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Method and device for efficiently bleaching medium-concentration paper pulp through cooperation of ozone and chlorine dioxide
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A chlorine dioxide and ozone technology, applied in pulp bleaching, textile and papermaking, cellulose pulp post-treatment, etc., can solve the problems of high cost, dependence, and low pulp strength, reduce pollution load, and upgrade easily Efficient and synergistic bleaching effect
Inactive Publication Date: 2020-01-07
SOUTH CHINA UNIV OF TECH
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[0016] The invention solves the problems that the existing bleaching process is difficult to meet the environmental protection requirements of reducing the use of chlorine dioxide, reducing the generation of AOX, and reducing the pollution load, as
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Embodiment 1
[0080] Ozone and chlorine dioxide bleaching process:
[0081] (1) The slurry in the previous section enters the medium consistency standpipe 1, adding dilution water to adjust the quality pulp concentration to 12%, adding a certain amount of acid solution to adjust the pH to 3, and turning on the medium consistency pump 2 to transport the pulp.
[0082] (2) Ozone addition: open the first air inlet valve 10 to press in the ozone with an amount of 0.6%, and open the pre-mixer 3 to make the ozone and the slurry mix and react.
[0083] (3) Open the steam inlet valve 14 to add steam, and the steam and the slurry are mixed in the steam mixer 4 and heated to 60°C.
[0084] (4) Chlorine dioxide addition: open the chlorine dioxide inlet valve 13 to pump chlorine dioxide in an amount of 0.3%, and open the middle mixer 5 to make the chlorine dioxide and the slurry mix and react.
[0085] (5) Supplementary reaction: the slurry mixed with ozone and chlorine dioxide directly enters the ble...
Embodiment 2
[0102] Ozone and chlorine dioxide bleaching process:
[0103] (1) The slurry from the previous section enters the medium-consistency riser 1, adding dilution water to adjust the mass pulp concentration to 12%, adding a certain amount of acid solution to adjust the pH to 2, and turning on the medium-consistency pump 2 to transport the pulp.
[0104] (2) Ozone addition: open the first air inlet valve 10 to press in the ozone with an amount of 0.4%, and open the pre-mixer 3 to make the ozone and the slurry mix and react.
[0105] (3) Open the steam inlet valve 14 to add steam, and the steam and the slurry are mixed in the steam mixer 4 and heated to 60°C.
[0106] (4) Chlorine dioxide addition: open the chlorine dioxide inlet valve 13 to pump chlorine dioxide in an amount of 0.5%, and open the middle mixer 5 to make the chlorine dioxide and the slurry mix and react.
[0107] (5) Supplementary reaction: the slurry mixed with ozone and chlorine dioxide directly enters the bleachin...
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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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