| 摘要 |
A method of integrating bleaching and recovery in connection with the produc tion of chemical pulp that has been digested and preferably delignified with oxygen gas using processes that retain the visco sity and strength, to kappa number less than 16 without the use of chemicals containing chlorine, and using a bleaching sequence includi ng at least one step with sequestering agent and/or acid , and a peroxide step. According to the invention spent liquor (5) from the bleac hing department is pre-evaporated in one or more evapora tion units (20F, 20G), and the spent liquor (24) from the bleaching department th us pre-evaporated is combined with spent liquor (22) fro m the digestery and/or with pre-evaporated spent liquor (23) from the digestery ob tained by pre-evaporating spent liquor (22) from the dig estery in one or more evaporation units (20D, 20E) other than said evaporation unit s (20F, 20G) for pre-evaporating spent liquor (5) from t he bleaching department, after which the mixture of spent liquors (23, 24) is s ubjected to final evaporation in one or more evaporation units (20A, 20B, 20C) other than said evaporation units (20F, 20G, 20D, 20E) used for pre-evaporation.
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