Internally Heated Dessicant Air Dryer Exhaust Pipe

[David Gin]

Hi all,

Is there a correlation between an Air Dryer capacity and the exhaust pipe diameter? How would a small exhaust pipe diameter (not able to exhaust air enough) affects the capacity of an air dryer? If it does, could you expand on this? Thank you

 

[CWatters]

What happens if the diameter is zero?

 

[David Gin]

What happens if the diameter is zero?

Heat won't be able to escape during regeneration phase as the desiccant is heated up for re-use.

 

[JBA]

As long as the maximum flow rate and and operating pressure do not exceed those specified for the selected dryer, any exhaust flow rate reduction will not have a detrimental effect on the dryer's performance.
In multi-use air systems, the flow in the systems continuously vary in accordance with the down stream equipment demands; but, as long as the dryer's rated capacity (scfm), and its maximum rated operating pressure are not exceeded there are no detrimental effects from those varying demand rates.

 

[David Gin]

As long as the maximum flow rate and and operating pressure do not exceed those specified for the selected dryer, any exhaust flow rate reduction will not have a detrimental effect on the dryer's performance.
In multi-use air systems, the flow in the systems continuously vary in accordance with the down stream equipment demands; but, as long as the dryer's rated capacity (scfm), and its maximum rated operating pressure are not exceeded there are no detrimental effects from those varying demand rates.

Hi JBA,
Appreciate your inputs. How about if the air dryer is not exhausted quickly enough due to the exhaust piping is design smaller than the required specifications, how would it affect the dryer capacity?
Thanks,

 

[JBA]

I think I need to get some clarification on what part of the drier cycle you are concerned about when you refer to the "exhaust piping" flow.

Under standard applications there are always times when there are no demands on the air supply output, so I am having a bit of trouble understanding exactly your issue about reduced flow rates through the drier.

 

[David Gin]

I think I need to get some clarification on what part of the drier cycle you are concerned about when you refer to the "exhaust piping" flow.

Under standard applications there are always times when there are no demands on the air supply output, so I am having a bit of trouble understanding exactly your issue about reduced flow rates through the drier.

That will be during the regeneration phase where heat is removed after the desiccant is heated.

 

[JBA]

So basically we are discussing the venting flow volume during that phase vs the time allotted by the dryer controller for that process, correct?

 

[David Gin]

So basically we are discussing the venting flow volume during that phase vs the time allotted by the dryer controller for that process, correct?

That's right, apologies for not being clearer earlier. Is there a correlation/explanation between the amount of air exhausted during this phase that would cause the air dryer to work at a reduced capacity?

 

[JBA]

At the same time I should have paid more attention to the "vent piping" part of your initial post.
OK, now that we are on the same page, I would expect that, at worst case, it might result in the dryer injecting some amount of heated air into the downstream plant air supply system when the dryer is cycled back online. Ultimately, this is a subject best discussed with the drier manufacturer.