炼钢过程底吹气体的冶炼效果对比

 基于炼钢过程底吹气体热力学及动力学进行分析,研究了底吹氧气、二氧化碳、氩气、氮气的冶炼效果。研究结果发现,氩气或氮气不与熔池元素反应,底吹时熔池温度基本不变,钢中氮质量分数较高;底吹氧气或二氧化碳时,脱碳速率和钢中氮、氢质量分数基本相同,熔池温度升高了162和45 ℃。同时发现,与底吹氧气相比,二氧化碳可减少炼钢烟尘量,炉渣中[w((TFe))]降低2.50%,[w((O))]降低90.2%。     

新产品新技术

韩发现可提升EV锂电池能量密度的新方法近日,韩国研究人员发现,锂空气电池的性能与二氧化碳的含量有较大关联。相关论文已发表于《美国化学学会期刊》上。研究人员认为,电池中的Li2CO3根据锂空气电池中电解质的介电性能(dielectric properties),能够选择性地作为放电反应的最终产物。此外,他们还验证了Li2CO3在锂-氧气/二氧化碳电池循环中能够发生可逆反应。     

平顶山旅游气候资源分析及评价

利用平项山1971-2000年5个气候代表站(汝州、鲁山、宝丰、郏县、叶县)30年气候整编资料,结合人体舒适度指数对平顶山旅游气候资源优势进行综合分析及评价.认为平顶山旅游气候适宜期长达7个月.其中4-5月、9-10月为最舒适月,可根据不同季节开展特色旅游.     

矿井密闭空间中人体呼吸商计算

为深入研究矿用密闭空间的生命保障技术,4名实验人员在实验舱内分别进行了7组密闭空间人体生存实验,得出了人体在不同活动强度状态下的耗氧量和二氧化碳产生量,并计算了人体在密闭空间中生存的呼吸商.     

碳材料在锂-氧气/锂-二氧化碳电池中的应用综述

综述了碳材料在锂-氧气电池和锂-二氧化碳电池中的应用,包括商业碳材料、碳纳米材料、杂原子修饰的碳材料、金属及其氧化物修饰的碳材料和生物质衍生碳材料,系统归纳了采用碳材料作为空气阴极的锂-氧气电池和锂-二氧化碳电池性能提升的原因,为未来设计高性能的锂-氧气和锂-二氧化碳电池用碳材料提供了指导.     

AS脱硫工艺影响因素分析及优化

分析了AS脱硫工艺的影响因素.结合宣钢焦化厂的焦炉煤气脱硫工艺,采取了降低吸收温度,增加洗涤液流量,提高脱酸贫液挥发氨含量,降低脱酸贫液二氧化碳、固定氨含量,降低脱硫富液中二氧化碳含量,提高硫酸系统的开工率和转化率等措施,实现了操作参数的优化,净煤气H2S含量降低到0.3 g/m3以下,硫酸收率达到0.5％,硫酸尾气中SO2含量远低于国家标准.     

高温空气对燃烧回流区流动影响的数值模拟

通过建立圆管状燃烧室内甲烷气体燃烧的数学模型,对燃烧室回流区的温度场、速度场、流场以及甲烷、氧气、二氧化碳以及氮氧化合物的质量分数进行了数值模拟.通过改变入口高温空气的预热温度,数值模拟了以上变量的分布规律.研究结果表明:提高空气的预热温度,燃烧室内的反应进行越彻底,温度分布更均匀.研究结果对燃烧室的设计和燃烧室工况分析具有指导意义,所建立的数学模型为燃烧室几何及结构设计和燃烧过程操作中进行定量分析的有效手段.     

