A system (10) for treating spent pulping liquor (14) comprising lignin to provide green liquor (47) is disclosed. The system (10) comprises an evaporator (22), a recovery boiler (34), at least one filter (58, 74), and a green liquor plant (46). The evaporator (22) concentrates a first stream (18) of the spent pulping liquor (14) to provide a concentrated pulping liquor (30). The recovery boiler (34) incinerates the concentrated pulping liquor (30) to provide a smelt (42). The at least one filter (58, 74) filters a second stream (54) of the spent pulping liquor (14) to remove lignin therefrom to provide a permeate (66, 82). The green liquor plant (46) is for dissolving the smelt (42) from the recovery boiler (34) in the permeate (66, 82) from the at least one filter (58, 74) to provide green liquor (47). Also disclosed is a method for treating spent pulping liquor (14) to provide green liquor (47).

The invention herein disclosed and claimed is a process for refining fiber from lignocellulosic biomass. The process provides refined fiber and agriculturally amenable co-products, with a virtually waste-free systems design.

Various techniques are described for enhanced combustion of hot water extraction (HWE) derived liquor. For example, the HWE derived liquor can be pre-treated prior to introduction into a combustion chamber. The pre-treatment can include subjecting HWE derived liquor to filtration to remove suspended solids, evaporation to produce a first stage concentrated HWE liquor; additional concentration to produce a second stage concentrated HWE liquor; additional filtration to remove additional suspended solids; and pre-heating to produce a preheated HWE liquor. The preheated HWE liquor can be atomized and combined with pre-heated combustion air supplied into a combustion chamber to effect combustion of the HWE derived liquor.

Various techniques are described for enhanced combustion of hot water extraction (HWE) derived liquor. For example, the HWE derived liquor can be pre-treated prior to introduction into a combustion chamber. The pre-treatment can include subjecting HWE derived liquor to filtration to remove suspended solids, evaporation to produce a first stage concentrated HWE liquor; additional concentration to produce a second stage concentrated HWE liquor; additional filtration to remove additional suspended solids; and pre-heating to produce a preheated HWE liquor. The preheated HWE liquor can be atomized and combined with pre-heated combustion air supplied into a combustion chamber to effect combustion of the HWE derived liquor.

There is described a process for the recovering of inorganic chemicals of pulp and paper making processes (IC) and the production of biochemicals from black liquor (BL) using microwaves (MW) comprising: (a) filtration of BL to produce filtered BL, in a media, (b) drying of said filtered BL with MW in said media to produce dried BL, (c) pyrolysis of said dried BL with MW in said media to produce bio-oil, biogas, and solid residue, (d) recovering of said bio-oil, and (e) recovering of IC and biocarbon from said solid residue. The disclosed process does not require chemical additives compared to processes rely on precipitation of lignin to recover said IC. The disclosed process supports efficient, direct, and long-lasting reductions in greenhouse gas emissions and local air pollutants resulting from the current processes rely on burning BL in recovery boilers to recover said IC.

There is described a process for the recovering of inorganic chemicals of pulp and paper making processes (IC) and the production of biochemicals from black liquor (BL) using microwaves (MW) comprising: (a) filtration of BL to produce filtered BL, in a media, (b) drying of said filtered BL with MW in said media to produce dried BL, (c) pyrolysis of said dried BL with MW in said media to produce bio-oil, biogas, and solid residue, (d) recovering of said bio-oil, and (e) recovering of IC and biocarbon from said solid residue. The disclosed process does not require chemical additives compared to processes rely on precipitation of lignin to recover said IC. The disclosed process supports efficient, direct, and long-lasting reductions in greenhouse gas emissions and local air pollutants resulting from the current processes rely on burning BL in recovery boilers to recover said IC.

An anaerobic digestion system may include a material grinding/pulping portion, a hydrolysis portion arranged downstream of the grinding portion, a multiple chamber anaerobic reactor arranged downstream from the hydrolysis portion and including a gas collection and reintroduction system, a collection system for collecting digestate and gas from the anaerobic reactor.

The present application discloses an alternative method for selective removal of K.sup.+ and Cl.sup. from recovery boiler electrostatic precipitator ashes in a kraft-pulp process through the use of pure or impure CO.sub.2, complemented or not with a mineral acid, for instance Sulfuric Acid/Spent Acid.

The present application discloses an alternative method for selective removal of K.sup.+ and Cl.sup. from recovery boiler electrostatic precipitator ashes in a kraft-pulp process through the use of pure or impure CO.sub.2, complemented or not with a mineral acid, for instance Sulfuric Acid/Spent Acid.

A chemical recovery boiler (100), including a furnace (1), comprising a front wall (2), a back wall (3), and the back wall (3) comprising a nose arch (4). The boiler further comprises at least one superheater (5) arranged in upper part of the furnace (1), and a screen pipe system (6), comprising an obliquely arranged screen pipe section (7) positioned before/under the at least one superheater (5) in the furnace (1). The obliquely arranged screen pipe section (7) comprises screen pipes (8) ascending (i) either from the front wall (2) to the back wall (3), and arranged to turn back in a turn (13) from the back wall (3) and extend obliquely upwards from the back wall (3), or (ii) from the back wall (3) to the front wall (2), and arranged to turn back in a turn (13) from the front wall (2) and extend obliquely upwards from the front wall (2). The screen pipe system (6) further comprises a vertically arranged screen pipe section (9) extending from the obliquely arranged screen pipe section (7). The screen pipes (8) of the vertically arranged screen pipe section (9) are arranged to extend parallel with the at least one superheater (5) in upper part of the furnace (1).