Relationship between pinguecula formation and exposure to tandoor ovens in a hospital-based study

AIM: To investigate the relationship between pinguecula and the use of tandoor ovens.METHODS: A total of 539 women, ranging in age from20 to 86 y who attended an outpatient clinic were enrolled. All the patients were asked whether they used tandoor ovens. Women exposed to tandoor ovens(n =286) were accepted as participants in the study group and they were compared with participants in the control group(n =253). The age, presence of pinguecula,duration of exposure to tandoor ovens as years and occupations were recorded for all the subjects.RESULTS: Mean duration for exposure to tandoor was20.26y(range 1-62y) in the study group. The rate of pinguecula in the study group was 82.2%(235/286), and the rate in the control group was 37.5%(95/253); this difference was statistically significant(P 【0.05).Pinguecula was seen in 61.2%(330/539) of all the participants.CONCLUSION: Pinguecula is strongly associated with exposure to tandoor ovens.

Research and Application of Wear Resistant Refractories for Cooling Zone of Large Scale Coke Dry Quenching Ovens

In order to prolong the service life of the cooling zone of large scale coke dry quenching ovens,six kinds possible refractories for the cooling zone of large scale coke dry quenching ovens： SiC containing brick A,SiC containing brick B,mullite-andalusite brick,spinel containing brick,zirconia containing brick,corundum-mullite brick and grade B mullite brick,were analyzed in properties. It is found that the cooling zone lining adopting SiC containing bricks or mullite-andalusite bricks has much longer service life. Based on this,a new type of wear resistant brick was developed. The brick has a compressive strength of 135 MPa,a wear loss of 2. 10cm^3（only a quarter of that of the grade B mullite brick）,and a higher bulk density than the grade B mullite brick. The application of the brick in a 140t·h^（-1）coke dry quenching oven showed that it performed better than the grade B mullite brick. The cooling zone adopting the new bricks has a lower coke discharging temperature,which is beneficial to the enhancement of heat recovery efficiency and steam power generation.

Advanced green refractory technologies for coke ovens at Baosteel

To construct world-class iron and steel enterprises, Baosteel has adopted a strategy of environmental management that emphasizes environmental protection in the low-carbon and ecological manufacturing of steel products. In recent years, Baosteel has developed a series of advanced green refractory technologies （including composite refractory precast blocks with a unique ceramic glaze, and high-thermal-conductivity/high-density silica brick） for use in Baosteel coke ovens. The results of these applications not only reduce production costs and increase production efficiency, but also facilitate clean production by coke ovens. Baosteel＇ s coke oven has become China＇ s leading example of the application of green refractories.

Damage Mechanism and Structure Analysis of Used Clay Checker Bricks for Regenerators of Coke Ovens

During long-term use,the clay checker bricks for regenerators of coke ovens on gas side react with the impurities containing Fe and K20,causing foaming,softening and deformation,which is not only related with the impurity content and properties of the clay checker bricks,but also related with the type and the composition of the dust in the gas.After long term use,the clay checker bricks of coke ovens on air side have relative lower impurities containing Fe and K20.The inferior clay checker bricks,with high impurity content and high porosity,are easy to pulverize and deteriorate due to the oxidationreduction reaction with the iron oxide and the gas.The gas quality shall be concerned for long service life of the coke oven regenerators.

On-site raw gas cut-off during the shut down of Baosteel phaseⅠcoke ovens

The preparation and implementation of raw coke oven gas cut-off, which was the key process involved with shutting down the Baosteel phase I coke ovens, were investigated, and the main technical points and countermeasures are presented.

