Apparatus for producing ammonia-base pulping liquor from spent liquor

Claim 2

APPARATUS COMPRISING: A FLUIDIZED BED REACTOR HAVING A BED OF MAGNESIA PARTICLES; AN EXHAUST GAS CONDUIT FROM THE FREEBOARD SPACE OF THE REACTOR TO A VESSEL FOR DELIVERING MAGNESIA FINES, SULFUR DIOXIDE AND OTHER HOT EXHAUST GASES FROM THE REACTOR TO AMMONIA-BASE BISULFITE SPENT LIQUOR IN THE VESSEL; A CONDUIT FOR DELIVERING AMMONIA-BASE BISULFITE SPENT LIQUOR TO THE VESSEL; A CONDUIT FOR DELIVERING CONCENTRATED SPENT LIQUOR FROM THE VESSEL TO THE REACTOR FOR COMBUSTION OF THE LIQUOR THEREIN, AND MEANS TO ABSORB SULFUR DIOXIDE AND AMMONIA FROM THE VESSEL IN AQUEOUS AMMONIUM HYDROXIDE TO FORM FRESH AMMONIA-BASE BISULFITE PULPING LIQUOR.

Claim 3

Apparatus comprising: a fluidized bed reactor having a bed of magnesia particles; an exhaust gas conduit from the freeboard space of the reactor to a contactor vessel for delivering magnesia fines, sulfur dioxide and other hot exhaust gases from the reactor to the contactor; a separator for separating sulfur dioxide, ammonia, steam and other gases from spent liquor therein; a conduit from the separator to the contactor for delivering spent liquor from the separator to the contactor; a conduit from the contactor to the separator for delivering a mixture of spent liquor, magnesia and exhaust gases from the contactor to the separator; a conduit for delivering ammonia-base bisulfite spent liquor to the separator; a conduit from the separator to the reactor for delivering concentrated spent liquor containing magnesium-base bisulfite spent liquor from the separator to the reactor; and means to absorb sulfur dioxide and ammonia from the separator in aqueous ammonium hydroxide to form fresh ammonia-base bisulfite pulping liquor.

Claim 4

Apparatus comprising: a fluidized bed reactor having a bed of magnesia particles; an exhaust gas conduit from the freeboard space of the reactor to a contactor vessel for delivering magnesia fines, sulfur dioxide and other hot exhaust gases from the reactor to the contactor; a separator for separating sulfur dioxide, ammonia, steam and other gases from spent liquor therein; a conduit from the separator to the contactor for delivering spent liquor from the separator to the contactor; a conduit from the contactor to the separator for delivering a mixture of spent liquor, magnesia and exhaust gases from the contactor to the separator; a conduit for delivering ammonia-base bisulfite spent liquor to the separator; a conduit from the separator to the reactor for delivering concentrated spent liquor containing magnesium-base bisulfite spent liquor from the separator to the reactor; and means to absorb sulfur dioxide and ammonia from the separator in aqueous ammonium hydroxide to form fresh ammonia-base bisulfite pulping liquor.

Claim 5

Apparatus for producing ammonia-base bisulfite pulping liquor from spent ammonia-base bisulfite liquor while avoiding the emission of environment contaminants, comprising: a fluidized bed reactor having a bed comprising particles of magnesia and a freeboard space above the bed; a scrubber; means for contacting, in said scrubber, said spent liquor containing organics from wood, water and ammonium bisulfite with magnesia, sulfur dioxide and water, to form an aqueous solution of magnesium bisulfite and a gaseous mixture comprising ammonia and sulfur dioxide; means for burning said solution in oxygen in said reactor at a bed temperature of about 1,400* to 2,000*F. to produce exhaust gases comprising carbon dioxide, water vapor and sulfur dioxide; means for conveying said exhaust gases from the reactor to said scrubber as a source of said sulfur dioxide; means for conveying magnesia from said bed to said means for contacting; means for reacting said gaseous mixture with aqueous ammonium hydroxide to produce an aqueous solution of ammonium bisulfite as said ammonia-base pulping liquor; and means for venting unreacted gases from said means for reacting, said gases being innocuous and comprising carbon dioxide, water vapor and not more than a minute amount of unreacted sulfur dioxide.

Claim 6

Apparatus for producing ammonia-base bisulfite pulping liquor from spent ammonia-base bisulfite liquor while avoiding the emission of environment contaminants, comprising: a fluidized bed reactor having a bed comprising particles of magnesia and a freeboard space above the bed; a scrubber; means for contacting, in said scrubber, said spent liquor containing organics from wood, water and ammonium bisulfite with magnesia, sulfur dioxide and water, to form an aqueous solution of magnesium bisulfite and a gaseous mixture comprising ammonia and sulfur dioxide; means for burning said solution in oxygen in said reactor at a bed temperature of about 1,400* to 2,000*F. to produce exhaust gases comprising carbon dioxide, water vapor and sulfur dioxide; means for conveying said exhaust gases from the reactor to said scrubber as a source of said sulfur dioxide; means for conveying magnesia from said bed to said means for contacting; means for reacting said gaseous mixture with aqueous ammonium hydroxide to produce an aqueous solution of ammonium bisulfite as said ammonia-base pulping liquor; and means for venting unreacted gases from said means for reacting, said gases being innocuous and comprising carbon dioxide, water vapor and not more than a minute amount of unreacted sulfur dioxide.