采用二氧化钛光催化降解气相甲苯的研究

采用浸渍涂布法制备以玻璃纤维布为载体的TiO2光催化剂,通过对连续流中光催氧化降解气相甲苯过程的研究,考察了甲苯进口质量浓度、相对湿度、氧气体积分数对甲苯的光催化降解效率影响。结果表明,相对湿度和氧气体积分数是影响气相甲苯降解的主要因素。     

炉顶煤气循环氧气高炉一维气固换热与反应动力学模型

结合风口回旋区燃烧和炉外煤气预热、脱除和循环的平衡关系,建立了氧气高炉一维气固换热与反应动力学模型,并采用传统高炉的运行和解剖数据对模型进行了验证分析.通过模型研究了氧气含量和上部循环煤气流量对氧气高炉炉内过程变量的影响规律.结果表明:氧气含量偏低和上部循环煤气流量不足时,会降低铁矿石还原效果,炉渣内出现大量未还原铁氧化物;氧气含量和上部循环煤气流量的提高可以有效提高炉内CO含量和铁矿石还原速度,但提高上部循环煤气流量会大幅提升炉顶煤气温度,增大热量损失.与传统高炉相比,氧气高炉内CO含量提高1.0~1.5倍,炉内气体还原性更强;铁矿石还原完成位置提高1.49 m,全炉还原反应速度更快;直接还原度降低55.2%~79.2%,炉内直接还原反应消耗的碳量更少.      

废塑料与煤粉升温过程中的燃烧特性

试验研究废塑料燃烧特性。在空气和氧气的不同条件下,研究了不同品种废塑料颗粒和对比煤粉的燃烧特性。结果表明：在氧气条件下,不同品种废塑料升温时尾气中CO含量明显升高的温度都比在空气中的低30℃,CO2含量比在空气中的显著升高;在空气或氧气同一条件下,废塑料的CO2最大含量都比煤粉大幅提高,废塑料完成燃烧的温度比煤粉的低300~500℃。     

热带海洋大气环境冷轧钢板锈蚀规律

 海洋大气环境中影响冷轧钢板锈蚀的主要因素为温度、相对湿度和Cl-浓度。为了研究热带海洋大气环境下环境因素对冷轧钢板在仓库中储存起锈时间的影响，以温度、相对湿度和Cl-浓度等环境因素为变量，在室内模拟装置进行了冷轧钢板锈蚀观测试验；同时，在钢铁厂冷轧成品库房进行了冷轧钢板挂样锈蚀观测试验。结果表明，室内模拟试验和现场试验结果一致性很好，可以通过室内模拟试验研究冷轧钢板在库房中的锈蚀特征和规律；温度为20～30 ℃时，冷轧钢板起锈时间与大气环境相对湿度之间呈线性关系；温度为35～45 ℃时，冷轧钢板起锈时间与大气环境相对湿度之间呈指数关系；冷轧钢板起锈的临界相对湿度随温度升高而降低。     

基于综合智能模型的碳钢大气腐蚀重要变量提取和依赖关系挖掘

针对碳钢在大气腐蚀过程中影响变量多且作用机制复杂的问题,提出一种基于综合智能模型的重要变量挖掘框架,利用该框架可以挖掘影响碳钢早期大气腐蚀的重要环境变量及其对腐蚀电偶电流产生的影响.本文通过大气腐蚀监测仪（ACM）收集了我国5个试验站点的大气腐蚀数据,首先,构建了随机森林（RF）、梯度提升回归树（GBRT）和BP神经网络（BPNN）三种机器学习模型;其次,利用多模型集成重要变量选择算法（MEIVS）量化环境变量的重要性并提取影响碳钢早期大气腐蚀的重要环境变量;最后,绘制了环境变量与腐蚀电偶电流的局部依赖曲线（PDP）.仿真结果显示,MEIVS算法挖掘出的重要环境变量更符合大气腐蚀的先验规律;PDP与MEIVS算法的结论具有很好的一致性,重要环境变量对应的PDP的变化幅度大,且PDP的变化趋势能够反映环境变量对腐蚀电偶电流的影响.     

Internal audit function can improve health care delivery

This investigation was designed to determine the degree of relationship among five climatological and five behavioral variables among institutionalized profoundly retarded males. Target behavior of 50 PMR males was correlated with changes in barometric pressure, indoor and outdoor temperature, and indoor and outdoor relative humidity. Significant correlations were obtained between changes in barometric pressure and changes in the on-dormitory ambient noise level. It was concluded that the data provided some degree of support for the biometeorological position, which purports a relationship between certain kinds of behavior and climatological changes.     

