Effect of Reactant Mixing on Fine Particle Production in a Tubular Flow Reactor

Abstract

Ammonia and nitric acid were combined in a tubular flow reactor using single- and multiple-jet mixing heads to form ammonium nitrate aerosol. Particle concentrations from 10 to 107/cm3, number-average particle diameters from 0.05 to 0.3 μm, and mass loadings to 10 mg/m3were studied. Experiments and theories indicated that the system behaved like a well-mixed reactor followed by a laminar flow reactor. Above a critical saturation ratio, particle formation and growth took place in the reactant-mixing region; as a result, the aerosol dynamics were controlled by reactant mixing. Below the critical saturation ratio, the aerosol dynamics were not influenced by mixing since particle formation and growth took place mainly in the laminar flow region. Seeding the reactant gas streams narrowed the particle-size distribution and increased aerosol yields. © 1987, American Chemical Society. All rights reserved.