| 摘要 |
A wood pulp slurry (17, 73, 123, 209) is treated with oxygen (89, 429, 212) in a mill with little change to the process or structure of the mill. No special pressure tanks are required. The consistency of the pulp need not be altered for the treatment step. It may be treated at the usual process consistency of the pulp; e.g.; it may be treated at the usual consistency of the pulp leaving a washer or subsequent steam mixer (86, 426, 206) without additional dewatering or additional dilution. The oxygen is added into a closed section of the system so that it cannot immediately vent to the atmosphere. Alkali (85, 425, 207) should also be present when the oxygen is mixed with the slurry. The mixing (88, 428, 211) should occur near to the point of oxygen addition. The pulp is treated with oxygen several times during a sequence. Some sequences are O-X-O and O-O-X-O in which X may be a hypochlorite, a peroxide or ozone, or chlorine, chlorine dioxide, combinations of chlorine (438) and chlorine dioxide (471), hypochlorite, peroxide or ozone. The sequence may be followed by a D stage (232). Specific mixer designs are also disclosed. |
