Project Title Pilot scale studies on efficient depithing of bagasse- … · Availability of baggase • Major sugarcane growing states are, Uttar Pradesh, Maharashtra, Tamilnadu and

Project Title Pilot scale studies on efficient depithing of

bagasse- a process developed by CPPRI

Project Executed by Central Pulp & Paper Research Institute

(CPPRI), Saharanpur- 247001 (Uttar Pradesh)

Presented by

Dr. A. K. Dixit Sc. E-II & Incharge

Chemical Recovery Division

CENTRAL PULP AND PAPER RESEARCH INSTITUTE, SAHARANPUR (U.P)(Dept. of Industrial Policy & Promotion, Ministry of Commerce & Industry, Govt. of India)

Project Team

Project Advisor Dr. B. P. Thapliyal

Principal Investigator Dr. A. K. Dixit

Team Member Sh. Kumar Anupam

Sh. Avtar Singh Negi

CENTRAL PULP AND PAPER RESEARCH INSTITUTE, SAHARANPUR

To develop, design and demonstration of pilot scale

depithing equipment for efficient depithing of

bagasse to provide good quality fibre for paper

making and to provide the pith as a source of fuel to

the sugar mills.

Objective


Quantified Deliverables of the Project

• To develop, design & demonstrate efficient depithing process

developed by CPPRI on pilot scale with improved depithing efficiency

of more than 80% as against 50-55% in conventional processes.

• Reduction in cooking chemicals.

• Improved pulp properties in respect of strength and optical properties.

• Improved quality of black liquor leading to enhanced thermal

efficiency of chemical recovery boiler.

• Diversion of more useful bagasse fiber to paper industry from sugar

mill.


Paper from Bagasse

• Bagasse is commonly used as a substitute for wood in many tropical

and subtropical countries for the production of pulp, paper and board,

such as India, China, Colombia, Iran, Thailand and Argentina.

• It produces pulp with physical properties that are well suited for

generic printing and writing papers as well as tissue products but it is

also widely used for boxes and newspaper production.


Availability of baggase

• Major sugarcane growing states are, Uttar Pradesh, Maharashtra,

Tamilnadu and Karnataka.

• Normally 0.30 ton of bagasse (30%) is obtained per ton of cane

crushed in a sugar mill.

• About 50 million tons of bagasse is generated annually in Indian

sugar mills.

• Out of total sugar cane produced in the country

- Only 45% is received by sugar mills

- 45-50% cane is crushed in unorganized sector.

- 8- 10% is utilized as seed for future crop.


Composition of Bagasse

Bagasse is composed of three principal components namely:

• Rind fibers,

• Fibro vascular bundles

• Ground tissue (parenchyma tissue) or pith.

Whole

Bagasse

6%

32%

62%

Useful Fibre

Pith

Dissolved Matter


Pith in Bagasse

• Major impediment in utilization of bagasse as an alternative to

wood in papermaking is the inherent carryover of pith to the tune

of 30-35% along with fibre

• Depithing is required prior to pulping of bagasse

• 60% removal of pith is possible with presently employed depithing

methods in industry. Residual pith in the depithed bagasse is above

15%.


Pith in Bagasse and its Depithing Processes

• Pith is composed mainly of parenchyma cells.

• Pith cannot be converted in to a satisfactory pulp despite its

resemblance to fiber in chemical composition, because of its small

dimensions, non-fibrous physical nature and close association with

dust.

• Efficient depithing of bagasse is essential for good quality

papermaking

• Presently Following depithing Processes are being employed by Paper

mills.

Dry Depithing

Moist Depithing

Wet Depithing


Pith in Bagasse and its Depithing Processes

COMPOSITION OF DRY/MOIST DEPITHED BAGASSE

COMPOSITION OF WET DEPITHED BAGASSE

COMPOSITION OF CPPRI DEPITHED BAGASSE


Efficient Depithing Process Developed by CPPRI

• The method involves mechanical treatment of bagasse by passing it

between two disks typically used for short milling operations.

• The treated mass so obtained is subjected to a specially designed

sieving mechanism whereby the useful fibrous portion is

separated from the pith portion in a continuous operation.


Activities carried out

• CPPRI had installed a depithing system based on its R&D work.

• The system had bottlenecks on:

Frequent jamming of the feeding system

Low capacity of existing screen part

• Looking into the above problems, fabrication of a new feeding system and

screen part was done using indigenous design developed by CPPRI.

• The main goal was to increase the capacity of the existing pilot plant by

fabricating a new whole bagasse feeding system with no jamming

problem.

• Hence, to design and fabricate a new large capacity screen part to

synchronize the increased capacity of feeding and processing system with

the screen part.


Old Feeding System


New Modified Feeding System


Photograph of new feeding system


New versus old feeding system

• New feeding system is equipped with a motor which has increased the

throw put capacity of the depithing plant.

• The bagasse processing capacity of the depithing plant has increased

from previous 3 – 4 tons to present 5 tons.


Schematic of Depithing Plant Screen


Old versus New Screen Part Specifications

Parameter Old Screen New Screen

Length of Screen 2.5 m 3.0 m

Mesh Size 01 (Fixed) 03 (Varying)

Polypropylene Brushes Fixed Replaceable

Screen Diameter 365 mm 500 mm

Dia of Shaft 40 mm 40 mm

Material of Construction Mild Steel Mild Steel


New Fabricated Screen


Various Parts of New Fabricated Screen


Complete Depithing Pilot Plant


Bagasse and depithed bagasse samples


Benefits of the process

Pith to Fibre ratio in Bagasse after Depithing


Impact of depithing on pulp properties


Conclusion

• An efficient depithing process has been developed and upscaled to pilot level

which can depith bagasse with 85% depithing efficiency.

• Depithed bagasse has around 6-7%% pith.

• Studies have shown that feeding rate has improved with no jamming problem

withnew feeding system which is perfectly synchronous with new screen part.

• The efficiently depithed bagasse was processed for production of high quality

pulp. Quality of pulp and black liquor were improved.

• Viscosity of black liquor reduces.

• The operation of depithing plant has been demonstrated before various sugar

and paper mills such as Bajaj Hindusthan Sugar Ltd., Yash Paper Mill, Century

Pulp and Paper, and Tamilnadu News Prints & Paper Ltd.

• This pilot plant is available at CPPRI. The mills can come for trial and adoption

of the technology.



Project Title Pilot scale studies on efficient depithing of bagasse- … · Availability of baggase • Major sugarcane growing states are, Uttar Pradesh, Maharashtra, Tamilnadu and

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