Abstract Black liquor is oxidized in a sinuous pipe or duct oxidizer, by dispersing an oxygen-containing gas into the continuous black liquor phase flowing within the duct. The gas is passed into the black liquor at spaced intervals, and the resulting dispersion of gas in oxidized black liquor is discharged into a vessel or other container below the level of the body of liquor in the vessel. Fully oxidized black liquor is removed from the vessel at a regulated rate, so as to maintain the level of liquor in the vessel, and oxygen-depleted gas is also removed from the vessel. The oxygen-depleted gas removed from the vessel may contain residual foam or entrained liquid droplets. In this case, the gas is passed through a mechanical foam breaker or a cyclonic gasliquid separator, with separated black liquor being recycled to the vessel.
The apparatus of claim 1, in which said first and said second straight linear ducts are horizontal.
Claim 2
Dependent Claim
22 words
The apparatus of claim 1, in which said first and said second straight linear ducts are disposed in a common horizontal plane.
Claim 3
Dependent Claim
17 words
The apparatus of claim 1, in which said curved duct is in the form of a semi-circle.
Claim 4
Dependent Claim
24 words
The apparatus of claim 1, in which said oxygen-containing gas is selected from the group consisting of air, oxygen-enriched air and substantially pure oxygen.
Claim 5
Dependent Claim
42 words
The apparatus of claim 1, combined with a mechanical foam breaker, means to pass said oxygen-depleted gas stream containing entrained foam through said mechanical foam breaker, and means to recycle the resulting liquid separated from said oxygen-depleted gas stream to said vessel.
Claim 6
Dependent Claim
42 words
The apparatus of claim 1, combined with a cyclonic gas-liquid separator, means to pass said oxygen-depleted gas stream containing entrainEd liquid droplets through said cyclonic separator, and means to recycle the resulting liquid separated from said oxygen-depleted gas stream to said vessel.
Claim 7
Dependent Claim
51 words
The apparatus of claim 1, in which said first and said second plurality of pipes terminate respectively within said first and said second duct with curved extensions, whereby said oxygen-containing gas is discharged from said pipes and centrally dispersed into said liquid within said ducts in the direction of liquid flow.
Claim 8
Dependent Claim
19 words
The apparatus of claim 1, in which said liquid is black liquor derived from the processing of wood pulp.