大型粮食真空干燥设备的研究开发及应用

介绍了真空低温连续干燥新技术的发展背景，通过技术性分析，探索出了一条解决粮食干燥问题的新途径。加强新一代真空低温连续干燥新技术的推广和应用具有重要的现实意义，必将提高能源利用效率，起到节能减排的作用，为我国绿色干燥技术的发展指明了方向。     

微波真空组合干燥技术的研究

微波真空干燥是综合微波干燥和真空干燥各自优点的一项新技术,将微波干燥的快速高效性和真空干燥的低温高质相结合,在真空条件下利用微波对物料进行干燥处理,从而实现物料的快速低温干燥。着重阐述了微波真空组合干燥技术的机理、特点、干燥动力学以及影响微波真空干燥的重要因素,并对微波真空组合干燥的应用研究进行了介绍。     

低温热泵干燥装置的技术方案分析

低温热泵干燥装置在化学品、食品、药品、农副产品的干燥中具有广泛需要。给出了基本型、真空型和吸附剂型三类低温热泵干燥装置,对其结构、工作原理和特性进行了简要分析。分析表明,在初投资方面,基本型最低,真空型最高;在能源效率方面,真空型最高,基本型最低;吸附剂型在初投资和能源效率方面均居中。上述工作可为低温热泵干燥装置的设计提供较好的参考。     

真空干燥设计方案的模糊综合评价

构建了真空干燥模糊综合评价指标体系，运用综合评价法和模糊数学的相关理论建立了模糊综合评价模型，通过对300t／d玉米真空低温连续干燥具体案例的评价，为真空干燥在设计过程中选择最佳的方案提供了理论依据。     

高水分玉米真空低温干燥工艺生产性试验研究

东北是我国玉米的主产区，产量占全国的30％～40％。受自然条件的影响，玉米收获水分常达22％～30％；成熟度及含水率都不均匀。根据玉米热敏性物料干燥的热特性及市场要求，考虑到它的热稳定性及破碎敏感性的特点，采用真空低温干燥技术进行了生产性试验，设计了300t／d高水分玉米真空低温连续干燥工业自动化生产线，对生产性试验关键技术进行了分析和研究。依据试验结果，分析玉米含水率、干燥介质温度、真空度、玉米温度、干燥时间、汽化蒸发温度等参数之间的联系与相互作用。生产试验表明：玉米含水率在24％时，维持干燥塔内真空度，采用高温水加热，汽化蒸发温度40～43℃，一次降水幅度达到10％～15％，保证了玉米品质的色、香、味、形及营养成分，具有干燥品质好、降水速度快、产量高、能耗低、操作方便、经济性价比高等优点。     

黑加仑真空冷冻与微波真空联合干燥工艺研究

以黑加仑为原料,对其进行了真空冷冻与微波真空联合干燥工艺的研究。结果表明：先真空冷冻后微波真空干燥（FDMV）的组合方式是可行的;联合干燥合理工艺参数为：微波功率1．34kW。绝对压力11kPa,转换含水率为20％（wb）;通过试验验证,联合干燥生产的脱水黑加仑的感官品质和营养成分接近真空冷冻干燥,联合干燥方式对节省干燥时间和降低能耗是有效的。     

真空连续干燥系统抽气量的计算

介绍了真空连续干燥装置真空系统—抽气量的计算方法,通过与实际实验装置操作情况的比较,验证了该计算方法的可行性。     

粮食干燥技术评价指标体系的构建

通过运用模糊综合评价法、层次分析法对粮食干燥技术构建评价指标体系,提出运用多级模糊综合评价方法以及全面的定量化和定性化的层次结构评价模式,通过300t/d玉米真空低温连续干燥实际案例进行综合评价,建立了塔型连续真空干燥设计方案的模糊综合评价、粮食干燥企业工艺优选模糊综合评价、粮食干燥品质质量AHP综合评价和粮食干燥整体效益AHP综合评价,结果表明四种综合评判体系的构建是可行的。     