Early markers of major adverse events in children after cardiac operations

OBJECTIVES: The purpose of this study was to determine the physiologic variables that predict major adverse events in children in the intensive care unit after cardiac operations. METHODS: A cohort observational study was conducted. At the time of admission to the intensive care unit and 4, 8, 12, and 24 hours later the following variables were recorded: mean arterial pressure, heart rate, cardiac index, oxygen delivery, mixed venous oxygen saturation, base deficit, blood lactate, gastric intramucosal pH, carbon dioxide difference (the difference between arterial carbon dioxide tension and gastric intraluminal carbon dioxide tension), and toe-core temperature gradient. Major adverse events were prospectively identified as cardiac arrest, need for emergency chest opening, development of multiple organ failure, and death. RESULTS: Ninety children were included in the study; 12 had major adverse events and there were 4 deaths. Blood lactate level, mean arterial pressure, and duration of cardiopulmonary bypass were the only significant, independent predictors of major adverse events when measured at the time of admission to the intensive care unit. The odds ratio (95% confidence intervals) for major adverse events if a lactate level was greater than 4.5 mmol/L was 5.1 (1.2 to 21.1), for admission hypotension 2.3 (0.5 to 9.8), and for a cardiopulmonary bypass time greater than 150 minutes 13.7 (3.3 to 57.2). Four hours after admission lactate and carbon dioxide difference, and 8 hours after admission lactate and base deficit, were independently significant predictors. The odds ratios for major adverse events if the blood lactate level was greater than 4 mmol/L at 4 and 8 hours were 8.3 (1.8 to 38.4) and 9.3 (1.9 to 44.3), respectively. At no time in the first 24 hours were cardiac output, oxygen delivery, mixed venous oxygen saturation, toe-core temperature gradient, or heart rate significant predictors of major adverse events. CONCLUSIONS: In the context of our current treatment strategies, the duration of cardiopulmonary bypass and blood lactate level, measured in the early postoperative period, were the best predictors of impending major adverse events.     

吸附塔工艺参数对活性炭烧结烟气脱硫的影响

活性炭可高效脱除烧结烟气中的SO₂,但同时受到吸附塔工艺参数的制约。为了揭示工艺参数对脱硫率的影响规律,采用控制变量法,通过模拟烧结烟气进行活性炭脱硫研究。结果表明,空速、烟气湿度、含氧量和活性炭床温度对脱硫影响较大,活性炭粒度对脱硫率影响较小;降低空速、活性炭床温度及活性炭粒度,均有利于SO₂物理吸附进而促进脱硫率提高;烟气湿度和含氧量的增加,有利于SO₂的化学吸附进而提高脱硫率,但湿度大于12%时,水蒸气会在活性炭上聚集形成水膜而导致脱硫率下降。     

Thunderstorm associated asthma: a detailed analysis of environmental factors

OBJECTIVES: To seek associations between meteorological factors, concentrations of air pollutants or pollen, and an asthma epidemic which occurred in London on 24 and 25 June 1994 after a thunderstorm. DESIGN: Retrospective study of patients' accident and emergency department records, with bivariate and multivariate analysis of environmental factors and data collection for the two months surrounding the epidemic. SETTING: The accident and emergency department of St Mary's Hospital in west central London. SUBJECTS: 148 patients presenting with asthma between 1 June and 31 July 1994, of whom 40 presented in the 24 hours after the storm. RESULTS: The asthma epidemic was significantly associated with a drop in air temperature six hours previously and a high grass pollen concentration nine hours previously. Non-epidemic asthma was significantly associated with lightning strikes, increase in humidity or sulphur dioxide concentration, a drop in temperature or high rainfall the previous day, and a decrease in maximum air pressure or changes in grass pollen counts over the previous two days. CONCLUSIONS: New episodes of asthma during the epidemic on 24 and 25 June 1994 were associated with a fall in air temperature and a rise in grass pollen concentration. Non-epidemic asthma was significantly associated with a greater number of environmental changes. This may indicate that the patients with thunderstorm associated asthma were a separate population, sensitive to different environmental stimuli.     

