Method for preparation of wood cellulose

Claim 1

IN THE PRODUCTION OF PULP OF HIGH-ALPHA LOW PENTOSAN CONTENT FROM WOOD CHIPS IN WHICH WOOD CHIPS ARE SUBJECTED TO PRESTEAMING FOLLOWED BY DIGESTION WITH AN ALKALINE COOKING LIQUOR, THE IMPROVEMENT WHICH COMPRISES SUBJECTING THE CHIPS TO THE DIRECT ACTION OF THE STEAM AT A TEMPERATURE OF FROM 160* TO 200*C., VENTING FROM THE DIGESTER SUBSTANTIALLY CONTINUOUSLY DURING THE PRESTEAMING FROM 500 TO 2000 POUNDS OF STEAM PER TON OF BONE DRY CHIPS, THEREBY MAINTAINING UNIFORM TEMPERATURE CONDITIONS DURING THE PRESTEAMING THROUGHOUT THE DIGESTER AND REMOVING SUCH VOLATILE GASES AS FORM, AND AT THE CONCLUSION OF THE PRESTEAMING RELIEVING THE PRESSURE IN THE DIGESTER TO SUBSTANTIALLY ATMOSPHERIC PRESSURE TO REMOVE SUCH ACIDS AS WERE RELEASED DURING PRESTEAMING, THEREBY REDUCING THE AMOUNT OF CHEMICALS REQUIRED IN THE ALKALINE DIGESTION THAT FOLLOWS.