Calculation results and analysis of gas flow properties in tuyère under the influence of heat source

The flow properties of the gases in an annular‐tube type tuyère used for an 18 t AOD vessel were analyzed using the equations and calculation formulas presented in Part I of this work. The influence of the heating and friction effects, the gas supply pressure, and the gas type and composition, on the properties were examined. The results showed that the properties in a tuyère are significantly changed due to the presence of a heat source. This has a similar effectiveness as increasing the friction action and obviously reduces the gas flowrate at the tuyère outlet. When designing a tuyère used in a practical process of metallurgy and calculating the flow properties of gas in the tuyère, the heating effect from the high temperature melt and refractory lining should be taken into account. The gas supply pressure has a decisive effect on the properties. The type and composition of the blowing gas will also influence the properties. For a given tuyère and blowing system, appropriate blowing pressures for different gases, particularly for subtuyère gases, should be used according to the technological requirements of the different refining periods.     

轧钢加热炉重油与高炉煤气混烧供热优化

分析了重油、高炉煤气混烧存在高炉煤气临界供热份额及供热盲区，给出了相应的计算方法和在不同条件下实现供热优化的控制措施。     

Increase in the efficiency of electric melting of pellets in an arc furnace with allowance for the energy effect of afterburning of carbon oxide in slag using fuel–oxygen burners

The problems of increasing the efficiency of electric steelmaking using fuel–oxygen burners to supply oxygen for the afterburning of effluent gases in an arc furnace are considered. The application of a new energy-saving regime based on a proposed technology of electric melting is shown to intensify the processes of slag formation, heating, and metal decarburization.     

化工生产区域尾气治理系统设计实践

随着环保要求的日益严格,南钢燃供厂针对化工生产区域尾气治理进行了有效的尝试,提出了具体工艺方案,并在实施运行后不断完善、改进。     

天然气燃烧特性及其与其它燃气的互换性分析

介绍了天然气的供应、价格;分析了天然气的燃料特性和燃烧特性;用AGA法,对天然气和一种城市煤气进行了燃气互换性计算,结果表明二者不能互换;最后,讨论了天然气利用时应注意的问题。     

Dynamics of the process of gas transport into the body using a mathematical model

Dynamics of mass-transport of oxygen, carbon dioxide, and inert gases in lungs, blood, and tissues, as well as gas transport through alveolar capillary and erythrocyte membranes at rest and during exercise under normal and increased ambient pressures, were studied on a mathematical model. The model consists of 34 differential and 58 algebraic equations and makes it possible to estimate the dynamics of changes of over 90 parameters. The effect of various factors: duration of the respiratory cycle, tidal volume, airways resistance, the surface of diffusion, the resistance of alveolar-capillary wall, erythrocyte membrane, ventilation-perfusion relations, pulmonary blood shunts, blood supply to the tissues, Haldane and Verigo-Bohr effect, buffer capacity of the blood, and others) on the mass-transport of gases were quantitatively estimated.     

Improvement of thermal modes of shaft furnaces of nonferrous metallurgy

Based on the experimental data of research into the thermal and gas-dynamic operation of shaft melting furnaces of nonferrous metallurgy, the main regularities in the development of thermal and gas-dynamic processes over the longitudinal and transverse sections of the aggregate are established. It is suggested to vary the nonuniformity of conditions of the heat treatment of starting materials by improvement of the uniformity of gas distribution due to the optimization of the tuyere supply of air blasting and materials with the use of distributive facilities. The efficiency of using a series of verified methods to vary the production parameters of the shaft smelting is shown, including the organized selection of gases from the layer of batch materials; using the energy of the acoustic field; heating the air blast to a temperature no lower than 300°C; enriching the air blast with oxygen; and introducing additions of natural gas, which is burned immediately in the batch layer.     

