Fundamental Study on Coke Degradation in BF with Oxygen Enriched Blast and High Hydrogen Atmosphere

The effects of gas composition, temperature, ore to coke ratio and prereduction rate of ore on coke degradation were studied. The results showed that 1% increment in solution loss of coke reduces coke strength by 0.6%, and the coke degradation is accelerated with the temperature. The higher the temperature, the more coke surface is involved in reactions, and the less negative effect on coke strength is. Hydrogen exerts stronger effect on coke degradation than CO at high temperature. The coke degradation is decreased with the reduction of ore to coke ratio and increase of ore prereduction rate.

Influence of oxygen-rich hot air composite gas medium on sintering performance and function mechanism

Hot air sintering technology is used to improve the quality and production efficiency of sintered ore.However,the current thick layer condition highlights the disadvantage of the low oxygen potential of the hot air sintering layer.Therefore,it is considered to use oxygen enrichment sintering to improve the environment of hot air sintering.Traditional sintering,hot air sintering,and oxygen-rich hot air sintering were compared through sintering cup experiments,and the influence of hot air and oxygen-rich hot air on sintering indexes was clarified.Hot air reduced the vertical sintering velocity,while improved the yield and tumbler index.Oxygen-rich hot air sintering contributed to improving the vertical sintering velocity while ensuring the quality of sintered ore,thus comprehensively improving production efficiency.Under the action of hot air,the highest temperature of the sintering layer increased and the high-temperature holding time was prolonged.After oxygen enrichment,the combustion efficiency of fuels in the upper layer of materials was promoted,which optimized heat distribution in the middle and lower layers of materials and increased the content of calcium ferrite in the sintered ore,thus strengthening the sintering process.

Distribution characteristics of indoor oxygen concentration under natural ventilation in oxygen-enriched buildings at high altitudes

Diffuse oxygen supply is an important means to improve the indoor oxygen environment of buildings and ensure physiological and psychological health of immigrants in plateau areas.Existing research on oxygen enrichment strategies at high altitudes has mainly focused on confined spaces under mechanical ventilation,with few studies on the distribution of indoor oxygen concentration under natural ventilation in actual buildings.This study used a verified computational fluid dynamics(CFD)method to investigate the indoor oxygen distribution with practical consideration of natural ventilation at high altitudes.The results showed that the oxygen distribution under wind-driven natural ventilation was more nonuniform than that under buoyancy-driven natural ventilation,with the ratio of local oxygen concentration to overall-mean oxygen concentration,the k value,between 0.8 and 1.3 under wind-driven natural ventilation and between 0.9 and 1.1 under buoyancy-driven natural ventilation.The effects of meteorological condition and oxygen source position on indoor spatial oxygen distribution characteristics were explored with careful examination in human occupied zone under lying,sitting and standing postures.The results can provide implications for effective and energy saving design of indoor oxygen supply system in plateau buildings.

Novel oxygen-enrichment method using annular air curtain for single-head roadway of plateau mine

The low-oxygen environment restricts the exploitation of mineral resources on plateaus and affects miner’s safety.This paper proposes an oxygen-enrichment method using an annular air curtain.Through numerical simulation and experiments,it was confirmed that the proposed method improves the breathing environment in the single-head roadway of a plateau mine.Computational fluid dynamics(CFD)was used to investigate the oxygen-enriching effect and oxygen spatial distribution regularities after using the proposed oxygen-enrichment method in the single-head roadway of a plateau mine.The reliability of the CFD model was confirmed by experiment.Orthogonal testing was conducted to investigate the influence degree and optimal level combination of factors influencing oxygen enrichment.The results demonstrate that the annular air curtain effectively prevented oxygen loss,thus forming a local oxygen-rich space and improving the effective utilization rate of oxygen.Oxygen supply concentration and velocity are positively correlated with the oronasal oxygen mass fraction through a linear function,while the air curtain outlet wind velocity is negatively correlated with the oronasal oxygen mass fraction through a linear function.The annular air curtain diameter and oronasal oxygen mass fraction do not have an obvious functional relationship.When the annular air curtain diameter was greater than 0.9 m,the oronasal oxygen mass fraction was stable at approximately 25.30%.The influencing factors of the novel oxygen-enrichment method are,in descending order,as follows:oxygen supply concentration,annular air curtain diameter,air curtain outlet wind velocity,and oxygen supply velocity.The optimal level combination is oxygen supply concentration of 100%,oxygen supply velocity of 11 m/s,air curtain outlet wind velocity of 1.5 m/s,and annular air curtain diameter of 0.9 m.