Optimization and Simulation of Inclined Channel Area Lining for CDQ Ovens

The mechanical force borne by the lintel and“brackets”in the inclined channel area of CDQ and the thermal stress generated by the top-down temperature gradient were simulated by ANSYS software.The following conclusions are drawn.(1)The mechanical force has very mild effect on the damage of the“brackets”.(2)The temperature gradient caused by the uneven temperature distribution of CDQ oven is the key factor affecting the“bracket”damage.The different expansion of refractory materials in various parts results in the thermal stress concentration which tears the“brackets”.(3)The structure adjustment of the“brackets”has very little effect on the thermal stress distribution.(4)The multi-phase nitride bonded silicon carbide for CDQ can effectively alleviate the stress concentration at the“brackets”,realizing the long-life and stable operation.

Development Work at JYFL:Plasma Potential Measurements,Electron Heating Simulations,JYFL-MMPS,High Temperature Ovens

Extensive plasma potential measurements have been carried out using a device developed at JYFL. In this article the main results of the measurements will be summarized.A new simulation code to study the electron heating is being developed.One objective of the code is to determine the change of the electron loss cone when the magnetic field component of the electromagnetic wave is taken into account along with the permittivity of the plasma.As a part of the work,accurate X-ray measurements have been initiated. A new plasma chamber based on the MMPS-concept(Modified MultiPole Structure)has successfully been constructed and tested with the JYFL 6.4GHz ECRIS.The results and conclusions will be presented elsewhere in these proceedings.In the same article,a new concept of ECRIS and first results will be presented.The active development work of evaporation ovens has been carried out in a joint European collaboration(ISIBHI). The objective of the task is to make the operation of the oven reliable at 2000℃for several days.Both resistively and inductively heated ovens have been studied and further developed.The status of this work will be presented.

基于LabVIEW与Proteus的测控仿真实验系统设计

以单片机远程温度控制系统为例,给出了一种基于LabVIEW与Proteus的测控仿真实验系统的设计方法,利用Proteus中的AT89C51单片机仿真下位机运行,实现温度的采集、A/D转换器的控制及向上位机传输数据等功能。利用LabVIEW仿真上位机运行,对接收的温度信息进行PID控制,将PID调整量输出给单片机,使其输出占空比可调的PWM波,以控制OVEN的工作状态,达到远程控制系统温度的目的。LabVIEW设计的监控界面直观地实现了对温度信号的实时监控和仿真参数的设置。两软件利用Virtual Serial Port Driver 6.9虚拟的一对串口进行RS-232的串行通信。仿真结果表明,该方法可以有效地验证测控系统设计的正确性,对于测控实验教学与工程项目开发的前期实验,具有很好的实用性。

Effect of Cr2O3 addition on oxidation induration and reduction swelling behavior of chromium-bearing vanadium titanomagnetite pellets with simulated coke oven gas

The oxidation induration and reduction swelling behavior of chromium-bearing vanadium titanomagnetite pellets(CVTP)with Cr2O3 addition were studied,and the reduction swelling index(RSI)and compressive strength(CS)of the reduced CVTP with simulated coke oven gas(COG)injection were investigated.The results showed that the CS of the CVTP decreases and the porosity of the CVTP increases with increasing amount of Cr2O3 added.The Cr2O3 mainly exists in the form of(Cr,Fe)2O3 solid solution in the CVTP and as Fe-Cr in the reduced CVTP.The CS of the reduced CVTP increases and the RSI of the reduced CVTP decreases with increasing amount of Cr2O3 added.The limited aggregation and diffusion of metallic iron contribute to the formation of dense lamellar crystals,which leads to the slight decrease for reduction swelling behavior of reduced CVTP.This work provides a theoretical and technical basis for the utilization of CVTP and other Cr-bearing ores such as chromite with COG recycling technology.

Partial oxidation of simulated hot coke oven gas to syngas over Ru-Ni/Mg(Al)O catalyst in a ceramic membrane reactor

Hydrogen amplification from simulated hot coke oven gas （HCOG） was investigated in a BaCo0.7Fe0.2Nb0.1O3-δ （BCFNO） membrane reactor combined with a Ru-Ni/Mg（Al）O catalyst by the partial oxidation of hydrocarbon compounds under atmospheric pressure. Under optimized reaction conditions, the dense oxygen permeable membrane had an oxygen permeation flux around 13.3 ml/（cm^2·min）. By reforming of the toluene and methane, the amount of H2 in the reaction effluent gas was about 2 times more than that of original H2 in simulated HCOG. The Rn-Ni/Mg（Al）O catalyst used in the membrane reactor possessed good catalytic activity and resistance to coking. After the activity test, a small amount of whisker carbon was observed on the used catalyst, and most of them could be removed in the hydrogen-rich atmosphere, implying that the carbon deposition formed on the catalyst might be a reversible process.

