2007年5月 紙パ技協誌

[プリント用ページ]
Energy Saving by Remodeling the Existing Boiler to the Gas Firing

Kazuaki Shimizu
Hokuetsu Paper Mills, Ltd.

 In the Nagaoka Mill of Hokuetsu Paper Mills, Ltd. we have maintained the mill, considering environmental protection (reducing CO2 etc.) and energy-saving. Under the recent sudden rise in prices of oil, further improvement in environmental protection, energy-saving and reduction of energy costs has come to be urgent. We determined to adapt our heavy oil boiler plant for natural gas that is supposed to be the most effective way to solve the above problems. The remodeling of all our existing boiler plants finished in November last year. In this report, we introduce the point and the effect of the remodeling.


Black Liquor Evaporation to High Dry Solids with Crystallization Technology

Heikki Jaakola
Evaporator Technology, Andritz Oy
Tetsuo Hatano
Evaporation Technology, Andritz KK

 Modern pulp mills have improved their energy efficiency by increasing firing liquor dry solids concentrations. Steam production in a recovery boiler can be increased over 2% when the firing liquor dry solids content is increased from 75% to 80% /1/. At the same time also SO2 emissions are practically eliminated.
 When black liquor is evaporated to concentrations over 50-55% sodium salts start to precipitate from the liquor. The precipitated salts form crystals in the liquor and more or less scale on the evaporator heating surfaces. Traditionally the scale is removed from the surfaces by sequence switching technique, which may require water washing even daily.
 The scaling formation on the heating surfaces can be reduced remarkably by mixing electro static precipitator ash in the liquor before high dry solids concentration. The ash particles act as centers of crystallization (seeds / nuclei). The crystallization takes place on the ash particles, not on the heating surfaces and the need for the washings will be reduced remarkably.
 This paper describes Andritz’s concept for high dry solids evaporation with crystallization technology.


Steam Saving by Waste-Heat Recovery from Pulping Wastewater

Susumu Chiba
Hachinohe Mill, Mitsubishi Paper Mills Limited

 In Hachinohe mill of Mitsubishi Paper Mills Limited, an energy saving is forwarded as an urgent task for a cost-reduction theme which is set in "Pheonix Plan" of our company. An energy-utilization committee and an executive meeting of international organization for standardization (ISO) 14001 in our mill are organized with same members to link efforts for the task. Thus, we are tackling an improvement of a specific energy-consumption grasping an effect of the energy saving in real time.
 In this paper, effects of facilities, which started running in November 2006 for a waste-heat recovery from wastewater, on the energy saving were described. These efforts were conducted for saving an increased steam usage in a papermaking process by decreased water temperature in winter. Water temperature was increased in the papermaking process by recovering waste-heat which had been discharged to the atmosphere from a cooling tower of pulping wastewater. This considerably improved a specific steam-consumption in the process.


Energy Saving Cases in Kraft Pulping Section

Hidemori Ninomiya
Pulping Section in Sendai Mill, Chuetsu Pulp & Paper Co., Ltd.

 Recently, there has been an urgent need to reduce the cost in pulp and paper mills, since the cost of raw materials and fuels such as raw wood and crude petroleum has risen. Energy consumption in pulping section is high, then it leads to high production cost.
 Its reduction even a little could contributes to company’s profits.
 In this article, energy conservation which has been achieved by optimizing the use of warm water, filtrate and operating condition in the bleaching process, is reported.


Steam Turbine New Sealing and Clearance-controlling Technologies

Nobuhiro Osaki
Power Plant Service Center Power Systems Headquarters,
MITSUBISHI HEAVY INDUSTRIES, LTD.

 In order to reply the recent growing needs for energy saving, we focused the steam leak which is one of the most affective to degradation of efficiency and developed and applied for new technology to reduce leak loss.
 Leaf seal is a new type of seal. It is different type from conventional labyrinth seal. It has superior feature of good sealing and avoidance of the heat by contact to the rotor. ACC (Active Clearance Control) seal can change the clearance between during start & stop and during load operation. It prevents contact during start & stop and keeps smaller clearance in order to gain efficiency during load operation. Cooling cell prevents contact between lower half of the casing and the rotor by decreasing the differential temperature between upper and lower half casing.
 First we applied these new technologies to our in-house power plant for verification. After confirmation of performance and reliability for these new technologies, we applied them to commercial unit without any problems.
 We introduce these new sealing and clearance-controlling technologies.


