PRODUCING SODA PULP PROM ASPEN. 



33 



cooking conditions on the resultant condensations are shown in figure 

 17. Curves showing the initial volumes of digester liquors for two 

 of the groups of tests are also included in the same figure. 



In the tests employing various proportions of caustic soda, the 

 amount of liquor at the start of cook varied directly with the amount 

 of chemical, as shown by the straight-line curve. The condensation 

 also increased rapidly as the amounts were increased. The down- 

 ward turn in the heavy-line curve for the higher proportions of caustic 

 is caused by the digester becoming filled and overflowing through the 

 top relief during the final stages of cooking. However, the dotted 



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POUNDS NaOH PER POUND OF WOOD 



u^ 40 50 60 70 80 90 K)0 110 

 CONCENTRATION NaOH -GRAMS PER UTER 



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POUNDS NaOH PER POUND OF WOOD 



C 2 4 6 8 10 12 

 (JURATION AT MAX. PRESSURE- HOURS 























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CONCENTRATION NaOH-GRAMS PER LITER 



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70 80 90 100 IK) 120 

 MAX. PRESSURE -PDS. PER SO. IN. 



Fig. 17.— Effects of cooking conditions on initial volume of digester liquors and on condensation of 



steam. 



line shows the corrected curve, taking the overflow into consideration. 

 The rapid increase in the condensation is a natural consequence of 

 increasing the amount of cooking liquor, which has a high specific 

 heat. 



In the tests employing various cooking periods the main influence 

 on steam consumption was the heat lost by radiation, since the 

 initial volumes of digester liquors were constant. The curve in 

 figure 17 representing this effect has been drawn as a straight line 

 to show only the general trend. It will be observed, however, that 

 the platted points occur in two distinct groups. That the reaction 

 between wood and caustic soda is of an exothermic or heat-generating 

 nature may partly explain this arrangement. In the one group, 

 representing the cooks of longer duration, the cooking reaction was 

 31091°— Bull. 80—14 3 



