10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
The Effect of Potassium Chloride Addition on the Characteristics of Nascent Soot during Ethylene Pyrolysis
Mengda Wang, JUNYU MEI, Quanxi Tang, Xiaoqing You, Tsinghua University
Abstract Number: 681 Working Group: Carbonaceous Aerosol
Abstract Soot as incomplete combustion products has been studied extensively due to its detrimental effect on the environment and human health. For combustion of solid fuel, such as coals and biomass, abundant alkaline and alkaline earth metals would have an interaction with the formation of soot particles. Besides, inorganic substances containing potassium were widely used as additives to improve the quality of carbon black generated from the industrial production process.
In this work, the effect of KCl addition on the characteristics of soot particles formed during the pyrolysis of ethylene/water/nitrogen flow in a flow reactor has been investigated. Particle size distribution functions (PSDFs) of soot particles formed in the flow reactor at different residence time were measured by using micro-orifice probe sampling in tandem with scan mobility particle sizer (SMPS). Meanwhile, a differential mobility analyzer (DMA) applied with a fixed voltage in tandem with SMPS was used to explore the charge characteristics of soot particles. In addition, the morphology of soot particles sampled from the probe was examined using transmission electron microscopy (TEM). From the PSDFs, it was observed that the addition of KCl did not affect much the nucleation of soot particles, but inhibited the growth of soot particles. Besides, the number of particles with double positive charges decreases with the addition of KCl, which indicates the KCl addition neutralized the multi-charged particles. Consequently, the coagulation rate between soot particles was reduced, which led to smaller particles and slower growth by coagulation. Compared to the results of the reference mixture without KCl addition, in the KCl-added mixtures, both the TEM images and the mass-mobility exponent show that soot particles are generally more compact, and the primary particles of soot aggregates have a narrower size distribution and a smaller median diameter.