造纸用起皱粘缸剂研究进展

起皱可使纸张更加柔软,在生产过程中需使用粘缸剂使纸幅和扬克烘缸贴合紧密,以便刮刀将烘干的纸幅从烘缸上刮下得到皱纹纸.文中介绍了纸张柔软度测试方法的发展、起皱的机理以及其对柔软度的影响,阐述了粘缸剂对起皱过程的重要性.综述了最常使用的粘缸剂-PAE树脂的性能、固化机理及发展以及其他种类粘缸剂的研究现状,最后对粘缸剂的发展...     

改进型Smith-专家PID算法在烘缸温度串级系统上的应用

针对少烘缸或单烘缸纸机的干燥过程具有滞后大、惯性大且非线性的缺点,提出专家PID结合Smith预估器的算法,设计了少烘缸纸机或单烘缸纸机的烘缸温度和蒸汽流量串级控制系统。主控制器是改进的专家PID控制器,利用基于专家经验的知识库在线调整PID参数;对主回路采用改进型Smith预估器,以克服纯滞后对系统稳定性的影响,也解决了Smith预估器对数学模型精确要求的问题。利用MATLAB进行仿真,结果表明:改进型Smith-专家PID算法具有良好的控制品质,具有超调小及响应速度快等动态特性。     

一种新的纸机干燥部蒸汽冷凝水热泵控制系统

简要介绍纸幅干燥原理和热泵节能机理,设计一套基于S7—300PLC的五叠网涂布白板纸机蒸汽冷凝水热力控制系统,阐述具体的控制方案和采用的控制算法,其中主要包括热泵组的压力分段控制和热泵开度的低端选择控制、湿端低温段烘缸组压力回路分段控制、热烘箱二次蒸汽回收压力回路的分程控制和成纸水分的串级控制。实际应用效果表明该控制系统方案是可行的,同时也是有效的。     

纸张湿强剂研究动态

纸张是由纤维素构成的。纤维素是亲水性物质,容易被水润湿和溶胀。当纸张浸水后,其强度大为降低,仅为干纸强度的3％～10％。如果纸张只用于书写和印刷,则湿强度并不重要。但目前纸张的应用范围不断扩展,诸如工业包装纸、食品包装纸、照相纸、滤纸、擦拭用纸以及医用床垫纸等都要求在润湿情况下保持一     

扫描电镜法在检验纸张中的应用研究

对书写类纸张的检验是日常文件检验中的一项重要技术手段,在纸张检验的过程中,有时有必要对书写类纸张的种属类型进行检验,并对疑似同种或同一张纸进行整体及部分的检验。主要研究的是扫描电镜法对书写类纸张的检验,希望可以为纸张检验提供理论支持。     

浆粕烘干机烘缸虹吸管的改进

1烘缸的通汽方式 生产化纤浆粕所使用的抄浆烘干机，其烘缸的加热是在烘缸内通入饱和蒸汽。多烘缸机型的烘缸通汽加热方式，一般是把全部烘缸分为两组，第一组占烘缸总数的85％左右，第二组占15％左右，通汽方法是把原蒸汽通入第一组，没有用完的蒸汽连同冷凝水一齐排入汽水分离器中，分离出来的蒸汽送入第二组烘缸内作为加热蒸汽，没有用完的蒸汽及冷凝水一起排入泠凝水收集容器中。     

一种抄纸过程的DCS

设计了一套经济实用的抄纸过程分布式控制系统（亦称ＤＣＳ）。经由浓度控制、气垫式流浆箱串有控制、定量水分控制等子系统组成。中新推导出的上人有分数时滞的Ｄａｈｌｉｎ控制算法具有良好的抗干扰性及鲁棒性。系统克服了因国产水分仪的性能缺陷而造成的瓶颈,成功地实现了抄纸过程自动控制系统的国产化。本控制系统已投入运行,明显提高了纸张质量。     

成果转让

1 概述 该产品应用于造纸生产,起提高纸张干、湿强度和助滤、助留作用。它具有固化时间快,只需纸机干燥,不需要加热熟化的特点,适合于各种纤维,包括非木质纤维和二次纤维,能起到提高纸张品质,降低造纸成本,减少环境污染的作用。因其提供的湿强度在碱液中全部损失,故其损纸易于处理成浆,不损伤纤维。     

几种银盐照相感光材料的试制

一灯光纸的试制纸张印像纸之能在灯光下感光使用者,称为“灯光纸”,一般是在纸上涂以感光剂而成。这种纸最好是纯由纤维素组成,或含亚硫酸纸浆不多的纸张。印像纸上普通还涂有一层白色硫酸钡作为填充料,叫做“钡地纸”。这种纸密致洁白,没有细纹,我用的是一种光滑细洁的厚道林纸和一种比较平滑的图书纸。薄道林纸太软,张力不够,     

