Centrifuge having axially movable scraping assembly for automatic removal of solids

A method for separating a fluid in a centrifugal separator, comprising the steps of:

• (a) rotating an elongated separator bowl and a scraper assembly and shaft spindle disposed therein about an axis at a high separating speed, said scraper assembly including a plurality of scraper blades extending substantially to an interior surface of said separator bowl, said scraper blades having a scraping width in the direction of said axis substantially less than the length of said separator bowl in the direction of said axis;
• (b) introducing a fluid to be separated into said separator bowl;
• (c) engaging said scraper assembly and said shaft spindle to prevent rotation thereof;
• (d) while said scraper assembly is engaged, rotating said separator bowl at a scraping speed substantially less than said separating speed;
• and
• (e) while said separator bowl is rotating at said scraping speed, axially moving said scraper assembly and said shaft spindle within said separator bowl to scrape solids that have accumulated along said interior surface of said separator bowl with said plurality of scraper blades.

A method for operating a centrifugal separator having a tubular separator bowl and an internal scraper assembly, said tubular separator bowl and said internal scraper assembly disposed for rotation about an axis of symmetry thereof, said method comprising the steps of:

• (a) draining liquid from said separator bowl, including the steps of
• (i) positioning a residual liquid container beneath a discharge port in said separator bowl to receive liquid drained from said separator bowl, and
• (ii) braking the rotation of said separator bowl and said internal scraper assembly;
• and
• (b) scraping solids accumulated on an interior surface of said separator bowl into a solids receiving container, including the steps of
• (i) moving said residual liquid container away from said discharge port whereby said solids receiving container is positioned to receive the scraped solids from said discharge port,
• (ii) engaging a scraper clutch so that said internal scraper assembly does not rotate with respect to said separator bowl,
• (iii) rotating said separator bowl while said scraper clutch is engaged, and
• (iv) while said separator bowl is rotating, moving said internal scraper assembly with respect to said separator bowl along said axis of symmetry.