Tissue Paper Mill Research Articles

Waste management in a tissue paper mill: a practical approach

The principles of sustainability, together with the Sustainable Development Goals (SDGs) defined by the United Nations (UN), are essential tools for achieving and maintaining quality of life for the coming years. The sector can make use of these objectives, and the process can become more efficient, with less water consumption and reduced waste. Using virgin cellulose fiber derived from eucalyptus or even recyclable white paper as raw material, this production method is responsible for producing paper with characteristics such as softness, low grammage and good liquid absorption, with products such as toilet paper, napkin, among others. Within the manufacturing process, several procedures can be responsible for the appearance of lint and paper dust, being a type of waste in this industry. Among these, we can mention the increase in fines content, resulting from the fiber refining process, initial mechanical treatment of the paper raw material, which provides the product with resistance. The paper crepe formation procedure is responsible for making the tissue sheet acquire characteristics such as softness and volume, but which can lead to the creation of waste. Through a simple approach related to the balance of process materials, with the analysis of process inputs and outputs, the aim of this work is to estimate the amount of material lost in a tissue paper machine. It is a fundamental preliminary assessment for making decisions regarding waste management.

Robust optimization and data-driven modeling of tissue paper packing considering cargo deformation

This paper considers the container loading problem (CLP) for efficient packing of low density tissue paper products, for which, volume, instead of weight, is the key driver for logistic decision-making. Tissue products are susceptible to deformation during the packing process. However, this aspect is usually overlooked when defining the optimal packing policy. In this work, we take this aspect into account and develop a novel methodology for CLP optimization of tissue paper products. The deformation is modeled as a function of known product characteristics and packing process variables using data-driven models. Several modeling approaches are compared, including those based on variable selection, regularization and projection to latent variables. The data-driven model is then included into a Mixed Integer Non Linear Programming (MINLP) CLP. A worst-case robust optimization approach is considered, resulting in solutions that are robust against data-driven model uncertainty. The methodology is applied to a real case study from a portuguese tissue paper mill concerning the packing of toilet paper rolls in wood shipping pallets. Predicted results show an average gain of 4 to 7% in load density in the worst-case scenario, compared to current practice. The deformation model is validated experimentally on the industrial site, by testing optimal configurations which show gains in load density up to 40%. The methodology can be easily extended to other tissue paper products as well as any low density product showing reversible deformation during packing.

Cost Optimal Production-Scheduling Model Based on VNS-NSGA-II Hybrid Algorithm—Study on Tissue Paper Mill

With the development of the customization concept, small-batch and multi-variety production will become one of the major production modes, especially for fast-moving consumer goods. However, this production mode has two issues: high production cost and the long manufacturing period. To address these issues, this study proposes a multi-objective optimization model for the flexible flow-shop to optimize the production scheduling, which would maximize the production efficiency by minimizing the production cost and makespan. The model is designed based on hybrid algorithms, which combine a fast non-dominated genetic algorithm (NSGA-II) and a variable neighborhood search algorithm (VNS). In this model, NSGA-II is the major algorithm to calculate the optimal solutions. VNS is to improve the quality of the solution obtained by NSGA-II. The model is verified by an example of a real-world typical FFS, a tissue papermaking mill. The results show that the scheduling model can reduce production costs by 4.2% and makespan by 6.8% compared with manual scheduling. The hybrid VNS-NSGA-II model also shows better performance than NSGA-II, both in production cost and makespan. Hybrid algorithms are a good solution for multi-objective optimization issues in flexible flow-shop production scheduling.

Energy Saving for Tissue Paper Mills by Energy-Efficiency Scheduling under Time-of-Use Electricity Tariffs

Environmental concerns and soaring energy prices have brought huge pressure of energy saving and emission reduction to tissue paper mills. Electricity is one of the main energy sources of tissue paper mills. The production characteristics of tissue paper mills make it easy to decrease energy cost by using time-of-use (TOU) electricity tariffs. This study investigates the bi-objective energy-efficiency scheduling of tissue paper mills under time-of-use electricity tariffs, the objectives of which are makespan and energy cost. First, considering the processing energy cost, setup energy cost, and transportation energy cost, an energy cost model of a tissue paper mill under TOU electricity tariffs is established. Second, the energy-efficiency scheduling model under TOU electricity tariffs is built based on the energy cost model. Finally, on the basis of decomposition and teaching–learning optimization, this study proposes a novel multi-objective evolutionary algorithm and further combined with the variable neighborhood search to solve the problem. The case study results demonstrate that our study of tissue paper mill energy saving is feasible, and the proposed method has better performance than the existing methods.

