chun Yao

An innovative energy-saving in-flight melting technology and its application to glass production.

Abstract The conventional method used for glass melting is air-fuel firing, which is inefficient, energy-intensive and time-consuming. In this study, an innovative in-flight melting technology was developed and applied to glass production for the purposes of energy conservation and environmental protection. Three types of heating sources, radio-frequency (RF) plasma, a 12-phase alternating current (ac) arc and an oxygen burner, were used to investigate the in-flight melting behavior of granulated powders. Results show that the melted particles are spherical with a smooth surface and compact structure. The diameter of the melted particles is about 50% of that of the original powders. The decomposition and vitrification degrees of the prepared powders decrease in the order of powders prepared by RF plasma, the 12-phase ac arc and the oxygen burner. The largest heat transfer is from RF plasma to particles, which results in the highest particle temperature (1810 °C) and the greatest vitrification degree of the raw material. The high decomposition and vitrification degrees, which are achieved in milliseconds, shorten the melting and fining times of the glass considerably. Our results indicate that the proposed in-flight melting technology is a promising method for use in the glass industry.

Innovative in-flight glass-melting technology using thermal plasmas

A stable 12-phase AC arc was generated by transformers at a commercial electric power system, and the arc behavior was characterized by image analysis. For the unique advantages, the multiphase AC arc was developed to apply to in-flight glass melting for the purpose of energy-saving and emission reduction. The effects of electrode configuration and sheath gas flow rate on the arc and melting behavior of granulated glass raw material were investigated. Results show that the discharge behavior and the high-temperature region can be controlled by the electrode configuration. The luminance area of the high-temperature region and its fluctuation reflect the discharge behavior. The vitrification degree of glass raw material is mostly dependent on the center temperature of arc. As sheath gas flow rate increases, the ratio of luminance area decreases and the center temperature of arc increases.

Optimization of the Process Parameters for the Synthesis of LiFe1-x-yMgxTiyPO4/C Cathode Material Using Response Surface Methodology

A systematic approach was used to develop the empirical model for optimizing the preparation process parameters for the synthesis of LiFe1−x−yMgxTiyPO4/C composite cathode material. For optimizing the production parameters, response surface methodology (RSM) was applied to develop a linear regression model and maximize the discharge capacity. Analysis of the variance (ANOVA) showed that the three variables (Mg-dopant, Ti-dopant and sintering temperature) and the interactions among them were significant factors. Response surfaces formed by RSM illustrated that the doping of Mg and Ti on Fe site had obviously synergistic effect on the discharge capacity. In the process optimization, the parameters were 2.9% of Mg-dopant, 3.0% of Ti-dopant and sintering temperature of 678.5∘C, corresponding to a discharge capacity of 136.7mAh/g predicted by the model. This predicted value was in good agreement with the actual value (136.4mAh/g) by confirmatory experiment. The optimized LiFe0.941Mg0.029Ti0.030PO4/C composite ...

Optimization of the Process Parameters for the Synthesis Process of Battery-Grade Ferrous Oxalate by Response Surface Method

This study investigates the optimal conditions for the synthesis of battery-grade ferrous oxalate as a raw material for preparing cathode material. Ferrous oxalate was prepared by liquid-phase precipitation method using ferrous sulfate and oxalic acid. Central composite design (CCD) was used to determine the effects of three preparation variables on purity and particle size: reaction temperature, aging time and concentration of ferrous sulfate. Based on CCD, the significant factors on each experimental design response identified the analysis of variance (ANOVA). The optimum ferrous oxalate preparation conditions were obtained reaction temperature of 31.32∘C, aging time of 56.52min, and ferrous sulfate concentration of 5%. Under these optimum conditions, ferrous oxalate with purity of 99.69% and particle size of 4.92μm was obtained as best product which met and exceed the requirements of battery-grade ferrous oxalate. In addition, the special morphologies of ferrous oxalate prepared under different dispers...

Modeling and numerical analysis of thermal treatment of granulated porous particles by induction plasma

In this paper it is aimed to describe the modeling and numerical analysis of thermal treatment of granulated porous particles by induction plasma. To investigate the heat exchange dynamics between plasma and particles during the flight of granulated porous particles through the hot plasma, a plasma-particle interactive flow model has been developed. This model solves the conservation equations to predict the temperature and flow fields of plasma, under local thermal equilibrium (LTE) conditions, and then computes the injected particles trajectories, temperature and size histories, and the particle source terms to incorporate the particle loading effects. It is found that the size and dose of injected particles greatly affect the particle trajectory and temperature, and hence the heat transfer to particles at higher powder feed-rate.

