喷气燃料储存安定性的研究

对喷气燃料的储存安定性进行了探讨,对喷气燃料的氧化机理进行了详细的研究,对常用抗氧剂进行了对比,对喷气燃料的颜色安定性及蒸发损失进行了阐述,并对未来进行了展望。     

气相法合成N-乙基苯胺工艺条件和催化剂的研究

基苯胺的催化剂进行了筛选,找出了活性最好的催化剂。在最佳工艺条件下,对该催化剂进行了稳定性考察,对产品进行了精馏实验。用NH₃-TPD法测定催化剂的表面酸性,并对催化剂的表面活性和酸性进行了关联,确定了苯胺的N-乙基化是在较弱的L酸上进行的。采用工业放大催化剂进行了工业试生产。     

MCS-51系统DA A指令浅析

本文就单片机的DA A指令出现的前提、指令的调整规则、指令的其它功能几方面进行了全面的分析。关于本指令的调整规则,文章采用了完全列举法进行了证明,并举例进行了验证;对于指令"减1"的功能,也详细进行了说明,同时给出了实例进行了验证。     

高速剪切机浮动送料机构的运动学分析

提出了满足送料机构平动要求的平行四边形浮动送料机构,对浮动送料机构进行了结构设计,利用矩阵理论对其进行了运动学分析,建立了从动件的位置参数矩阵,从而利用现有的标准计算机程序进行求解,对机构进行了优化设计.     

黄磷尾气净化脱硫模拟工艺试验

对黄磷尾气净化脱硫进行了模拟工艺试验。测定了黄磷尾气中硫化氢的含量。对吸收、吸附条件进行了试验研究 ,用两种工艺进行了组合 ,对组合工艺进行了比较。得出了最佳的黄磷尾气净化脱硫工艺     

重整反应器的修复

对超期服役的重整反应器出现的问题进行了分析,制定了可行的修复工艺,对设备进行了返修,并对返修后的情况进行了分析总结。     

新型化学甲醛清除剂的发展概况

从室内装修、纺织品的角度对甲醛来源及危害进行了简要介绍,概括了清除甲醛的物理方法和化学方法,重点对新型化学甲醛清除剂的发展进行了总结,并对其特点进行了简要分析,最后对甲醛清除剂用于空气净化器进行了展望。     

油气井金刚石钻头的使用探讨

结合不同因素对油气井金刚石钻头的选型进行了分析,对水力参数的选择进行了考察,对钻头下井前的工作进行了细致描述并对钻头的使用操作进行了探讨,最后对井下异常情况的处理做了说明.     

对自吸式氢化釜搅拌轴的修复

对一搅拌轴的磨损原因进行了分析 ,对搅拌轴的两种修复方案进行了比较 ,并对各自的可行性进行了分析     

氨苄西林钠制备方法的研究

通过对氨苄西林钠各种生产工艺进行分析比较,对影响澄清度稳定性的因素进行了推断,进而开发了乙腈溶媒结晶新工艺,并对乙腈溶媒结晶工艺各操作条件的变化对产品质量及收率的影响进行了系统研究,最后对乙腈工艺进行了优化.     

我国粮食主产区尿素供需时空特征及市场调控思路

在总结前人研究的基础上,重点从季节和作物角度对我国粮食主产区尿素供需状况作了深入分析。研究结果表明,我国粮食主产区尿素全年的总体供应量大于需求量,但季节间和区域间供需却不平衡。3月和7月是尿素消费高峰期,易发生供应不足,而尿素消费和生产区域分布不一致导致消费旺季供需矛盾更加突出,是导致价格波动和运输困难的主要原因。针对尿素供需矛盾,对我国化肥产业的宏观调控策略提出了一些想法,以期为我国化肥产业和农业的健康稳定发展提供依据。     

利用尿素洗涤回收技术降低解吸废液中的尿素含量

应用尿素洗涤回收塔 ,降低解吸废液中的尿素含量 ,回收大部分尿素 ,取得了环保和经济双重效益。     

垂直筛板型尿素工艺冷凝液深度水解装置运行总结

介绍了垂直筛板型尿素工艺冷凝液深度水解装置投产及运行情况。实际运行结果表明:装置处理能力25 m3/h,吨工艺冷凝液蒸汽耗≤300 kg,水解后废液中含氨和尿素质量分数均≤5×10-6,回收的NH3和CO2全部返回尿素装置的中压系统,吨尿素氨耗下降10～15 kg,收到了较好的节能减排效果。     

Dissolution and stability of chitosan in a sodium hydroxide/urea aqueous solution

Medium‐molecular‐weight chitosan (MMWC; 157.5 kDa) and low‐molecular‐weight chitosan (LMWC; 53.4 kDa) samples were dissolved in an NaOH/urea solution by freeze–thaw treatment. The factors affecting dissolution were optimized, and the stability of chitosan in the produced solution was investigated. NaOH and urea concentrations of 2 and 0.67 mol/L, respectively, and a treatment temperature of ?18°C were optimized as the dissolving conditions. MMWC and LMWC could be completely dissolved in the 2 mol/L NaOH/0.67 mol/L urea solution after six and five cycles of freeze–thaw treatments, respectively. Dissolution and storage in the 2 mol/L NaOH/0.67 mol/L urea solution slightly increased the deacetylation degree of chitosan and slightly decreased the molecular weight. The solution stability of LMWC was better than that of MMWC. MMWC tended to form a gel during storage. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39819.     

