METHOD FOR EXTRACTING AMMONIUM SALT AND METHANOL FROM A LIQUID OBTAINED FROM FOUL CONDENSATES IN A CELLULOSE PULP MILL

• US 20100316553A1
• Filed: 11/26/2008
• Published: 12/16/2010
• Est. Priority Date: 11/26/2007
• Status: Active Grant

• Current Assignee: Metso Power AB, Processum Biorefinery Initiative AB
• Original Assignee: Metso Power AB, Processum Biorefinery Initiative AB
• Inventors: Norberg, Anders Johan, Brucher, Jorg
• Granted Patent: US 8,440,159 B2
• Time in Patent Office: Days
• US Class Current: 423/388
• CPC Class Codes: D21C 11/00 Regeneration of pulp liquors or effluent waste waters
• CPC Class Codes: D21C 11/06 Treatment of pulp gases; Recovery of the heat content of the gases; Treatment of gases arising from various sources in pulp and paper mills; Regeneration of gaseous SO2, e.g. arising from liquors containing sulfur compounds
• CPC Class Codes: D21C 11/08 Deodorisation ; Elimination of malodorous compounds, e.g. sulfur compounds such as hydrogen sulfide or mercaptans, from gas streams oxidation of liquors D21C11/0057; post-combustion of gases D21C11/127
• CPC Class Codes: D21C 11/10 Concentrating spent liquor by evaporation evaporators B01D

Abstract

Desirable chemicals are recovered from a raw material that is formed in substantial amounts during the production of cellulose pulp from renewable lingo-cellulose material. An ammonia/ammonium-containing methanol/water mixture is acidified with an acid that has the ability of forming ammonium salt with the ammonium. The mixture is circulated and passed through an apparatus that has an indirect heat exchanger combined with an storage volume fitted with a gas collection device.

Claims

1. A method for extracting a highly purified ammonium salt and highly purified methanol from a secondary condensate containing an ammonia/ammonium-containing methanol/water mixture, comprising:

obtaining the methanol/water mixture from stripping a contaminated primary condensate derived from a digestion house during a delignification of lignocellulose material to cellulose pulp with an alkaline cooking liquor, and/or from evaporation of cooking waste liquor,

acidifying the secondary condensate with an acid having an ability to form an ammonium salt with the ammonium contained in the secondary condensate, subjecting the mixture of the secondary condensate and acid to heat,

expelling methanol and volatile sulphur-containing substances in gas form transferring the methanol and volatile sulphur-containing substances to a condenser,

condensing the methanol while the volatile sulphur-containing substances remain in gas form, separately removing a liquid phase and a gas phase from the condenser,

adding the acid to the mixture and circulating the mixture,

while circulating the mixture, subjecting the mixture to heating to a temperature above a boiling point of the methanol but below a boiling point of both the added acid and water, the temperature being within a range of 70-105°

C.,

a re-circulation flow of the circulating mixture being at least 2-15 fold that of an inflow of the secondary condensate,

passing the circulating mixture through an apparatus having an indirect heat exchanger combined with a storage volume fitted with a gas collection device,

a net inflow of water via the secondary condensate and the addition of acid maintaining a concentration of ammonium salt at 1-20% below a level at which ammonium salt is precipitated,

the re-circulation of the mixture optimizing the step of expelling the methanol and the volatile sulphur-containing substances from the mixture, withdrawing 5-50%, of the circulating mixture from the re-circulation flow, increasing a proportion of water in the mixture by at least 2-5 fold compared to a proportion of water in the incoming secondary condensate, for collection in a container,

stirring and/or circulating the collected mixture with a high water content to expel at least 80% of a remaining methanol and at least 95% of remaining volatile sulphur-containing substances

adding an oxidizing agent to a recovered liquid methanol, and

converting remaining liquid soluble malodorous sulphur-containing substances to mainly odourless substances.

2. A method according to claim 1, wherein the secondary condensate is derived from a contaminated primary condensate that has been produced during a production of sulphate pulp.

3. A method according to claim 1 wherein the acidification being performed with the acid is of such a strength and in such an amount that a pH value of a water phase in the mixture is within a range of 2-6.5.

4. A method according to claim 3, wherein the acidification is performed with sulphuric acid resulting in a formation of ammonium sulphate.

5. A method according to claim 1, wherein the gases that are removed from the condenser are transferred to a destruction facility.

6. A method according to claim 1 wherein gases of the methanol and volatile sulphur contain substances that are expelled from the ammonium salt contain a liquid collected in a container and either directly transferred to a destruction facility, or after being mixed with the gases, is removed from the condenser.

7. A method according to claim 1, wherein the oxidizing agent is a peroxide.

8. A method according to claim 7, wherein the peroxide is hydrogen peroxide.

9. A method according to claim 1 wherein the methanol, after an oxidation treatment is passed through a decanter to remove any remaining turpentine, before transferring the methanol to a storage tank.

10. A method according to claim 7 wherein a chemical that destroys any remaining peroxide in the methanol is added to the oxidation treated methanol.

11. A method according to claim 10, wherein the chemical is an iron salt.