Detonation combustion of lignite with titanium dioxide and water additives in air

The influence of mineral additives (6.2–70%) and water (15–54%) to lignite on the possibility of its burning in an air flow in a continuous detonation regime in a radial vortex combustor 500 mm in diameter is studied. A syngas with a composition CO + 3H$_2$ is used for transporting the coal mixture and for promoting the chemical reaction. It is shown that regimes of continuous spin detonation, conventional combustion, and pulsed combustion may occur depending on the amounts of the mineral (TiO$_2$) added to coal, water, and syngas. The boundaries between the domains of existence of detonation and combustion are determined in the coordinates of the ratio of the syngas flow rate to the rate of consumption of the combustible portion of coal and the mineral component of coal and water. It is seen that the continuous spin detonation regime persists if the mineral additive fraction in the lignite mixture is up to 65% and the water fraction is smaller than 30%. It is also demonstrated that the syngas flow rate should be increased with increasing mineral additive fraction and increasing coal humidity in order to ensure burning of the combustible component of syngas.