Advantage and Disadvantage of Reactor Types

a) Tubular Flow Reactors

Used in large scale applications especially gas phase reactions.
Used for fast homogeneous and heterogeneous reactions
Suitable for continuous production and high temperature reactions.

source: https://www.tandfonline.com/doi/full/10.1080/00194506.2024.2328570

Advantages:

• Highest conversion per unit volume.

• Low operating labour costs

• Continuous operation

• Good heat transfer

Disadvantages:

• Undesired thermal gradients may exists, hence poor temperature control

• Shutdown and cleaning can be expensive
  
  

b) Tubular Fixed Bed Reactor

Suitable for gas phase solid catalyzed reactions i.e., gas-solid reactions.

source: https://www.researchgate.net/figure/Multi-tubular-fixed-bed-reactor-design_fig3_387160903

Advantages

• Highest conversion per unit mass of catalyst

• Low operating labour cost

• Continuous operations 

Disadvantages:

• Undesired thermal gradients may exists, hence poor temperature control.

• Channeling may occur. This is caused by uneven or loose packing of solid phase material inside the column meaning liquid flowing experiences less resistance hence higher flow rates. The liquid thus passes through voids within the bed rather than having contact with the packed material. This lowers the performance of the column.

• It is difficult to service and/or clean the unit.
  
  

c) Batch Reactors

Used in small scale productions e.g. laboratory processes. Widely used in pharmaceutical and fermentation processes.

source: https://www.essentialchemicalindustry.org/processes/chemical-reactors.html 

Advantages:

• High conversion per unit volume for one pass

• Flexibility of operation. The same reactor can be used to produce one product at one time and another product in the next time.

• Easy to Clean

Disadvantages:

• High operation costs i.e. labour costs

• The quality of the product varies as compared to continuous operations

d) Semi-batch Reactor

Suitable for small scale production. 

Two phase reactions like gas-liquid reactions can be carried out. 

source: https://chemicalengineeringworld.com/types-of-reactors/

Advantages:

• High conversion per unit volume for one pass.
• Good selectivity. The feed can be controlled to minimize side reactions.
• Flexibility of the operation can be used with a reflux condenser for solvent recovery or bubble type reactions. 

Disadvantages:

• High operation costs i.e. labour costs.

• The quality of the product varies as compared to continuous operations

e) Continously-stirred Tank Reactors (CSTR)

Suitable for liquid phase, gas-liquid, solid-liquid reactions

source: https://www.comsol.com/blogs/simulating-an-ideal-stirred-tank-reactor-system

Advantages:

• Continuous operation

• Good temperature control

• Easily adaptable to two phase (gas-liquid) reactions

• Reaction control is possible

• Easy to construct

• Low labor costs

• Easy to clean

Disadvantages:

• Lowest conversion per unit time

• By-passing channeling is possible with poor agitation. 

f) Fluidized Bed

Suitable for gas-solid reactions and gas-solid catalyzed reactions

source: https://www.sciencedirect.com/science/article/pii/S136403211930797X

Advantages:

• Good mixing

• Good uniformity of temperature

• Continuous regeneration of the catalyst by using an auxiliary loop.

Disadvantages:

• Bed fluid mechanics not well known

• Severe agitation can result in catalyst destruction, dust formation and carry over in product streams

• Uncertain scale up