For the final concentration of the black liquor a special system have been developed, the so-called “REVAP” vapour recycling system. This system is especially beneficial when evaporating black liquor to high solids as it improves the heat transfer rate.
Black liquor of high dry solids have a high viscosity, which affects the heat transfer in evaporators. With “REVAP” vapour recycling there is a possibility to improve the heat transfer in falling film evaporators. “REVAP” vapour recycling is a system where a vapour flow shears the falling liquor film, and thereby the heat transfer coefficient of the film is improved.

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In Europe, ozone generators have been modified from the air feed system to the oxygen feed system and begum to be applied in water works or for pulp bleaching.
In case of oxygen feed, the equipment is simplified, the concentration of ozone product is raised five times, and the running cost is reduced.
In Japan, too, it is time for initiating the discussion of application of the ozone generator by oxygen feed.

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In June 1993 ten (10) volatile organic compounds (VOC) were added to the list of the restricted factory exhaust gases as sources of odor under Japanese law. Japanese industry has stricter VOC pollution controls than ever before.
The regenerative thermal oxidizer (RTO) was not commonly used in Japan although it has been widely accepted in the United States and Europe.
Last year we received a technological license from Ross Air Systems, Inc., USA and contracted for two (2) RTOs in the Japanese market.
Through our experience we would like to introduce the features and method of operation of RTO.

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In order to decrease heat consumption and to increase the capacity especially in modernizations, Ahlstrom has designed LMD (Lime Mud Dryer) system and Sector cooler. LMD system and Sector cooler have simple and strong construction. To prevent plugging problem, Ahlstrom eliminated a crusher and high inside circulations from the feed end of lime kiln.

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Though the foul smelling sulfur compounds in pulp drainage (hydrogen sulfide, methyl mercaptan, methyl sulfide and dimethyl disulfide) have been usually deodorized by the air-or steam- stripping method, methyl sulfide and dimethyl disulfide are liable to remain in the effluents.
In this study, we examined the alternative chemical method using chemicals which react with the sulfur containing compounds and noticed that iron/hydrogen peroxide system is effective for removing not only hydrogen sulfide and methyl mercaptan but also methyl sulfide and dimethyl disulfide.
We found, furthermore, that a vanadium compound enhanced remarkably the performance of this system.

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In the paper coating field, synthetic water retention aid has been recognized as to improve productivity and total quality of coated paper, and its usage is gradually expanding. We are studying and developing new water retention and rheology modifiers which are effective for these improvement.
In this paper, I would like to show the general summary of water retention and rheology modifier in paper coating field, and test results of our product “SN-Thickner 922”. The coating color containing “SN-Thickner 922” has higher water retention and lower high shear viscosity rather than control so that it is suitable for high solids coating and high speed coating which are present technical trends for the improvement of productivity.
“SN-Thickener 922” can also improve paper qualities such as gloss, inkset and trapping compared to CMC or starch

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The relationship of coating micropore, optical properties and print mottle were studied. Coated papers with various micropore size distribution were prepared on a pilot SDTA coater and were printed on a 4 color sheet-fed offset press. The print mottle was evaluated both visually and with an image analyzer. The micropore of the coating, unevenness of the coating and optical properties of the coated paper such as whiteness were measured. Then the relationship between print mottle and these measured factors was studied.
The results are summarized as follows ;
(1) There is no mutal relationship between print mottle and micropore of coating.
(2) Uneven whiteness of non-printed areas affects the print mottle. Sometimes it increases print mottle and sometimes it decreases print mottle.
(3) Such uneven whiteness is caused by uneven opacity of the paper.

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We have developed a new air permeability tester with which we can measure the acceleration of the air permeability of coated paper under high temperatures (300°C) and pressure (4.00 kgf/cm²) during a short time. These conditions are close to the real world in the drying process of web-offset printing press. The acceleration of the air permeability is thought to be an ability in the coating layer to respond to rising water vapor pressure in a short time during the drying process of web-offset printing press.
With the new air permeability tester, the correlation between the acceleration of the air permeability and the blistering resistance of various coated papers was investigated. These coated papers were prepared with different binders, amounts of binders, pigment formulations and binder contents in each coating layer.
We found that the acceleration of the air permeability was more strongly related to the blistering tendency of coated papers, than conventional air permeability testers. So, the result indicates that the new air permeability tester is very useful in predicting the blistering tendency of coated paper.

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Polyvinylamine can be synthesized by polymerizing vinylformamide and then hydrolyzing it. This results in a chain type macromolecule with primary amino groups only, and without remainder monomers. When then molecular weight is sufficiently large and the charge density reduced excellent retention and drainage aids are obtained, with relatively little tendency to flocculate. Highly charged polymerates of medium molecular length make very good fixatives for contaminants, rosin and colourants, and they work well as dry and wet strengthening agents under neutral conditions.
Such synthesis method, application and properties of polyvinylformamide and polyvinylamine are introduced and discussed.

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Recently UV curable resins are being used in a wide range of industrial fields. In pulps and papers industry field, progress has been forthcoming in surface coating of paper for carton or jacket. We thought recyclic property of UV curable resins is very important to develop the recyclable surface coating paper using these resins. This report describes the approach to develop the UV curable resins for recycle surface coating paper using these resins.

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For the diversification of paper products and the productivity improvement of paper manufacturing, new quality of surface modifiers are being demanded. Moreover, recent trend of environment protection demand the modifiers another quality.
In this article, We introduce our surface modifiers which are newly developed and able to satisfy many sorts of recent demands. POLYMERSET HP relies, a new line of polyacrylamide-based resin with high solid content, are generate excellent surface strength of parer. Surface sizing agent POLYMARON 1343 S can be applied for the Ink-Jet parer and exhibit remarkable quality to prevent ink penetration into paper. TAMACOAT GN-40 has ability to decrease the adhesivity of paper in wet state which is caused by starch and PVA.

