Quantifying the Pulp Refining Process

Pulp refining action is commonly described by one or more quantitative parameters to enable comparisons among refiners and optimization of individual refiners. Specific refining energy and refining intensity are the two most commonly used parameters. Both are energy-based,but recent work by this author has shown that additional parameters based on force are of benefit. This paper reviews the background and key aspects of this work.

Fibre Treatment Uniformity in Pulp Refining

This paper explores implications of previous work which suggested that pulp refining is achieved by a small number of impacts.As a consequence,the purpose of multiple bar crossings in refiners is to expose many fibres to a few effective cycles,not to impose many cycles on each fibre.Based on this postulate,tensile strength increase was found to be well described by a cumulative probability equation having two parameters:(a) number of bar crossings and(b) probability of a successful refining outcome at each crossing.In this paper,this concept further with additional refiner data was explored and the link between the probability term and measurable refiner variables was examined.By proposing the possibility,these two parameters may be a desirable alternative to specific energy and specific edge load for characterizing refining action.

Study on Refining Performances in Chemi-mechanical Pulping of Mixed Poplar and Eucalypt Woodchips

The refining performances of mixed poplar and eucalyptwoodchips(mixture ratio 6:4)were investigated at medium and highpulp consistency via chemi-mechanical pulping(CMP).The specificrefining energy consumption(SEC),fiber fraction proportion,andCanadian standard freeness(CSF)were determined to evaluate the effectsof pulp consistency and NaOH dosage on the refining performancesof mixed poplar and eucalypt woodchips.While the dosage of NaOHfor impregnation was maintained constant,the SEC and shive contentincreased with increasing pulp consistency.Different fractions obtainedfrom the Bauer-McNett classifier showed that higher pulp consistencycould be expected to yield more long fibers and shive in the stock.Upon increasing the NaOH dosage,the shive content and SEC reducedsignificantly.When the NaOH dosage was increased to 6%,the resultsindicated that it was difficult to reduce the shive content to less than 1%athigh pulp consistencies(25%~35%),whereas 0.18%shive fraction couldbe achieved at a medium pulp consistency(15%).

Effect of Refiner Plate Bar Angle and Pulp Properties on the Low Consistency Refining Efficiency in Terms of Power Consumption

Power consumption is the energy source of the impact on fibers or pulp during low-consistency(LC)pulp refining,and the strength of refining affects refining quality and efficiency.The pulp properties,operating parameters,and bar parameters of the refiner plates are important parameters affecting refining efficiency,which can be defined as the ratio of net to total refining power.In this study,LC refining trials for pulps with different consistencies and fiber lengths were conducted using five isometric straightbar plates with different bar angles to explore the influences of the plate bar angle and pulp properties on the no-load power,impact capacity on fibers and refining efficiency.It was found that the no-load power of the LC refining process decreased with an increase in the plate bar angle while increased when pulp with higher consistency was refined under the same refining conditions.However,the effect of pulp consistency on the no-load power can be neglected when refining is conducted using plates with larger bar angles.Meanwhile,a critical bar angle for straight-bar plates in LC refining may exist,which has the strongest impact on the pulp and highest refining efficiency under the same refining conditions.In addition,the impact capacity of the plate on the pulp and refining efficiency in LC refining can be enhanced by appropriately increasing the pulp consistency and average fiber length when the bar angle of the refiner plate with a sector angle of 40°is less than 30°.Therefore,the efficiency and power consumption of the LC refining process can be adjusted by optimizing the pulp consistency and bar parameters of the refining plates.

REFINING BEHAVIOUR OF BAMBOO LONG FIBRE FRACTION PULP

Refining of pulp significantly contributes to papermaking process by affecting the runnability of the stock and quality of end product. The greater the production rates of a paper, the greater are the effects of machine downtime through breaks. A correct approach towards refining treatment is very essential for energy savings and product with desired properties. Papermakers are being encouraged to use non-wood fibres for a variety of reasons - the environment, changing agricultural policy and long-term fibre supply. Compared with wood fibres, there is less knowledge on how to treat non-wood fibres for optimum performance. Laboratory studies aimed at understanding the behaviour of unbleached bamboo long fibre fraction pulp on refining in Escher Wyss Laborefiner under simulated process conditions included investigations of the important parameters like wet web tensile, wet web elongation, water retention value and paper strength properties. The paper describes the influence of two specific edge loads, 1000 and 1500 Ws/km on refining of pulp. Bamboo long fibre fraction pulp responds better to lower intensity refining to develop pulp strength.

