二垩英与资源回收-Ⅰ考虑到二垩英生成的资源与能量回收基础研究

目前在日本,存在大量工业垃圾,包括各种塑料制品,ASR(汽车破碎垃圾),含有毒PCB(多氯联苯)的110变压器和PVC(聚氯乙稀)制品等.而来自城市垃圾焚烧炉的废气含有大量能量.因此,在充分考虑环境、避免二垩英生成的同时,安全回收来自工业垃圾、城市和/或工业垃圾焚烧炉的资源和能量是个非常重要的课题,这也将对抑制CO2排放作出贡献.正确地阐明焚烧过程中二垩英的生成机理及详细研究含少量二垩英的焚烧废气在冷却过程中大量形成二垩英的临界温度是项很重要的工作.解决这个问题可有效实现资源和能量的回收.本报告介绍日本在二垩英排放方面目前采取的对策和存在的问题以及大阪大学为阻止二垩英生成所做的基础研究工作.     

Fundamental Study on Continuous Casting Process With Swirling Flow by Electromagnetic Force

Swirling flow in a submerged entry nozzle is effective on improving quality of casting block and casting speed in continuous casting of steel.A new method for swirling flow generation in the nozzle has been proposed by the authors,that is a rotating electromagnetic field is set up around a submerged entry nozzle(SEN)to induce swirling flow in it by Lorentz force.In this study,the magnetic field in molten steel in the submerged entry nozzle,the flow and temperature field in the SEN and mold in round,square billet and slab continuous casting process of steel are numerically studied.The model experiment of electromagnetic swirling continuous casting is also conducted with low melting point alloy.The commercial test for slab is undergoing.Results by numerical simulation and experiment show that the swirling flow by the optimum designed electromagnetic swirling generator can not only improve the distribution of flow and temperature in mold but also achieve the same effects generated by the swirling blade process.And,more effects on continuous casting process can be expected after this electromagnetic swirling process is optimized.     

钢圆坯连铸过程中渐开式电磁旋流水口数值模拟

提出了一种新的浸入式水口内产生旋流的方法.即在水口外施加可移动的旋转电磁场,非接触地形成钢液旋流.为进一步发挥旋流作用,采用渐开式水口,对圆坯连铸中浸入式水口及结晶器内钢液流场、温度场进行了三维数值模拟,并重点研究了水口渐开角度结合不同旋流强度对结晶器内流场及温度场的影响.研究结果表明,浸入式水口内磁场和旋流速度随着线圈电流强度的增加而增加.当电流强度为500 A,频率为50 Hz时.可产生最大为3 m/s左右的旋流速度.当水口采用同一渐开角度,随着旋流强度的增大,水口出流的冲击深度减小,上返流增强,弯月面温度提高.但当旋流强度增大到一定程度后,结晶器内弯月面附近温度变化不大.采用同一旋流强度,随着水口渐开角度的增加,结晶器内水口出口上方的上返流先增强后减弱,在渐开角度为60°时,上返流最强.同样,弯月面附近温度也是先提高后有所降低,在渐开角度为60°时,弯月面温度最高.水口渐开角度为60°,线圈电流350 A,频率为50 Hz时,在水口入口处施加0.5 m/s水平速度的人工偏流后,电磁旋流能对该偏流进行有效的抑制.     

Suppression of Effect of Uneven Velocity in Submerged Entry Nozzle in Round Billet Continuous Casting Process Using Electromagnetic Swirling Flow

Sliding gate control system is widely employed in continuous casting process of steel to control flow rate of molten steel.As molten steel passes through a sliding gate,uneven flow develops.This will cause asymmetrical distribution of flow and temperature field in mold consequently,formation of vortex near the nozzle and entrapment of CC powder into the molten steel.etc,which have negative effect on process productivity and product quality.To suppress the uneven flow,electromagnetic swirling flow has been proposed to impose on the flow in submerged entry nozzle below the sliding gate.In this study the uneven flow developed by incompletely open sliding gate and the suppression of this uneven flow using electromagnetic swirling flow are numerically studied in round billet continuous casting of steel process.The improvement of the flow and temperature filed in the submerged entry nozzle and mold are investigated.It is found that:The uneven velocity in nozzle can be suppressed by electromagnetic swirling flow,and the flow and temperature field in mold be improved obviously;With the increase of electromagnetic swirling intensity,the effect of uneven flow can be almost completely suppressed.     