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In recent years, ink-jet printing has grown dramatically in popularity for used with personal computing systems at home as well as in offices. Moreover, full color ink-jet printing may hold a dominant to monochrome ink printing.
Common usable paper for monochrome ink jet and electrophotographic printing has already come into the market. Exclusive papers are applied for full color ink-jet printing to maintain sufficient ink penetration rates and water resistance without color bleed.
Our newly developed CJ-1100 improves in full color ink-jet printability performance such as excellent water resistance and higher optical density for plain paper.

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Recovery and recycle of white water in papermaking process is important for the reduction of waste water and conservation of energy.
Generally, coagulation sedimentation or flotation treatment is applied as the primary treatment to white water. Next, filter media filtration is applied as the secondary treatment.
The following two points are most important for successful treatment of white water.
(1) Suspended solid concentration of the primary treated water needs to be maintained below 20 mg/l.
(2) Slime control of white water recovery line needs to be done thoroughly.

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Recently, application of G·R·C are expanding in accordance with requirements of the time.
Abrasion at both ends of chrome plated surface for metering roll has been seen, since early stage of G·R·C.
We thought that, some components of coated solution, which are running with transition by customer needs, have sometimes caused corrosion at surface of chrome plating. Above mentioned two troubles are now most nportant news for Paper Machin Industry.
As a result of investigation with charge about distribution to metering roll surface, abrasion at both ends of metering roll are caused by straight (no-crown) surface, we recogniged.
We had understood that, insufficient closely contact between applicator roll and metering roll, disturb normal lubicant of coated color, and make corrosion at chrome plated surface.
So, metering roll with micro camber for roll crownning, improves accuracy of contact pressure distribution and abrasion form at both ends.
Moreover, as for edge abrasion, application of thermal sprayed coating will counter measure to meet prolong its service life, we judgment.

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Because the quality requirement of converting field is becoming diversifying, pulp and paper industries began to ask their inspection system for new function which is to detect light contamination and fine streaks other than existing spot type defects such as black specks, pinholes, etc.
In order to answer such a requirement, we introduce new inspection system which you can apply for.

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Recently, to increase the quality of paper, high temperature calendering by using induction heated rolls with heat pipes is attracting a great deal of attention, because of high temperature capability and temperature uniformity across the roll.

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Neutral rosin sizing agents are presently produced with rosin esters used as a main component and anionic synthetic polymers as an emulsifier. In sizing containing calcium carbonate, such a sizing agent produces a sizing effect with aluminum sulfate (alum) used in a pH range of 7-8.
Here, the new neutral sizing agent (NE-HP) will be introduced which develops a sizing effect without the aid of alum even when a high concentration of calcium carbonate is employed.
The features of this sizing agent will be shown through measurement by visible region spectrophotometry of the quantity of the sizing agent separating from pulp with an agitation shock or pH change in sizing.

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We developed polyacrylamides (PAMs) with high concentration and high molecular weight.
In this paper the relationship between solution properties of those PAMs and its paper strength performances was tried to make clear.
Especially molecular size of PAM that thought important was measured by new types of analytical apparatus.
HOPELON 740 and SANTAX 30 series were paper strength resins that developed by those analytical methods.

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In recent years, the shortage of land for industrial waste disposal has been a problem and it has become a social demand to reduce excess sludge generated in the waste water treatment process based on aerobic biological treatment. In compliance with this social demand, our company developed a technology for reducing excess sludge by two-stage treatment consisting of aerobic biofilm and activated sludge process.
This new technology not only reduce excess sludge but also enables simplification of operation control attributing to improvement in the sludge properties.

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Studies were made using peroxide-based bleach chemicals, silicomolybdate-activated peroxide (mP), peracids and combinations of them in the delignification process of kraft and sulphite pulps. The results demonstrate that these chemicals are suitable for delignification of elemental chlorine-free (ECF) and totally chlorine-free (TCF) Pulps.

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It is known that shape characteristic of fiber has influence on physical property of pulp and paper. However there was no proper means to measure the shape of fiber up to now and took a lot of time and work to measure it with conventional means.
Now we would like to introduce an automatic measuring instrument to measure length and shape of each fiber, called “Fiber Quality Analyzer” developed in cooperation of 3 parties namely OpTest Equipment Inc./Canada, Pulp and Paper Research Institute of Canada, and The University of British Columbia.

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The digital friction instrument is originally designed to measure the static and kinetic friction coefficient of paper, but also availobe for such materials as film plosties etc.

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MCA's representative in-line measurement occurs between two sensor heads in the process line. The measurement is based on the knowledge of the process medium's dielectric properties. Such mediums in pulp sock include water and solid matter. whose dielectric constants are different. In technical terms the measurement is carried out by measuring the time of propagation as microwaves pass through the stock.
Thanks to its measurement principle, MCA is insensitive to process-induced turbulence. Common process variables, such as flow rate or pressure, do not affect the reliability of the results within the application range. Nor, do application specefic factors-freeness, fiber length, brightness, and color-affect the measurement.
MCA is linear relative to consistency. A single point calibration is enough to tune the MCA to measure with a repeatability of ±0.01% Cs.

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We have initiated a variety of laboratory studies to assess the environmental impacts of pulp and paper mill effluents in Japan. Here we present the outline of lethal and sublethal short-term toxicity tests employed for the assessment and some results obtained by testing 17 whole mill effluents.

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