Effect of oxygen enrichment on sintering behavior of high proportion vanadium-titanium magnesite concentrates

To achieve high-efficiency utilization of complex and unmanageable iron-containing minerals,the effects of oxygen enrichment on productivity,yield,flame front speed,exhaust gas peak temperature,and desulphurization reaction of the vanadium-titanium magnetite sintering process as well as sinter tumble index and mineralogy were clarified,with oxygen enrichment concentrations ranging from 21 to 29 vol.%.Results indicated that with increasing the oxygen enrichment concentration from 21 to 27 vol.%,the flame front speed increased from 30.3 to 40.0 mm min^(-1),the yield enhanced from 72%to 77%,and the productivity augmented from 1.83 to 2.67t m^(-2)h^(-1);in the meantime,the tumble index was improved from 73.7%to 77.9%,and the exhaust gas peak temperature rose from 376.4 to 484.8℃.The main reason for the improvement in sintering properties was the increased combustibility of fuels and the generation of proper liquid phase that improved the permeability of the packed bed.The improved sinter strength is mainly due to the increase in the phase fraction of silico-ferrites of calcium and aluminium.In addition,oxygen enrichment sintering could significantly increase the desulphurization level of vanadium-titanium magnetite sinter and the rate of desulphurization reaction during sintering process.

The treatment of black-odorous water using tower bipolar electro-flocculation including the removal of phosphorus,turbidity,sulfion,and oxygen enrichment

The large amount of municipal wastewater discharged into urban rivers sometimes exceeds the rivers’self-purification capacity leading to black-odorous polluted water.Electro-flocculation has emerged as a powerful remediation technology.Electro-flocculation in a bubble column tower with a bipolar electrode(BPE)was tested in an attempt to overcome the high resistance and weak gas-floatation observed with a monopolar electrode(MPE)in treating such water.The BPE reactor tested had a Ti/Ta2O_(5)-IrO_(2)anode and a graphite cathode with an iron or aluminum bipolar electrode suspended between them.It was tested for its ability to reduce turbidity,phosphate and sulphion and to increase the concentration of dissolved oxygen.The inclusion of the bipolar electrode was found to distinctly improved the system’s conductivity.The system’s electro-flocculation and electrical floatation removed turbidity,phosphate and sulphion completely,and the dissolved oxygen level improved from 0.29 to 6.28 mg/L.An aluminum bipolar electrode performed better than an iron one.Changes in the structure of the microbial community confirmed a significant improvement in water quality.

Optical investigation on polyoxymethylene dimethyl ethers spray flame at different oxygen levels in a constant volume vessel

In this paper,high-speed imaging and spectrometry diagnostics were used to study the spray flame structures and emission spectra of polyoxymethylene dimethyl ethers(PODE)in an optical constant volume vessel.The effects of oxygen volume fraction(15%to 80%)on some typical combustion characteristics such as spatially integrated natural intensity,flame propagation speed,lift-off length and the distribution of flame emission spectra were investigated.The results show that the PODE spray flame mainly exhibits blue chemiluminescence,which is different from the diesel yellow diffusion flame dominated by soot radiation.As the oxygen concentration increases,the flame natural luminosity and propagation speed increases,the position of lift-off region and flame tip move towards the injector nozzle,and the flame width becomes narrower.According to the spectral results,the blue chemiluminescence generated by carbon monoxide oxidation dominates the PODE flame luminescence,suggesting that no soot is formed.The increase in oxygen concentration leads to enlarged intensity and gradient of PODE flame radiation.In summary,the combination of PODE and oxygen-enriched combustion shows no soot formation and promotes the oxidation of carbon monoxide and unburned hydrocarbon.This study can provide more insights into PODE spray combustion,and offer guidelines for achieving efficient and clean combustion.

Experimental investigation on possibility of oxygen enrichment by using gradient magnetic fields

This paper presents a novel method that uses the interception effect of gradient magnetic field on oxygen molecules to realize enrichment.The use of two opposite magnetic poles of two magnets at a certain distance forms a magnetic space having a field intensity gradient near its borders.When air injected into the magnetic space outflows from the magnetic space via its borders,oxygen molecules in the air will experience the interception effect of the gradient magnetic field,but nitrogen molecules will outflow from the magnetic space without hindrance.Thus,continuous oxygen enrichment is realized.The enrichment degree of oxygen reaches 0.65%when the inlet and outlet air flows are 40 mL/min and 20 mL/min,respectively,and the gas temperature is 298 K and the maximal product of magnetic flux density and its gradient is 563 T2/m(the distance between two magnetic poles is 1 mm).When the gas temperature rises to 343 K,the enrichment degree drops to 0.32%;and when the maximal product of magnetic flux density and field intensity gradient drops to 101 T2/m(the distance between two magnetic poles is 4 mm),the enrichment degree drops to 0.23%.The experimental results show that there is an optimal ratio between the inlet air flow and the outlet air flow.Under the experimental conditions in this paper,the value is about 2.0.It is demonstrated that the method presented in this paper can continuously enrich oxygen and has a higher enrich-ment degree than other oxygen-enrichment methods using magnetic separation.