投加甲醛提高尿素成品粒度

在尿素市场竞争激烈的今天，产品质量是企业生死攸关的课题，辽宁锦西天然气化工有限责任公司尿素装置采用意大利斯那姆氧气提工艺，造粒塔造粒，尿素产品存在粒径小，粉尘多等缺点，每到夏季高温季节，成品粒度就会出现不同程度的下降，特别是在由于销售及其他原因造粒半成品尿素粒子在散装库内存放时间过长时，尿素颗粒结构变得疏松，强度降低，粒度下降，直接影响了产品销售价格和产品信誉，为了切实解决质量问题，该厂引入了在尿素中投加甲醛的方案。     

提高尿素粒度的有效方法

锦天化针对尿素粒度方面所存在的问题,组织开展了质量攻关。通过采用在高温多雨季节向尿素中加入甲醛的方法来提高尿素颗粒的强度;通过探究造粒喷头转速和造粒塔体内通风及空气湿度对尿素颗粒强度的影响,确定了保证尿素颗粒强度高的合理工艺参数;通过改进尿素的贮运系统,降低了尿素颗粒在贮运过程中遭受破损的几率、减少了粉尘的产生。历经几年的改进,锦天化提高了尿素粒度的质量,其尿素产品广受农民欢迎。     

提高尿素产品外观质量的措施与实践

尿素产品的质量含内在质量与外在质量两部分。内在质量指产品的总氮、缩二脲、水分等主要成分及铁、硫酸盐等杂质的含量。外观质量则主要指尿素颗粒的粒度和成品的馐情况，一般讲，工艺成就的生产装置，只要按设计条件操作。产品的内在质量指标是完全可以达到标准的，在此不作讨论，本文主要讨论尿素的粒度和强度问题。     

提高尿素颗粒强度的探讨

提高尿素颗粒强度的探讨胡蓉（赤天化集团有限责任公司，赤水，５６４７０７）１问题的提出尿素的内在质量包括总氮含量、缩二脲含量、水分含量和粒度等４项指标。赤天化集团有限责任公司生产的尿素总氮含量可达４６．５％，高于国际一级品４６．３％的要求。正常生产缩二...     

尿素产品质量影响因素浅析

对照尿素产品的国家质量标准,从缩二脲、水分、粒度、强度等方面分析了尿素产品质量未能达标的原因,提出并实施了工艺优化、设备改造、设备更新等措施。结果表明,尿素产品优级品率达到99．5％。     

提高尿素颗粒的机械强度

<正> 如同其他的无机肥料一样,粒状尿素应当满足下列基本要求:具有均匀的粒度组成[2—3毫米等级不少于50%(质量)]、颗粒的足够强度和不结块。颗粒的强度是由这些要求所决定的。在成品按照工艺流程转运、贮存和运输的情况下,强度主要影响成品粒度组成的改变。颗粒粉碎将引起细小等级的含量增大,以致增加结块并给尿素散装贮存和运输带来困难。我们按照从造粒塔到仓库的工艺流程,研究了尿素在输送过程中颗粒的强度及其破碎的程度。经过40次的分析试验择取了工艺流程上的每一个点,同时还记载了蒸发和成粒交叉点的技术规程指标。分析是按照尿素生产中所采取的分析控制方法进行的。颗粒的强度     

提高流化床造粒大颗粒尿素成品粒度的对策

针对大颗粒尿素成品粒度均匀度差、粒度偏低的问题进行分析,利用数据统计列表对比的方法找出影响大颗粒尿素成品粒度的主要因素,并制定相应的处理措施。改造措施实施后,大颗粒尿素成品粒度显著提高,年平均粒度达到96.6%,与2012年同比年平均粒度提高了0.9%,改善了大颗粒尿素成品外观质量,增强了尿素的市场竞争力。     

