HD & LD cleaning - process info
Pulp dissolving (Waste paper), HD and LD cleaning
The pulp dissolving system of waste paper consists of a Pulper Dilution Tank, a high consistency batch pulper, dump screen, pump and a DIP Dump Chest.
The waste paper will be loaded on a conveyor and transported to the batch pulper. The conveyor includes a scale to measure the correct amount of waste paper to the pulper. White water to the pulper will be supplied from an elevated Pulper Dilution Tank. The volume of this tank is chosen so that it can be filled at a moderate pace and the elevated location will allow dumping to the pulper by gravity.
White water from this tank will also be used for consistency control when pumping the dissolved pulp to the DIP Dump Chest. The supply of white water to the Dilution Tank will be partly from the DIP Cloudy WW Tank and partly filtrate from the reject flotation unit.
The concept is to use reject flotation filtrate to an extent that no fresh water has to be added to the DIP plant white water system.
The pulper will operate at a consistency of 18%. When dumping the pulp will be diluted to 4,5%.
In order to remove bigger impurities a dump screen will be located between the pulper and the DIP Dump Chest. The dump screen will be intermittently flushed with white water to the rejct handling system. The first cleaning step following the DIP Dump Chest will be a combined HD and LD cleaning system. Inject consistency to the HD cleaners and LD cleaners will be 3,5 and 1,5% respectively.