Which is the drawback of the plug flow reactor?

Which is the drawback of the plug flow reactor?

Disadvantages of plug flow reactors are that temperatures are hard to control and can result in undesirable temperature gradients. PFR maintenance is also more expensive than CSTR maintenance. Through a recycle loop a PFR is able to approximate a CSTR in operation.

What is plug flow in wastewater treatment?

A type of flow that occurs in tanks, basins, or reactors when a slug of water or wastewater moves through a tank without dispersing or mixing with the rest of the water or wastewater flowing through the tank.

What are plug flow conditions?

Plug flow therefore is a type of flow that satisfies the following criteria: The velocity profile in the direction of flow (axial) is flat and uz = u; There is no mixing in the axial direction; There is complete mixing in the radial direction.

Is there back mixing in plug flow reactor?

5.2 Plug Flow Reactor. PFR is an idealized flow reactor such that along the direction of the flow all the reaction mixture are moving along at the same speed; there is no mixing or back flow. The contents in the PFR flow like plugs, from inlet to outlet.

What are the advantages and disadvantages of using a plug flow reactor over other reactors?

Kinds of Phases Present Usage Disadvantages
1. Primarily Gas Phase 1. Large Scale 2. Fast Reactions 3. Homogeneous Reactions 4. Heterogeneous Reactions 5. Continuous Production 6. High Temperature 1. Undesired thermal gradients may exist 2. Poor temperature control 3. Shutdown and cleaning may be expensive

When would you use a plug flow reactor?

Plug flow reactors are used for some of the following applications:

  1. Large-scale production.
  2. Fast reactions.
  3. Homogeneous or heterogeneous reactions.
  4. Continuous production.
  5. High-temperature reactions.

What is plug flow activated sludge process?

A simplified activated sludge process (ASP) with one main dissolved substrate and one main particulate biomass component is analyzed with respect to its steady states. The ASP is formed by a plug-flow reactor (PFR) and a settler with recycling to the reactor. The biomass growth rate is described by a Monod function.

How do you ensure that the experimental conditions are plug flow in a plug flow reactor?

To ensure plug-flow conditions with a uniform velocity profile (u) over the catalyst bed such as displayed in Figure 3, ideal mixing in the radial direction and no mixing in the axial direction is required. Both these criteria can be evaluated with correlations from Mears et al.

Which is the disadvantage of batch reactor?

Engineering :: Chemical Reaction Engineering

[A]. high labour and handling cost Poorer quality control of the product
[C]. considerable shutdown time to empty, clean out and refill all of the above

Is there mixing in plug flow?

Plug flow operation is an alternative to mixed operation for continuous reactors. No mixing occurs in an ideal plug flow reactor; liquid entering the reactor passes through as a discrete ‘plug’ and does not interact with neighbouring fluid elements.

When do hot spots occur in a chemical reactor?

Hot spots may occur within reactor when used for exothermic reactions. Difficult to control due to temperature and composition variations. Ashe, Robert. “From Batch to Continuous Processing.”

What happens when a plug is placed in a nuclear reactor?

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.

What is a plug flow reactor?

Figure 1. This one need to be redrawn The Biofilm exercise collection contains several reactors that are of the Plug Flow variety. One very useful and instructive plug flow reactor is the Flow Cell . Flow cells have been used to investigate the growth of biofilms in real time on the stage of a microscope.

What is a tubular reactor used for in industry?

Common industrial uses of tubular reactors are in gasoline production, oil cracking, synthesis of ammonia from its elements, and the oxidation of sulfur dioxide to sulfur trioxide. Pictured below is a tubular reactor used in research on the oxidation of nitrogen compounds.