we make paper come alive !! retention-drainage-formation by: saurabh mittal ravi s joshi
TRANSCRIPT
WE MAKE PAPER COME ALIVE !!
Retention-Drainage-Formation
By: Saurabh Mittal Ravi S Joshi
WE MAKE PAPER COME ALIVE !!
• RETENTION• DRAINAGE• FORMATION• THEORY
This presentation will cover
WE MAKE PAPER COME ALIVE !!
CHARACTERISTICS THAT DEFINE A POLYMER:
• Monomers in the Polymer
• Charge of the Polymer
• Molecular Weight
• Configuration
• Natural or Synthetic
WE MAKE PAPER COME ALIVE !!
GENERAL CLASSIFICATIONS OF MOLECULAR WEIGHT
Classification
Low
Medium
High
Molecular Weight Range
< 100,000
100,000 x <1,000,000
1,000,000
WE MAKE PAPER COME ALIVE !!
RETENTION-DRAINAGE MECHANISMS
•Three steps of retention and drainage
– Coagulation
– Flocculation
– Filtration
WE MAKE PAPER COME ALIVE !!
COAGULATIONCoagulation reduces the repellant forces between fillers and fines by
development of charged patches (charge neutralization)
+
–
––
– –
–
–
–
–
–
Discrete FillersAnd Fines
Coagulant
AgglomeratedFillers And Fines
ThroughPatching
+
+
+
++
++
+ +
–
––
– –
–
–
–
–
–
+ + + + +
++++ +
WE MAKE PAPER COME ALIVE !!
Anionic Trash & Neutralization• Anionic polymeric substances able to interact with cationic polymers• Poorly washed pulps, coated broke or hydrogen peroxide bleaching are the main
sources• Highly closed systems accumulate anionic substances with time
Two Types:• Inorganic
AlumPAC
• Synthetic - low molecular weight, high-charged cationic polymersPolyaminesPolyDADMAC’s
• Generates small, compact floc structures
WE MAKE PAPER COME ALIVE !!
FLOCCULATION
• Combining or forming a bridge between particles with a polymer to produce discrete agglomerates
––
–
– –
–
––
–
–
–
––– –
–
––
–
–
–––– –
–
––
–
–
–
––– –
–
––
–
–
Attachment of HMW Polymer
Flocculation byParticle Bridging
WE MAKE PAPER COME ALIVE !!
• High level of hydrodynamic volume favors bridging - long loops and tails
• Bridging influenced strongly by molecular weight of the polymer• Bridging also influenced (to lesser extent) by the amount of polymer
charge• Generates large diffuse floc structure (macro flocs)• Shear sensitive; higher the charge, the stronger the bond
FLOCCULATION DUE TO BRIDGING
WE MAKE PAPER COME ALIVE !!
IMPACT OF SHEAR ON FLOC FORMATION
Bonds Re-formed
Charged Patches
Reduced Bridging
Redispersion
DisruptiveForce
Polymer Bridging
WE MAKE PAPER COME ALIVE !!
RETENTION/DRAINAGE
• The papermaker’s goal is to produce:– The most uniform product (formation)– At the highest speed (drainage)– At the lowest cost (retention)
• These factors are interrelated and must be balanced to meet the paper maker’s needs
WE MAKE PAPER COME ALIVE !!
•Gravity drainage•Vacuum assisted water removal•Mechanical pressure (table and press)•Drying (heat energy)
FOUR STAGES OF WATER REMOVAL
WE MAKE PAPER COME ALIVE !!
• Large flocs - high retention of fines– Stage 1: Fast gravity drainage due to large void areas between flocs.– Stage 2: Slow drainage over vacuum units due to thin spots caused by heavy
floccing. This increases the openness of the sheet and allows vacuum to be lost through the sheet.
– Stage 3: Large, high fines content flocs are dense, making it difficult to remove water by pressing and drying.
• Dispersed, unflocculated system, low retention of fines– Stage 1: Slow gravity drainage due to high fines level of system; sheet two-
sidedness.– Stage 2: Good drainage over vacuum units due to uniform sheet providing high
vacuum.– Stage 3 & 4: Good drainage in the press and dryers unless a high level of fines
causes severe two-sidedness
FACTORS AFFECTING DRAINAGE
WE MAKE PAPER COME ALIVE !!
FACTORS AFFECTING DRAINAGE
• Uniform microflocs, good fines retention– Stage 1: Small flocs provide for paths of water drainage.
Fines controlled at low equilibrium level.
– Stage 2: Uniform flocs and sheet gives good vacuum drainage.
– Stage 3: Uniform floc size and well-distributed fines give good pressing and drying.
WE MAKE PAPER COME ALIVE !!
Benefits of RDF Program
• High FPR% & FPAR%• High Chemical Retention• Lowers Back-Water Turbidity• Less Load on ETP• Better Formation at High Retention• Fast Drainage
WE MAKE PAPER COME ALIVE !!
