Image Number 5 for United States Patent #7089681.
The present invention relates to a method and apparatus for filtering and drying a product. In a preferred embodiment, the apparatus comprises a container having a plurality of porous walls and a plurality of solid walls that divide the container into a plurality of product chambers, a plurality of vacuum chambers, and, preferably, a plurality of heat transfer chambers. Each product chamber shares at least one porous wall with an adjacent vacuum chamber. Each product chamber preferably shares at least one solid wall with an adjacent heat transfer chamber. According to the method of the present invention, a product is introduced into the product chambers, where the product is held while a substance is filtered from the product through the porous walls and the product is dried by reducing the pressure in the vacuum chambers and the product chambers. In a preferred embodiment of the method, a heat transfer fluid flows through the heat transfer chambers to facilitate keeping the product frozen and/or to facilitate faster drying of the product.