转炉双渣及铁水勾兑法冶炼高硅铁水(硅含量0.60%~1.50%)存在冶炼周期长、工序繁琐、煤气回收量少等弊端,制约了生产效率和经济效益的提升。为解决这一问题,通过工艺优化尝试采用单渣法冶炼技术,并配套多项关键控制措施。首先,灵活调整...转炉双渣及铁水勾兑法冶炼高硅铁水(硅含量0.60%~1.50%)存在冶炼周期长、工序繁琐、煤气回收量少等弊端,制约了生产效率和经济效益的提升。为解决这一问题,通过工艺优化尝试采用单渣法冶炼技术,并配套多项关键控制措施。首先,灵活调整转炉装入量,基于热平衡原理精确计算废钢加入量,确保冶炼过程温度稳定。其次,优化渣料加入方式,将第一批渣料加入量控制在总渣料的50%以下,并延迟至硅氧化末期、碳氧化初期加入,降低前期炉渣过氧化风险。在吹炼过程中,采用低枪位操作抑制喷溅,同时控制炉渣碱度在2.2~2.5范围内,减少渣量至合理水平,维持渣中MgO含量约8%。通过不留渣操作并预留少量白云石随时压制喷溅,利用返矿平衡多余热量,实现过程平稳控制。终点阶段将碳含量精准控制在0.055%~0.065%,既保障脱磷效果又避免过氧化。实践表明,与传统双渣法相比,单渣法冶炼钢铁料消耗降低5.37 kg/t,煤气回收量增加10 m 3/t,冶炼周期缩短5~7 min,综合成本节约14.68元/吨。该技术为高硅铁水冶炼提供了高效、低耗的新方案,具有显著的推广应用价值。展开更多
目的系统评价生物制剂治疗中重度斑块状银屑病的长期有效性。方法计算机检索PubMed、EMbase、Web of Science和The Cochrane Library数据库,搜集生物制剂治疗中重度斑块状银屑病的随机对照试验(RCT),检索时限均为建库至2021年5月。由2...目的系统评价生物制剂治疗中重度斑块状银屑病的长期有效性。方法计算机检索PubMed、EMbase、Web of Science和The Cochrane Library数据库,搜集生物制剂治疗中重度斑块状银屑病的随机对照试验(RCT),检索时限均为建库至2021年5月。由2名研究者独立筛选文献、提取资料并评价纳入研究的偏倚风险后,采用Stata 16.0软件进行网状Meta分析。结果共纳入26个RCT。网状Meta分析结果显示,纳入的11种生物制剂中,瑞莎珠单抗最有效,其次为比美吉珠单抗、布罗达单抗、古赛奇尤单抗、依奇珠单抗,再次为司库奇尤单抗、阿达木单抗、乌司奴单抗,最次为伊纳西普。结论当前证据显示,瑞莎珠单抗可作为斑块状银屑病患者治疗的首选药物。受纳入研究数量和质量的限制,上述结论尚待更多高质量研究予以验证。展开更多
In order to replace the conventional distributor, a novel asynchronous rotating air distributor, which can optimize the drying ability of fluidized bed and strengthen the drying performance of oil shale particles, is ...In order to replace the conventional distributor, a novel asynchronous rotating air distributor, which can optimize the drying ability of fluidized bed and strengthen the drying performance of oil shale particles, is creatively designed in this study. The rotating speed of the asynchronous rotating air distributor with an embedded center disk and an encircling disk is regulated to achieve the different air supply conditions. The impacts of different drying conditions on the drying characteristic of Wangqing oil shale particles are studied with the help of electronic scales. The dynamics of experimental data is analyzed with 9 common drying models. The results indicate that the particles distribution in fluidized bed can be improved and the drying time can be reduced by decreasing the rotating speed of the embedded center disk and increasing the rotating speed of the encircling disk. The drying process of oil shale particles involves a rising drying rate period, a constant drying rate period and a falling drying rate period. Regulating the air distributor rotating speed reasonably will accelerate the shift of particles from the rising drying rate period to the falling drying rate period directly. The two-term model fits properly the oil shale particles drying simulation among 9 drying models at different air supply conditions. Yet the air absorbed in the particles' pores is diffused along with the moisture evaporation, and a small amount of moisture remains on the wall of fluidized bed in each experiment, thus, the values of drying simulation are less than the experimental values.展开更多
Agglomerates formed in the fluidized bed were studied in this paper using the TEB atomization nozzle. The multi-sieving method was adopted to distinguish the size of original particles, nucleation agglomerates, cohere...Agglomerates formed in the fluidized bed were studied in this paper using the TEB atomization nozzle. The multi-sieving method was adopted to distinguish the size of original particles, nucleation agglomerates, coherence agglomerates, and paste agglomerates in order to successfully identify the different growth stages and select the region for coexistence of most stable heterogeneous agglomerates as the research object. A multi-channel conductance electrical circuit experimental device was developed in this study to measure the conductance signal, which was found to have a liner relationship with the moisture content inside the fluidized bed. By adjusting the sieve mesh openings to achieve the layered isolation of heterogeneous agglomerates, the conductance signal recovered slowly as a result of the agglomerates' fracture during the continuous fluidization process, so that particles and agglomerates moisture distribution measurements could be implemented. The device was used to measure the particles and agglomerates moisture distribution state in the heterogeneous coexistence region, when they were injected with liquid mass within the range of w i=2.8 kg to 4.4 kg. The results indicated that with the increase of liquid mass flow, the moisture content of coherence agglomerates also increased, but the moisture content of nucleation agglomerates was decreased, and that of the original particles was maintained at a relatively low level. When the experimental injection amount reached 4.4 kg, the moisture contained in coherence agglomerates could amount to 87.3%, accounting for a big percentage of moisture in the fluidized bed.展开更多
