| 摘要 |
PCT No. PCT/SE84/00132 Sec. 371 Date Nov. 20, 1984 Sec. 102(e) Date Nov. 20, 1984 PCT Filed Apr. 13, 1983 PCT Pub. No. WO84/04114 PCT Pub. Date Oct. 25, 1984.The invention relates to a process for the washing of pulp with a maximum recovery of energy, the pulp after digestion being washed in a plurality of successive washing steps at a pressure above atmospheric in at least one of the steps and washing filtrate from a following step or fresh water being used as diluting and washing liquid in a given step. The outgoing washing filtrate from a washing step should be heat exchanged against incoming diluting and washing liquid to the subsequent step and a part of the filtrate (21) from the second step should be heat exchanged against washing filtrate (10) from the first step and then be combined with cooking liquor (23) for the digestion of the pulp. As diluting and washing liquids in the last two steps (4, 5), fresh water is used, which has also been heat exchanged against outgoing washing filtrate (54, 10) from the last and the first washing step. The gases leaving the washing steps are heat exchanged (25, 36, 47) against fresh water, which is then used as the diluting and washing liquid in the last step, the gases (11) from the first step however being heat exchanged against cooking liquor (8) for the digestion process. The condensates (13, 27) obtained from the heat exchange of the gases in each step are combined with the diluting liquid to the following step except for the steps in which fresh water is used as the diluting liquid. The resulting uncondensable gas fractions after the heat exchange are combined (59) and are finally heat exchanged once more (60) against incoming fresh water (57). The pulp (6) obtained from the digestion process is also (7) heat exchanged against the cooking liquor (8) which is led to the digestion process. |
