4400mm Valmet Kraft MF Paper Machine 600m/min (2147)
Paper Weight: 40 – 140 GSM
Machine speed: 400-600 m/min
Trimmed width: 4 400 mm
Capacity: 40 000 t/y
This machine was designed for packaging papers, from sulphate pulp on the first fabrication cycle (virgin fiber) and it was stopped in 2010 but it is conserved really well because during 2012 was prepared to start again.
Since commissioning (1966) and so far this paper machine has been upgraded in several stages, and were implemented new paper types required by the evolution of markets.
From 2005, as a result of modifications in the technological plants was obtained diversification of the paper sorts. So, it was obtained bleached and natural waterproof paper (using an agent which gives this character to paper) and paper suitable for printing – writing with filler material (calcium carbonate). This paper was noncalendered having only MF smoothness (machine finished).
Types of produced and marketed paper
Bleached kraft paper for ennoblement , bags or packaging
Unbleached kraft paper for ennoblement, bags or packaging
Paper for corrugated board
Unbleached waterproof paper
Bleached waterproof paper
Bleached sulphate paper suitable for printing –writing
The raw material used to paper fabrication
Softwood sulphate pulp , in the percent of 100 – 60 %
Hardwood sulphate pulp , in the percent of 0 – 40 %
Along with fibrous raw material are used several chemicals, according to the fabrication receipts
The fabrication receipts of papers produced on this machine enclose
Softwood sulphate pulp , bleached or unbleached
Hardwood sulphate pulp , bleached or unbleached
The percent of each compound depends of the fabrication receipts.
The technological flow is divided in the following main sections:
The material consisting of cellulose pulp (long and short fiber) is ground (refined) in Conflo refiners type JC, treated with additives and screened, before be launched on the paper machine.
Launching of material on the paper machine
The hydraulic headbox type SymFlo was installed during 2005 to support the production increasing and to improve the quality of papers. This headbox is controlled by ABB system that provides cross-profiling of the weight. The main role of headbox is to ensure the uniformity of weights in the transversal direction and a good profile of the fiber orientation, the essential characteristics in quality paper. The consistency of the material to inlet in the headbox is 0.25 – 0.7% , depending of the weight of paper produced.
Material dewatering and sheet forming on the wire table
On the wire table takes place dewatering of paper up to a consistency of 16- 20% depending on the sort of paper. This section was modernized in 2007 with the company IBS Austria. The new concept of this section and the automatic vacuum control provides the improved sheet forming and better dewatering, confirmed by paper dryness after wire table section. The blades (slides) and the caps of dewatering units are made by ceramic material resistant to wear and friction.
Press section consist of three presses: two suction presses and one
Fabric press, and also the pick-up roll.
This section has been modernized in the period of 2005-2007 by modifying the rolls shell concept and installation of performing equipment of maintenance and conditioning of rolls and felts. These changes are intended to provide a better dewatering. The press section is the final part of the wet zone where is finalizing the physic-mechanical properties of paper. Each additional dryness degree achieved in the press zone leads the steam consumption decreasing with about 4 %.
Consistency of paper sheet in this section is the following:
– Press I inlet =16 – 20%
– Press II inlet = 20 – 25%;
– Press III inlet = 25 – 30 %;
– Dry section inlet = 30 – 35 %.
Diameter 1500 mm
Working pressure 4 bar
Dry section consist of five groups of drying cylinders , each group being equipped with drying sieves, having the role in improving the water elimination from the sheet and carrying paper.
Dryer cylinders are supplied with steam of a given quality (primary, secondary or tertiary) depending on their position in the drying zone.
Dry section is supported by auxiliary ventilation and steam/condensate systems which provide the thermal balance of drying. The quality of paper, steam consumption, power energy consumption and microclimate in the production room depend on the proper functioning of these systems.
Ventilation and steam condensate systems were modernized during the period of 2005-2007 by Langbein – Germany.
The ventilation system has blowing boxes type pocket, which ensure effective ventilation near paper sheet and in the steam-condensate system was improved the condense evacuation and thermal exchange of dryer cylinders.
Consist of 2 rolls and ensure the paper smoothness. It was changed in 2005 with one swimming roll but this presented difficulties in the operation from the beginning and have not reached the proper parameters.
Its role is to provide a dense and uniform winding of paper sheet. It was replaced in 2007 with automatic one supplied by Freiria- Italy, which automatically provides the changing of drums and paste of paper on the new drum. The weight of new drums is over 20 to and this provides the constant production and quality of paper. In addition, this operation mode provides the protection for operating personnel.
Driving system of paper machine
This system consist of AC drives type ACV-70, AC motors totally closed, with supplementary fun on each motor, and local operating stations with software applications. The actual driving system allows greater operating flexibility an increasing the machine capacity to 60.000 to/year.
It was replaced in 2005 with ABB system. It has the role to provide the control and the regulation of operating parameters.