Simulation of tuyere–raceway system in blast furnace

Abstract

A uniform distribution of the blast is an important prerequisite of a balanced blast furnace operation, because the blast is the main source of the hot gases that are needed to preheat, reduce and melt iron ores. The supply of hot gas from the raceways is not necessarily uniform along the furnace periphery, but depends on flow resistances encountered on the individual bustle main tuyere–raceway–raceway boundary routes. A model for this system has been developed in order to study and analyse the effects of changes in tuyere parameters and boundary conditions. Variables such as the total blast volume, blast pressure, tuyere diameter and the combustion degree of injected reductants in the tuyeres can be studied. An online version of the model has also been developed to track how the conditions on the tuyere level change with time in operating blast furnaces.     

制氧机故障进供氧系统的优化决策

建立了钢铁厂制氧机故障时的供氧系统优化决策模型,并具体应用在宝钢能源部的智能管理系统中。通过开发实例,详细说明了模型构造的思路和方法。系统可对钢铁企业的气体用户和气体部门进行供需平衡规划,给出符合决策者意图的专家决策,实现气体的合理利用。该系统充分体现了智能化的特点,使用方便,使决策者能够在决策过程中充分介入。     

Effect of Zr Additions on the Oxidation Kinetics of FeCrAlY Alloys in Low and High <Emphasis Type="Italic">p</Emphasis>O<Subscript>2</Subscript> Gases

Alloys of nominal composition Fe-20Cr-5Al-0.05Y (mass pct) with and without a 0.03 pct Zr addition were isothermally oxidized at temperatures of 1473 to 1573 K (1200 to 1300 °C) in both flowing Ar-O₂ and Ar-H₂-H₂O. Continuous thermogravimetric (TG) measurements of oxygen uptake showed the rates to be faster in both gases for Zr-containing than for the Zr-free alloy. Scale growth on the Zr-bearing alloy by inward oxygen diffusion is accelerated by the fine alumina grain size and the formation of elongated zirconia particles in the two-phase scales. Zirconia formation ceases when the supply of metal in the thin alloy substrate is exhausted, and subsequent single-phase alumina growth proceeds at a slower rate. A simple diffusion model is shown to account semiquantitatively for zirconium enrichment in alumina scales. The presence of hydrogen modifies both oxygen transport in the scale and its permeability in the alloy.     

Effect of the Amount of Gases on the Foaming Efficiency of Porous Aluminum Using Die Castings Fabricated by Friction Stir Processing

Porous aluminum was fabricated by friction stir processing using the gases intrinsically contained in aluminum alloy die castings without the use of a blowing agent. The effect of the amount of gases contained in the die castings on the foaming efficiency was investigated. Although the expansion efficiency of each type of gas was not clear, the total amount of gases was sufficient to obtain high porosity. A porosity of approximately 60 pct was obtained with highly spherical and fine pores.     

Improving the energy efficiency of blast furnaces by means of hot reducing gases

Groundbreaking energy-saving blast-furnace technologies are needed to reduce the energy costs in the production of hot metal and converter steel. The reduction in coke consumption and increase in productivity when hot reducing gases are injected into the blast furnace are assessed on the basis of calculations and industrial trials. The composition of the reducing gases is described before and after compression of the blast-furnace gases. Systems for recycling the blast-furnace gas and removing the CO₂ are considered. The economic and energy benefits obtained by the injection of hot reducing gases are appraised. The energy efficiency of hot-metal production is increased by 40%.     

Cleaning of waste gases in the production of alloys that contain rare-earth metals

A simple and effective system has been developed to clean the waste gases formed in small furnaces. It is proposed that a 5–10% solution of Ca(OH)₂ be used to neutralize SO₂ in the gases. The correct amount of solution to use has been determined. Activated charcoal of the 3–20 mm fraction has been tried as the adsorbent and can be used repeatedly after desorption. A high degree of efficiency is obtained in cleaning the waste gases: 88–99% for charges of composition I and 91–98% for charges of composition II. __________ Translated from Metallurg, No. 5, pp. 26–27, May, 2006.     

