2010年6月 紙パ技協誌

Vol.64, No.6 Abstracts

Energy Saving by Changing Control of Cooling Tower Fan

Yoshitaka Aoyagi
Kanto Mill (Katsuta), Hokuetsu Kishu Paper Co., Ltd.

  The reduction in the greenhouse gases emission is more important according to measures for controlling global warming. Therefore, the reduction in the amount of the fossil energy use and the approach on energy conservation are pressing needs. Our company also has executed various energy conservations enumerating all companies.
  In Kanto Mill (Katsuta), the commercial operation of the biomass power plant was begun from the purpose of reduction of CO2 emissions, the energy cost reduction and a superannuated update of the existing oil fired boiler in September, 2006. As a result, it greatly contributed to the reduction of CO2 emissions.
  To work on further reductions which pay attention to incidental facilities changed control of cooling tower fan. As a result, energy conservation became possible, it is introduced in here.

Anaerobic Treatment of KP Evaporator Condensates with UASB Process

Tomohiro Kiyokawa and Takaaki Tokutomi
Kurita Water Industries Ltd.
Ichirou Umeda and Hiroshi Ougiya
Mitsubishi Paper Mills Limited

  In field of wastewater treatment, anaerobic treatment is gradually introduced to reduce energy consumption and excess sludge. One more benefit is energy recovery as methane gas which can be used as energy source. The anaerobic treatment is introduced to treatment condensate from kraft pulp process, which contains high concentration of methanol. Methanol is easily biodegradable, but there are difficulties in stability of granule. In this work, pilot scale test with condensate from kraft pulp process was performed, and stability of granule was improved by new chemical addition.

Approach to Energy Saving by Gas Turbine Introduction

Makoto Hayakawa
Gifu Mill, Oji Paperboard Co., Ltd.

  The Nakatsugawa Mill is located in Gifu Prefecture, which stands for center of Japan and is manufacturing containerboard.
  We concluded agreements on pollution prevention with Nakatsugawa City. To keep agreements we are actively involved in environmental preservation, such as acquisition of ISO14001 certification, reduction of waste, prevention of air and water pollution, prevention of noise and vibration.
  Here, we introduce two energy saving examples. One is to replace fuel oil boiler and steam turbine to gas turbine co-generation system on June 2007. The other one is renewal of dryer hood on PM1.

Energy Saving by Improvement of Flow that Dissolves Dust

Satoru Suzuki
Asahikawa Mill, Nippon Paper Industries Co., Ltd.

  For the recovery boiler, it is preferable that black liquor is as high dry solids as possible, but the higher dry solids, the higher viscosity of black liquor and brings some problems such as plugging issue or unstable operation. In order to solve these problems, and to decrease power consumption, we had changed to dissolve the dust into 55% solids black liquor instead of heavy black liquor. As a result of it, we can keep the heating surface area more cleanly in the vacuum evapolater as well as energy saving in the black liquor process. In addition, dry solids of heavy black liquor has been improved.

Energy Saving of the Fan by Flat Belt Drive System

Kenichi Minowa
Mitsuya Fan Mfg. Co., Ltd.

  ECOFAN is new series of Mitsuya belt-driven fan. ECOFAN reduced 6-11% power in comparison with the V-belt driven fan by using the hyper flat belt drive system. ECOFAN has many merits(Ecology clean)else not to mention energy saving. Mitsuya introduce ECOFAN and example of the energy saving remodeling construction of fan in operation.

Electricity Saving Work

Masanori Azumano
Takaoka Mill, Chuetsu Pulp & Paper Co., Ltd.

  Recently, as environmental and global warming issues progress seriously, it is important for us to reduce the green house gas emission and as a company, energy cost saving is important issue as well. We are making effort to achieve high efficiency of using oil, steam, electricity and water by checking total unit cost. Accordingly we also established internally Energy managing committee which hold monthly meeting, site patrol and search energy site matters then settle the every kind of energy saving issues. Now taking this opportunity, we would like to introduce our Inverter frequency control system reported as QC activity together with operating site staff.

Saving Energy by Innovative Machines of Pulping and Screening System

Sumio Ito
Akita Mill, Nippon Daishowa Paperboard Co., Ltd.

  Our stock preparation system produces recycled pulp for liner board machine.
After No.1 line was installed in 1981, we have reinforced it to 1991 while recycled pulp increased and increased production of liner board machine. Today, we produce about 80% of recycled pulp for liner board machine. Our stock preparation system has three lines which are No.1 and No.2 line used 100% JOCC and No.3 line used JOCC and mixed waste paper. Then No.1 and No.2 line pulper was integrated in 2004 and this pulper was distributing recycled pulp to two lines of screen system.
  In this time, we introduce the case that we could achieve saving a big energy such as improving pulper outlet quality, reducing a number of screens afterward, stopping auxiliary equipment by simplification of the system flow and so on by introducing innovative machines between pulper and screen system in No.1 and No.2 line.

Energy Saving by Screen Upgrade in the OCC Process

Reiri Koga
Yodogawa Board Mill, Rengo Co., Ltd.