氧气高炉回旋区内煤粉燃烧行为的三维数值模拟研究

炉顶煤气循环氧气高炉是一种全新的炼铁新工艺,它可以有效提高煤比、减少CO₂的排放.但是其复杂的燃烧条件将使煤粉在回旋区内的燃烧及高炉下部的行为发生很大变化.为了了解氧气高炉炼铁新工艺条件下喷吹煤粉的复杂现象,建立了一个氧气高炉条件下的氧煤枪-直吹管-风口-回旋区-焦炭床的三维数学模型,研究了氧气高炉下部的温度场、浓度场及煤粉的流动和燃烧特性.模拟结果表明,氧气高炉条件下的回旋区温度显著升高、高温区面积扩大,CO₂含量提高,焦炭床内CO含量显著增加.此外,与传统高炉相比,氧气高炉回旋区表面的煤粉燃尽率增加了10.24%.      

CO2顶吹比例对转炉终点控制的影响

结合CO₂的高温反应特性,针对性地制定了CO₂冶炼工艺,并对转炉顶吹CO₂比例对终点磷、氮和碳氧浓度积的影响进行了工业试验研究。结果表明:随着转炉冶炼前中期CO₂顶吹比例由4.84%逐渐提高到9.68%,转炉终点磷的质量分数先下降后基本不变,氮的质量分数逐渐下降,碳氧浓度积与渣中TFe变化趋势基本相同,均为先降低后增加,对于不同指标最佳顶吹CO₂比例不同。试验转炉终点磷、氮的质量分数、碳氧浓度积与渣中TFe均下降,下降比例最高分别为20.4%、34.3%、12.92%和8.89%。      

Catalytic Incineration of Acrylonitrile with Platinum Supported on Al2O3

The catalytic decomposition of acrylonitrile with catalysts was investigated in a bench scale fixed bed reactor in this study. Two catalysts, including Pt/γ-Al2O3 and Cr2O3/α-Al2O3, were tested to study their catalytic activity in the complete oxidation of acrylonitrile. The results show that the Pt/γ-Al2O3 catalyst has better performance. The operating parameters such as operating temperature, acrylonitrile concentration, space velocity, and oxygen concentration were conducted in a series of experiments on the Pt/γ-Al2O3 catalyst. The results indicate that decomposition efficiency increases with temperature and oxygen concentration and decreases with the increases of space velocity and acrylonitrile concentration. With a regression model, the operating temperature is the most effective parameter on the decomposition of acrylonitrile. Carbon dioxide is the dominant product and carbon monoxide is an insignificant product of the decomposition of acrylonitrile. Material balance on carbon is good for the experiments. According to the BET and elemental analyzer analysis, major factors that cause the deactivation effect may result from nitrogen poisoning and carbon masking on the catalyst surface, especially at lower temperatures.     

Intrarenal nitric oxide activity and pressure natriuresis in anesthetized dogs

In the course of an ongoing cohort study on constitutional and occupational risk factors for the development of irritant hand dermatitis in hairdressing apprentices, an increased prevalence of irritant skin changes was noted in a subgroup examined during particularly cold winter months. Prompted by this observation, the importance of several meteorological factors (day means of temperature, relative and absolute humidity) was assessed in extensive statistical analyses based on data of 742 participants, supplemented by meteorological information obtained from the German Meteorological Service (DWD). There were significant associations of existing hand dermatitis with low temperature and low absolute humidity (Mann-Whitney U-test, P < 0.0001), but not with relative humidity (P = 0.38). Logistic regression analysis, including known determinants of irritant hand dermatitis in this setting, showed that low temperature and low relative humidity tended to be risk factors (OR = 1.66 and 1.57, respectively, for the lower quartiles, P = 0.07 in both cases), and confirmed that absolute humidity significantly influenced the occurrence of irritant hand dermatitis (OR = 2.06 for < 4.8 mg/L, P < 0.01). Thus, these environmental factors must be regarded as possible confounders in the analysis of future epidemiological studies on irritant hand dermatitis and should be considered in multifactorial analyses.