干燥后玉米水分不均匀度影响因素的分析与建议

本文根据对顺流式、顺逆流式、混流式、横流式、双塔玉米干燥机及小型玉米干燥机进行全面技术性能测试结果，分析影响玉米干燥后水分不均匀度高的因素。通过对工艺结构的研究分析和实际测试结果的线性分析，认为玉米干燥机工艺结构、穿越粮层风速和粮层厚度是影响干燥后玉米水分不均匀度的主要因素，并针对已有玉米干燥机及新建玉米干燥机，分别提出解决问题的方法。     

影响干燥后玉米水分不均匀度工艺参数的分析

粮食仓储业中，干燥后玉米水分不均匀度的高低，对玉米长期储存保管有直接影响。通过玉米干燥机实际测试结果，研究分析各工艺参数对水分不均匀度的影响，探讨影响水分不均匀度的主要因素。     

连续横流稻谷干燥机干燥及缓苏试验探究

针对我国东北地区稻谷收获季节干燥机的市场需求,结合连续横流式干燥机干燥稻谷的生产过程,分析了横流式烘干机内部热风与谷物温度分布情况、烘干过程对稻谷水分不均匀度以及缓苏对稻谷爆腰及水分不均匀度的影响。结果表明:设计合理的横流式干燥机不会因为自身结构原因造成干燥去水不均匀;干燥过程中的热风道内热风温度不均匀性小于1~2℃;15h的缓苏时间可以有效降低稻谷碎米率,并是平衡干燥后稻谷水分较经济的时间。     

混流式水稻干燥设备试验示范应用

混流式粮食干燥机是目前国内外粮食烘干行业的主流机型,具有干燥强度大、一次性降水幅度大及综合性能好的优点。 针对目前我国南方水稻以机械收获为主,收获后水稻水分高、含杂率高,易造成干燥速度慢、干燥不均匀的问题,在我国湖南水稻产区建成了适用于水稻的混流式水稻干燥机,并开展了水稻干燥的示范和应用。     

容重法在线检测玉米水分的研究

容重是评价粮食质量的一项重要指标,本文首先分析了几种主要粮食作物容重与水分的相关关系,进而确立了通过容重预测玉米水分的主题。然后在自制的干燥试验台上,模拟干燥机的干燥方式获得如下实验数据：几种风速下不同风温时玉米容重与水分的关系曲线,以及几种风温下不同风速时玉米容重与水分的关系曲线,然后对得到的不同干燥条件下的试验数据利用Design-expert8.0.5软件进行处理与分析,并采用Matlab对大量实验数据进行拟合,得到了玉米含水率(M)和干燥过程热风温度(T)两个因素与玉米容重(ρ)之间相互关系的较为合理的数学模型,并自主设计了容重法在线检测玉米水分的实验装置,最后将该装置安装在粮食干燥机的出口处进行了性能试验,并进行误差分析。说明通过粮食容重预测水分是可行的,为粮食水分在线检测提供了又一种新方法。     

我国油菜籽干燥技术的现状及发展趋势

我国是世界最大的油菜籽生产和消费国,近年来油菜种植面积和产量还在不断增长.但我国油菜籽干燥机的应用还不普遍,一些实际使用的干燥技术还相当落后.分析了仓式固定床干燥机、滚筒式干燥机、流化床式干燥机、混流式粮食干燥机以及微波干燥等典型油菜籽干燥机存在的优点与不足,并对今后发展油菜籽干燥机提出了一些有益的建议.     

CTHL系列混流式粮食(种子)干燥机

CTHL系列混流式粮食(种子)干燥机是由北京西达农业工程科技集团自行研制开发的新一代粮食设备.其先进的干燥工艺、精美的外型和优越的性能深得用户喜爱.该机可广泛用于对玉米、水稻、小麦、高粱、油菜籽及大豆等不同作物的烘干. 该机特点: ①技术参数采用计算机优化模拟确定,干燥强度大、热效率高,干燥后的粮食品质好,可一机多用.②积木式的结构,便于吊装、运输和维修.③可实时调节的无级变速排粮机构,将成品粮的水分不均匀度降至最低.④风温自动控制系统,使用户可以在50～110℃的范围内自由设定热风温度.⑤以高效间接加热热风炉为热源,对粮食无污染,可根据用户要求,选用燃煤、燃油或者燃气作为燃料.     

