Wet-strength waste paper recycling chemical mechanical pulping system

Abstract

The invention discloses a wet-strength waste paper recycling chemical mechanical pulping system. In the material process running direction, the system comprises first conveying equipment, a crusher, second conveying equipment, a tumbler-type washing machine, an oblique spiral dehydrator, a steaming bin, a third spiral conveyer, a first double-screw impregnator, a first reaction bin, a fourth spiral conveyer, a second double-screw impregnator, a second reaction bin, a fifth spiral conveyer, a latency chest, a pulp pump, a fiber separator, a purification, filtration and concentration device and a pulp storage device. The uniform-discharging-type reaction bins are used for achieving uniform discharging so as to reduce the load fluctuation amplitude; the rotary material-poking-type steaming bin is used for eliminating the bridging phenomenon, sufficiently steaming materials so as to soften the materials and reducing chemical consumption; the double-screw impregnators are used for dissociating wet-strength waste paper gradually, achieving high-concentration mixing and homogeneous immersion of chemical agents and pulp and improving the chemical reaction efficiency. The problems that when the wet-strength waste paper is recycled for pulping, the dissociation rate is low and the strength is greatly reduced are solved through the effects of mechanical strength and chemical treatment.

Description

technical field [0001] The invention relates to a pulping system and a pulping method, in particular to a waste paper recovery and reuse chemical mechanical pulping system and pulping method. Background technique [0002] Waste paper is an important fiber raw material for papermaking. All countries attach great importance to the recycling of waste paper resources. The world's waste paper recycling volume increased from 182.6 million tons in 2005 to 223.4 million tons in 2010; the recovery rate increased from 49.8% to 56.6%. , developed countries generally exceed 60%, and South Korea and Germany exceed 80%. my country's waste paper pulping increased from 28.1 million tons in 2005 to 53.05 million tons in 2010, and its proportion in the total pulp consumption increased from 54.0% to 62.7%, of which domestic waste paper pulp increased from 27.8% to 38.0%. During the "Twelfth Five-Year Plan" period, the increase in waste paper pulp is about 14 million tons. The domestic waste ...

AI Technical Summary

Problems solved by technology

The disadvantages of this technology are (1) the production of high-consistency pulp is discontinuous and takes a long time; (2) the power consumption is high; (3) the wet strength agent has not been chemically treated, which will cause Re-flocculation affects paper making; (4) The presence of wet strength agents will affect the use of other chemicals such as resident additives during paper making

Existing problems: (1) The yield of waste paper pulp is low, and a large amount of fiber raw materials are degraded and enter the pulping wastewater, which increases the difficulty and cost of wastewater treatment; (2) If the dissociated waste paper pulp is not bleached, the pulp whiteness It is very low and can only be used in some paperboards that do not require high whiteness, and the use of pulp is limited; (3) The chemical cooking method has a strong chemical effect on waste paper pulp, resulting in a decrease in the degree of cellulose polymerization, which leads to a physical breakdown of the pulp. decrease in strength

[0013] Existing problems: hypochlorite treatment can effectively treat bleached PAE wet-strength paper, and the cost is low, but it cannot completely repulp non-bleached wet-strength paper, and it will increase the amount of chloroform and tetrachloride in the discharged sewage. Loading of adsorbable organic halides (AOX) such as ethane, which is also a negative factor limiting the use of hypochlorite

[0017] Problems: During the neutral or alkaline repulping process, because the free radicals generated by the decomposition of peroxodisulfate can extract the hydrogen on the lignin to form non-reactive free radicals, so that most of the wet strength resins are not damaged. Oxidation, therefore, peroxodisulfate is not very effective for unbleached kraft pulp, chemical thermomechanical pulp and OCC wet strength paper, which is difficult to repulp

Although an excess of peroxodisulfate can overcome this side reaction, it is too expensive, inefficient and damaging to the fiber

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