Method and apparatus for multi-NIP impulse drying

#The present invention generally relates to the dewatering of solid-liquid matrices. More particularly, the invention provides a continuous process for removing water from various types of solid-liquid matrices, including various types of sludge, with the simultaneous application of both pressure and heat to the solid-liquid matrices.

#Solid-liquid matrices from municipal, industrial and other processes are currently dewatered with a room-temperature belt, filter or screw press. These pieces of equipment employ high-pressure processes during which the water is separated from the solid-liquid matrices.

#An energy efficient means to dewater a solid-liquid matrix is through the use of impulse drying. “Impulse drying” occurs when a wet paper web passes through the press nip of a pair of rolls, one of which has been heated to a high temperature. A steam layer adjacent to the heated surface grows and displaces water from the wet sheet of paper in a more efficient manner than conventional evaporative drying.

#FIG. 1 illustrates the continuous impulse dewatering system of the invention.

#FIG. 2 is an expanded view of nip 80 located between upper heated roller 60 and lower cold roller 70 and further showing conveyor belt 10, liquid-solid matrix 50 and mesh 40.

#FIG. 3A illustrates a mesh 40 useful in carrying out the process of the present invention.

#The processes of the present invention are an improvement over currently-employed methods for dewatering solid-liquid matrices, including sludge, which generally consist of the pressing of the solid-liquid matrices with a room-temperature press (i.e., dewatering the solid-liquid matrices by squeezing the water therefrom by the application of a great amount of pressure). The processes of the present invention advantageously have been shown to significantly increase the amount of water being removed from certain solid-liquid matrices in comparison with the dewatering of the same solid-liquid matrices by the currently-employed methods for dewatering solid-liquid matrices.

#Definitions

#For purposes of clarity, the terms and phrases used throughout this specification and in the appended claims are defined in the manner set forth directly below.