A method and a system for adjusting ph of green liquor dregs

Patent metadata

Field	Value
Publication number	US-2022275578-A1
Application number	US-202017633055-A
Country	US
Kind code	A1
Filing date	Aug 18, 2020
Priority date	Aug 22, 2019
Publication date	Sep 1, 2022
Grant date	—

Abstract

The specification relates to a method and a system for adjusting pH of green liquor dregs. The method comprises contacting a slurry containing green liquor dregs (100, 200, 300, 400, 500) with flue gas (101, 201, 301, 401, 501). The system comprises a recovery boiler (105) configured to burn black liquor to produce smelt, a smelt dissolving tank (107) configured to dissolve the smelt to produce green liquor comprising green liquor dregs, and a green liquor clarifier/filter (103) and/or a dregs filter (104) configured to separate a slurry containing green liquor dregs (100, 200, 300, 400, 500) from the green liquor. The system further comprises a vessel (102, 202, 302, 402) configured to receive a slurry containing green liquor dregs (100, 200, 300, 400, 500) and a gas inlet (210, 310, 410, 510) configured to convey flue gas (101, 201, 301, 401, 501) to be contacted with the slurry containing green liquor dregs (100, 200, 300, 400, 500).

First claim

1 - 14 . (canceled)

15 . A method for adjusting pH of green liquor dregs, the method comprising:
contacting a slurry containing green liquor dregs ( 100 , 200 , 300 , 400 , 500 ) with flue gas ( 101 , 201 , 301 , 401 , 501 ), wherein:
the slurry containing green liquor dregs ( 100 , 200 , 300 , 400 , 500 ) originates from a green liquor clarifier/filter ( 103 ) and/or a dregs filter ( 104 ) configured to separate the slurry containing green liquor dregs ( 100 , 200 , 300 , 400 , 500 ) from green liquor,
a dry solids content of the slurry containing green liquor dregs ( 100 , 200 , 300 , 400 , 500 ) is from 1 to 40 wt. %,
the flue gas ( 101 , 201 , 301 , 401 , 501 ) contains carbon dioxide, and
a pH of the green liquor dregs after contacting with the flue gas ( 101 , 201 , 301 , 401 , 501 ) is between 7-9.

16 . The method according to claim 15 , wherein a temperature of the slurry containing green liquor dregs is at most 150° C. and a temperature of the flue gas is at most 400° C.

17 . The method according to claim 16 , wherein a dry solids content of the slurry containing green liquor dregs is from 1 to 20 wt. %.

18 . The method according to claim 15 , wherein a dry solids content of the slurry containing green liquor dregs is from 1 to 20 wt. %.

19 . The method according to claim 14 , wherein the flue gas ( 101 , 201 , 301 , 401 , 501 ) originates from a recovery boiler ( 105 ).

20 . The method according to claim 15 , wherein the flue gas ( 101 , 201 , 301 , 401 , 501 ) originates from burning of at least a renewable fuel.

21 . The method according to claim 15 , wherein the method comprises bubbling the flue gas ( 101 , 201 , 301 , 401 , 501 ) into the slurry containing green liquor dregs ( 100 , 200 , 300 , 400 , 500 ).

22 . The method according to claim 15 , wherein the method further comprises:
directing the slurry containing green liquor dregs ( 100 , 200 , 300 , 400 , 500 ) and the flue gas ( 101 , 201 , 301 , 401 , 501 ) to an injector arrangement ( 411 ); and mixing the slurry containing green liquor dregs ( 100 , 200 , 300 , 400 , 500 ) and the flue gas ( 101 , 201 , 301 , 401 , 501 ) in the injector arrangement ( 411 ).

23 . The method according to claim 15 , wherein the method comprises spraying the slurry containing green liquor dregs ( 300 ) in a counter-current manner to the flue gas ( 301 ).

24 . The method according to claim 16 , wherein the method comprises spraying the slurry containing green liquor dregs ( 300 ) in a counter-current manner to the flue gas ( 301 ).

25 . The method according to claim 18 , wherein the method comprises spraying the slurry containing green liquor dregs ( 300 ) in a counter-current manner to the flue gas ( 301 ).

26 . The method according to claim 19 , wherein the method comprises spraying the slurry containing green liquor dregs ( 300 ) in a counter-current manner to the flue gas ( 301 ).

27 . The method according to claim 20 , wherein the method comprises spraying the slurry containing green liquor dregs ( 300 ) in a counter-current manner to the flue gas ( 301 ).

Assignees

• Valmet Technologies Oy

Inventors

• Vettenranta Aino

Classifications

• D21C11/0064 Primary

  Aspects concerning the production and the treatment of green and white liquors, e.g. causticizing green liquor · CPC title

• D21C11/0007 Primary

  Recovery of by-products, i.e. compounds other than those necessary for pulping, for multiple uses or not otherwise provided for (volatile compounds obtained by decomposition of spent liquors in order to regenerate them D21C11/125; compounds obtained by fractionating the liquors in order to regenerate them D21C11/0042) · CPC title

• D21C11/0085

  Introduction of auxiliary substances into the regenerating system in order to improve the performance of certain steps of the latter, the presence of these substances being confined to the regeneration cycle (introduction of compounds in order to make up for the losses of pulping agents D21C11/0035; conventional causticizing of green liquors D21C11/0064; fractionating of spent liquors D21C11/0042) · CPC title

• D21C11/0071 Primary

  Treatment of green or white liquors with gases, e.g. with carbon dioxide for carbonation; Expulsion of gaseous compounds, e.g. hydrogen sulfide, from these liquors by this treatment (stripping); Optional separation of solid compounds formed in the liquors by this treatment (oxidation of liquors (black, green or white) D21C11/0057; treatment of pulp gases D21C11/06) · CPC title

• D21C11/12

  Combustion of pulp liquors · CPC title