OptiDry Twin冲击式干燥

本文以OptiDry Twin为主,介绍了一种新型的纸页干燥技术——冲击式干燥。这种技术对干燥部的初期干燥尤其有效,其突出的干燥能力和优化的牵引力控制有助于改善纸机运行性能、提高产品质量和车速,同时具有良好的经济性。     

OptiDry干燥技术的发展

介绍了OptiDry、OptiDry Twin,OptiDry Vertical等先进干燥技术的发展、性能及特点。     

基于工艺流程的纸机干燥部建模与模拟

基于三段通汽式干燥部工艺流程,在“输入已知、输出未知”和“先烘缸、再通风、后纸张”的原则指导下,以烘缸组为最小建模单元,根据序贯模块法的基本思路,构建了纸机干燥部的静态模型。以某新闻纸机干燥部为对象进行模拟,给出了进出各模块的物流和能流信息,模拟结果与该纸机实际运行情况基本一致。该模型符合纸机干燥部工艺流程,可以用来模拟各模块之间的物流和能流信息,便于为干燥部用能分析提供依据。     

美卓推出新型OptiDry Twin冲击式干燥方案

在芬兰Javaskvla举行的美卓造纸机械技术交流节上，美卓公司推出了一种新型冲击式干燥方案——0ptiDry Twin。 OptiDry Twin冲击式干燥设备可在干燥初期以较高的温度提高纸幅干度．同时在完成工段保持纸幅最佳的质量和运行性能。这种设备可防止粘结．并提高纸幅强度。与其他方案相比．还能够以更高的车速运行．     

干燥部对纸页质量的影响

干燥部影响纸的多种质量特性，如光学和流变特性、卷曲和收缩性。此外，在压榨和干燥部之间，湿纸的牵引力对纸的其他特性也有着显著的影响。尽管新的烘干方法如Condebelt法和穿透干燥技术，在近些年来已经商业化，但印刷书写纸机以及纸板机仍然使用普通的烘缸干燥法。而且近２０年来干燥烘缸也没有多大的改变，所不同的是干燥条件改变了，并为质量控制创造了新的时机。近几年来，纸机速度得到了迅速的提高，纸机的运行性能变得越来越重要。在高速纸机上，这已经引起了某些质量问题。１从压榨到干燥部引纸当提高纸机速度时，为了避免降低纸…     

青州造纸厂纸袋纸纸机干燥部蒸汽冷凝水系统技术改造的探讨

青州造纸厂五十年代引进VOITH公司150t/d纸袋纸纸机干燥部蒸汽系统,经过两次重大技术改造,成功地引用先进节能装置——热压泵,充分使汽水分离器的二次蒸汽升再利用,以强化烘缸的蒸发能力,文章详细介绍了诙系统技术改造的工艺条件对比、控制原理,节能效果计算和相应的配套设施,对目前国内大型纸机的干燥部蒸汽系统向节能型技术改造,提出了探讨意见。     

食品干燥新技术的研究进展

阐述了各种干燥方法的技术特点，介绍了微波干燥、红外线辐射干燥、冲击干燥、渗透干燥、卤素干燥、流化床干燥以及冷冻干燥在国内外的研究和应用现状，以及这些技术在食品干燥加工中存在的问题和应用前景。     

谈谈小型涂布机干燥部

国内现存的数量众多的小型涂布机,除了建造投资省,操作简单以外,由于其车速慢,更适于配用草类浆抄造涂布原纸的质量现状。我厂有一台1092mm涂布机,由于原干燥部设备陈旧不能满足生产需要,我们将桥式干燥器原来的热风内部循环式改为呼吸式热风罩,提高了干燥能力,车速由原来的30m/min提高到60m/min以上,生产正常。下面谈谈在改造中的一点体会和设想。由于涂布操作的特殊性,涂料纸的干燥过程不同于在造纸机上湿纸页的干燥过程,所以应根据具体的涂布工艺和原纸、涂料的特性,确定相应的干燥温度曲线。涂料纸的干燥过程分为三个阶段:第一阶段为初始干燥阶段,即从开始干燥至涂层表面开始出现干燥点。在这一     

