Modeling and simulation of wet-end white water system in the paper mill

A dynamic model representing the wet-end of a paper mill is developed to characterize its dynamic behavior. The model is based on the mass balance relationships written for the simplified wet-end white water network. The dynamic response of the wet-end is influenced both by the white water volume and by the level of wire retention. Effects of key manipulated variables such as the thick stock flow rate, the ash flow rate and the retention aid rate on the major controlled variables are analyzed by numerical simulations. It can be said that the consistency of the model with plant data seems to be reasonably good and can be used as a tool for plant analysis and control.     

Modeling of the drying process in paper plants

In this study a model for the drying process in paper production plants was developed based on the mass and heat balances around drying cycles. Relationships for the heat transfer coefficients between the web and the air as well as between the drying cylinder and the web were extracted from the closed-loop plant operation data. It was found that the heat transfer coefficients could be represented effectively in terms of moisture content, basis weight and reel velocity. The effectiveness of the proposed model was illustrated through numerical simulations. From the comparison with the operation data, the proposed model represents the paper plant being considered with sufficient accuracy.     

Model algorithmic control of grade change operations in paper mills

In this work, the Model Algorithmic Control (MAC) method is applied to control the grade change operations in paper mills. The neural network model for the grade change operations is identified first and the impulse model is extracted from the neural network model. Results of simulations for MAC control of grade change operations are compared with plant operation data. The major contribution of the present work is the application of MAC in the industrial plants based on the identification of neural network models. We can confirm that the proposed MAC method exhibits faster responses and less oscillatory behavior compared to the plant operation data in the grade change operations.     

Preparation of activated carbon from paper mill sludge by KOH-activation

The purpose of this study is the preparation of activated carbon using paper mill sludge collected from biological wastewater treatment plant. The char produced from pyrolysis of paper mill sludge was chemically activated with potassium hydroxide. A systematic investigation of the effect of activation agent ratio, activation temperature and time on the properties of the char was carried out in a rotary kiln reactor. The chemically activated carbons were characterized by measuring iodine and methylene blue number and specific surface area. The activated carbon prepared from char of paper mill sludge in this study had maximum iodine and methylene blue number of 726.0 mg/g and 152.0 mg/g, and specific surface area of 1,002.0 m²/g, respectively. The result of estimation on adsorption capacities of metals, the Freundlich isotherms, yields a fairly good fit to the adsorption data, indicating a monolayer adsorption of metals onto activated carbon prepared from char of paper mill sludge using a potassium hydroxide as the activating agents.     

新型胶体磨的研制与应用

介绍了新型胶体磨的粉碎机理、结构特征及设计要点,并通过工业考核试验,证明了该胶体磨的可行性。     

Possibility of using paper sludge in co-firing applications

The possibility of co-processing paper sludge with coal in power plants for power production and useful products was investigated as an alternative to the disposal option. The thermal behaviour of the fuels and their blend during pyrolysis and combustion processes was studied, kinetic models were developed and the compatibility of each component in the blend was evaluated. The experiments were conducted in a thermogravimetric analysis system, at non-isothermal heating conditions, over the temperature range 25-850 °C. The effect of the inorganic constituents of the fuels and their mixture on thermal conversion characteristics, reactivity, slagging and fouling propensities and environmental pollution was examined.The thermochemical reactivity of the two fuels was different in both nitrogen and air. Devolatilization of paper sludge occurred earlier and with a higher rate, while its combustion was hindered by the high content of ash. When the two fuels were mixed their pyrolysis or combustion reactivities did not substantially change. A first-order parallel reactions model for pyrolysis and a power low model for combustion fitted the experimental results accurately. The kinetic parameters of the blend could be predicted from the data of the individual components. Co-firing paper sludge with subbituminous coal might somehow improve the slagging/fouling potential of the coal. However, if the mineral matter of paper sludge is partly removed before use, then the combustion behaviour of the mixture could resemble that of coal alone and the overall efficiency of the process would increase.     

纸质蜂窝夹芯的粘接技术

按纸质蜂窝夹芯材料的生产过程，较为详细地介绍了它的生产工艺和关键工序应掌握的技术以及各项工艺参数。     

Electrochemical behaviour of methyl viologen in a matrix of paper

Methyl viologen (MV) has been incorporated into paper as an aqueous solution and in the viscous electrolyte polyAMPS, and the availability of the MV for electron-transfer has been investigated by cyclic voltammetry at a stationary platinum disc electrode. In this study, which is the first rigorous study of an electrochrome in paper, the variables of choice were scan rate, relative humidity and electrolyte composition. The implications of the incorporation of MV into paper are discussed in terms of electrochromism. It is concluded that (i) electrochemical generation of colour in the paper is feasible; (ii) the rate of colour formation in paper is likely to be very slow; (iii) the MV²⁺, MV^+· couple is fully electroactive in paper but (iv) the MV^o redox state is best avoided since its immediate product, a spin-paired radical–cation dimer formed via comproportionation, is slightly electro-inactive. Dimer also complicates the electrochemical interpretations.     

