press felt cleaning and conditioning

Sunday, April 12, 2015
What is the Importance of Press NIPs?
Mechanical Dewatering is 10 Times Cheaper than Thermal Drying
Without a specific vacuum system designed to remove all of the shower water
and appropriate felt conditioning, definite press inefficiencies can occur.
Water shower penetrates the felt from a single side, result: low air/water flow and void volume
Cross-section of press fabric after water shower conditioning – only one side is open
Blow VenPap Box is located over
VENPAP SOLUTION: Each felt is properly open and prepared individually for a specific
paper sheet and press, result: up to 12% savings in the steam consumption the uhle box and blows a mixture of
hot air and steam from the steam jet
in the dryer section.
ejector through the unaffected side
of felt. It supports the opening of felt
which instantly improves the flow of
in the pressing process.
VenPap Blow Box :
Hot air and steam mixture through
The further rise in temperature
the opposite side –
increases void volume along with the
both sides of the felt are open
compressibility of the felt.
Vacuum level in Uhle and
characteristics of the mixture
Steam Jet Ejector works simultaneously
for Blow Box is simply adjusted
as a vacuum pump and complements
Existing Water Shower;
by the steam valve
Water in and out from same side
enhanced air flow through the felt.
The PM Operator has the ability to
Uhle box
precisely control the felts conditions
for each press at all time.
Control Room
Keeping optimal conditions of
the each felt brings better dewatering
in the pressing process.
Optional ON or OFF
Sunday, April 12, 2015
The VenPap phenomenon is
illustrated in this animation.
A Venpap Blow Box blowing a
mixture of hot air and steam is
fixed above the vacuum box.
Here, we subject felt to extreme
conditioning along with its
At the same time better
permeability is accomplished
and felt impurities are loosened.
From there on, past the VenPap
zone, a washed, dewatered and
well prepared to absorb water
felt runs to the press process.
Sunday, April 12, 2015
Animation beside illustrates a
running Blow Box within the
VenPap System. Air-steam
mixture blown through the
vacuum slot automatically
penetrates the inside structure
of felt. Blow Box preheats felt
while thoroughly conditioning it.
The diagram illustrates a typical
steam box. A stream of pure steam
flows through the slots that can be
seen in the chart. The steam box
operates just above the paper
sheet and treats paper with hot
steam in the widest possible range.
The device’s main function is to
pre-heat paper.
A Steam box virtually does not
impact the felt and does not affect
its conditioning.
Exemplary balance of steam: Use for VenPap System =
( one felt conditioning)
Saving in the dryer
Net Saving
Sunday, April 12, 2015
- 500 lb /h
= + 5500 lb/h
= +5000 lb/h
A major problem for contemporary, high-speed paper machines is the variable condition of the felt. After several days
of work felts are characterized by varying permeability profile. Scanning felts in the cross direction to its movement
shows in which sections the felts are inadequately prepared for the pressing process.
The above diagram shows the control window for Venpap Blow Box operation. The PM’s operator sees the
graph profile of water permeability of the felt. To regulate and improve the conditioning of weaker sections
move Blow-Box sliders controllers under the graph. More at
Sunday, April 12, 2015
Change of the steam consumption for PM 220,000 t/year
Sunday, April 12, 2015
Sunday, April 12, 2015
STEP 1 – Check parameters of the felts:
moisture, permeability, temperature
STEP 2 - VenPap Project for a specific Press
STEP 3 - Supply of equipment, running and
STEP 4 – Measurements of the paper
dryness, overview of results
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