改善干燥部热回收增加效益

１纸机中能量的利用纸和纸板制造中的一个基本概念是创造效益。对生产厂家来说，做到这一点的主要方法是要不断控制所有费用和消减成本。成本包括各种来源，即原料、劳动力、管理费和能源。例如，生产１t新闻纸，１台纸机在传统干燥部需要消耗２５００～５５００MJ热能及１８００～２２００MJ电能。能量变化的需要取决于技术问题、生产封闭程度、纸机如何控制及设备的情况。几乎所有热能都用于干燥，这使得纸机的干燥部成为最大的能耗部位。对优质纸和涂布纸来说，由于纸页施胶和涂布需要附加烘干，热能的用量就会更高。在新闻纸的生产中…     

高速纸机干燥部油气润滑实验装置的设计

油气润滑作为一种新型节能技术,应用于高速纸机干燥部中,能够克服现有稀油润滑技术的诸多缺陷,改善高速纸机干燥部轴承的润滑效果。本文介绍了油气润滑技术和高速纸机干燥部轴承润滑的技术现状,并在模拟实际工况的基础上,设计了一个高速纸机干燥部轴承油气润滑实验装置,为验证相关理论设计参数提供技术论证,进而为优化实际工艺参数提供良好的研究手段。     

Recent progress in food processing applications of air impingement technology: A review

Air impingement method has been widely used in a variety of industrial applications, such as textile and paper drying, turbine cooling, and glass quenching, because it is an efficient technology with high heat and mass transfer rates. This technology has received increasing interest in the field of food processing over the last two decades, such as drying, baking, blanching, freezing, and thawing. In a food processing equipment using air impingement, jets of high-velocity air (with speeds of 10–50 m/s) are directed at a food product. The performance of the system is influenced by several critical elements, including jet velocity, nozzle array diameter and layout, jet distance, and boundary layer characteristics. The use of computational fluid dynamics, an emerging tool, has been shown to be valuable in the analysis of fluid flow and heat and mass transfer in jet impingement systems. The physical properties of impinging jets, such as turbulent mixing in the free jet zone, stagnation, boundary layer formation, recirculation, and their interactions with food products in terms of heat and mass transfer, have been discussed in this article. The benefits and disadvantages of air jet impingement technology in different food processing applications together with potential trends for improving impingement technology performance were identified and discussed. This review not only contributes to a better understanding of the research status of impingement technology on food processing but also triggers new research opportunities in this field in order to provide more healthy and nutritious food in a more sustainable way to the world's growing population.     

纸页干燥技术--OptiDry干燥技术

介绍了OptiDry、OptiDry Twin,OptiDry Vertical等先进干燥技术的发展、性能及特点。     

Fluid Flow and Heat Transfer in Air Jet Impingement in Food Processing

ABSTRACT: Air impingement technology is gaining popularity in food-processing operations such as baking, freezing, drying, and toasting. In this article, physical characteristics of impinging jets, such as turbulent mixing in the free jet region, stagnation, boundary-layer formation, recirculation, and their interactions with food products in terms of heat and mass transfer have been reviewed. The discussion includes experimental methods used for measurement of heat and mass transfer for single and multiple slot and circular jets. Procedures used for measurement of heat-transfer coefficient such as lumped sensor method, micro-calorimetric approach, and use of flux sensors are presented. Typical qualitative and quantitative flow-field studies using planar visualization and laser Doppler anemometry have been reviewed. Numerical modeling of air impingement systems is discussed with special consideration of problems arising in food-processing systems.     

采用热管气体射流冲击技术干燥香菇

采用热管气体射流冲击技术,通过单因素试验研究鲜香菇的干燥工艺,以香菇干燥成品的复水比、感官评价及能耗变化为试验指标,确定干燥温度、热风风速、喷嘴距物料高度的最佳工艺参数。结果表明:香菇气体射流冲击适宜干燥工艺参数为干燥温度60℃、风速40 km/h、喷嘴距物料的高度115 mm。     

Chemical and physical pretreatments of fruits and vegetables: Effects on drying characteristics and quality attributes – a comprehensive review

