单侧受限浮力羽流对室内空气颗粒物沉积的影响

为探讨单侧受限浮力羽流作用下的颗粒物沉积特性,采用粉尘监测仪对单侧受限浮力羽流存在处和远离浮力羽流的室内空间中的不同粒径颗粒物浓度进行24 h连续监测,分析15种工况下的颗粒物衰减率损失系数随监测点高度变化情况。结果显示,单侧受限浮力羽流作用处的颗粒物浓度波动较明显;在近壁热源温度≤60℃时,近壁热源上方的颗粒物衰减率损失系数随着高度的增加而减小。提示单侧受限浮力羽流对室内空气颗粒物沉积有一定影响。

Analytical Model for Predicting the Heat Loss Effect on the Pyrolysis of Biomass Particles

This paper presents the combined influence of heat-loss and radiation on the pyrolysis of biomass particles by considering the structure of one-dimensional, laminar and steady state flame propagation in uniformly premixed wood particles. The assumed flame structure consists of a broad preheat-vaporization zone where the rate of gas-phase chemical reaction is small, a thin reaction zone composed of three regions: gas, tar and char combustion where convection and the vaporization rate of the fuel particles are small, and a broad convection zone. The analysis is performed in the asymptotic limit, where the value of the characteristic Zeldovich number is large and the equivalence ratio is larger than unity(i.e.u≥1). The principal attention is made on the determination of a non-linear burning velocity correlation. Consequently, the impacts of radiation, heat loss and particle size as the determining factors on the flame temperature and burning velocity of biomass particles are declared in this research.

燃煤电厂烟气湿度控制对PM_(2.5)采样结果的影响

为研究脱硫后高湿烟气相对湿度的改变对颗粒物采样结果的影响,使用扩散干燥管对烟气进行除湿,并分析不同相对湿度下PM_(2.5)的粒径分布、传输损失和质量浓度变化。结果显示,模拟烟气湿度越高,PM_(2.5)粒数浓度和质量浓度也随之升高。40%相对湿度下,模拟烟气中ρ(PM_(2.5))为22.77 mg/m^(3),粒数浓度约为1.16×10^(6)个/cm^(3),模拟烟气湿度提升至50%、60%和80%时,ρ(PM_(2.5))分别升高1.06,4.35,4.69倍,粒数浓度分别升高1.31,1.70,1.76倍;使用扩散干燥管对模拟高湿烟气除湿,采集到的颗粒物质量浓度有不同程度的下降,最高相对湿度(94.9%)下,ρ(PM_(2.5))为27.17 mg/Nm^(3),湿度81.4%、68.5%、48.7%和30.4%时,质量浓度相比最高湿度时分别降低了14.5%、28.8%、43.0%和45.7%;烟气除湿可降低PM_(2.5)在管路内和切割头内的损失,在94.9%、81.4%和68.5%相对湿度下采集到的ρ(PM_(2.5))分别是对照组的3.02,2.73,2.57倍。高湿烟气除湿降低了颗粒物的含水率,使得PM_(2.5)的质量浓度测量结果随着除湿强度增加而降低,但因除湿降低了颗粒物损失,相比对照组最终采集到的PM_(2.5)质量浓度随着除湿强度增加而显著提升。