Experiences of the Effect of New Shoe and Blade Type Initial Dewatering on Water Removal Efficiency and Paper Quality on a Full-Scale Production Machine

摘要

The main idea of this paper was to discuss the industrial verification of the novel shoe and the blade gap forming technology. This paper is a continuation of papers presented at PaperCon 2010, where the advantages of the aforementioned forming technology against conventional roll and blade forming technologies were discussed. The shoe and blade forming technologies differ from the conventional technologies in the way that the initial dewatering takes place, i.e. in terms of the initial dewatering speed and time delay between the initial dewatering and the loadable blade section dewatering. Due to this difference, it was believed (hypotheses 2010) that a type of consistency profile is generated inside the sheet, which emphasizes the effect of a shear force field generated with the speed difference between the wire and jet, and the loadable blades can thus further improve the sheet formation.. The previous results presented were based on pilot machine trial results. Several production machines have been started since the previous study. This paper presents a comparison of dewatering behavior between a roll and blade former and a shoe and a blade type gap former. Paper properties between these wet end concepts are compared as well. A similar improvement in the formation of the sheet internal layers was found in the pilot machine and in the production machines. Based on the production machine findings, it can be stated that the controlled drainage speed and the modified z-directional yield stress profile of a shoe-and-blade forming section is beneficial for paper quality and dewatering efficiency.