Aspen Plus模拟计算在苯硝化HAZOP风险分析中的应用

为提高石油化工装置过程风险分析的准确性,建立一种将过程模拟融入危险与可操作性分析(HAZOP)的HAZOP-Aspen Plus定量风险分析方法。基于传统HAZOP分析结果,通过化工流程模拟软件Aspen Plus建立分析对象(苯硝化)的流程模型。利用灵敏度分析功能模拟过程参数对目标参数的影响,根据设备安全控制要求,获取过程操作参数的安全范围,实现HAZOP偏差定量化分析。将此方法应用于某公司硝基苯生产中硝化工段的风险分析中。结果表明,该方法可用来直观反映偏差对系统的影响,实现HAZOP偏差量化分析,进而提出有针对性的防护措施。

苯硝化工艺HAZOP分析的定量化研究

为提高危险化工工艺过程风险评估的准确性,通过工艺仿真模拟,研究工艺参数波动对生产装置安全性能的影响。以苯硝化工艺为例,采用危险与可操作性分析对该过程进行定性的风险评估;同时利用Aspen Plus建立苯硝化装置的模拟流程。结合HAZOP分析中偏差与模拟中硝化釜的流程变量之间的联系,以进料混酸的流量和1号硝化釜热负荷及出口温度为量化指标,观察混酸流量在正常操作点17.6 m3/h的±100%范围波动下1号硝化釜热负荷及出口温度的变化。研究结果表明,保持1号硝化釜温度为正常值,随着混酸流量的增大,硝化釜热负荷先增大后减小;保持硝化釜热负荷不变,随着混酸流量的增大,硝化釜温度先增大后减小。其中混酸流量值超过22.95 m3/h时,温度超过报警阈值60℃。

硫酸/硝酸摩尔比对苯硝化反应影响的实验研究

本文在内径0.15 m,高0.375 m,体积0.006 5 m3的无挡板玻璃反应器中对苯硝化反应过程进行了研究。研究结果表明：硝基苯在酸相中的溶解度与硫酸/硝酸摩尔比有直接关系。随着硫酸/硝酸摩尔比增大,硝基苯在酸相中的溶解度明显增大,表面张力逐渐减小。当硫酸/硝酸摩尔比为3.8~4.7时,1,3-二硝基苯的收率非常低。当硫酸/硝酸摩尔比大于5.3时,随摩尔比增大,1,3-二硝基苯在酸相中的浓度和收率迅速增加。随硫酸浓度增大,硝酸转化率明显增大。

苯硝化反应器放大设计

简要介绍了50kt.a硝基苯装置用混酸作硝化剂的苯硝化反应机理、反应特点,以及苯硝化反应器放大设计主要工艺参数的确定,及实现这些工艺条件必须采取的技术措施和控制手段,并对设计中存在的问题进行分析并提出改进建议。

硝化苯硝化甲苯酸洗比色高的原因及改进措施

本文分析比色高的原因,是轻苯带水和干点高,初馏操作等影响,并提出了改进措施。

苯一硝化传统锅式生产的安全保证

硝基苯是一种重要的有机合成中间体,在染料、医药、农药、香料等工业中具有重要用途。硝基苯是通过苯-硝化反应制成的,其反应式可以简单表示如下:

苯系硝化工艺危险性分析与安全设施设计方法初探

在化学工艺产品的生产过程中,很多危险的化学产品由于自身特有的性质,比如易燃易爆、带有一定的腐蚀性、并且很多的化学产品具有有毒的性质,所以会引发一些危险的事故,在这样的化工企业中是频发的。苯硝在其生产的过程中,本身具有很强的毒性,涉及到的危险物品种类是非常多的,因此,在苯硝的实际生产过程中,不管工厂规模的大小,对必须对其安全性进行合理有效的保证。所以在生产过程中,需要及时了解并认识到其危害性,合理有效的规避潜在的危险。所以需要及时对苯系硝化的整个过程中存在的危险因素进行深入地探析。

苯系硝化工艺危险性分析与安全设施设计研究

本文以一硝基苯系物生产为例,结合工业化生产实践,分析了苯系硝化工艺的危险点,并对照其危险特点,在连续化工艺、自动化设计基础、进料控制、安全仪表系统、紧急冷却系统、危险废物、精馏、设备防腐蚀、建筑等9个方面提出了安全设施设计要点,以期为苯系硝化工艺的工程设计提供参考。

硝基苯清洁生产催化剂及工艺的研究

从硝化剂、催化剂和工艺等方面阐述了用于清洁生产硝基苯的方法。讨论各种固体酸催化剂对苯硝化的催化活性、反应温度、苯与硝化剂物质的量比等工艺条件对硝基苯基本收率的影响。

