Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching...

65
Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur, UP

Transcript of Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching...

Page 1: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Modern & Eco-friendly

Pulping & Bleaching

Techniques

By

Dr. Vimlesh Bist

Central Pulp & Paper Research Institute

Saharanpur, UP

Page 2: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

CONTENT

� Pulping and bleaching scenario

� Modern Pulping Technologies

� Modern Bleaching Technologies

Page 3: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

• Environment Norms* Increased environmental concern & awareness

* Environmental campaign on industrial usee of Chlorine and

release of Dioxin in Pulp Bleaching.

* Enforcement of stringent environmental regulations on discharge

of Organochlorine compounds which resulted in

- Wider use of extended delignification

- Oxygen Delignification

- Eop, Substitution of Chlorine with Chlorine

Dioxide

- Secondary treatment of effluents

• Pulp Quality* Paper Machine runnability

* Strength requirements of end products

• Market Force

* Customer requirement

The Need for Modern Developments

Page 4: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Limitations in Indian mills

� Variation in the capacity

� Variation in raw material

� Investment cost

Typical investment cost for 100000 TPA pulp mill

Extended delignification – 12 million USD

Oxygen delignification – 10 million USD

ClO2 generation plant – 16 million USD

Page 5: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Pulping & Bleaching Scenario (1970-2006)

1970

1975

1985

1990-2006

Conv.

CookingBleaching

O2 Delignification

Modified batch Cooking

Disp. - Super Batch/ RDH

Kappa No.30 25 20 15 10 5 0

Enzyme, ECF/TCF

Bleaching

Page 6: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Variables associated with the raw materials

•Fiber dimensions

•Chemical Composition

•Density- Bulk density/packing density

Physical size and shape of log

•Moisture content

•Porosity

•Storage conditions

Page 7: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

� Chemical composition and sulphidity

� The amount of chemical added

� Bath ratio

� Time/temperature of digester, H factor

� Chip dimensions

� Chip impregnation

� Pressure

Major variables

Page 8: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

H-FACTOR

The H-factor is a way of expressing

amount of Delignification, which takes

place during a cook. As Per definition the

H- factor is the area under a cooking

curve of relative reaction rates vs. time.

Page 9: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,
Page 10: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Developments in Pulping Technologies

�Developments in Batch cooking

�Developments in continuous cooking

Page 11: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Batch or Conventional Cooking

Until 1950’s only Batch digesters were used to produce Kraft Pulp

In late 70’s and early 80’s following developments took place

• Modified Cooking Chemistry Principles (Alkali Profiling

and low content of dissolved matter)

• Extended Cooking

• Energy Efficient Liquor Displacement Cooking

Page 12: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Batch or Conventional Cooking

1. Level out the alkali concentration- lower at

beginning, higher at end

2. High HS- concentration- specially at the start of

bulk delignification

3. Keep dissolved lignin low- especially at the end

of cooking

4. Low temperature.

Principles of Liquor Displacement Cooking / Extended Delignification

What is Liquor Displacement Cooking ?

Heat and residual chemicals remaining in Black liquor at the end of

the cooking are captured for reuse in subsequent batch cooking.

Page 13: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Conventional Batch Cooking Modified Batch Cooking

Loss of Cooking selectivity at

specific Kappa Number

Flexibility (Process & Raw

Material)

Hot Blow results in strength

degradation

Lower kappa numbers were

possible without loss in quality

The fiber undergo mechanical

stress resulting into poor pulp

strength

Respond to environmental

challenges

Terminal Displacement

- Digester contents are cooled to stop reaction after desired delignification is reached.

