| 摘要 |
<p>PCT No. PCT/NO89/00051 Sec. 371 Date Dec. 21, 1990 Sec. 102(e) Date Dec. 21, 1990 PCT Filed May 25, 1989 PCT Pub. No. WO89/12716 PCT Pub. Date Dec. 28, 1989.Process for producing pulp suitable as raw material for paper, board or fiberboards and similar products. A pumpable alkaline slurry of fibrous raw material is conducted through a pressurized tube system by the use of pulp pumps, the pressure increasing in steps from the beginning of the process to the end of the process. On its way the slurry is repeatedly dewatered and rediluted with process liquid. An apparatus suitable for being used in carrying out the process comprises a dewatering tube (64) and a dewatering and venting tube (67) arranged centrally and axially within the tube (64) which may be provided with a perforated part (66). The tube (67) is provided with perforations (68) through which gas and liquid from fiber-containing slurry introduced into the outer tube (64) can escape. At the opposite end from the inlet end of the outer tube (64) there is an outlet (72, 65) for thickened fiber-containing slurry.</p> |