Surface modification and characterization of F-Co doped spinel LiMn2O4

Abstract Spinel LiCo 0.09 Mn 1.91 O 3.92 F 0.08 as cathode material was modified with LiCoO 2 by the sol-gel method, and the crystal structure, morphology and electrochemical performance were characterized with XRD, SEM, EDS, AAS and charge-discharge test in this paper. The results show that a good clad coated on parent material can be synthesized by the sol-gel method, and the materials with modification have perfect spinel structure. LiCo 0.09 Min 0.09 O 3.92 F 0.08 materials coated by LiCoO 2 improve the stability of crystal structure and decrease the dissolution of Mn into electrolyte. With the LiCoO 2 content increasing, the specific capacity and cycle performance of samples are improved. The capacity loss is also suppressed distinctly even at 55 °C.

Preparation of Nickel Nanoparticles by Direct Current Arc Discharge Method and Their Catalytic Application in Hybrid Na-Air Battery

Nickel nanoparticles were prepared by the arc discharge method. Argon and argon/hydrogen mixtures were used as plasma gas; the evaporation of anode material chiefly resulted in the formation of different arc-anode attachments at different hydrogen concentrations. The concentration of hydrogen was fixed at 0, 30, and 50 vol% in argon arc, corresponding to diffuse, multiple, and constricted arc-anode attachments, respectively, which were observed by using a high-speed camera. The images of the cathode and anode jets were observed with a suitable band-pass filter. The relationship between the area change of the cathode/anode jet and the synchronous voltage/current waveform was studied. By investigating diverse arc-anode attachments, the effect of hydrogen concentration on the features of nickel nanoparticles were investigated, finding that 50 vol% H2 concentration has high productivity, fine crystallinity, and appropriate size distribution. The synthesized nickel nanoparticles were then used as catalysts in a hybrid sodium–air battery. Compared with commercial a silver nanoparticle catalyst and carbon black, nickel nanoparticles have better electrocatalytic performance. The promising electrocatalytic activity of nickel nanoparticles can be ascribed to their good crystallinity, effective activation sites, and Ni/NiO composite structures. Nickel nanoparticles prepared by the direct current (DC) arc discharge method have the potential to be applied as catalysts on a large scale.

In-flight Melting Behavior of Granulated Alkali-Free Raw Material in Induction Thermal Plasmas

A new in-flight glass melting technology with induction thermal plasmas was developed to reduce the energy consumption and the emissions of greenhouse gases for glass production. The effects of carrier gas on the in-flight melting behavior of granulated alkali-free raw material were investigated by various modern analyses. Results show that the particles have smooth spherical surface and compact structure after heat treatment. As the carrier gas flow rate increases, the vitrification degree decreases and the average diameter increases. Higher vitrification results in more shrinkage of particle. The carbonates in raw material decompose completely during in-flight melting. The highest volatilization of B2O3 is attributed to more heat transferred from plasmas to particles at the lowest carrier gas flow rate.

In-flight melting of granulated powders by 12-phase AC arc discharge for glass production

Current glass melting technology, based on the Siemens furnace developed in 1860s, has evolved in response to manufacturing requirement. However few revolutionary changes to the basic technology have occurred. Glass production is still one of the most energy intensive industries, because the conventional method used for glass melting is air-fuel firing, which is inefficient, energy-intensive and time-consuming. With increased energy issue and global warming, it is urgent to develop a new technology to save energy and reduce emissions for glassmaking. In view of high temperatures of thermal plasmas, an innovative in-flight glass melting technology with an induction plasma, a multiphase AC arc, and an oxygen burner was developed. In this study, characteristics of the treated powders by a 12-phase AC arc during their flight time were investigated. The reagents for alkali-free glass was mixed and prepared into granulated powders with the grain size of 20-80 mum by spray dry method. The granulated powders were injected into a 12-phase AC arc for the in-flight treatment. The stable 12- phase AC arc discharge with 100 mm in diameter was obtained at the power of 46 kW. The vitrification, morphology, size distribution, and composition of the treated powders were characterized to evaluate the melting characteristics. Results show that the melted particles are spherical with a smooth surface and compact structure. Higher vitrification and decomposition degrees of raw material as well as higher volatilization of B2O3 are attributed to larger heat transferred to per particle under smaller flow rate of carrier gas and lower feed rate of granulated powders. The properties of glass powders were strongly dependent on the feed rate and the carrier gas flow rate. The high decomposition and vitrification degrees, which are achieved in milliseconds, shorten the melting and fining times of glass considerably. Our results indicate that the proposed in-flight melting technology is a promising method for use in the glass industry.