造纸化学助剂

一、概述造纸工业是消耗大量化工原料的一个行业。在造纸过程中,纤维原科、纸浆或制品都需要用各种化学品来处理。除了常用的酸、碱等无机化学品及滑石粉、松香、明矾等,还需在造纸机或涂布机上加入一些辅助的化学药品,它们被统称为“造纸化学助剂”,往往为量很小,但赋予纸张以新的特性。目前在提高纸张的干强度、湿强度,增加滤水性能,增加填料保留率以及用于施胶、柔软、防水、抗油、防霉、消泡、提高纸的表面强度等方面均     

PAPER DRYING: A STRATEGY FOR HIGHER MACHINE SPEED. II. IMPINGEMENT AIR DRYING FOR HYBRID DRYER SECTIONS

For printing and heavier grades, combining cylinder and impingement air drying into a multiple technique dryer section can enable higher productivity through higher machine speed. The large differences in local moisture content and temperature across the sheet which develop quickly under high intensity impingement drying provide the potential for reducing drying time by sheet reversal between impingement drying cylinders. This advantage was determined experimentally under low intensity impingement drying conditions. Use of the micro-scale based McGill dryer simulator for determining the advantage from sheet reversal between impingement drying cylinders was demonstrated for both laboratory and industrial impingement drying intensities. For completing the drying of 205 g/m² linerboard from 0.3 to 0.5 kg/kg dry under 400°C air jets of Re 20000, drying time is about 30% less with sheet reversal between two impingement drying cylinders than for a single, larger diameter cylinder. This extensively validated dryer simulator enables determining advantageous design specifications and operating conditions for hybrid dryer sections involving combinations of cylinder and impingement air drying, a concept with potential to become common industrial practice.     

Spray Drying Performance of a Laboratory Spray Dryer for Tomato Powder Preparation

This work investigates the performance of a spray dryer for tomato powder preparation by spray drying of tomato pulp. Samples of tomato pulp with a 14% constant total solids concentration were used, and a pilot scale spray dryer (Buchi, B-191) with cocurrent operation and a two-fluid nozzle atomizer was employed for the spray drying process. Twenty-four different experiments were conducted keeping constant the feed rate, the feed temperature, and the atomizer pressure, and varying the compressed air flow rate, the flow rate of drying rate, and the air inlet temperature. In each experiment the air outlet temperature was recorded. Data for the residue remaining in the chamber and cyclone walls was gathered and two types of efficiencies were calculated as an indication of the spray dryer performance. Analysis of experimental data yielded correlations between residue accumulation and the variable operating conditions. The same operating parameters had a great influence on the air outlet temperature whereas temperature deviations were observed comparing measured air outlet temperatures with corresponding outlet adiabatic saturation temperatures.     

PAPER DRYING: A STRATEGY FOR HIGHER MACHINE SPEED. I. THROUGH AIR DRYING FOR HYBRID DRYER SECTIONS

For all grades of uncoated paper heavier than tissue, the search for new drying technology has recently become directed towards finding combinations of air drying with cylinder drying which have advantageous techno-economic characteristics. Air drying exists in two forms, through air drying and impingement air drying. An advantage intrinsic to through air drying is exceptionally high drying rates because the distance for heat and mass transport processes is reduced from the thickness of the sheet to the dimensions of pores and fibres. Use of through air drying combined with traditional cylinder drying into multiple technique dryer sections is constrained by two basic characteristics, the cost of the pressure drop for air flow through the sheet, and the tendency for through air drying to produce undesirable local moisture nonuniformity during drying. These two characteristics of through drying are documented and strategies for limiting these disadvantages are identified.     

Enhancement of Drying Rate in Paper Machines with Multi-Functional Radial Jet Reattachment Blow Boxes — Theoretical Analysis

Multi-functional radial jet reattachment blow boxes deliver a dry air into the pockets of the dryer section of a paper machine by impinging directly onto the unsuppned sheet in the open diaw. The air flow also maintains or improves the sheet swbility.

The iadial jet reattachment blow box technology pmvides a significant enhancement in drying rates. The theoretical drying results are presented in terms of average drying rates, moisture and temperature pmfiles along the drying section with and without the presence of the multi-functional radial jet reaaachment blow boxes. The thcorclical results indicate that enhancements of drying rates within the range of 8% to 25% are feasible depending on ihe operating conditions and machine configuration.     

