Drying of Uncoated Paper with Gas-Fired Infrared Emitters—Optimum Emitters' Location Within a Paper Machine Drying Section

This article theoretically investigates the drying of uncoated paper with gas-fired infrared (IR) emitters installed within the drying section of a given commercial paper machine. Specifically, it presents the ideal location of two opposing IR emitters within the drying section. The ideal location of the two opposing IR emitters corresponds to the highest machine speed with specified average moisture content of paper sheet at the end of the drying section. This article also presents the average evaporation rate, temperature, and moisture content of the paper sheet as it travels through the drying section with the two opposing IR emitters operating at the optimum location. In addition, the temperature and moisture profiles in the sheet thickness direction, before and after the IR emitters, are provided. This article is not concerned with the potential effects of drying with IR emitters on paper sheet properties and machine runnability issues.     

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。     

利用废气余热改造解冻库热源

利用废气热处理洗精煤，改造解冻库热源，不仅节约了能源，而且减少了废气的排放，产生了可观的环保效益。     

Dimensioning of Paper Machine Heat Recovery Recuperators

ABSTRACT

Designs of heat exchangers for heat recovery from humid air are described. A mathematical model for heat transfer with simultaneous mass transfer is constructed, based on heat and mass balances. Methods for solution are shown for two cases: 1. The water on the exhaust side of the heating surface is only condensate, whose heat content may be neglected. Also, the case of only partially condensing heat transfer surface is discussed. 2. The heating surface is flushed with abundant water. - Each case is illuminated with a calculation example.     

油气集输过程中低温余热利用热泵技术的概述

当前在油气集输系统中,低温(40~50℃)余热资源非常的丰富,造成了很大能源浪费和热"污染"。改善能源的利用效率,对于解决能源危机非常的关键。热泵是油气集输系统中低温余热进行回收的核心装置,其不仅能够提高能源品味,还具有操作简单,技术较成熟的特点。分析了油气集输系统的用能状况和能源消耗的原因,还论述了低温余热回收热泵技术和对热泵市场进行介绍。     

Three-Layer Model for Drying of Coating Applied on Silicone-Coated Paper

Upon application of water based coating onto silicone-coated paper and during the subsequent drying process, the water permeates through the silicone layer into the paper substrate. At the same time, water evaporates from both the surface of the coated layer and throughout the paper layer. Initially, the evaporation rate from the wet coating surface may be dominant, but at longer times the bulk evaporation from the paper can dominate. Here a three-layer diffusion model for such a system is developed. Solutions obtained by Galerkin's method with finite element basis functions show that the hygroscopic nature of the paper leads to low drying rates at low moisture contents. Further, the model predicts that initially the coating dries to a moderately low residual moisture concentration faster than a coating applied on an impermeable substrate. However, at longer times, the predicted residual moisture of coatings applied on silicon-coated paper is higher than for a coating applied on an impermeable substrate.     

Three-Layer Model for Drying of Coating Applied on Silicone-Coated Paper

Abstract

Upon application of water based coating onto silicone-coated paper and during the subsequent drying process, the water permeates through the silicone layer into the paper substrate. At the same time, water evaporates from both the surface of the coated layer and throughout the paper layer. Initially, the evaporation rate from the wet coating surface may be dominant, but at longer times the bulk evaporation from the paper can dominate. Here a three-layer diffusion model for such a system is developed. Solutions obtained by Galerkin's method with finite element basis functions show that the hygroscopic nature of the paper leads to low drying rates at low moisture contents. Further, the model predicts that initially the coating dries to a moderately low residual moisture concentration faster than a coating applied on an impermeable substrate. However, at longer times, the predicted residual moisture of coatings applied on silicon-coated paper is higher than for a coating applied on an impermeable substrate.     

High Intensity Drying of M.G. Paper

ABSTRACT

The technological properties of paper are strongly influenced by the drying conditions. This is the case in particular with M.G. paper and machine performance is limited largely for quality reasons. Therefore, the question as to which extent the drying conditions influence the process of drying and the paper quality is of major importance for industry.

Unlike the results already published, tests were carried out with a laboratory machine operating on a continuous basis, with high drying rates, short retention time and application of combined contact/ convectional drying. The kinds of stock used were waste paper containing wood, bleached long-fiber magnefite pulp and unbleached long-fiber sulphate pulp with a basis weight ranging between 37 and 75 g/m2.     

Mathematical Modeling of Drying Processes of Selected Fruits and Vegetables

This study investigates the behavior of fruit and vegetable samples during drying. The experimental data are fitted to several different thin-layer drying models. Regression analysis is used to determine model parameters, while statistical indicators serve to evaluate the goodness of fit. The power function model gives the best fit for all examined samples. Based on this model, different drying and heat storage technologies can be combined to ensure that the required residual moisture content of an agricultural product is reached. It is demonstrated on the case of a specific Togolese processing plant that under favorable conditions, fossil fuel consumption can be decreased by 33 %.     