High pulp strength delivery and

yield

Digestor discharge by dilution and

pumping which is a gentle technique

Page 14: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

77

95

0

10

20

30

40

50

60

70

80

90

100

Strength

Delivery %

Conventional Batch Liquor Displacement Batch

Strength Delivery of Pulp from Conventional &

Displacement Batch Digestors

Page 15: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

42

44

46

48

50

52

54

10 20 30 40

Diplacement

Coventional

Yield vs Kappa Number for Conventional & Liquor

Displacement Batch Cooking of Soft wood Kraft Pulps

Page 16: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Cooking Cycle (Sunds Defibrator)

Chip

Fill

20

Chip

Steami

ng

20

Liq

Fill

15

Heating

90

Cooking

60

Degassin

g + Blow

25

Conventional Cooking

Displacement Batch Cooking

Chip

Fill

30

Warm

Liquor

Fill

30

Hot

Liquor

Fill

35

Heating

20

Cooking

45

Displacement

40

Discharge

30

Page 17: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Developments in Batch cooking

� RDH

� Super batch

� Enerbatch

� Cold Blow

Page 18: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Rapid

Displacement

Heating

(RDH)

Impregnation Temperature is 125-130oC

Addition of white Liquor in

Impregnation is necessary

Upward Flow Displacement

Super Batch Initial Impregnation with Black Liquor

at approximate 80-90o C Upward Flow

Displacement

EnerBatch Downward Flow Displacement

Clod Blow No warm Impregnation Stage

Development in Modified Batch Cooking

Page 19: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,
Page 20: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,
Page 21: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Developments in Continuous Cooking

• First Prototype Continuous Digestor started in 1938 at a mill in

Sweden with capacity of 20 t/d

• First commercial digestor with capacity 30 tons per day

commissioned in 1948 in a Swedish mill.

• In 1962 in digestor washing called high heat washing became

available

• High heat washing simplified the brown stock washing plant

• 1983 the first mill trials with modified Kraft cooking (MCC) were

performed in Finnish mill.

• MCC was developed by STFI & Royal Institute of Technology

Stockholm Sweden.

• 65% of global Kraft pulp production is manufactured by

continuous cooking.

Page 22: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Developments in Continuous cooking

� Modified Continuous

� Iso Thermal Cooking

� Black liquor impregnation

� Low Solid Cooking

Page 23: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

MCC Split or multiple WL additions for alkali profiling and counter cooking

methods to minimize lignin concentration at the end of cook.

EMC High heat wash zone is simultaneously used for cooking and washing.

ITC

Advantages

High heat wash zone is simultaneously used for cooking and washing

� Low knots & rejects

� Uniform cook with high yield

� Improved Bleachability

� Higher brightness ceiling

Low Solids

Pulping

Dissolved wood solids are removed from the system by extracting spent

liquor at multiple locations

First commercial installation in 1993.

Black Liquor

Impregnation

Advantages

Black liquor pretreatment enhances the delignification during Kraft cooking

and improves the selectivity of the cook

Extracted Black liquor is added to the impregnation vessel with a retention

time of 45 minutes.

Improved pulp properties , improved tear strength(10 % Approx) at the

same tensile strength

Development in Continuous Cooking

Page 24: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,
Page 25: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,
Page 26: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Continuous Digester for Agro based Mills

(Pandya Type)

Page 27: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Cleaner Technology-Pulping

Technology Advantages

RDH, Super batch,

Enerbatch

CC +MCC+ITC

Reduced energy requirement,

high pulp yield, Better strength

& uniformity,Lower kappa,

Lower bleaching chemical

requirement.

1995- onward

CC+MCC+ITC

BLI+MCC+ITC

Low Solid Cooking

Better Pulp properties

Low temperature uniform

cooking, better yield

Page 28: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Adv/Disadvantages of

Conventional Batch

DigestingAdvantage•Operational flexibility

•Produce diff. Grades in same digester

•Sharp kappa number change

•Tolerant to pins and fines

•Capacity increased by adding

digesters

•Less sensitive to chips quality

Disadvantage

•High energy use

•Limited capability to extended

• Delignification

Adv/ Disadvantages of

Con. DigestingAdvantage

•More constant steam demand

•More compact less space requ.

