The use of Portable Dry/Convey units has to be weighed against Central Drying/Conveying to see which option is best for any given processor.
The concept of a drying system that can move from machine to machine actually developed with the processors themselves who modified equipment into portable devices.
Portable drying machines enable processors to:
- Install other auxiliaries on their machines
- Eliminate tall, potentially unsafe drying hoppers on machine throats
- Pre-heat material elsewhere, prior to actual processing at the machine
- Rapidly remove drying equipment from the machine for cleanout and material change
- Do cleaning and maintenance in other, better suited, locations
- Use drying equipment to be only when necessary, and to remove it at other times
All of these reasons make a great deal of sense if you are only doing occasional drying.
Central drying/conveying is the most efficient way to get materials to your machines if:
- You have dryers on 10 or more machines
- You have a single material that requires drying and it is required at multiple machines
- You have frequent material changes on your machines
- You use more material types than you have machines
- You have dryer to dryer quality issues when drying the same material
- You want to expand, but do not have sufficient space
Types of dryers available in portable models include:
- Desiccant Wheel Dryers
- Dual Bed Desiccant Dryers
- Compressed Air/Membrane dryers
These models include the Dryer, Drying Hopper with a Vacuum Receiver a Vacuum Pump, all mounted on a frame with casters. A Machine-Mounted Vacuum Loader or Receiver is also supplied to be mounted on the process machine throat. It is not practical to use them for throughputs above about 200 lb./hr. because the unit would simply be too large to push around the plant floor.
Controls have to be designed for both drying and conveying functions. Some microprocessor controls use various codes to describe errors and function buttons for programming parameters. There are also touch screen controls with intuitive icons and keypads for programming functions. With touch screen controls, errors are clearly spelled out in easily understood text messages. There are even controls that include features like over-drying protection for moisture-sensitive resins like nylons and photo-enhanced maintenance and trouble-shooting guides.
Some manufacturers charge extra for things like a warning light or a dew point analyzer, while others include those as standard.