Effect of urea and formamide plasticizers on starch/PVA bioblend sheets

The starch/polyvinyl alcohol (PVA) bioblend sheets containing urea and formamide as plasticizers were prepared through melt processing in presence of water. The experiments indicated that urea and formamide plasticizers could form strong hydrogen bonds with starch/PVA molecules. Urea exhibited better plasticizing effect than formamide. Urea also could greatly destroy the crystal structures of PVA component in the blends, leading to the decreased crystallinity of the blends. Formamide was a good solvent for urea and could prevent urea separating from the blends, resulting in the improved stability of plasticizing systems. The blends exhibited good flexibility. Therefore, the incorporation of both urea and formamide into starch/PVA blends could exhibit synergistic effects to ensure the blends with both good plasticizing effect and the stability of the plasticizing systems. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42311.     

从尿素工业发展的历史看现有全循环法流程技术改造的必要性

在回顾尿素生产的工业化及工艺流程演变的基础上,提出不同尿素工艺评价的原则,认为我国现有水溶液全循环法尿素装置的改造必须在降低蒸汽和电耗上下功夫,并给出降低消费的主要措施。     

Compaction of metal salt-urea complexes with triple superphosphate

It has been the experience of the fertilizer industry that urea should not be cogranulated or blended with superphosphate because urea reacts with monocalcium phosphate monohydrate (MCP·H₂O) in superphosphate to form an adduct. This reaction releases the water of hydration and causes the product to become wet and sticky or severely caked during storage. The objectives of this study were [1] to test the feasibility of preventing or retarding the reaction by complexing the urea with various salt hydrates and [2] to measure ammonia volatilization from metal salt-urea complexes on the soil surface.Three metal salt-urea complexes — Al(urea)₆(NO₃)₃, Fe(urea)₆(NO₃)₃, and Mn(urea)₄Cl₂ — were prepared and cogranulated by compaction with pure MCP·H₂O or triple superphosphate (TSP) at a mole ratio of MCP:urea as 1:2. These materials were then compared with the same material without metal salts in terms of changes in free water content during a storage period of 6 weeks. Without metal salts a rapid and significant increase in free water content of the cogranulated MCP·H₂O + urea or TSP + urea was observed. The increases in free water content were found to range from 1.5% to 1.8%, corresponding to approximately 63% and 78% of the added MCP·H₂O that reacted with urea in the cogranulated products. On the other hand, little change or only a slight increase (less than 0.5%) in free water content was observed with the cogranulated metal salt-urea complexes.Ammonia volatilization losses from urea on the soil surface were measured in a period up to 14 d with two soils: Windthorst (pH 7.6) and Savannah (pH 7.0). The fertilizer materials used were granular. In Windthorst soil, the amounts of NH₃-N lost were 25% for prilled urea, 11% for Mn(urea)₄Cl₂, and essentially none for Mn(urea)₄Cl₂ compacted with TSP at a mole ratio of MCP:urea as 1:1 or 1:2. In Savannah soil, the amounts of NH₃-N lost were 39% for prilled urea, 24% for Mn(urea)₄Cl₂, 15% for Fe(urea)₆(NO₃)₃, and less than 6% for each of the two metal salt-urea complexes compacted with TSP. The acidity that resulted from metal complexing of urea reduced NH₃ volatilization from hydrolyzed urea in soils, and additional acidity produced from hydrolysis of MCP·H₂O further reduced NH₃ losses when materials were applied as multicomponent granules (metal salt + urea + TSP).     

尿素应用新领域及其发展前景综述

介绍了脱硝尿素和车用尿素在SCR技术中的应用概况及其今后在国内尿素市场消费中的前景。脱硝尿素和车用尿素的应用是燃煤烟气和汽车尾气的排放最能够直接见到效果的控制大气污染物的一个重要措施。     

造粒喷头对尿素外观质量的影响与对策

分析“TUTTLE”梯形斜孔造粒喷头在实际生产过程中对尿素外观质量的影响。针对喷头存在的问题,采取相应改进措施,提高了尿素外观质量。     

斯那姆氨汽提尿素装置蒸汽冷凝液系统改造

尿素装置和三聚氰胺系统联运后,三聚氰胺返回尿素的工艺碳铵液造成尿素系统水碳比增高,尿素转化率下降,中、低压系统负荷增加,蒸汽冷凝液系统超温超压。针对存在问题对尿素蒸汽冷凝液系统进行改造,改造后实现了效益的最大化。