Energy system optimization model for tissue papermaking process

The drying process accounts for the largest proportion of energy consumption in paper mills. Energy system optimization has a great significance for reducing the energy consumption of the paper drying process. The drying process is a complex system that consists of several subsystems, such as cylinder and air hood systems. Previous optimization models for energy systems usually focused on these subsystems. A global optimization methodology for the entire drying process is lacking, and no existing models can be applied in practice. In this work, an energy system optimization model for the tissue paper drying process is proposed based on a process simulation model. The modeling process integrates the various subsystems and fully considers the coupling of the paper drying process, which greatly enhances the industrial application value of the model. Industrial operating data are used to test the simulation model, and the results show that the simulation error of each key variable is within 5%, which meets the real-world production requirements and lays the foundation for an energy efficiency analysis of each subsystem. Applying the optimization model to a tissue paper mill, the results show that it can reduce drying costs by 8.71%.

A semi-quantitative job exposure matrix for dust exposures in Swedish soft tissue paper mills.

Total paper dust exposure has been associated with respiratory problems among workers in the soft tissue paper industry. However, a comprehensive job exposure matrix (JEM) has not been developed for application to this industry. Our study was intended to address this need and to support further studies of mortality and morbidity in a cohort of Swedish workers from this industry. We evaluated four participating soft tissue paper mills in Sweden. We combined information on process and equipment status from the mills with knowledge of the mills obtained through research efforts and paper dust measurements made at all four mills to develop a semi-quantitative JEM with seven dust exposure levels. The JEM was targeted at workers enrolled into a soft tissue paper mill cohort and working any time between 1960 and 2009. The JEM includes a total of 14 421 cells, with each cell corresponding to the exposure for a job title, department, or work location for a one-year period. Exposure levels in the JEM were estimated to decline at three of the four mills from 1971 to 2009, but overexposures (ie, exceedances of the relevant occupational exposure limits) remained common at the end of the period. The JEM results highlight the need for ongoing exposure control efforts in the soft tissue paper industry, and will inform ongoing epidemiological studies of the health effects of exposure to paper dust in Sweden. It is freely available for use by other researchers.

Energy Cost Deployment (ECD): A novel lean approach to tackling energy losses

Concerns regarding the environment have forced manufacturing organisations not only to aim for operational excellence but also to rethink how their operations and processes can become more environmentally sustainable. Companies need to decrease their unnecessary energy consumption while maintaining their productivity. Lean manufacturing is considered as one of the most influential energy management initiatives, since it increases the effective use of resources by identifying and eliminating losses. In this paper, a novel lean method called Energy Cost Deployment (ECD) is presented, whose objective are to classify, analyse, and eliminate energy losses within the factory. Modifying the well-known Manufacturing cost deployment, the novel ECD uses five matrices, which are built in sequence from the first one (i.e., A-matrix) to the last (i.e., E-matrix), in order to classify and analyse the causal factor of losses related to energy, with the focus on reducing and eliminating the greatest causal losses, and thus providing opportunities for greater efficiency. Each causal loss is quantified in monetary terms. Improvement techniques that deal with each causal loss are identified and then evaluated by means of a quantitative measure in order to find the preferable approaches. Finally, a practical decision procedure is used to select which improvement projects should be started, and hence which causal losses to tackle should be tackled, according to technical and economic factors. The effectiveness and practicality of the ECD method in tackling energy losses are illustrated using an industrial case study concerning a tissue-paper mill. Thanks to its structured step-by-step procedure, the ECD method improves the energy efficiency within a factory. • Energy Cost Deployment (ECD) is a novel Lean approach able to tackling energy losses. • The ECD method permits to improve the energy efficiency of the factory. • A novel structure to classify and analyse the energy losses is presented. • Corrective actions are prioritized according to technical and economic factors. • A case study is presented to show the practicality and effectiveness of the method.

