尿素熔融喷涂在S—NPK复合肥生产中的运用

在转鼓喷浆涂布造粒制复合肥的基础上,增加尿素熔融喷涂补充氮养分的工艺技术.介绍了尿素熔融喷涂技术的工艺流程、特点,主要工艺指标和主要设备,以及装置改造措施和效果.利用尿素熔融喷涂生产复合肥,可显著提高生产能力,产品圆润光滑,不易结块.     

多元大颗粒尿素生产工艺

多元大颗粒尿素生产工艺的原料选用晶状硫酸铵和富含钙镁等中量营养元素的矿物质。整个工艺分原料预处理工序、混合造粒工序和产品后处理等工序。为了使固体原料能与尿素熔融液形成良好的悬浮液 ,并在加入原料时不致造成尿素熔融液的局部结晶 ,在原料预处理工序将原料破碎、研磨至一定细度 ,再加热至接近尿素熔融液的温度 ,最后送至造粒前混合器中与尿素装置来的尿素熔融液混合。混合器内设有搅拌装置 ,并控制物料的停留时间 ,使产品的缩二脲含量控制在尿素产品的许可范围内。出混合器的悬浮物直接送到尿素造粒塔造粒器进行造粒 ,该造粒器在…     

熔融尿素泵转子结构部件的改造

对赤天化集团责任有限公司尿素装置中熔融尿素泵经常损坏的原因进行分析，实施对转子部件的改造和使用推广情况     

尿基NPK生产工艺及装置优化运行途径探讨

介绍了尿基NPK生产工艺及特点，针对以熔融尿素为原料，采用半料浆团粒法造粒生产尿基NPK装置在运行中出现的问题，结合熔融尿素和尿基NPK的物化特性进行分析，提出解决这些问题的相应对策，并强调了严格操作管理对装置长周期、满负荷运行的重要性。     

尿素系统造粒控制阀的改造

中原大化集团的尿素装置是我国从意大利斯那姆公司引进的第1套氨汽提节能型生产工艺装置。调节阀HV-09601是熔融尿素通往造粒或循环的重要三通控制阀(见图1),此阀的正常与否直接影响到尿素系统的正常运行。     

安徽晋煤中能海藻尿素装置建成投产

<正>安徽晋煤中能化工股份有限公司海藻尿素装置2014年2月24日建成投产并稳定运行。海藻尿素是在造粒过程中,将预先制备好的浓缩海藻提取液与熔融尿素溶液按照一定比例均匀混合,其中,浓缩海藻提取液与尿素加入重量比例为50~200∶1000,然后在造粒塔造粒。浓缩海藻提取液与熔融尿素造粒后,浓缩海藻提取液最终以海藻精华固形     

高压氨加热器内管泄漏原因分析及对策

中原大化集团有限公司的三聚氰胺装置是目前国内单系列生产规模最大、工艺技术居世界领先的3万t／a大型三聚氰胺生产装置。该装置采用美国应用信号技术的高压尿素法生产工艺,由浓度99．8％的熔融尿素与过热氨混合后进入三聚氰胺反应器,在8．0MPa和380℃的条件下反应,生成三聚氰胺。由于反应过程以气氨为载体,于是高压氨加热器成为将液氨加热成气氨作为熔融尿素载体的关键设备。然而,该设备在生产过程中经常发生内管泄漏,严重影响三聚氰胺装置稳定运行。     

镍含量分析小结

尿素成品及合成塔出口熔融物中镍含量的测定，是尿素生产装置高压系统平均腐蚀程度的依据。尿素合成塔衬里与塔板及一些设备管件的材质均为不锈钢，在高温、高压下的尿素一甲铵介质作用下，每时每刻都有镍不断溶解下来，尿素成品、尿素合成塔出口熔融物中含镍就是这种腐蚀作用的客观反应，所以测定尿素合成塔中镍的含量在生产中是重要的控制分析项目。     

提高产品质量降低尿素水份

二氧化碳汽提法尿素装置设计成品中的水份为0.30%(重量),而实际生产中,特别是夏季气温高、湿度大,成品中水份就更难以控制。尿素颗粒中水份含量的多少,主要取决于两个因素,一是二段蒸发后的熔融尿素中水份含量的多少,二是熔融尿素在造粒塔内被空气冷却过程中,吸收还是放出水份的多少。二段蒸发后的溶融尿素中水份     