Influence of hydrogen-enriched atmosphere under coke oven gas injection on reduction swelling behaviors of oxidized pellet

It is of great importance to elucidate reduction swelling behaviors and reaction mechanism of oxidized pellet in hydrogen-enriched atmosphere under coke oven gas injection. In this work, the effects of hydrogen concentration in N_2-CO-H_2 atmosphere with unchanged CO content on reduction swelling behaviors of oxidized pellet at 1173 K were studied, to clarify the mechanism of hydrogen-enriched reduction and exclude the influences of CO. Then, the reduction swelling behaviors of oxidized pellet at 1173 K in actual atmosphere under coke oven gas(COG) injection, got from the simulation results of multi-fluid blast furnace model, were investigated. The results show that with the concentration of hydrogen increasing in N_2-CO-H_2 gas from 2% to 18%, the reduction swelling index of pellet decreases from 10.12% to 5.57% while the reduction ratio of pellet increases obviously from 39.85% to 69.58%. In addition, with COG injection rate increasing from 0 to 152.34 m^3/t, the reduction swelling index of pellet decreases slightly from 10.71% to 9.54% while the reduction ratio of pellet is increased from 31.57% to 36.39%. The microstructures of pellet are transformed from the platy structure to the flocculent structure.

Effect of B2O3 addition on oxidation induration and reduction swelling behavior of chromium-bearing vanadium titanomagnetite pellets with simulated coke oven gas

The oxidation induration and reduction swelling behavior of the chromium-bearing vanadium titanomagnetite pellets (CVTP) with B2O3 addition were investigated. Besides, the reduction swelling index (RSI) and compressive strength (CS) of the reduced CVTP were also examined using the simulated coke oven gas (COG). The results suggested that the CS of CVTP was increased from 2448 to 3819.2 N, while the porosity of CVTP was decreased from 14.86% to 10.03% with the increase in B2O3 addition amounts. Moreover, the B2O3 mainly existed in the forms of TiB0.024O2 and Fe3BO5 in both CVTP and the reduced CVTP. Specifically, the CS of the reduced CVTP was elevated from 901 to 956.2 N, while the RSI was reduced from 5.87% to 3.81% as the B2O3 addition amounts were increased. Taken together, B2O3 addition would facilitate the aggregation and diffusion of metallic iron particles, which contributed to reducing the formation of metal iron whiskers and weakening the reduction swelling behavior.

Hydrogen production via chemical looping reforming of coke oven gas

Coke oven gas(COG)is one of the most important by-products in steel industry,and the conversion of COG to value-added products has attracted much attention from both economic and environmental views.In this work,we use the chemical looping reforming technology to produce pure H_(2) from COG.A series of La1-xSrxFeO_(3)(x?0,0.2,0.3,0.4,0.5,0.6)perovskite oxides were prepared as oxygen carriers for this purpose.The reduction behaviors of La1-xSrxFeO_(3) perovskite by different reducing gases(H_(2),CO,CH4 and the mixed gases)are investigated to discuss the competition effect of different components in COG for reacting with the oxygen carriers.The results show that reduction temperatures of H_(2) and CO are much lower than that of CH4,and high temperatures(>800℃)are requested for selective oxidation of methane to syngas.The co-existence of CO and H_(2) shows weak effect on the equilibrium of methane conversion at high temperatures,but the oxidation of methane to syngas can inhibit the consumption of CO and H_(2).The doping of suitable amounts of Sr in LaFeO_(3) perovskite(e.g.,La0.5Sr0.5FeO_(3))significantly promotes the activity for selective oxidation of methane to syngas and inhibits the formation of carbon deposition,obtaining both high methane conversion in the COG oxidation step and high hydrogen yield in the water splitting step.The La0.5Sr0.5FeO_(3) shows the highest methane conversion(67.82%),hydrogen yield(3.34 mmol g^(-1))and hydrogen purity(99.85%).The hydrogen yield in water splitting step is treble as high as the hydrogen consumption in reduction step.These results reveal that chemical looping reforming of COG to produce pure H_(2) is feasible,and an O_(2)-assistant chemical looping reforming process can further improves the redox stability of oxygen carrier.

