PMF Media FILTERSPMF filters are custom designed to meet the unique criteria of for clarifying application. Extensive lab trials and Pilot studies are carried out to optimize the PMF system. The filter consists of air and liquid distributor, supports, sight and light glasses, safety disc, air vents, pressure transmitter, isolation valves necessary piping and fittings etc. media bed including support media and filter media.
The CLOSED-LOOP PMF media filtration system is a unique system of automatic filtration, which is self-cleaning and specially designed for polishing applications. The filtration cycle starts with our proprietary media filters trapping suspended solids from the liquids. The PMF systems can be made from capacities ranging from as low as 10 M3/hour to as high as 250 m3/hour and then modular systems can be placed in parallel for higher capacities. As the filtration process continues the pressure drop across the filter determines the regeneration cycle.
The pre-set differential pressure automatically starts the regeneration cycle of the PMF system. The uniqueness of the system is that we do not use any extraneous cleaning fluids to regenerate and clean the PMF, but the filtered liquid is used for regeneration and sent back to the system thereby avoiding loss of product, without causing any dilution due to water cleaning, which is typically the case in other filter systems.
The major advantages of PMF Pressure Media Filters filtration:
- PMF System is Regenerable, requiring no consumable filter media like cloth, meshes etc. with complete automation, sequencing control panel with process logic controllers
- PMF does not generate any water; filter bed is generated without using any water or extra cleaning fluids. So no additional load on evaporators.
- PMF filter Media has a very long life.
- PMF has very low operational cost
- PMF system can be fully automated and hence no manpower is required, with hassle free performance - Easy to use operation
- PMF system gives a very high throughput, un-parallel by any other filtration system.
- PMF system gives particle retention as low as 5 micron and turbidity as low as 5 NTU
- No heat loss, due to very short retention times and full insulation
- Specific solid loading up to 25-30 Kg/m2
- Average TSS of up to 100 mg/l or greater
- Average filtration rates up to 20-25 m3/m2/hour.
The unique advantage of PMF media is the retention of solids, trace fibers and waxes throughout the bed, rather than the surface screening, which occurs in most filter systems. PMF pressure filters media allows solids to penetrate the bed surface and become entrapped through the full depth of the filter media below. PMF systems are designed, fabricated generally in accordance with ASME code.
Independent means for backwash water and air to enter the filter for superior backwashing capabilities.
The main factors influencing the filtering and trapping processes are:
- Suspended particle size: Filtration efficiency improves with larger particulate size.
- Pore size: The void space between the media determines the size of particulate that can be trapped. The media has been carefully selected based on the lab and pilot plant studies.
- Filtration velocity: Filtration efficiency decreases with increased velocity. Optimising the face velocities is a very important factor in determining good filterability.
- Temperature of liquid: Advantage is taken of high temperature of the sugar juice to improve filter efficiency.
The liquids are filtered through PMF and very fines and mud carryover (if any) is trapped in these. The internal hydraulics are carefully designed to maximize fines retention. The Graded media of the PMF system is the key to effective filtration and trapping of particles.
The complete filter is insulated ensuring minimal temperature drop in the liquid streams. The liquids are continued to be filtered further processing at a constant flow rate. Slowly there is a pressure build up in the system and then the system goes into an automatic regeneration cycles.
The regeneration cycles are determined on actual optimizing in the plant. Normally the system goes into a regeneration cycle after achieving a specified pressure drop. The system closes the inlet valve from the main feed tank and filtered liquid (filtrate) is sent back through the back-wash valves. During backwash the filter media expands to release the impurities, entrained in the filter media, which subsequently are washed out to the main feed tanks. Making it a closed loop system with NO INTRODUCTION OF WATER which would otherwise dilute the liquids.
Air bubbling is carried out to assist in filter media regeneration and clearing the trapped particles.
On completion of regeneration cycle the filter bed needs to resettle prior to effective filtration. Hence a rinse valve is provided which allows the inlet liquids from over the PMF back to the feed tank prior to commencing the filtration cycle