| 摘要 |
In the production of pulp from ligno-cellulosic material such as wood chips the material is defibred in the presence of steam at temperatures above 100 DEG C. and corresponding pressures and is then blown successively by means only of the steam pressure to two or more refining stations the pulp being diluted with water before each refining station. Chips of fir wood which have been moistened with steam and impregnated with an aqueous solution of sodium sulphite are fed by a hopper 10 and feeder 12 to a vessel 14 to which steam is admitted through a pipe 16, the pressure in the vessel 14 being 8 atmospheres gauge. The chips are fed continuously to a disc-type defibrator 18 and thence the pulp at a consistency of 30% is blown via a valve 22 and conduit 24 to a disc-type refiner 26. Water at a temperature of about 100 DEG C. is added to the pulp just prior to its entry to the refiner 26 the concentration and temperature of the pulp being reduced thereby to e.g. 20% and 135-140 DEG C. respectively. The pressure in the refiner 26 is e.g. 3 atmospheres gauge. The pulp then passes to a further refiner 40 accompanied by further dilution and reduction in pressure and temperature and is discharged therefrom to a plup bin 50 from which it may be drawn by a pump 54 as desired. Reference is made to the possibility of adding various chemicals such as sodium sulphite, sodium hydrosulphite, sodium or hydrogen peroxide or sulphur dioxide in one or more of the refining stages. Recovered waste liquid from the process may be used to dilute the pulp before entry to the refiners instead of water. The defibrator may be of the kind disclosed in U.S.A. Specification 2,964,250. |
