Desiccant dryer problems

[tj83]

Our plant has heated desiccant dryers for instrument air. The desiccant comes in small spheres but is disintegrating into powder and clogging the after filters. Heating elements are failing due to corrosion of the tube shields. How are these two problems related?

 

[quark]

Fines release and corrosion are not related. If the desiccant media is too old (say, 5 years or so), then it is right time for replacement. If the media is new but the fines release is significant then you may have high superficial velocity (i.e empty vessel velocity)

 

[dcasto]

It sounds like free water could have entered the dryers. This would account for the degredation of the beads early (if they are less than a couple years old) and the corrosion.

 

[chief]

Consider fitting a Cyclone separator at the compressor outlet. This will reduce moisture vapor carry-over by approx 98% and reduce the loading on the desiccant driers. Wright-Austin are the makers of these cyclones, also ensure you fit an auto drain on the cylone to dump collected moisture.

 

[ihg]

Dessicant disintegration and corrosion both point to liquid water contacting the drier. I assume that you have an aftercooler on the compressor; investigate if the autodrain is plugged (indeed, check if you have one!). It should be discharging an appreciable amount of liquid water, as about 6/7 of the water in incoming air should drop out on cooling back to near ambient temperature. The dessicant drier isnt designed to take liquid water.

 

[toothless]

Also check on your pressurization and depressurization times. Some dryers pressurize and depressurize very quickly, and I do not believe this is "healthy" for the desiccant.

 

[tj83]

Thanks for all input. Very helpful.