Effect of dryer fabric structure on the performance of contact paper drying

Existing measurement techniques have prevented extensive investigations of the effect of dryer fabric structure on contact drying of paper. Using a novel optical measurement method, the moisture content (MC) of paper can be accurately quantified at high spatial and temporal resolution while it is sandwiched between the heater surface and the dryer fabric. To study the paper drying process, an experimental setup is designed to simulate realistic conditions of a typical paper dryer while providing optical access for the measurement system. Ten commercially available fabrics manufactured by weaving synthetic filaments are used in the investigations. The 3D structure of the fabrics is characterized using optical coherence tomography (OCT). The fabrics are used in the experiments to investigate the effects of the filament structure and paper/fabric contact on the drying process. It is shown the fabric structure affects the drying rate and the drying time. Fabrics that have a relatively large drying rate at high paper MC may have a relatively small drying rate at low levels of MC. The contact area and 3D arrangement of the filaments have the greatest impact on the drying process. Adjacent filaments result in larger blocked regions of the paper surface, which reduces the drying rate. The spatial distribution of moisture as a function of time reveals that frequent rewetted spots appear during the drying. These rewetting spots are caused by reabsorption of water condensed on the fabric filaments.     

Fate of methanol in an anaerobic digester

This paper mill was concerned with the anaerobic biodegradability of methanol, its by-products and the potential for gas stripping the system. A series of laboratory-scale experiments were conducted to evaluate the fate of methanol during anaerobic treatment. According to our research result, more than 99% of methanol contained in the condensate was biodegraded during anaerobic digestion. From an anaerobic digester batch test, the second order bio-degradation rate constant,k _b2 , was estimated to range from 3.97×10⁻³ m³/g·day (when only condensate was fed) to 4.06×l0⁻² m³/g·day (when condensate was fed at a proposed rate). The by-products from methanol degradation such as acetaldehyde, and methyl ethyl ketone, were degraded completely in 32 hours. Since the anaerobic treatment process has a retention time of 5 days, condensate by-products are believed to be completely biodegraded. The introduction of condensate into the existing anaerobic pretreatment process appears to improve the treatment efficiency, leading to a more stable anaerobic treatment as well as a reduced sludge generation in the aerobic wastewater treatment process due to the reduced organic loading.     

Investigating the effect of paper properties on color reproduction of digital printing

Digital printing is affected by several parameters including printer and paper type which determine the final printed color gamut and the quality of reproduction. For investigation of those effects, tests were done on the three types of laser printer and six types of paper with different properties of whiteness, roughness, and gloss. The gamut volume was generated by Eye-One spectrophotometer, ProfileMaker, and ColorThink software. Properties of the different types of paper were measured by the atomic force microscopy, spectrophotometer and, goniophotometer. Results showed that the reproducibility was considerably dependent on the type of printer and type of paper. High whiteness and gloss increased the color gamut volume, while high roughness decreased the reproducibility of the printer. Tests on paper properties showed that whiteness had the most significant effect on color gamut volume.     

Mineralogical and morphological changes of calcined paper sludge at different temperatures and retention in furnace

This work reports the project of thermal effects in mineralogy and texture of the paper sludge to employ them as pozzolanic material.For this reason, the chemistry and mineralogical composition has been studied, as well as its morphology by XRD, SEM and EDX.The initial sludge has been treated to 700, 750 and 800 °C during 2 and 5 h being observed that initial kaolinite becomes metakaolinite and that its pozzolanic activity with a paper sludge treated to 700 °C for 2 h is comparable to that of a commercial metakaolinite. The transformation of kaolinite after the dehydroxylation is to convert in amorphous metakaolinite. At the temperature mentioned above, calcite from the initial sludge is maintained active.It is concluded that the pozzolanic activity of metakaolinite is strongly related to the crystallinity of the original kaolinite. Well-ordered kaolinite is transformed into more reactive metakaolinite.     

内循环好氧三相流化床处理造纸中段废水

本实验采用内循环好氧三相流化床处造纸中段废水，经过一段时间的驯化，获得了稳定的出水。CDO去除经保持在65％以上，系统对进水污染负荷的变化具有较大的承受能力。出水Cl^-的浓度有所增加，说明驯化后的微生物可能对有抽氯化物具有一定的降解作用。水气比在1／120至1／140之间可获得最好的COD去除效果。后进行絮凝处理后，出水COD降为60－80mg/L,BODo 50-60/L，色度为100－150CU，挥发性酚的质量浓度小于0．0265mg／L。     

Use of pulp and paper mill residual solids in production of cellucrete

Fibrous residuals generated from pulp and paper mills were included in concrete. Carefully proportioned concrete mixtures containing some of the residuals showed higher compressive and splitting-tensile strengths than concrete without the residuals. Overall, a high correlation was observed between density and strength of concrete containing the residuals. By achieving equivalent density, concrete containing the residuals may be produced equivalent in strength to the concrete without the residuals.     

