| 摘要 |
There is disclosed a process and a plant for bleaching cellulosic materials by aid of ozone. A concentrated solution of ozone in an aqueous medium (strong water) is supplied under pressure to the materials suspended in an aqueous medium and is mixed therewith in a mixing device. The mixture is conducted through a reaction vessel, the bleached material is separated from the bleaching liquor, and possibly present residual ozone is destroyed. The plant includes an arrangement for preparing a pulp suspension, at least one bleaching tower to receive the mixture of pulp suspension and concentrated ozone solution, an arrangement for producing an ozonic gas, filtering means, pumps and ducts for connecting the plant parts. The arrangement for producing ozone is flow-connected with an absorption column for preparing the concentrated ozone solution and a mixing arrangement is provided for mixing the pulp suspension with the concentrated ozone solution. The mixing arrangement is connected with the absorption column via a strong water duct. The absorption column, the mixing arrangement and the bleaching tower are equipped with means for generating and adjusting an overpressure.
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