2004年7月 紙パ技協誌

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JAPAN TAPPI JOURNALVol. 58, No.7

July 2004    Abstracts


Effluent Minimization in European and North American Pulp and Paper Industries−Major Incentives for Mills to Reduce Water Consumption−
Hiroshi Araki
Japan Pulp and Paper Research Institute. Inc.

  Environmental regulations and economics have increased interest in minimizing water use and effluent discharge in the world. The reduction of water use by pulp and paper industries is mainly driven by environmental regulation and cost saving. Although our water consumption has decreased considerably during the last decade, we are still large users of fresh water in comparison to other manufacturing industries. A good water management allows us to reduce the water consumption without any increase in toxicity and affection to the processes or the quality of the final products.
  US pulp and paper industry discharged 53m3/adt of effluent in 1999. This represents a 40 percent reduction as compared to 1975. Continuous progress has been made by the Canadian industry in reducing water use. The average discharge is 66m3/adt presently. Current design levels for new mills in the newsprint and bleached kraft sectors are about 15m3/adt and 50m3/adt, respectively. The average discharge of EU pulp and paper industry is 35m3/adt presently and show the decrease of 19m3/admt (35%) during recent 5 years.
  In Japan the national average of effluent discharge by the pulp and paper industry is about 90m3/adt in 2001. Although the effluent volume has been decreased 75m3/admt (45%) since 1980, there are still opportunities for further reduction on water use and effluent discharge.
  This paper provides a summary of the effluent minimization implemented in European and North American pulp and paper industries during the 1990s.

Keywords : Effluent minimization, Environmental regulation, Water consumption, Effluent discharge, Bleached kraft pulp mill, Toxicity.


Operating Conditions of High Pulp Consistency Ozone ECF Bleaching
Shuuichiro Mochizuki
Nichinan Mill, Oji paper Co., Ltd.

  High pulp consistency ozone ECF bleaching plant was started up at Nichinan mill in 2002. This bleaching system is the first one in Japan. The operation is now stable through the solution of a couple of troubles during starting stage.
  Since we found that the pulp consistency and pH would be effect on the reaction efficiency on ozone stage, they have been carefully controlled as key factors.
  There would be almost no difference on pulp quality between ozone ECF and chlorine bleaching. The paper quality and runnability of paper machine seems to be same in both cases.
  The content of AOX and chloroform in effluent has been remarkably reduced, by >90% and >99%.


The Present Condition of Filtrating and a Future Plan of BKP Process
Toshihiro Kaketaka
Nomachi Mill, Chuetsu Pulp & Paper Co., Ltd.

Nomachi mill has 2 continuous cooking lines for Softwood (N) Pulp or Hardwood (L) Pulp respectively, and each process has individual bleaching system as well. As far as N pulp is concerned we produce both high Kappa-No. pulp for Kraft paper and low Kappa-No. pulp for bleached pulp base paper.
 This time, from the viewpoint of water-savings, I take up the washing flow of bleaching process as an example of BKP Filtrating.
 We use Drum Filters as the washer of bleaching line for both N and L. As for bleaching sequence we adopt the conventional one, that is to say L is C/D-E/O-H-D and N is C-EP-H-D. And we appropriate the filtrate of the last stage (H & D) to the shower of the fist stage effectively.
 I explain such a present condition of washing flow and the point of improvement after strengthening the H2O2 Bleaching line for N pulp, and also introduce the plan of ECF for N pulp that is to be changed from the conventional bleaching process this April.


Operating Experience of Bleaching Plant in #5KP−Improvement of Mill Water Consumption Rate by Increased Capacity−
Yasuhiko Nishiguchi
Iwakuni Mill, Nippon Paper Industries Co., Ltd.

