Short circulation

The short circulation is a term used describing the process flows around a paper machine. By the short circulation is meant the flow loop from the wire tank, through pumps and cleaning
systems, to the headbox and back to the wire tank.

In the short circulation the stock from the machine chest is diluted. The dilution is done before the fan pump with water from the wire tank.

The wire tank is the chest where the white water is collected when the stock is dewatered on the wire. The level in the wire tank must be constant. The constant level is obtained as some of the white water always spills over.

The reason why there is always a water surplus in the short circulation is that the stock in the machine chest has a consistency of 3 to 4%. When the paper web then leaves the wire it has a
consistency of about 20%.