Methods for the treatment of spent sulfite pulping liquors and the recovery of chemical pulping values therefrom

Abstract

Abstract IMPROVED PROCESSES FOR THE TREATMENT OF SPENT PULPING LIQUORS AND THE RECOVERY OF SULFITE VALUES THEREFROM WHEREIN THE DISCLOSURE SETS FORTH A FIRST METHOD CONSISTING ESSENTIALLY OF THE COMBINED PROCESS OF PYROLYZING AND TREATING IN A FLUIDIZED BED A SPENT NEUTRAL SEMI-SULFITE LIQUOR IN A SINGLE APPARATUS; THEN, TRANSFERRING THE GASEOUS PRODUCT TO A SEPARATOR FOR REMOVING ENTRAINED PARTICLES FOR RETURN TO THE FLUIDIZED BED WHERE THE PARTICLES ARE CONVERTED TO SODIUM CARBONATE FOLLOWED BY A REMOVAL OF THE SODIUM CARBONATE FROM THE BED FOR SCRUBBING GASES TO ABSORB SULFUR DIOXIDE TO PRODUCE SODIUM SULFITE, AND WHEREIN THE PROCESS FURTHER CONSISTS OF RECIRCULATING THE HOT GASES PRODUCED IN THE COMBINED PYROLYZING FLUIDIZED BED TREATMENT AFTER THE ENTRAINED PARTICLES HAVE BEEN SEPARATED IN THE CYCLONE SEPARATOR BY CONVEYING SOME OF THE GASES TO THE FLUIDIZED BED AND ALSO BURNING SOME OF THE GASES IN A FURNACE TO PRODUCE SULFUR DIOXIDE, WHICH IS THEN ABSORBED IN A SOLUTION OF SODIUM CARBONATE FROM THE FLUIDIZED BED TO PRODUCE SODIUM SULFITE. THE SECOND PROCESS DESCRIBED IN THE INVENTION RELATES TO PYROLYZING A SPENT LIQUOR IN A PYROLYZING CHAMBER FOLLOWED BY SEPARATING THE ENTRAINED PARTICLES IN A CYCLONE SEPARATOR AND CONVEYING SAID SEPA- RATED PARTICLES TO A MULTISTAGE FLUIDIZED BED TO PRODUCE A SOLID PRODUCT CONSISTING PRIMARILY OF SODIUM CARBONATE AND GASEOUS PRODUCTS, WHICH GASEOUS PRODUCTS ARE CONVEYED FROM THE FLUIDIZED BED TO THE PUROLYZING CHAMBER FOR TREATMENT OF THE INCOMING SPENT PULPING LIQUOR. THE GASES PRODUCED IN THE PYROLYZING CHAMBER ARE CONVEYED FROM THE CYCLONE TO A RECIRCULATING SYSTEM WITH SOME OF THE SAID GASES BEING TRANSPORTED BACK INTO THE PYROLYZING CHAMBER MIXED WITH THE GASES FROM COMBUSTION OF THE SOLID PARTICLES ENTERING THE FLUIDIZED BED FROM THE CYCLONE, AND THE REMAINING GASES TRANSPORTED TO A RECOVERY BOILER FOR CONVERSION OF THE SULFUR COMPOUNDS TO SULFUR DIOXIDE, WHICH IS THEN SCRUBBED WITH A SOLUTION OF SODIUM CARBONATE FROM THE FLUIDIZED BED REACTOR, FOR REGENERATION OF SODIUM SULFITE FOR PREPARATION OF A PULPING LIQUOR. IN BOTH OF THESE PROCESSES, THE RECIRCULATION OF THE PYROLYTIC GASES INTO THE PYROLYSIS CHAMBER AIDS IN MAINTAINING AN IMPROVED, MORE EFFECTIVE AND ECONOMICAL PYROLYSIS SYSTEM.

Inventors

• 👤 Philip E Shick

Bibliographic Details