PAPER DRYING: A STRATEGY FOR HIGHER MACHINE SPEED. I. THROUGH AIR DRYING FOR HYBRID DRYER SECTIONS

For all grades of uncoated paper heavier than tissue, the search for new drying technology has recently become directed towards finding combinations of air drying with cylinder drying which have advantageous techno-economic characteristics. Air drying exists in two forms, through air drying and impingement air drying. An advantage intrinsic to through air drying is exceptionally high drying rates because the distance for heat and mass transport processes is reduced from the thickness of the sheet to the dimensions of pores and fibres. Use of through air drying combined with traditional cylinder drying into multiple technique dryer sections is constrained by two basic characteristics, the cost of the pressure drop for air flow through the sheet, and the tendency for through air drying to produce undesirable local moisture nonuniformity during drying. These two characteristics of through drying are documented and strategies for limiting these disadvantages are identified.     

DRYING OF PULP AND PAPER SLUDGE IN A PULSED FLUID BED DRYER

Hydrodynamics and drying kinetics for the pulp and paper primary sludge dried in a pulsed fluid bed dryer with relocated air stream are presented. Batch experiments have indicated that drying of disintegrated sludge to the required 12% moisture content takes place during the first drying period at practically constant material temperature close to the wet bulb temperature with respect to the inlet air conditions. Equations were developed for pressure drop, minimum pulsed-fluidization velocity, dynamic bed height, and volumetric mass transfer coefficient. Continuous experiments under drying conditions determined from the average residence time concept have confirmed that transportation of disintegrated sludge along the dryer follows the plug flow model.     

Spray Drying of Tomato Pulp: Effect of Feed Concentration

The effect of feed concentration on spray drying of tomato pulp preconcentrated to 78, 82, and 86% wet basis is investigated in two spray drying systems: a pilot scale spray dryer (Buchi, B-191) with cocurrent regime and a two-fluid nozzle atomizer, and the same connected with an absorption air dryer (Ultrapac 2000). Data for the residue on the chamber and cyclone walls were gathered and two types of efficiencies were calculated as an indication of the spray dryer performance. Tomato powders were analyzed for moisture, particle size, and bulk density. In both spray drying systems, with increases in tomato pulp concentration overall thermal efficiency, evaporative efficiency, material loss in the cyclone, powder moisture content, and bulk density decreased, whereas powder particle size increased. On the contrary, the effect of feed solids content on residue formation and product recovery was dependent on the drying medium. In the standard dryer, the higher the feed concentration, the higher was the residue accumulation, and the lower the product recovery, whereas in the modified system increases in pulp concentration resulted in lower residue formations and higher product yields.     

EFFECT OF BLOW BOXES ON EVAPORATION DURING CYLINDER CONTACT IN A PAPER MACHINE DRYER SECTION

In this paper an inexpensive configuration for a cylinder blow box (CBB) and its effect on the evaporation rate are described. The objective of this work was to determine the effect of the blow boxes on drying intensity on a paper machine. The pilot machine trials were simulated with a computer program. Based on these results two cases were simulated for a commercial paper machine with and without blow boxes on single cylinders. The results revealed that when using the blow boxes on single cylinders, the drying rate can be increased by up to 15%. The potential for using this kind of configuration is biggest at the beginning of a dryer section. A simple construction of blow boxes makes this technique useful especially in boosting the drying performance of older paper and board machines. The exhaust air from the boxes can be utilized in ventilation of dryer pockets.     

Spray Drying Performance of a Laboratory Spray Dryer for Tomato Powder Preparation

Abstract

This work investigates the performance of a spray dryer for tomato powder preparation by spray drying of tomato pulp. Samples of tomato pulp with a 14% constant total solids concentration were used, and a pilot scale spray dryer (Buchi, B-191) with cocurrent operation and a two-fluid nozzle atomizer was employed for the spray drying process. Twenty-four different experiments were conducted keeping constant the feed rate, the feed temperature, and the atomizer pressure, and varying the compressed air flow rate, the flow rate of drying rate, and the air inlet temperature. In each experiment the air outlet temperature was recorded. Data for the residue remaining in the chamber and cyclone walls was gathered and two types of efficiencies were calculated as an indication of the spray dryer performance. Analysis of experimental data yielded correlations between residue accumulation and the variable operating conditions. The same operating parameters had a great influence on the air outlet temperature whereas temperature deviations were observed comparing measured air outlet temperatures with corresponding outlet adiabatic saturation temperatures.     

Enhancement of Drying Rate in Paper Machines with Multi-Functional Radial Jet Reattachment Blow Boxes — Theoretical Analysis

ABSTRACT

Multi-functional radial jet reattachment blow boxes deliver a dry air into the pockets of the dryer section of a paper machine by impinging directly onto the unsuppned sheet in the open diaw. The air flow also maintains or improves the sheet swbility.

The iadial jet reattachment blow box technology pmvides a significant enhancement in drying rates. The theoretical drying results are presented in terms of average drying rates, moisture and temperature pmfiles along the drying section with and without the presence of the multi-functional radial jet reaaachment blow boxes. The thcorclical results indicate that enhancements of drying rates within the range of 8% to 25% are feasible depending on ihe operating conditions and machine configuration.