Thermoregulatory and metabolic responses following cardiac surgery

The thermoregulatory responses in 13 haemodynamically stable patients were evaluated over a 7-h period following coronary artery bypass graft surgery. Cutaneous vasoconstriction was defined by a forearm-to-fingertip skin temperature gradient (delta Tskin) > or = 4 degrees C and muscular hyperactivity was assessed by integrating the electromyographic signals (iEMG). Blood gases and lactate were measured in arterial, mixed venous and femoral venous blood. After arrival in ICU, we observed: (1) mild central hypothermia (Tc = 34.8 +/- 0.6 degrees C) and elevated peripheral vascular resistance in all the patients; (2) delta Tskin > or = 4 degrees C in 11 of 13 patients that persisted until a median Tc of 37.1 degrees C was achieved; (3) a transient increase in iEMG (+ 18%) was accompanied by an increase in total body O2 uptake (+ 28%); (4) elevated muscle O2 extraction rate (56 +/- 18% after 3 h) and lactate release. These data suggest that residual hypothermia in sedated patients after cardiac surgery elicits appropriate thermoregulatory responses that are associated with transient O2 supply/uptake mismatch within skeletal muscles.     

矿井智能通风联动调控理论与供需匹配实验研究

鉴于矿井通风系统动态匹配自动化调节的现场需求,分析了风量供需匹配原理与联动调控方法,建立了多元特征融合的主通风机调频、关联分支调阻及联合调节的数学模型。提出了通风网络分支供需匹配调控模型和稳定性判定方法,基于有毒有害气体涌出（排放）预测的需风模型,开发了矿井通风供需偏离的智能化应急调控软件。实现了通风供需失衡选择变频调节时,自动计算通风机最佳工作频率;选择关联分支风阻调节时,运用元胞自动机模型计算出最佳调节巷道,并通过风网反演计算模型获取调节风阻值;当单一调节方式失效时,生成风机变频与分支调阻联合调控方案;通过风网超前模拟分析实现风量供需匹配的可靠调节。运用典型矿井通风系统建立了风网分支需风量自动化调节实验模型,以现场有毒有害气体超限统计规律为分支需风量调控导向模型开展调风稀释实验,结果表明:三种调节方式下分支风量严格按照调控理论模型变化,调风过程中CO₂浓度变化延时明显,风机变频调节的风网波动较小,分支风阻调节对局部风网影响大,联合调节风网波动性大。实验验证了矿井通风供需匹配智能化调控系统的实用性和可行性,为矿井通风联动调控提供理论和应用指导。      

Partial cardiopulmonary bypass in rats for evaluating ischemia-reperfusion injury

The authors developed a miniaturized partial cardiopulmonary bypass model in rats by using membrane oxygenators. Sprague-Dawley rats underwent general anesthesia and tracheostomy for ventilation. Partial cardiopulmonary bypass was carried out through the jugular cannula (18 gauge) for venous blood drainage and through the femoral arterial cannula (24 gauge) at a flow of 50 ml/kg/min. Membrane oxygenators used in this study maintained arterial oxygen tensions (PaO2) at 300-500 mmHg and carbon dioxide tensions (PaCO2) at 25-35 mmHg, with a gas mixture of 95% O2 + 5% CO2 (n = 7) for at least 2 hr of bypass circulation. To test the feasibility of this system for investigation of ischemia-reperfusion injury, hypoxic challenges with gas mixtures of different oxygen concentrations were examined. After equilibration of the bypass circulation for 1 hr, the following gases were tested for 15 min: Group I, 95% air + 5% CO2 (FiO2 = 0.21, n = 5); Group II, 10% O2 + 5% CO2 + 85% N2 (FiO2 = 0.1, n = 5); and Group III, 95% N2 + 5% CO2 (FiO2 = 0, n = 5). Equilibrated PaO2 values after challenge with these gases for 15 min were as follows: Group I: 89.6 +/- 3.7, Group II: 53.8 +/- 1.4, Group III: 25.6 +/- 2.0 mmHg (p < 0.01 between Groups I and II, I and III, II and III; p < 0.01 vs. prehypoxic PaO2 values in all groups). PaO2 values returned to the previous level within 15 min after return to the standard gas mixture (95% O2 + 5% CO2) supply. This system provided stable cardiopulmonary bypass in rats for at least 2 hr and may be useful for investigation of ischemia-reperfusion injury.     