WDZ型智能化微波真空连续干燥机

该干燥机在采用微波和真空技术的同时,还运用了动态结构和干燥过程动态显示手段,物料在干燥器内作直线连续运动,在微波场中和真空环境下完成干燥的全过程。在干燥过程中,物料接收到的微波总能基本一致,物料的干燥程度也基本相同,物料干燥均匀,并实现了连续干燥作业,从而大大克服了间歇干燥产量低、操作不便等弊病。该设备由于还同时采用了真空干燥技术,其汽化温度大大降低,物料中的湿分能迅速变成蒸汽,从而使物料在低温下就能进行干燥,特别适用于低融点、热敏性物料的干燥。将其应用于黏稠、胶状、极难干燥的浸膏类物料场合,取得了非常满意的效果。     

连续性真空低温玉米烘干塔的研发及性能分析

为了解决粮食的晾晒问题,远弘真空干燥对真空干燥设备进行了资源整合,研发了性能更好,更加高效的连续性真空低温玉米烘干塔,并对其系统组成、烘干流程、技术参数和经济性进行了介绍和分析。     

微波干燥卫生陶瓷的研究与设备开发

本文利用微波干燥法进行卫生陶瓷坯体干燥试验,探究微波可以实现对卫生陶瓷快速干燥的原因。在此基础上,对围绕着微波设备大型化、连续化中面临的关键技术及微波干燥电耗相对较高等技术进行攻关,开发了卫生陶瓷微波干燥辊道窑,并在实际工厂使用。结果表明:微波干燥过程实现了沿坯体纵向与沿坯体局部区域横向的均匀干燥及微波干燥能显著提高干燥的内扩散速率,最终实现对卫生陶瓷的快速干燥;采用微波、热风耦合加热技术能显著降低微波干燥电耗;开发的卫生陶瓷微波干燥辊道窑,可极大缩短干燥周期,降低场地占地面积,提高干燥合格率。     

污泥低温真空脱水干化成套技术的设计探讨

随着我国经济技术不断发展,污泥处置将从传统的卫生填埋向污泥干化焚烧或资源化利用方向发展。低温真空脱水干化成套设备采用低温真空干化原理,可以一次性将污泥的含水率从98%左右脱水干化至30%~40%,为后续的焚烧或资源化利用创造了条件。池州市前江工业园污水处理厂通过引进该项技术,实现了在一套设备内干化污泥的目的,出泥含水率小于40%。     

Study of Intermittent Low-Pressure Superheated Steam and Vacuum Drying of a Heat-Sensitive Material

Low-pressure superheated steam drying (LPSSD) has recently been applied to drying of various heat-sensitive foods and bioproducts with success. Several studies have shown that the quality of LPSSD-dried products is superior to that obtained using conventional hot air or vacuum drying. However, drying time and energy consumption for LPSSD is generally greater than that for vacuum drying. Therefore, it is necessary to examine different methodologies to improve the energy efficiency of LPSSD. An intermittent drying scheme is one possible method to reduce the energy consumption of the process while maintaining the desired product quality. In this study, the effect of intermittent supply of energy (through an electric heater and steam injection to the dryer) and vacuum (through the use of a vacuum pump) at various intermittency values or on:off periods (10:5, 10:10 and 10:20 min in the case of intermittent supply of energy and 5:0, 5:5, and 5:10 min in the case of intermittent supply of vacuum) at the on-period setting temperatures of 70, 80, and 90°C on the drying kinetics and heat transfer behavior of the drying samples (banana chips) was studied. The effects of these intermittent drying schemes and conditions on the quality parameters of dried banana chips; i.e., color, shrinkage, texture, and ascorbic acid retention, were also studied. Finally, the energy consumption values for intermittent LPSSD and vacuum drying were monitored through the effective (or net) drying time at various intermittent drying conditions and compared with those using continuous LPSSD and vacuum drying.     