文摘转炉双渣及铁水勾兑法冶炼高硅铁水(硅含量0.60%~1.50%)存在冶炼周期长、工序繁琐、煤气回收量少等弊端,制约了生产效率和经济效益的提升。为解决这一问题,通过工艺优化尝试采用单渣法冶炼技术,并配套多项关键控制措施。首先,灵活调整转炉装入量,基于热平衡原理精确计算废钢加入量,确保冶炼过程温度稳定。其次,优化渣料加入方式,将第一批渣料加入量控制在总渣料的50%以下,并延迟至硅氧化末期、碳氧化初期加入,降低前期炉渣过氧化风险。在吹炼过程中,采用低枪位操作抑制喷溅,同时控制炉渣碱度在2.2~2.5范围内,减少渣量至合理水平,维持渣中MgO含量约8%。通过不留渣操作并预留少量白云石随时压制喷溅,利用返矿平衡多余热量,实现过程平稳控制。终点阶段将碳含量精准控制在0.055%~0.065%,既保障脱磷效果又避免过氧化。实践表明,与传统双渣法相比,单渣法冶炼钢铁料消耗降低5.37 kg/t,煤气回收量增加10 m 3/t,冶炼周期缩短5~7 min,综合成本节约14.68元/吨。该技术为高硅铁水冶炼提供了高效、低耗的新方案,具有显著的推广应用价值。
基金supported by the National Natural Science Foundation of China(Grant No.51276033,No.51541608)
文摘In order to replace the conventional distributor, a novel asynchronous rotating air distributor, which can optimize the drying ability of fluidized bed and strengthen the drying performance of oil shale particles, is creatively designed in this study. The rotating speed of the asynchronous rotating air distributor with an embedded center disk and an encircling disk is regulated to achieve the different air supply conditions. The impacts of different drying conditions on the drying characteristic of Wangqing oil shale particles are studied with the help of electronic scales. The dynamics of experimental data is analyzed with 9 common drying models. The results indicate that the particles distribution in fluidized bed can be improved and the drying time can be reduced by decreasing the rotating speed of the embedded center disk and increasing the rotating speed of the encircling disk. The drying process of oil shale particles involves a rising drying rate period, a constant drying rate period and a falling drying rate period. Regulating the air distributor rotating speed reasonably will accelerate the shift of particles from the rising drying rate period to the falling drying rate period directly. The two-term model fits properly the oil shale particles drying simulation among 9 drying models at different air supply conditions. Yet the air absorbed in the particles' pores is diffused along with the moisture evaporation, and a small amount of moisture remains on the wall of fluidized bed in each experiment, thus, the values of drying simulation are less than the experimental values.
基金supported by the National Natural Science Foundation of China(No.51276033)
文摘Agglomerates formed in the fluidized bed were studied in this paper using the TEB atomization nozzle. The multi-sieving method was adopted to distinguish the size of original particles, nucleation agglomerates, coherence agglomerates, and paste agglomerates in order to successfully identify the different growth stages and select the region for coexistence of most stable heterogeneous agglomerates as the research object. A multi-channel conductance electrical circuit experimental device was developed in this study to measure the conductance signal, which was found to have a liner relationship with the moisture content inside the fluidized bed. By adjusting the sieve mesh openings to achieve the layered isolation of heterogeneous agglomerates, the conductance signal recovered slowly as a result of the agglomerates' fracture during the continuous fluidization process, so that particles and agglomerates moisture distribution measurements could be implemented. The device was used to measure the particles and agglomerates moisture distribution state in the heterogeneous coexistence region, when they were injected with liquid mass within the range of w i=2.8 kg to 4.4 kg. The results indicated that with the increase of liquid mass flow, the moisture content of coherence agglomerates also increased, but the moisture content of nucleation agglomerates was decreased, and that of the original particles was maintained at a relatively low level. When the experimental injection amount reached 4.4 kg, the moisture contained in coherence agglomerates could amount to 87.3%, accounting for a big percentage of moisture in the fluidized bed.
