同时发生初次和二次成核且为聚结控制的沉淀过程多定态及稳定性分析

The possibility of multiplicity in an isothermal continuous mixed suspension-mixed product removal crystallizer is explored using the bifurcation theory.A process involving agglomeration controlled precipitation is considered in which secondary nucleation occurs simultaneously with primary nucleation.The determinant equations for the existence of multiple steady states are developed and the multiplicity boundaries dependent on the physical and kinetic properties and operational parameters of the process are obtained by resolving these determinant equations.The number of steady states in the precipitator for various multiplicity regions is determined and the linear stability of these steady states is analyzed by using the Routh criterion.     

Anaerobic biodegradation of RDX and HMX with different co-substrates☆

Simulated wastewater of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) was treated under anaerobic conditions with co-substrates such as ammonium chloride, dex-trose, sodium acetic, sodium nitrate and sulfate. The results showed that with nitrogen compounds such as ammonium chloride added as co-substrate, no significant change was observed, indicating that the molar ratio of N/C for RDX and HMX is sufficient for biodegradation. With the addition of dextrose and acetate to the system, biodegradation efficiency was enhanced greatly. For example, with dextrose as the co-substrate, degradation efficiency of 99.1%and 98.5%was achieved for RDX and HMX, respectively, after treatment for 7 days. When so-dium acetic was used as the co-substrate, the enhancement of degradation percentage was similar, but was not as high as that with dextrose, indicating the selectivity of RDX and HMX to co-substrate during anaerobic degrada-tion. With sodium nitrate as the co-substrate, the degradation efficiency of RDX or HMX decreased with the increase of salt concentration. Sodium sulfate has no significant effect on the biodegradation of RDX and HMX. A wel-selected co-substrate should be employed in applications for degradation of RDX and HMX wastewaters.     

Effects of Additives on Properties of Unburned MgO—Al2O3 Refractory

The influences of four kinds of additives added into the matrix of MgO-Al2O3 unbuned products were investigated,The results show that samples with proper MgO/Al2O3 ration and proper addition of Cr2O3(2%- 4%) have good thermal shock resistance and slag corrosion resistance as well,XRD and SEM determination results indicate that a kind of compound spinel(Mg,Al, Cr) O4 was formed and the microstucture of the samples are denser.     

基于Ni/Al2O3催化的异丁烯二聚反应精馏过程的动力学研究（英文）

Isooctane is a promising gasoline additive that could be produced by dimerization of isobutene (IB) with subse-quent hydrogenation. In this work, the dimerization of IB has been carried out in a batch reactor over a temper-ature range of 338–383 K in the presence of laboratory prepared Ni/Al2O3 as a catalyst and n-pentane as solvent. The influence of various parameters such as temperature, catalyst loading and initial concentration of IB was examined. A Langmuir–Hinshelwood kinetic model of IB dimerization was established and the parameters were estimated on the basis of the measured data. The feasibility of oligomerization of IB based on the reactive distil ation was simulated in ASPEN PLUS using the kinetics developed. The simulation results showed that the catalyst of Ni/Al2O3 had higher selectivity to diisobutene (DIB) and slightly lower conversion of IB than ion exchange resin in the absence of polar substances.     

Development of High Quality Magnesite—Chrome Bricks for Secondary Steelmaking Furnaces

This paper describes developments of high quality magnesite-chrome bricks used for secondary steelmaking furnaces,mainly including direct-bond-ed magnesite-chrome brick,fully synthesized(co-clinker) magnesite-chrome brick,semi-rebonded magnesite-chrome brick and fused grain rebonded magnesite-chroe brick,Investigations have also been conducted on the effects of various chromites on the properties of the direct bonded magnesite-chrome brick,effects of different sesquioxides (CrO3,Al3O3,Fe2O3) on the properties of the fully synthe-sized(co-clinker) magnesite-hrome brick and ef-fects of ZrO2,Cr-Fe alloy,ultra-fine powders on the properties of the fused grain rebonded brick and the semi-rebonded magnesite-chrome brick ,Applica-tions of the bricks in various secondary steelmaking furnaces have been briefly introduced as well.     

Service Results and Analysis of Fully Co—clinkered Magnesite—Chrome Brick in Slagline Area of VOD Vessel

Operating condition and service results of several tested bricks in slagline area of the VOD vessel are described,It has been shown that the fully co-clinkered magnesite chrome brikc is superior,followed by two-stage calcined magnesite-dolominte brick,preracted magnesite-chrome brick and one-stage calcined moagnesite-dolomite brick. Chemical and petrologial examination were carried out by conventional analysis and optical microscope respectively,The reason of damage of the tested bricks are discussed and described as follows:(1) MgO in brick is erosed and dissolved by slag to destroy structure of the direct bond;(2)slag penctrating into the brick and then reacting with it to from various belts leading to spalling;(3)reducing action of reucing agents;(4) vaporiztion of some composition in the brick at high temperature under vacuum causes reducing weight and increasing porosity and (5) serious machanic abrasion.Therefore,Some opinions on increasing lining life of VOD vessels are suggested.     