Thermal Fission Rate Calculated Numerically by Particles Multi-passing over SaddlePoint

Langevin simulation of the particles multi-passing over the saddle point is proposed to calculate thermal fission rate. Due to finite friction and the corresponding thermal fluctuation, a backstreaming exists in the process of the particle descent from the saddle to the scission. This leads to that the diffusion behind the saddle point has influence upon the stationary flow across the saddle point. A dynamical correction factor, as a ratio of the flows of multi- and first-overpassing the saddle point, is evaluated analytically. The results show that the fission rate calculated by the particles multi-passing over the saddle point is lower than the one calculated by the particle firstly passing over the saddle point, and the former approaches the results at the scission point.

Perovskite-type oxygen-permeable membrane BaCo_(0.7)Fe_(0.2)Nb_(0.1)O_(3-δ) for partial oxidation of methane in coke oven gas to hydrogen

Perovskite-type oxygen-permeable membrane reactors of BaCo0.7Fe0.2Nb0.1O3-δ （BCFNO） packed with Ru-based catalyst had high oxygen permeability and could be used for hydrogen production by partial oxidation of methane in coke oven gas （COG）. At 1173 K, 94% of methane conversion, 85% of H2 selectivity, 107% of CO selectivity, and as high as 15.4 mL·cm^-2·min^-1 of oxygen permeation flux were obtained. The BCFNO membrane itself had poor catalytic activity to partial oxidation of CH4 in COG. During continuous operation for 70 h at 1173 K, no degradation of the membrane reaction performance was observed. XRD and SEM characterization also demonstrated that the BCFNO membrane reactor exhibited good stability in partial oxidation of methane in COG.

Conversion and reaction kinetics of coke oven gas over a commercial Fe-Mo/Al_2O_3 catalyst

Producing methanol from coke oven gas(COG) is one of the important applications of COG. Removal of sulfur from COG is a key step of this process. Conversion and reaction kinetics over a commercial Fe-Mo/Al2O3 catalyst(T-202) were studied in a continuous flow fixed bed reactor under pressures of 1.6-2.8 MPa, space time of 1.32-3.55 s and temperatures of 240-360 °C. Though the COG contains about 0.6 mol/mol H2, hydrogenation of CO and CO2 is not significant on this catalyst. The conversions of unsaturated hydrocarbons depend on their molecular structures. Diolefins and alkynes can be completely hydrogenated even at relatively low temperature and pressure. Olefins, in contrast, can only be progressively hydrogenated with increasing temperature and pressure. The hydrodesulfurization(HDS) of CS2 on this catalyst is easy. Complete conversion of CS2 was observed in the whole range of the conditions used in this work. The original COS in the COG can also be easily converted to a low level. However, its complete HDS is difficult due to the relatively high concentration of CO in the COG and due to the limitation of thermodynamics. H2 S can react with unsaturated hydrocarbons to form ethyl mercaptan and thiophene, which are then progressively hydrodesulfurized with increasing temperature and pressure. Based on the experimental observations, reaction kinetic models for the conversion of ethylene and sulfur-containing compounds were proposed; the values of the parameters in the models were obtained by regression of the experimental data.