Lung function and paper dust exposure among workers in a soft tissue paper mill

PurposeTo study respiratory effects of exposure to soft paper dust exposure, a relationship that is rarely studied.MethodsSoft tissue paper mill workers at a Swedish paper mill were investigated using a questionnaire and lung function and atopy screening. Spirometry without bronchodilation was performed with a dry wedge spirometer, and forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were obtained and expressed as percent predicted. Exposure to soft paper dust was assessed from historical stationary and personal measurements of total dust, in addition to historical information about the work, department, and production. The impact of high exposure to soft paper dust (> 5 mg/m3) vs. lower exposure ≤ 5 mg/m3, as well as cumulative exposure, was analyzed using multiple linear regression models. Multivariate models were adjusted for smoking, atopy, gender, and body mass index.ResultsOne hundred ninety-eight current workers (124 male and 74 female) were included. There were significant associations between both cumulative exposure and years of high exposure to soft paper dust and impaired lung function. Each year of high exposure to soft paper dust was associated with a 0.87% decrease in FEV1 [95% confidence interval (CI) − 1.39 to − 0.35] and decreased FVC (− 0.54%, 95% CI − 1.00 to − 0.08) compared to the lower exposed workers.ConclusionsThe present study shows that occupational exposure to soft paper dust (years exceeding 5 mg/m3 total dust) is associated with lung function impairment and increased prevalence of obstructive lung function impairment.

Integrating process optimization with energy-efficiency scheduling to save energy for paper mills

With the surging energy price and environmental concerns, measures to improve energy efficiency have attracted increasing concerns of the manufacture sector, especially energy-intensive manufacturing industries such as tissue paper mills. Energy-efficiency scheduling, as a novel energy-efficient method, has attracted the attention of an increasing number of researchers in recent years. Drying process is the most energy-intensive production process in tissue paper mills, which has a great energy-saving potential. This paper aims to reduce the energy costs for the tissue paper mill, consisting of processing energy cost and set-up energy cost, through integrating drying process optimization with energy-efficient scheduling. First, the energy cost model and the scheduling model were built. Then, the energy cost of the drying process of every job in a given scheduling problem was optimized using particle swarm optimization (PSO). Afterwards, the energy cost was further optimized using energy-efficiency scheduling. In addition, a hybrid non-dominated sorting genetic algorithm II (NSGA-II) was utilized to solve the energy-efficiency scheduling problem. Finally, several real scheduling problems from a real tissue paper mill were addressed using the proposed approach to demonstrate its effectiveness in energy saving. The experiment result showed that there is a great energy-saving potential in the drying process, accounting for up to 12.53% of the total energy consumption. Moreover, the maximum energy saving ratio of the proposed approach could reach 9.03%. On the whole, the proposed approach can provide a new energy-saving method for tissue paper mills or other manufacturing industries.

SAKARIFIKASI LUMPUR PRIMER INDUSTRI KERTAS SECARA FED BATCH MENJADI GLUKOSA UNTUK PEMBUATAN BIOETANOL (FED BATCH SACCHARIFICATION OF PRIMARY PAPER MILL SLUDGE TO PRODUCE FERMENTABLE SUGAR)

Research of fed batch saccharification using paper mill primary sludge from Waste Water Treatment Plant (WWTP) has been conducted. The research was conducted in several stages i.e. sludge characterization, determining optimum dosage of cellulase and glucosidase through batch saccharification, and continued with fed batch saccharification. The characterization was performed on 3 primary sludge type from 3 paper mill, which are print paper mill with virgin pulp raw material, paper tissue mill with virgin pulp raw material and core board mill with waste paper raw material. The characterization results showed that the sludge derived from the tissue paper mill with virgin pulp raw material has the highest content of cellulose which is 47.06%, this sludge was used as further research material. The initial trial of batch saccharification at 6% w/w and temperature of 60oC gave optimum dosage of cellulase 9 FPU/g cellulose and β-glucosidase 80 IU/g cellulose with reducing sugar 20.01 g/L and a saccharification efficiency of 63.84%. Fed batch saccharification was performed on tissue paper mill sludge at cellulase and glucosidase enzyme doses respectively 9 FPU/g cellulose and 80 IU/g, temperature 60°C and initial pH of 4 with two variables, which are cumulative solid content (10%, 14%, and 18% w/v) and feed enzyme system (at the beginning and in step). The best results were obtained at fed batch sakarifikasi with gradual enzyme feeding at 14% solids content resulting in reducing sugar 43.899 g/L and efficiency 60.03%.