•Uniformity in pulp quality

•Extended Delignification possibility

•Better pulp strength

Disadvantages

•High capital investment

•Restriction for type and raw

material quality

Page 29: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Pulping of casuarina- bole and branch (debarked)

Page 30: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Modern Development in

Bleaching Technology

Page 31: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Symbol Chemical Symbol Chemical

C Chlorine Z Ozone

D Chlorine dioxide E Sodium Hydroxide

H Hypochlorite X Enzymes

O Oxygen Q Chelating agents

(reduce the metal ion

Conc.Mn.,Fe,Cu)

EDTA,DTPA

P Hydrogen

peroxide

A Acid

Chemicals Used in Bleaching Processes

Page 32: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Oxidant Symbol Code/form Function Advantages Disadvantages

C Cl2 gas Oxidize &

chlorinate Lignin

Effective, Economical Can cause loss of

pulp strength

O O2 Gas used with

NaoH sol.

Oxidize &

solubilize lignin

Low chemical

cost,provide chloride

free effluent for

recovery

Large amount

required,expensi

ve equipment ,

lossof pulp

strength

H Ca(OCl)2 or NaOCl Oxidize, brighten &

solubilize lignin

Easy to make and use Can cause loss of

pulp strength

D Clo2 Oxidize, brighten &

solubilize lignin

Achieve high

brightnesswithout pulp

degradation,good

particle bleaching

Expensive, must

be made on site

P Na2O2(2-5%)Sol. Oxidize, brighten

lignin

Easy to use , high yield

& low cost

Expensive , poor

particle

bleaching

Z O3 gas Oxidize, brighten &

solubilize lignin

Effective, Provide

chlorine free effluent

for recovery

Expensive , poor

particle

bleaching

E NaoH(5-10%)Sol. Hydrolyze &

solubilize lignin

Effective &

economical

Darkens pulp

Functions & Economics and Technological Implications of Bleaching Agents

Page 33: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Formula

Weight

(g/mol)

Electron

transferred

/molecule

1 kg equal

to kg act.

Cl2

C12 + 2e- ���� 2Cl-

ClO2 + 2H2O + 5e- *���� Cl- + 4OH-

NaOCI + H2O + 5e-���� NaCl + 2OH-

O2 + 2H2O + 4e- ���� 4OH-

H2O2 + 2H+ + 2e- ���� 2H2O

O3 + 3H+ + 6 e- ���� 3OH-

7 1

67.5

133

32

34

48

2

5

2

4

2

6

1

2.63

0.53

4.43

2.094.43

Reactions and oxidizing equivalents of

bleaching agents

Page 34: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Selection of right sequence

