Tuesday, June 09, 2015 PRESS FELT CLEANING AND CONDITIONING.

Tuesday, April 18, 2023 www.venpap.com 1

PRESS FELT CLEANING AND CONDITIONING

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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.


PROBLEM: Water shower penetrates the felt from a single side, result: low air/water flow and void volume

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 in the dryer section.

Existing Uhle box

Existing Water Shower; Water in and out from same side

VenPap Blow Box : Hot air and steam mixture through the opposite side – both sides of the felt are open

Vacuum level in Uhle and characteristics of the mixture for Blow Box is simply adjusted by the steam valve

Optional ON or OFF

Cross-section of press fabric after water shower conditioning – only one side is open

Blow VenPap Box is located over the uhle box and blows a mixture of hot air and steam from the steam jet ejector through the unaffected side of felt. It supports the opening of felt which instantly improves the flow of water in the pressing process. The further rise in temperature increases void volume along with the compressibility of the felt. Steam Jet Ejector works simultaneously as a vacuum pump and complements enhanced air flow through the felt. The PM Operator has the ability to precisely control the felts conditions for each press at all time. Keeping optimal conditions of the each felt brings better dewatering in the pressing process.

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VACUUM STEAM EJECTOR

Existing Vacuum Pump

Control Room

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 preheating.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.

Vcuum


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.

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.

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Exemplary balance of steam: Use for VenPap System = - 500 lb /h

( one felt conditioning) Saving in the dryer = + 5500 lb/h

Net Saving = +5000 lb/h

VenPap Install

VenPap


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 www.venpap.com/pilot.html


Change of the steam consumption for PM 220,000 t/year

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 adjustment

STEP 4 – Measurements of the paper dryness, overview of results

Tuesday, June 09, 2015 PRESS FELT CLEANING AND CONDITIONING.

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Transcript of Tuesday, June 09, 2015 PRESS FELT CLEANING AND CONDITIONING.