硝基苯装置扩能改造开车小结

介绍了某苯硝化制硝基苯装置扩能改造后的开车过程,并对运行情况进行了分析和总结。改造后装置硝基苯年产量可达100 kt,产品质量均可达到(GB/T 9335—2009)中优等品要求,各项原料消耗均达设计指标,实现了扩能改造的目的。改造装置中多道工序采用了静态混合技术,具有一定的推广和借鉴意义。

Synthesis of N,N′-Bis(2-Nitro Benzodifuroxanyl)-1,3,5-Trinitro-2,6- Diaminobenzene

N, N’-bis (2-nitro benzodifuroxanyl)-1, 3, 5-trinitro-2, 6-diaminobenzene has been synthesized from 1, 3-dianimobenzene and trinitrotrichloro benzene. The molecular structure of this compound has been determined by elemental analysis. IR. ′HNMR, and M. S. spectroscopies.

Synthesis of N,N'-bis(2,4-dinitrobenzofuroxan)-3,5-dinitro-2,6-diaminopyridine

N,N'-bis(2,4-dinitrobenzofuroxan)-3,5-dinitro-2,6-diaminopy- ridine has been synthesized from 2,6-diaminopyridine and trinitrodich- lorobenzene.For this compound,the structure has been determined by ele- mental analysis,IR,HNMR and MS spectroscopy.

High selectivity to p-chloroaniline in the hydrogenation of p-chloronitrobenzene on Ni modified carbon nitride catalyst

A nanocomposite composed of Ni modified carbon nitride was synthesized and used in the hydro- genation of p-chloronitrobenzene. H/D exchange demonstrated that the hydrogen chemisorbed on the surface of this nanocomposite catalyst had a hydrogen atom density of 0.65/nm2. It was active for hydrogenation but its activity was inferior to the hydrogen adsorbed on a Ni/Al2O3 catalyst. Catalytic tests showed that this catalyst possessed a lower activity than Ni/AhO3 but the selectivity towards p-chloroaniline was above 99.9%. Even at high conversion, the catalyst maintained high selectivity, which was attributed to the unique surface property of the catalyst and the absence of a site for the adsorption ofp-chloronitrobenzene, which prevents the C-Cl bond from breaking.

Effects of the Supports on Activity of Supported Nickel Catalysts for Hydrogenation of m-Dinitrobenzene to m-Phenylenediamine

The hydrogenation of m-dinitrobenzene to m-phenylenediamine in liquid phase was studied with the nickel catalysts supported on SiO2, TiO2, γ-Al2O3, MgO and diatomite carders. Based on the experiments of X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, temperature-programmed reduction （TPR）, temperature-programmed desorption of hydrogen （H2-TPD） and activity evaluation, the physico-chemical and catalytic properties of the catalysts were investigated. Among the catalysts tested, the SiO2 supported nickel catalyst showed the highest activity and selectivity towards m-phenylenediamine, over which 97.3% m-dinitrobenzene conversion and 95.1% m-phenylenediamine yield were obtained at 373K under hydrogen pressure of 2.6MPa after reaction for 6 h when using ethanol as solvent. Although TiO2 and diatomite supported nickel catalysts also presented high activity, they had lower selectivity towards m-phenylenediamine. As for γ-Al2O3 and MgO supported catalysts were almost inactive for the object reaction. It was shown that both the activity and selectivity of the catalysts were strongly depended on the interaction between nickel and the support. The higher activities of Ni/SiO2, Ni/TiO2 and Ni/diatomite could be attributed to the weaker metal-support interaction, on which Ni species presented as crystallized Ni metal particles. On the other hand, there existed strong metal-support interaction in Ni/MgO and Ni γ-Al2O3, which causes these catalysts more difficult to be reduced and the availability of Ni active sites decreased, resulting in their low catalytic activity.

The Effect of Titania Structure on Ni/TiO_2 Catalysts for p-Nitrophenol Hydrogenation

The catalytic hydrogenation of p-nitrophenol to p-aminophenol was investigated over Ni/TiO2 catalysts prepared by a liquid-phase chemical reduction method. The catalysts were characterized by inductively coupled plasma (ICP), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS) and temperature-programmed reduction (TPR). Results show that the titania structure has favorable influence on physio-chemical and catalytic properties of Ni/TiO2 catalysts. Compared to commercial Raney nickel, the catalytic activity of Ni/TiO2 catalyst is much superior, irrespective of the titania structure. The catalytic activity of anatase titania supported nickel catalyst Ni/TiO2(A) is higher than that of rutile titania supported nickel catalyst Ni/TiO2(R), possibly because the reduction of nickel oxide to metallic nickel for Ni/TiO2(A) is easier than that for Ni/TiO2(R) at similar reaction conditions.

