2004年6月 紙パ技協誌

 

JAPAN TAPPI JOURNALVol. 58, No.6

June 2004    Abstracts


Heat Recovery from the Waste Water
Hiroyuki Watanabe
Kushiro mill, Oji Paper Co., Ltd., Oji Engineering Kushiro Dept.

 Kushiro Mill produces 700 thousand tons per year of newsprint, coated paper, mechanical "paper and linerboard by four paper machines with pulp plants (KP, RGP, DIP and OCC). In compliance with social requirements on environmental protection, Kushiro mill works for the increase in the wastepaper (DIP) utilization rate, according to environmental of Oji paper. And the expansion of DIP plant was completed in 2003.
 As known, large quantities of warm water is necessary with DIP production process for washing of the ink particles which deinked from the wastepaper. The location of our mill is the cold districts, so it is necessary to use many amounts of steam at the pulp and the paper machine process.
 We had to make warm water by using a new source of heat, because the warm water from the condencing turbine and machine waste heat was already consumed in the mill. In this report, I describe the Heat Recovery from the new source which is waste water, and the saving energy.


Improvement Example to Reduce Water Content of Paper Sludge
T. Hosaka, T. Kato and K. Kobayashi
Kushiro Mill, Nippon Paper Industries Co., Ltd.
 
 We have worked the sludge boiler that utilizes the paper sludge (PS) as the main fuel in 1992.And we are advancing the application of the renewable energy that is substituted to fossil energy.
 In recent years, with advancement of the waste paper utilization, the materials for the paper making of our mill changed the de-inked pulp from the mechanical pulp. Also the amount of PS increased with utilization of DIP, the ratio of PS in the sludge boiler reached the point of approximately 70%.
 On the one hand, the ash of mill draining rises due to the utilization of the magazine waste paper, accordingly energy efficiency of the sludge boiler deteriorates.
 This time, we assured equipment remodeling and PS-fluke stabilization in PS dehydration process. As a result, PS percentage of water content decreased, as for us, could improve PS combustion energy.


Energy Saving by Adopting the High Efficiency Steam Turbine
Kenji Okamoto and Toshiaki Hatakeyama
Saga Mill, Oji Paperboard Co., Ltd.

 The Saga mill No.2 steam turbine of our company has operated for 34 years and totally 12.0% efficiency decline at maximum output operation have been recognized which consists of deterioration in the turbine, pressure loss at the reconstructed extraction point and etc.
 By replacing the turbine rotor, diaphragm and nozzle to the high efficiency type which causes 14.85% efficiency improvement at maximum output operation and by shifting the operation mode from the condensing power generation and purchasing power to the extracting power generation, we have achieved both energy saving and cost cut.


Energy Saving with Atmospheric Steam Reduction
Shinnei Furuse
Yatsushiro Mill, Nippon Paper Industries Co., Ltd.

 At yatsushiro mill, coal fired power plant has been operated successfully since 1993and it contributes to the cost reduction of Yatsushiro mill.
 In early 1998, installation of the world-class N2 newsprint machine was completed, adding, substantially to our international competitiveness as a paper mill.
 N 2 newsprint machine produces a haif of total production of Yatsushiro mill. On that account, when N2 paper machine stopped, we would stabilize boiler load with the releasing of atmospheric steam to decrease a large amount of the boiler load.
Power plant operators in a small group activity made a study of the stop timing of a coal mill.
 In this report, we describe the results of a small group activity successful to archive the reducing of the atmospheric steam by a large marginies.


Activities of Energy Subcommittee at Niigata Mill, Hokuetsu Paper Mills, LTD.
Tomoo Arano
Hokuetsu Paper Mills, LTD., Niigata Mill Technical Section

 The annual consumption of Hokuetsu paper Mills, LTD. Niigata Mill is approximately 5,000kL per year, converted into heavy oil. The activity of main energy saving has been started up since 1980 and now operating division, engineering division, and administrating division cooperate in the energy saving by means of the Energy Save Meeting. The target of the energy saving is 1% reduction of the annual energy consumption for purchase. The energy saving result in last three years was 9,200kL, and attained to the target. According to the classification of the energy saving by pattern, 75% of the energy saving case are easily case that stop surplus instruments by improvement the operating standard or changing flow. The recent main energy saving case in Niigata Mill are changing impellers of medium consistency pumps and examinations applying temporarily inverter unit for the preset motors.


