Process and apparatus for positioning replacement anodes in electrolytic cells

A process for replacing anodes in an electrolysis cell comprising a bus bar and at least one anode having an anode rod connected with said bus bar, comprising the steps:

• (a) calculating a desired distance (D4) from said bus bar to a reference point on or adjacent to an anode rod for a new anode to replace a spent anode in said cell, where the bus bar is chosen as an absolute reference for vertical positioning, said calculation comprising the steps:
• (1) measuring a first distance (D1) from said bus bar to a reference point on or adjacent to an anode rod for said spent anode,
• (2) measuring a second distance (D2) from a suitable location on or adjacent to a bottom of said spent anode to said reference point on or adjacent to said anode rod for the spent anode,
• (3) measuring a third distance (D3) from a suitable location on or adjacent to a bottom of said new anode to said reference point on or adjacent to said anode rod for the new anode, and
• (4) calculating said desired distance (D4) as follows:
• D4=D3−D2+D1+X, wherein X is a predetermined distance between said bottom for the spent anode and said bottom for the new anode,
• (b) replacing said spent anode with said new anode so that said reference point is spaced from the bus bar by an actual distance (D5),
• (c) measuring said actual distance (D5) by means of at least one laser distance detector associated with and sending signals to a programmable logic controller (PLC) which compares the actual distance (D5) with the desired distance (D4) and controls raising or lowering the new anode, and,
• (d) repeating step (c) at least once, to reduce the distance between the actual distance (D5) and the desired distance (D4) to an acceptable level.