Paper Industry Presentation

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PULP AND PAPER INDUSTRY An Overview Presented by: Ajay Yadav - 111501 Mukesh Kumar - 111522

Agenda:

Agenda Introduction Generalized process flow Pulping and its types Wood based pulping Agro-residue based pulping Recycled based pulping Paper manufacturing Environmental impacts of paper industry Conclusion References

INTRODUCTION:

INTRODUCTION The pulp and paper industry is one of India's core sector industries. The socio-economic importance of paper has its own value to the country's development as it is directly related to the industrial and economic growth of the country. Although paper has many uses, its most important contribution to modern civilization is its use as a medium to record knowledge.

Generalized Process of Paper making from different types of raw material:

Generalized Process of Paper making from different types of raw material

A typical process for Paper manufacture:

A typical process for Paper manufacture

Different industrial processes in pulp and paper sector:

Different industrial processes in pulp and paper sector Based on the type of raw material used, the manufacturing processes are classified into: Wood Based Pulp and Paper manufacturing Process Agro residue based Pulp and Paper manufacturing Process Secondary fiber based Pulp and Paper manufacturing Process

Various Methods of Pulping::

Various Methods of Pulping: Mechanical Method of Pulping Chemical Method of Pulping Semi Chemical Method of Pulping

Mechanical Pulping:

Mechanical Pulping Mechanical pulping uses mechanical abrasion to separate cellulose fibers which are held together by lignin.

Chemical Pulping::

Chemical Pulping: Chemical pulping achieves fiber separation by dissolving the lignin.

Types of Chemical Pulping::

Types of Chemical Pulping: There are three chemical pulping methods… Soda Chemical Pulping Kraft (or Sulfate) Chemical Pulping Sulfite Chemical Pulping

Soda Pulping::

Soda Pulping: Soda pulp is the original chemical pulp and is produced by cooking chips of deciduous woods in a solution of caustic soda under pressure.

Kraft(Sulfate) Pulping::

Kraft(Sulfate) Pulping: In the Kraft process, an aqueous solution of sodium hydroxide and sodium sulfide, known as white liquor, selectively dissolve the lignin and make it soluble in the cooking liquid.

Oxygen De- lignification Tower::

Oxygen De- lignification Tower:

Sulfite Chemical Pulping::

Sulfite Chemical Pulping: Sulfite pulping uses sulfurous acid and an alkali to produce pulps of lower physical strength and bulk, but exhibits better sheet formation properties.

Semi-Chemical Pulping::

Semi-Chemical Pulping: Semi-chemical pulps are essentially mechanical pulps that have been pre-treated with a sulfite or sodium hydroxide liquor to improve breakdown and reduce energy requirements during processing.

Step 1- Pulping::

Step 1- Pulping:

Debarker:

Debarker

Chipper :

Chipper

Digester:

Digester

Practical Digester:

Practical Digester

Step 2: Pulp Washing :

Step 2: Pulp Washing After the wood is pulped, the pulp that is created is washed to remove the dissolved lignin and chemicals. The washing process occurs at high temperatures which generates a large volume of exhaust gases containing hazardous air pollutants which are released to the atmosphere.

Batch Washer:

Batch Washer

Continuous Washer:

Continuous Washer

Step 3: Pulp Bleaching:

Step 3: Pulp Bleaching After washing, if a white product is desired, the pulp must be bleached to remove color associated with remaining residual lignin. Typically, in the bleaching process, the bleaching chemicals are injected into the pulp, and the resulting mixture is washed with water.

Unit operations in a bleaching stage:

Unit operations in a bleaching stage

Bleaching Process:

Bleaching Process

Bleaching Tower:

Bleaching Tower

Bleached and unbleached pulp::

Bleached and unbleached pulp:

Agro Based Pulp and paper manufacturing Process::

Agro Based Pulp and paper manufacturing Process:

Raw material preparation :

Raw material preparation De dusting De pithing leaf removal

Raw material Preparation section:

Raw material Preparation section

Pulping Section :

Pulping Section Pulping comprises of cooking or digestion followed by washing, bleaching and centricleaning. washing bleaching centricleaning

Cooking or Digestion:

Cooking or Digestion There are two types of digestion processes employed similar to wood pulping; Batch digestion carried out in spherical digesters Continuous digestion process carried out in a pandia type digester. The agro residue is chemically digested in a digester at 150 – 160 °C and 6 – 7atm pressure for about six hours. Charging and discharging takes 1.5 hours and 0.5 hours respectively.

Batch (Spherical) Digester:

Batch (Spherical) Digester

Continuous digester (Pandia digester ):

Continuous digester (Pandia digester )

Washing :

Washing The pulp is then pumped to the washers for washing with fresh water in the final stage and backwater in the previous stages. The wash water called black liquor, which has total solids content of around 7-10% due to residual alkali and lignin. This liquor is mostly discharged to drains as chemical recovery has so far been economically unviable.

