直管气流干燥模拟及分离过程的优化设计

对已建立的直管气流干燥模拟方程采用标准四阶龙格库塔法进行了计算机数值求解． 对于多自变量参数干燥、分离系统的优化方程,依旧以模拟方程为基础,采用多次正交试验法进行模拟试验并求出相应的目标函数,逐渐逼近最优值,最终获得了最优值,并对结果进行了分析．     

直管气流干燥模拟及分离过程的优化设计

对已建立的直管气流干燥模拟方程采用标准四阶龙格库塔进行了计算机数值求解。对于多自变量参数干燥、分离系统的优化方程,依旧以模拟方程为基础,采用多次正交试验法进行模拟试验并求出相应的目标函数,逐渐逼近最优值,最终获得了最优值,并对结果进行了分析。     

云南核桃(Juglans sigillata Dode)对流干燥传质模拟（英文）

在菲克定律与质量守恒定律的基础上建立了模拟云南核桃干燥过程的一维非稳态传质数学模型.通过边界条件的处理,结合云南核桃热风干燥试验,对其干燥过程中内部各层水分分布进行了模拟预测.将含水率的预测值与试验值对比可知该模型与试验数据吻合得很好,试验条件下云南核桃的有效水分扩散系数变化范围为1.14×10-9~1.73×10-9m2/s.干燥初期云南核桃表层的含水率下降速度比内层快得多,之后内层含水率下降速度比表层要快,最终各层含水率稳步下降;从表层到中心,湿度梯度随着干燥时间的增加逐渐减小.分析表明在核桃的干燥过程中,外壳是影响水分扩散的主要阻力之一.该模型有助于云南核桃干燥过程传热传质耦合的研究以及复杂模型的建立.     

干湿交替下混凝土氯离子运输模拟

在氯盐环境中,干湿交替区域是混凝土结构耐久性设计最为关键的区域.考虑水分在干燥和湿润情况下传输速度的差异,对干燥和湿润过程采用不同的扩散系数,建立了干湿交替下混凝土内水分传输的模型.并在此基础上建立了干湿交替情况下氯离子扩散和对流传输模型,并将上述模型在空间域和时间域离散,采用有限元方法求解.将数值模拟结果与解析解和试验结果进行对比,吻合的较好,验证了数值模型的准确性和可靠性.     

振动流化床干燥分区供热方式研究

基于由小试结果回归得到的煤炭振动流化床干燥动力学数学模型及传热方程、热平衡方程,建立了煤炭表面水干燥所需热量在振动流化床干燥机长度方向上变化的数学模型,该模型表明,煤炭表面水干燥所需热量沿干燥机长度方向呈负指数急剧减少.根据这一特点,讨论了干燥机长度方向等速不等温进气、等温不等速进气、不等温不等速进气3种分区供热方式.采用床面积为1200mm×200mm的振动流化床干燥机进行了中间试验,结果表证明,所得模型与试验结果相符,即采用分区供热方式可降低干燥机出口气体温度和干燥能耗.     

径向机械通风仓干燥规律的实验研究及其过程的计算机模拟

本文通过实验对径向通风过程中的干燥规律进行研究.结合作者在前文得到的玉米薄层干燥方程建立了模拟径向通风干燥过程的数学模型及计算程序,并以实验数据进行了修正.该程序能够较好地预测玉米径向通风的干燥过程,为径向通风仓的设计与使用提供了迅速、简便而有效的工具.     

旋转闪蒸干燥设备的流体动力学分析

为探究旋转闪蒸干燥过程的流场特性及热质传递机理,应用计算流体动力学技术建立了此过程的CFD模型,模拟得到了干燥过程的速度场、温度场和压力场,分析了不同进风速度、温度、刀组转速对干燥性能的影响,并以碳酸钙为原料进行了试验验证.结果表明,干燥室内速度、温度及压力在近壁面区域均大于中心区域,随着高度增加总体呈衰减趋势,同时存在回流、漩涡等现象;不同进风速度、温度对压降影响明显,不同刀组转速对切向、径向速度有较大影响.     