Development of a Job Exposure Matrix for Noise in the Swedish Soft Tissue Paper Industry.

Noise exposure is a common occupational hazard, but has not been sufficiently characterized in paper mills. We developed a job-exposure matrix (JEM) for noise exposure for use in estimating exposures among Swedish soft tissue paper mill workers. We used a combination of area and personal dosimetry noise exposure measurements made at four soft tissue paper mills by industry and research staff between 1977 and 2013 to estimate noise exposures by department, location, and job title. We then utilized these estimates, in conjunction with information on process and facility changes and use of hearing protection collected via focus groups, to create a seven-category, semi-quantitative JEM for all departments, locations, and job titles spanning the years 1940-2010. The results of the 1157 area and personal dosimetry noise measurements indicated that noise levels have generally declined in Swedish paper mills over time, though these changes have been neither uniform nor monotonic within or across the four mills. Focus group results indicated that use of hearing protection has generally increased over time. The noise JEM totals 1917 cells, with each cell representing a unique combination of operation, job title, and single year. We estimated that ~50% of workers at the four mills assessed were exposed at or above the Swedish 8-h average noise exposure limit of an 85 dBA at the conclusion of the study period in 2010. Our results highlight the continuing need for hearing loss prevention and noise control efforts at these and similar mills, and the completed JEM now represents a tool for use in epidemiological studies of noise-related health outcomes.

Reusing tissue paper mill effluent water as corrugated paper mill intake water: Case study of a new clean production measure

To relief the water shortage crisis in China, the Chinese government has initiated a series of clean production (CP) measures to reduce the freshwater consumption and wastewater discharge from paper industry. In this study, a new CP technology was introduced in the paper industry to reuse tissue paper mill effluent water as intake water of corrugated paper mill. The feasibility and impact of the new CP technology was investigated in three different scales, laboratory experiments, pilot‐scale testing, and long‐term implementation. Results show that the water quality of treated tissue paper mill effluent water is competitive with that of freshwater and some water quality indexes are even better, indicating that treated tissue paper mill effluent water is a suitable alternative to replace the freshwater as intake water for the corrugated paper mill. By reusing tissue paper mill effluent water as intake water of corrugated paper mill, most physical properties of different corrugated paper layers are improved or similar as those by using freshwater as intake water in all different scale experiments. Moreover, the new CP technology significantly reduced the freshwater consumption for the corrugated paper mill, eliminated the wastewater discharged from the tissue paper mill, and at the same time, lowered the operation cost for both paper mills in terms of freshwater consumption and wastewater treatment cost. Total 216,000 RMB will be saved every year with an assumption that tissue paper mill provides annual daily average 2000 cubic meter of effluent water to corrugated paper mill every day. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 934–941, 2018

Mathematical modelling and energy performance assessment of air impingement drying systems for the production of tissue paper

In this paper an original and exhaustive mathematical modelling of air impingement drying systems for the production of tissue paper in the Yankee-hoods configurations is reported, which offers the possibility to optimize its energy performance. The model takes into account many detailed operative parameters of the overall drying process with the aim to execute its energy and mass balance and to evaluate its energy performances. The validity of the mathematical model has been assessed by comparison with actual data from an existing tissue paper mill. Finally, the energy performances of two different layouts of the air system have been evaluated and compared. Changing the operative parameters of the drying process, such as air jet temperature and speed and moisture content of the extraction air, it is possible to obtain the same paper production with an energy saving of about 4.5%. In average, the layout with two parallel air circuits assure an energy saving of about 1% with respect to the layout with a single air circuit.