会议报道

50F,M-70型熔融尿素泵通过鉴定由沈阳化工机械厂研制(本溪化肥厂协作)的J50F,M-70型熔融尿素泵,于4月18日通过了由辽宁省石油化工局组织的技术鉴定。 50F,M-70型熔融尿素泵,是11万吨/年尿素生产装置的关键设备之一,它吸入口径为1.0毫米,是单级、单吸、单端面机械密封的悬臂式耐腐蚀离心泵,流量Q=17米~3/小时,扬程H=70米(水柱),功率N=17千瓦,使用温     

Anti- and Prooxidant Properties of Carotenoids

Carotenoids can be effective singlet oxygen quenchers and inhibit free-radical induced lipid peroxidation. A remarkable property of β-carotene ( 1a ) is the change from an antioxidant to a prooxidant depending on oxygen pressure and concentration. In the present study a considerable number of carotenoids ( 1a , 2c , 2d , 2e , 3a , 4a , 5a , 6a , 7a , 8a , 8h , 8i , 8j , 9f , 10a , 11a , 12g ) was investigated using two independent approaches: 1. Comparison of their effects on inhibition of the free-radical oxidation of methyl linoleate, and 2. The direct study of the effect of oxygen partial pressure upon their rates of oxidation. It is shown that some carotenoids ( 7a , 8a ) are even more effective than the well-known compounds β-carotene ( 1a ) and astaxanthin ( 5a ) and are powerful antioxidants without any prooxidative property. Different carotenoids display different behaviour depending on chain length and end groups. The influence of these functional groups on the antioxidative reactivity is discussed.     

国内外己内酰胺生产现状及市场分析

世界上最大的5家己内酰胺生产商是德国BASF公司,生产能力为55.5万T/a;荷兰DSM公司,生产能力为42.0万t/a;美国Allied-Signal公司,生产能力为32.7万t/a;日本宇部兴产公司,生产能力为26.8万t/a;日本东丽公司,生产能力为17.0万t/a。这5家公司的已内酰胺生产能力合计为174万t/a,约占世界总产量的50％。中国目前有4套己内酰胺生产装置,岳阳巴陵鹰山石化厂,2000年生产能力为7万t/a;南京东方公司,生产能力为6万t/a;石家庄化纤公司,生产能力为5万t/a;浙江巨化公司锦纶厂,生产能力为0.45万t/a,全国合计年生产能力为18.45万t/a。国外己内酰胺的主要消费领域为纤维、工程塑料和食品包装膜;国内已内酰胺的主要消费领域为帘子布、民用丝、工程塑料,所占比例分别为70％、28％、2％。国内己内酰胺需求一直大于国内产量,但由于技术力量薄弱、资金有限及下游产品结构不合理等原因制约了己内酰胺的应用,目前国内的已内酰胺主要应用在中低档产品中,高档产品所需己内酰胺仍要依靠进口。     

Measurement of short-term changes in heart rate and in plasma concentrations of cortisol and catecholamine in a small marsupial

Using a chronically placed jugular catheter and a silver electrode, it was possible to monitor short-term changes in the plasma concentration of cortisol and catecholamine in the marsupial sugar glider (Petaurus breviceps) and to monitor both heart and respiration rates. Males judged to be low in the social hierarchy of a particular group were exposed to the whole-body odor of a dominant male from the same social group, a foreign dominant male, or a castrate male. While there was no evidence of a change in any of the physiological parameters when a male was exposed to either a castrate male or a female, a rapid increase occurred in heart rate and plasma concentrations of cortisol, glucose and catecholamine when the donor was a dominant male from the same or a different social group.     

Effects of catalyst and vehicle in coal liquefaction

Experiments have been carried out, using a semi-batch reactor equipped with a consecutive sampling device, to clarify the effects of catalysts and vehicles in the coal liquefaction process. The results show that a vehicle has a significant effect during preheating, unlike a catalyst which is not effective at this stage. A catalyst is more effective in promoting liquefaction under reaction conditions of 450°C and ≈ 20 MPa than is a vehicle. A vehicle higher in hydrogen donation increases the yield of oil even if a catalyst is present, providing a multiplier effect. In the development of a direct coal liquefaction process, therefore, selection of a vehicle is as important as that of a catalyst.     

Evaluating the performance of a cascade of two bioreactors

We investigate a reactor network consisting of two chemostats in series. Previous researchers have compared the performance of a two-reactor system against a single reactor having the same total residence time. In this paper, we suggest that it is more natural to compare the performance of a cascade against the optimal performance a single-reactor system having the same, or smaller, residence time.We consider a biological system in which the growth rate is given by a Monod expression with a variable yield coefficient. We find that it is possible for this model to obtain a significant increase in performance by using a two-reactor system. However for the two-reactor system the performance enhancements are achieved when the system reaches a time-invariant steady-state rather than under conditions which produce self-generated oscillations, which was the focus of interest of earlier researchers.     