Given: 25.00 ton/hr @ 7% reel moisture & Calculation - 23.25 ton/hr Bone-Dry Fiber
@40% Press Section Solids @42% Press Section Solids 60% water 58% water Ratio 1.5:1 Ratio 1.38:1 34.9 ton/hr water 32.1 ton/hr water
2.7 m3/hr less water to be evaporated in the dryers
Example: Volume of Water Removal
WE MAKE PAPER COME ALIVE !!
1% increase in press solids correlates to: –11-13% increase in wet-web strength
4-5% machine speed increase (directly related to production increase) on drying-limited grades
4-5% reduction in steam consumption
Drainage – Rule of Thumb
WE MAKE PAPER COME ALIVE !!
Application Technology• Flocculants
– Feedpoint Selection - Based on desired results• Post screen will achieve the most efficient and
maximum retention• Post screen will also typically provide the best gravity
drainage• Prescreen will result in less negative impact on
formation• Prescreen will result in less efficient retention but may
not reduce drainage
WE MAKE PAPER COME ALIVE !!
Application Technology• Flocculants
– Feed Scheme• Feed ring
Before or after screen
• Injection quill Often before screen
• Post dilution At least 10 to 1 More is better Fresh water if possible (can dilute at feed system) Clean white water only at feedpoint
WE MAKE PAPER COME ALIVE !!
Filler pre-treatment• Treating filler stream with additive maximizing interactions with retention program
• Non – flocculative pre-treatment
– Reduction of zeta potential – coagulant additon– Sensitizing filler particle for flocculant addition (Phenol formaldehyde resin additon)
• Flocculative pre-treatment
– Increasing filtration component of filler retention:
WE MAKE PAPER COME ALIVE !!Wet-end Process Variables Effecting RDF
• Chemistry – water and additives – already discussed• Headbox Set-up and Headbox Type • Former Set-up and Former Type• Furnish Components and Ratios• Refining• Forming Fabric• Temperature, pH, consistency, mill closure• Entrained air• Basis Weight• Distribution of fines and fillers
WE MAKE PAPER COME ALIVE !!
Case StudyMill Information: Mill is having one machine of 200 TPD along with integrated pulp of 170 TPD. They are producing pulp of 70 kappa no. Mill is producing Kraft Liner Board of 120 – 250 GSM. Mill is using bagasse as basic raw material. Mill follows Cobb 120 in place of Cobb 60 and maintaining Cobb 120 @ 50 - 60. Mill is using solid rosin along with solid non ferric alum.
WE MAKE PAPER COME ALIVE !!
Case StudyLab Trial Report: 1. Set 1:- Pulp + Alum (20 Kg) + Rosin (1.5 Kg) + Defoamer (0.8 Kg) = pH @ 4.1, Cobb 120 @ 131 & Drainage @ 340 ml/30 sec. 2. Set 2:- Pulp + Alum (20Kg) + Rosin (1.5Kg) + WSR (10Kg) + Defoamer(0.8 Kg) = pH @ 4.2, Cobb 120 @ 160 & Drainage @ 345 ml/30 sec. 3. Set 3:- Pulp + AKD (4Kg) + WSR (10Kg) + Defoamer (0.3 Kg) = pH @ 6.95, Cobb 120 @ 38 & Drainage @ 335 ml/30 sec. 4. Set 3 A:- Pulp + AKD (4 Kg) + Defoamer (0.3 Kg) = pH @ 7.1, Cobb 120 @ 63 & Drainage @ 330 ml/30 sec. 5. Set 3 B:- Pulp + WSR (10Kg) + AKD (4Kg) + DCPAM (0.15 Kg) + Defoamer (0.3Kg) = pH 7.4, Cobb 120 @ 41 & Drainage @ 398 ml/10 sec.
WE MAKE PAPER COME ALIVE !!
Case Study 6. Set 4:- Pulp + WSR (10Kg) + AKD (4 Kg) + DCPAM (0.15 Kg) + LAPAM (0.15 Kg) + Defoamer (0.3 Kg) = pH @ 7.49, Cobb 120 @ 37 & Drainage @ 400 ml/30 sec. 7. Set 5:- Pulp + WSR (10 Kg) + AKD (4 Kg) + DCPAM (0.15 Kg) + LAPAM (0.15 Kg) + Bentonite (2 Kg) + AF 270 (0.3 Kg) = pH 7.35, Cobb 120 @ 30 & Drainage @ 445 ml/30 sec. 8. Set 6:- Pulp + WSR (10 Kg) + AKD (4 Kg) + DCPAM (0.15 Kg) + Bentonite (2 Kg/T) + Defoamer (0.3 Kg/T) = pH @ 7.41, Cobb 120 @ 34 & Drainage @ 430 ml/30 sec. 9. Set 7:- Pulp + WSR (10 Kg) + AKD (4 Kg) + DCPAM (0.3 Kg) + LPAM L (0.15 Kg) + Defoamer (0.3 Kg) = pH @ 7.5, Cobb 120 @ 28 & Drainage @ 472 ml/30 sec. 10.Set 8:- Pulp + WSR (10Kg) + AKD (4 Kg) + LCCP (0.3 Kg) + LCCP (1 Kg) + Defoamer (0.3 kg) = pH @ 7.5, Cobb 120 @ 38 & Drainage @ 560 ml/30 sec.
