Condensate issues!

[infineum]

Your problem is definately more of a mechanical issue rather than controls. The suggestion to raise the temperature of the system is probably the best. However, if your plant is not air conditioned, this senerio will not work during the summer since the dewpoint will be high. The recirculation loop that you speak of, I am guessing, is rather large therefore it will take some time for the loop temperature to rise due to heat generated from pumping and insulation losses. Anything that you do to raise the temperature during recirculation such as an external heater will result in longer startups since my guess is that chilling is essential to the process. The only other viable alternative is to actually shut recirculation when the machine is not running. The system will heat somewhat during the downtime and will require some delay during start-up. But this senerio is possible with the system as designed.

 

[Christoph]

your correct, plant is not air conditioned. temps outside have been
running mid 90s F. The rolls are about 175 feet away from the circ pump
and control valve. All are located on a mezzanine on 3rd floor height,
with the rolls at ground level. Pulling up RSLogix now and checking
the pump control code.

 

[leitmotif]

OK so you have this chilled roller supplied by a loop using a 3 way valve to control temp of the water leaving the roll.
When shut down chilled water flowing thru roll is causing condensation.
FIRST thought - why is 3 way valve not fully shutting off flow thru roll? IF the valve is leaking by when supposedly fully shut you can play with controls all day long and not do a thing.
IF you have this much piping turning off the pump will drive production mad the poor dears may have to wait until the chiller can cool down the entire loop and roll before starting up.
OPTIONS
1. Fix or get 3 way valve that can completely shut off flow to the roller.
2. Add another valve to shut off flow to chiller
manual? BUT then the operator needs to remember to open it.
automatic you could sense some roll parameter (ideally one you are already sensing) such as motor current. When that value falls to say one amp (for drive motor) then shut the shut off valve. You could also do it off the on off switches for the motor. They will still have to wait until the roll cools down to start but that is what happens when they do not want to spend money on properly designed and installed equipment.

Best of luck

Dan Bentler