Triboelectric charging behavior of wood particles during pellet handling processes

Electrostatic charges accumulated on wood particles through triboelectrification during their transportation and handling processes can cause hazardous electrical discharge which may further trigger dust explosion. In this work, tribo-charging behavior of different kinds of wood particles was investigated by a vibrating plate charging method. It was found that reduction in the work function difference between contact bodies might contribute to the reduction of tribo-charge generation, while the reduction of electrical resistivity of wood pellets could effectively accelerate the charge dissipation. As the particle size decreases, accumulated charges increase significantly. In contrast, higher moisture content of wood particles leads to lower charge accumulation due to an accelerated charge dissipation rate. Tribo-charging behaviors of white pellets, torrefied pellet, steam treated pellets and dark pellets have also been investigated. Compared to the white pellets, they all have shown a reduction on charge accumulation to some extent. However, results suggested that all of them have nearly equivalent tribo-charge density as coal and wheat grains used as references in this study.     

粉料无尘装车技术及其在电除尘器、大布袋除尘器输灰系统中的应用

传统电除尘器、大布袋除尘器输灰系统存在工艺繁杂、能耗大、输送速度慢、系统难于维护及二次扬尘问题,电除尘器、大布袋除尘器输灰系统采用粉料无尘装车技术可有效简化工艺、提高生产速度和系统运行、维护可靠性,很大程度减少能耗并彻底根除二次扬尘。     

粉体气力输运中的静电问题研究

粉体在气力输运过程中会产生静电危害，首先要分析粉体产生静电的物理机制即着重研究：粉体气力输运中的静电现象与粉体和管路的几何、物理性质及输运的技术参数之间的关系；在对其中的某些因素如：输运气流流速、质量流量、粉体材料、粉体粒度等进行实验的基础上，总结出这些因素影响起电的规律。在测试技术方面，提出了一种新的、非接触式的利用静电感应原理测量粉体电量的方法，并与计算机结合，构成一个完整的测量系统。此法具有对工业粉体气力输运过程中的静电起电做连续、非接触在线测量的可行性。     

静电增强纤维层过滤技术的研究

对静电增强纤维层过滤进行理论及实验研究。得出纤维层在非稳态状态下,考虑三种作用机理时的效率式,并利用模型系统进行实验研究,对各种影响因素加以分析     

高电阻率收尘极板的实验研究

用电阻率较高的非金属材料制作电收尘器的收尘极板收尘,对于比电阻低于10~4Ω·cm的烟尘,能有效地克服积尘的跳跃式二次飞扬。对于比电阻为10~8Ω·cm左右的氧化铝粉尘,在工业现场实验,收尘效率达98.5％;对于比电阻为10~(13)Ω·cm左右的莹石粉尘,采用比电阻为10~(10)Ω·cm左右的混凝土极板,实验室实验,电晕电流正常,未观察到反电晕现象,推断存在“受抑制”的尘层间隙放电。     

双极不对称预荷电静电增强过滤除尘技术的应用

双极不对称预荷电静电增强过滤除尘技术,是国家\"九五\"科技攻关课题所取得的成果之一,该技术采用双极不对称荷电增强方式,将普通静电增强效果与粉尘凝并机能有机地结合在一起,既提高了过滤除尘器的收尘效率,尤其是呼吸性粉尘的效率,同时又极大地改善了滤料粉尘层的结构,可显著地降低过滤阻力增值,节约运行能耗.笔者研究的该技术应用于焊接车间的焊接烟尘的治理上,取得了良好的效果.现场测试表明,该技术对焊接烟尘的滤除效率提高了3%,尤其对微细粉尘效果显著,2 μm粉尘穿透率相对下降了47%.采用超细滑石粉高粉尘负荷测试结果表明,过滤阻力增值降低达30%,清灰效果明显改善.     

Test methodology for determining the incendiary nature and electrostatic discharge characteristics of plastic surfaces

This experimental study was originally designed to quantify the electrostatic characteristics of offshore grade fiberglass reinforced plastic (FRP) pipes [Dastidar, A. G., Dahn, C. J., Cole, B. W., & Lo, K. H. (2005a). Electrostatic characteristics of FRP pipes. In Fourth international conference on composite materials for offshore operation, Houston, TX, Oct 4–6, 2005]. Discharge energies were measured from the sample surfaces for each test condition after an aggressive corona charging of up to −40 kV. While the measured values of total discharge energy were relatively high for some samples, the energy in the first peak was significantly lower. The first peak energy is thought to be the most significant measure in establishing the potential for incendive events.

To further quantify the incendive potential of discharges from FRP pipes, a unique test method was developed [Dastidar, A. G., Dahn, C. J., Cole, B. W., & Lo, K. H., (2005b). Incendiary nature and electrostatic discharge characteristics of FRP pipes. In Fourth international conference on composite materials for offshore operation, Houston, TX, Oct 4–6, 2005]. The methodology has been expanded to include other FRP components. This paper describes the test method and the test results obtained for testing several FRP structures and materials (pipes, grill work, railing etc.). The significance of the experimental results to industry is also discussed.     