• Cost of the bleaching chemical

• Selectivity

• Ex. Chlorine being less expensive & less

selective than Chlorine Dioxide was used in

the first stage CED instead of DEC

• In the end of the sequence its use may

cause degradation of carbohydrates due to low

amount of lignin

Page 35: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Pulp type Sequence

Sulphite & Bisulphite pulp

Three stages C-E-H

Four stages C-E-H-H

C-E-H-D

C-E-D-H

C-C-E-H

C-H-E-H

H-C-E-H

C-E-D-D/H

E-C-H-D

Five stages C-E-H-D-H

C-C-E-H-H

Kraft Pulp

Three stage ,semi-bleached C-E-H

D/C-O-D

Four Stage , Partly semi-bleached C-E-H-D

C-E-H-P

C-E-H-H

C-H-E-H

C-D-E-D

O-C-E-H

O-C-E-D

O-D-E-D

O-D-O-D

Established Pulp Bleaching Sequences showing the Predominant Role of

Chlorine & Chlorine Dioxide in the Industry

Page 36: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Pulp type Sequence

Sulphite & Bisulphite pulp

Five stages C-E-H-P-D

C-E-H-D-P

C-E-H-E-H

C-E-D-E-D

C-E-D-P-D

C-E-H-E-D

C-H-D-E-D-

D-E-D-E-D

C-C/H-E-H-H

Six stages C-H-E-D-E-D

C-E-H-D-E-D

C-E-H-E-H-D

C-E-H-D-P-D

C-E-H-E-P-D

C+D-E-H-D-E-D

O-C-E-D-E-D

O-C+D-E-D-E-D

O-D-E-D-E-D

O-C-D-E-H-D

Seven Stages C-H-H-D-D-D-P

Established Pulp Bleaching Sequences showing the Predominant Role of

Chlorine & Chlorine Dioxide in the Industry

Page 37: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

� OXYGEN PRETREATMENT

� ENZYME PRETREATMENT

� OZONE BLEACHING

� ECF / TCF BLEACHING

Modern Development in

Bleaching Technology

Lignin removal before chlorination

Page 38: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Technology Advantages

Oxygen treatment-

Two stage Oxygen treatment

High kappa reduction (55%)

High brightness gain

Lower yield loss

More selective delignification

Ozone Treatment-TCF

Bleaching

Better effluent quality

Hot Chlorine Dioxide stage

Acid pre treatment

Saving of Chlorine dioxide

Better brightness development

Improves brightness stability/reduced

reduction.

Page 39: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Worldwide production capacity of Oxygen-

Delignified PulpCapacity, 1000 AD

tons/day

2 512

25

65

125

190

0

50

100

150

200

1970 1975 1980 1985 1990 1995 2000

Capacity 1000 AD Ton

Page 40: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Evolution of Oxygen-delignification Technology

Page 41: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

OXYGEN DELIGNIFICATION

Page 42: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Conditions for the Oxygen Bleaching

Pulp Consistency 3-30%

Sodium Hydroxide 2% , 1.2%

Oxygen Pressure 5 Kg/cm2

Treatment

Temperature

120oC

Treatment Time 30 min

Page 43: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Oxygen Treatment of Wheat Straw Soda Pulp

Parameters A B C

Unbleached pulp kappa 48 33.6 11.8

Unbleached pulp

brightness

23.2 28.5 33.8

Unbleached pulp Viscosity 675.2 693.2 517.6

Oxygen treated pulp

kappa

29.5 21.5 6.0

% Kappa drop 38.5 36.0 49.15

Oxygen treated pulp

Brightness

30.4 32.7 46.8

Page 44: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Oxygen Treatment of Mix Hard Wood Pulp

Parameters A B C

Unbleached pulp kappa 16 16 16

Unbleached pulp brightness 27.2 27.2 27.2

Unbleached pulp Viscosity 685.2 685.2 685.2

Oxygen treated pulp kappa 7.0 7.2 8.4

% Kappa drop 56 56 47

Oxygen treated pulp

Brightness

45 45 42

Page 45: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

CEH Bleaching of Untreated Oxygen Treated

Pulp of Bagasse

14.6

45

18

6.26.6

17

7 6.382 80

0

5

10

15

20

25

30

35

40

45

50

Kappa Number Total Cl2 NaOH Kg/t Brightness Viscosity

CEH OCEH

Page 46: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,
Page 47: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Single Stage Oxygen treatment

Page 48: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Two Stage Oxygen treatment

Page 49: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Typical Process Conditions for Two Stage ODL

Parameters First Stage Second Stage

Temp. 80-85 90-106

Pressure (top) ,bar 7-10 3-5

Retention time,min 20-40 60-80

Kappa Reduction High Low

Viscosity modest modest

Page 50: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Eo-Stage Oxygen Treatment

Page 51: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Effect of NaOH Addition

PROCESS VARIABLES IN OXYGEN

DELIGNIFICATION

Page 52: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

PROCESS VARIABLES IN OXYGEN

DELIGNIFICATION

Effect of Temperature

Page 53: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

PROCESS VARIABLES IN OXYGEN

DELIGNIFICATION

Effect of Oxygen Pressure

Page 54: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

PROCESS VARIABLES IN OXYGEN

DELIGNIFICATION

Effect of Oxygen on final pulp brightness

Page 55: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Characteristics of CEH & OCEH Bleach

