氧气高炉多流体数值模拟与分析

为研究不同氧气高炉操作流程及操作参数对高炉内部过程产生的影响,预测氧气高炉流程各参数的变化规律,基于多流体理论、冶金传输原理、冶金反应动力学与热力学理论以及计算流体力学建立了普通高炉多流体模型,并在此基础上修改边界条件及内部相关参数,建立氧气高炉多流体数学模型。通过建立的模型分别对普通高炉和气化炉氧气高炉(GF-FOBF)流程中的氧气高炉进行了模拟计算,得到两种工艺流程下高炉内温度场、浓度场和速度场等典型参数的分布情况。通过对计算结果的对比,分析了氧气高炉操作条件下炉内状态的主要特征和相对于普通高炉发生的变化,发现氧气高炉内部速度场、温度场均发生变化,特别是气相组分的均匀分布问题明显。本模型可为氧气高炉流程试验及流程开发提供参考。     

Kinetics analysis of sinter-reduction base on oxygen blast furnace

The reduction experiment of sinter has been taken in oxygen blast furnace atmosphere by thermal balance weight loss method. The changes of reduction RI and reduction rate RI′ have been examined, and then kinetics analysis of sinter reduction have been carried on. Results show the reduction of sinter is significantly improving in oxygen blast furnace atmosphere and the reduction RI measures up to 98.2% when the sinter is reducing at 900 ℃. With the reduction temperature increasing, the reduction rate of sinter speeds up significantly, and the end time of reduction is shorten from 117 min at 900 ℃ to 63min at 1 100 ℃. When sinter is reducing in oxygen blast furnace atmosphere,the reductive reaction is mainly controlled by the interface chemical reaction in the beginning, and then turn to hybrid controlled by both interface chemical reaction and internal diffusion about 20 min later. The apparent activation energy of reaction that sinter reducing in oxygen blast furnace atmosphere at 900 ~ 1 100 ℃ is 38.30 kJ/mol.     

The developing of the potential flow modelling of the burden flow in a blast furnace

Potential flow theory is an alternative theory to simulate burden flow in a blast furnace. But a contour line of the flow function defined to solve the old potential flow model isn’t a stream line. In this paper, the old potential flow model is first developed to a three-equation model which should include the equations of motion and continuity, and it is proved that the contour lines of the flow function defined to solve this three-equation model are stream lines. Second, an equation capable of calculating the distribution of diameter of burden particles in blast furnace is derived from an assumption that all burden particles on a stream line has the same diameter. Finally, the developed potential flow model and the derived equation are used to simulate a final reduction reactor producing hot metal containing Cr, together with other needed transportation equations. These works would play an important improving and exemplary role in the application of potential flow theory to simulate blast furnace process and other iron-making process.     

Experiment study of adding V Ti pellet in burden structure of blast furnace

In allusion to the existing material conditions of blast furnace in Shuicheng I﹠S Corporation, rationality of sinter with V Ti pellets is studied through metallurgical performance tests of single ore. Regularity for change of reducibility, reduction degradation index, melting and dropping index changes of burden structure are researched, at increased V Ti pellets in the same proportion of sinters and different proportion of imported lump ores. The results show that sinter RI reaches 90.68%, integrated charge RDI and soft melting index are improved by adding vanadium titanium pellets. The charge structure is the best when V Ti pellets ratio at 20%, which softening starting temperature is 1 147 ℃, softening range is 156℃, dripping temperature at is 1 349 ℃, maximum pressure is 2 223 Pa and has a good permeability.     

