Method and device for efficiently bleaching medium-concentration paper pulp through cooperation of ozone and chlorine dioxide

Abstract

The invention discloses a method and a device for efficiently bleaching medium-concentration paper pulp through cooperation of ozone and chlorine dioxide. The device comprises a DCS control system, and a medium-concentration vertical pipe, a mixing unit and a bleaching tower which are connected successively. In treatment process adopting the method and the device, ozone can mostly replace chlorinedioxide, so that AOX in bleached wastewater is greatly reduced, the pollution load of wastewater treatment is reduced, and residual organic chloride in bleached pulp is reduced; due to the strong oxidizing property of ozone and the high selectivity of chlorine dioxide, lignin and chromophoric groups of to-be-bleached pulp with different characteristics can be removed in a targeted manner throughflexible synergistic cooperation, so that paper pulp with high whiteness, high strength and low kappa number is obtained; ozone is taken as a gaseous bleaching agent, and the adding position of ozonein an existing chlorine dioxide bleaching section is flexible and adjustable; compared with low-concentration or high-concentration paper pulp bleaching, advantages are that ozone and chlorine dioxideare synergistically mixed with turbulence-state medium-concentration paper pulp more uniformly, mass transfer is more efficient and rapid, the whiteness of bleached pulp is uniform and stable, and water and energy are saved.

Description

technical field

[0001] The invention relates to the technical field of pulping and papermaking, in particular to a method and device for synergistically and efficiently bleaching medium-consistency pulp with ozone and chlorine dioxide. Background technique

[0002] With the increasingly stringent environmental protection policies in our country, pulp and paper bleaching technology continues to develop. In recent years, my country has clearly proposed to promote clean production technology, prevent and control pollution, accelerate the widespread application of ECF elemental chlorine-free bleaching and TCF chlorine-free bleaching technologies, and greatly reduce the dioxins contained in bleaching wastewater produced by traditional chlorine-containing bleaching processes. and other strong carcinogens and refractory pollutants such as organic halides AOX.

[0003] At present, ECF elemental chlorine-free bleaching technology has been widely used in various large-scale pulping en...

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