Dinkelbach's algorithm as an efficient method to solve a class of MINLP models for large-scale cyclic scheduling problems

In this paper we consider the solution methods for mixed-integer linear fractional programming (MILFP) models, which arise in cyclic process scheduling problems. We first discuss convexity properties of MILFP problems, and then investigate the capability of solving MILFP problems with MINLP methods. Dinkelbach's algorithm is introduced as an efficient method for solving large-scale MILFP problems for which its optimality and convergence properties are established. Extensive computational examples are presented to compare Dinkelbach's algorithm with various MINLP methods. To illustrate the applications of this algorithm, we consider industrial cyclic scheduling problems for a reaction–separation network and a tissue paper mill with byproduct recycling. These problems are formulated as MILFP models based on the continuous time Resource-Task Network (RTN). The results show that orders of magnitude reduction in CPU times can be achieved when using this algorithm compared to solving the problems with commercial MINLP solvers.

Scheduling of a continuous plant with recycling of byproducts: A case study from a tissue paper mill

This paper considers an industrial scheduling problem. It involves profit maximization and the determination of the optimal cycle time, while meeting the minimum demands for the several products. Resource-Task Network-based formulations are employed and a detailed comparison between continuous- and discrete-time models is provided. Both have the improved capability of handling tasks with flexible proportions of input materials in order to consider the incorporation of different flowrates of byproducts that are recycled back to the first production stage. The continuous-time formulation is shown to be more efficient and the resulting mixed integer nonlinear program (MINLP) can be solved to optimality within reasonable computational time. A new recycling policy is proposed that achieves the double goal of making the process more profitable due to important savings on the more expensive raw-materials and also more environmentally friendly, due to the reduction of waste disposal requirements.

“Lean and Green” at a Romanian secondary tissue paper and board mill—putting theory into practice

A three-year environmental project was implemented at the Petrocart S.A. paper and board mill, through the Danish Support Programme for Eastern Europe (DANCEE). The aim was to use “Lean and Green” Production to improve industrial compliance with the effluent regulations and with EUs IPPC Directive under implementation in Romania, thereby improving the environmental conditions in the Bistrita River running through the town. The results obtained included an 87% reduction of the discharge of wastewater from 5300 to about 700 m 3/day. Previously, the effluent was subjected to primary treatment only. The reduction in flow reduced mill fibre losses and allowed discharge to an existing, underloaded, municipal treatment system, where primary and secondary treatment is operated. Further results obtained were better housekeeping (5S and Kaizen) and a Total Quality Management (TQM) organisation was implemented where product quality, environment and occupational health and safety are merged into one system. Twenty-eight TQM groups were formed, each with a representative from management and elected among workers. The mill's employment is slightly higher today, and the gross turnover and profitability has almost tripled. Had Petrocart had the financial resources themselves carried the project through without DANCEE support, the payback time for the project would have been 3.7 years for the total of €2 million spent. Petrocart no longer pays penalties for environmental non-compliance. The performance contributes to IPPC-approval. The project was implemented within the framework of DANCEE's procedures, which is based on the Logical Framework Approach (LFA) for project management. The PRojects IN Controlled Environments (PRINCE2™) model for project management was also applied. This article analyses how the results were achieved and how Lean and Green thinking as well as good project management practices, such as LFA and PRINCE2 were applied to turn around an old Eastern European company to survive privatization.

Chemical and microbiological stability of waste sludge from paper industry intended for brick production

Due to its chemical composition, waste sludge generated in the paper industry may be used as a raw material for brick production. Brick manufacture is limited to the warmer months of the year whereas sludge is produced continuously by different effluent treatment devices. Therefore, it has to be stored until further processing. For this reason, it is essential that it is not subject to significant chemical and microbiological decomposition during storage. In the experiment, sludge from a tissue paper mill was tested for its stability. It was stored for several weeks during winter and summer periods in a pile, 2 m in height, in an open but covered store. Different leachable organic and inorganic compounds indicating possible ongoing deterioration processes, as well as pH value, redox potential, temperature, humidity and dry matter content were evaluated weekly in water extracts of homogenized sludge samples. According to the test results, the material may be considered to be chemically and microbiologically stable as there was practically no emission of odorous and toxic compounds such as H2S, NH3 and butyric acid despite prolonged storage times and elevated environmental temperatures. All the microbial species identified in the sludge during storage belong to the typical microflora of the environment.