Mcavoy Equation in chapter Column Process Design, Optimization and Shortcut Calculations of Distillation Design

In binary system, Separation is very efficient when relative volatility is(a) 1(b) >1(c)

At minimum reflux, No. stages are(a) Unity(b) Infinite(c) Zero(d) NegativeI got this question in an interview.This interesting question is from Minimum Stages in portion Column Process Design, Optimization and Shortcut Calculations of Distillation Design

If x=0.4 and y =0.6633 and point xD (0.9, 0.9). Then estimate Rmin(a) 0.9(b) 0.4734(c) 0.4(d) 0.66The question was posed to me in a job interview.My question is taken from Minimum Stages topic in division Column Process Design, Optimization and Shortcut Calculations of Distillation Design