Drop size and distribution in an annular two-phase flow occurring in a venturi scrubber were measured using a phase Doppler particle analyzer (PDPA) as a function of operating conditions such as gas velocity and liquid-to-gas ratio. At low throat-gas velocities, the maximum measured drop diameter and Sauter mean diameter increased when the liquid-to-gas ratio increased. However, at a fixed liquid-to-gas ratio, the maximum measured drop diameter and Sauter mean diameter decreased with the increase in throat-gas velocity. The experimental data tested with two theoretical distributions, namely, the upper-limit distribution function and the root-normal distribution function in terms of the shape of the drop-size distribution and the frequency values, produced a better agreement with the former than with the latter. It was observed that, in a highly dispersed drop-size distribution produced at a low throat-gas velocity of 45 m/s, a single average drop size is inadequate to describe the entire drop-size distribution, whereas at a high throat-gas velocity, 60 m/s, a single average drop size was found sufficient to describe the entire drop-size distribution formed.
Cyclone dedusters are used in diverse contexts due to their many advantages over other primary collectors. The post cyclone (PoC) is a new secondary collector situated at the top of a conventional reverse flow cyclone, which utilizes the residual swirl available at the gas outlet (vortex finder) of the cyclone to capture a certain fraction of the escaped dust. In this paper, one design of PoC is tested where the particles are collected in a bleed flow drawn from the PoC. Subsequent to the particle separation, the lean bleed flow is recycled back to the inlet of the cyclone. The experiments conducted at different bleed flow rates and inlet velocity indicate an increase in overall efficiency of cyclone by 6% in average, and reduction in emission from the vortex finder by 5-9%.
Abstract The objective of this study was to investigate the effects of combined low-pressure ultraviolet (UV)irradiation and chlorination on the formation of disinfection by-products (DBPs) from different dissolved organic matter (DOM) as DBP precursors. Commercially available humic acid (HA), extracellular organic matter (EOM) from green algae, cyanobacteria, and diatom, namely Scenedesmus quadricauda (SQ), Merismopedia sp. (Msp), and Phaedactylum tricornutum (PT), were used as the sources of DOM. The DBP formation increased with increasing total residual chlorine; EOM from PT presented the highest formation potential followed by HA, Msp, and SQ. The low dosage of 40 mJ/cm2 UV irradiation is insignificant to change the DBP formation from HA and SQ; however, it decreased the DBP formation from bromide-containing EOM of PT and promoted the DBP formation from EOM of Msp at various total residual chlorines. The DBP formation of each DOM correlated well with total residual chlorine. The maximum DBP formation potential (DBPFP) reduction of 42.25 and 13.75% for haloacetic acid formation potential (HAAFP) and trihalomethane formation potential (THMFP) was obtained at the UV irradiation dosage of 300 mJ/cm2 for EOM of PT. However, for the EOM derived from Msp, a maximum increase of 58.1 and 51.1% for HAAFP and THMFP was observed after UV-chlorination.
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