中、小型水溶液全循环法尿素装置特大安全事故隐患和有效防范(上)

尿素装置工艺过程存在着爆炸三要素,发生过多次特大爆炸事故,损失惨重,文中详细地分析了事故隐患范围和原因以及现有防范措施的使用局限性,作者提出的脱H2工艺新技术是从源头上有效地防范爆炸事故的发生,是“安全生产”和“放心操作”的有力保障。     

生产管道火灾扑救对策

生产管道同生产设备一样是生产装置中不可缺少的组成部分,起着把不同工艺功能的设备连接在一起的作用,以完成特定的工艺过程,在某些情况下,管道本身也同生产设备一样能完成某些生产过程,即“管道化生产”。生产管道布置纵横交错,管道种类繁多,被输送介质的理化性质多样,管道系统接点多,火灾爆炸事故发生率高。管道发生破裂爆炸事故,容易沿着管道系统扩展蔓延,使事故迅速扩大。研究生产管道火灾爆炸事故的类型,预防和控制火灾爆炸事故发生,是实现安全生产的一项重要工作。     

基于ALOHA软件对苯乙烯储罐泄露事故的后果分析

苯乙烯是一种危险的合成高分子材料的重要原料,其储罐发生泄漏会导致火灾、爆炸和人员中毒事故,采用ALOHA软件对储罐泄露后果进行模拟,定量得出了苯乙烯储罐泄露导致火灾、爆炸、中毒事故后果的危害范围。根据对储罐工艺过程风险分析的结果从预防事故发生的可能性及控制事故后果的严重程度两个方面,提出工艺过程风险控制措施。     

化工过程危险与可操作性及爆炸事故分析技术

介绍了化工生产开、停车过程人工误操作危险与可操作性分析系统（MO-HAZOP）、基于层次分析法的计算机辅助HAZOP分析方法和化工过程爆炸事故分析软件,系统地从物料、设备、工艺、人为因素和外部环境等方面对化工过程中潜在危险进行全面的分析。提出以发生概率值大小为依据对所有的危险路径进行排序,找出最容易发生的潜在危险路径。在分析的完备性的同时,增强了防范措施的针对性和可操作性。将导致爆炸事故的原因分为五类46种,对防范类似事故发生具有指导性意义。以某双苯厂硝基苯初馏塔分离工艺为例,阐述了防范控制人工误操作及爆炸事故分析技术的应用。分析结果表明,应用此技术,采用预防控制措施是可以防爆炸事故于未然的。     

隔膜法电解生产中的事故分析

电解是氯碱生产的关键,一巨发生事故,使导致全厂停产。国内氯碱厂1980年以前电解槽系统爆炸事故就有十多次,近年也有发生。严重者造成停产数十天,经济损失数十万元,甚至造成人身伤亡,如果把三氯化氮引起液氯钢瓶爆炸事故看做氯碱生产中第一大危险”,那么,电解槽系统爆炸事故就可以称为“第二大危险”。因此,不得不引起高度重     

基于HFACS-PE的典型危险化学品爆炸事故分析

结合危险化学品企业事故特点,对人因分析与分类系统(HFACS)框架的适用性进行了修正,构建了适用于分析危险化学品企业事故的HFACS-PE框架。利用该模型对宜宾恒达“7.12”爆炸着火事故的致灾因素进行分析发现,甲苯蒸气是事故发生的主要危险源。使用Phast 8.2对甲苯灾难性破裂产生的爆炸及火灾参数进行计算,发生事故模拟结果与现场情况基本吻合。结果表明,HFACS-PE框架模型对于识别每个事故过程中的主要参数,预防和减轻爆炸具有重要的指导意义。     

抓好奥运会后的安全生产

奥运结束后的近一段时间内,我国安全生产事故频发,出现了几起重大的安全生产事故,例如广维化工“8·26”爆炸事故,鑫鑫花炮厂“8·30”爆炸事故,上海浦东新区农药厂农药泄漏事故等,这些事故伤亡人数众多,影响甚大,引起了国人的关注。除此之外,我们还应注意到：奥运结束后,我国危险品运输事故增多,几乎每周都会发生危险品运输事故,甚至一天内发生多起危险品运输事故。     

