低温循环式烘干机对南方高水分稻谷干燥的实践

中国南方湿稻谷含水率往往高达24％～35％,如果干燥不及时则会造成霉变或发芽等损失,如果干燥不当则易产生爆腰而造成碾米时的碎米率增大.谷粒的特殊结构使稻谷成为一种较难干燥的谷物.文章介绍了一种配有电脑自动水份测定仪的低温循环式烘干机这种低温循环烘干机对湿稻谷的平均干燥速率为0.8％～0.9％/h,每吨湿稻谷的烘干成本为50元左右,收购稻农的湿谷进行集中烘干可以获取30元/t的利润;与场地晾晒稻谷相比,集中烘干稻谷可以获取442元/t的经济效益.     

Effectiveness of the solar biomass hybrid dryer for drying and disinfestation of maize

The Solar Biomass Hybrid Dryer (SBHD) is a new technology developed in Ghana for grain drying and utilizes biomass (agro-residues, timber scraps, etc.) along with solar drying, and is especially useful for drying during rainy periods of the year when solar drying cannot be relied on. This study assessed the effectiveness of a 5.0-MT SBHD comprising a solar tent and a furnace for thermal drying and disinfestation of maize. Mortalities of adults of Sitophilus zeamais (Motschulsky), Tribolium castaneum (Herbst) and Cryptolestes ferrugineus Stephens were assessed. Additionally, mortalities of immatures of these three species were assessed. Internal and cage temperatures (°C) in the SBHD, sun drying (SD) and laboratory (control) were monitored, as were moisture content (MC) and thermally (stress) damaged kernels (TDK) (%). During the 7-h experiment, mean internal temperatures in the SBHD, SD and laboratory were 52.3 ± 1.0 °C, 41.4 ± 0.8 °C and 30.3 ± 0.2 °C, respectively. Similarly, temperatures in cages in the SBHD (49.5 ± 1.0 °C) were higher than those for cages in the laboratory (29.9 ± 0.2 °C) and SD (38.2 ± 0.6 °C). Reduction in the moisture content of maize dried using SBHD, SD and under laboratory conditions were 7.7, 5.2 and 2.9%, respectively. This corresponded to grain MC reduction rates of 1.1%, 0.74% and 0.4% per hour. There was 100% mortality of S. zeamais and C. ferrugineus adults achieved in only the SBHD; some immatures of all three species survived in all three treatments. However, survival of immatures was highest in the laboratory, followed by SD and lowest in the SBHD for all three species. Percent TDK was higher in the SBHD (6.7 ± 0.9) than SD (3.3 ± 0.3) and laboratory (2.7 ± 0.3). These data show that the SBHD is effective for both drying and disinfestation of grain.     

Drying of red pepper slices in a solar greenhouse dryer and under open sun: Experimental and mathematical investigations

The present work is mainly focused on the study of the solar drying of red pepper grown in the North of Tunisia. A new mixed mode solar greenhouse dryer (SGD) with forced convection was used in the drying experiments. To further understand the characteristics of the SGD, an open sun drying experiment was conducted under the same climatic condition. The results show that the constant rate period is absent from the experimental drying curves. The experimental drying curves show only the falling rate period. Thus, the drying time which was three days in the open sun decreased to two days in the SGD. The drying data were fitted to eight different mathematical models. The fit quality of the proposed models was evaluated by using the coefficient determination (R²), reduced chi-square (χ²) and root means square error (RMSE). Among the models, Modified Henderson and Pabis model for the forced solar drying and the open sun drying was found to best explain the thin-layer drying behaviour of pepper slices. The instantaneous thermal efficiency of the solar collector varied between 30% and 80%, at a mass flow rate of 0.047 kg/s. The overall energy efficiency of the solar dryer was 34%. Finally an economic evaluation was calculated using the criterion of payback period which was found very small 1.02 years compared to the life of the dryer (SGD) 20 years.     

粮食干燥机QFD建模方法研究

对质量功能配置设计理论进行分析介绍,在此基础上,建立了干燥机一级质量屋模型,并对干燥机进行了综合竞争能力分析。     

粮食烘干机温度控制系统的设计

设计一套粮食烘干机温度控制系统,以粮食烘干机水分测量系统为前置,用于谷物类粮食烘干过程中的变温控制.温度控制核心为STM32F103C8T6单片机,依靠步进电机驱动单元对可控硅调压器完成功率控制.绘制出PCB(Printed Circuit Board)板的布局布线,完成控制系统制作并进行联调测试.基于粮食烘干机水分测...     

新型太阳能干燥装置在枸杞烘干中的应用

本文简要地介绍一种新型太阳能枸杞干燥装置结构形式。通过太阳能热利用原理计算推导出在太阳能集热器上的辐射强度,根据经验公式算出所需的集热器有效面积,通过实测得出每千斤枸杞所配置最佳面积。     

烘干机内部谷物水分实时检测系统

目的:减少贮存时因水分含量高引起的谷物霉变.方法:通过在多地进行数据测量确定含水量与检测频率的函数模型,设计一套以STM32单片机为控制芯片的烘干机内部谷物水分实时监测系统.设计平行极板传感器来检测不同含水量谷物的电容变化值,经由硬件电路将电容值转换为频率值,经过单片机计算后可得到烘干机内部谷物实时水分含量,再利用RS485通讯协议传输至显示屏实时显示.结果:该系统在线监测误差在0.5%以内,上位机实时显示水分含量的延迟时间小于0.1s,完全满足工程应用要求.结论:通过实地安装测试,该系统工作效率高,不会对谷物造成二次伤害.     

