There are three process zones to a Belt Filter Press, the gravity zone, wedge zone, and high/pressure/shear zone. First, the gravity zone is where the sludge or slurry is first introduced to the filter. This typically happens after a chemical flocculent or polymer has been introduced and mixed into the slurry to release water and form larger particles. Finally, the slurry is spread across the usable area of the filter and is contained from running off the filter sides by rubber seals. There are typically plows or chicanes on the upper surface of the filter belt to move the sludge solids and promote drainage. On the lower side, the filter belt is typically supported by a grid of replaceable plastic material.
While many Belt Filter Press designs place these support grids too far apart (6-10 inches) and on some, the supports are also are too wide and block the drainage of liquids from the filter belt. However, Bright’s superior design places ½ inch wide UHMW plastic strips on 2.5-inch centers. As a result, this promotes superior drainage by breaking surface tension on the filter without unnecessary blockage of the exiting water. In addition, the close grid also better supports the filter, as a result creating a better seal with the rubber containment pieces.
INCLINED GRAVITY ZONE
Second, unlike most competitors which have a level gravity zone, Bright Belt Filter Presses feature an inclined gravity section. The sludge feed box is lower than the discharge end of the gravity zone. Therefore, this promotes better dewatering by keeping the water laden sludge back by the feed box and carrying the solids up to the discharge only after a majority of water has drained through the filter. As a result, this gives the gravity zone more effective dewatering time than is possible with a level gravity deck. It also makes higher production rates possible.
PATENTED WEDGE ZONE
Third, the wedge zone is where the upper and lower filter belts meet and envelope the slurry on two sides. As a result, Bright Technologies Belt Filter Presses have a patented radius wedge zone that applies a gentle pressure on solids in the slurry that provides superior conditioning prior to entry to the High Pressure/Shear Zone, and does not require any operator adjustment.
HIGH PRESSURE/SHEAR ZONE
Finally, in this zone the filter belts are wrapped around steel rollers that progress from large diameter to smaller and as the diameter of the roll decreases the pressure on the sludge increases. The first pressure roll on a Bright Belt Press is a patented fabricated roll called a wing roll; because this roll features a 50% open area and convex inner surface that channels the liquid to outside of the roll so that it drops beyond the filter belt and does not re-wet it. Also, our rolls are triple stub plate design and constructed of stainless steel so that no roll coatings are required.