  Rengo established Eco Challenge 009 in 2001 as the companys environmental objective and has strenuously worked on energy saving, reduction of wastes and effective utilization of resource toward the year 2009, the 100th anniversary of the company.
  In order to strengthen the activity and set new environmental objectives, Eco Challenge 020 was established in 2009, the final year of the activity. In Eco Challenge 020, one of the targets is to reduce carbon emissions which is considered to have severe impact on the environment among the greenhouse gases. The goal of the company is to reduce the CO2 emissions level by 32% by year 2020 compared to the 1990 levels.
  The paper will introduce a case of energy-saving and industrial waste reduction at Yodogawa mill by installation of reject screen (HD screen supplied by Satomi Co., Ltd.) to upgrade the fine screen process of JOCC line.

A Report on Visit Pulp and Paper Industry in Europe after ABTCP Congress

Kunitaka Toyofuku

  I went across to Europe after participation for ABTCP Pulp and Paper International Congress & Exhibition was held in Brazil on October 26-29, 2009 and I visited the pulp and paper technology associations and the paper mills in Spain, Austria and Russia.
  The pulp and paper industries in these countries are unfamiliar for Japanese in comparison with Nordic countries and Germany, but there was characteristic in each country. I report about the contents.

Creation of Fine Paper from Hardwood Bleached Sulfate Pulp (part II)

Tsuneaki Kijima

  It will be covered in this latter part of the report, why has the paper from hardwood pulp become the main stream of the fine paper production.
  In April in 1952, the paper from the hardwood bleached sulfate pulp without any softwood pulp was produced for the first time in the world at Yufutsu mill in Hokkaido, overcoming lots of conventional beliefs. It had been thought for long time that the paper should be made from softwood pulp. But Mr. Mizuno and his partner Mr. Shimura believed to be able to make the paper from hardwood sulfate pulp excellent in its characteristics, in respects of those other than strength, if prepared properly in preparation stage of the pulp. As well known, in view of composition of the wood, the hardwood contains much hemicellulose which will behave as binder of the interfiber bonding that contributes to strength of the paper, and if cooked in sulfate process, much more hemicelluloses would remain in the pulp than cooked in sulfite process. In other words, the hardwood is able to put forth his value by the combination with the sulfate process. So, the paper from hardwood showed the strength equal to the paper from softwood sulfite pulp, in spite of its short fiber length. In addition, as expected by Mr. Shimura, shortness itself of the fiber length has brought to the paper many excellent characteristics, for instance sheet formation, bulkiness, stiffness, opacity and so on. Therefore, the paper from hardwood has earned high reputation in the market for usage of printing, wrapping and others. It was not long before this method started to be adopted actively in Japan, followed by the rest of the world. In addition, generally speaking, hardwood grows much earlier compared with softwood. Therefore, many large paper making companies are developing the afforestation estate aiming for self-sufficiency of the raw materials of the paper. It might be said that pulp and paper industry is on its way to sustainable ecological model attached with the progress of the biotechnology together.

Strength Restoration of Paper from Recycled Pulp by an Addition of a Polyacrylamide Dry
Strength Resin and Its Distribution within a Fiber Wall

Takushi Sakaemura
R&D Department, Paper Chemical Division, Arakawa Chemical Industries, Ltd.
Graduate School of Agriculture, Kyoto University
Tatsuo Yamauchi
Graduate School of Agriculture, Kyoto University

  In order to study the mechanism of strength restoration of paper from recycled pulp by means of an addition of a dry strength resin and its distribution within a fiber wall, papers with or without a commercially available cationic polyacrylamide resin (PAM) were prepared from hardwood and softwood bleached kraft pulps which were recycled through drying, rewetting and disintegrating up to 30 times. The increment of tensile strength caused by addition of PAM steeply increased up to 3 times recycling in spite of the almost same PAM content. And then the increment became nearly constant with a further increase of recycle number, although the total PAM content within the recycled sheets gradually decreased. Measurement of PAM content at the exact surface of fibers was determined with an electron spectroscopy for chemical analysis (ESCA). Further depth profiles of PAM within a fiber wall were determined by an attenuated total reflection Fourier transform infrared spectroscopy (ATR/FT-IR) combined with a sputter etching method. These results obtained by ESCA and the ATR/FT-IR with etching indicated that the PAM tended to be distributed nearby the fiber surface more than inner fiber wall with increasing recycle number. A decrease in scattering coefficient of the freeze-dried wet papers with increasing recycle number suggested a decrease in external fibrils projecting from the wet fibers, which was in accordance with SEM observation. The change in distribution of PAM within a fiber wall with recycling therefore should be attributed to the decrease in external fibrils caused by recycling, so that it should influence the increment of tensile strength by the contained PAM. These results suggested that the PAM located nearby the fiber surface would be significantly important for strength development by addition of PAM.

Keywords: Polyacrylamide, Dry strength resin, Recycled pulp, Handsheet, Distribution, Tensile strength, external fibril