Patent ID: 6754978
Filing Date: 2004-06-29
Classification: F26B

Abstract:
A method of vacuum drying sludge or slurry input material, comprising the steps of:providing a chamber that is horizontally elongated between first and second ends with at least two elongated augers as well as one and another transfer arrangements; providing the chamber with an interior bed portion that is recessed with at least two adjacent troughs separated by a low partition and is sized and arranged for accommodating the at least two augers in closely-spaced generally-horizontal side-by-side relation, wherein the augers extend between the chamber's first and second ends such that one auger defines a primary run for motivating material from the first to the second end as the other auger defines a return run for motivating material back from the second to the first end; providing the second end of the chamber with the one transfer arrangement for transferring material in the primary run motivated up thereagainst to go over to the return run, and providing the first end with the other transfer arrangement for transferring material in the return run motivated up thereagainst to go back over to the primary run whereby material re-circulates in the primary and return runs in an endless loop; given a source for suctioning, suctioning a current of carrier gas into the chamber by introduction through in-let nozzles and suctioning out a composite of let-in current and fractions of the material through suction ports such that an evacuated pressure in the chamber is achieved down to or below essentially &frac45;ths an atmosphere; introducing the sludge or slurry input material into the chamber for re-circulation in the primary and return runs with an air-lock device for preserving the evacuated pressure; given a source of heat, applying heat to the chamber or at least the bed portion thereof and optionally pre-heating the introduced material and let-in carrier gas to achieve a mean temperature inside the chamber up to or above essentially 75Â° C.; providing each auger with spaced flights on the screws thereof to form cut-and-fold arrangements therewith to agitate the material and driving the augers to counter-rotate relative each other to adapt each auger for lofting portions of the agitated material at the other over the low partition therebetween; wherein the effects of heat, evacuation, agitation and current through the chamber causes the input slurry or sludge material to disintegrate into fractions comprising gasified fractions, waftable finely divided particulate fractions, other waftable fractions and, depending on the input material, in some cases irreducible heavy or sticky fractions whereby the flowrate and introduction of the carrier gas is selected to substantially mix with or entrain the gasified, waftable finely divided particulate and other waftable fractions and carry such out through the suction ports.