Abstract
Some practical cooking conditions on the manufacture of SCP from beech were studied, and the results obtained are as follows:
1) In case the yields of pulps are about 65%, the cooking temperature as high as 195°C makes the cooking velocity so large that the operation of practical cookings may become difficult. The tendency are that cooking at the higher temperature give pulps the higher Roe numbers, the lower pentosan contents and smaller mechanical strengths.
2) In case of under the same cooking conditions, it was shown that the cookings in denser liquid results the lower yields of pulps.
3) At the lower temperatures, it is possible to obtain a normal cooking result using the liquid containing SO2 as low as 1.5%, when the liquid ratio is 5:1.
4) Compared with Na base process, NH3 base process shows some larger cooking velocity and gives pulps lower brightness, the same Roe numbers, lower pentosan contents and less mechanical strengths.
Consequently, on the manufacture of SCP from beech, it is concluded that the practical upper limit of cooking temperature is 185°C and the concentration of liquid may be determined by the qualities of pulps within the range of 1.5_??_2.5% SO2.
