Abstract: In order to better treat high-concentration refractory organic wastewater, the optimum conditions and treatment effect for treating wastewater from Tobias acid production were studied in a batch-type supercritical water oxidation (SCWO) device by SCWO technology. Through single factor and orthogonal tests, the removal rates of COD and chrominance were investigated under different experimental conditions. When the temperature is 380℃, the pressure is 24 MPa, the residence time is 150 s and the excess oxygen rate is 1. 8, the removal rates of COD and chrominance reaches 96. 7% and 97. 5%, respectively, and the biodegradability of the wastewater is improved greatly.
Abstract: The low-temperature selective catalytic reduction (SCR) denitrification of a flue gas was carried out with Ce-MnOx/ACFN. The denitrification efficiencies were studied by modifying the activated carbon fibers (ACF) and changing the Ce-MnOx loading capacity, Ce/Mn molar ratio and operating conditions respectively. Ce-MnOx/ACFN as a SCR denitrification catalyst has good activity at 70-110℃. The denitrification efficiency increases with rising temperature, and it improves obviously after the ACF is modified by nitric acid. With the increasing of Ce-MnOx loading capacity and Ce/Mn molar ratio, the denitrification efficiency increases firstly and then decreases; but with the increasing of NH3/NO molar ratio in the inlet flue gas, it increases firstly and then tends to be stable. When the volume fraction of vapor in the inlet flue gas is above 8% the denitrification efficiency decreases with the vapor volume fraction increasing.
Abstract: Sulfur balance calculations were performed according to production data from Shougang Jingtang Steel Sintering Plant. The impact weight of each sintering material on SO2 concentration in sintering waste gas was analyzed, based on which some reasonable assumptions were made. In combination with the uniform measurement method of SO2 emission concentration for different sintering machines in Chinese standards, a relation formula between sulfur content in the sintering materials and judging index for SO2 emission concentration was deduced and a control criterion for low-sulfur sintering materials was established. If Shougang Jingtang Steel Sintering Plant wants to meet the SO2 emission concentration of 500 mg·m-3, the sulfur content in the sintering mixture need reduce to below 0. 032%; if it wants to meet the SO2 emission concentration of 200 mg·m-3, the sulfur content in the sintering mixture need reduce to below 0. 013%, but it is very difficult to realize under the current material condition.
Abstract: In order to meet the need of low oxygen content under the deep desulfurization conditions of hot metal, the variation of oxygen content in hot metal was studied by the thermodynamic method when the Al-C-O equilibrium reached. Compared the deoxidation constants of the C or Al single deoxidizer with the Al-C complex deoxidizer, it is found that at 1 573 K the deoxidation ability of Al-C complex deoxidation is stronger than that of C deoxidation during hot metal pretreatment. The equilibrium curve of Al-C complex deoxidation at 1 573 K can be drawn by using the thermodynamic theory. If the temperature is constant, the deoxidation ability of Al-C complex deoxidation increases with the carbon activity aC increasing; but if aC is constant, the deoxidation ability of Al-C complex deoxidation lowers as the temperatures rises.
Abstract: C-Mn steel was deoxidized with titanium at 1 600℃ for 15 min,then deoxidized with a MgSi alloy for different time,and at last the deoxidized samples were quenched.The effects of trace magnesium-deoxidizing time on the size distribution,composition and morphology of inclusions in Ti-deoxidized steel were systematically investigated by using an ASPEX Explorer SEM/EDS automatic analyzer system.With the prolonging of Mg-deoxidizing time,the particle number gradually decreases but the particle size increases.The size distribution of particles is in line with the normal distribution function.Since MgAl2O4-rich and TiOx-rich complex inclusions aggregate and float upward,the inclusion types change from MgAl2O4-rich,TiOx and MgO-rich complex inclusions to MgAl2O4-rich and MgO-rich complex inclusions.In addition,shortening the Mg-deoxidizing time is beneficial to a cast specimen with high number per volume unit and tiny MgAl2O4-rich,MgO and TiOx-rich complex inclusions.
