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Reactor Design

Reactor Design. Plug Flow Reactor (PFR). Plug flow reactors, also known as tubular reactors, consist of a cylindrical pipe with opening on each end for reactants and products to flow through. Reactants are continually consumed as they flow down the length of the reactor.

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Reactor Design

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  1. Reactor Design

  2. Plug Flow Reactor (PFR)

  3. Plug flow reactors, also known as tubular reactors, consist of a cylindrical pipe with opening on each end for reactants and products to flow through. Reactants are continually consumed as they flow down the length of the reactor.

  4. What is the meaning of the plug flow?

  5. Plug flow:ideal state of flow where for a “plug” of material there is no radial variation of concentration.

  6. The movie on the left shows the operation of a plug flow reactor. Plugs of reactants are continuously fed into the reactor from the left. As the plug flows down the reactor the reaction takes place, resulting in an axial concentration gradient. Products and unreacted reactants flow out of the reactor continuously.

  7. PFR Design Equation If “A“ is the limiting reactant:

  8. Sheet 3

  9. The reaction: is carried out in a PFR, if k = 1 sec-1, the concentration of A in feed is 1 gmole/lit, volumetric flow rate is 5 lit/sec, reactor cross sectional area is 50 cm2, and conversion is 80%. Find the concentration at the middle of the reactor.

  10. The aqueous phase reaction: has a rate equation: r = k CA CB with rate constant k = 500lit/gmole.min. It is to be affected in a tubular plug flow reactor under the following conditions: Volume of reactor = 0.1 liter Volumetric flow rate = 0.05 lit/min CAf= CBf = 0.01 gmole/lit • What would be the expected conversion? • For the same flow rate and conversion, what size of CSTR is required? • For the same flow rate, what conversion can be expected in a CSTR of size equal to that of PFR?

  11. The elementary liquid phase reaction: is carried out in a PFR. The entering concentrations of A and B are both 2 gmole/lit. and the specific reaction rate is 0.01 dm3/gmole.min. Assuming a stiochiometric feed (10 gmole A/min): • Calculate the reactor volume and space-time to achieve 90% conversion. • Redo (i) assuming the reaction is first-order in B and zero-order in A with k = 0.01 min-1. • Assume the reaction is reversible with Ke = 2 dm3/gmole. Calculate the volume of the PFR necessary to achieve 90% of the equilibrium conversion. (kf = 0.01 dm3/gmole.min.)

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