氧气高炉工艺研究进展及新炉型设计

从氧气高炉的数学模型、实验室实验以及工业试验角度系统分析了氧气高炉工艺的发展现状及趋势,同时讨论了氧气高炉炉型的设计依据。论述了氧气高炉的静态工艺模型研究需要计算合适的直接还原度和热空区温度,同时应考虑氧气高炉工况下生产率的变化、热损失的变化、风口煤粉的喷吹上限以及N₂的循环积累等问题。指出了多维动力学模型和多目标优化模型中尚需解决的问题,以及氧气高炉数学模型的主要发展方向。结合文献研究中的氧气高炉特点,从炉身高度设计、炉腹角和炉身角设计以及风口设计3方面综述了氧气高炉炉型设计的变化规律。     

二维高炉区域BFC网格生成技术及其Matlab实现

利用数学模型对高炉冶炼过程进行模拟是高炉炼铁新工艺研发的有效方法,网格生成技术是数值模拟过程中重要的前处理过程,是高炉模拟计算的先决条件。生成网格的质量对高炉模型模拟的精度、效率以及收敛性具有重要影响,因此,建立优质的网格对高炉数学模型的求解具有重要意义。文中提出了一种适用于高炉数学模型的适体坐标系(BFC)网格的生成方法,从求解区域的划分、椭圆型方程的转换、椭圆型方程的离散及BFC网格生成步骤等方面进行了研究,并把死料区的边界作为BFC网格计算的边界条件,使数学模型的求解过程得以简化。采用带有源项的泊松方程作为变换方程,网格的正交性和疏密程度便于控制。该网格生成算法原理简单、易于编程、网格生成效率高,生成的网格能够满足数学模型求解的要求。     

A model for calculation of theoretical combustion temperature in blast furnace based on fuel calorific value

In this paper,some modifications on theoretical combustion temperature are made,and a model for calculation of theoretical combustion temperature based on the fuel(coke and coal) calorific value is developed. In the model,the incomplete combustion heat that is released by the fuel can be calculated by difference between the complete combustion heat and the heat loss because of incomplete combustion.Finally,the influence of some factors,such as coal species,coal ratio,oxygen enrichment ratio,on the theoretical combustion temperature are analyzed.     

Combination forecasting method of BTP in blast furnace under the conditions of small samples and poor information

The iron ore sintering process is a complex object with the characteristics of uncertainty, multivariable coupling, time-varying and time-delay. The burning-through-point (BTP）is affected by many factors and difficult to be controlled to the required precision by conventional control methods. A BTP prediction method is proposed by using the excellent time series prediction performance of support vector machines (SVMs), and the characteristic that Bayesian theory can make use of sample information and prior knowledge to simplify prediction model and optimize parameters．Firstly, the mechanism of BTP is analyzed, the Bayesian theory and LS-SVM are elaborated respectively, and the Bayesian evidence framework is applied to least squared support vector machine(LS-SVM） regression in order to infer non-linear models for predicting a time series．On the first level of inference, model parameters are selected and on the second level the hyper-parameters are selected．The kernel parameter are tuned on the third level framework,and on this level the relevant inputs are selected．A LS-SVM model is proposed on the basis of the Bayesian LS-SVM models. The results reveal that the BTP of sinter can be accurately predicted by this model even with small samples and poor information. It is concluded that the LS-SVM model is effective with the advantages of high precision, less samples required and simple calculation.     

Phenotyping of productivity and resilience in sweetpotato under water stress through UAV-based multispectral and thermal imagery in Mozambique

Sweetpotato is a crucial crop to guarantee food security in sub-Saharan Africa, and drought events are considered one of the most critical factors affecting sweetpotato productivity in this region. In this study, airborne imagery based on reflectance (NDVI, CI_red-edge) and canopy temperature minus air temperature (dT) indices was used to characterize sweetpotato genotypes under drought treatments in Mozambique. Two field experiments established in rainy/hot (Trial A) and dry/cool (Trial B) seasons were assessed. In Trial A, 24 genotypes were subjected to early- (ESD), mid- (MSD) and late-season (LSD) drought stress treatments and compared against a control. In Trial B, 120 genotypes were subjected to LSD only. The percentage of reduction in vine weight (PR_VW) under drought was related primarily to temporal variation of NDVI and CI, regardless of drought treatment and seasons. dT in relation to control (dT_Amp) was associated with PR_VW in ESD-Trial A and LSD-Trial B, whereas under LSD-Trial A, dT_Amp was related to total fresh storage root weight (TRW). During the rainy/hot season, higher TRW reduction was promoted under ESD; however, under LSD, it was possible to identify productive genotypes able to withstand drought stress, highlighting their relevance for drought-tolerance selection purposes.     