二垩英与资源回收-Ⅲ燃烧过程二垩英生成热力学计算

进行相关热力学计算以研究高温燃烧过程二垩英生成的条件.计算得到:①在体系存在过剩氧即完全燃烧时不会产生二垩英;②当有固体碳沉积时也不会生成二垩英,因固体碳在热力学上比含二垩英的含碳物更稳定.另一方面,实际上即使在1 073 K完全燃烧条件下(即体系显著过剩氧)也有二垩英生成,原因是在实际燃烧炉中含碳微粒不可能完全烧尽.从热力学角度假设不发生碳沉积,计算得出二垩英在1 073 K高温和高CO/CO2比范围内会生成.实际考虑的条件放在燃烧炉内含碳微粒的周围.在有含碳微粒存在条件下,即使反应2CO→C+CO2(碳沉积)发生,C+CO2→2CO反应(CO生成;含碳微粒被CO2氧化)也会同时发生,导致在含碳微粒周围保持一个高的CO/CO2比,由此产生二垩英.假设在含碳微粒周围存在高CO/CO2比的异质位置,则认为二垩英会形成.     

二垩英与资源回收-Ⅱ燃烧过程二垩英抑制和生成基础研究

氯来源、种类和燃烧物中氯浓度对燃烧过程中二垩英生成有重要影响.在实验燃烧炉中研究1 073K温度下上述三种因素对燃烧过程二垩英生成的影响.二垩英生成浓度在相同氯源和种类条件下与燃烧物中氯含量几乎成正比,且受氯源明显影响.如有机氯化合物或无机氯化物.即使对无机氯化物,在有活性氯存在时也会生成高浓度二垩英,如由盐和面粉形成的水化物中的活性氯.     

Discussion of treatments for the kinetics of radical polymerization with primary radical termination

Without knowledge of the familiar geometric mean, the following equation was derived for the radical polymerization with primary radical termination under the condition that reaction between primary radicals is negligible: where both A and B are constants depending on various rate constants. This equation was mathematically and experimentally dealt with.     

Some unsymmetrical azo compounds as initiators in radical polymerization

2-Propylazodiphenylmethane (PAD), cyclohexylazodiphenylmethane (CAD), benzylazodiphenylmethane (BAD) and 1-phenylethylazodiphenylmethane (PEAD) were prepared. These materials decomposed through first order reactions. The ease of decomposition increased in the order: CAD < PAD < BAD < PEAD, the rate being insensitive to the change in solvent. The rate constant of decomposition of PEAD was about twice that for 2,2′-azobisisobutyronitrile and that for CAD was nearly equal to that of benzoylperoxide. The initiation efficiencies were about 0.1 for CAD and PAD, 0.2 for BAD and 0.45 for PEAD. Transfer of polymer radical to the above unsymmetrical azo compounds was not negligibly small.     

电磁旋流水口在钢圆坯连铸中的作用

机械式旋流水口连铸的工业试验结果表明:弯月面的钢液温度、稳定性以及铸坯的等轴晶率等能得到显著提高。但该工艺难以工业应用。本文作者提出了一种新的旋流连铸工艺,即利用水口外的旋转电磁场对钢液的洛伦兹力,使水口内钢液形成旋转流动。本研究通过磁场和流场的三维数值模拟,分析了电磁旋流装置结构对圆坯连铸过程中浸入式水口及结晶器内钢液速度的大小及分布的影响,并应用低熔点合金进行了实验验证。结果表明:非接触方式的电磁力可以有效地使钢液在浸入式水口内产生旋转流动。在同等条件下,圆形电磁旋流装置时钢液的速度分布最对称,速度值最大;改进马蹄形时的水口内流场分布与圆形的较为接近,比采用马蹄形时的更为对称,且速度值更大。在结晶器内,电磁旋流使钢液的冲击深度变小,上返流增强。这有利于温度的均匀化,提高弯月面的温度,以及促进夹杂物的上浮。考虑工业生产的操作方便问题,改进马蹄形电磁旋流装置比较适合生产实际。电磁旋流实验的结果验证了数值模拟的结果及计算方法的可靠性。     

Simulation on Effect of Divergent Angle of Submerged Entry Nozzle on Flow and Temperature Fields in Round Billet Mold in Electromagnetic Swirling Continuous Casting Process简

A new process for swirling flow generation in the submerged entry nozzle （SEN） in continuous casting process of steel was proposed. A rotating electromagnetic field was set up around the SEN to induce swirling flow by Lorentz force. The flow and temperature fields in the SEN and round billet mold with electromagnetic swirling were numerically simulated and then verified by the electromagnetic swirling model experiment of low melting point alloy. The effects of divergent angle of the SEN on the flow and temperature fields in mold with electromagnetic swirling were investigated. The electromagnetic swirling flow generator （EMSFG） could effectively induce swirling flow of molten steel in the SEN, which consequently improved greatly the flow and temperature fields in the mold. Below the nozzle outlet in mold, with the increase of divergent angle, the stream of bulk flow diverged more widely, the high temperature zone shifted up, and the temperature field became more uniform. Above the nozzle outlet in mold, with 350 A electromagnetic swirling, when the divergent angle of the SEN increased, the upward flow velocity and the meniscus temperature first increased and then decreased. With a divergent angle of 60~, the upward flow velocity and meniscus temperature reaced the largest value.