A New Drying Approach to Enhance Quality of Konjac Glucomannan Extracted from Amorphophallus muelleri

A new drying approach to enhance physical quality of konjac glucomannan extracted from Amorphophallus muelleri was studied. It consisted of a comparison between microwave vacuum drying and conventional hot-air drying. The effects of microwave vacuum drying and hot-air drying on drying kinetics and physical and structural properties such as color, bulk density, particle density, porosity, viscosity, and morphology of konjac glucomannan (KGM) flour were investigated. It can be concluded that microwave vacuum drying significantly reduced drying time and increased porosity of dehydrated products which have a positive effect on the viscosity of the KGM solution. In contrast, it decreased bulk density and particle density when compared with conventional hot-air drying. Microstructure observations revealed the presence of large cavities in the granules of microwave-vacuum-dried KGM samples. However, there was a slight change in color of the microwave-vacuum-dried samples, resulting in a lower whiteness index than the whiteness index of hot-air-dried samples. Hence, microwave vacuum drying was found to have a number of advantages over the conventional hot-air drying method. Therefore, microwave vacuum drying has potential to become a useful drying method for the industrial production of KGM flour.     

我国木材干燥技术与研究动态

阐述了我国木材干燥技术应用状况及面临的问题,介绍了我国木材干燥学术活动的情况和理论研究动态。指出以蒸汽为热源的常规干燥仍将占木材干燥的主导地位,约在80％以上;真空干燥、热泵除湿干燥、微波与高频干燥、高温干燥、加压干燥等其它干燥方法都在各自适用的范围内有一定的发展。木材的渗透性、木材干燥过程的水分迁移机理等有关木材干燥的传热传质方面的基础理论研究正在加强;高效节能的木材干燥技术是目前研究的重点课题。我国木材干燥技术正由经验型转向以干燥理论为基础的科学型方向发展。     

A Novel Atmospheric Freeze-Drying System Using a Vibro-Fluidized Bed with Adsorbent

Atmospheric freeze drying (AFD) in a vibro-fluidized bed dryer coupled with an adsorbent and multimode heat input is proposed for dehydration of food products at lower cost than the traditional freeze-drying process under vacuum. The aim of this project is to study the proposed AFD system using a vortex tube to produce low-temperature dry air, an alternative for producing dried food products of high quality. An experimental setup was designed and built to permit simultaneous application of convection, conduction, and radiation heat input to the drying material above its freezing point to ensure sublimation. A parametric evaluation over a broad range of possible parameter values was carried out using cubic-shaped potato and carrot as model heat-sensitive products. The influence of various system parameters on drying kinetics, quality, and functional properties of the dried products (color, rehydration properties, and morphology) were investigated. Comparison between physical quality and drying characteristics of the AFD system with AFD using fixed bed, fluidized bed dryer, and also with traditional vacuum freeze drying were carried out to investigate the viability of this new system. Results indicate that proposed system is an alternative to reduce the process time as well as to maintain the product quality at lower cost.     

A Novel Atmospheric Freeze-Drying System Using a Vibro-Fluidized Bed with Adsorbent

Atmospheric freeze drying (AFD) in a vibro-fluidized bed dryer coupled with an adsorbent and multimode heat input is proposed for dehydration of food products at lower cost than the traditional freeze-drying process under vacuum. The aim of this project is to study the proposed AFD system using a vortex tube to produce low-temperature dry air, an alternative for producing dried food products of high quality. An experimental setup was designed and built to permit simultaneous application of convection, conduction, and radiation heat input to the drying material above its freezing point to ensure sublimation. A parametric evaluation over a broad range of possible parameter values was carried out using cubic-shaped potato and carrot as model heat-sensitive products. The influence of various system parameters on drying kinetics, quality, and functional properties of the dried products (color, rehydration properties, and morphology) were investigated. Comparison between physical quality and drying characteristics of the AFD system with AFD using fixed bed, fluidized bed dryer, and also with traditional vacuum freeze drying were carried out to investigate the viability of this new system. Results indicate that proposed system is an alternative to reduce the process time as well as to maintain the product quality at lower cost.