RECENT ADVANCES IN HYDRATE-BASED TECHNOLOGIES FOR NATURAL GAS STORAGE——A REVIEW

Interest in the possibility of storing and transporting natural gas in the form of clathrate hydrates has been increasing in recent years, particularly in some gas-importing and exporting countries. The technologies necessary for realizing this possibility may be classified into those relevant to the four serial processes——(a) the formation of a hydrate, (b) the processing (dewatering, pelletizing, etc.) of the formed hydrate, (c) the storage and transportation of the processed hydrate, and (d) the regasification (dissociation) of the hydrate. The technological development of any of these processes is still at an early stage. For hydrate formation, for example, various rival operations have been proposed. However, many of them have never been subjected to actual tests for practical use. More efforts are required for examining the different hydrate-formation technologies and for rating them by comparison. The general design of the processing of the formed hydrate inevitably depends on both the hydrate-ormation process and the storage/transportation process, hence it has a wide variability. The major uncertainty in the storage-process design lies in the as-yet unclarified utility of the "self-preservation" effect of the naturalgas hydrates. The process design as well as the relevant cost evaluation should strongly depend on whether the hydrates are well preserved at atmospheric pressure in large-scale storage facilities. The regasification process has been studied less extensively than the former processes. The state of the art of the technological development in each of the serial processes is reviewed, placing emphasis on the hydrate formation process.     

纯磷脂单分子膜压缩过程中磷脂分子的构象和取向(英文)

On the basis of energy conservation law and surface pressure isotherm, the conformation energy changes of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG) in pure phospholipid monolayer at the air/water interface during compression are derived. The optimized conformations of phospholipids at absolute freedom state are simulated by Gaussian 98 software. Based on following assumptions: (1)the conformation energy change is mainly caused by the rotation of one special bond; (2)the atoms of glycerol near the water surface are active; (3)the rotation is motivated by hydrogen-bond action; (4)the rotation of bond is inertial, one simplified track of conformational change is suggested and the conformations of DPPC and DPPG at different states are determined by the plots of conformation energy change vs. dihedral angle. The thickness of the simulated phospholipid monolayer is consistent with published experimental result. According to molecular areas at different states, the molecular orientations in the compressing process are also developed.     

Mesoporous titanium-aluminosilicate as an efficient catalyst for selective oxidation of cyclohexene at mild reaction conditions

Mesoporous titanium containing alumino-silicate materials with various titanium/silicon(Ti/Si) ratio(AlSi-Ti(n); n = Ti/Si mole ratio) have been successfully synthesized by a novel single-step sodium(Na)-free method, for the first time. The obtained characterization results of the prepared materials reveal that in-situ addition of Ti into AlSi shows ordered mesoporous structure along with uniformly dispersed Ti species in +4 and +3 oxidation states suitable for selective oxidation of allylic C—H...     

Effect of salts and their interaction with ingenious surfactants on the interfacial tension of crude oil/ionic solution

Understanding the roles of asphaltene and resin as natural surfactants existed in crude oil can enlighten contradicting reported results regarding interfacial tension(IFT) of crude oil/aqueous solution as a function of salinity and ion type. In this way, this study is aimed to investigate the effect of these natural surface active agents on IFT of with special focus on SO_4~(2-)anion and Mg~(2+)cation. Two different synthetic oil solutions of 8 wt% of the extracted asphaltene and resin dissolved in toluene are prepared, and then IFT values are measured. After that,the obtained results are compared with the IFT of intact crude oil in contact with the same saline solutions examined in the previous stage. The obtained results showed a synergistic effect of Na_2SO_4+ MgCl_2 solution unlike the MgSO_4+ MgCl_2 and CaSO_4+ MgCl_2 solutions on IFT reduction of resin at MgCl_2 concentration of 15000 mg·kg~(-1). In summary, it is found that the affinity of asphaltene molecules towards the interface of oleic phase/ionic solution leads to higher IFT variation.     

