The impact of major gaseous and particulate pollutants emitted by the wildfire of October 2003 on ambient air quality and health of San Diego residents before, during, and after the fire are analyzed using data available from the San Diego County Air Pollution Control District and California Air Resources Board. It was found that fine particulate matter (PM) levels exceeded the federal daily 24-hr average standard during the fire. There was a slight increase in some of the gaseous pollutants, such as carbon monoxide, which exceeded federal standards. Ozone (O3) precursors, such as total hydrocarbons and methane gases, experienced elevated concentration during the fire. Fortunately, the absence of sunlight because of the cloud of thick smoke that covered most of the county during the fire appears to have prevented the photochemical conversion of the precursor gases to harmful concentrations of O3. Statistical analysis of the compiled medical surveillance data has been used to establish correlations between pollutant levels in the region and the resultant health problems experienced by the county citizens. The study shows that the increased PM concentration above the federal standard resulted in a significant increase in hospital emergency room visits for asthma, respiratory problems, eye irritation, and smoke inhalation. On the basis of the findings, it is recommended that hospitals and emergency medical facilities engage in pre-event planning that would ensure a rapid response to an impact on the healthcare system as a result of a large wildfire and appropriate agencies engage in the use of all available meteorological forecasting resources, including real-time satellite imaging assets, to accurately forecast air quality and assist firefighting efforts.

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The performance of the Brink and Contant industrial-size Venturi scrubber has been successfully simulated by means of a two-dimensional computer model. The two-phase, two-component, annular flow occurring in the unit was predicted using a Particle-In-Cell (PIC) numerical technique. Consideration of four different dust diameters, ranging from 0.5 to 10 µm, allowed evaluation of the Venturi grade efficiency curve. Liquid jet penetration and drop size distributions, incorporated as important parameters, were linked to significant liquid maldistribution in the Venturi throat. This study confirmed the observation that the drops are actually classified by inertial effects which enable bigger drops to penetrate further into the central core of the air stream and the smaller drops to stay closer to the duct walls. As a result, the smaller drops were not observed in the region occupied by the larger drops. This liquid maldistribution persisted throughout the scrubber and resulted in predictions of particulate collection efficiency that were lower than would be expected with the usual assumption of uniformly distributed drops of one size using one-dimensional models. Because this two-dimensional model can incorporate different liquid injection modes and drop size distributions, it provides considerable versatility for the simulation of cleaning processes in Venturi scrubbers.

An annular flow pressure drop model has been developed and compared with experimental data obtained on a pilot-plant-size Pease-Anthony-type venturi scrubber. Droplet and film accelerations as well as wall friction, based on the two-phase Lockhart-Martinelli correlation, are considered. Excellent agreement with experimental data is demonstrated for a wide range of throat gas velocities, liquid to gas ratios, and film flow rates for a single scrubber geometry. Venturi scrubbers have been recognized widely for their high particulate matter collection efficiencies. Fine-particle collection generally requires elevated pressure drops. The primary objective of this study was to develop a realistic mathematical model for prediction of pressure drop in a PeaseAnthony venturi scrubber.Flow losses are predicted by accounting for frictional effects and acceleration of liquid drops and the liquid films flowing on the walls. Recovery in the diffuser is also considered. Model validation involved measurement of pressure gradients, film flow rates, liquid to gas ratios, and throat gas velocities for a pilot-plant-scale venturi. A comparison is made among three widely used correlations using experimental data taken from the pilot-plant-scale venturi scrubber. CONCLUSIONS AND SIGNIFICANCEAn annular flow model is developed for accurate prediction of pressure drops in Pease-Anthony venturi scrubbers. This model-which considers the primary design parameters of liquid to gas ratio, throat gas velocity, venturi geometry, and liquid film flow rate-accurately predicted the measured pressure gradients and overall energy losses.The Hesketh (1974) correlation underestimated pressure drops at all liquid to gas ratios and throat gas velocities tested. The Calvert modified model (Yung et al., 1977a) predicted overall pressure drops lower than those experimentally measured for liquid to gas ratios below 8.0 X lod4 m3 liquid/m3 air, and greater magnitudes for liquid to gas ratios exceeding 1.3 xThe region of good agreement was achieved in spite of the neglect of wall friction, converging section losses, and diffuser pressure recovery when these effects compensated each other.Boll 's model (1973) consistently overpredicted the experimental pressure drops. The deviation increased with increasing liquid to gas ratios. Since film flow was not considered, the droplet acceleration component was always overestimated. The frictional losses, which were predicted using a homogeneous model (Wallis, 1969), were overestimated.

The maximum centreline penetrations, l**, of cross‐current liquid jets in a Venturi scrubber were measured for orifice diameters, d, of 1.397, 2.108, 2.565 and 3.860 mm. The data are correlated by for the range of conditions, 36 ≤ gas throat velocity Vg ≤ 125 m/s; 1.2 ≤ liquid injection velocity Vj ≤ 18 m/s; 0.06 ≤ liquid to gas ratio