| 摘要 |
Cellulose waste liquors are worked up to recover sodium compounds as Na2CO3 and sulphur compounds as H2S by thermal decomposition of the liquor by bringing it together in a reactor with a concurrent stream of heated gas and separating the gaseous products from the other products, one portion of the gaseous products <PICT:0998467/C1/1> being subsequently heated indirectly by hot combustion gas whilst another portion is utilized as a component of the combustion gas. H2S in the gaseous products may be converted by combustion thereof to form SO2 either before or after removal from the gaseous products. In the specific embodiment, as shown, waste liquor is introduced into reactor 7 at 6 whilst hot gas previously heated in chamber 34 enters at 4. The reaction products leave reactor 7 at 8 and the solids are separated by cyclone 9, and passed to dissolving tank 29. A portion of the heated gas leaving cyclone 9 is fed to the reactor 7 through pipe 35 whilst the remainder is used to preheat air passing along pipe 2 to combustion chamber 34. H2S is removed from the gases at 18 by washing and the treated gas passed along line 19. One portion 19a is used as combustion gas together with air 2 and if required, fuel oil 1, in combustion chamber 34 whilst the other portion 19b is heated by the hot gases. H2S separated at 18 is passed to combustion chamber 24 where it is burnt with air 22 and if required, additional sulphur 23. SO2 so formed is passed to vessel 26 where it is contacted with sodium carbonate solution coming from tank 29 after filtration at 32, thus forming sodium sulphite cooking liquor. The use of an inclined reactor in the place of the vertical reactor is also mentioned. The reactor should preferably be run at below the ash fusion temperature e.g. less than 800 DEG F. The heated gas may be steam, CO2, CO, H2, N2 or mixtures thereof. |