气流干燥过程数值模拟

通过分析气流干燥的特点,建立的直管气流干燥模拟方程,采用Matlab语言调用标准四阶Runge-Kudra法,给出高精度的数值解。经验证,该模型正确可靠,具有较广泛的适用性,为模拟试验优化参数提供了分析基础。     

格子气自动机对多孔介质微观干燥过程的模拟

介绍格子气自动机方法的概念与原理，并用该方法对多孔介质液体吸附和微观干燥现象进行模拟，模拟得到了微观干燥过程湿分迁移特征及干燥特征曲线，模拟结果与文献相符合．初步研究表明，该方法可以用来研究微观的多孔介质干燥过程．     

云南核桃（Juglans sigillata Dode）对流干燥传质模拟

在菲克定律与质量守恒定律的基础上建立了模拟云南核桃干燥过程的一维非稳态传质数学模型．通过边界条件的处理,结合云南核桃热风干燥试验,对其干燥过程中内部各层水分分布进行了模拟预测．将含水率的预测值与试验值对比可知该模型与试验数据吻合得很好,试验条件下云南核桃的有效水分扩散系数变化范围为1.14×10－9～1.73×10－9 m2／s．干燥初期云南核桃表层的含水率下降速度比内层快得多,之后内层含水率下降速度比表层要快,最终各层含水率稳步下降;从表层到中心,湿度梯度随着干燥时间的增加逐渐减小．分析表明在核桃的干燥过程中,外壳是影响水分扩散的主要阻力之一．该模型有助于云南核桃干燥过程传热传质耦合的研究以及复杂模型的建立．     

Experiment research on grain drying process in the heat pump assisted fluidized beds

A heat pump assisted fluidized bed grain drying experimental system was developed. Based on this system, a serial of experiments was performed under four kinds of air cycle conditions. According to the experimental analysis, an appropriate drying medium-air cycle for the heat pump assisted fluidized bed drying equipment was decided, which is different from the commonly used heat pump assisted drying system. The experimental results concerning the drying operation performance of the new system show that the averaged coefficient of performance (COP) can reach more than 2.5. The economical evaluation was performed and the power consumption for removing a kilogram water from grains was about 0.485 kW·2222h/kg (H2O), which shows its reasonable commercial efficiency and great application potentiality in future market.     

循环流化床锅炉风室内流动特性及优化研究

一次风室是循环流化床锅炉的关键部件之一,其内部一次风流动分布的均匀性对循环流化床锅炉的高效运行至关重要。一次风气流分布不均匀会对锅炉燃烧产生不利影响,导致锅炉热效率降低。为了提高循环流化床锅炉的运行效率,采用数值模拟的方法研究设计合适的导流板。模拟结果表明,在一次风室内安装导流板后,一次风室内横截面处的气流速度不均匀性由81%降低到24%。为了验证数值模拟结果,采用了220 t/h循环流化床锅炉的缩小比例几何模型,在5种不同的实验条件下进行了可视化和速度分布均匀性实验。实验结果证实了数值模拟的正确性。此外,在一台220 t/h循环流化床锅炉上进行了热态实验。热态实验结果表明,在一次风室中加装导流板后,锅炉热效率由85.71%提高到88.34%,相当于每年节约5000 t标准煤,经济效益显著,证明了导流板的有效性。     

Combined Removal of Surface Moisture and Dust from Feed Coal for Coal Dry Cleaning with an Air-solid Fluidized Bed

A demonstration plant and a commercial plant employing coal dry cleaning technology with an air-solid fluidized bed were built in China. The operation practice of these two plants shows that the surface moisture and the fines or dust of feed coal must be well controlled as low as possible. For this purpose, a new process of combined removal of surface moisture and dust from feed coal using a vibrated fluidized bed dryer was investigated in a batch test apparatus and a pilot test system. A mathematical model on drying kinetics of coal surface moisture was developed and three empirical formulas of the model coefficient involving the main operating variables were determined based on the test results from the batch test apparatus. The mathematical model shows that the surface moisture retained in coal during drying decreases exponentially with drying time. According to this model, a new divisional heat supply mode, in which the inlet gas of higher temperature was introduced into the fore part of the dryer and the inlet gas of lower temperature into the rear part of the dryer, was employed in the pilot test system. The pilot tests show that 1） the new divisional heat supply mode is effective for lowering down the average temperature and reducing the total heat loss of the outlet gas off the dryer, 2） the moist coal of about 60 g/kg surface moisture contentcan be dried to about 10 g/kg, and simultaneously the fines （〈1mm in diameter） adhering to the surface of coarse coal particles are completely washed off by the gas flow.     

