Spray dryer safety systems maintenance is critically important. Spray dryers generally have fire and explosion safety systems. These are designed to protect the people and equipment from harm or damage in the event of a fire or explosion.
“Over the years, I’ve been part of too many accident investigations where a plant has a fire or explosion that cannot be put out or safely vented simply because of lack of testing or maintenance,” says Jim Kent, Caloris business development manager and spray dryer expert. “Fortunately no operators or plant staff were injured, but the interruption to the operation lasts weeks or months instead of just two or three days.”
The maintenance and testing of these safety systems ensures a safe working environment for your employees and reliability of your production line.
Maintenance of Dryer Safety Systems
One of the best ways to ensure spray dryer safety is to maintain safety systems for top performance. Properly maintained safety systems will help you get back online faster in case of an event.
Top Tip #1: Regularly test the system to identify and correct deficiencies. Maybe you can only test the electronics (instruments and solenoids) and not perform a complete test where the system completely activates. Usually there is a means to test all critical parts without activating the system. Whether you rely on Water Deluge, Explosion Suppression, Inert Gas Suppression or something similar, it should be tested on a regular schedule. You don’t want to learn about a failure of this system when you most need it to work.
Top Tip #2: A regular visual inspection of passive safety systems like Overpressure Vent Panels is vital. Do NOT bolt shut over-pressure doors, which may be tempting in the case of CIP leakage. DO NOT block panels or doors. There needs to be an escape route for pressure, otherwise, the only route for pressure venting will be back into your facility.
More on Overpressure Vent Doors & Panels
Shear pins must be maintained (they are designed to open at a certain pressure) — do not replace these with bolts, which will impede proper door function.
Gaskets must be maintained/replaced when necessary — don’t use caulk, which does not have the same functionality.
Spring hinges must be maintained as well.
Water Safety Systems for Over-temperature Protection
- Test these systems regularly (air, water pressure, test panel, pneumatics, water valves, etc.)
- Test the chamber and fluid bed with every CIP (~ 3 months)
- Test bag filters with every bag change
- Test air and water pressure switches
- Visually check that all hand valves remain open
- Maintain documentation
- Maintain battery backup
- Maintain stock of spare parts
- Maintain relays and switches
Environmental & Nuisance Dust
Dust around a spray dryer is often inevitable, but how much dust is acceptable in your dryer room before you feel in danger? A layer of 1/16 inch or 1.5mm is a problem. This very small amount of dust in the room or settled onto the outside of equipment, when raised through concussion of an explosion inside of the equipment, creates a dust cloud and is enough to fill a room to explosive levels
Other Recommendations for Dryer Safety Systems
There are other more advanced safety systems and practices that might provide better, earlier or more sensitive detection of smoldering, fires or explosions before they become a problem.
Caloris recommends carbon monoxide detection for spray drying systems. CO is often produced by combustion and can be measured. This is a new technology for spray dryers, but is a good preventive measure to take and provides advance warning to safely shut down the plant and investigate.
If you use high pressure nozzle atomization in your spray dryer, nozzle testing is another best practice to institute. Ninety percent of all process, product quality and safety problems start with the nozzles. Cameras can monitor the nozzles after they are in production, but wouldn’t it be better to catch an improperly assembled nozzle before it is installed? Test nozzles under pressure in a nozzle lance test station before you install them in the dryer. You can have multiple sets of nozzle lances ready to go. Problems can come from incorrect assembly and worn parts.
Spare Parts to Have On-Hand
Over-pressure panel doors can take 4-6 weeks to procure, if a replacement is needed. These generally have a two-year cycle before they need to be replaced.
Single-use rupture panels weaken over time. In addition to posing a safety risk, they also present a hygiene problem, due to possible leaks.
Have a Question?
Contact Caloris today for assistance with your spray dryer safety systems. Call 410-822-6900 or send email to problem.solved@caloris.com to be connected with a dryer specialist.
Did you miss our previous post on holiday staffing? Read it here. Also, be sure to watch our archived webinar on Spray Dryer Safety, if you haven’t already. This resource is available for you to share with your colleagues and staff.
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