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: 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.

Abstract: In a combustion air supply system, particularly a secondary air supply system for a recovery furnace, the secondary air inlet ports are divided into two arrays in such a manner that the combustion air coming in through the inlet ports of the first array is directed in part to contact and in part to by-pass a central region in the outer surface of a carbonization layer. The combustion air coming in through the inlet ports of the second array is directed to by-pass the combustion air coming in through the inlet ports of the first array thereabove. The first and second arrays are located on the opposite walls of the combustion chamber, preferably on the front and rear walls. The recovery furnace further comprises a primary air supply zone for blowing combustion air onto the sides of the carbonization layer and a tertiary air supply zone above a waste liquor inlet.

Abstract: The invention relates to a method of regulating, for the purpose of burning soda-ash in a recovery boiler furnace, the feeding-in or combustion conditions of concentrated spent liquors of varying chemical and physical properties by measuring some physical property of a liquor fed into the recovery boiler furnace and by regulating the feeding-in and combustion conditions directly on the basis of the thus measured physical properties. According to the invention, the maximum swelling, upon heating, of a dry-matter particle of the liquor fed into the recovery boiler furnace is measured. On the basis of this measurement the temperature, pH value, or injection pressure of the liquor fed into the furnace, or the height of the injection point or the direction of injection, or the feeding of air into the furnace is adjusted directly on the basis of the maximum swelling measurement.