Abstract: Heavy metal elements such as Cr, Ni and Zn were extracted from stainless steel-making dust through the direct reduction and melting process on the basis of thermodynamic analysis. Carbon deoxidization experiment results show that the optimal carbon addition percentage in the dust is 20%, and the lowest reduction temperature is 1 050℃ for Fe, Ni and Zn and 1 400℃ for Cr, which are in agreement with the thermodynamic calculation results. These metals can be selectively reduced through controlling the temperature. According to direct reduction and melting experiment results, the optimal melting temperature of the Fe-Cr alloy is 1 550℃, metals in the dust are extracted as the Fe-Ni-Cr alloy, and the slag is separated from the metals quite well. The metal extraction rate is about 75% after 5 min reaction; but after 15 min reaction the Fe and Cr extraction rates surpass 85%, while the Ni extraction rate is over 90%. These experimental results indicate that it is completely feasible to return the stainless steel-making dust to the steel-making main flow and recycle its heavy metals by controlling the carbon content, reduction time and temperature without modifying the present process.
Abstract: Si-rich films were deposited on pure iron and low-Si steel substrates by direct current magnetron sputtering, and then were subjected to vacuum annealing. The distribution characteristics of Si across Fe and low-Si steel substrates were studied by energy spectrum analysis (EDS) and X-ray diffraction (XRD). DICTRA software was used to simulate the diffusion models. It is found that the diffusion behavior of Si in the Fe substrate is from γ-Fe(Si) phase to α-Fe(Si) phase and the rate of diffusion is controlled by phase-boundary migration. When the content gradient of Si along the cross section is not sufficient to drive the phase interface to positively migrate, the phase interface moves back with the increase of diffusion time, and the diffusion process tends to be a uniform diffusion process with the time passing. But in the low-Si steel substrate, the diffusion behavior of Si accords with the Fick's second law of diffusion.
Abstract: A low-activation F/M steel 12Cr3WVTa micro-alloyed with V and Ta was designed by Thermo-Calc thermodynamic simulation in combination with experimental methods. Its microstructure and precipitation after water quenching at 1 050℃ and then tempering at 780℃ were examined by means of optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive spectrometry (EDS). The results show that the microstructure of the steel after quenching and tempering contains mainly tempered martensite with a small amount of δ-ferrite, as well as precipitates M23C6 and MX (M=V, Ta; X=C, N). M23C6 carbides distribute mainly along the lath boundaries and the phase interfaces, while MX precipitates within the tempered martensite and the δ-ferrite. The steel has good tensile properties at room temperature and high temperature (600℃), and its tensile strength and yield strength are 507 MPa and 402 MPa at 600℃, respectively, which meets the tensile property requirements of cladding tubes for supercritical water cooled reactors (SCWR).
Abstract: The electrochemical corrosion behavior of 20# carbon steel in NACE solutions containing different mass concentrations of H2S (0, 95. 61, 103. 22, and 224. 16 mg·L-1) at different temperatures (25, 35, and 45℃) was investigated by potentiodynamic polarization tests, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The formation mechanism of corrosion products was also discussed. It is found that the corrosion rate of the carbon steel increases significantly with the addition of a small amount of H2S in the NACE solution by promoting both the anodic iron dissolution and the cathodic hydrogen evolution. The corrosion current density of the carbon steel enhances with the increment of H2S concentration. As the temperature of the electrolyte solution increasing, the corrosion rate also increases. The outer loose corrosion products are mainly iron carbonate; but corrosion products formed on the steel surface are mainly composed of iron sulfides.
Abstract: The stress corrosion cracking (SCC) behavior of an ultrahigh strength steel 300M in a 3. 5% NaCl solution was studied by potentiodynamic polarization and slow strain rate tests (SSRT), and the fracture surfaces at different applied potentials were observed by scanning electron microscopy (SEM). The SCC mechanism of 300M steel in the NaCl solution at open circuit potential is attributed to anodic dissolution. Cl-ions significantly increase the SCC sensitivity of 300M steel. At the anodic applied potential of-600 mV the anodic dissolution rate and SCC susceptibility of 300M steel increase, represented by the loss of reduction-in-area at open circuit potential increasing from 52. 6% to 99. 5%. Cracks generally initiate at corrosion pits and the SCC mechanism remains anodic dissolution. At the cathodic potential of-800 mV, 300M steel exhibits a lower SCC sensitivity due to cathodic protection. Its strength and toughness values are close to those in air. The SCC is controlled by anodic dissolution and hydrogen induced cracking. When the applied potential is more negative than #950 mV, 300M steel exhibits a higher SCC sensitivity. The SCC mechanism is hydrogen induced cracking due to a synergistic action of stress and hydrogen.