Performance of a tubular oxygen-permeable membrane reactor for partial oxidation of CH_4 in coke oven gas to syngas

A gas-tight BaCo 0.7 Fe 0.2 Nb 0.1 O 3-δ（BCFNO） tubular membrane was fabricated by hot pressure casting.And a membrane reactor with BCFNO tubular membrane and Ag-based sealant was readily constructed and applied to partial oxidation of CH4 in coke oven gas.At 875 ℃,95% of methane conversion,91% of H 2 and as high as 10 ml cm-2·min-1 of oxygen permeation flux were obtained.There was a good match in the coefficient of thermal expansion between Ag-based alloy and BCFNO membrane materials.The tubular BCFNO membrane reactor packed with Ni-based catalysts exhibited not only high activity but also good stability in hydrogen-enriched coke oven gas（COG） atmosphere.

Hydrogen production from simulated hot coke oven gas by catalytic reforming over Ni/Mg(Al)O catalysts

Hydrogen production by catalytic reforming of simulated hot coke oven gas （HCOG） with toluene as a model tar compound was investigated in a fixed bed reactor over Ni/Mg（Al）O catalysts. The catalysts were prepared by a homogeneous precipitation method using urea hydrolysis and characterized by ICE BET, XRD, TPR, TEM and TG. XRD showed that the hydrotalcite type precursor after calcination formed （Ni, Mg）Al2O4 spinel and Ni-Mg-O solid solution structure. TPR results suggested that the increase in Ni/Mg molar ratio gave rise to the decrease in the reduction temperature of Ni^2＋ to Ni^0 on Ni/Mg（Al）O catalysts. The reaction results indicated that toluene and CH4 could completely be converted to H2 and CO in the catalytic reforming of the simulated HCOG under atmospheric pressure and the amount of H2 in the reaction effluent gas was about 4 times more than that in original HCOG. The catalysts with lower Ni/Mg molar ratio showed better catalytic activity and resistance to coking, which may become promising catalysts in the catalytic reforming of HCOG.

Comparison Between Conventional Convective Heating and Microwave Heating: An FTIR Spectroscopy Study of the Effects of Microwave Oven Cooking of Bovine Breast Meat

The effects of microwave energy and conventional convective heating on bovine meat were studied in the mid-infrared region by FTIR spectroscopy, to highlight the differences between the two cooking methods. Samples of 100 g of bovine breast meat were cooked using three treatments: heating in a conventional electric oven at the temperature of 165°C for 16 min, heating in a microwave oven at 800 W for 95 sec, and heating in the same microwave oven at 650 W for 160 sec. Significant decreases in intensity of vibration bands of CH2 methylene group at 1921 and 1853 cm-1 and of the carbonyl band at 1742 cm-1 were observed after microwave heating with respect to heating in a conventional oven, showing that Maillard reaction occurs partially using microwave oven. Spectral analysis in the amide I region after microwave cooking at 800 W for 95 sec showed that an increase in intensity occurred in the region from 1665 to 1690 cm-1 which can be attributed to β-turns, characteristic of disorder processes in the protein. Further analysis after microwave cooking at 650 W for 160 sec evidenced major increase in intensity of β-turns content and the appearance of significant increases of β-sheet component at 1635 cm-1 and 1695 cm-1 that can be attributed to aggregated β-sheets structures.

An innovative method to calculate oxygen consumption rate

Based on heat and mass transfer characteristics of spontaneous combustion of coal,Arrhenius equation and the Ranz-Marshall correlation,a novel approach was proposed in this paper to estimate oxygen consumption rate of self-ignition of coal at high temperature.Compared with the conventional methods,this approach involves not only kinetic properties of self-ignition of coal and temperature,but also the ambient air flow characteristics and diameter of coal particle.To testify the proposed approach,oxygen consumption rates at high temperature were measured by the programmable isothermal oven experiments.Comparisons between experimental and theoretical results indicate that the rates of oxygen depletion calculated by the proposed approach agree well with those measured from laboratory-scale experiments,which further validates the proposed approach.