Drying kinetics of rough rice grain

It is shown that thin layer drying of rewetted rough rice grain in air flow may be interpreted in terms of Fick's law solution for diffusion from a sphere. Diffusion coefficients were calculated by non-linear regression analysis comparing actual and predicted values of grain moisture content. The activation energy of rough rice was calculated assuming an Arrhenius type equation for moisture diffusivity dependence on the inverse of the absolute temperature.     

HXHT1小型粮食干燥机的简介与试验

简述了所研发的HXHT1型小型粮食干燥机的结构特点和工艺流程,设备采用逆顺流加热及缓苏的干燥工艺,并配备小型生物质燃料热源,具有热效率高、节能显著、烘干品质好、成本低、可操作性强、通用性及适用性好的优点。产品具有广阔的市场前景。     

对粮食烘干机烘干工艺的分析与探讨

介绍辽宁省内国储库中粮食烘干机的使用现状，分析粮食烘干塔中存在的问题。     

新型粮油烘干机的研究和开发

为改善我国粮油物料机械化烘干过程中存在的热效率不高、热风温度波动大及污染环境等问题,研发了新型粮油烘干机,对新型粮油烘干机的工艺参数、结构、高效供热装置、多重环保装置、过程监测控制等方面开展的集成化设计和创新型应用工作进行了阐述。新型粮油烘干机采用负压吸入式进风形式,工艺参数上设置不同的烘干缓苏时间比,热风风量较以往设计提高20%,控制表观风速在0.20~0.25 m/s,实时监测料温以控制受热温度和时间;结构上采用全镀锌装配式结构,多段烘干和缓苏相结合工艺,变截面角状上下交错布置形式,分层进风梯度冷却方式,变频电机驱动可调节排料机构,多点进料、多点出料方式;同时采用天然气线性燃烧技术和燃烧装置供热,重力沉降和离心除尘相结合对烘干废气进行处理及多个温度传感器进行干燥过程的监测控制。实际应用表明,新型粮油烘干机具有高效、节能、低碳、清洁的特点,符合我国现代农业高质量发展的实际需求。     

我国小型粮食干燥机的现状与发展前景

介绍了我国小型粮食干燥机的现状,分析了存在的问题并提出了在政策、技术方面可采取的对策,展望了小型干燥机的发展前景.     

连续和批次循环小型粮食烘干机的研发

针对目前国内使用的小型批次循环式粮食烘干机在工艺和使用功能上存在的不足,介绍了一种可以连续和批次循环的小型粮食烘干机,并对其系统组成、结构和工作原理进行了叙述。通过对烘干机主要技术参数的设计计算,确定了合理的工艺参数和结构参数。与现有的批次循环式粮食烘干机相比,该机具备连续式和批次循环式的两种烘干模式,烘干缓苏比可调节,可根据需要启用烘后物料的冷却功能,并在结构设计上采用多项专利技术。该样机经生产验证和国家级粮食干燥设备检测机构检测,各项技术指标均达到和超过了国家及行业标准的要求,使用操作方便,真正实现了一机多能、一机多用。     

粮食干燥机废气回收工艺技术研究与实践

根据植物性杂质与粉尘等废气的特性,结合粮食干燥机的特点,采用全封闭结构、负压粉尘杂质集中分离回收工艺,改变露天开放式的干燥作业方式,实现植物性杂质和粉尘的有序排放。经过生产验证,植物性杂质和粉尘回收率可达90%,能耗降低3%以上,既解决了废气排放超标等环境污染问题,还能将回收的废料加工成为生物质颗粒变废为宝,同时减少干燥机热量散失,提高干燥热效率。     

Computerised control system for an experimental solar lumber dryer

The microcomputer based control system employed in an experimental highly efficient solar kiln and the advantages of using this approach in solar wood drying are discussed. The control system consisting mainly of a personal computer and a data acquisition unit, performs a number of measuring and control functions. The monitored drying variables are wood M.C., collector's temperature, kiln's temperature, and R.H. The M.C. is monitored by recording the weight of the 3.2 m³ timber stack, resting on a weighbridge. The direct and continuous monitoring of timber moisture and equilibrium moisture employed by the control system, makes it possible to run the solar drying process to a target value formed from these two measured drying variables (drying gradient). The developed control system is compared with a semiautomatic system controlling the same solar klin.     

试验型太阳能锯材干燥窑的计算机控制系统

本文讨论试验型高效太阳能干燥窑采用微机控制系统和探讨利用太阳能干燥的优点.控制系统主要包括个人计算机和一个数据采集装置,执行大量的测量和控制功能.监测的干燥变量有木材含水率、收集器温度、干燥窑温度和相对湿度.记录放在地磅上3.2m3的木材堆垛的重量以监测含水率.木材湿度和平衡温度的连续监测采用控制系统,使它在太阳能干燥运转过程中达到两个测量干燥变量(干燥梯度)的目标值.开发该控制系统与相似的太阳能干燥窑的半自动系统控制相比较.