Microwave thermal remediation of crude oil contaminated soil enhanced by carbon fiber

Thermal remediation of the soil contaminated with crude oil using microwave heating enhanced by carbon fiber (CF) was explored. The contaminated soil was treated with 2.45 GHz microwave, and CF was added to improve the conversion of microwave energy into thermal energy to heat the soil. During microwave heating, the oil contaminant was removed from the soil matrix and recovered by a condensation system of ice-salt bath. The experimental results indicated that CF could e ciently enhance the microwave heating of soil even with relatively low-dose. With 0.1 wt.% CF, the soil could be heated to approximately 700°C within 4 min using 800 W of microwave irradiation. Correspondingly, the contaminated soil could be highly cleaned up in a short time. Investigation of oil recovery showed that, during the remediation process, oil contaminant in the soil could be e ciently recovered without causing significant secondary pollution.     

2008年北京采暖开始前后大气颗粒物化学成分及来源研究

为了系统反映北京采暖开始前后大气颗粒物的特征,于2008年10月底到12月初在北京北三环内城区使用分级式撞击采样仪进行了大气颗粒物采样,并用质子激发X射线荧光分析(PIXE)方法对其中16种化学元素浓度进行了分析.结果表明,采暖开始后16种元素总浓度较采暖期前增长3%,As、Cu在采暖期间的浓度增幅在30%以上,采暖开始后细粒子中Pb浓度增长为27%.富集因子分析结果表明,Cu、As、Pb等元素细粒子的富集因子比1999年同期有明显减小,说明北京近年来实行的环保措施较为有效.     

升-降温全过程中约束钢梁的有限元与试验分析

以轴向支撑连接方式,利用自制的加热炉对约束钢梁进行了升—降温全过程的试验研究。重点研究了钢梁的跨中挠度随温度变化的规律,以及梁端不同轴向支撑刚度和钢柱不同轴压比条件下约束钢梁的屈曲模式及其梁端轴向支撑的破坏形态。基于ANSYS有限元软件,采用温度场和结构耦合中的间接法,对升-降温全过程中的约束钢梁进行了有限元分析。数值计算结果与试验结果吻合较好,验证了有限元模型和参数设置的合理性。根据对比分析,讨论了我国现行钢结构防火技术规范中存在的关键问题,特别提出了钢结构抗火设计应有的内涵,为钢结构抗火研究提供了新的思路。     

电阻加热修复佳乐麝香污染土壤的工艺优化

佳乐麝香(Galaxolide,HHCB)是土壤中的一种新兴的半挥发性有机污染物,具有较高的毒性,需修复治理。电阻加热技术(electrical resistance heating,ERH)因加热均匀、效果好,逐渐被应用于有机污染土壤修复工程。采用自主研制的电阻加热装置,研究了加热过程中电场强度、土壤含水率和土壤粒径等因素对土壤HHCB去除效果的影响,并采用响应面法对工艺参数进行了优化。结果表明,土壤 HHCB去除率随电场强度和含水率的增大先增加后减小,随土壤粒径的增大而增大;在土壤含水率为40%、土壤粒径1~2 mm和电场强度12 V·cm⁻¹的条件下,加热6 h,HHCB去除效果最好,去除率达到了81.35%。通过响应曲面模拟优化得到的最佳工艺参数条件为,含水率39.07%、土壤粒径2.92 mm、电场强度12.64 V·cm⁻¹,在此条件下土壤HHCB的去除率为86.43%;在本实验条件下,3个因素对土壤HHCB去除率的影响为：含水率>土壤粒径>电场强度。本研究结果可为多环麝香污染土壤的修复提供参考。     

周转时间的延长对焦炉加热的影响及调整

周转时间的延长引起2#焦炉加热系统中温度、压力的改变,使现有的加热制度不能适应焦炉生产的需求.为制订合适的加热制度,通过对影响2#焦炉加热制度的各项因素的分析,确定了影响加热制度的主要原因,即标准火道(flame path)冷却温度的不合适和焦炉煤气(coal oven gas)横管两端压力低.在经过多次试验的基础上,对加热制度进行调整,制定了合适的加热制度,为2#焦炉在周转时间延长后的正常生产提供了有力的保障.     

