Energy saving analysis for CO_(2)–O_(2)mixed injection technology in converter steelmaking

Energy-saving in China's iron and steel industry still relies on the development and improvement of short-term energy saving technologies.Therefore,a special converter smelting technology incorporating energy saving was proposed.To evaluate the energy-saving potential of the CO_(2)–O_(2)mixed injection(COMI)technology,collected production data were used to develop an improved techno-economic model.Calculations reveal that the technology can save energy through auxiliary material consumption,sensible heat of solid by-product,iron loss reduction,and energy recovery.The application of COMI technology in an enterprise is cost effective,involving the energy saving potential of 0.206 GJ/t,the cost of conserved energy of−48.83 yuan/GJ,and a simple payback period of 0.35 year for a 60-million-yuan investment.Sensitivity analysis shows that the investment cost and discount rate primarily influence the cost of conserved energy of the technology.As the discount rate increased,the cost of conserved energy also gradually increased.Overall,the COMI technology is an energy-saving technology with good development prospects.

Influence of bottom blowing oxygen on dust emission in converter steelmaking

With the importance of the steelmaking industry in the economy and its negative impacts on the environment,reducing dust emissions is a vital focus in this field.Thus,the theory of dust generation in converter steelmaking process was analyzed and the influence of bottom blowing oxygen on dust generation was obtained through experimental research.The industrial test was carried out in a 120-t bottom combined blown O_(2)–CaO steelmaking converter.The results show that lowering the lance position can reduce the amount of dust.This emission rate of the converter is also found to be in direct proportion to the decarburization rate.As a result,the proposed bottom blowing O_(2)–CaO steelmaking converter can technically reduce the amount of dust and improve the recovery rate of iron.With more bottom blowing oxygen,the dust content is lower with the dust peak appearing earlier.The evaporation theory,followed by the bubble theory,plays the primary role in the dust generation of bottom blowing oxygen steelmaking.It points out the direction for the technology research and development of reducing dust generation.

Effect of different bottom blowing elements on stirring characteristics of molten bath in converter

The bottom blowing element is the key equipment to ensure the bottom blowing effect of the converter.Three types of bottom blowing elements,dispersive type(D1),double circular seam(D2)and straight cylinder type(D3),were built,and the effects of bottom blowing element type on molten bath flow,wall erosion and furnace bottom erosion were simulated.It was found that when the bottom blowing elements of dispersive type(D1)and double circular seam(D2)were used,the dead zone area in the lower part of the molten bath was smaller,and the high-speed zone area was larger;therefore,the stirring effect on the bottom melt was better.When the straight cylinder type(D3)bottom blowing element was used,the gas penetrated the molten bath at a faster rate to reach the surface of molten bath and failed to disperse in the bottom molten bath,and the wall shear stress near the nozzle outlet was larger.When argon was blown by three different bottom blowing elements,the area of the wall shear stress greater than 3 Pa was 4.8,5.6 and 8.7 cm2,respectively,within 0.2 m of the bottom blowing nozzle outlet.

Behavior of phosphorus enrichment in dephosphorization slag at low temperature and low basicity

At low basicity and low temperature, the dephosphorization behavior and phosphorus distribution ratio(LP) between slag and molten steel in the double slag and remaining slag process were studied with a 180 t basic oxygen furnace industrial experiment.The dephosphorization slags with different basicities were quantitatively analyzed.At the lower basicity range of 0.9–2.59, both LP and dephosphorization ratio were increased as the basicity of dephosphorization slag increased.Dephosphorization slag consisted of dark gray P-rich, light gray liquid slag,and white Fe-rich phases.With increasing basicity, not only did the morphologies of different phases in the dephosphorization slag change greatly, but the area fractions and P2O5 content of the P-rich phase also increased.The transfer route of P during dephosphorization can be deduced as hot metal → liquid slag phase + Fe-rich phase → P-rich phase.

Physical modelling of particle transport phenomenon and vibration behavior of converter with bottom powder injection

A cold model of top-bottom blown converter was set up to study the particle transport phenomenon and vibration performance of converter with bottom powder injection.The effect of bottom blowing flow rates,tuyere diameters,arrangements,and powder to gas mass ratios on powder distribution and furnace body vibration was investigated.The results show that the bottom injection parameters and modes have significant effects on the particle transport behavior and furnace vibration.The powder dispersion uniformity and furnace vibration increase with the increase in bottom blowing tuyere diameters.In the lower range of bottom blowing flow rates and powder to gas mass ratios,the powder dispersion uniformity is improved with the increase in them.However,in the higher range,the excessive furnace vibration leads to reduction in uniformity in powder dispersion.When the bottom blowing tuyeres arrange at double arrangement of 0.5R(R refers to the radius of the bottom)distance between tuyere and center of bath bottom,the converter has optimal particle transport behavior and vibration performance.The vibration law of converter with bottom powder injection was revealed by deducing the empirical formulas of furnace vibration maximum amplitude.The vibration intensity is affected by Froude number,powder to gas mass ratio,and tuyere arrangement.

Monitoring and diagnosis of complex production process based on free energy of Gaussian–Bernoulli restricted Boltzmann machine

Online monitoring and diagnosis of production processes face great challenges due to the nonlinearity and multivariate of complex industrial processes.Traditional process monitoring methods employ kernel function or multilayer neural networks to solve the nonlinear mapping problem of data.However,the above methods increase the model complexity and are not interpretable,leading to difficulties in subsequent fault recognition/diagnosis/location.A process monitoring and diagnosis method based on the free energy of Gaussian-Bernoulli restricted Boltzmann machine(GBRBM-FE)was proposed.Firstly,a GBRBM network was established to make the probability distribution of the reconstructed data as close as possible to the probability distribution of the raw data.On this basis,the weights and biases in GBRBM network were used to construct F statistics,which represents the free energy of the sample.The smaller the energy of the sample is,the more normal the sample is.Therefore,F statistics can be used to monitor the production process.To diagnose fault variables,the F statistic for each sample was decomposed to obtain the Fv statistic for each variable.By analyzing the deviation degree between the corresponding variables of abnormal samples and normal samples,the cause of process abnormalities can be accurately located.The application of converter steelmaking process demonstrates that the proposed method outperforms the traditional methods,in terms of fault monitoring and diagnosis performance.