On the study of coal-water fuel flow structure during its pneumatic-mechanical atomization

The paper describes the experimental studies of the structure of coal-water fuel (CWF) flow during its pneumatic spraying in the aerodynamic simulator of the energy boiler furnace. It analyses the 50 % coal and 50 % water CWF spraying mechanism. Parameters: coal particle size was 50 microns or less; temperature was 313 K, 353 K; pressure of CWF was 3 MPa; and pressure of air was 2 MPa. The visualization of CWF torch structure and the assessment of the flow quality were made in the plane perpendicular to the axis of the spray cone in three positions. Geometrical parameters and velocities of CWF droplets during spraying were determined. The change of the We criterion was analyzed depending on CWF drops velocity and their size. The characteristic zones of CWF spray cone, which are generated during spraying, were established. The ranges of diameters and velocities of CWF droplets corresponding to the core of the flow, the middle and outer zones of the spray cone were determined. The We values were calculated for the corresponding CWF droplets sizes and velocities. The conditions typical for some stages of droplets crushing of sprayed CWF were described. The research outcomes can be used for the mathematical and physical simulations of CWF spraying in the furnaces of power boilers to estimate the forecast aerodynamic characteristics of the designed and existing units.