过厚木片对硬质纤维板浆料特性的影响

纤维板原料的多样性,影响了木片规格尺寸的均匀性。为了获得长度和厚度均匀的木片,须对木片进行长度和厚度的筛选。木片厚度筛选已成功地运用于瑞典的纸浆和造纸工业,但木片的厚度筛选在纤维板工业极为罕见。本文阐述原料中过厚木片的含量对纤维板浆料特性的影响。过厚木片的含量分别为0％、10％、30％和50％。制浆在中间试验厂进行,除了蒸汽压力保持不变外,其他热磨工艺参数为变量。对浆料特性的评定结果表明:纤维得率随着过厚木片含量的增加而降低;过厚木片的含量对纤维分离度和粗纤维含量没有显著影响,而对纤维筛分的分布稍有影响。因中间试验厂制浆时的动力消耗大大地高于工厂制浆时的动力消耗,因此过厚木片的含量对制浆时动力消耗的影响,从本研究难以得出结论。

THE EFFECT OF OVERTHICK CHIPS ON PULP CHARACTERISTICS FOR HARDBOARD

The hardboard industry in Sweden faces problem with an increasinglyvarying raw materials. One means to geta more even raw materil is to try thickness screening which has been successfully used in the pulp and paper industry. In this study the effect of a sequential addition of varying overthick chips, amounting from 0 % to 50%was evaluated. Five types of pulp were produced in a pilot scale under different preheating times, disc clearance, screw feeding speeds at a constant steam pressure, 7 kg/cm.The results indicate that the pulp yield increase with decreasing content of overthick chips. At 1 minute preheating time, the increase in pulp is about 0.5% when the overthick chip content cutdown from 0% to 10%, thus reducing both the raw material cost and the BOD of the fiberboard mill effluent.No significant effect of overthick chips was found on pulp drain-ability energy consumption and shives content. However, it should be pointed out that the energy consumption for defibrating in pilot plant is higher than in fiber board industry. Therefore the effect on energy consumption is very hard to evaluate on a pilot plant scale.The results also show that only a little profit could be obtained through screening overthick chip in the fiberboard industry. However, this profit from increasing pulp yield and probably also a more uniform defibration with low content of overthick chips will enhance the fiberboard industry to control its chipping system in order to reduce the amount of overthick chips.