Study on characteristics of different types of nozzles for coal-water slurry atomization

Abstract

Three types of nozzles: a low-pressure multistage nozzle, an effervescent nozzle and a newly developed internalmixing air-blast nozzle, for atomization of Coal-Water Slurry (CWS) were investigated. Influence of CWS properties including surface tension and apparent viscosity on atomization was studied. Comparisons among the nozzles were carried out in terms of spray droplet mean diameter and fuel output. Versatility of each nozzle was investigated and atomization mechanism of each nozzle was analyzed as well. The results showed that the newly developed internal-mixing air-blast nozzle has high fuel output and small mean droplet size in the spray, but the multistage nozzle has high versatility for handling of low quality CWS.

Spraying of Composite Liquid Fuels Based on Types of Coal Preparation Waste: Current Problems and Achievements: Review

“…Mixing fuel and gas directly in the injector body results in a more even distribution of droplets in the polydisperse flux [22]. Injector designs that implement preliminary mixing of the liquid and gaseous phases are diverse: they rely on bubbling [18,23], special flow restrictors [18,24], as well as multistage mixing [22]. This inevitably complicates the geometry of the atomizing system, while leading to more intensive pollution of its constituents.…”

“…A typical operation mechanism is illustrated by the structures presented in Figure 1: the fuel and atomizing agent (normally air) are pumped into a mixing chamber, out of which a fine gas-fuel mixture flows. Examples of the respective mixing method are shown in Figure 1 (according to [18,20,24]). The characteristics of the coal-water paste (CWP) atomi tors of two design options were researched in [18].…”

“…The injectors of three designs were used in [24], including an injector with internal mixing (Figure 1c). Experiments with the atomization of several types of coal-water suspensions have been carried out.…”

“…However, in the presence of large particles of the solid component of the fuel composition, there is a high risk of clogging of the internal mixing injector. This risk is due to the energy of the blast air being not sufficient to disintegrate such clogs [24].…”

Effect of gas jet angle on primary breakup and droplet size applying coaxial gas-assisted atomizers

“…In the aforementioned studies, high-velocity annular gas streams with a straight exit channel were typically utilized. Nonetheless, industrial applications typically use a converging exit (straight inner, angled outer wall) or an angled gas exit (inner and outer wall angled) [9][10][11][12][13].…”