提高炸药安全性和生存能力的途径

在最近二十年中,美国在处理、运输、贮存和使用弹药时,发生了许多爆炸事故,如企业号及Forestal号航空母舰上的爆炸事故,加里福尼亚的Roseuille火灾引起的爆炸,在战斗中发生的膛炸及坦克等的弹药箱被燃烧而引起的爆炸及殉爆等。由于发生了许多爆炸事故,再加上携带弹药的作战机器的价格日益昂贵,这就使得美国特别关注弹药的安全性和生存能力,因而提出今后着重发展“不易被损坏的弹药”,即LOVA(Low Vulnerability Ammu-nition)。     

江西强力推进化工企业改造危险工艺

日前，江西省在乐平市召开旺顺化工“6·15”爆炸事故警示暨危险工艺改造工作推进会，以事故警示强力推进化工企业改造危险工艺工作。     

溶解乙炔站的防火、防爆设计

分析了溶解乙炔站火灾、爆炸的原因。根据“以防为主，以消力辅”的原则，在建筑设计中采取了一系列措施，以预防火灾、爆炸事故的发生，或使事故的损失和危害降至最低。     

Catalytic removal of NOx from total energy installation flue-gases: process design and development

The flue-gases from total energy installations can be used for CO₂ fertilization in greenhouses. However, the gases contain too much toxic chemicals to be led into the greenhouses untreated. At Delft University of Technology a process has been developed for the removal of these toxins. This so called ‘Delft NO_x/urea process’ has been tested successfully downstream of a natural gas fired engine. Our group has described that the process could be well used for so called lean-bum engines. However, for non-lean-burn engines, which have a very high NO_x output (1500 ppm), the required NO_x conversion was not reached. Which was caused by high NO_x concentration. Hence, the process should be optimized further for this purpose. Especially, the decomposition of urea should be given more attention. This paper focuses on this aspect. The decomposition has been investigated both theoretically and experimentally.     

Effect of amounts and sequence of additions of urea and water on hydrolysis of surface-applied granular urea in unsaturated soils

The hydrolysis of surface-applied granular urea ( 15 mg of urea/particle) in 14 unsaturated soils as influenced by the amounts and the sequence of additions of urea and water and studied using open and covered soil column systems was in the following order: well-mixed surface-applied surface-applied surface-applied urea, granular urea, granular urea, granular urea, water added > water added > water added water added before, after, before, before, no drying no drying no drying drying The retarded hydrolysis' of surface-applied granular urea is attributed to retarded soil urease activity. Under the nondrying and drying conditions, the positive effect of increasing amounts of added water on the hydrolysis was less apparent when water was added 24–48 hours before than when it was added immediately after surface application of granular urea. When an increasing number of urea granules were evenly placed on a finite surface of unsaturated soil, the rate of urea application (quantity factor) increased but the percentage of urea hydrolyzed remained practically unchanged. These results suggest that it is necessary to consider effective urea concentration and effective urease activity for adequate understanding of in situ hydrolysis of broadcast fertilizer urea in unsaturated soil.     

Catalytic removal of NOx from total energy installation flue-gases for carbon dioxide fertilization in greenhouses

A catalytic process, based on urea as a reactant to remove NO_x from the exhaust gases of total energy installations driven by gas engines has been developed. A prototype has been successfully tested using a commercial gas engine.     