Abstract: Zn-Al-Mg-La-Ce coatings were prepared by electric arc spraying,and their corrosion behavior was studied with salt spray test.The characteristics of the coatings before and after corrosion were investigated by energy dispersive spectrometry(EDS),X-ray diffraction(XRD),scanning electron microscopy(SEM),polarization curves,and electrochemical impedance spectroscopy.It is shown that the coatings have outstanding self-sealing effectiveness,and their structures are compact.During corrosion,microscopic pores on the surfaces of the coatings can be jammed with their own corrosion products,thus forming a dense corrosion product layer to prevent from further corrosion.Consequently,the corrosion resistance of Zn-Al-Mg-La-Ce coatings is superior to that of normal coatings.
Abstract: The influence of Cu doping on the properties, phase transformation and microstructure of ZnTiO3 films was investigate. Experiments were performed with Cu depositing on ZnTiO3 ceramic targets by RF magnetron sputtering at substrate temperatures, and by controlling the Cu content, different Cu-doped ZnTiO3 films were deposited on SiO2/Si substrates. ESCA analysis shows that the mass fractions of Cu in the Cu-doped ZnTiO3 films are 0. 84%, 2. 33%, and 2. 84%. XRD analysis reveals that the Cu-doped ZnTiO3 films are amorphous at normal temperature; after annealed at 600℃ the films transforms from amorphous to Zn2Ti3O8 crystalline phase, but there is no crystalline phase in the pure ZnTiO3 film annealed at 600℃. The Zn2Ti3O8 phase decomposes into Zn2TiO4 phase and TiO2 phase, and the lattice of ZnTiO3 changes little because the Zn2+ position is replaced by Cu ions when annealing at 900℃. XRD, SEM and TEM analyses show that the formation of TiO2 phase would be inhibited when doping too much Cu. When Cu2+ substitutes for Zn2+ in an ABO3 structure, it leads to the formation of twin-crystals which is attributed to the lattice strain. This result can be confirmed by TEM analysis. With the precipitation of excessive Cu, the average grain size gradually becomes small and the lattice strain is also decreased, so that the lattice constant returns to the original level.
Abstract: This paper presents a cathode surface structure to improve the performance of a zinc-air fuel cell (ZAFC). The electrolyte of the zinc-air fuel cell was made by mixing organic inhibitor with a potassium hydroxide solution. Open-circuit voltage performance test and constant-current discharge test were carried out to investigate the differences in voltage-current characteristics and power density of the zinc-air fuel cells with different cathode surface structures and to compare the corrosion resistances of different air-cathodes in the electrolyte. The materials analysis and microstructure observation of air-cathodes after discharging were performed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Experimental results show that a protection layer on the air-cathode can increase the durability and corrosion resistance of the electrode. This electrode structure is able to decrease corrosion damage occurred at the air-cathode surface and provide a stable electrochemical reaction. It can improve the utilization of the air-cathode greatly in the zinc-air fuel cell.
Abstract: A method for predicting cold gas content in a melter-gasifier was proposed based on entropy-weighted fuzzy C-means clustering and partial least squares(PLS).In the modeling process,an entropy-weighted fuzzy C-means clustering algorithm is used to get the clustering result of burden calculation reports according to the consumption of raw materials at first.Then,different prediction models are built based on a PLS algorithm for various cluster types.The real field data of cold gas content from Baosteel COREX-1# were used for verification.It is shown that the method can build the prediction model of COREX cold gas content effectively,and has an advantage in prediction accuracy.
Abstract: An order analysis method was proposed which utilizes short time Fourier transforms(STFT) based on frequency shift(FS-STFT).In the algorithm,by using the convolution properties of Fourier transforms in the frequency domain,the original signal is multiplied by e-j2πfit in the time domain,and the spectrum energy of fi is shifted to the position of zero frequency.Other spectrum energies can be got at the position of zero frequency when fi is changed according to a certain frequency interval.As a result,the frequency resolution of STFT is improved in the time-frequency analysis.Then local threshold de-noising was used in the time-frequency domain,and the change of speed signals was tracked.Eventually,the mothod was applied to the order analysis of varying speed machinery.A comparison of analysis results between STFT and FS-STFT shows that the method can track actual speed signals accurately.The order analysis for faulty bearings using the method in the deceleration process also demonstrates that the fault frequency can be extracted successfully.