真空碳热还原酸浸含钛高炉渣制备TiC分析

含钛高炉渣中含有20%~30%的TiO 2,是一种附加值较高的二次资源,但在综合利用过程中存在氧化物还原难度大,硅钛难分离,二次污染严重等问题。基于热力学理论基础,采用真空碳热还原联合酸浸工艺处理含钛高炉渣制备TiC。结果表明：真空有助于钛氧化物彻底还原,可实现渣中硅钛彻底分离,减少酸耗量,降低二次污染。真空碳热还原联合酸浸工艺处理含钛高炉渣(TiO 2含量23%左右)制备TiC的最佳条件为：炉渣粒度200目,还原温度1 673 K,渣碳质量比100∶38。     

contact stress and steady thermal analysis of herringbone gears in a gas turbine

To obtain the distribution characteristic of contact stress and the bulk temperature on the surface of herringbone gears, parameter modeling of gears was carried out by parametric design language. A numerical simulation was given to calculate the contact stress field and the steady thermal field by combining heat transfer theory, tribology theory, and mesh theory. The distribution of contact stress, the bulk temperature and heat flux also were analyzed. The analysis results show that the distribution of the load along the contact line possesses regularity. The heat flux along the tooth depth direction decreases first and then increases. The effect of thermal conduction of the tooth is stronger than that of convective heat transfer. The conclusion indicates that the finite element emulation method can be used to estimate the transmission performance of herringbone gears.     

Brake disc thermal stress in material composite design

The temperature distribution and thermal stress distribution of brake discs under emergency braking conditions were studied using the finite element method (FEM). The discs were of three types: those made of functionally graded SiCp/Zl104 composite materials, of uniform (20% volume) SiCp/Zl104 composite materials, and of compacted graphite iron, respectively. The rule of mixtures of dual phase material and the discretization of the material composition distribution were applied to estimate the material properties of functionally graded composite materials. The results show that the temperature and thermal stress of brake discs made of graded SiCp/Zl104 composite are the lowest among the three types studied, and the distribution of temperature and thermal stress of this brake disc type is more uniform than the others. Furthermore, brake discs made of functionally graded SiCp/Zl104 composite can reduce vehicle weight and increase wear resistance capacity. The results provide a theoretical foundation for fabricating brake discs made of graded SiCp/Al composite material.     

Analysis of a major rice blast resistance gene in the rice restorer line Hanghui 1179

Rice blast, caused by the fungal pathogen Magnaporthe oryzae, is one of the most devastating diseases of rice (Oryza sativa) worldwide. Identification and utilization of resistance genes in rice breeding is considered to be an effective and economical method to control this disease. Hanghui 1179 (HH1179) is a new native rice restorer line developed in South China. The hybrids derived from HH1179 show broad-spectrum resistance against rice blast in South China, and a further understanding of the genetic resistance in HH1179 will provide useful information for breeding resistant cultivars. In the present study, we used bulked segregant analysis combined with specific-length amplified fragment sequencing to identify a dominant gene from HH1179 that provides resistance against the rice blast isolate GD13-14. Association analysis indicated that the resistance gene is located on chromosome 6 and we mapped the target gene to a 100.8 kb region (between markers InDel-8 and RM19818) that contains the Pi2/Pi9/Piz/Piz-t/Pi50 gene cluster. Candidate gene prediction and cDNA sequencing indicated that the target resistance gene in HH1179 is Pi2. Our findings will be valuable for resistance breeding with restorer line HH1179.     