低温循环式粮食干燥机降水能力生产性试验

以低温循环式粮食干燥机的实际数据为基础,对干燥机干燥时间、单位时间脱水量、水分检测值等进行了探究。结果表明,低温循环式粮食干燥机的干燥时间与粮食水分成正相关关系;单位时间脱水量为不定值,并呈逐渐降低的趋势;且第1次烘干后,实际水分值与设定值之差在1.3%以内。     

干燥过程中玉米水分质量分数均匀度的高光谱图像无损检测

水分含量均匀度是干燥过程一个重要指标,它是评价干燥食品质量和干燥工艺一个重要参数。作者以干燥过程中的玉米为研究对象,研究高光谱图像技术检测水分质量分数均匀度的方法。采用均值特征和标准差特征结合偏最小二乘法(PLS)建立预测模型;并用正交信号校正法对均值特征和标准差进行预处理。结果表明:均值特征和标准差进行预处理后所建立的模型效果较好,预测相关系数为0.839,预测均方根误差为1.74%,潜在变量的数目为2个。研究表明:高光谱图像技术可用于水分质量分数均匀度的直接无损检测。     

玉米在转筒干燥器中的干燥工艺优化研究

玉米收获时通常都处于较高水分状态,含水量高,影响玉米的发芽率,导致霉变,需要将其干燥到安全水分以下才能进行储藏。为了更好地储藏玉米,本文利用转筒干燥工艺对玉米进行干燥处理,研究了入口风温、转筒转速、转筒倾角及滞留时间等4个因素对干燥效果的影响。并通过二次回归通用旋转组合设计,研究了干燥工艺对加工后玉米的含水率的影响,得出了以上4个因素对干燥效果的回归方程,分析了各个因素单独作用时的影响及它们之间的交互作用。     

DYNAMIC PROGRAMMING FOR PROCESS OPTIMIZATION 1. AN ALGORITHM FOR DESIGN OF MULTI-STAGE GRAIN DRYERS

A dynamic programming algorithm for determining the optimum operational parameters and size of a multi-stage concurrent flow dryer with intermediate tempering stages was developed. The objective function was based on energy and capital costs. The operational parameters were constrained by the desired final moisture content and the maximum allowable value of important grain quality factors. The two- and three-stage concurrent flow dryers have a higher investment cost than the single stage unit, but were less expensive to operate due to the decreased grainflow rate in the single-stage unit. On the basis of operating cost, the multi-stage concurrent flow dryer was preferable to a comparable crossflow dryer for drying corn.     

Characterization of in situ dry matter and nitrogen digestion of various corn grain forms

Corn was harvested and stored as either dried shelled, dried ear, high moisture shelled, or high moisture ear. Shelled corns were rolled and ear corns were ground through a forage harvester. High moisture corns were stored in sealed drums. Each corn type was subjected to in situ ruminal digestion with incubation times through 100 h for both original forms and ground at 5 mm. Dry matter, N, and nonprotein DM digestion rates were determined. Unground dried shelled corn possessed the fastest and high moisture ear corn the slowest rate of DM digestion; however, extent of digestion was greatest for high moisture corns within 16 h of ruminal exposure. Grinding increased the rate of shelled corn digestion. Nitrogen digestion rate was fastest for high moisture ear corn and slowest for dried shelled corn. Grinding increased the rate of nitrogen digestion for all corn forms except high moisture shelled corn. Generally, correction for bacterial nitrogen contamination resulted in increased rate of nitrogen digestion. Dried shelled corn possessed the fastest rate of nonprotein DM digestion. Ratio of nitrogen to nonprotein DM rates ranged from .56 to 1.24 for dried shelled corn and high moisture ear corn, respectively. Grinding narrowed this range. Digestion rates of corn forms may not necessarily reflect initial (1 to 16 h) extent of ruminal nutrient availability.     

Effects of propionic acid added to supplemental corn on utilization of complete ensiled diets by lactating dairy cows

Two bottom unloading silos were filled with alternate loads of alfalfa (Medicago sativa L.) and ground shelled corn grain mix (1:5, grain:forage, wet basis) to determine effects of propionic acid added to supplemental corn on performance of lactating dairy cow consuming a complete ensiled diet. One silo received grain mix containing 1% propionic acid. Each of two groups of six lactating cows was fed one of the complete ensiled diets supplemented with high moisture corn, dried-shelled corn, or no supplemental corn for 4 mo. Cows that consumed the acid-treated diet produced less milk, fat, and protein than cows consuming the untreated diet. Supplemental high moisture corn and dried shelled corn increased milk and protein yields, and high moisture corn increased fat yields compared to the unsupplemented. Daily variation of the ratio of grain:forage indicated that alternate load additions of forage and grain resulted in poor mixing of ration components and may be related to some of the differences in performance.     

