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					Andrew Lawes
ChE 4753
10/25/2000

                    Cold Blow vs. Modified Continuous Cooking

        Many advances have occurred in the past ten years in pulp and paper technology.
One of these has been cold blow used in batch digesters. The improvements made on
these systems has dramatically increased production output as well as decreased energy
use. There have been various plants throughout the world that have modified their
continuous cooking plants into batch digester plants and have found significant results.
This paper is going to focus on a general overview of what makes up a cold blow and
modified continuous cooking system and will focus extensively on the benefits of the
cold blow over the MCC. It will also look at how other plants have made the change
from cold blow to MCC and what improvements it has made in their production. Finally,
this paper will look at future technological advances in the cold blow system and will
address its use in other pulp and paper plants globally.

References

1. Lu, P. S. “Rebuilding of Horizontal Continuous Digester in Bositeng Hu Paper Mill”
      China Pulp and Paper 15, no. 4: 1-4 (1996). [Chin.; Engl. and Chin. sum.]

The Bositeng Hu Paper Mill in Xinjiang, China has introduced a new design for its cold-
blow horizontal tube continuous digester. The new design has increased profits, doubled
pulp production, decreased reed consumption, and improved pulp quality by using two
horizontal cold blow tubes instead of one.


2. Lin, J. P.; Qingzhou Zaozhi-chang. “Preliminary Study of Cold-Blowing, Energy-
      Saving Digestion Process” Paper and Paper Making no. 2: 23-24 (April 1993).
      [Chin.] Abstract No. 6469

3. Burkhead, J. “Strategies for Improving a Mill's Utilization of Energy”
     PaperAge 109, no. 4: 16-18 (April 1993). [Engl.] Abstract No. 2355

4. Montt M., F.; Peralta A., R.; Pozo M., J.; “Modified Cold Blow – Energy
     Optimization” Celul. Papel 7, no. 3: 15-18 (Sept. 1991). [Span.] Abstract No.
     13791

The Laja pulp mill in Laja, Chile converted its batch digesters into a cold blow process.
The digesters were found to be more energy efficient by reducing steam consumption and
reducing the temperature at the entrance of the chip exchanger, which reduced heat-
related damage previously seen in the equipment. The conversion also increased the
solids content of the black liquor, which also led to additional energy savings.
5. Pettersson, B; Sjodin, L. “Two Case Studies on the Cold Blow Technique for Batch
      Kraft Pulping” Tappi J. 70, no. 2: 72-76 (Feb. 1987). [Engl.] Abstract No. 14144

The Dynas mill and Karlsborg mill were studied on their effects of cold blow technology.
The Karlsborg mill produces market bleached kraft pulp and saw shorter heating and
blowing times in their system. The Dynas mill produces unbleached sack paper saw a
reduction in stock dilution, which resulted in an increase in dry solids in the evaporation
liquor and a reduction of steam consumption by 55%.

6. Orgill, B. “Commercial Utilization of Cold-Blow and Extended-Delignification
     Techniques in Batch Cooking” IPPTA Convention Issue: 57-62 (April 1986).
     [Engl.] Abstract No. 14131

The Sunds Defibrator cold-blow and extended delignification system can be installed and
retrofitted on most existing batch cooking plants. Benefits include steam savings, the
elimination of TRS emissions, and improved washing and pulp quality.

7. “Low-Energy "Cold Blow" Batch Cooking” Papier Carton Cellulose 34, no. 7: 129-
     131 (July 1985). [Fr.] Abstract No. 7570

				
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