Combustion characteristics and kinetic analysis of blended coal ofupgraded low rank coal and bituminous coal injected into blast furnace

Thermo-gravimetric analysis is performed to study the combustion performance of upgraded low rank coal,bituminous coal injected into blast furnace and their mixture.It’s studied the relationship between adding quantity of upgraded low rank coal and change rules of blended coal combustion index and their influence on each other.Blended combustion kinetics is analyzed by using the distributed activation energy model (DAEM).The results indicate that the combustion rate of upgraded low rank coal is faster than that of bituminous coal.With the increase of adding quantity of upgraded low rank coal in the blended coal,the ignition temperature gradually decreases,the combustible index and comprehensive combustion index increase,and burning effect gets better.The value of interaction factors K of all blended coals are greater than 1,which suggests that the mutual promotion between upgraded low rank coal and bituminous coal in the combustion process exists.The apparent activation energy of blended coals decrease with the increase of adding quantity of upgraded low rank coal,which indicates the combustion activity of blend coal gradually stronger.     

铜胁迫对小白菜品质的影响

外界铜胁迫会植株硝酸盐含量减少,NR活性和Vc含量也有类似变化,而可溶性蛋白含量先是略有增加,铜浓度较高时则显著减少,可溶性糖含量也会上升,但超过一定浓度又会呈现明显的下降趋势。     

Technological Economic Analysis of TwistingThermal Insulated Direct-Buried pipe

This paper describes the technological process in producing twisting thermal insulated pipe and compares it with the traditional method in China.In the paper,a technological economic analysis is made as well to compare the twisting thermal insulated direct-buried pipes with underground tunnel laying ones.     

Genotypic response of faba bean to water stress

Forty resistant rice cultivars were studied for theinheritance of resistance to bacterial blight usingPhilippine races of Xanthomonas oryzae pv.oryzae (Xoo). Results showed that all thevarieties have at least two recessive genes forresistance. One of these genes governs resistance torace 1 (PXO61) while the other gene confers resistanceto race 6 (PXO99). In addition to the recessivegenes, nine of the varieties possess another dominantgene which also confers resistance to race 1.Allelism tests revealed that the recessive genesgoverning resistance to race 1 in 39 varieties areallelic to xa5 while the dominant genes in thenine varieties are allelic to Xa4. Therecessive gene conferring resistance to race 1 incultivar Sada Diga is inherited independently of xa5. Similarly, the recessive genes governingresistance to race 6 in all the varieties arenon-allelic to xa13. The allelic relationshipsof these genes with xa-24(t), a new recessivegene identified in cultivar DV86 which conveysresistance to race 6 are now being investigated.     

Intellectual prediction of a permeability index for blast furnaces

The permeability index for blast furnaces is an important monitoring parameter in their operation. Proper trend prediction of the permeability index is important for good operation. Support vector machines (SVM) combined with wavelet analysis are adopted to build a forecasting model. Four historic values of a permeability index are analyzed by a wavelet analysis via seven levels. Based on eight wavelet analyzed values and combined with operating parameters, eight sub models are built using the least square support vector machines method. The prediction components are reconstructed to obtain a forecast. The details of modeling, validation and result analyses are presented.     

Identification of a major blast resistance gene in the rice cultivar 'Tetep'

Analysis of near‐isogenic lines (NILs) indicated the presence of a novel resistance gene in the indica rice cultivar ‘Tetep’ which was highly resistant to the rice blast fungus Magnaporthe grisea.‘Tetep’ was crossed to the widely used susceptible cultivar ‘CO39’ to generate the mapping population. A Mendelian segregation ratio of 3 : 1 for resistant to susceptible F₂ plants further confirmed the presence of a major dominant locus, in ‘Tetep’, conferring resistance to the blast fungal isolate B157, corresponding to the international race IC9. Simple sequence length polymorphism (SSLP) was used for molecular genetic analysis. The analysis revealed that the SSLP marker RM 246 was linked to a novel blast resistance gene designated Pi‐tp(t) in ‘Tetep’.     

An experimental investigation of a single jet into fluid flow in a pipe

An experimental investigation is performed on a single jet issuing into a flow in a pipe. The pressure of the flow in pipe is measured under the condition when there is a right angle between the jet and the mainstream and the velocity of the jet is 1 to 6 times of the mainstream. The results show that, there exists a jet core with skewing downstream near the entrance port; the pressure in that core increases slightly with the fluid incidence. Outside the core, the pressure of the flow inside the pipe increases significantly; the pressure increment is correlated with the velocity of the jet quadratic dependence.