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Wilke C.,BTG | Wilke C.,Karlstad University | Andersson N.,BTG | Van Fleet R.,BTG Americas Inc. | And 2 more authors.
Tappi Journal | Year: 2016

While carryover of dissolved lignin between stages in the pulp mill fiber line is a well-known problem, it is still typically seen only as a minor disturbance factor or bias in the control of oxygen (O2) delignification and bleaching stages. The present study, however, reveals that it plays a larger role than anticipated, and that it should be properly analyzed in order to correctly control the process stages. This is especially important for the O2 and D0 stages as the lignin content is still high in these positions. The results of the study show that dissolved lignin carried over between stages may have a significant impact on the bleaching chemical consumption and, indirectly, on the pulp quality. Mill investigations have shown very large variations in the dissolved lignin content in the pulp before the oxygen delignification stage and before the D0 stage that have significantly influenced the bleaching chemical demand and, subsequently, the degree of delignification. In order to develop a better understanding of the mechanisms of the dissolved lignin's reactions, laboratory O2 and D0 experiments with controlled levels of dissolved lignin were conducted. It was anticipated that a better feedforward control could be achieved using an online dissolved lignin measurement, and results from mill trials are presented. Chlorine dioxide laboratory experiments using different levels of carryover (i.e., different dissolved lignin contents) were conducted. It was concluded that the filtrate kappa number provides a relevant measure of the bleach demand due to the dissolved lignin and that, subsequently, the combined fiber and filtrate kappa number provides an appropriate measure for optimum feedforward control of the stages. Mill results support these findings, which show that the chemical consumption is reduced significantly using the total kappa number. The post-D or post-DE kappa number feedback control can most probably be eliminated by using this technology. Source


Watzig D.,BTG | Haake P.,BTG Americas Inc. | Karras C.,Hamburger Rieger GmbH and Co. KG | Berger R.,BTG
O Papel | Year: 2014

At Hamburger Rieger Containerboard in Trostberg, Germany, one of the most critical success factors is to decrease raw material cost without compromising product quality. This is a challenge for the premium supplier of white top testliner as prices for waste paper raw material are increasing while, at same time, the quality of the recovered material decreases. However, the implementation of online measuring technology for retention and charge, eventually leading to automatic control of chemical additives, accomplished this goal. Optimization of additive dosages in the top layer led to reduced basis weight and increased sheet ash without affecting product quality. Actual mill data and a cost/benefit calculation will illustrate the outcome of the project, which was called "whiter lighter". The savings included less usage of fixative and retention aid chemicals. Furthermore, expensive furnish was replaced by less expensive filler. Source


Van Fleet R.,Honeywell | Dion M.,Honeywell | Beder-Miller S.,BTG Americas Inc.
International Pulp Bleaching Conference 2011, IPBC 2011 | Year: 2011

During the past two decades there have been significant changes to operating conditions of fiber lines and bleach plants, in particular. In addition to major mechanical modifications, environmentally driven changes have resulted in the elimination of chlorine for most Kraft bleached grades. However,many of the norms or control philosophies have not changed and are in fact rooted in the theories related to the characteristics of chlorine bleaching. Very small amounts of lignin remain in lower Kappa Number pulp entering the brightening stage. The traditional location of sensors needs to be changed as the reaction rates of chlorine dioxide are much different than chlorine. Brightness control becomes more appropriate than the traditional kappa factor control and evidence will be presented that shows DEK levels less than 2 have a high degree of testing error and potential variability when compared to a brightness measurement. Source


Demler C.L.,Kadant | Beder-Miller S.E.,BTG Americas Inc. | Aldridge R.,Atlantic Packaging Inc.
Paper Conference and Trade Show 2012, PaperCon 2012: Growing the Future - Co-located with Control Systems 2012 | Year: 2012

Low consistency refining is one of the few elements of a recycling system that can be used to strategically modify the fiber properties and enhance its paper making characteristics. Over the years, research has predominately been conducted on smaller pilot scale refiners however these machines are generally recognized to be much more efficient than larger commercial scale equipment resulting in uncertainty concerning the scalability of the results to commercial applications. Kadant Black Clawson has developed a number of patented technologies over the years while studying ways to achieve small lab type refiner precision from a commercially sized refiner. Recently, a commercial 42-inch diameter, 1000 hp, prototype refiner capable of lab refiner precision began operation and is currently being used to produce base ply refining for a 750 BDSTVD linerboard machine. This paper discusses the importance of refiner alignment, plate edge condition, freeness control, and other fundamentals as they apply to commercial refining and production improvements. The hope is that these lessons combined with those from previous research using lab scale refining can help the attendee optimize their own systems and controls. Source


Watzig D.,BTG | Hendricks M.,BTG Americas Inc. | Karras C.,Hamburger Rieger GmbH and Co. KG
Paper Conference and Trade Show, PaperCon 2013 | Year: 2013

In today's competitive market it is vital to make investments that continuously improve product quality and decrease production cost. At Hamburger Rieger Containerboard in Trostberg, Germany one of the most critical success factors is to decrease raw material cost. This is a challenge as prices for the waste paper raw material are increasing while at the same time the quality of the recovered material decreases. As a premium supplier for white top test liner, customer demands are high and product quality cannot be compromised. The objective of the customer was to apply online measuring technology of retention and charge leading to automatic control of chemical additives to achieve these goals. This paper will outline the optimization process by applying online measuring technology to the automation of additive dosages to achieve reduced basis weight and increased sheet ash without compromising product quality of the top layer. Actual mill data and a cost/benefit calculation will be provided to discuss the outcome of the project which was called "whiter lighter". The savings included less usage of fixative and retention aid chemicals. Furthermore, expensive furnish was replaced by less expensive filler. With higher filler content sheet printability was improved. Mill projects are usually characterized by particular goals defining the mill's requested outcome. However, very often the process reveals problems which are discovered during the project making it challenging for both parties. The project described in this paper could be finalized above its expectations due to the customer's willingness to work together. Source

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