Effluent (Untreated) of Bagasse

8.8

33

4.184.5

16.3

1.27

0

5

10

15

20

25

30

35

BOD mg/l CODmg/l AOX Kg/t

BOD mg/l CODmg/l

Page 56: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Characteristics of CEH & OCEH Bleach

Effluent (Untreated) of Bamboo

12.8

43.5

4.636.3

20.4

1.32

0

5

10

15

20

25

30

35

40

45

50

BOD mg/l CODmg/l AOX Kg/t

Page 57: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

OZONE BLEACHING

Page 58: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

OZONE DELIGLIFICATION

• Ozone has property of de-lignifying the cellulose, was

discovered 150 Years back by Chinese and Japanies, but

commercialized in 1960s and 1970s.

• About 25 mills are using it for bleaching of chemical pulp

• It is a very powerful oxidizing agent

• Very poorly soluble in water, 1g/l

• When generated from oxygen, only 8-12% converts into ozone

• It is less selective toward lignin than chlorine or chlorine

dioxide

• It is a strong electrophile which reacts with functional group

in residual lignin.

• Most phenolic group in lignin is oxidized by ozone.

• More selective towards lignin but its intermediate inorganic

byproducts formed by direct decomposition as HO and Hoo

are very reactive with carbohydrates.

Page 59: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Process conditions•Consistency-

The consistency is maintained to enhance the mass transfer rate

between gas and liquid phase, eith high or medium consistency is

maintained during the reaction

•pH-

Ozone delignification is more efficient at pH value near 2. The low

kappa and better viscosity is achieved at pH 2 than pH 4 or 6.

•Temperature

The best selective temperature range is 25-30oC.

•Time - 2-5 Minutes

•Additives- several additives as formic acid, acetic acid, methanol

etc. are reported, for preservation of carbohydrates combination of

dioxide with ozone is also a good substitute..

Page 60: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

OZONE AS REPLACEMENT OF CHLORINE-

• The ozone can be a substitute of chlorine, but this fact is

not realistic in case the initial kappa number is high. It

requires low kappa number entering to bleach plant (<10)

• Most commercial installation are after oxygen

delignification in DZ or ZD combinations

• Placing the Z stage towards the end of the sequences

found to increase the brightness and reduce the Ozone

requirement

• Placing Z stage between two peroxide stages reactivates

the pulps and it responsd better to the second peroxide

stage.

Page 61: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

LABORATORY BLEACHING RESULT FOR A OXYGEN

DELIGNIFIED KRAFT PULP OF KAPPA 15

(OZONE 0.5%,CY 10%, EDTA AT PH 6.3 AND H2O2 2.5% AT PH

11)

Sequence Kappa number

after bleaching

Brightness,%ISO

Z 9.9 46.7

QP 7.1 71.1

QPP 5.9 77.9

ZQP 3.6 77.5

QPZ 2.7 77.6

ZQPP 2.8 83.9

QPZP ND 89.9

Page 62: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

ECF / TCF BLEACHING

Page 63: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

ECF/TCF Bleaching

Page 64: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

DIFFERENT ECF/TCF BLEACHING SEQUENCESS

Page 65: Modern & Eco-friendly Pulping & Bleaching Techniques...Modern & Eco-friendly Pulping & Bleaching Techniques By Dr. Vimlesh Bist Central Pulp & Paper Research Institute Saharanpur,

Application Bleach sequence

Reduced chlorine (C)-P-H

(C)-P-D-H

(C)-P-H-D-H

Peroxide replacement P-D-P

P-D-H

P-H-H

P-H-D

D-P-D

P-H-D-H

P-DP-D

Oxygen bleaching O-P

O-D

O-H

O-P-D

O-D-P

O-C-P

O-H-P

O-C-P-D

O-D-P-D

Ozone bleaching Z-E-P

Z-E-Z

Z-E-Z-P

Peracaetic acid P-A-P

A-E-A-E-A

others O-Q-P

O-Q-P-P

O-Q-P-Z-P

Bleaching Sequences Designed to reduce or Eliminate the use of Chlorine Based Compounds and Chlorine