工业雷管意外起爆的防范研究

工业雷管在生产、贮运、使用过程中存在意外发火或爆炸事故。为了防止这种突然事件和避免带来的伤害与损失，笔者就可能导致意外起爆的各种原因进行了分析，提出了各种相应的防范措施和意见     

改性氢氧化钙粉体的研制及其特性

介绍了作为氯气清除剂的粉体应具有的特性,并对粉体的研制方法进行了简单叙述。同时,对改性氢氧化钙粉体特性作了详细介绍。不难看出,研制的改性氢氧化钙粉体具有高度活性,与氯气捕消器配合使用,将成为氯气泄漏时的抢险措施     

普通窗玻璃热破裂行为研究

运用微裂纹和热应力理论,根据建立的火灾中窗玻璃传热模型,从理论和实验上,系统地探讨了窗玻璃热破裂机理及其主要影响因素,并建立了一种预测窗玻璃热破裂 时间的方法。     

静电除尘净化球团竖炉烟气技术研究

介绍了球团竖炉的烟尘排放特性,分析研究了影响静电除尘器工作性能的主要因素,总结了静电除尘改造工程中技术改进经验和运行管理所取得的经验。     

典型静电放电火花点燃危险性评价方法研究

通过研究典型静电放电火花的实际点燃能力,对实际生产工艺工程中的静电放电火花的点燃危险性进行定量评价.静电放电火花的放电相当能量、放电火花空间分布范围和放电火花持续时间,决定了静电放电火花实际点燃可燃物的可能性大小,因此不同类型的静电放电火花点燃可燃物的差异性很大.根据数据序列理论分析,引入静电放电火花点火源序列和可燃物危险性序列之间存在的关联性,反映了静电放电火花点燃可燃物的危险程度,可用于对静电放电火花的实际点燃危险性进行量化评价.对聚烯烃粉体生产工艺过程中典型和频发性的静电放电火花的点燃危险性进行了定量评价.     

Relationship between electric spark sensitivity and activation energy of the thermal decomposition of nitramines for safety measures in industrial processes

This study presents a new simple correlation between electric spark sensitivity of nitramines and their activation energies of thermolysis, which are important for safety measures in industrial processes. The new correlation can help to elucidate the mechanism of initiation of energetic materials by electric spark. It can be used to predict the magnitude of electric spark sensitivity of new nitramines, which is difficult to measure. The methodology assumes that electric spark sensitivity of a nitramine with general formula C_aH_bN_cO_d can be expressed as a function of its activation energy of thermal decomposition as well as optimized elemental composition and the contribution of specific molecular structural parameters. The new correlation has the root mean square and the average deviations of 1.37 and 1.09 J, respectively, for 21 nitramines with different molecular structures. The proposed new method is also tested for 16 nitramines so that there is no experimental data of electrostatic sensitivity for them.     

Incendiary characteristics of electrostatic discharge for dust and gas explosion

Paying attention to the ignition potentiality of static electricity, the relation between the discharge characteristics and the ignition of a dust cloud and the gas produced was studied, applying an electrical power supply of which the electrical circuit is adjustable. The effect of ignition characteristics on dust and gas explosions was investigated. The results of the study indicate that the probability of an explosion is influenced by the minimum ignition energy, spark duration time, feeding rate of ignition energy, circuit capacitance, ignition voltage, etc.     

Electrostatic ignition of sensitive flammable mixtures: Is charge generation due to bubble bursting in aqueous solutions a credible hazard?

Experiments have been conducted to gain insight into the credibility of sparging aqueous solutions as an electrostatic ignition hazard for sensitive hydrogen/air or fuel/oxygen mixtures (Minimum Ignition Energies of ∼0.017 mJ and ∼0.002 mJ, respectively, compared to ∼0.25 mJ for hydrocarbon/air mixtures). Tests performed in a 0.5 m³ ullage produced electric field strengths between 125 and 560 V m⁻¹ for air flows of 5–60 l min⁻¹, respectively, comprised of 2–4 mm diameter bubbles. Field strength can be related to the space charge and fitting to an exponential accumulation curve enabled the charge generation rate from the air flows to be estimated. This was observed to be directly proportional to the air flow and its magnitude was consistent with literature data for bubble bursts. The charge accumulation observed at laboratory scale would not be a cause for concern. On the basis of a simple model, the charge accumulation in a 27 m³ ullage was predicted for a range of air flows. It is apparent from such calculations that ignition of hydrocarbon/air mixtures would not be expected. However, it would seem possible that field strengths might be sufficient to cause a risk of incendive spark or corona discharges in moderately sized vessels with sensitive flammable mixtures.     

带电细水雾的灭火实验研究

利用静电感应原理,设计了使细水雾强制带电的感应荷电装置,进行了带电细水雾的灭火实验研究。为研究带电细水雾的灭火效率,在受限空间内,采用小尺度实验方法,通过改变电压的极性和大小、针-环状电极的半径及其距伞罩电极之间的距离,分析对灭火时间和热电偶温度变化的影响。结果表明:带电细水雾比普通细水雾能更迅速地降低火焰温度、熄灭火焰,荷负电的细水雾比荷正电的细水雾具有更好的抑制效果,随着电压的增大、针-环状电极半径及两电极间距的减小,灭火效能提高,熄灭时间减少。