FLUIDIZED PROCESS FOR REGENERATION OF CHEMICALS FROM SULFITE PULPING PROCESS

• US 3,711,593 A
• Filed: 08/12/1971
• Issued: 01/16/1973
• Est. Priority Date: 06/04/1969
• Status: Expired due to Term

• Current Assignee: OI Forest Products STS Incorporated (KOCH Industries Incorporated)
• Original Assignee: Philip E. Shick, William H. Flood
• Inventors: Shick, Philip E., Flood, William H.
• Primary Examiner(s): Peters, G. O.
• Application Number:
  US05/171,308
• Time in Patent Office: 523 Days
• Field of Search: 23/48,129,63 162/30
• US Class Current: 423/207
• CPC Class Codes: C01B 17/60 Isolation of sulfur dioxide from gases
• CPC Class Codes: C01B 17/62 Methods of preparing sulfites in general particular individual sulfites, see the relevant groups of subclasses C01B - C01G, according to the cation
• CPC Class Codes: C01D 7/00 Carbonates of sodium, potassium or alkali metals in general
• CPC Class Codes: D21C 11/127 with post-combustion of the gases
• CPC Class Codes: Y10S 159/03 Fluidized bed
• CPC Class Codes: Y10S 423/03 Papermaking liquor

Abstract

A method for regenerating a sodium base sulfite cooking liquor by utilizing a multi-stage fluid bed treatment. In the method for regenerating the liquor, the spent liquor is first treated in a fluid bed reactor with gases containing water vapor and carbon dioxide at a temperature less than 1100*F., to pyrolyze the liquor solids, to gasify the sulfur in the liquor and to produce a pelletized solid residue consisting of primarily sodium carbonate and carbon. This residue is then treated with air and water at a temperature greater than 1100*F. in a second fluid bed reactor to produce a solid product consisting primarily of sodium carbonate and gases suitable for use in the first reactor. The gaseous products of the first reactor are further oxidized with air to convert sulfur compounds to sulfur dioxide, which is then absorbed in a solution of sodium carbonate from the second reactor, thus regenerating sodium sulfite for preparation of pulping liquor.

Claims

2. treating the solid product of the first stage in a second stage fluid bed with air and water at a temperature greater than about 1100* F. to provide a solid sodium carbonate product and gases containing CO2 and water vapor that are suitable for use in the first stage,

3. In a method of regeneration of cooking chemicals from spent, semi-chemical, neutral sulfite pulping liquors, wherein said method consists essentially of the steps of:

reacting the spent liquor in a first stage spouted fluidized bed reactor with reducing conditions and a temperature not substantially greater than about 1100* F. to provide gaseous products that remove sulfur therein, and to provide a solid product;

maintaining fluidization in the spouted bed by recirculation of the bed particles to reduce stickiness of the particles;

reacting the solid product of the first stage reactor in a second stage fluidized bed reactor with air and water to remove carbon and provide sodium carbonate as the solid product;

reacting the sulfur containing gases from the first stage reactor with air to form a gaseous product containing sulfur dioxide; and

scrubbing of the gaseous product with a solution of sodium carbonate to form sodium sulfite for reuse as a pulping liquor.

4. scrubbing the oxidized gaseous products of step (3) with an aqueous solution of sodium carbonate of step (2) to provide a sulfited cooking liquor.

5. A method of regeneration of cooking chemicals from spent, semi-chemical, neutral sulfite pulping liquors, the method comprising the steps of:

A. reacting the spent sulfite liquor in a first stage spouted fluid bed under reducing conditions with gases containing carbon dioxide and water vapor with sufficient recirculation within the bed to provide fluidization to provide the reaction without the balling up and stickiness of the bed particles, to convert the sulfur in the spent liquor into gaseous products and to provide a solid residue product consisting essentially of sodium carbonate and carbon, B. treating the solid product of step (A) in a second stage fluidized bed reactor with air to remove the carbon from the solid product, C. oxidizing the sulfur in the gaseous products of step (A) to sulfur dioxide, and D. scrubbing the oxidized gaseous products of step (C) with a solution of sodium carbonate to form sodium sulfite for reuse as a pulping liquor.

6. A method as defined in claim 5 in which the reacting in step (A) is conducted at a temperature less than about 1100* F.