Process and apparatus for treating green liquor
OwnerPeter J. Flanagan, John B. Johnson, IIinventors
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Abstract
A method of and apparatus for treating a green liquor stream produced in a kraft pulp process to separate green liquor from dregs present in the stream by utilizing a filtration vessel that has a pressure differential between the green liquor inlet and outlet to drive the dregs from the green liquor. In addition, negative pressure is utilized in the filtration vessel to thereby drive water vapor from and consequently cool the filtered green liquor.
Claims19
A method of treating a stream containing green liquor and solid dregs that is produced in a kraft pulp process, comprising
- (a) directing the stream to a filter unit for filtering dregs from the stream having an inlet for the stream, an outlet for filtered green liquor and an outlet for dregs, wherein the unit has at least one filtration element and a pressure differential between the filtered green liquor outlet and the inlet, with the filtered green liquor outlet being maintained at a lower pressure than the inlet, to thereby facilitate the removal of dregs from the green liquor by filtration;
- and
- (b) maintaining that portion of the filter unit downstream from the filtration element at a negative pressure to thereby drive water vapor from and cool and concentrate the filtered green liquor.
A method of treating a green liquor stream produced in a kraft pulp process to separate green liquor from the stream for use in a recausticizing step to generate white liquor, comprising
- (a) directing the stream to a filter unit having a green liquor inlet and a green liquor outlet, wherein the unit has a pressure differential between the green liquor inlet and green liquor outlet to facilitate the removal of dregs from the green liquor by filtration, with the green liquor outlet being maintained at a negative pressure to thereby drive water vapor from and cool the filtered green liquor;
- (b) directing the filtered green liquor and water vapor to a separator vessel in which the vapor is separated from the green liquor;
- and
- (c) condensing the water vapor removed from the green liquor back into water.
Apparatus for use in a recausticizing process for separating green liquor from dregs comprising
- a filtration vessel containing a green liquor inlet and a green liquor outlet;
- means to maintain a pressure differential between the green liquor inlet and the green liquor outlet to facilitate the removal of dregs from the green liquor by filtration;
- means to maintain the green liquor outlet at a negative pressure to thereby drive water vapor from and cool the filtered green liquor;
- means to remove the filtered dregs from the filtration vessel;
- and
- means to remove the water vapor and the filtered green liquor from the filtration vessel.
Dependencies are inferred from the claim text.