The Examples of Energy-Saving in Oji Kure
Shoji Hirooka
Oji Engineering Co., Ltd., Kure Mill

 Oji Paper has set itself the target of reducing its purchases of energy in unit terms by 2010 by 10% compared with 1990, and promoting activity in the whole company. Since 2000 when Oji Kure mill obtained environment control international standard (ISO 14001)certification, we are performing energy-saving activities in the program of the environmental management system (EMS). 
 I introduce some examples characteristic as a pulp-paper mill, and the situation in the Kure mill from the latest energy-saving result.


The Improvement in an Energy Original Unit and the Energy-Saving Example in a Futatuka Factory-Transition and Consideration of Energy and CO2 Original Unit-
Masashi Masui
Futatuka factory, Chuetsu Pulp & Paper Co., Ltd.

 Chuetsu Pulp Futatuka Mill is in Takaoka-City of Toyama-Pref., which is located in the middle of Kanto economic region and Kansai economic region, supplies the products to the customers in both Tokyo and local area. The mill produces 180,000t/y of newsprints mainly.
 This time, the main theme of Energy-Savings Seminar is “Returning to the starting point : an example of energy saving of the mill”, and our theme is “Transition of energy consumption per unit and Example of energy-saving” concerning about the change of fossil fuel consumption per unit from 1990 to 2002.
 According to the data book 2003 investigated by Japan Technical Association of Pulp and Paper Industry, both the purchase energy and CO2 consumption per unit of Futatuka mill has been descending from the peak of 1993. Of course it depends on the increase of production simply judging from the index of production level, although, it is considered that the implementation of energy saving and the improvement of efficiency has contributed mostly. I try to make the important factor clear with adding consideration, and also the following is a successful example of energy saving implemented.


The Recent Activity of Energy Conservation at the Kasugai Mill
Junichi Nakamura
Kasugai mill, Oji Paper Co., Ltd.

 Ojipaper Co., Ltd.’s Kasugai mill started operating in 1952. Recently the mill demands an ever increasing amount of electricity and steam. This is caused by greater production of used paper products; use of ECF sequencing in bleaching wood pulp; and increased electricity demands if new high-technology machinery. In this paper the composition, usage and conservation of energy in the Kasugai mill are reported.
 We classified the energy conservation activity, which was carried out from1998 to 2002 (fiscal years), into 10 main themes and 6 sub-themes. Each amount of energy conservation was converted to the crude-oil equivalent. It turns out that conservation of about 7000 KLs and22,900 CO2 tons has been attained by the end of 2002. The energy conservation effect is large and furthermore we’re going to introduce seven examples whose technique could be applied to elsewhere.
 Furthermore, in order to attain the independence action plan of the paper and pulp industry titled; "Cutting down a purchase energy field unit ratio per product for 10% compared to 1990, by 2010”, we set up the numerical target which should be attained by the end of the 2008 fiscal year.


Energy Curtailment at Mishima Mill, Daio Paper
Masanori Watarikawa
Mishima Mill, Daio Paper Co., Ltd.

 The power generating facility at Mishima Mill has a 531 MW standard output and consists of 18 power boilers and 14 turbines. It supplies all the electricity used here and the surplus electricity is sold to the market.
 After the oil crises Daio Paper shifted fuel dependence from heavy oil toward coal. Since 1985 we have also attempted to be more efficient in the power plant by raising the pressure and the temperature in the boilers and installing new turbines, and increased production of recycled pulp which has a low energy consumption rate.
 In 2002, we accomplished a 15% reduction in fossil fuel energy consumption/paper tonnage compared to 1990.
 However, facing the reality where reduction in carbon dioxide emission is required to meet the demands of global warming prevention, we are making independent efforts in the area of energy curtailment and fuel, with the aim of more than a 10% reduction by 2010 compared with 1990 level.
 Energy curtailment cases in Mishima Mill are discussed in the following section.