Simulation of the Flow Conditions in Different Types of Bar Structures of Disc Refiner

Disc refiner is a critical equipment in the pulping and papermaking industry, pulp is refined in the refining zone, and different bar structures of refining disc constitute the different refining zones. With the use of the 3D modeling software SOLIDWORKS, five different refining discs that are commonly used in low consistency pulping, were built. The five refining discs were simulated and analyzed using the Computational Fluid Dynamics(CFD)software. The distribution of pulp velocity and surface shear stress, which is displayed between the bar and groove structures, can indirectly show the stress conditions on the refining discs. This paper provides a theoretical basis for research on the bar and groove failure of the refining discs.

High Performance of Paper Strength and Energy Savings in OCC Pulp Papermaking via MFC Addition

Fiber screen fractionation of recycled old corrugated container(OCC)pulp and subsequent targeted processing of each fraction can lead to higher fiber quality,more uniform pulp,and increased handsheet strength and surface smoothness.This pilot-scale study evaluates the benefits of fiber fractionation using a pressure screen prior to low consistency(LC)refining.A 0.81-mm smooth holed screen cylinder is utilized,and two refiner plate patterns are adopted(wide 0.99 km/rev BEL and interim 2.01 km/rev BEL).Here,LC-refined reject fractions are mixed with the created microfibrillated cellulose(MFC),and the mixed pulp and paper qualities are compared with no-MFC OCC pulps.The results indicate that the highest tensile strength of the handsheet is obtained by the addition of MFC to the fractionated refined OCC pulp compared to the unfractionated refined OCC and primary OCC pulps at a given specific energy.Furthermore,the experimental approach adopted in this study can be used to optimize recycled OCC pulping systems.Overall,the results indicate that fractionated LC refining plus MFC addition provides higher pulp and paper qualities and the potential for saving energy to reach the desired tensile strength of the OCC pulp.

PFI磨预处理提高桉木浆纤维反应活性的研究

采用PFI磨对桉木漂白化学浆进行预处理后,以丙烯酰氯为酯化试剂,在球磨机中进行酯化反应,通过纤维质量分析仪、光学显微镜、X射线衍射(XRD)和傅里叶红外光谱(FT-IR)对纤维的形貌和结构进行了分析,并进一步考察了酯化条件对纤维素反应活性的影响。研究结果表明:随着PFI磨转数的增加,纤维长度、纤维宽度减小,细小纤维比例显著提高,由19.86%增大至38.47%。经PFI磨打浆后,纸浆纤维表面纤丝化明显,其结晶区域部分遭破坏,结晶度由72.7%降低至66.9%;XRD结果表明:反应过程中酯化产物的结晶结构发生了改变。FT-IR结果表明:PFI磨解纤维与丙烯酰氯经球磨发生酯化反应得到丙烯酰基纤维素。酯化产物的取代度(D_(S))随着PFI磨转数的增加而增大;与未经预处理纤维相比,反应产物的D_(S)明显增加,最高可达2.38,此时的反应条件为PFI磨预处理24000 r,纤维素与丙烯酰氯的物质的量比1∶6,球磨反应时间48 h。

改善加热不燃烧型烟草薄片物理性能的研究

加热不燃烧型烟草薄片是一种新型烟草薄片,其制备方法主要包括稠浆法、辊压法、造纸法。为保证烟草薄片的良好成形及耐加工性,需添加一定量的木浆纤维。本研究探究了木浆纤维在稠浆法加热不燃烧型烟草薄片中的应用,考察了木浆纤维打浆度和添加量对稠浆性能和烟草薄片物理性能的影响。研究表明,增加木浆纤维打浆度有利于降低稠浆黏度,木浆纤维的打浆度为49°SR时,烟草薄片的力学性能相对较好;木浆纤维添加量在2%~5%时,烟草薄片力学强度随着木浆添加量的增加而增加,抗张指数最高可达3.62 N·m/g。

降低磨浆能耗的杨木化机浆制浆技术

分别对杨木化机浆的高浓磨浆工艺、磨浆过程/段间加药工艺及两段APMP工艺的磨浆性能进行了研究。研究结果表明:高浓磨浆工艺可以大大改善纸浆质量,增加撕裂强度,改善滤水性能。磨浆过程/段间加药工艺,可以在改善纸浆质量的同时大幅度降低磨浆能耗,加药位置越靠前节能增强效果越好;磨浆过程中加药的浆可漂性能良好,H2O2用量3%时纸浆白度可达74.4%～76.3%ISO,后经H2O2(用量2%)补充漂白,白度可达81%ISO以上。

ZDPM型液压盘磨机中浓打浆生产应用——草浆、废纸浆中浓打浆的使用效果及机理初探

从打浆后成浆质量、纸产品性能、打浆能耗等方面探讨了草浆、废纸浆中浓打浆的生产使用效果 ;在中浓打浆机理方面提出了“内摩擦效应” ,丰富了打浆理论 ,阐述了中浓打浆具有优越性的原因。

