Chemical Engineering Answers

How do you choose minimum solvent required for the single stage extraction? Explain.

Explain Breakthrough curve in fixed bed adsorbers.

A solution of washed raw cane sugar is coloured by the presence of impurities. It is to be decolourised by the treatment with an adsorptive carbon in a contact filtration plant. The data for an equilibrium isotherm is given below. The original solution has a colour concentration of 9.6 measured on an arbitrary scale and it is desired to reduce colour to 10% of its original value Kg carbon/kg solution: 0 0.001 0.004 0.008 0.02 0.04 Colour units /kg solution 9.6 8.6 6.3 4.3 1.7 0.7

Convert the data to a suitable form for plotting the equilibrium isotherm and determine the quantity of fresh carbon required per 1000 kg of solution for a two stage counter-current operation.

A mixture containing benzene and toluene with 40% benzene and 60% toluene is to be separated in a fractionating column to give a product containing 96% benzene, bottom product containing 95% toluene. Feed is mixture of two third vapor and one third liquid. Find out the number of theoretical stages required if the reflux ratio of 15 times the minimum is used. Relative volatility is 2.5(McCabe Thiele Method)

A 150 moles of liquid mixture containing 60 mol% n-hexane (more volatile) and n-heptane is to be batch distilled at latm total pressure. The relative volatility of n-hexane in the mixture is 2.36.

i)If 50 moles is distilled, what is the average composition of the distillate and the composition of the liquid left in the still?

ii)If the accumulated vapor is 90% n-hexane, calculate the amount of distillate

1. What is an azeotrope? Give an example of azeotropic system. How an azeotropic mixture can be separated?

A thermometer follows first order dynamics with a time constant of 0.2 min. it is placed in a temperature bath at 100°C and is allowed to reach steady state. Its suddenly transferred to another bath at 150°C at time t=0 and is left there for 0.2 min. it is immediately returned to the original bath at 100°C. Calculate the thermometer reading at time t=0.1 min and 0.4 min.

b) A first order reactionA→B, with the rate constant k is taking place in CSTR fed with A at concentration Car which remains unchanged. There are likely to be some deviations in the feed rate (F) of A. Derive linearized transfer function between. concentration of A in the outlet and feed rate of A assuming that volume V of reacting mixture remains unchanged.

Explain feedback and feed forward control schemes with their differences.

c) A process of unknown transfer function is subjected to unit impulse input. The process output is measured accurately and is found to be represented by Y(t)= te^t.Derive unit step response of the process.