A kraft pulp production line at Nippon Paper Iwakuni Mill, #5KP, was rebuilt in 1994 and has been operating well. The new line, originally designed as 1200 daily metric tons for bleached hardwood pulp, has three bleaching stages, C-E/H-D, each with a Diffuser Washer to intend energy saving. Since the start-up we have focused on improving the washing efficiency and reducing water consumption.
 Although the water consumption rate had been improved with increasing the production, we had difficulty in the bleaching efficiency and productivity due to scale trouble on the Diffuser Washer screens. A chemical washing to those screens was effective in removing calcium scale. Furthermore we found a method to prevent the scale by dosing caustic soda to washings on the secondary stage of the Diffuser Washer. (Pat.) These approaches have led to improvement of bleaching efficiency and expansion of production; 1450 mtpd in 1999, 1550 mtpd in 2002. As the result of increase in productivity, the water consumption rate in bleaching process has been significantly improved.

Keywords:Water consumption rate, Diffuser Washer, scale trouble


The Instances of Water Saving in Niigata Mill
Takeshi Sato
Hokuetsu Paper Mills Ltd., Niigata Mill

Hokuetsu Niigata Mill started up the new coated paper machine (PM8) in July 1998. To reduce the purchase of market hardwood pulp for PM8 and other upgraded machines, the increase of pulp production capacity and the modernization of the pulp plant were planned and carried out before PM8 was started up.
 This new pulp plant introduced ECF bleaching with D0-EP-DnD as a sequence. One of the most important thing was to reduce the use of water for this modernization.
 This article describes some instances of water saving at the pulp plant in Niigata mill.


Operating Experience of Partial Closure in ECF Bleaching
Masami Furui
Hachinohe Mill, Mitsubishi Paper Mills Limited

New ECF bleaching sequence introducing pretreatment stage (QX), pretreatment with a mixture of chelating agent (Q) and xylanase (X), was developed to allow the recovery of bleached effluent from several bleaching stages in Hachinohe Mill of Mitsubishi Paper Mills. The sequence was (QX) P1HP2D. The filtrates from (QX) stage and P1 stage were recovered and introduced to the mill recovery cycle.
 Before implementing the mill trials with new sequence, the balance of metals in the process was investigated. Most of the metals flowed in from the wood chips. The metals that flowed in the recovery cycle were discharged as the dregs. However, because the removed rate as the dregs was low about silicon and aluminum, their accumulate in the process concerned.
 By the recovery of bleached effluent, the concentration of metals in the black liquor increased a little .

Keywords:ECF bleaching, Pretreatment stage, chelating agent, xylanase, filtrate, partial closure, recovery cycle


Introduction of Effective Utilization of Water in the Kraft Pulp Factories
Yuji Tsukamoto
Ebara Corporation, Environmental Engineering Group

Recently, the paper factories within the country have shown the trends of merger and abolition and the surviving factories have been in the direction toward increasing in production. Therefore, and due in part to the expanded demand for wastepaper, the water situation around the paper factories stands, in general, facing a severe condition. The precondition for increasing in production is that there is an allowance for water usage, and therefore, for each factory, it is becoming an important theme to reduce the specific water consumption per unit paper product. With the objective of investigating on water saving, EBARA implemented surveys of water balance in two kraft pulp factories within the country on a total factory basis. Based on the results obtained in the above surveys, this article reports the features of water use and the point of effective utilization of water in the kraft pulp factories.


DD Washer in Pulp Washing and Bleaching
Tamio Fukuzawa, Kannji Hagiwara and Masato Tsuchitana
Andritz K.K., Japan
Pekka Tervola and Olavi Pikka
Andritz Oy, Finland

The Drum DisplacerTM-washer (DD washer) has designed in response to the demand for improved washing efficiency, reduced operating, maintenance and capital costs. Today the DD washer is widely accepted by pulp mills all over the world and up till now, about 120 DD washers have been taken into operation.
 The family of DD washers comprises machines that can be fed at low (from 3% to 6%, LCDD) or medium (from 8% to 11%, MCDD) consistency. The number of washing stages varies from one to four. Thanks to its unique segregated counter-current washing principle, a high washing efficiency can be reached. The design and the construction of the DD washer has been further developed, so that even higher displacement washing efficiency can be achieved and this excellent washing efficiency has been proven in the mill trial. The DD washer installation positions include brownstock washing, post-oxygen washing and bleach plant.
 The unique PT Pressure Thickener innovated by Andritz can increase the low pulp consistency by about 2%, thereby improving process water management and washing efficiency of washing devices, for instance, after the screen room. The Andritz Modu screen F is capable of replacing the conventional centri-cleaners in the post-bleach position as has already been done in European pulp and paper mills. The Modu screen F gives high dirt removal efficiency and also provides the special feature of removing light-weighted particles like plastics from the pulp stock. Since the Modu F screen can operate at 3 times higher pulp consistency than the conventional cleaners, it improves water management resulting in energy saving.


