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针对颗粒和空气在干燥管内的相互作用和传质传热机理,首先建立了直管式气流干燥数学模型,然后通过分析脉冲式气流干燥器的结构特点,求出了管径变化的微分方程,将其和直管式气流干燥的五个常微分方程耦合在一起,构成了脉冲式气流干燥的传质传热数学模型。根据模型方程的特点,运用四阶龙格-库塔法对其进行了数值求解。通过实验结果验证,该模型正确可靠。 相似文献
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<正> 一、绪言磷酸氢钙是骨明胶制造业中的副产品之一。在制造明胶过程中,兽骨经盐酸浸渍脱去无机盐,所得到的乏酸溶液(含HC10.22~0.30%),经过脱氟、过滤、合成、离心脱水、干燥、筛分、包装,即得到有两个结晶水的磷酸氢钙。磷酸氢钙的干燥,一般都是采用气流干燥法。其优点是:干燥速度快,传质传热速率大,物料受热史短,易于干燥热敏性物料,装置结构简单,干燥处理量大;适合于批量大的细小颗粒物质的干燥。磷酸氢钙的产品质量,各企业由于受工艺和设备等各种因素所限制,产品顷量不稳 相似文献
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基于加热均匀性的微波干燥研究进展 总被引:1,自引:0,他引:1
微波干燥通过电磁场辐射物体而在其内部产生热量,促进物体内部水分向外部迁移,是一种先进的干燥技术。但是,微波干燥存在加热不均匀的问题。本文针对该问题,分析了导致微波加热/干燥不均匀的影响因素,综述了通过提高微波干燥室内电磁场分布均匀性及改变被处理物料位置,以改进微波加热均匀性的可行措施,最后指出进一步实现微波均匀干燥的研究发展趋势。 相似文献
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2种方式干燥的天然橡胶干燥特性之研究 总被引:2,自引:0,他引:2
为探讨微波干燥天然橡胶新技术,分别在温度115℃下,采用电热烘箱产生热空气和微波干燥装置干燥湿天然橡胶胶粒,对二者的干燥特性及硫化胶性能进行对比分析研究。结果表明,微波干燥只需13.467min就可使胶料含水量降至0.791%,热空气干燥则需211min。天然橡胶微波干燥和热空气干燥主要包含失水率加速期、失水率减速期、失水率相对恒速期3个失水阶段。整个干燥过程中,微波干燥失水率较大,而热空气干燥失水率比较小。微波干燥天然橡胶硫化胶的耐热氧老化性能得到显著提高:其老化前后拉断伸长率变化率(-35%)和拉伸强度变化率(-59%)明显高于热风干燥天然橡胶硫化胶的拉断伸长率变化率(-62%)和拉伸强度变化率(-89%)。 相似文献
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介绍了一种大型气流干燥磷酸氢钙的工业生产流程,对干燥管内颗粒和空气的干燥特性进行了模拟和计算机辅助设计,模拟设计结果与实际生产情况较吻合。 相似文献
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由我院生后研制和设计成功的饲料磷酸氢钙和牙膏,食品添加剂(食用磷酸氢钙)项目中,其技术关键为脱氟和气流干燥,而物料在进行气流干燥时,温度,压力的测量和控制,是保证产品的产品质量的重要手段,本文介绍了工艺中仪表设计经验。 相似文献
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对自制的低溴化天然橡胶(BNR)的溴含量、红外谱图、在甲苯中溶解性能、不饱和度及综合力学性能进行研究分析。结果表明:随着反应过程中溴化液用量的增加,制得的低溴BNR的溴含量也增大,且溴含量不与溴化液用量成线性正比关系;溴化天然胶乳的红外光谱分析表明,溴已经接到天然橡胶分子链上,其C-Br键对应的红外光谱位置分别为956 cm-19、08 cm-1;在常温下,低溴BNR在甲苯中溶解性较差,在水浴加热70℃情况下,对低溴BNR在甲苯中的溶解性略有改善,同时随溴含量的增加,溶解性也越差。经塑炼后的低溴BNR在水浴加热70℃的情况下,对低溴BNR能完全溶于甲苯溶剂中;制得的低溴BNR的不饱和度略有降低,不饱和度随溴化液用量的增加变化不大;低溴BNR的加工性能总体较好,经溴化后的天然橡胶较纯胶的综合力学性能都有所下降,其中当硫磺用量为2.7份时,综合力学性能相对较好。 相似文献
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Si-Dong Li Ying Chen Jiang Zhou Pei-Sen Li Cheng-Shen Zhu Mu-Liang Lin 《应用聚合物科学杂志》1998,67(13):2207-2211
The thermal degradation and thermooxidative degradation of epoxidized natural rubber (ENR) were studied by thermogravimetry (TG). In the thermal degradation of ENR, the initial temperature of weight loss T0 = 1.20B + 348, the temperature of maximum weight loss rate Tp = 1.07B + 392, and the final temperature of weight loss Tf = 0.77B + 445. The Cp, which corresponds to the degradation rate at temperature Tp, increases along with the heating rate B and its mean value is 43%, but Cf, which corresponds to the degradation rate at temperature Tf, is not affected by the heating rate, and its average value is close to 100%. As in the thermooxidative degradation, T0 = 1.84B + 246, Tp = 0.30B + 378, and Tf = 2.27B + 584. The value of Cp increases along with the heating rate B and its mean value is 36%, but Cf is not affected by the heating rate and the average value approximately equals 100%. The thermal degradation in nitrogen could be a one-step reaction, whereas the thermooxidative degradation has a multiple-step reaction. The reactive environment has a great effect on the thermal degradation of ENR and the difference of the mechanisms of the two reaction systems is obvious. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:2207–2211, 1998 相似文献
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The effects of pH value of reaction system, reaction time, and reaction temperature on the chlorination reaction in the preparation of chlorinated natural rubber (CNR) from natural rubber latex were discussed. It has been found from the thermal analysis that the thermal degradation of CNR in nitrogen is a one-step reaction, and 30% carbonide with a stable structure remained at 360 to 700°C; whereas the thermo-oxidative degradation of CNR in air is a multistep reaction, and the thermal degradation ratio reaches to 100% at 560°C. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2863–2867, 1999 相似文献
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A solid-state chemical reaction occurs when a solvent cast film of a blend of masticated natural rubber and chlorinated natural rubber is heated in the presence of air at 150°C. The thermal behavior of solvent cast films of chlorinated natural rubber, masticated natural rubber, and a 1 : 1 w/w blend (2% w/v in xylene) of these two polymers has been studied using differential scanning calorimetry, infrared spectroscopy, scanning electron microscopy, and nuclear magnetic spectroscopy. The results suggest that carbonyl groups are incorporated into the blend on heating and that the vinyl functionality of the isoprene units is modified during this apparent oxidation. Heating for 2 h at 150°C results in a material that no longer contains the rubber-like cis-1,4-polyisoprene units. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 1379–1384, 1997 相似文献
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环氧化天然橡胶的研究与应用 总被引:5,自引:0,他引:5
环氧化天然橡胶(ENR)是由NR化学改性而成,笔者阐述了环氧化天然橡胶制备原理和方法、环氧化天然橡胶性能及应用研究、环氧化天然橡胶共混改性研究,其中包括ENR与PVC共混体系的研究、ENR其它共混体系的研究和ENR改性的研究. 相似文献