Problems and measures in the production of ordinar

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Problems and measures in the production of ordinary cardboard from waste cardboard

the waste paper treatment process for the production of ordinary cardboard and brown cardboard from waste cardboard is as follows: waste cardboard - hydraulic pulper - Cylindrical desander - CX screen - single disc mill - thickener - pulp 4. Touch key operation mode pool - paperboard copying

in production, the round paper machine often appears paste, because it is involved in the industry and widely breaks paper. Now the upper and lower temperature tension testing machine should be re tensioned when it is found to be loose. The testing time is 15 seconds when the testing machine is turned on, which has a serious impact on the normal operation of production. Therefore, after careful analysis of the above problems, we found the problem, took certain measures, and achieved good results

1. Problems and reasons

1.1 paste: after the waste cardboard is dredged by the hydraulic pulper, part of the ink printed on the surface of the cardboard is free in the pulp, and the other part is still stuck to the fiber. Part of the dispersed ink dissociated in the pulp can be washed away when it is dehydrated by the circular thickener, but some of it still enters the waste of the paper machine and accumulates on the surface with the progress of production. At the same time, the ink also adheres to some fine fibers and dust, making the round eye smaller until paste occurs. After pasting, you can clearly see many longitudinal thin dry marks on the paperboard, and the spacing of each dry mark is equal to the wheel spacing, which seriously affects the appearance quality of the paperboard. The temporary treatment method is steam washing. Although the paste phenomenon improved temporarily after washing, with the increase of ink adhesion in the operation of the paper machine, the above paste phenomenon appeared soon, which had an adverse impact on the normal operation of production

1.2 paper breaking: due to the lack of strict Desanding, the pulp contains dust blankets, resulting in poor dehydration of the pressing part, and the moisture of the wet paperboard entering the dryer is high, which not only reduces the strength of the wet paperboard, but also increases the steam consumption of the dryer. In addition, the high content of ink and sediment in pulp also reduces the binding force between wet paperboard fibers. Therefore, cylinder sticking and even paper breaking often occur

1.3 paper blackening: when the printing ink dispersed in the wet paperboard is dried in the dryer, the ink accumulates with the reduction of moisture and disperses on the paperboard with the escape of water vapor, forming many small ink dots on the paperboard. After calendering by the calender, these small ink dots form black prints on the paperboard, affecting the appearance quality of the paperboard

2. Measures taken

the root cause of paper pasting, paper breaking and paper blackening is the high content of ink and sediment dust in pulp. First, when the waste cardboard is dredged, we add positive% sodium carbonate into the hydraulic pulper and inject steam to control the temperature of the pulp in the hydraulic pulper at about 80 ℃, so that the ink is fully saponified and dispersed in the pulp, which is removed together when the circular thickener is dehydrated; Secondly, the internal force of the slurry storage tank behind the cylindrical desander. Alum with human traffic volume, as the adsorbent for deinking, also adsorbs the sediment in the pulp and plays the role of water purification; Moreover, a 606 type conical desander is added behind the CX screen for further Desanding, and the slag discharge rate is controlled below 5%. After taking the above measures, the paste phenomenon of the round paper machine cage was basically eliminated, the dehydration of the paper machine pressing part was strengthened, and the service life of the blanket was prolonged. There were few cylinder sticking and paper breaking phenomena in the drying cadres, and the dry marks and black marks on the paper surface also basically disappeared

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