Fan upstream or downstream of a scrubber

This is case specific. To get useful replies, you should describe your case in detail.

Hi,
A google search.
Pierre


In a wet scrubber system, the fan can be located either upstream or downstream of the scrubbing column. Placing the fan upstream can help reduce the fan's exposure to corrosive or dirty gases, while downstream placement allows for greater flexibility in system design and better operator working conditions.

Upstream Fan Placement:

• Pros:
  The fan handles cleaner, cooler gas, potentially prolonging its lifespan and reducing maintenance needs.
• Cons:
  The fan may need to handle higher gas volumes and potentially higher pressure drops due to the scrubber's resistance. This can increase energy consumption.
  

Downstream Fan Placement:

• Pros:
  The fan handles a smaller volume of gas (after some of the pollutants have been removed by the scrubber) and potentially lower temperatures and pressure drops, potentially reducing energy consumption.
• Cons:
  The fan may be exposed to corrosive or dirty gases, leading to increased wear and maintenance.
  

Additional Considerations:

• Scrubber Design:
  The scrubber's specific design (e.g., packed bed, spray tower) can influence the optimal fan placement.
  
  
• System Requirements:
  The overall system requirements, including gas flow rate, pressure drop, and desired efficiency, will also factor into the decision.
  
  
• Flexibility:
  Downstream placement offers more flexibility in terms of system layout and access.
  
  
• Safety:
  For systems handling hazardous or corrosive materials, upstream placement might be preferred to protect the fan.

pierreick said:

Upstream Fan Placement:

• Pros:
  The fan handles cleaner, cooler gas, potentially prolonging its lifespan and reducing maintenance needs.

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Pierreick,

Did you write this or is this a Google AI summary? This looks like AI garbage. If this is a re-post of a google search, like you alluded to, please refrain from posting such nonsense on these forums. It is clear that AI has a long way to go before being able to be relied upon for "sound engineering judgement", and this post is either actively incorrect on a few critical points, or is 100% confident on a point which actually may change based on the process.

Case-in-point from the quote above:

I don't see how placing a fan upstream of a scrubber protects the fan from dirty or corrosive gases, since those have yet to be scrubbed out by the wet scrubber. The only time I could see that a fan upstream would be exposed to a less corrosive environment (i.e. for acid gas streams) is if there is essentially no moisture content in the gas stream, meaning acid gases would not be corrosive, whereas downstream of a wet scrubber the un-scrubbed acids, mixed with humidification by the scrubber, may be corrosive. Gases upstream of a scrubber tend to be hotter (often from combustion processes), wet, and dirtier, as they have yet to be scrubbed/quenched by the wet scrubber.

"

Flexibility:
Downstream placement offers more flexibility in terms of system layout and access."

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What does this even mean? Plant equipment layout and access doesn't care if the fan is upstream or downstream of the scrubber. You can have great, or poor, access in either configuration.