Patent ID: 7115202

Claim:
A method for separating a multi-phase mixture, into at least one liquid phase and one dry phase with a given dry matter concentration c TS using a decanting centrifuge which includes: (a) an annular immersion disk that is connected to a shaft at its inside circumference and that exhibits an outside diameter that is smaller than the inside diameter of a centrifuge drum; and (b) at least one liquor weir with a weir gap arranged at the end face of the centrifuge drum that can be used to draw the liquid phase from the centrifuge drum, and with a tank depth setting device that can be used to set the tank depth X T of the liquid phase that rotates in the centrifuge drum; said method comprising the steps of: (1) starting up of the centrifuge drum to a start-up drum speed n Z,1 , and setting the tank depth x T to a start-up tank depth X T,1 ; (2) introducing the multi-phase mixture into the rotating centrifuge drum; (3) drawing off the dry phase through the at least one dry matter discharge opening and drawing off the liquid phase through the weir gap; (4) controlling the tank depth x T corresponding to the dry matter concentration c TS in the drawn-off dry phase until a specified nominal dry matter concentration c TS,1 is reached, using the tank depth setting device; (5) specifying a tank depth tolerance range with a lower tank depth X T,U and an upper tank depth X T,O ; (6) comparing the adjusted tank depth x W with the tank depth tolerance range and continuing carrying out of steps (2) to (6) while the tank depth x T is within the tank depth tolerance range; (7) raising the centrifuge drum speed nz by a speed step value Δn Z at a tank depth x T that is smaller than the lower tank depth x T,U, or lowering the centrifuge drum speed n Z by a speed step value Δn Z at a tank depth x T that is greater than the upper tank depth x T,O ; (8) re-adjusting the tank depth x T corresponding to the dry matter concentration c TS in the drawn-off dry phase until it reaches a specified nominal dry matter concentration c TS,0 ; and (9) comparing the re-adjusted tank depth x T with a specified tank depth tolerance range and repeating steps (6) to (9) if the tank depth x T violates the tank depth tolerance range under continued feed of the multi-phase mixture into the rotating centrifuge drum and drawing off of the liquid phase and the dry phase.