Degradation of Wastewater Containing Nitrobenzene by High Gravity-Ultrasonic/Ozonation/Electrolysis Technology

The integrated high gravity-ultrasonic/ozonation/electrolysis technology was applied in the pretreatment of wastewater containing nitrobenzene. The effect ofpH value, high gravity factor, liquid flow-rate and electric current density on removal of COD and nitrobenzene compounds was investigated. Experimental results have determined the optimal pro- cess regime involving a high gravity factor of 100, an electric current density of 20 mA/cm2, a liquid flow-rate of 100 L/h, and an initial liquid pH value of 11. After the wastewater had been treated for 180 rain, the degradation of nitrobenzene and COD reached 99% and 80%, respectively, with the biochemical coefficient （BOD/COD） equating to 0.64, and the subse- quent treatment of wastewater could be carried out by conventional biochemical means. Compared with traditional aeration- ozone contactors, a rotating packed bed with high mass transfer characteristics could be used to increase the ozonation treat- ment efficiency.

Kinetics of Ortho-nitrochlorobenzene Hydrogenation on Platinum/Carbon Catalyst

The kinetics of catalytic hydrogenation of ortho-nitrochlorobenzene to 2,2′-dichloroazoxybenzene on platinum/carbon catalyst is investigated in a slurry reactor with the temperature range of 313-343 K, and orthochloroaniline is formed as a byproduct. Models based on Rideal-Eley and Langmuir-Hinshelwood mechanism have been proposed based on the rate data and the kinetic regime. The former model can be used to fit the experimental data better. Reaction controlling steps are physical adsorption of hydrogen and adsorbed ortho-nitrochlorobenzene reacted on the surface of catalyst.

A Highly Efficient and Selective Water-Soluble Bimetallic Catalyst for Hydrogenation of Chloronitrobenzene to Chloroaniline

Selective hydrogenation of chloronitrobenzene(CNB) to chloroaniline(CAN) catalyzed by water-soluble Ru/Pt bimetallic catalyst in an aqueous-organic biphasic system was studied. It was found that the catalytic activity increased obviously due to the addition of platinum. Ru/Pt bimetallic catalysts exhibited a strong synergistic effect when the molar ratio of Pt was in the range of 5%—80%. Under the mild conditions including a temperature of 25 ℃, a hydrogen pressure of 1.0 MPa and a Pt molar ratio of 20%, the conversion of p-chloronitrobenzene(p-CNB) reached 99.9%, with the selectivity to p-chloroaniline(p-CAN) equating to 99.4%. The Ru/Pt catalyst also showed high activity and selectivity for the hydrogenation of other chloro- and dichloro-nitrobenzenes with different substituted positions. In addition, the catalyst can be recycled five times without significant loss of activity.

Isolation and characteristics of Arthrobacter sp.strain CW-1 for biodegradation of PAEs

Isolation of new bacterial strains and recognition of their metabolic activities are highly desirable for sustainability of natural ecosystems. Biodegradation of dimethyl phthalate （DMP） under anoxic conditions has been shown to occur as a series of sequential steps using strain CW-1 isolated from digested sludge of Sibao Wastewater Treatment Plant in Hangzhou, China. The microbial colony on LB medium was yellowish, 3-5 mm in diameter, convex in the center, and embedded in mucous externally. The individual cells of strain CW-1 are irregular rods, measuring （0.6-0.7）×（0.9-1.0） pm, V-shaped, with clubbed ends, Gram positive and without any filaments. 16S rDNA （ 1438 bp） sequence analysis showed that the strain was related to Arthrobacter sp. CW-1 and can degrade PAEs utilizing nitrate as electron acceptor, but cannot mineralize DMP completely. The degradation pathway was recommended as： dimethyl phthalate （DMP）→monomethyl phthalate （MMP）--,phthalic acid （PA）. DMP biodegradation was a first order reaction with degradation rate constant of 0.3033 d 1 and half-life 2.25 d. The DMP conversion to PA by CW-1 could be described by using sequential kinetic model.

HYDROGENATION OF NITROBENZENE TO FORM ANILINE IN LIQUID PHASE AT ATMOSPHERIC PRESSURE

Aromatic amine compounds and their derivatives are important intermediates of fine chemicals like dye and medicine. The former hydrogenation catalyst has many problems, such as environment pollution caused by old technology, strict reaction condition, complicated equipment, bad property of catalyst and so on. Holy [1] firstly reported the hydrogenation of nitrobenzene on modified polystyrene Pd catalyst. But how to improve the activity, selectivity and stability of the polymer supporter catalyst needs to studyfurther. We prepared a series of polymer supported catalysts by the methods of adsorption and mechanical mixting, selected a high active catalyst Pd-AH-1 by observing the hydrogenation of nitrobenzene.