Continuous separation system

Abstract

A continuous separation system which continuously purges, washes, dries, and removes solids with a minimum amount of mechanical handling and consequential crystal breakage. A separator within the continuous separation system of the present invention comprises a stationary casing, a horizontal rotary screen within the casing, a fixed scraper mounted in the casing above the screen, an inlet conduit on one side of the scraper for depositing slurry on the screen to form a layer as the screen rotates, an outlet conduit on the other side of the scraper for carrying away dried solids, and gas nozzles for directing a gas stream at the solids as they encounter the scraper, entraining them, and directing them through the outlet conduit. The screen divides the casing interior into respective upper and lower chambers that are sealed from one another except through the screen. In operation, the gas stream carries the entrained solids to a separate receiver. The gas is then recirculated and enters the upper chamber of the separator at a slightly positive pressure. The lower chamber is evacuated so that a portion of the gas in the upper chamber passes through the slurry layer to displace liquid through the screen while further amounts of the gas cause additional drying of the solids so that they are of a suitably low liquid content when they encounter the fixed scraper and are entrained out of the separator.