Apparatus and method in the treatment of the stock passed to a headbox of a paper machine or equivalent

An apparatus for treatment of stock passing to a headbox of a paper machine, comprising:

• a short circulation of the paper machine;
• a first stock chest;
• a hydrocyclone plant forming a part of the short circulation, the hydrocyclone plant connected to the first stock chest by a first stock transporting line, the hydrocyclone plant having an accept outlet line;
• a second stock chest having a second stock transporting line, wherein the accept outlet line joins the second stock transporting line to form a third stock transporting line which is connected in stock supplying relation to the headbox, and wherein the accept outlet line joins the second stock transporting line so as to mix stock flowing along the accept outlet line with stock flowing along the second stock transporting line;
• a mixing device between the first stock chest and the hydrocyclone, the mixing device forming part of the first stock line;
• a second mixing device where the accept outlet line joins the second stock transporting line to form a third stock transport line which is connected in stock supplying relation to the headbox;
• a first pump in the first stock line between the first stock chest and the first mixing device;
• and
• a second pump in the first stock line between the first mixing device and the hydrocyclone.

A method for treating stock passed in a short circulation to a headbox of a paper machine comprising the steps of:

• passing a first flow of stock to a hydrocyclone plant, and forming an accepts flow of stock;
• combining the accepts flow with a second stock flow which has not passed through the hydrocyclone plant in a mixing device to form a combined stock flow;
• and
• passing the combined stock flow to the headbox of the paper machine.

A method for reducing the energy used in a short circulation in a papermaking machine wherein a headbox is supplied stock from an inlet header and wherein the inlet header is supplied with stock from at least a first stock chest of stock which has not passed through a hydrocyclone and a second stock chest of stock which has passed through a hydrocyclone, the method comprising the steps of:

• cleaning stock from the first stock chest with a hydrocyclone to form an accepts flow of stock;
• mixing the accepts flow of stock with a flow of stock from the second stock chest in a mixing device to form a mixed stock;
• and
• supplying the mixed stock to the inlet header of the headbox.