1.Production of ethyl acetate in a batch reactor
A daily production of 50 tonnes of ethyl acetate nom alcohol and acetic acid is required. The reaction proceeds according to:
C2H5OH(A) + CH3COOH(B) → CH3COOC2H5(P) + H2O(Q)
The conversion rate in the liquid phase at 100°C is given by Smith [2]:
RA = k(CACB - CPCQ/K)
where k = 7.93 x 10-6 m3/kmol s and K = 2.93. The molar conversion rates of all components are equal because of the equality of the stoichiometric coefficients.
The feed solution contains 23% by weight of acid, 46% by weight of alcohol and no ester. The required relative conversion of the acid is 35 %. The density may be assumed to have a constant value of 1020 kg/m3. The plant must be operated day and night and the time for the filling, emptying and cleaning operations of a reactor is 1 hour, irrespective of its size. What is the required reaction Volume if (a) one reactor vessel, (b) three reactor vessels are to be used?
2. Same for a CSTR.
3. Same for a tubular reactor. Is there any advantage in using a PFR instead of a batch reactor.
4. Maximum load and optimum load in a batch process.
What is the maximum production load and the optimal load for the reactor in problem 1. Down period is 1 hr.
Cost during operation $2760/hr.
Cost during down period $900/hr.
Cleaning cost is $1040.
5. Consider a cascade of 3, 18 m3. For the same conditions of Problem 1, what is best to run the cascade or operate the reactors in batch mode?
6. Tubular reactor with varying density and pressure drop
In a tubular reactor with a length of 10m a gas reaction A → 3B takes place at a constant temperature of 350 K. The inner diameter of the reactor tube is 0.113 m, the molecular weight of A is 90. The feed consists of pure A and the reactor load is 15.5 kg/s. The inlet pressure is 5 bars (=5 x 105 N/m2) and the pressure drop along the reactor length is given by dp = 4f x 1/2 ρv2 x dz/d, and 4f= 0.025.
The gas mixture behaviour is ideal and RA = 3.21PA/RT. Calculate the conversion and pressure along the reactor length and give the densities and linear gas velocities at the inlet and .outlet of the reactor.
7. Start up of a CSTR
The conversion rate of A is RA = kcA kmoles/m3s. Before t = 0 the reactor is empty, from the moment t = 0 the feed is pumped into the reactor at a rate of Φv,m3/s and with a concentration of cAo, of the reactant. At t = T the liquid level has reached the overflow and after that the reaction volume V, remains constant. The mixing is ideal after t = 0. Calculate the concentration ca as a function of time
For t ≤ t no liquid leaves the reactor and the material balance leads to
8. Slow addition of reactant to reduce heat evolution
A batch reactor is filled with 2 m3 solvent. The reaction rate is given by RA - k4k, where k = 5 x 10-4s-1. A solution of 1 kmol A/m3 is added at a rate of 10-3 m3/s till the reactor is filled with 4 m3 reaction mixture. As the heat evolution is proportional to the reaction rate, calculate the reaction rate in the semi-batch reactor and compare it with the rate that would apply if the entire reaction mixture were put at once into the reactor, assuming that the reactors are kept isothermal.
The following rate data are obtained for the first order catalytic decomposition, A → R using 18 mm spherical catalyst particles (density of solid catalyst = 1000 kg/m3).
CA, mol/m3 0.01 100 5 1 0.1
= rA: mol/m3hr 30 270 100 400 110
T, K 400 286 303 345 370
C35 Determine the activation energy of the reaction and find the temperature regime where pore diffusion slows the rate of reaction for particles of this size.
C36 Develop an equation for the rate of reaction for any size of catalyst particle in the diffusion free regime. Express the rate in moles reacted/kg catalyst.s.
C37 Develop a rate equation for all sizes of catalyst particles acting in the strong diffusion regime. Let the reaction rate be expressed in moles/kgs and the particle radius R in mm.
C38 Develop the complete rate equation for all particle sizes and diffusion regimes. Give the reaction rate as moles/m3 catalysts, and the particle radius R in mm.