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Retention agents

Retention agents use systems


The family of retention agents is very wide. A paper machine retention system is a very important part of the PM overall chemicalisation. A proper attention should be paid to its selection so that required results are achieved.

In fact the retention systems have one, two, sometimes even three ingredients. PAPCEL offers solutions for all three mentioned systems. In practice either a sole polymere from the polyacrylamide (PAM) group is used, or the same in a two-ingredient system combined with bentonite, cationic starch or silica. The retention aid systems are able to work both with liquid and with powder PAM based commercial products. In both cases the needful stations are designed with regards to a maximum operation reliability. The parameters on both the equipment dosing side and above all on the powder dissolving side should be always constant and without fluctuations possibly causing consequent PM operation troubles. Above all the preparation of PAM solutions is designed fully automatedly. The powder products are exactly dosed by precise screw batchers with a continuous control by means of frequency converters, diluting water is measured with induction flowmeters. The other variables and/or parameters like a mixing time, dosing, a proportional dilution to a work concentration, recording levels in work and dilution tanks, a quantity of product in a hopper and others are controlled either by the built-in high-tech control system (CS) or the station is delivered without a CS and it is controlled from the PM existing DCS. In such case an integral part of a PAPCEL station delivery is a logics needed to compile SW for the existing DCS.

A bentonite station design presumes purchasing powder packed in Big-Bags. Thus the bentonit station is usually composed of a Big-Bag tower with a lifting device (or an existing crane can be utilised), a precise screw batcher, a diluting tank, a storage tank and a needful dosing screw (Mohno) pumps with a proportional dilution to work concentrations. For diluting, either pure filtrate or stock drained from piping before the PM headbox is used. This solution is relevant for high performance PMs and generally wherever we need to significantly reduce a water consumption.

A control of bentonite preparation stations is designed the same way like the one of polymere preparation stations. Thus the stations can be delivered with control systems or the PM existing DCS can be utilised.

Parameters:
  • PAM (commercial product) dose amount: 100 - 500 g/t
  • Outlet dose according to PM capacity (usually for PM 1 to 25 t/h)
  • Concentration of reserve solution: 0.3 %
  • Concentration of working solution: 0.3 %
  • Concentration before dosing: 0.3 %
Main parts of the equipment for retention polymers preparation: 
  • Hopper for powdered product
  • Precise screw doser of powdered product
  • Dosing pump for commercial product in liquid form into storage tank
  • Storage tank with agitator and dilution water supply
  • Re-pumping station of reserve solution into working tank
  • Working tank for diluted product with agitator
  • Dosing pump for diluted product
  • On-line dilution circuit with output distributor according to number of dosing points
  • M&R instrumentation
  • Electric switchboard with control system
  • Mounting frame of equipment