Voltammetric behaviour of iron in cement Part IV: Effect of acetate and urea additions

The effects of acetate and urea on the cyclic voltammetric behaviour of iron in cured cement paste were investigated. The voltammetric results indicate that sodium acetate and urea do not cause depassivation of iron in cement. The addition of 0.2 M of either sodium acetate or urea prevents depassivation of iron in cement exposed to 0.1 M sodium chloride upon potential cycling. However, the addition of even relatively high concentrations of sodium acetate or urea (e.g. 1.0 M), cannot prevent depassivation by 0.2 M sodium chloride upon potential cycling. The voltammetric results also indicate that sodium acetate, urea, and calcium magnesium acetate (CMA) are only marginally effective as corrosion inhibitors for reinforced concrete, compared with an inhibitor of known effectiveness, such as sodium nitrite. Thus, while acetates and urea may well be non-corrosive deicers when used by themselves, large amounts of sodium chloride should not be mixed with acetates or urea as a cost-reducing measure.     

两段法变压吸附脱碳装置应用总结

介绍了两段法变压吸附（PSA）脱碳装置生产应用情况。经过近5年的长期运行,证明两段法变压吸附脱碳装置具有操作稳定、生产成本低的特点,完全满足了尿素生产的需要。     

钠添加剂对介质阻挡-电晕放电耦合法尿素脱除NO的影响

利用自主设计的介质阻挡-电晕放电耦合装置进行脱除NO的实验研究,在N₂/O₂/NO体系中,考察加入不同钠添加剂（Na₂CO₃、NaOH、CH₃COONa）对尿素脱除NO的影响,同时探讨其在脱除NO过程中的作用机理。结果表明：在研究范围内,仅添加尿素时,NO脱除率随尿素含量的增加而增大,当输入电流为0.83A,尿素分解产生氨气的体积分数为0.3%时,NO脱除率为64.23%,此时体系中有CO生成且随尿素含量的增加而增加;少量钠添加剂的加入可显著提高NO脱除率,且脱除率随钠添加剂含量的增加而增大,此时CO生成量得到有效抑制。在加入量相同的条件下,各种钠添加剂对尿素脱除NO均有促进作用,促进作用大小依次为：NaOH > Na₂CO₃ > CH₃COONa,当加入氢氧化钠与尿素质量比为10∶10时,输入电流仅为0.83A时,脱除率可达90.71%;电流为5A,脱除率达95.71%,此时体系中几乎无CO生成。     

An evaluation of urea-rubber matrices as slow-release fertilizers

The viability of a urea-rubber matrix (URM) as a slow-release nitrogen fertilizer was assessed by field trials and incubation studies. Encapsulation of urea in the rubber matrix apparently prevented the inhibition of seed germination experienced at high temperatures (> 20°C) following high urea applications. The release of urea from URM increased with temperature and was well described by a diffusion model which allowed for the temperature-dependence of both the diffusion coefficient in water and the saturated concentration of urea. Initial results suggest that the effect of varying the size of URM cuboids on both their release characteristics in moist soil and N-supply to plants is also reasonably well predicted by the diffusion model. In a ryegrass field trial over 24 weeks, the URM gave higher dry matter yields than either prilled urea or (NH₄)₂SO₄ (following a single application at sowing) through efficient matching of nitrogen supply and crop demand.     

700t/d尿素成品流化床降温除尘装置运行小结

因产能扩张达700t/d,φ12m尿素造粒塔超负荷运行.选用后置式流化床对成品尿素进行降温除尘.装置投运后,除尘降温效果较好.     

Reaction of NO with urea supported on activated carbons

Reaction of NO in air with urea supported on activated carbons (AC) was examined in the range of 100–1000 ppm NO at room temperature to establish a basic scheme for its reduction in open atmosphere. NO in atmosphere containing O₂ was found to be selectively reduced with urea supported on AC at the W/F of 2.5×10⁻³ to 1.5×10⁻³ ACF g min/ml and its reduction continued until the complete consumption of urea. The reduction of NO with urea supported on AC appears to proceed through the following steps.

NO₂+NO+(NH₂)₂CO→2N₂+CO₂+H₂O

Combining (1) and (2) steps results in the followed reaction equation.

Since (1) is rate determining, high NO oxidation activity is essential for AC to be active for the reaction. At the same time, activation of urea by AC is also necessary to reduce NO₂. The present scheme for NO reduction with urea on the AC is very effective to remove NO_x in the open atmosphere under ambient conditions.