Reduction of Heavy Oil Consumption in Lime Kiln

Ryo Konishi
Oji Engineering Co., Ltd., Kushiro Dept.

 Kushiro Mill produces 700 thousand tons per year of newsprint, coated paper, mechanical paper and linerboard by four machines with pulp plants (KP, RGP, DIP and OCC). Based on The Oji Paper Group’s Environmental Charter, Kushiro mill has positively used recycled resources for Product design and process of manufacture with small environmental burden. Because of the increase in the wastepaper utilization rate, Kraft pulp and The Black liquor production decrease every year.
 The Black liquor from KP plant is used Recovery Boiler for recollection of heat and White liquor, so it is important to reduce the energy cost in the mill.
Since the Black liquor has decreased, a process that produces White liquor and Lime must been operated minimum rate.
 In this report, I describe efficiency improvement of Lime Kiln to reduce Heavy Oil consumption.


Saving Fuel Oil by Capacity Increase of No.4 Boiler

Tatsuya Kamada
Nippon Daishowa Paperboard Tohoku Corporation

 In accordance with our environmental policy; "Resources & Energy Saving" and "Reducing & Recycling of Waste", we constructed a Waste Heat Power Generation Plant (named No.4 Boiler) and started commercial operation of the plant on October 2003.
 The Plant runs on Paper Sludge and Waste Tire without auxiliary fuel (i.e. fossil fuel) and generates high temperatures and pressures steam stably with Waste Heat Boiler and generates 14,000 kW.
 We have achieved certain reducing of fossil fuel consumption, and we improved the plant for further resources saving. We increased the steam generation capacity from 65 ton/h to 73 ton/h by adding biomass fuel (i.e. wood chip) to cut tire and paper sludge. And we started operation of the plant on February 2005. We successfully could reduce the fuel consumption of No.2 Boiler by supplying the increased steam of No.4 Boiler through the new process piping.
 Now we will present an overview of construction work and operation experience of the plant.


Case Studies of Collecting Our Waste-Heat at Mishima Mill, Daio Paper Corporation

Taku Fujita
Mishima Mill, Daio Paper Corporation

 The power generating facility at Misihima Mill has a 531 MW standard output and consists of 18 boilers and 14 turbines. It supplies all the electricity used by the facility and its surplus electricity output is sold to the market.
 After the oil crises of the 1970’s, Daio Paper shifted from a dependence on petroleum towards coal. Since 1985 we have also attempted to increase energy production efficiency in the power plant by raising the pressure and the temperature in the boilers and installing new turbines. Additionally increased our production of recycled pulp in the production process because it requires less energy than wood chip processing. In 2005, we accomplished a 17% reduction in fossil fuel energy consumption based on tonnage of output compared to 1990.
 We are trying to accomplish a 23% reduction by 2010 compared with 1990 levels in fossil fuel energy consumption based on tonnage of output, a 20% reduction in carbon dioxide consumption.
 Case studies of our energy curtailment efforts at Mishima Mill are discussed in the following section


Power Consumption Reduction by Modifying Oil-outlet and Pressurizing Shoe of CCR

Katsuyuki Fukushima
Facility Department of Maintenance Section, Tomioka Mill, Oji Paper Co., Ltd.

 CCR (Controlled Crown Roll) is one of important equipments to get even dewatering in the cross machine direction.
 It was developed jointly by Mitsubishi Heavy Industries, Ltd. and Beloit Corp. over thirty years ago. And many CCRs are still in operation. But paper machine speeds has been increased 1.5 times compared with the original design by a lot of rebuilds. Therefore, many problems recently happen.
 We will introduce some trouble cases maintenance engineers faces on and solutions. And also, an example of save energy by modifications of CCR on second press in Tomioka PM9 will be introduced, too.


Role and Effect of Ionic Groups of Polymer as a Surface Sizing Agent

Takahiro Fujiwara
Paper Chemicals Division, Harima Chemicals, Inc.

