Paper Technology Journal 19 - Voith

3
12
The new DIP 2
DIP 2 can supply both PM 4 and also the
existing PM 1. Although one chemical
pulp line exists, the joint objective, however,
is to produce LWC paper from
100% recovered paper on PM 4 with a
quality equivalent to that of customary
virgin stock-based LWC papers.
The DIP went into trial operation (Fig. 4)
at the end of June 2004 – a few weeks
before start-up of the new PM 4. For the
start of PM 4, high-quality stock was,
therefore, already available.
Engineering and scope of supply
In DIP 2, with a capacity of up to 850 t/
24 h o.d. finished stock, intermediate
chests have been largely dispensed with.
Intelligent placing of the individual components
has considerably reduced the
necessary space. Short piping distances
in conjunction with the use of frequencycontrolled
pumps lead to low specific energy
costs. The overall engineering was
based on a 3D model (Fig. 3).
5
19/05
TwinDrum pulping
HC cleaning (HIPro)
Rejects
handling
Hole screening 1.6/2.0 dia.
EcoMizer Cleaning
Loop I Loop II
PM Loop
IC screening // 0.20
Flotation I
LC screening // 0.15
Disc filter I
Screw press I
Disperger I
Bleaching I, oxidative
Sludge
handling
Conus
Trenner
Chem.
pulp
DAF 2
DAF 3 DAF 1 Disc filter
Pre-thickening
The individual machines have been combined
in just a few group starts. An overall
production control system ensures a
high degree of operator convenience.
Close cooperation between process engineering
and automation resulted in a very
short planning time. An important module
– the system for dewiring and intermediate
storage of the incoming recovered
paper and feeding it to the DIP –
was designed in close partnership with
LEIPA. The overall engineering and supply
of the additive preparation system required
for the preparation process was
also Voith’s responsibility. The rejects
are handled with a concept developed
and implemented completely by Voith’s
partner Meri.
A chemical pulp line for slushing and refining
of up to 150 t/24 h was also supplied.
The technological concept
Based on the results of extensive trials, a
2-loop deinking system with the following
key components was designed jointly
with LEIPA (Fig. 5):
Flotation II
Disc filter II
Screw press II
Disperger II
Bleaching II, reductive
Storage tower
Conus
Trenner
Refining
Approach flow
Paper machine
Fresh water
PM shower water
4
● The innovative TwinDrum slushing
concept combines gentle breaking
down of the paper into the individual
fibres with reduced additive requirement
● The revolutionary EcoMizer cleaner
concept ahead of Flotation I
● One of the largest EcoCell flotation
systems (throughput up to 1000 t/24 h
in Loop I)
● Thickening using Thune Bagless disc
filters and a further development in
Thune screw presses
● 2 dispersion systems with a new
disperger concept and SpeedHeater for
efficient stock heating and additive
blending
● The proven C-bar screen baskets
in IC and LC slotted screening.
Brief outline of the process
After the bales of recovered paper have
been dewired and mixed with loose paper,
the mixture is stored in bays. A
wheel loader loads the furnish from the
storage bays onto a conveyor belt which
feeds the TwinDrum. Here the recovered
paper is gently broken down into individual
fibres at a consistency between 25-
28%. This high stock consistency as well
as good mixing of the stock thanks to the
integrated displacer achieves excellent
printing ink detachment.
Once coarse contaminants have been
removed from the stock using 2-stage
heavy particle separation and 2-stage
hole screening systems, it is then stored
in the dump chest. The subsequent stock
cleaning at a consistency of 2 % using
EcoMizer cleaners provides efficient dirt
particle removal and protects the following
IC slotted screening system. One of