PULPING OF WHEAT STRAW USING SULFITE PROCESS: AN EXPERIMENTAL STUDY

1
PULPING OF WHEAT STRAW USING SULFITE PROCESS AN
EXPERIMENTAL STUDY

• By
• MAH-E-KAMIL
• B.Sc Chemical Engineer
• (STUDENT OF I.E.C.T)

2
Motivation to study

• Increasing demand of paper products
• Decreasing Forests
• Need of alternatives
• Wheat straw is agricultural waste
• It can be used for making pulp

3
Experimental set up
4
COOKING LIQUOR COMPOSITION
5
TESTING STANDARDS
6
DIFFERENT PULPING PROCESSES

• Sulphite process
• Soda process
• Mechanical process

7
SULPHITE PROCESS

• Almost all type of wood can be used
• Cooking conditions
• Temperature 340-350 o F
• Pressure 100-125 PSI
• Cooking time 2-4 hour
• Chemical s are expensive not recovered
• Pulp is corrosive in nature
• Difficult to bleach ,brown in color.
• Bag ,wrapping papers, cartons corrugated
  boards.

8
SODA PROCESS

• Used for short fiber wood
• Cooking conditions
• Temperature 330-340 o F
• Pressure 90-105 PSI
• Cooking time 6-8 hour
• Chemical can be recovered
• Pulp is corrosive in nature
• Bleaching is easy
• Printing papers and tissue

9
MECHANICAL PROCESS

• Used for soft wood
• No chemicals required
• Low energy requirements
• Cheap and low grad paper
• Pulp is improved by adding some chemical pulp

10
RESULTS AND DISCUSSION

• Yield
• Ash
• SR
• Kappa No.
• Consistency

11
RESULTS AND DISCUSSION

• Recovery of pulp from wheat straw
• A recovery value of 45 means that for every 100
  oven-dry Kg of wood processed, 45 oven-dry Kg of
  pulp is produced.
• Crude yield
• Screen yield

12
RESULTS AND DISCUSSION
13
RESULTS AND DISCUSSION
14
RESULTS AND DISCUSSION

• The residue left after complete combustion of
  pulp at high temperature (525 o C)

15
RESULTS AND DISCUSSION
Ash content decreases with increase in the alkali
ratio.
16
RESULTS AND DISCUSSION

• Schopper-Riegler number (SR)
• SR number is a relative value for the filtration
  property of pulp based on the reduction of
  filtration rate due to the formation of a fiber
  pad on the wire of the apparatus.
• Normally SR is the same for a material (e.g.
  wheat straw ,wood ,cotton ).

17
RESULTS AND DISCUSSION
18
RESULTS AND DISCUSSION

• The Kappa number is an indication of the lignin
  content or bleachability of wood pulp.
• It estimates the amount of chemicals required
  during bleaching of pulp to obtain a pulp with a
  given degree of whiteness.
• The number is in the range of 1-100 (10-70 for
  most types of pulp).
• The work of Lu Yanna and Zhang Yunzhan to study
  effect of alkali ratio also supports these
  results .

19
RESULTS AND DISCUSSION
20
RESULTS AND DISCUSSION

• It is also used for measuring the yield.
• It is common term used in the industry.
• The consistency is maximum at 10.5.
• High value is due to good cooking.
• Decrease in value is due to higher attack of
  alkali, NaOH, on the fibers of pulp.

21
RESULTS AND DISCUSSION
22
CONCLUSION

• The best pulp is produced at 10.5 NaOH and 3.5
  Na2SO3 with the following characteristics.

23
Acknowledgements

• The cooperation of Packages Lahore is
  acknowledged.

24
THANKS FOR YOUR LISTENING