Collisions of Two-Phase Liquid Droplets in a Heated Gas Medium.

The paper presents the experimental research findings for the integral characteristics of processes developing when two-phase liquid droplets collide in a heated gas medium. The experiments were conducted in a closed heat exchange chamber space filled with air. The gas medium was heated to 400-500 °C by an induction system. In the experiments, the size of initial droplets, their velocities and impact angles were varied in the ranges typical of industrial applications. The main varied parameter was the percentage of vapor (volume of bubbles) in the droplet (up to 90% of the liquid volume). The droplet collision regimes (coalescence, bounce, breakup, disruption), size and number of secondary fragments, as well as the relative volume fraction of vapor bubbles in them were recorded. Differences in the collision regimes and in the distribution of secondary fragments by size were identified. The areas of liquid surface before and after the initial droplet breakup were determined. Conditions were outlined in which vapor bubbles had a significant and, on the contrary, fairly weak effect on the interaction regimes of two-phase droplets.

Effective incineration of fuel-waste slurries from several related industries.

This study is based on the analysis of a set of industrial sectors (coal processing, wood processing, transport, oil, and water treatment) in order to identify the amount and type of combustible waste suitable for incineration. The main ignition and combustion parameters of these wastes have been experimentally obtained from their direct individual incineration in the original form and as part of a slurry based on wastewater. It has been established that a set of parameters allow waste-derived fuel mixtures to compete with coal dust and fuel oil with an environmental advantage. In particular, the concentration of sulfur and nitrogen oxides in the combustion products of all the tested slurries is 1.5-3 times as low as that of coal dust. Most of the wastes in question do not provide such advantages when burnt individually. We have assessed the fire safety of fuel mixtures and analyzed the prospects of mass waste incineration technologies. The calculations show that about 14-20% of coal and oil can be saved annually by extensively involving industrial waste in the energy sector. The experimental results obtained are the basis for the development of useful technologies for the safe and efficient combustion of waste from different industries.