Paper machine

A paper machine is the essential Technologie of the paper industry since it is generally it which produces the Papier, in the form of very bulky reels, starting from the Pulp paper.

It is composed of various parts:

* circuits of head of machine
* formation of the sheet
* the pressing of the sheet
* the drying of the sheet
* put in format of paper.

According to the type of manufactured paper, it can exist different stages or in more like the bed or satining of the paper which intervenes then after drying.

Circuits of head of machine

One gives the name of circuits of head of machine to the circuits connecting the trituration of the paper pulp to the Caisse of head of the paper machine.

The trituration of the paste includes/understands:

  • the disintegration of the balls of paste in the pulpor
  • the refining of the paste
  • the mixture, according to the composition necessary for a given paper.

All the trituration of the paste is carried out with dry matter concentrations ranging between 3 and 6%, this for economic and practical considerations:

  • reduction of volumes necessary for the transport and the storage of the paste
  • savings in energy S.

One remains however limited for problems of transport (use of the centrifugal Pompe S) to concentrations which can that very seldom to exceed 6%.

In case of head or in the tank of a round Form, for considerations of deflocculation and good formation of sheet (to épair and characteristic physiques of paper), one may find it beneficial to work more diluted possible, taking into account the capacity of the circuits and draining available on machine.

The circuits of head of machine will thus have several functions:

  1. régler the grammage (the weight with the m ² of paper) :

  2. : For a speed machine given and a constant concentration of paste in the vat machine, the grammage of paper will be fixed by the flow of paste (coming from the vat machine), which is regulated either by a valve (valve of weight or grammage) or by a positive-displacement pump at variable speed.
  3. réguler the dilution:
  4. : I.e. concentration in case of head. One uses most of the white water under fabric to dilute the paste coming from the vat of head of machine. The white paste and water are sent to the aspiration of the primary pump or pump of dilution which ensures the mixture and transport towards the case of head.
  5. réaliser purification fine:
  6. : This purification is more effective on a diluted paste (between 5 and 10 g/l).
  7. : * Purification of the heavy impurities in Hydrocyclone S. This purification very effective requires an important energy expenditure (important flow and high pressure loss ranging between 1,5 and 2,5 bars).
  8. : * Purification of the large impurities (heavy or light) in sieve purifiers: hole baskets or slit baskets. In this case, one eliminates from the “screws”, the nettings, and in certain cases of the plastiques.
    Perte of load in these apparatuses: 0,1 to 0,5 bars according to the percentage of opening, flow, concentration of the paste and the state of filling of the basket.
  9. affinage of the pâte:
  10. : For certain manufacture, one still finds a post refining head of machine allowing if necessary to regulate very quickly to épair it (better formation) and especially the porosity or Perméabilité of paper.
  11. : Certain additives used for the improvement of the product (agents of joining, dyes, agents resisting at the wet state,…) or for the improvement of process (agents of retention, etc) are introduced more and more systematically on the level of the circuits of head.
  12. : The Charges are generally introduced on this level into the circuits of paper machine.

Random links:Lao Zi | Paradoja de Olbers | Sphere of Hill | Pierre de Boissat | Leopoldina | Venray | Hispania_Baetica