 In this paper, sizing behaviors of synthetic water-soluble polymer surface sizing agents with different ionic charges were investigated using bleached kraft pulp base papers prepared in various conditions. The sizing efficiency of anionic surface sizing agent (A-SFS) was proportional to the alum content in the base paper, and the addition of CaCO3 to the base paper reduced its effect apparently. On the other hand, it was found that the sizing behavior of cationic surface sizing agent (C-SFS) depended on the presence of CaCO3. While the sizing efficiency of C-SFS rose with the increase of alum content in the base paper without CaCO3, that of C-SFS tended to drop with the increase of alum content in the base paper with the addition of either 10 or 20% CaCO3.
 These results indicate that C-SFS develops surface sizing on papers with more complicated mechanism than the case of A-SFS. Furthermore, we suggest a novel mechanism of surface sizing by using various analytical techniques as well.


Estimation of the Cost of Afforestation by the Cost Analysis

Tokiya Yaguchi, Takayuki Sato, Masato Takagi and Shigehiro Okamura
Research Planning Group
Research Institute of Innovative Technology for the Earth

 In order to calculate the cost of carbon dioxide fixation by the large scale afforestation (AF) for the reduction of the global greenhouse gas, we have analyzed in detail about the one model AF data and 4 publication AF data. In this report, we have defined the unit cost of accumulated (Acc) AF cost by US$/ha/year as below.
 The unit cost of Acc AF cost by US$/ha/year
 = The Acc AF cost by US$/the Acc area of AF by ha/year
 As a result, we have obtained an estimated (Est.) cost of AF by US$/ha/year with the functional formulas of the AF year (n) and the gross domestic product per capita (GDP/cap) of the AF country.
 Est. cost of AF by US$/ha/year = 130 + 0.0341×n-0.445×GDP/cap (20≦n≦30)
There is a significant coefficient (R2 = 0.88) in 44 data between the real Acc total cost of AF and the est. value.
 By the same token, we have obtained Est. Cost of AF by US$/ha/year among 3 to 30 years of AF.
 Est. Cost of AF by US$/ha/year = 800×n-0.566 + 0.141×n-0.879×GDP/cap (3≦n≦30)
In this case, there is a nearly equal coefficient (R2 = 0.90) in 157 data between the real Acc. Total Cost of AF and the Est. Cost of AF.

Keywords: cost of afforestation, estimation, cost analysis, afforestation years, gross domestic
       product per capita


A Report on the 20th ISO/TC6 Meeting

Takayuki Okayama*1, Takashi Yaezawa*2, Shisei Goto*3 and Tadashi Kano*4
*1 Tokyo University of Agriculture and Technology
*2 Oji Paper Co., Ltd.
*3 Nippon Paper Industries Co., Ltd.
*4 Japan Technical Association of the Pulp and Paper Industry

 ISO/TC6 meeting was held on November 13-17, 2006 in Atlanta, USA. The number of registered delegates representing seventeen countries was seventy three.
 Four delegates representing Japan attended WG meetings, plenary meetings of SC2 and SC5, and TC6 plenary meeting.


Development of Method for Analyzing Internal Properties of Coated Paper: Image Analysis Using X-ray Microtomography

Yusuke Kondo
Nippon Paper Industries Co., Ltd.
Cyrus K. Aidun
G. W. Woodruff School of Mechanical Engineering
Georgia Institute of Technology

 This paper reports a technique, based on analysis of X-ray micro-tomography images to analyze the internal properties of coated paper through the thickness direction (ZD). The image analysis method for paper applications using μCT have been developed by a few groups, but the method that can analyze these images to obtain the full range of properties in detail has not been presented before.
 The internal properties include formation and fiber orientation distribution through the thickness direction (ZD), as well as ash and pore distribution in x-y- and z-directions. The image analysis technique involved many steps including axial conversion, filtering, binarization, skeletonization and alignment. The method is applied for analysis of two kinds of coated paper and the results provide interesting insight for papermaking.

Keywords: X-ray tomography, ash, formation, fiber orientation, distribution, image analysis,
       Z-direction, pore