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1.	Which of the following does not control the design of fluid – solid reactor?(a) Reaction kinetics for single particles(b) Density of fluid being treated(c) Size distribution of solids(d) Flow patterns of solids and fluidI got this question by my school teacher while I was bunking the class.I'd like to ask this question from Design of Fluid Particle Reactors topic in portion Fluid-Particle Reactions: Kinetics of Chemical Reaction Engineering
Answer» Correct choice is (b) Density of fluid being treated Easiest explanation: The COMPLEXITY of the reaction determines the use of FLOW reactor or PLUG flow reactor. The variation of temperature conditions determines the flow patterns of fluid by AFFECTING the viscosity. The range of sizes determines the OPERATIONAL factors.

2.	If \(\frac{τ}{t}\) = 0.5, average conversion for a particle B of constant size in a mixed flow reactor for film resistance controlling is ____(a) 0.45(b) 0.38(c) 0.536(d) 0.743This question was posed to me during an online exam.This question is from Design of Fluid Particle Reactors in section Fluid-Particle Reactions: Kinetics of Chemical Reaction Engineering
Answer» The correct choice is (C) 0.536 For EXPLANATION: 1-\(\OVERLINE{X_{(B)}}\) = 0.5(\(\FRAC{τ}{\overline{t}}) – \frac{1}{3!}(\frac{τ}{\overline{t}})^2+\frac{1}{4!} (\frac{τ}{\overline{t}})\)^3-…, as obtained by expansion. 1-\(\overline{X_{(B)}}\) = 0.4635 and \(\overline{X_{(B)}}\) = 0.536

3.	For mixed flow of particles containing a single unchanging size and uniform gas composition, the fraction unconverted for chemical reaction controlling is ____(a) \(\int_0^τ\)(1-\(\frac{t}{τ}\))^3\(\frac{e}{t}^\frac{-t}{t}\) dt(b) \(\int_0^τ\)(1-\(\frac{t}{τ}\))^2\(\frac{e}{t}^\frac{-t}{t}\) dt(c) \(\int_0^τ\)(1-\(\frac{t}{τ}\))\(\frac{e}{t}^\frac{-t}{t}\) dt(d) \(\int_0^τ\)(1-\(\frac{t}{τ}\))^0.5\(\frac{e}{t}^\frac{-t}{t}\) dtThe question was posed to me in class test.My question is from Design of Fluid Particle Reactors in division Fluid-Particle Reactions: Kinetics of Chemical Reaction Engineering
Answer» The correct choice is (a) \(\int_0^τ\)(1-\(\frac{t}{τ}\))^3\(\frac{e}{t}^\frac{-t}{t}\) dt Best EXPLANATION: For chemical REACTION controlling, \(\frac{t}{τ}\) = 1-(1- XB)\(^\frac{1}{3}\). Hence, 1-\(\overline{X_{(B)}}\) = ∫0^τ(1-\(\frac{t}{τ}\))^3\(\frac{e}{t}^\frac{-t}{t}\) dt.

4.	If \(\frac{τ}{t}=\frac{1}{3},\) average conversion for a particle B of constant size in a mixed flow reactor for chemical reaction controlling is ____(a) 0.92(b) 0.98(c) 0.75(d) 0.76I have been asked this question at a job interview.I'd like to ask this question from Design of Fluid Particle Reactors topic in division Fluid-Particle Reactions: Kinetics of Chemical Reaction Engineering
Answer» The correct CHOICE is (a) 0.92 For explanation I would say: \(\overline{X_{(B)}} = 3(\frac{\overline{t}}{τ}) -6 (\frac{\overline{t}}{τ})^2+ 6(\frac{\overline{t}}{τ})^3(1-e^\frac{τ}{\overline{t}}, 1-\overline{X_{(B)}}\) = 0.078 and \(\overline{X_{(B)}}\) = 0.92

5.	State true or false.The fluidized bed reactor is used for mixed flow of solids.(a) The fluidized bed reactor is used for mixed flow of solids.(b) True(c) FalseThe question was posed to me in an international level competition.Origin of the question is Design of Fluid Particle Reactors in division Fluid-Particle Reactions: Kinetics of Chemical Reaction Engineering
Answer» Right OPTION is (a) The fluidized bed reactor is used for MIXED FLOW of SOLIDS. The BEST I can explain: Fluidised bed provides high agitation of solids by high fluid velocity. The gas flow is more complicated than mixed flow.