System Closure for Kraft Pulp Mill and the Latest Fiberline Technologies
Yan Ju
Kvaerner Pulping KK

 The pulp and paper industry is always under strong pressure from authorities, “green” organizations and consumers to reduce the environmental impact of the pulping processes. Since the dioxin debate, the pulp industry had improved its operation and to reduce the emissions and other substances to the receiving waters with new technologies same as recycling the filtrate or system closure.
 In this paper it will be discussed that system closure for kraft pulp mill and the latest fiberline technologies. At the mention of system closure in kraft pulp manufacturing, it is the important developments include widespread adoption of new cooking techniques, oxygen delignification, closed screening, improved process control, new bleaching methods, and systems that minimize pulping liquor losses.
 It was shown that Kvaerner Pulping new technologies such as the new cooking processes- COMPACT COOKINGTM and KOBUDOMARI cooking systems, a new oxygen delignification system-DUALOXTM, a hot chlorine dioxde bleaching system-DUALDTM, and a new washing equipment-COMPACT PRESSTM are playing an important role in system closure.

Keywords: system closure, Kraft pulp, filtrate, NPE, emission


Modern Bleach Plants- Closure and Bleaching Strategies -
Toru Kobayashi
Metso-SHI Co., Ltd.

A conventional ECF sequence is difficult to close without risk of process problems such as corrosion in the recovery system. With light ECF bleaching including a high consistency ozone stage followed by an alkaline stage without an intermediate washing stage, the water consumption and the COD discharge can be reduced considerably compared with a conventional ECF sequence. The use of ozone in the bleaching has also shown to be efficient to lower the brightness reversion of the bleached pulp. One cause of brightness reversion is hexenuronic acids, HexA, in pulp. Ozone reacts very selectively with HexA and therefore pulps with high HexA content are well suited for bleaching with ozone.


European Aspects of Kraft Pulp Effluents- Current Situation and Future Possibilities-
Christian Blom and Pia Jour
Eka Chemicals AB
Muneo Sakamoto
Nissan-Eka Chemicals Co., Ltd.

The development of Kraft pulp bleaching technology has led to better quality products and lower emission levels. The ECF bleaching technology has become the most common with 75% world market share for bleached chemical pulps (2001). By internal measures (partial closure, spill control, etc) and by external measures (biological effluent treatment) the COD and AOX emissions can be reduced to the level of 10 kg/ADT and 0.2 kg/ADT respectively. ECF bleaching technology is now part of the EU BAT, affecting the current emission limit directives. A massive R & D effort, Ecocyclic Pulp Mill ? KAM, suggests solutions to further reduce the emission levels. However, most of the technologies still await commercialization.

Keywords : Kraft pulp, Bleaching development, ECF bleaching, EU BAT, Emission limits, Partial Closure, Effluent treatment, Ecocyclic Pulp Mill


Adjustable Speed Drive Coupler MagnaDrive−Energy Saving with Non-contacting Permanent Magnetic Coupler−
Mitsuhiko Matsuda
Nomura Shoji Co., Ltd.

Energy saving initiative is very important in any field where energy is consumed. MagnaDrive ASD has been developed in U.S.A. as a variable speed coupler for an electric motor to control rotating speed of load for the purpose of saving electric power to the motor. The MagnaDrive is a magnetic coupler with rare earth magnet, which has most powerful permanent magnetism up to the date. MagnaDrive is to be installed just between axes of motor and load, and requiring neither anymore device nor wiring, and more over is operable under tough circumstances such as in high temperature or at outdoors. In this document, MagnaDrive is introduced with explanation of operating theory, benefits and application examples.