Claim 7

The apparatus of claim 3 wherein said means for contacting comprises a scrubber, a separator, a conduit circuit interconnecting said scrubber and separator and means for circulating said spent liquor, magnesia, sulfur dioxide and water in said circuit.

Claim 8

The apparatus of claim 3 wherein said means for conveying magnesia from said bed to said means for contacting comprises means for mixing water with said magnesia after being withdrawn from the bed.

Claim 9

THe apparatus of claim 3 wherein said means for reacting comprises an absorption tower having means for conveying said aqueous ammonium hydroxide through the absorption tower and means for conveying said gaseous mixture to said absorption tower for reaction with said aqueous ammonium hydroxide therein.

Claim 10

The apparatus of claim 6 wherein there are provided means for circulating ammonium bisulfite solution from said absorption tower and back to said tower in a loop exteriorly of said tower, and means are provided for introducing said aqueous ammonium hydroxide into the absorption tower at a space above the ammonium bisulfite solution.

Claim 11

Apparatus for producing ammonia-base bisulfite pulping liquor from spent ammonia-base bisulfite liquor while avoiding the emission of environment contaminants, comprising: a fluidized bed reactor having a bed comprising particles of magnesia and a freeboard space above the bed; a scrubber; means for contacting, in said scrubber, said spent liquor containing organics from wood, water and ammonium bisulfite with magnesia, sulfur dioxide and water, to form an aqueous solution of magnesium bisulfite and a gaseous mixture comprising ammonia and sulfur dioxide; means for burning said solution in oxygen in said reactor at a bed temperature of about 1,400* to 2,000*F. to produce exhaust gases comprising carbon dioxide, water vapor and sulfur dioxide; means for conveying said exhaust gases from the reactor to said scrubber as a source of said sulfur dioxide; means for conveying magnesia from said bed to said means for contacting; an absorption tower having means for conveying said aqueous ammonium hydroxide through the absorption tower and means for conveying said gaseous mixture to said absorption tower for reaction with said aqueous ammonium hydroxide therein to produce an aqueous solution of ammonium bisulfite as said ammonia-base pulping liquor; means for venting unreacted gases as a mixture from said means for reacting, said gases being innocuous and comprising carbon dioxide, water vapor and not more than a minute amount of unreacted sulfur dioxide; a separator for separating liquid from said gaseous mixture; means for connecting said scrubber and separator in a liquid flow loop; a cooling tower between said absorption tower and the separator; means for flowing said gaseous mixture from said separator through said cooling tower and to said absorption tower; and means for circulating gases from said tower through a cooling heat exchanger externally of the cooling tower.

Claim 12

Apparatus for producing ammonia-base bisulfite pulping liquor from spent ammonia-base bisulfite liquor while avoiding the emission of environment contaminants, comprising: a fluidized bed reactor having a bed comprising particles of magnesia and a freeboard space above the bed; a scrubber; means for contacting, in said scrubber, said spent liquor containing organics from wood, water and ammonium bisulfite with magnesia, sulfur dioxide and water, to form an aqueous solution of magnesium bisulfite and a gaseous mixture comprising ammonia and sulfur dioxide; means for burning said solution in oxygen in said reactor at a bed temperature of about 1,400* to 2,000*F. to produce exhaust gases comprising carbon dioxide, water vapor and sulfur dioxide; means for conveying said exhaust gases from the reactor to said scrubber as a source of said sulfur dioxide; means for conveying magnesia from said bed to said means for contacting; an absorption tower having means for conveying said aqueous ammonium hydroxide through the absorption tower and means for conveying said gaseous mixture to said absorption tower for reaction with said aqueous ammonium hydroxide therein to produce an aqueous solution of ammonium bisulfite as said ammonia-base pulping liquor; means for venting unreacted gases as a mixture from said means for reacting, said gases being innocuous and comprising carbon dioxide, water vapor and not more than a minute amount of unreacted sulfur dioxide; a separator for separating liquid from said gaseous mixture; means for connecting said scrubber and separator in a liquid flow loop; a cooling tower between said absorption tower and the separator; means for flowing said gaseous mixture from said separator through said cooling tower and to said absorption tower; and means for circulating gases from said tower through a cooling heat exchanger externally of the cooling tower.