6.	If weight of all solids in the reactor is 300kg and the feed rate of solids is \(\frac{50kg}{hr},\) then the mean residence time(in hrs) of a material of a given size for mixed flow of a mixture of sizes of unchanging size particles is ____(a) 7(b) 6(c) 4(d) 3I had been asked this question during an interview.The query is from Design of Fluid Particle Reactors topic in division Fluid-Particle Reactions: Kinetics of Chemical Reaction Engineering
Answer» The correct choice is (b) 6 To explain: t = \(\FRAC{W}{F} = \frac{300}{50}\) = 6 HRS.

7.	For mixed flow of particles containing a single unchanging size and uniform gas composition, the fraction unconverted for film resistance controlling is ____(a) \(\int_0^τ\)(-\(\frac{t}{τ}\))\(\frac{e}{t}^\frac{-t}{t}\) dt(b) \(\int_0^τ\)(1 – \(\frac{t}{τ}\))\(\frac{e}{t}^\frac{-t}{t}\) dt(c) \(\int_0^τ\)(1 –\(\frac{t}{τ}\))dt(d) \(\int_0^τ\)(1 – \(\frac{t}{τ}\))\(\frac{e}{t}^\frac{-t}{t}\) dtI had been asked this question by my college professor while I was bunking the class.The question is from Design of Fluid Particle Reactors in portion Fluid-Particle Reactions: Kinetics of Chemical Reaction Engineering
Answer» Right option is (b) \(\int_0^τ\)(1 – \(\frac{t}{τ}\))\(\frac{e}{t}^\frac{-t}{t}\) dt For explanation I would say: For a mixed flow reactor, the mean RESIDENCE time, t in the reactor is, E = \(\frac{e}{t}^\frac{-t}{t}\). For a single SIZE of particles converted in time τ,1-\(\overline{X_{(B)}}\) = ∫0^τ(1 – XB)\(\frac{e}{t}^\frac{-t}{t}\)dt for an INDIVIDUAL particle. For film resistance controlling, XB = \(\frac{t}{τ}.\)

8.	Which of the following does not provide plug flow of Solid – fluids?(a) Fluidised bed reactor(b) Countercurrent flow in blast furnaces(c) Crossflow in moving belt(d) Concurrent flow in driersThis question was posed to me during a job interview.I'm obligated to ask this question of Design of Fluid Particle Reactors in section Fluid-Particle Reactions: Kinetics of Chemical Reaction Engineering
Answer» The CORRECT option is (a) Fluidised bed reactor For explanation I would SAY: Blast FURNACES and cement kilns provide PLUG FLOW in countercurrent operation. Moving belt feeders are used in furnaces. Cocurrent flow is employed in polymer driers.

9.	If \(\overline{X_{Ri}}\) is the mean conversion of a reactant of particle size Ri, Rm is the particle of maximum size in the feed and F(Ri) is the fraction of Ri fed to the reactor, then the mean conversion of solids of a particular size ‘i’ leaving a plug flow reactor converting a mixture of particles of varying sizes is ____(a) \(\overline{X_{(B)Ri}} = ∑_{R(τ)}^{Rm}\)[1- X(B)Ri]\(\frac{F(Ri)}{F} \)(b) 1-\(\overline{X_{(B)Ri}} = ∑_{R(τ)}^{Rm}\)[ XRi]\(\frac{F(Ri)}{F} \)(c) 1-\(\overline{X_{(B)Ri}} = ∑_{R(τ)}^{Rm}\)[1-X(B)Ri]F (Ri)(d) 1-\(\overline{X_{(B)Ri}} = ∑_{R(τ)}^{Rm}\)[1-X(B)Ri] \(\frac{F(Ri)}{F} \)The question was posed to me during an online interview.Enquiry is from Design of Fluid Particle Reactors in portion Fluid-Particle Reactions: Kinetics of Chemical Reaction Engineering
Answer» The correct choice is (d) 1-\(\OVERLINE{X_{(B)Ri}} = ∑_{R(τ)}^{Rm}\)[1-X(B)Ri] \(\frac{F(Ri)}{F} \) To elaborate: MEAN value for fraction of ‘i’ unconverted is the summation of the product of fraction of the REACTANT unconverted in the particle size Ri and the fraction of feed in the size Ri. 1-\(\overline{X_{(B)Ri}}\) = ∑(fraction of the reactant unconverted in the particle size Ri × the fraction of feed in the size Ri).