BTF Dilution Headbox System- Comparison Data between before and after BTF Retrofit -
Junichi Yano
Design Section, Kawanoe Zoki CO., Ltd.

 We will give a presentation on how much product quality can be expected to improve by retrofitting the BTF system to an existing headbox, based on machine startup data in the USA and Canada.
 Since many roll type headboxs are still in operation in Japan, we will also introduce data of two kinds of roll type headboxes this time.
 The first system in Japan started up in July this year. We are sure we will be able to talk about an interesting result of installation in the near future.


Developments for High-Speed, High-Efficiency &Stable Paper Coating
Masahiro Sugihara
Mitsubishi Heavy Industries, LTD., Hiroshima R&D Center
Hiroshi Miura
Mitsubishi Heavy Industries, LTD., Paper & Printing Machinery Division

 Mitsubishi Pilot Coater has been rebuilt to improve high-speed coating performance and to realize the simultaneous both side film coating. This rebuild enables our new developments for high- speed, high-efficiency and stable coating technology and customer's coating trials for verifying the performance of coater or coating color composition.
 The efficiency of the state of the art "MJ-Sizer" for misting reduction and web stabilization, and the novel "Ejector & Steam substitution System" for high-speed free jet type applicator for prevention of air entrainment at the interface between coating color jet and base paper surface, have been verified by using this high-speed pilot coater. Several fundamental studies on film coating, blade coating and curtain coating are also being carried out to realize the high-speed, high-efficiency and stable coating operation.
 In this report, we present our new high-speed pilot coater and some new technologies for high-speed coating.


Technical Trend of Mechanical Seals for Pulp & Paper Plants−Mechanical Seal Technology meeting Environmental Preservation−
Hidekazu Takahashi
Eagle Industry Co. Ltd., Seal Engineering Dept.

 A mechanical seal prevents or reduces outboard leakage of toxic chemicals and saves energy and resources. Therefore, it can be deemed as one of the important environmental instruments that is directly and indirectly contributing environmental preservation. In a pulp & paper plant, many numbers of varieties of pumps are utilized such as water pumps, pulp pumps and chemical pumps all through the production processes from digesting to painting. In recent years, a mechanical seal has been selected as a standard sealing device for such pumps to pursue economical advantages by save energy, save resource and save maintenance points of view and is greatly contributing environmental preservation. I will make brief explanation of the mechanical seals first and then show you examples of environmental issues and contributions achieved by the mechanical seals.


Improvement of Hardwood Pulp Yield in Continuous Kraft Cooking and Estimation of Pulp Yields (Part I)−Optimal Conditions for Yield Increase and Estimation Using Carbohydrate Analysis−
Tomoya Yokoyama and Hiroshi Ohi
Institute of Agricultural and Forest Engineering, University of Tsukuba
Keiichi Nakamata
Technical and Development Division, Hokuetsu Paper Mills, Ltd.

 The optimal conditions of isothermal cooking (ITC) for yield improvement of hardwood kraft pulp were established using Acacia mearnsii wood in a laboratory. The addition of both 1% sulfur and 0.04% soluble anthraquinone on wood gave an about 4.5-5% higher pulp yield at a kappa number of about 17. The highest yield was obtained when 70% of total active alkali and 100% of both PS and AQ were added at the beginning, and successively, black liquor was exchanged with fresh white liquor containing the remaining 30% of total active alkali just after the cooking temperature reached 135°C. A linear correlation was observed between pulp yields and ratios of xylose to glucose (X/G ratios), liberated from the pulps by an acid hydrolysis. This result means that a pulp yield can be estimated by knowing an X/G ratio of the pulp. However, it was indicated that the linear correlation for Acacia mearnsii can not be applied to cooking of different wood species.

Keywords: kraft cooking, isothermal cooking, polysulfide, anthraquinone, carbohydrate, pulp yield