Pretreatment is widely used before drying of agro-products to inactivate enzymes, enhance drying process and improve quality of dried products. In current work, the influence of various pretreatments on drying characteristics and quality attributes of fruits and vegetables is summarized. They include chemical solution (hyperosmotic, alkali, sulfite and acid, etc.) and gas (sulfur dioxide, carbon dioxide and ozone) treatments, thermal blanching (hot water, steam, super heated steam impingement, ohmic and microwave heating, etc), and non-thermal process (ultrasound, freezing, pulsed electric field, and high hydrostatic pressure, etc). Chemical pretreatments effectively enhance drying kinetics, meanwhile, it causes soluble nutrients losing, trigger food safety issues by chemical residual. Conventional hot water blanching has significant effect on inactivating various undesirable enzymatic reactions, destroying microorganisms, and softening the texture, as well as facilitating drying rate. However, it induces undesirable quality of products, e.g., loss of texture, soluble nutrients, pigment and aroma. Novel blanching treatments, such as high-humidity hot air impingement blanching, microwave and ohmic heat blanching can reduce the nutrition loss and are more efficient. Non-thermal technologies can be a better alternative to thermal blanching to overcome these drawbacks, and more fundamental researches are needed for better design and scale up.     

Improving drying efficiency and product quality of Stevia rebaudiana leaves using innovative medium-and short-wave infrared drying (MSWID)

The effects of hot air impingement drying (HAID), hot air drying with temperature and humidity process control (HADTHPC), medium-and short-wave infrared drying (MSWID), shade drying (HD) and sun drying (SD) on the drying characteristics and physicochemical quality of Stevia leaves were investigated, MSWID was screened out most suitable for Stevia leaves drying. The relationships among drying time, microstructure, color and nutrients retention were analyzed. Compared with other drying methods, MSWID significantly reduced drying time by 15.38% and better preserved the nutrients (steviol glycosides and chlorogenic acids) due to the formation of a distinct microporous structure. Moreover, medium wave infrared (MIR) drying was superior to short wave infrared (SIR) in retaining steviol glycosides and color and improving drying efficiency. Brightness and greenness of dried Stevia leaves were significantly correlated with glycosides and chlorogenic acids content, respectively. MIR at 60 °C is recommended as the most suitable drying conditions due to the highest comprehensive score (0.723) considering drying time, energy consumption and quality. Overall, MSWID is a promising drying technology for realizing high-quality and efficient industrial production of Stevia leaves.     

气流冲击式滚筒干燥器的研究进展

气流冲击式滚筒干燥器是在常规式滚筒干燥器的基础上采用气体射流冲击新技术而发展出来的一种滚筒式干燥机。本文介绍了气流冲击式滚筒干燥器的广泛应用领域;同时,对比于常规式滚筒干燥器,描述了气流冲击式滚筒干燥器的结构与技术特点,并从干燥器结构设计特点的角度详细分析了气流冲击式滚筒干燥器的工作原理以及影响干燥器干燥效果的主要因素。     

纸张干燥技术及其能效分析(上)

纸机的干燥部是造纸厂热能消耗的最主要部分,也是节能减排工作的重点,不同的干燥方式,能源的利用效率各不相同,能源成本也存在较大差异。本文介绍了蒸汽烘缸干燥及气罩系统以及常用于涂布纸的红外干燥、热风干燥的基本原理、能源利用效率及使用成本等,并定量计算进行了说明。从辐射的原理入手,详细解释电红外与燃气红外的异同,澄清人们对这两种红外干燥器能源利用效率的误解,文中的计算结果也为干燥系统的选用或优化提供了数据支持。     

IMPINGEMENT DRYING OF POTATO CHIPS

The effect of superheated steam temperature (115, 130, and 145C) and convective heat transfer coefficient (100 and 160 W/m²C) on the drying rate and product quality attributes (shrinkage, density, porosity, color, texture, and nutrition loss) of potato chips was investigated. Furthermore, potato chips dried by impinging superheated steam (130 and 145C, h = 100 W/m²C) were compared to air dried (same conditions), commercial, and fried potato chips. Temperature and convective heat transfer coefficient had a significant effect on the drying rate during superheated steam impingement drying. Potato chips dried at higher drying temperature and convective heat transfer coefficient showed less shrinkage, lower bulk density, higher porosity, and darker color when compared to chips dried at lower temperatures and convective heat transfer coefficients. They were also less hard and had a lower vitamin C content. A higher rate of evaporation during the falling rate period was obtained when superheated steam drying was compared to air impingement drying. Potato chips produced using superheated steam impingement drying showed more shrinkage, higher bulk density, lower porosity, and lighter color than chips dried with air under the same temperature and with the same convective heat transfer coefficient (130, and 145C, h = 100 W/m²C). Moreover, superheated steam‐dried potato chips retained more vitamin C during the drying process.