Study on drying and combustion process in grate-CFB incinerator

The drying and combustion process in the combined grate and circulating fluidized bed (grate-CFB) municipal solid waste (MSW) incinerator was investigated experimentally and mathematically. The drying grate bed was simulated by a muffle furnace, which could be controlled at a constant temperature level. The kind of wastes, thickness of waste layer fed and temperature were chosen as the adjustable parameters to study their effect on the drying process. The experimental results indicated that the hydrophilic wastes were more difficult to be dried than the hydrophobic wastes. The higher the temperature is the easier the waste is to be dried. The thinner waste layer is favorable to drying the waste. The pyrolysis experiment in the furnace showed that the higher temperature level could reduce the conversion rate of carbon to carbon monoxide. The semi-empirical mathematical model that included the bed material distribution submodel, volatile matter release submodel, carbon particle combustion submodel and so on was proposed. A 260 t/d grate-CFB incinerator was modeled and the model predicted bulk density agreed with the measured value from industrial field test. The predicted flue gas (e.g. CO₂, CO) concentration deviated slightly from the industrial test data. The parameters and variables used in the model were determined by the experiments or practical field test. This model can be used to design the grate-CFB incinerator and guide its operation. Supported by the National Natural Science Foundation of China (Grant No. 50776007)     

中药饮片干燥方法及质量预估的研究

研究了黄柏、甘草切片在振动流化床中的干燥,并与红外干燥作了对比．从实验结果可知,饮片在振动流化床中的干燥时间比红外干燥缩短了近95％．在一级反应动力学的基础上分析了干燥过程中有效成分的降解情况,结果表明,利用振动流化床干燥中药饮片,有效成分的损失量及能量消耗均比红外干燥少．     

聚丙烯腈干燥性能研究

利用洞道式循环干燥研究了当空气平行吹过聚丙烯腈物料层表面时的干燥特性，推导了凸凹不平颗粒状物料干燥表面的干燥面积蚣式及相应的干燥速率公式，讨论了干燥介质条件，物料层物性对干燥听影响，并得到初步结论。     

空气分级与空气重介流化床分选联合工艺研究

分析了固体颗粒在气-固流化床中的受力情况和运动方程，通过理论分析和实验得出了空气重介流化床分选入料的适宜粒级。讨论了空气重介流化床分选对入料粒度上下限的控制方法和存在问题，介绍了潮湿原煤空气分级新方法。试验表明，空气分级对潮湿原煤颗粒表面的煤粉有“清洗”作用，脱粉效果好，粗粒产物中含粉率仅为0.2%。这对控制入料粉量，稳定流化床密度和减少介质净化非常有利；空气分级还有分选作用，就试验煤种而言，其细粒级产物灰分比原煤中同粒级灰分降低1.7个百分点，比原煤灰分降低7.5个百分点，空气分级和空气重价流化床分选结合，可优化干法选煤工艺，降低工程投资和分选成本50%以上。     

Properties of concrete incorporating bed ash from circulating fluidized bed combustion and ground granulates blast-furnace slag

The properties of concrete incorporating circulating fluidized bed combustion (CFBC) bed ash and ground granulates blast-furnace slag (GGBS) were studied.Compressive strength,drying shrinkage,mercury intrusion porosimetry (MIP),scanning electronic microscopy (SEM),and X-ray diffraction (XRD) of concrete samples containing CFBC bed ash and GGBS were used.This work used initial surface absorption test (ISAT) and rapid chloride penetration test (RCPT) on concrete to measure the absorption and the ability of co...     

热泵型干燥室气流组织综述

在过去的十年中,由于对干燥农产品的高需求,在全球范围内引发了高密度热泵型干燥技术快速扩张. 干燥室内物料的干燥速率与气流分布有很大的关系,已提出了多种配置和方法来提高干燥室内的气流分布. 阐述了热泵干燥系统的运行原理和特点,分别从干燥室内部结构、工况设计、节能形式三大方面对国内外相关研究和案例进行综述. 指出了干燥室内气流分布不均匀是造成物料干燥效率低、不均匀和品质差的主要原因,分析了各种空气管理的办法,包括采用不同的送回风方式可避免干燥室内部形成回流,应用优化的几何结构可减小流体流动过程中的阻力,提高热泵干燥室内的综合性能. 指出需要进一步探索如何合理设计排湿口位置并对应设计不同的管道布置,以改善干燥室内热量及湿度的合理分布.     

Drying and preheating processes of iron ore pellets in a traveling grate

A mathematical model of drying and preheating processes in a traveling grate was presented based on the laws of mass, momen- tum, heat transfer, and drying semiempirical relations. A field test was systematically carried out in a traveling grate. The effects of pellet diameter, moisture, grate velocity, and inlet gas temperature on the pellet bed temperature were studied. The average relative error between actual measurements and simulations is less than 7.97%, indicating the validity of the model.