Abstract: The invention relates to a system for controlling the flow field in a soda recovery boiler, said soda recovery boiler comprising at least a furnace (1), primary air ports (4) in the lower part of the furnace, so-called secondary combustion air ports (5) disposed above these, black liquor spray nozzles (6) placed similiarly above these and combustion air ports (5b) disposed above the black liquor spray nozzles (6). According to the invention, the soda recovery boiler is provided with substantially thin jets (7, 7a, 7b) supplying energy into the flow field and having a jet pressure in the nozzle equal to at least twice the jet pressure in the combustion air ports (5, 5b).

Abstract: This invention is directed to an arrangement and a device for distribution of oxygen-containing gas (air) in a furnace, into which fuel is supplied as solid or fluid particles (1). The fuel consists of e.g. spent liquor from the pulp industry. Said liquor burns partly as char (2) on the floor (3), and partly as suspended particles and as volatiles. Horizontal rows of gas jets (4) activate the char burning on the floor. Vertically extended configuration of gas jets (5) higher up induces strong horizontal gas circulation but reduces vertical flow extremes. The improved horizontal mixing increases burning stability, capacity and energy efficiency, but reduces emission of SO.sub.x, NO.sub.x and TRS. Lowered vertical recirculation permits better concentration of burning in the lower furnace and less carry-over of fuel particles.