Wheat straw washing section:

Wheat straw washing section

Screening :

Screening The washed pulp contains sand and uncooked agro residue as impurities. The impurities are removed through screening and centricleaning. After screening, which is carried out at 1% consistency, the pulp is thickened to about 4% for next operation, namely bleaching.

Bleaching :

Bleaching The bleaching in small mills is carried out using calcium hypochlorite (hypo), which is added in two stages in order to provide sufficient retention time for hypo and to minimize the fiber degradation. After bleaching, the pulp is washed, partly with fresh water and partly with white water (paper machine back water).

Conventional vacuum drum washer after bleaching:

Conventional vacuum drum washer after bleaching

Stock Preparation :

Stock Preparation The bleached pulp is mixed with the long fiber pulp, comprising mainly rags and waste paper pulp. The chemicals added to the blending chest are rosin, alum, talc, dye (optional), optical whitener and high gum. The chemicals (additives, fillers etc) solutions are prepared and added manually in every batch.

Waste paper pulping:

Waste paper pulping Recycled paper (Waste), newsprint and magazine is charged in Hydraulic Pulper with adding water and it is being processed till waste paper is converted into slurry form with high consistency pulp. Then it is transferred to machine chest where addition of dye, chemical takes place. This pulp then is fed to the machine chest

Hydro pulper used for pulping wastepaper/recycled material:

Hydro pulper used for pulping wastepaper/recycled material

Hydropulpers:

Hydropulpers

Deinking process :

Deinking process Deinking is a recycling technique that can produce high quality recycled pulp from recovered papers. Flotation Deinking which makes ink particles hydrophobic by means of a collector in a flotation cell. The air bubbles generated at the bottom of the cell carry the ink particles to the surface where they are confined in foam which is removed.

Conventional Chemical washer:

Conventional Chemical washer

Paper machine overview (Fourdrinier-type paper machine):

Paper machine overview ( Fourdrinier-type paper machine )

Paper Machine:

Paper Machine The blended pulp is again centricleaned to remove impurities and finally fed to the paper machine through a head box. From the dewatering and paper making angle, the machine has three principal stages: • The gravitational and vacuum dewatering stage (wire part) • The mechanical dewatering stage (press rolls part) • The thermal drying stage (indirect steam dryers)

Continued….:

Continued…. On the wire part of the paper machine, the dewatering of pulp takes place by gravity and vacuum. The water from the wire mesh is collected in a fan pump pit and is continuously recycled to dilute the pulp fed into the paper machine centricleaner. After the wire part, the edge cutting operation is carried out to obtain paper of a definite width. The edge cuts of the pulp web falls in the couch pit and are recycled to the machine chest.

Continued….:

Continued…. Towards the end of the wire part of the machine, the consistency of pulp rises to about 20 per cent. Further dewatering is carried out by press rolls to raise the consistency to about 55%. The paper is finally dried through an indirect steam dryer to about 94% solids and is collected in rolls as the final product.

Paper machine section:

Paper machine section

ENVIRONMENT IMPACT OF PULP AND PAPER MANUFACTURING PROCESS :

ENVIRONMENT IMPACT OF PULP AND PAPER MANUFACTURING PROCESS Pulping often releases a range of pollutants, including organic products which cause eutrophication in water, aluminum salts and sometimes also generation of sulphur dioxide. When bleaching is carried out with chlorine or hypochlorite, it may generate dioxin. These pollutants have direct impacts on freshwater and marine ecosystems near pulp mills.

Air Emissions:

Air Emissions Air pollution mainly occurs from digesters blow tanks, steam boilers, chemical recovery boilers.

Solid waste:

Solid waste Solid waste is generated in the form of sludge, ash, wood waste, screening, centricleaner rejects, sand and grit. The major concerns with these wastes is their disposal.

Conclusion:

Conclusion

References:

References [1] N. DeKing, Ed., Pulp & Paper Global Fact & Price Book 2003–2004 . Boston: Paperloop, Inc., 2004. [2] G.A. Smook, Handbook for Pulp and Paper Technologists , 2nd ed. Vancouver, BC, Canada: Angus Wilde, 1992. [3] F. Kayihan, “A review of modeling and control in pulp and paper industries,” in Proc. 5th Int. Conf. Chemical Process Control (CPC V): AIChE Symp. Ser. , 1997, pp. 117–132. [4] J. Minor, “Pulp,” in Kirk-Othmer Encyclopedia of Chemical Technology , 3rd ed. , M. Grayson, Ed. New York: Wiley, 1982, vol. 19, pp. 379–419. External Links http://en.wikipedia.org/wiki/Pulp_and_paper_industry Confederation of European Paper Industries American Forest & Paper Association (AF&PA) Forest Products Association of Canada (FPAC)

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