| 摘要 |
<p>Pulping chemicals in an alkaline sulfite pulping process are recovered and steam is made by feeding spent liquor to gasification reactor; leaching solid residue; dissolving and causticizing remaining solid residue in water; combusting hydrogen sulfide-containing gas in steam boiler; absorbing sulfur dioxide in pure sodium carbonate solution; and removing carbon dioxide from solution. Recovery of pulping chemicals in an alkaline sulfite pulping process and production of steam, comprises: (a) feeding an evaporated spent liquor into a gasification reactor in which the liquor is decomposed into a hydrogen sulfide-containing gas and a solid residue contain sodium carbonate and a controlled concentration of sodium sulfide; (b) leaching the solid residue from the gasification reactor in a counter-current leaching process, which involves at least two stages comprising dissolving and separating soluble process-foreign elements, i.e. potassium and chlorine; and dissolving and separating sodium sulfide, sodium sulfate and a portion of the sodium carbonate present; (c) dissolving the remaining solid residue from the leaching process, in water; (d) filtering the resulting solution to remove non-soluble processing-foreign elements and any possible carbon residue and is treated in an oxidizing stage to give a substantially pure sodium carbonate solution; (e) causticizing the solution containing sodium sulfide, sodium sulfate and sodium carbonate that was separated in the second leaching stage, resulting in a sodium hydroxide-containing solution; (f) leading the hydrogen sulfide-containing gas from the gasification reactor through a dust collector and is combusted in a steam boiler, producing steam; (g) absorbing the sulfur dioxide generated in the steam boiler in the pure sodium carbonate solution resulting from the oxidizing stage ; and (h) removing carbon dioxide from the solution in a desorption stage to form substantially pure sodium sulfite solution.</p> |
