Claims
- 1. A process for increasing the capacity of a spent pulping liquor recovery furnace, which comprises:
- (a) forming an unoxidized strong spent pulping liquor stream and dividing the stream into first and second unoxidized strong spent pulping liquor streams;
- (b) partially-oxidizing and evaporating said first strong spent pulping liquor stream, said partial-oxidation step being conducted employing oxygen, or a mixture of oxygen and an inert gas, so that the amount of bicarbonate material produced during said partial-oxidation is minimized, a partially-oxidized spent pulping liquor being produced having an increased total solids, and a gross heating value which is at least twenty percent less than the gross heating value of said second unoxidized strong spent pulping liquor stream without significantly increasing the viscosity thereof;
- (c) adding said partially oxidized evaporated spent pulping liquor either to the second stream and then concentrating the mixture, or to the second stream after the second stream has been concentrated to form a partially-oxidized, concentrated, high total solids spent pulping liquor product having a substantially lower gross heating value than, but a substantially similar viscosity as, said second unoxidized spent pulping liquor stream, said heating value being at least about 3400 BTUs/pound of liquor, said product, upon combustion in said furnace, significantly increasing the effective capacity thereof.
- 2. The process of claim 1, wherein said unoxidized strong spent pulping liquor stream is formed by initially evaporating a stream of unoxidized weak pulping liquor.
- 3. The process of claim 2, wherein said weak unoxidized spent pulping liquor is divided into respective first and second weak spent pulping liquor streams, prior to said initial evaporation step, said first liquor stream being subjected to said initial evaporation step, and second weak liquor stream being subsequently combined with said first strong spent liquor stream, prior to said partial-oxidation step, and the combined spent pulping liquor stream being subjected to said partial oxidation step.
- 4. The process of claim 1, wherein said second unoxidized strong spent pulping liquor stream is first concentrated, and is thereafter combined with said partially-oxidized spent pulping liquor stream.
- 5. The process of claim 1, wherein the pH of the partially-oxidized spent pulping liquor is at least about 10.
- 6. The process of claim 1, wherein the increase in the effective capacity of said recovery furnace is at least about 10%.
- 7. The process of claim 1, wherein the viscosity of the partially-oxidized, evaporated spent pulping liquor is substantially the same as, or less than, the viscosity of the unoxidized spent liquor to which it is added.
- 8. The process of claim 1, wherein the gross heating value of said partially-oxidized, evaporated liquor is at least about 50 percent less than the gross heating value of the unoxidized liquor to which it is added.
- 9. The process of claim 1, wherein the total solids of said partially-oxidized, concentrated liquor is from about 65 weight percent up to about 75 weight percent.
- 10. The process of claim 1, and wherein the partial-oxidation is carried out in a closed system and the formation of bicarbonate is minimized in the partial-oxidation step by the removal of carbon dioxide from said system.
Parent Case Info
This is a continuation of co-pending application Ser. No. 592,032 filed on Mar. 21, 1984, now abandoned.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
3714911 |
Pradt |
Feb 1973 |
|
3873414 |
Rocher et al. |
Mar 1975 |
|
4441959 |
Empie, Jr. et al. |
Apr 1984 |
|
Non-Patent Literature Citations (2)
Entry |
Grace "The Impact of Black Liquor Oxidation on Total Energy"; vol. 60, No. 11, Nov. 1977 Tappl; pp. 132-135. |
Grace "Increasing Recovery Boiler Throughput"; Tappl, vol. 67, No. 11, pp. 52-58. |
Continuations (1)
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Number |
Date |
Country |
Parent |
592032 |
Mar 1984 |
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