Characterization of Aluminum Nanopowder Compositions

The thermal behaviour of two different Al nanopowders and a micron‐sized Al powder was studied using DSC, simultaneous TG‐DTA, and accelerating rate calorimetry (ARC). The results show that the reactivity of Al powder increases as the particle size decreases. The thermal stability of the smaller Al nanopowder (Als) in water and in a humid atmosphere was determined using ARC and TG‐DTA, respectively. Atomic Absorption Spectrometry (AAS), X‐Ray Photoelectron Spectrometry (XPS) and Auger Electron Spectrometry (AES) were used to characterize the surface chemistry of Alex. The outgassing behaviour for mixtures of RDX and the various Al powders was investigated using TG‐DTA‐FTIR‐MS. Evolution of NO₂ and N₂O from a chemical interaction between Al nanopowders and RDX was observed. The effect of Als and Alex on the thermal stability of TNT, RDX, Comp B, and AP was determined using ARC. Addition of Als significantly lowered the onset temperature for TNT and RDX decomposition. Electrostatic discharge (ESD) sensitivities of Al nanopowders and their mixtures with TNT, Comp B, RDX and AP were determined. The results show that the AP/Als mixture is very sensitive to ESD. Standard dust explosibility tests demonstrated that Alex is highly explosible.     

HTPB/Al/AP/RDX复合推进剂组元之间相互作用研究

为了探索HTPB/Al/AP/RDX复合推进剂组元之间的相互作用,用DSC和TG-DTG方法以及分解反应动力学计算研究了递增组元的4个混合体系(包括HTPB黏合剂体系、HTPB/Al、HTPB/Al/AP和HTPB/Al/AP/RDX推进剂体系)中各组元之间的相互作用。结果表明,DTG峰温以及反应速率常数k可以表征各组元之间的相互作用,其DSC和TG过程可以分为3个阶段;除Al外,各组元之间存在相互作用,各阶段的质量损失测定值与按组分含量计算的加合值吻合得相当好,表明各组元并没有明显的跨阶段分解;AP与HTPB黏合剂的分解温度区间接近或部分重叠,在HTPB/Al/AP和HTPB/Al/AP/RDX的混合体系中发生了强烈氧化还原作用:四组元体系中RDX在200℃及220℃的速率常数k分别为1.53和6.81s-1,均大于单质RDX在同一温度下的速率常数1.33×10-6和1.06×10-5s-1,说明AP可以加速RDX的分解,但RDX对AP或(AP+HTPB)分解的影响呈现复杂的情况,由于HTPB/Al/AP和HTPB/Al/AP/RDX两体系中AP与HTPB的共同分解过程中存在“等动力学点”(308.0℃),温度低于此点时(AP+HTPB)分解速率常数k因RDX存在而下降,而当温度高于此点时则该k值因RDX存在而增大。通过RDX分解机理解释了存在这种现象的原因。     

老化对TNT基熔铸炸药性能的影响

为了研究老化对炸药性能的影响，对自然贮存的3种熔铸炸药TNT／RDX、TNT／RDX／Al和 TNT／HMX／Al进行了加速老化试验。通过扫描电镜、真空安定性试验研究了老化前后3种炸药的微观形貌和安全性能，并测试了老化前后3种炸药的感度和爆速。结果表明，老化后炸药颜色变深，体积膨胀，质量变轻。样品的放气量小于2 mL／g ，热感度变化也较小。机械感度的变化与炸药组分和老化方式有关。TNT／RDX的爆速随着贮存时间的增加而降低，与整体加速老化情况一致，TNT／RDX／Al和 TNT／HMX／Al的爆热随贮存时间的增加变化趋势相反，说明两者老化机理可能不同。     

Applying modified hyperbranched polyester in hydroxyl‐terminated polyether/ammonium perchlorate/aluminium/cyclotrimethylenetrinitramine (HTPE/AP/Al/RDX) composite solid propellant

Composite solid propellants demand fine and stable mechanical properties, creep resistance and stress relaxation performance during their long storage and usage time. In this study, modified hyperbranched polyester (MHBPE) was prepared and introduced into HTPE/AP/Al/RDX (HTPE, hydroxyl‐terminated polyether; AP, ammonium perchlorate; RDX, cyclotrimethylenetrinitramine) solid propellant as an effective additive. The static tensile and dynamic mechanical properties of this propellant before and after the introduction of MHBPE were evaluated. The elevated interfacial interaction by using MHBPE between the binder and RDX fillers improved the toughness and elasticity of the propellant. The enhancement mechanisms were also confirmed by the influence on the fracture surface morphology of the binder which was investigated by SEM. In addition, some influence on the dynamic mechanical properties of HTPE/AP/Al/RDX propellant caused by MHBPE was investigated by dynamic mechanical analysis. The creep behaviors of the HTPE/AP/Al/RDX propellants with and without MHBPE were also investigated at different stresses and temperatures. Reduced creep strain rate and strain were obtained for the modified propellant, implying enhanced creep resistance performance. The creep properties were quantitatively evaluated using a six‐element model and the long‐term creep performance of the propellant was predicted using the time–temperature superposition principle. A creep behavior of nearly 10⁶ s at 30 °C could be acquired in a short‐term experiment (800 s) at 30–70 °C. Moreover, the stress relaxation investigation of the propellants with and without MHBPE at ?40 °C, 20 °C and 70 °C suggested that MHBPE/HTPE/AP/Al/RDX propellant possessed better response ability to deformation. Thus, the application of MHBPE provides an efficient route of reinforcement to enhance the creep resistance and stress relaxation properties. © 2020 Society of Chemical Industry     

