Case History:
Paint De-Tack Program Using Centrifuge As The Solid Removal System
ACCOUNT: International Truck & Engine Corporation - Melrose Park, Illinois
Manufacture Diesel Engines
PAINT TYPE: water base paint using water miscible solvents.
PAINT LOAD: Spraying 100 gallons of paint per day.
TRANSFER EFFICIENCY: 50%
Design:
- Very old recovered downdraft paint booth built by George Koch & Sons. Manifold
pipes delivered water spray to the eliminators using fan spray jet style nozzles. Sump is a
rectangular shape with side extensions and a flat bottom. It's located directly below the
floor grates.
- Vertical re-circulating pump installed in a pump well box attached to the side corner
of the sump tank. The water draw to this pump came from the area near this corner. No
other sump agitation was present. Most of the water in this sump was "quiet".
- Lacked any paint recovery system.
- Started with a manual spray operation painting 230 engines per day and later investing
in robots that increased production to 300 engines.
Problems:
- Water-based paint saturating in booth water.
- Manifolds constantly plugging up with paint solids with a heavy sludge build-up in the
sump pan.
- Exhaust stacks and fans blocked up with paint solids. It was so severe that they had
to cut bypasses in the roof exhaust stack before the fans to relieve the overload.
- High production levels limited the maintenance time on the booth, however the stacks
and fans were being cleaned once per week, and the sump was being manually shoveled
out every three to four weeks.
- Once the retrofit designs were in-place and an automatic centrifuge system was
installed, our competition implemented the wrong paint kill program for this system and
no paint solids were being removed.
Solutions:
- Modified the booth pans to eliminate "dead areas" of booth water agitation.
- Mass water flow system was designed below water surface in sump pan to "drive" the
suspended paint particles to the centrifuge pick-up point.
- High efficiency manifolds with less clogging spray nozzles installed.
- Main booth exhaust fans were upgraded.
- An automatic centrifuge was installed only to be upgraded to a more efficient one
when increased engine production added excess solids to the system.
- Replaced our competitor's polymers with our paint kill polymer program and
immediately started to remove paint solids from the booth water. Utilized the proper
polymer for charge neutralization, which broke the paint molecule from the water and
coagulated it into the proper micron size for the centrifuge to catch.
Results:
- Clean out of sump only scheduled once per year.
- Exhaust fans, stacks, and both manifolds are remaining sludge free.
- Successfully removing paint solids, generating one drum of dry landfillable solid waste
every day and a half.
- Very little maintenance time (clean-ups) devoted to downdraft paint booth. Only
maintenance is floor grate, robot and good quality preventative maintenance.
- One of our most successful endeavors to date.