共查询到18条相似文献,搜索用时 78 毫秒
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熔融结晶可应用于同系物、共沸物、热敏性物质等特殊物系的分离,因其分离纯度高、能耗低、工业放大操作方便等优点获得广泛认可。乙烯焦油、重整芳烃、煤焦油等劣质重芳烃中含丰富的萘、对二甲苯、均四甲苯、蒽、菲、咔唑、苊等一系列高附加值化学品,熔融结晶在上述高附加值化学品的分离提纯中有重要作用,其中多数为间歇操作。目前,对于连续大规模工业化生产已取得阶段性进展,但堵塞和结垢仍是制约其发展的关键问题。结晶过程中传质传热的理论研究对于指导未来新型结晶器和模型的开发具有重要意义。 相似文献
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针对低温甲醇洗工艺中的CO2-NH3-H2O-CH3OH平衡体系,通过模拟该体系下碳酸氢氨的静态、动态溶解度实验,研究该体系下的结晶热力学。静态实验结果表明,碳酸氢铵溶解度和温度正相关,当体系中CH3OH摩尔分率Xc>0.3时,离子间的静电力成为结晶的主导因素,溶解曲线逐渐趋于平缓。动态实验结果表明,当Xc>0.3后,体系介稳区几乎消失。利用Design-Expert软件设计实验,并拟合实验结果,得出热力学回归方程:Xa=0.008 6-0.006 0A+0.002 0B+0.006 3T+0.001 0AB-0.001 8AT+0.005BT+0.002 2A2+0.002 2B2+0.003 1T2。该方程F值为143.95,失拟误差为<0.000 1,残差符合正态分布,回归方程结果可靠,可用于预测不同工况下系统的结晶分布。 相似文献
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建立了顶空-气相色谱法,对生物柴油副产物粗甘油中的甲醇含量进行测定。将粗甘油样品用水溶解,加入1,4-二氧六环作内标,90℃下顶空平衡45 min,在HP-INNOWax柱上进行分离和测定。实验结果表明,甲醇溶液的质量浓度在0.8~40.0 g/L范围内呈良好的线性关系,相关系数r>0.999,样品中甲醇质量分数的测定低限为0.005%。对实际样品进行测定,相对标准偏差在0.9%~1.6%(n=8),加标回收率在94.0%~106.0%。该方法操作简便,精密度好,结果准确,对仪器系统污染小,适用于粗甘油中甲醇含量的测定。 相似文献
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Layer melt crystallization was applied for the dry fractionation of multi-component mixtures using coconut oil as a model substance. The aim of the experiments was to optimize the crystallization parameters (e.g. crystallization temperature, melt temperature, cooling rate, agitation speed) in order to obtain the solid fraction with a higher melting temperature and solid fat properties. The isothermal crystallization behavior of coconut oil was investigated via differential scanning calorimetry (DSC). The efficiency of the crystallization process was monitored by determining the melting point and solid fat content (SFC) of the fractionated products. The morphology of crystal layer was studied by a light microscope. Cool finger temperature was found to have the greatest impact on product properties. Applying a cooling rate of 0.2 K/h resulted in sufficient growth rates providing the required products. The micrographs of the solid fraction revealed lamellar particle arrangement compared to coconut oil possessing spherulites. 相似文献
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The melting and crystallization behaviors of palm oil were examined by nuclear magnetic resonance, differential scanning calorimetry,
and plasticity measurements and were correlated with composition and chemical characteristics. Fractionation into high melting
and low melting components is adversely affected by increase in free fatty acids (FFA), diglyceride content, and degree of
oxidation, and hence, for an oil that is to be fractionated, both hydrolysis and oxidation should be kept to a minimum. Palm
oil with very low FFA content, obtained from ripe, unbruised fruit, contains substantially more diglycerides than would be
expected from the level of FFA present. Liquid and solid palm oil fractions manufactured in the producing countries showed
large variation in characteristics, due in part to the use of various fractionation processes. The characteristics used to
define the quality of palm oil are also applicable to its fractions. 相似文献
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采用冷冻结晶工艺对钛白副产硫酸亚铁进行了提纯研究,重点考察了结晶母液循环时镁、锰杂质的累积情况以及它们的去除规律,同时对可能引入体系的钠杂质影响也进行了研究。通过多次结晶可以逐渐降低七水硫酸亚铁晶体中镁、锰杂质含量,但结晶母液的循环会导致体系内镁、锰杂质逐渐累积。利用结晶液与结晶体中镁、锰含量的关系曲线推断得到:当结晶液中镁含量低于298 mg/L时,七水硫酸亚铁晶体中镁质量分数将低于0.025%;当结晶液中锰含量高于761 mg/L时,七水硫酸亚铁晶体中锰质量分数将高于0.05%。另外,结晶法提纯硫酸亚铁时应避免向体系中引入钠离子,否则会导致七水硫酸亚铁晶体中钠杂质含量超标问题。该论文研究结果可以为利用结晶法提纯钛白副产硫酸亚铁提供一定的理论和技术指导。 相似文献
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