办公废纸脱墨工艺的研究

分别从高温高浓碎解和低浓碎解两条工艺路线出发，对办公废纸的脱墨工艺进行了初步研究。试验结果表明，碎浆温度和浓度对浮选脱墨效率有很大影响。经高温高浓碎解浮选处理可得到较高质量的脱墨浆；低浓碎解浮选流程的脱墨效果较差，但与后续的高浓磨浆和后浮选工序结合起来后，脱墨效率显著提高，可获得油墨尘埃度很低的脱墨浆。

盘式磨浆机技术研究进展与趋势

着重阐述盘式磨浆机设计制造、微观磨浆机理、运行参数测量、运行控制、设备维护等方面技术研究的发展过程和国内外技术研究的最新进展,同时对今后的研究方向提出展望。

双螺旋辊式新型磨浆机及其应用

简述了双螺旋辊式磨浆机的磨浆流程 ;探讨了平行、啮合、同向旋转双螺旋辊磨浆的机理 ;简单列举了国内外应用实例。生产实践表明 ,此种磨浆机将以其低能耗、高磨浆质量和多功能成为新一代磨浆设备。

双螺杆磨浆机螺纹参数设计与研究

双螺杆磨浆机是一种同向旋转、啮合型磨浆专用的双螺杆挤出机。根据相对运动原理得到的双螺杆磨浆机的螺纹曲线比较复杂,不利于加工制造。本课题采用逼近方法将双螺杆的螺纹曲线简化成梯形,然后通过双螺杆间物料流量计算对螺棱顶宽的作用进行了分析,提出螺棱顶宽的选择范围;讨论了变螺距螺杆体积压缩比的计算方法。对双螺杆磨浆机螺纹曲线的简化不仅可满足双螺杆的啮合作用,保证生产效率,而且有利于螺纹的切削加工。

酶预处理对漂白针叶木浆性能和打浆能耗的影响

采用纤维素酶对漂白针叶木浆进行预处理,研究了酶预处理对浆料打浆性能和成纸强度性能的影响。结果表明,酶预处理后,漂白针叶木浆纤维的表面起毛且长度减小,细小纤维含量增加。对酶预处理后浆料进行PFI磨打浆,当打浆5000或10000转时,随着酶用量的增加,浆料游离度逐渐降低,表明酶预处理可降低打浆能耗,但打浆过程中纤维易被切断。打浆与适当的酶预处理相结合,可提高成纸强度性能,当打浆500、2000和5000转时,酶用量为0.01 U/g浆料的成纸抗张指数较未经酶预处理浆料分别提高了54.6%、60.3%和48.5%。

针叶木浆磨浆过程中浆料的流动、纤维受力及形变

分析了磨浆过程中浆料的流动形式,磨齿作用力,纤维受力、形变和相应的磨浆效果,探讨了磨齿前刃对纤维的作用力,讨论了纤维切断、纤维分层和内部细纤维化、纤维"剥皮"及表面细纤维化的原因。

杨木加工剩余物制漂白化学机械浆及配抄轻型纸的研究

以杨木加工剩余物为原料，进行了漂白化学机械法制浆性能及配抄轻型纸的研究。研究结果表明：H2O2用量5．0％，NaOH用量4．5％，在此条件下制得的漂白化机浆白度可以达到78％（ISO）以上；加拿大游离度为100mL（CSF）时，纸浆的松厚度达到2．1cm^3／g以上，抗张强度达38N·m／g以上，以该条件制得的漂白化机浆配以10％。20％的漂白针叶木浆，抄造的轻型纸质量指标可以达到轻工行业标准（QB／T2809-2006）中轻型纸的质量指标要求。

低浓盘磨机特定刃边载荷的计算

本文推导了在低浓度情况下盘磨机打浆刃边特定载荷的计算模型。由此 ,可以合理地选择磨片的几何尺寸 :剪切角、分区角及凸棱的形状 。

打浆参数对绝缘纸力学和电气性能的影响

为深入研究打浆过程中打浆时间和打浆压力对绝缘纸性能的影响,制备了不同打浆时间和打浆压力的绝缘纸,并测试其基础理化特性、力学特性及电气性能。结果表明:随着打浆时间的增加,绝缘纸的力学性能、交流电气强度和油纸绝缘的交流电气强度均不断提高并逐步趋于稳定,打浆时间的变化对于绝缘纸的电导特性没有明显的影响。随着打浆压力的增加,绝缘纸的力学性能不断提高并趋于稳定,其交流电气强度和油纸绝缘的交流电气强度均升高且没有减缓趋势。绝缘纸的体积电阻率随着打浆压力增加而不断减小。扫描电镜结果表明,打浆度相同而打浆参数不同的绝缘纸电气强度存在差异,这是由于纤维形态和分丝帚化程度不同。