Sequential modeling of fluidized bed paddy dryer

A sequential method was developed to model a continuous plug flow fluidized bed dryer. The method is based on dividing the dryer into sections in series with ideal mixing for both solid and gas phases in each section. In order to determine the proper number of sections, drying experiments were carried out using paddy at different operating conditions. It was shown that the number of sections can be correlated to Damköhler number, which includes kinetic and hydrodynamic parameters of the process. The model is able to predict the particle’s moisture profile along the bed as well as the moisture content of dried product. It was shown that the model fits the experimental data satisfactorily with the correlation coefficient of 0.989. Moreover, the model was tested against available data in the literature at different scales and operating conditions for which an error of less than 4.5% was observed in predicting the paddy moisture content at the outlet.     

Stability of zearalenone during extrusion of corn grits

The effects of extrusion cooking on the stability of zearalenone (ZEN) in spiked (4.4 microg/g) food-grade corn grits were investigated using a twin screw extruder. A ground rice culture material containing a high level of ZEN was used to spike the corn grits. The extrusion variables were screw type (mixing and nonmixing), temperature (120, 140, and 160 degrees C), and moisture content (18, 22, and 26%). Both unextruded and extruded samples were analyzed for ZEN by high-performance liquid chromatography. Extrusion cooking of the corn grits resulted in significant reductions of ZEN in grits extruded with either mixing screws or nonmixing screws, but use of mixing screws was somewhat more effective (66 to 83%) overall than nonmixing screws (65 to 77%). Greater reduction of ZEN was observed at either 120 or 140 degrees C than at 160 degrees C. The moisture content of corn grits was not a significant factor affecting reduction of ZEN during extrusion with either mixing or nonmixing screws.     

改性甜玉米浆喷雾干燥条件的探讨

对酶法改性甜玉米浆,经喷雾干燥制备玉米粉进行了探讨。试验以水分含量及感官为指标确定了最佳喷雾干燥参数。实验结果表明:在进口温度160℃,热风流量0.55m3/h、物料流量650mL/h条件下,改性甜玉米粉水分含量低,颜色淡黄,滋气味较佳。同时经过改性的甜玉米水溶性及人体消化性提高,可制成颜色淡黄、风味较佳的甜玉米饮料、汤料及具有广阔应用空间的甜玉米原料粉等。     

组挂式粮食干燥仓玉米籽粒自然干燥研究

新收获高水分玉米得不到及时干燥处理会引发严重霉变问题,影响农民增产增收。通过自然晾晒翻倒干燥、环境及粮堆内温湿度检测、水分检测、真菌孢子检测等技术方法,对目前研发的大农户晾粮干燥和安全储粮的新仓型——组挂式粮食干燥仓进行分析和评价,为组挂式粮食干燥仓推广应用提供理论依据。     

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。     

Comparison of performances of pulsed and conventional fluidised-bed dryers

Consumption of energy, outlet moisture content and quality of the dried commodity are important parameters of paddy-dryer performance. The fluidised-bed paddy-dryer has been commercialised for several years and in this paper, paddy drying by pulsed and conventional fluidised-bed dryers are compared. Experimental results have shown that the variation of moisture content at the exits of both dryer types in test runs was very small. Heat utilisation was more effective when such dryers were used to dry paddy at moisture contents above 24% dry basis and up to 50% of the thermal energy was saved by recycling 70–80% of the air. Paddy qualities i.e. head-rice yield and colour of the dried white rice were similar with both dryers and almost the same as the original undried values, or slightly higher in the case of head-rice yield, depending upon the drying conditions. Below 28% dry basis, it is recommended that inlet-air temperature should be lower than 145 °C in order to maintain white colour. The cooked rice obtained from paddy dried at a temperature of 145 °C was harder than naturally dried control samples. A mathematical model based on energy and mass balance predicted values in good agreement with experimental results for both the pulsed and conventional fluidised-bed dryers. Calculated thermal and electrical energy consumptions indicated that the pulsed flow dryer was more economical than the conventional dryer.