The low-molecular-weight phosphotyrosine protein phosphatase, when overexpressed, reduces the mitogenic response to macrophage colony-stimulating factor and tyrosine phosphorylation of its receptor

Inert gases at raised pressure exert anaesthetic effects. It is assumed that anaesthesia by the inert gases is fundamentally similar to anaesthesia produced by general anaesthetics. However, do general anaesthetics bind directly to proteins or influence activity by indirectly perturbing membrane lipids still remains a major question. Although the pressure required to achieve anaesthesia with inert gases has been suggested to exert potentially some pressure antagonism per se, this has not been studied yet to our knowledge. We investigated this possibility using nitrogen, argon, and nitrous oxide. Whatever the narcotic agent used, our results showed that the pressure of narcotic required to induce anaesthetic effects increased, as compression rate increased, in a sigmoid fashion rather than in a linear fashion. Evidence for sigmo?dal responses vs. linear responses depended of the narcotic potency of the anaesthetic agent used (nitrogen: r2=0.973 vs. r2=0.941; argon: r2=0. 971 vs. r2=0.866; nitrous oxide: r2=0.995 vs. r2=0.879). Since a linear antagonism is predicted by lipid theories, we think it likely that these findings indicate that inert gases bind to a modulatory site of a protein receptor and act as allosteric modulators. Since other workers provided evidence for binding processes using volatile anaesthetics, the present findings could indicate that all classes of general anaesthetics, including inert gases, could act by binding directly to proteins rather than by dissolving in some lipids of the cellular membrane.     

System for cleaning blast-furnace gas in the blast-furnace shop at the VSZh Koshitse combine

Experience has shown that the dust content of the gases leaving a blast furnace can be cut by 4 mg/m³ by using a simple and reliable gas-cleaning system that includes a dust catcher, wet scrubber, Venturi tues, valve group, and water separator. A wet-type gas-cleaning system can remove up to 60% of the zinc and lead in the flue gases of blast furnaces operated on a charge having a high concentration of nonferrous metals. __________ Translated from Metallurg, No. 7, pp. 52–54, July, 2006.     

钢铁厂高能效利用副产煤气的可行途径

钢铁厂在生产过程中,副产了大量可燃煤气。副产煤气热值范围在3～20MJ/Nm3,所含的热量可被利用,如:电厂、焦炉、热风炉、热轧厂等所需燃料,可用副产煤气部分替代天然气,减少煤气放散,降低公司的能耗成本和环境污染。使用副产煤气虽能得益却也面临难题。副产煤气的产量和成分取决于生产和工艺状况,煤气用户必须随之调整其操作。用气设备的启停操作改变了煤气用量,造成煤气管网压力波动,副产煤气成分变化则会引起热值波动,一旦管网压力波动或成分改变,将对管网上用气单元的燃烧过程产生不利影响。针对副产煤气利用的复杂情况,AMB、AMEH和BFI公司开发了高能效利用副产煤气的途径,应用于部分钢铁厂,如:改善煤气管网压力和流量分布的技术,具备供需分布显示和预报功能的煤气管理系统。介绍了煤气管网压力波动控制以及副产煤气利用的结果和经验。     

Smelting‐Reduction Export Gas as Syngas in the Chemical Industry

Export gases from iron‐making processes are typically used as an energy source for heat and power generation within the iron and steel industry, although their calorific value is comparatively low. The fact that COREX® and FINEX® smelting‐reduction export gases typically consist of the major syngas‐components CO and H₂ (approx. 50% of gas composition), makes them attractive for utilization in the direct reduction of iron ores and in the chemical synthesis industry. This paper will discuss the required process steps for converting smelting‐reduction export gases into synthesis gas (syngas) using the example of methanol production. The calculated CO₂‐balance shows promising results for chemical utilization of COREX® export gas compared to energy utilization in conventional or combined power plants.