Ultra Filtration System - E Coat

In electro coat paint system paint circulates through the ultra filtration unit.  The permeate passing through the membrane is either pumped to the rinse section and used as rinse water or diverted to drain.  The paint remaining in the modules is pumped back to the dip tank.

This is called as straight through paint circulation.  Paint is pumped from the dip tank, through the ultra filter, then back to the dip tank.

5. ULTRA FILTRATION SYSTEM DESIGN

The spiral wound system consists of modules arranged to operate in parallel.  The number of modules per system depends on the amount of permeate required in the design.  Each module is connected so that paint or cleaning solution flows through them from the inlet to the outlet manifold.  Permeate from each module is directed into a permeate manifold which can be directed to the rinse stages, storage, drain or clean tank.  Safety switches are provided which activate alarm and shut down ultra filter supply pumps in the event of high temperature or high-pressure conditions.

4. SPIRAL WOUND SYSTEM DESIGN

Paint feed is pumped to one end of the spiral assembly through the process inlet.  It then enters into the open space created by the feed flow channel spacer and flows down the length of the assembly and out the process outlet as concentrate.  The permeate passes through the membrane, collects in the porous media inside the membrane envelope, and flows in a spiral pattern towards the perforated permeate tube.  The permeate exits the module through the permeate outlet.

Spiral wound ultra filtration modules have been applied for many years on automotive cationic electro coat paint lines in India, Europe and Japan, as well as the United States.

The spiral module basically consists of flat sheets of membrane separated by a flow spacer.  These are wound around a permeate tube to form a cartridge.  This spiral wound module can withstand pressures in excess of 100 psig at ambient temperatures.  The spiral design is rugged, so it wont break or leak unlike other thin channel devices.  This eliminates the costly maintenance of removing and repairing leaking modules.  Spirals have a large membrane area and are compact in design.  They give more permeate for the amount of fluid passing through the module.

3. SPIRAL MODULE DESCRIPTION

1. ULTRA FILTRATION

Ultra filtration is a process for separating water from high molecular weight, colloidal and very fine solids materials by filtration through micro porous or semi permeable membranes.

This industrial process is used for removing water and dissolved salts from liquids flowing at low pumping pressure.  The key to the process is a thin, semi permeable, polymeric membrane that selectively retains large dissolved molecules or colloidal particles while permitting the passage of water, salts, solvents and other small molecules Ultra filtration is continuous, operates at low pressures and separates a solution into two streams, a concentrate and a permeate.

In electro coat paint systems, permeate produced by the ultra filtrations system contains water and paint solubilizers.  Permeate is used in the paint line rinse section.  This recycling method provides a closed loop rinse system for recovering paint drag out.  This permeate can also be diverted to drain to reduce the conductivity of the paint.  Concentrated paint is returned to the paint bath.

2. SPIRAL WOUND ULTRA FILTRATION

Process Description :