第二部份 洗涤筛选
Part 2 Washing and Screening
1、 洗涤筛选理论：
1. Theory of washing and screening
1.1 纸浆的洗涤：纸浆的洗涤是制浆过程的一个重要环节，是使浆料与黑液分离的过程，目的在于充分洗净纸浆的同进还要提取具有较高浓度和温度的黑液，供碱回收生产。
1.1 Washing of pulp: washing the pulp is one of the key steps in the pulp making process which is to separate the pulp and black liquor, the purpose is to fully clean the pulp as well as extract the black liquor of high concentration and temperature for the alkali recycle production.
1.1. 1纸浆洗涤干净程度有何影响：纸浆洗涤不净不仅造成化学品的直接损失影响提取率，而且由于过量残碱存在筛选时易起泡沫造成筛选和漂白操作困难。
1.1.1 Effects of cleanness of pulp: unclean pulp will not only cause the direct loss of chemicals, but also cause screening and bleaching difficulties due to too much alkali remnant.
1.1.2、黑液浓度：实际上是表明黑液中因形物的含量通常又以比重或波美度来表示。根据黑液的波美度我们可以得出固形物含量。用15℃下的波美度乘以1.5将获得固形物含量。
1.1.2 Concentration of black liquor: solids content in the black liquor demonstrated with specific gravity or baume degree.15℃ baume times 1.5 will get solids content.
1.1.3、黑液洗涤方式：有挤压和扩散方法。
1.1.3 Washing methods of black liquor: pressing method and proliferation method.
1.1.4、洗涤的影响因素：
1.1.4 Influencing factors of washing:
a、温度、提高温度增加过滤速度和扩散速度加快洗涤过程。
a. Temperature: higher temperature will accelerate the screening & proliferation speed and the washing process.
b、压力 适当增加压力差可加快过滤速度
b. Pressure: adequate higher pressure can accelerate the screening speed.
c、浆层阻力：浆层厚提高了过滤和扩散阻力势必延长洗涤时间降纸洗涤质量。
c. Pulp layer resistance: thicker pulp layer will increase the screening and proliferation resistance which will result in longer washing time and poorer washing quality.
d、纸浆硬度：纸浆硬度大有利过滤但不利于扩散。
d. Hardness of pulp: the higher pulp hardness will facilitate the screening but hinders the proliferation.
1.2、纸浆的筛选。
1.2 Screening of pulp.
1.2.1、筛选的目的是除去纸浆中不符合质量要求的组分，如未蒸介分，节子粗纤维砂粒，小铁块和树脂以降低浆料的尘较度。
1.2.1 The purpose of screening is to remove unqualified constituents of the pulp, such as not steamed constituent, knots, coarse fiber, sands, small iron pieces and resin so as to lower the dirt count of pulp.
1.2.2、筛选设备：
1.2.2 Screening equipments:
a、 除节机（Knot Separator ）筛板孔径Φ8mm筛选面积0.9m2除去大块的节子，石头等。
a. Knot Separator: bore diameter of screen: Φ8mm; screen area: 0.9m2; to remove the big knots and gravels etc.
b、 压力筛（Prinag Screen）筛缝宽度0.2mm筛选面积1.3 m2
0.2mm 0.3 m2
b. Prinag Screen: width of screen seam: 0.2mm; screen area: 1.3m2
0.2mm 0.3 m2
c、节子洗涤器（Knot washer ）筛板孔径Φ8mm筛面积2.1 m2
c. Knot Washer: bore diameter of screen: Φ8mm; screen area: 2.1m2
d、 浆渣洗涤器（Reject Washer ）筛选面积2.1 m2筛孔Φ3mm
d. Reject Washer: screen area: 2.1m2; bore diameter of screen: Φ3mm;
e、 锥形除砂器（Sand separator）根据介质比重不同来除去杂质
e. Sand Separator: remove the impurity according to the difference of media specific gravity.
1.2.3、洗涤设备
1.2.3 Washing equipments
真空洗浆机（Vacuum Washer）3台，面积60m2尺寸Φ3500×5450
转速0.8—3rpm
3 vacuum washer with area of 60m2, dimensions of Φ3500×5450 and rotate speed of 0.8-3rpm.
原理：利用液位差，形成真空度把浆层里的黑液过滤完进行洗涤，我们是采用三段逆流洗涤的方法。
Theory: utilize the difference of liquor level to form vacuum to completely wash the black liquor out of pulp layer, a three-phase adverse current washing method is adopted.
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