Impact of Sequence Position for Pressurized (Po) Stage in ECF Bleaching, 1995 Pulping Conference Proceedings

Richard Reeves

SundsDefibrator Inc.

Rolf Boman

Solveig Nordén

Sunds Defibrator AB

The proposed EPA regulations for discharge of bleach plant effluents will force many mills to modify their pulping and bleaching processes. In this paper we describe how the pressurized peroxide/oxygen, (PO), bleaching technology can be used to convert a chlorine based bleach plant to ECF without investing in additional C1O2 capacity. We further show that this technology can significantly reduce the C1O2 consumption in an existing ECF bleach plant. As a result the formation of AOX is significantly reduced. The (PO) stage can be installed in different positions in the sequence, as a second delignification stage, OQ(PO), replacing the first extraction stage, O(DQ)(PO), or as a final stage OD(EOP)D(PO). The (PO) stage can also be used for production of semibleached pulp with sequences such as (DQ)(PO) or Q(PO). In this paper the impact of (PO) sequence position on equipment layout, chemical consumption efficiency, bleach plant closure and flexibility for conversion to TCF are discussed.