A. Ahlstrom Corporation

Bertel K Hakulin

Jorma J Nieminen

Folke Engstrom

Seppo Kalervo Ruottu

Erkki J Kiiskila

Marjo Kuusio

A method and apparatus for recovering black liquor chemicals and heat in a sulphate pulp process. The black liquor is concentrated in an evaporation plant, which includes a pressure heating reactor, after which the black liquor is gasified or combusted in a reactor for producing hot gases. The hot gases formed in the reactor are introduced into gas turbine power plant. The exhaust gases from the gas turbine are introduced into a waste heat boiler, where steam is generated for a steam turbine power plant. Secondary steam is led from the pressure heating reactor as injection steam into the gas turbine, to control inlet temperature.

Method for treating black liquor

A method and apparatus for gasifying or combusting solid, carbonaceous material a circulating fluidized bed reactor. Particles are separated from the product gas at least in two stages so that in the first stage, mainly coarser, so-called circulating particles are separted and returned to the reactor. In the second stage, fine carbonaceous particulates are separated from the gas and are made to agglomerate at a raised temperature. Coarser particles thus received are returned to the reactor through a return duct together with circulating particles. Adhesion of agglomerating particles to the walls of the duct is prevented preferably by leading hot particulates to the center of the duct and circulating particles to the walls of the duct.

Apparatus for gasifying or combusting solid carbonaceous

A method for gasifying or combusting solid, carbonaceous material in a circulating fluidized bed reactor. Particles are separated from the product gas at least in two stages so that in the first stage, mainly coarser, so-called circulating particles are separted and returned to the reactor. In the second stage, fine carbonaceous particlates are separated from the gas and are made to agglomerate at a raised temperature. Coarser particles thus recieved are returned to the reactor through a return duct together with circulating particles. Adhesion of agglomerating particles to the walls of the duct is prevented preferably by leading hot particulates to the center of the duct and circulating particles to the walls of the duct.

Method for gasifying or combusting solid carbonaceous material

In a two-stage combustion method first and second circulating fluidizing bed systems are utilized. The first bed system is operated under reducing (sub-stoichiometric) conditions so as to minimize NO.sub.x formation. Solids in the flue gases are separated and returned to the first bed system, while the flue gases are subjected to afterburning in the second bed system. Oxygen containing gas is supplied to the second bed system to effect afterburning, and additionally sulfur absorbing and/or NO.sub.x formation decreasing agents are supplied to the second system. When burning coal, the first system is operated at a temperature of about 700.degree.-1000.degree. C., while the second system is operated at about 600.degree.-950.degree. C. The flue gases may be cooled, just prior to effecting separation of the solids, in one or both of the bed systems.

Growing community of inventors

Helsinki, Finland

Bertel K Hakulin