Patent ID: 7448317
Filing Date: 2008-11-11
Classification: B01D,B30B

Abstract:
1. A method of operating a filter press for solid-liquid separation of a product consisting of a liquid containing solids, the filter press comprising a press jacket, a press plate at one end of the press jacket, a ram in the press jacket and movable relative to the press plate, and a plurality of flexible filter drainage elements installed between the ram and the press plate, the press jacket, the press plate and the ram defining a pressing space having a volume, the method comprising the steps of: preparing the filter press by loading the product to be pressed in the pressing space and by positioning the ram in a start position where the product only partially fills the pressing space; advancing the ram, during a first phase of a forward movement of the ram, from the start position to a full contact position which is positioned between the start position and the press plate, wherein the volume of the pressing space becomes equal to a volume of the product in the pressing space at the full contact position, the ram exerting no pressure on the product during the first phase of the forward movement to press liquid phrase out of the product; and advancing the ram, during a second phase of the forward movement, toward the press plate from the full contact position, the ram exerting pressure on the product during the second phase of the forward movement to press liquid phase out of the product, wherein, during the second phase, the ram is advanced from the full contact position at a full contact forward velocity which is lower than an average forward velocity averaged over the first phase of the forward movement, and wherein the first phase begins at a first time point and ends at a second time point when the ram reaches the full contact position, and wherein, beginning at the second time point, the ram is advanced from the full contact position at a full contact forward velocity which is lower than the average forward velocity during the first phase.