Liquid Phase Mass Transfer in Spray ContactorsEPA Grant Number: U915396
Title: Liquid Phase Mass Transfer in Spray Contactors
Investigators: Yeh, Norman K.
Institution: The University of Texas at Austin
EPA Project Officer: Carleton, James N
Project Period: September 1, 1998 through August 1, 2001
Project Amount: $77,276
RFA: STAR Graduate Fellowships (1998) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Engineering and Environmental Chemistry , Fellowship - Chemical Engineering
The objectives of this research project are to: (1) measure the liquid phase mass transfer in sprays for gas-liquid contacting; and (2) investigate how the mass transfer rate varies with the distance from the nozzle and the pressure drop through the nozzle.
Mass transfer coefficients in drops are strong functions of the drop size and formation; therefore, the drop sizes and dynamic behavior of drops in spray scrubbing will be reproduced with a commercial-scale nozzle. Working with a commercial-scale nozzle provides several challenges, including high liquid flow rates and drop velocities. Thus, an experimental column was designed to sample a small fraction of the total spray. The column consists of two sections separated by a wall with a narrow slot. Most of the spray is contained in the first section, but a small portion of the spray passes through the slot into the second section of the column. In the second section of the column, more mass transfer may occur, and the spray may be sampled. The desorption of carbon dioxide in an air-water system will be studied to determine the liquid phase mass transfer, because the low solubility of CO2 in water favors liquid-phase control of the mass transfer. CO2 gas is sparged into the feed piping upstream of the nozzle so that the gas may be dissolved before reaching the nozzle. Liquid samples will be collected and analyzed to obtain the CO2 concentration as a function of the distance from the nozzle. The drop size distribution of the spray will be measured using high-speed photography. Drop velocities and contact times will be calculated from drag correlations or will be measured using a method such as high-speed double flash photography. Using the contact time and drop size distribution, mass transfer coefficients may be calculated from the observed CO2 concentrations in the spray. This procedure should allow the effects of nozzle selection and operating pressure on the mass transfer coefficient to be quantified.