余热发电项目中预热器级数的选择

新型干法水泥生产线的窑尾废气温度决定着余热发电系统的发电效率。窑尾废气温度高对余热发电有利,但耗煤量增大;窑尾废气温度低,耗煤量减少,又不利于余热发电。本文以池州海螺和唐山冀东两厂的实际生产情况为例,通过煤电比来比较余热发电项目中是采用四级预热器合理还是五级预热器合理。     

余热锅炉在热回收焦炉上的应用

介绍了用余热锅炉技术从热回收焦炉烟气中回收余热生产蒸汽的可行性与设计过程，分析了应用余热锅炉后的经济和环保效益。     

Process Parameters Optimization for Energy Saving in Paper Machine Dryer Section

Due to high energy consumption in the Chinese paper industry, this study considers higher-energy efficiency for the multicylinder dryer section of paper machines. A common situation in the Chinese paper industry is that energy is consumed in extensive mode. In order to improve the energy efficiency of the paper machine dryer section, deeper analysis and optimization of process parameters are necessary.

A NLP optimization method is developed for integration of steam system and air system to reduce the steam consumption and decrease the loads of centrifugal blowers in the multicylinder dryer section of a paper machine. Equality constraints of the optimization model are extracted from different process modules based on material and energy balance. Inequality constraints are from the production capacity, operating condition, etc. Two illustrative examples are presented in this paper. The results show that the optimization model is adaptive and convenient for application. For a newsprint machine, less dry air and steam are used and the energy consumption can be reduced by about 8% in the dryer section. Applied on a linerboard machine which has surface sizing, the method can reduce the energy consumption by 5.6%.     

纸张脉动燃烧尾气冲击流干燥过程的实验研究

脉动燃烧因其传热效率高、结构紧凑、环境污染小等优点而广泛应用于生产生活中,冲击干燥同样也能形成强烈的热质交换,本文将上述两种干燥技术结合应用。为了探讨脉动燃烧尾气冲击流干燥的性能,研制了小型Helmh01tz脉动燃烧器,并对脉动燃烧尾气冲击流干燥技术应用于纸张的干燥过程进行了实验研究。分析了气流辐射半径和燃料流量两个参数对干燥过程的影响,可以看出随着气流辐射半径的增加,干燥速度降低。此外还对不同干燥条件下的纸张干燥时间进行了估计,为实际生产提供参考。     

干燥用振荡流热管强化传热研究

振荡流热管（OFHP）在干燥领域有广阔的应用前景。提出了两种强化振荡流热管传热过程的方法：①用脉冲加热代替传统的连续加热；②采用非均匀热管流通截面。实验结果表明，这两种方法都能增强热管内的振荡过程，并使传热性能显著改善。脉冲加热的振荡流热管比相同功率下连续加热时的传热热流量提高15％～38％，当量热导率提高12％～63％。当加热功率大于100W时，非均匀截面振荡流热管比均匀截面振荡流热管的热流量和当量热导率也有明显提高。     

造纸制浆污泥由蚯蚓处理或是干化处理的探讨

从蚯蚓处理制浆污泥的流程和空心桨叶干燥机处理流程进行探讨对比,蚯蚓处理污泥既节能又环保,但占地面积大;空心桨叶干燥机处理污泥不节能,但占地面积小.通过讨论,对大规模处理污泥,建议采用蚯蚓处理污泥,处理后的蚯蚓粪用作有机肥.     

机床涂装工艺特点及设备选择

论述了机床涂装的特点、工艺流程及工艺分析,提出了机床涂装的设备选择方法,特别介绍了移动式喷漆室的结构的特点及其应用。     

流态化干燥过程的分析

通过物料在流化床干燥器上的热态实验,找到了对物料干燥过程产生影响的因素,根据实验数据和理论分析给出了应采取的有利措施。     

太阳能相变储热在木材干燥中应用的初步研究

针对木材太阳能干燥间歇性的不足,在原有太阳能干燥装置的基础上,增设了多管道叉排石蜡相变储热系统。研究结果表明,随着储热系统管排数的增加（5、7、9、11排）,其放热时间逐渐缩短,换热系数呈现增加趋势,平均值分别为17．8、22．1、24．7、26．4W／（m^2·℃）;在其它参数相同的条件下,当管排数不大于5时,储热温度对换热系数的影响不大,但当管排数大于11,储热系统显热储存的热量就不能够忽略;在其它参数相同的条件下,随着风速的增加,换热系数呈现增长趋势,风速为1．0、1．5和2．0m／s时,放热速率的比值为0．89：0．94：1。     

三角枫在干燥条件下的诱发变色过程

三角枫是一种易变色的木材，干燥过程中的变色不易预防；若能使三角枫干燥后得到更为理想的颜色，则可获得更为广泛的应用。通过对三角枫在不同干燥工艺条件下变色过程的研究以及红外光谱与扫描电镜分析，得出了三角枫干燥过程中的最佳诱发变色条件和诱发变色机理。研究结果表明，三角枫在干燥过程中的诱发变色是可行的。三角枫干燥过程的诱发变色机理为：①高温、高湿加速了三角枫中多元酚类物质以及无色花色素与单宁等的氧化反应，使三角枫发生红色变色；②三角枫经饱和蒸汽处理，羟基-OH经氧化转化为羰基-C=O、羧基-COOH、酯基和酮基等，使三角枫发生变色。