改进尿素包装工艺 不断提高产品质量

通过对尿素包装工艺的不断改进，提高了尿素粒度、减少粉尘含量，效果明显。     

巩固成绩迎接新的挑战

过去的2000年我们做了大量工作: 1.完成了2000年行业尿素质量抽样送检工作,检测结果表明,大化肥行业产品质量稳定,各企业尿素样品的质量都达到了国标优等品指标。 2.大化肥工艺先进,又经多年生产实践摸索,其尿素产品的总体质量是比较好的,但因大化肥多数采用塔式喷淋造粒(而非机械造粒),设计上的局限性,加之经常处于高负荷或超负荷下运行,使尿素的出塔温度和粒度、强度均受到影响,粒度虽能达到     

投加甲醛提高尿素成品粒度

采用在尿素中投甲醛的方法，改善尿素外观质量，提高尿素产品粒度，达到生产优质尿素，增强市场竞争能力的目的。     

尿素合成塔衬里贴衬板材的选择与应用

根据现场施工的具体情况,考虑材料的强度、耐蚀性及工艺操作特点,在尿素合成塔衬里实施贴衬时,选用国产4.2mm厚的25-22-2冷轧钢板,从而解决尿素合成塔衬里腐蚀减薄的问题。     

Thermal and mechanical properties of plastics molded from urea-modified soy protein isolates

Soy protein has been considered as a potential alternative of some petroleum polymers in the manufacture of plastics. The purpose of this investigation was to characterize the thermal and mechanical properties of plastics made from urea-modified soy protein. Soy protein isolate was separated from the defatted soy flour, modified with various urea concentrations, and compression-molded into plastics. Differential scanning calorimetry showed that the temperatures of denaturation and the enthalpies of denaturation of the modified soy protein decreased as urea concentrations increased above 1 M. At the same urea concentration, molded plastics made from the modified soy proteins showed a similar temperature of denaturation as the modified soy protein, but a lower enthalpy of denaturation. Tensile strength and Young's modulus of the molded plastics from the modified soy proteins increased as urea concentration increased and reached their maximum values at 8 M urea modification. Both storage modulus and glass transition temperature of the plastics from the modified soy proteins increased as urea concentration increased. The plastics made from the 2 M urea-modified soy proteins showed improvements in elongation, tough fracture behavior, and water resistance. The urea may function as a denaturant, a plasticizer, and a filler.     

压缩机转子与运动件碰撞的振动特征简析

引起大机组转子振动异常的因素很多,本文以泸天化股份有限公司尿素装置二氧化碳压缩机高压缸转子振动异常的故障为例,通过对其症兆信号与常见故障特征信号的分析比较,提出转子与运动件碰撞引起振动异常的一些特点,期望以此对大机组类似故障的诊断有所裨益.     

蛋白质水力学半径的测定及用于蛋白质变性过程的实时监控

采用纳米粒度分析仪Zetasizer Nano测定了牛血清白蛋白（BSA）的水力学半径,考察了pH、离子强度、表面活性剂等的影响,并用于BSA热变性和脲变性过程的实时跟踪。随pH增大,BSA水力学半径呈“U”形变化趋势;酸性条件下,分子膨胀,随着盐浓度升高,BSA分子先小幅减小后显著增大;中性pH范围,离子强度对蛋白质分子尺寸影响很小,蛋白质性质相对稳定。离子型表面活性剂在蛋白质表面吸附,从而影响BSA水力学半径。通过水力学半径的测量实时跟踪蛋白质变性过程的分子变化,发现增加热变性中离子强度可加快变性速率,SDS加入增大了BSA变性温度Tm。脲在促使BSA分子扩张的同时,对链伸展有抑制作用;在DTT存在下,BSA的水力学半径随着时间变化逐渐增大。结果表明,简便的水力学半径测量可以用于蛋白质大小的表征,并可实时跟踪蛋白变性过程的分子尺度变化。     

DJS—b电子计数器的改造及成功应用

叙述对ＤＪＳ－ｂ电子计数器进行的部分重要改造，使之成为技术性能比原来高得多的ＧＤＪＳ－１光电计数器。该光电计数器在建峰化工总厂尿素袋装码头商务计量交接上得到了成功应用。取得了明显的经济效益和社会效益。     

Polyurethaneurea–silica nanocomposites: Preparation and investigation of the structure–property behavior

