X. Ma1, Anshuman Lall2, Dale Huang2, and Michael Zachariah3. (1) University of Maryland-College Park, College Park, MD 20742, (2) Department of Mechanical Engineering, University of Maryland-College Park, College Park, MD 20742, (3) University of Maryland and NIST, 2125 Glenn L Martin Hall, College Park, MD 20742
A new relatively large-scale laboratory reactor (up to ~100 g/hr) for carbon black synthesis via improved soot surface growth is developed. The reactor consists of a diffusion flame on which the heated fuel/liquid precursor is sprayed in gas/droplet form with nitrogen as carrier gas. The sprayed fuel gets partially pyrolyzed to carbonaceous soot particles and other gaseous byproducts. The resulting soot aerosol is maintained at a high temperature for a certain time to allow soot surface growth onto previously formed seed soot particles. However, the overall soot yield is a complex interplay of competing soot surface growth [Yozgatligil, A. and Zachariah, M. R. (2008) Measurement of soot surface growth kinetics. Combust. Sci. and Tech., 180: 941–949] and post-oxidation kinetics. Our goal is to optimize soot yield by improving the soot surface growth. In our preliminary measurements, it is found that a higher reactor temperature leads to lower yield due to higher soot post-oxidation rate. The results are supported by the increase in total CO and CO2 concentrations.
The soot yield measurements are made by using a novel online aerosol method of measuring soot yield in the gas phase. The online method enabled us to measure soot yield without knowing the total product flow rate for a number of process parameters and operating conditions such as the overall and burner equivalence ratio, and the time-temperature history. Our preliminary measurements indicate that the soot yield increases with the overall equivalence ratio at a given burner equivalence ratio. The CO and CO2 emissions from the reactor are monitored and suggestions are made to reduce emissions of the green-house gases.