Development and modification of permanent magnet brushed DC motor for hybrid photovoltaic-operated solar systems

A modified brushed permanent magnet DC (PMDC) motor has been developed and fabricated for a photovoltaic (PV)-operated solar systems. The conventional PMDC motor has been plagued with constraints, the most critical being ingestion of vapours of working fluid inside the rotor and stator, damaging the insulation of windings and forming a thin film of moisture between commutator and brushes. This flaw results into a very low mean time between failures of the motor. In the past, many attempts have been made where-in variety of seals to isolate the working fluid vapours from inner parts of motor have been tried out, but to no avail. Even Brushless DC motors have been designed in the past but their exorbitant cost makes the entire arrangement not viable economically. The modification attempted in this article overcomes the problem of working fluid ingestion inside the motor. It is found that mass flow rate of working fluid obtained at maximum peak sunshine hours is 17.5 l/min at 3030 rpm of motor driven by a PV module of 40 W at 16.20 V. This low-cost modified PMDC motor has been robust with high mean time between failures as no breakdown observed during 18 months of operation.     

电加热服装的研制

本文采用电加热原理,研制了一种加热服装,由背心、电池和加热载体三部分组成,可遥控操作不同的发热功率,全功率发热时间大于3h,衣内表面温度不低于50℃。     

Experimental study on CO and CO2 emissions from spontaneous heating of coals at varying temperatures and O2 concentrations

Laboratory experiments were conducted to investigate carbon monoxide (CO) and carbon dioxide (CO₂) emissions from spontaneous heating of three U.S. coal samples in an isothermal oven at temperatures between 50 and 110 °C. The oxygen (O₂) concentration of an oxygen/nitrogen (N₂) mixture flowing through the coal sample was 3, 5, 10, 15, and 21%, respectively. The temperature at the center of the coal sample was continuously monitored, while the CO, CO₂, and O₂ concentrations of the exit gas were continuously measured. The results indicate that the CO and CO₂ concentrations and the CO/CO₂ ratio increased when the initial temperature was increased. As the inlet O₂ concentration increased, the CO and CO₂ concentrations increased, while the CO/CO₂ ratios tended to converge to the same value. The ratio of CO/CO₂ was found to be independent of coal properties, approaching a constant value of 0.2. The maximum CO production rate correlated well with the maximum coal temperature rise. The apparent order of reaction for coal oxidation was estimated to be between 0.52 and 0.72. The experimental results in this study could be used for early detection and evaluation of a spontaneous heating in underground coal mines.     

吹苯塔塔底加热系统的改进和栅板固定

介绍了某厂吹苯塔生产过程中采用直接蒸气加热存在的问题,提出了加热系统的改进和使用方法。     

软质聚氨酯泡沫阴燃前期热解特性研究

采用DSC-TGA(差示扫描量热-热重分析)同步热分析仪对软质聚氨酯泡沫(聚氨酯软泡)在不同氧气体积分数(0、10％、30％、50％)和不同加热速率(10 K/min、20 K/min、50 K/min)下热解到800℃的过程及其对阴燃的影响进行了研究.结果表明,当氧气体积分数介于10％ ～ 50％时,聚氨酯软泡热失重DTG曲线只有1个峰;当氧气体积分数降低到10％时,DTG曲线开始逐渐分离为2个峰;当氧气体积分数降为0(即氮气气氛)时,DTG曲线已经明显分为2个峰.这表明氧气体积分数对聚氨酯软泡热解特性具有重要作用.氧气体积分数和加热速率降低均对聚氨酯软泡的热解有抑制作用,均能减小阴燃传播速率和向明火转化的可能性.加热速率降低主要是延长了聚氨酯软泡的热解周期,从而减小了热解可燃气体积分数和放热速率.氧气体积分数降低对聚氨酯软泡热解的影响相对复杂的多:当氧气体积分数从10％降低到0时,主要提高了聚氨酯软泡的分解温度,而对热解速率影响不大;当氧气体积分数介于10％～50％时,氧气体积分数减小主要会降低聚氨酯软泡的热解速率、放热速率和放热量而对热解温度影响相对不大.氧气体积分数和加热速率降低抑制了多元醇的分解,而多元醇是聚氨酯软泡维持阴燃或向明火转化的主要物质及能量来源.