Research of the spraying and ignition characteristics of coal-water fuels with isopropyl alcohol addition

The article presents complex experimental studies of the effect isopropyl alcohol in the composition of coal-water fuel (CWF) has on the jet characteristics and the ignition delay time of the slurry droplets. CWF with minor additions of isopropyl alcohol (from 3 to 8%) was sprayed using a pneumatic nozzle on a specialized stand. Investigations of the ignition delay time were performed in a temperature-controlled furnace in a wide range of oxidant temperatures (from 600 to 1000 °C). The rheological characteristics of the studied fuels, i.e. viscosity, density and surface tension were measured. It was determined that replacing water in the CWF composition with isopropyl alcohol contributes to increased viscosity of the resulting fuel. However, this parameter remains within acceptable limits even at the maximum studied concentration of the third component. It was found that the introduction of isopropyl alcohol into the composition of coal-water fuel based on lean coal leads to an increase in the jet spraying angle up to 11%. This contributes to an even distribution of fuel droplets inside the combustion chamber. As a result, the number of large droplets (more than 600 microns) increases only slightly - less than 2% at an alcohol concentration of 8% by mass. The ignition delay time at such an alcohol concentration decreases by half compared to the two-component CWF at a temperature of 1000 °C.