Research on the Combustion Properties of Propellants with Low Content of Nano Metal Powders

A comparison of various experimental results for combustionrelated properties evaluation, including burning rates, deflagration heat, flame structures and thermal decomposition properties, of AP/RDX/Al/HTPB composite propellants containing nano metal powders is presented. The thermal behavior of n‐Al (nano grain size aluminum) and g‐Al (general grain size aluminum i.e., 10 μm) heated in air was also investigated by thermogravimetry. The burning rates results indicate that the usage of bimodal aluminum distribution with the ratio around 4 : 1 of n‐Al to g‐Al or the addition of 2% nano nickel powders (n‐Ni) will improve the burning behavior of the propellant, while the usage of grading aluminum powders with the ratio 1 : 1 of n‐Al to g‐Al will impair the combustion of the propellant. Results show that n‐Al and n‐Ni both have a lower heating capacity, lower ignition threshold and shorter combustion time than g‐Al. In addition n‐Al is inclined to burn in single particle form. And the thermal analysis results show that n‐Ni can catalyze the thermal decomposition of AP in the propellant. The results also confirm the high reactivity of n‐Al, which will lead to a lower reaction temperature and rather higher degree of reaction ratio as compared with g‐Al in air. All these factors will influence the combustion of propellants.     

含硝胺和铝粉的少烟改性双基推进剂表面和界面性能

研究了不同含氮量的硝化棉(NC)和不同粒度填料(Al、RDX和HMX)的表面性能,NC与填料之间的界面性能,以及表面和界面性能对含硝胺和铝粉的少烟改性双基推进剂力学性能的影响.结果表明,随着RDX、HMX以及A1粉粒度的减小,其表面张力逐渐增大,RDX、HMX与NC之间的界面张力随着RDX和HMX粒度或硝化棉含氮量的减...     

Partial Reparametrization of the BKW Equation of State for DNAN‐Based Melt‐Cast Explosives

DNAN‐based melt‐cast explosives are a type of new, insensitive munitions (IM) explosives. Quickly determining munitions’ explosive properties is extremely important during the formulation design stage. The aim of this study was to partially reparameterize BKW‐EOS (only β and κ were reparameterized on the basis of the parameters (α , β , κ , and θ ) of classical BKW‐RDX set and BKW‐TNT set) to more accurately predict the properties of DNAN‐based melt‐cast explosives. A new set of parameters β and κ was obtained (β =0.19, κ =9.81) according to measured detonation velocity and detonation pressure for ideal DNAN‐based melt‐cast formulations (DNAN/RDX and DNAN/HMX). For non‐ideal DNAN‐based melt‐cast formulations (DNAN/RDX/Al and DNAN/HMX/Al), aluminum oxidation degree was first determined according to the measured detonation heat; then, another new set of parameters β and κ was obtained in the same way as the ideal formulations (β =0.24, κ =8.5). The predicted detonation properties with BKW reparametrization for DNAN‐based melt‐cast explosives agreed with the measured data.     

超声空化-表面活性剂水溶法提取RDX/Al/AP/HTPB炸药中的AP

为了对RDX/Al/AP/HTPB炸药的有效成分进行分离回收,研究了以超声空化-表面活性剂水溶法提取RDX/Al/AP/HTPB炸药中高氯酸铵(AP)的分离工艺,探讨了各工艺参数对AP提取率的影响。结果表明,表面活性剂浓度、提取时间和超声频率是影响AP提取率的主要因素,表面活性剂种类为次要因素,料液质量比和提取次数对AP提取率的影响很小。最佳工艺条件为:室温,提取时间40min,料液质量比1∶3,提取次数1次,超声功率3.0kW,表面活性剂为吐温80(质量分数2.0%)。     

RDX/Al/Fe2O3纳米复合材料的制备

以FeCl3·6H2O和RDX的DMF溶液为前驱体,依次加入环氧丙烷和纳米Al粉,通过Fe2O3由溶胶-凝胶的相变作用,使纳米Al粉和RDx进入Fe2O3凝胶网状结构中,采用超临界干燥法制备出纳米RDX/Al/Fe2O3复合材料,用扫描电镜对其进行了表征.结果表明,随着FeCl3·6H2O摩尔浓度的增加,凝胶时间逐渐缩...     

超细RDX/Al混合炸药的制备及性能

以超细RDX为主体炸药,通过添加Al粉,干法工艺制备出超细RDX/Al混合炸药;对制得的样品进行了撞击感度、摩擦感度测试。实验结果表明,相对超细RDX,超细RDX/Al混合炸药的撞击感度和摩擦感度有一定程度的降低。