A next-generation wide color gamut WLED with improved spectral performance in phosphor composite functional solid

As is well known, a way to obtain a high color resolution and saturation of a liquid crystal display and thereby obtain a higher visual accuracy and comfort in the coming 5G era remains an urgent challenge. In the present study, a new type of phosphor composite material doped with Ln³⁺ ions provides a promising alternative to the color filters used in White light-emitting diodes (WLEDs), achieving a better performance regarding the realization of a wider color gamut. The advantages of this composite material are illustrated through an abundant phase and morphology analysis along with a discussion regarding the X-ray photoelectron spectroscopy of the valence bond of Ce ions, which maintain the luminescence properties of the phosphor while providing a stable and solid amorphous environment. An improved spectral performance was obtained through color filtering at 580 nm along with the regulating effects of red, green, and blue emissions according to the doped Ln³⁺ ions. Notably, we fabricated a high-performance WLED based on a Ln³⁺-doped PiG with a correlated color temperature of 5037 K, color rendering index of 72.8, and high color gamut of 91.97%, providing a new choice for the development of luminescence materials with a high color resolution and saturation.     

Colors of some small figures on colored grounds

Examination of the receptive field structure of the retina suggested looking at small graphic figures of special forms. The luminance distribution called the “Mexican hat function” was approximated by a black dot with a small white dot at its center, called a “tip,” and the inverse function was approximated by a white dot with a small black dot at its center, called a “pit.” Such figures were given the generic name “tippit.” On a dark‐blue ground, tips looked yellow, and on a bright‐yellow ground, pits looked blue. Similarly, a black line with a white center, on a blue ground, and a white line with a black center, on a yellow ground, elicited these effects. On yellow and blue grounds, simple, small colored dots looked more like the color of the ground than when seen as large spots on a neutral gray ground, an effect here called “microspreading.” This effect may be attributable to scattering and blurring, but these processes do not account for the tippit effects. The visual system exaggerates contrast between a large spot and ground, and diminishes contrast between a small dot and ground, but exhibits neither effect on a figure of some intermediate size. Chromatic pit lines exhibit effects obeying laws of additive mixture. It appears that perceptions of these effects are normally repressed. No causal link was sought or established between receptive field theory and the observed effects. © 2003 Wiley Periodicals, Inc. Col Res Appl, 28, 242–250, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10159     

Effect of the mechanical failure of catalyst pellets on the pressure drop of a reactor

The effect of the mechanical failure of catalyst pellets on the pressure drop across a laboratory-scale catalyst packing has been examined by experiment. Results reveal that, along with the mechanical failure of the pellets, there exists a point of maximum curvature around which the slope of pressure drop increases rapidly. This rapid increase is attributed to a mutation of the packing structure, occurring as the amount of failed pellets reaches a certain critical value. The secondary breakage of the pellets contributes much to the mutation of the packing and to the pressure drop. It has been observed that a trilobite catalyst is more susceptible to a mechanical stress than a cylindrical catalyst, and that a catalyst with a smaller diameter is much easier to result in an increase in the pressure drop. The measurement of the pressure drop across a laboratory-scale catalyst packing as the failure of pellets under a mechanical stress has a satisfactory reproducibility, and has a close meaning to the mechanical reliability of a fixed bed converter, and hence is recommended as a method for catalyst assessment. The multi-scale and multi-disciplinary nature of catalyst mechanical reliability is also discussed.     

Effect of novel benzoxazine reactive diluent on processability and thermomechanical characteristics of bi‐functional polybenzoxazine

Effects of a monofunctional benzoxazine diluent (Ph‐a) on properties of a bifunctional benzoxazine resin (BA‐a) have been investigated. The BA‐a/Ph‐a mixtures are miscible in nature rendering the properties highly dependent on their compositions. The viscosity of the BA‐a resin can be reduced to one third using only about 10% by weight the Ph‐a diluent. The addition of the Ph‐a resin into the BA‐a resin can also lower the liquefying temperature of the resin mixtures whereas the gel point is marginally decreased. The gel point, which depends on the BA‐a/Ph‐a mixtures and the cure temperature, was determined by the frequency independence of loss tangent in the vicinity of the sol‐gel transition. The relaxation exponent values of the copolymer were found to be 0.24–0.55, which is dependent on the cure temperature. Gel time of the BA‐a/Ph‐a systems decreases with increasing temperature according to an Arrhenius relation with activation energy of 60.6 ± 1.5 kJ/mol. Flexural moduli of the BA‐a/Ph‐a polymers also increase with the Ph‐a mass fraction, however, with the sacrifice of their flexural strength and glass‐transition temperature. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007