EXPERIMENTAL RESEARCH OF MIXING NATURAL GAS IMPINGING JETS AND AIR DURING COMBUSTION AT A VERTICAL REFRACTORY SURFACE

Abstract

In the work determined the conditions for the start of chemical reactions of natural gas and air mixture at combustion on a refractory surface, when a single submerged turbulent impinging jet is fed from a natural gas collector at the angle α to the vertical refractory surface, at the relative distance L/d0 along the geometric axis of the jet. It is determined that combustion starts under the condition when the excess air coefficient in the mixture reaches about λ = 0.93, at which the laminar flame propagation velocity S°L, m/s, for a premixed mixture of methane and air is maximum. The dependence of the height of the flame Lf, m, on the relative dimensionless step of the location of the nozzles s/d0 in the row was obtained during studying the groups of gas nozzles with the supply of natural gas for combustion through them range diameters 1–3.5 mm (which are used at precent time in the construction of slot bottom burners). It was determined that the flame height of slot bottom burner during its operation on natural gas (tested for the pressure of natural gas in the collector from 2 kPa to 18 kPa, respectively, natural gas outflow velocity, WNG from about 60 m/s to 185 m/s) depends slightly on gas pressure, the relative distance L/d0 that the aerated jet of natural gas travels to the refractory surface in the range of 15 ≤ L/d0 ≤ 30 and the Reynolds number, and strongly depends from on the dimensionless step of the nozzles in the row — s/d0. It has been experimentally proven that by adjusting the dimensionless step of the nozzles (holes) s/d0 in the row of the slot bottom burner, it is possible to adjust the height of the flame and thus obtain the flame of the appropriate height for different heights of fireboxes and boilers powers. Bibl. 29, Fig. 3, Tab. 3.