GB1228057A - - Google Patents

Abstract

1,228,057. Extraction. R. EICKEMEYER. 14 Oct., 1968 [17 Oct., 1967], No. 48512/68. Heading B1Q. [Also in Divisions C2 and D2] The chemical conversion of cellulose-containing material is effected in a percolator comprising a cylindrical section 1, an upper inlet valve 4, or steam inlet valve 5, a steam exhaust valve 6 and a distributor 4' for liquid and steam, and a lower cone-shaped portion 2 containing a filter divided into vertically superimposed sections 7, 7'. Reagent liquid is introduced below its boiling point through the upper portion of the filter (inlets A) into the percolator, which is at atmospheric pressure or slightly above, in a volume sufficient to cover the cellulose-containing material, whilst at the same time steam at a higher pressure is fed through the lower part of the filter (inlets B) in a quantity to maintain a temperature of at least 100‹C at the upper surface of the liquid in the percolator so as to displace air or other uncondensable gases through exhaust valve 6, whereafter steam is introduced from above (valve 5) at about 1 atmosphere excess pressure, to drain off excess reagent liquid not absorbed by the cellulosecontaining material through openings A and B, and only then is heating to the desired reaction temperature effected by steam introduced through the filter (opening A and/or B). The filters may consist of metal sheets comprising conical holes hung on straps 8, the sections 7 and 7' being separated by sealing ring 9. The distance apart of the holes may decrease from the top to the bottom giving 50-67% more holes in 7' than in 7. In Example 1, beech chips are first treated with 1% H 2 SO 4 to convert hemicelluloses to xylose which is recovered by successive washings with xylose solutions of decreasing sugar concentration derived from preceding percolations and finally with water, the solutions being admitted at the top of the percolator and forced out of the bottom by steam from above; 4% H 2 SO 4 is then used to convert the cellulose to dextrose, recovered in an analogous manner to the xylose leaving a residue of lignin which is discharged through opening 16 after admission of steam from below to disintegrate it, and freed from steam in a cyclone separator. In Example 2, beech chips are treated with nitric acid to hydrolyse hemicellulose to xylose which is recovered in a similar way to Example 1, and the residue is treated with a NaOH/Na 2 S/Na 2 CO 3 solution obtained by the addition of fresh re-agent, or the fused mass obtained from spent lye combustion products, to spent lye to dissolve lignin ("sulphate" process) which is extracted by successive batches of spent lye of decreasing concentration from previous percolations followed by water washing, leaving a residue of wood pulp or cellulose.