Abstract: Aimed at the problem of matching open-order slabs and coils with hot rolling production orders in the steel industry,a multi-objective 0-1 nonlinear integer programming model for integrative matching of inventory in continuous casting and hot rolling processes was established on the basis of the integrative management idea.Two matrices were introduced in the model:one indicated the difference between slab material and steel grade required in orders,and the other reflected the difference between coil grade and steel grade required in orders.An improved genetic algorithm with the sub-integer encoding method and the heuristic repair strategy was proposed.Finally,the effectiveness of the proposed model and algorithm was verified by simulation based on actual production data.The results show that the integrative matching method can produce a significantly better and more scientific way for matching slabs and coils with hot rolling production orders.
Abstract: This paper aims at the cost reduction of the joint inventory as a alliance constituted by a supplier and a retailer.The cost difference of the supply chain before and after implementing the joint inventory is calculated by considering the shortage cost into the inventory cost analysis model.The reduced cost is regarded as the residual income,which is distributed between the supplier and the retailer based on the Rubinstein bargaining model.Theoretical analysis results show that implementing the joint stock system reduces the cost of the supply chain,gets the amount of cost reduction,and allocates effectively the amount of cost reduction between the supplier and the retailer.An example demonstrates the feasibility and maneuverability of this method.
Abstract: An optimization and composition algorithm based service workflow templates in network environment was proposed in this paper. The algorithm turns the problem of service optimization and composition into a problem of service workflow templates, thus it can largely reuse history workflow templates and decrease the buildup work of new workflow templates. In the algorithm, optimization makes the structure of the service workflow more reasonable and the execution time shortened. A network stream media coursewaremaking service workflow as an example was modeled with a Petri net. The comparison of SPNP performance analysis results of the service workflow between pre-optimization and post-optimization proves the algorithm's effectiveness.
Abstract: An approach to construct a 3-band scaling filter and a wavelet filter was proposed,which not only is of orthogonality,symmetry and compact support but also has high vanishing moments.By setting the vanishing moment and switching the orthogonality of the scaling filter,this approach effectively reduces the number of unknown variables during the process of constructing the scaling filter and the complexity of the calculation process.Subsequently,a decomposition scheme of the polyphase matrix with paraunitary property was proposed on the basis of the lattice structure theory.Using this decomposition scheme,the corresponding wavelet filters are constructed whose impulse response length is 9 and vanishing moment is 3 and whose impulse response length is 15 and vanishing moment is 3 or 4,respectively.Finally,multi focus image fusion is implemented by using these wavelet filters.Experimental data show that the fusion result is better by using these 3-band wavelets than by using dyadic wavelets.
Abstract: This paper used an ultrasonic wave method and an impact-echo method to measure pressure wave velocities in full scale columns,block specimens with different thickness,cruciform specimens,and beam/column joints by obliquely placing transducers on the opposite faces.The results were then compared with those by direct measurement using an ultrasonic device to evaluate the accuracy of oblique measurement.The feasibility of quality evaluation for the concrete at the beam/column joint using the measured pressure wave velocities by oblique measurement was discussed.The test results showed that,the measured wave velocity went down sharply when the wave receiver deviated more than 40 cm for the measurement on a 40 cm width full scale column by the ultrasonic wave method.However,the measured wave velocity would begin to go down when the wave receiver deviated more than 70 cm using a 3 mm diameter steel ball as the impacting wave source by the impact-echo method.Using a 6 mm diameter steel ball,the deviation distance could reach up to 100 cm.Using a 9 mm diameter steel ball or a small hammer,the measured wave velocity would not go down even when the deviation distance was up to 300 cm.All test results on the specimens showed that,the wave velocity measured by the ultrasonic wave method basically went down when the deviation distance of the receiver increased,but the wave velocity measured by the impact-echo method was not affected.When compared with ultrasonic direct measurement,the wave velocity errors of the impact-echo method were well within ±3%.
Monthly, started in 1955 Supervising institution：Ministry of Education Sponsoring Institution：University of Science and Technology Beijing Editorial office：Editorial Department of Chinese Journal of Engineering Publisher：Science Press Chairperson：Ren-shu Yang Editor-in-Chief：Ai-xiang Wu ISSN 2095-9389CN 2095-9389