Grinding time for control of the size fraction of products in the attrition milling

Grinding tests for garnet were carried out by using an attrition mill under wet processes. Effects of feed filling ratios and a chemical agent (sodium hexametaphosphate, SHP) were investigated on the grinding time of the garnet. The progeny particles obtained were screened into various particle size intervals, which were 100 mesh over, 100/400 mesh and 400 mesh under. In order to estimate the mass fraction of the particles in a given particle size interval, mathematical models were derived from the first-order reaction model, then compared to experimental data. It was observed that variation of the feed filling ratio did not show a significant effect on the mass fraction of the product. The chemical agent was, however, effective so that the mass fraction could be controlled by adjusting the content of SHP.     

Technoeconomic analysis of continuous biodrying process in conjunction with gasification process at pulp and paper mills

In the biorefinery context, thermochemical processes have attracted a significant attention in recent years. Such processes generally consist of three main steps: pretreatment, thermochemical treatment, and post-treatment. In these developing processes, drying and feeding of biomass feedstock remain a significant and costly challenge. The moisture content of biomass feedstock must be decreased to an economic level at pretreatment step otherwise it has to have a detrimental effect on the process efficiency and quality of products. This work addresses the drying of biomass feedstock using novel but practical technology, called biodrying. It is a green technology that offers an opportunity for biomass drying without using an external heat source or fossil fuels, since drying energy is generated through exothermic microbial activity in the biomass that enhances the drying rate. This paper focuses on technoeconomic assessment of continuous biodrying technology integrated to gasification-based biorefinery and investigates the conditions that make such novel technology viable in conjunction with gasification process. Fixed capital investment and operating cost of different biodrying scenarios were estimated as M$4.3–21 and M$0.85/y–3.6/y, respectively, and potential benefits (sludge landfilling cost, energy savings, and carbon credit) from integration of the continuous biodrying system in gasification process implemented in pulp and paper mill were calculated, and ultimately economic performances of the scenarios were assessed. Furthermore, the viable biodrying conditions were specified as 4-day residence time and the major viability risk was found to be bound moisture of biomass.     

无壳弹药动力学参数测定

以差示扫描量热法（ＤＳＣ）及热重分析法（ＴＤ及ＤＴＧ）测试了无壳弹药柱的热特性,得到了有关热力学和热分解动力学参数,这对于无壳弹药的配方设计研究具有一定参考价值。     

Synthesis of poly(styrene-co-maleimide) and poly(octadecene-co-maleimide) nanoparticles and their utilization in paper coating

Aqueous polymer dispersions comprising of poly(styrene-co-maleimide) (SMI) or poly(octadecene-co-maleimide) (OMI) nanoparticles were synthesized by thermal imidization of the corresponding maleic anhydride copolymer precursors with ammonia using an organic solvent free process. Different reaction parameters such as temperature, time, agitation speed and stirrer geometry, and molar ratio of ammonia-to-anhydride were investigated in order to find optimal conditions. The obtained copolymer nanoparticles exhibited glass transition temperatures (T_g's) between 140 and 170 °C with particle sizes ranging from 50 to 230 nm. The compositional analysis was conducted by recording ¹H NMR and ATR-FTIR spectra. In addition, SMI dispersions were successfully spray dried and analyzed by SEM. Finally, the polymer dispersion's utility as auxiliary organic pigment in paper coating formulations was evaluated.     

Insight from Atomistic Simulations of Protonation Dynamics at the Nanoscale

In this paper, we give an overview of the role of molecular dynamics (MD) simulations in the field of proton exchange membranes. We focus on structural and dynamical findings regarding the topology of hydrogen bond networks and proton diffusion. On the one hand, findings about water‐containing polymer electrolyte membrane fuel cell materials, such as Nafion and liquid containing pore materials are discussed. On the other hand, proton conduction in water‐free systems is elucidated. Here, the focus lies on phosphonic acids, which possess a rigid structure, and polymers based on phosphonic acids.     

The use of natural essential oils as antimicrobial solutions in paper packaging. Part II

We have assessed the antimicrobial, vapor-phase activity of the following natural essential oils (EOs) when used in paraffin-based “active coatings” for paper packaging materials intended to come into contact with foods: clove (Sygzium aromaticum), cinnamon (Cinnamomum zeylanicum), and oregano (Origanum vulgare) EOs, and cinnamaldehyde-enriched cinnamon EO. To our knowledge, this is the first time that such an approach has been presented for consideration by the scientific community.