Nanocomposites consisting of thermoplastic polyurethane–urea (TPU) and silica nanoparticles of various size and filler loadings were prepared by solution blending and extensively characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), thermal analysis, tensile tests, and nanoindentation. TPU copolymer was based on a cycloaliphatic diisocyanate and poly(tetramethylene oxide) (PTMO-2000) soft segments and had urea hard segment content of 20% by weight. TPU/silica nanocomposites using silica particles of different size (29, 74 and 215 nm) and at different loadings (1, 5, 10, 20 and 40 wt. %) were prepared and characterized. Solution blending using isopropyl alcohol resulted in even distribution of silica nanoparticles in the polyurethane–urea matrix. FTIR spectroscopy indicated strong interactions between silica particles and polyether segments. Incorporation of silica nanoparticles of smaller size led to higher modulus and tensile strength of the nanocomposites, and elastomeric properties were retained. Increased filler content of up to about 20 wt. % resulted in materials with higher elastic moduli and tensile strength while the glass transition temperature remained the same. The fracture toughness increased relative to neat TPU regardless of the silica particle size. Improvements in tensile properties of the nanocomposites, particularly at intermediate silica loading levels and smaller particle size, are attributed to the interactions between the surface of silica nanoparticles and ether linkages of the polyether segments of the copolymers.     

PVC螺旋管的生产及改进

介绍了PVC螺旋管生产的方法及存在的问题，通过分析，采用了在配方上减少硬料中的外润滑剂、共混改性和机头口模处进行改进的办法，有效地提高了PVC螺旋管的粘接强度。     

Evaluation of properties of starch-based adhesives and particleboard manufactured from them

The objective of this study was to evaluate some of the mechanical and physical properties of experimental particleboard panels manufactured from rubberwood (Hevea brasiliensis) bonded using oil palm starch, wheat starch, and urea formaldehyde (UF) at a density of 0.60 g/cm³. Bending characteristics, internal bond strength, thickness swelling, and water absorptions of the samples were determined based on Japanese Industrial Standard (JIS). Overall mechanical properties for natural binder oil palm starch resulted in higher values than those made from wheat starch. The highest internal-bonding strength (IB) value of 0.41 N/mm² was determined for the samples made from oil palm starch. Dimensional stability in the form of thickness swelling of the samples made from oil palm starch had higher values, ranging from 4.24 to 22.84% than those manufactured from wheat starch. Natural adhesive showed comparable strength with panels manufactured with UF. Overall results meet the Japanese Industrial Standard (JIS) requirements except for water absorption and thickness swelling of the samples.     

污水厂污泥制地砖及其性能

参照普通陶瓷砖的生产工艺,烧制污泥地砖,对其抗压、抗折、抗磨损性能、腐蚀性能及影响因素进行检测和分析,以探讨用城市污水处理污泥制造地砖的可能性.实验表明:随污泥含量增加,烧制成品的抗压强度显著下降,抗折强度略有增加.细粒径污泥粉配料有利于提高制品整体强度.采用复合材料结构可提高制品的抗压强度.成品的抗磨损性能优于普通砖的,略低于普通市售陶瓷砖的.这种地砖的水浸出液不具有腐蚀性能,且污泥中所含重金属Mn,Cu被很好固化在砖中而不能渗出.     

十二烷基苯磺酸钠辅助尿素共沉淀制备超细铜铬黑颜料

以十二烷基苯磺酸钠为表面活性剂,采用尿素共沉淀法合成超细尖晶石型铜铬黑颜料。以铬和铜硝酸盐为原料,系统研究了沉淀剂、煅烧温度和表面活性剂等条件对铜铬黑颜料晶型、形貌和粒度的影响;并探讨了合成条件对铜铬黑颜料着色力的影响。研究表明,尿素和十二烷基苯磺酸钠可有效地控制形貌、颗粒大小及均匀性;在尿素用量为理论量4倍、表面活性剂添加量为5%、煅烧温度800℃的条件下制备出了形貌为六面体、平均粒径为300 nm、粒径分布均匀、着色力优异的超细铜铬黑颜料。