Method for the separation of multi-phase mixture and decanting centrifuge system for carrying out said method

A method for separating a multi-phase mixture, into at least one liquid phase and one dry phase with a given dry matter concentration cTS 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 XT 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 nZ,1, and setting the tank depth xT to a start-up tank depth XT,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 xT corresponding to the dry matter concentration cTS in the drawn-off dry phase until a specified nominal dry matter concentration cTS,1 is reached, using the tank depth setting device;
• (5) specifying a tank depth tolerance range with a lower tank depth XT,U and an upper tank depth XT,O;
• (6) comparing the adjusted tank depth xW with the tank depth tolerance range and continuing carrying out of steps (2) to (6) while the tank depth xT is within the tank depth tolerance range;
• (7) raising the centrifuge drum speed nz by a speed step value ΔnZ at a tank depth xT that is smaller than the lower tank depth xT,U, or lowering the centrifuge drum speed nZ by a speed step value ΔnZ at a tank depth xT that is greater than the upper tank depth xT,O;
• (8) re-adjusting the tank depth xT corresponding to the dry matter concentration cTS in the drawn-off dry phase until it reaches a specified nominal dry matter concentration cTS,0;
• and
• (9) comparing the re-adjusted tank depth xT with a specified tank depth tolerance range and repeating steps (6) to (9) if the tank depth xT 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.