A novel approach to white liquor control in a continuous digester using the Box-Jenkins methodology to predict chip bulk density

TAPPI Journal ◽  
2015 ◽  
Vol 14 (6) ◽  
pp. 395-402
Author(s):  
FLÁVIO MARCELO CORREIA ◽  
JOSÉ VICENTE HALLAK D’ANGELO ◽  
SUELI APARECIDA MINGOTI
Keyword(s):  
Bulk Density ◽  
Moving Average ◽  
Pulp Mill ◽  
Statistical Decision ◽  
White Liquor ◽  
Novel Approach ◽  
Cooking Process ◽  
Eucalyptus Kraft Pulp ◽  
Relevant Variables ◽  
Kraft Cooking

Alkali charge is one of the most relevant variables in the continuous kraft cooking process. The white liquor mass flow rate can be determined by analyzing the chip bulk density fed to the process. At the mills, the total time for this analysis usually is greater than the residence time in the digester. This can lead to an increasing error in the mass of white liquor added relative to the specified alkali charge. This paper proposes a new approach using the Box-Jenkins methodology to develop a dynamic model for predicting chip bulk density. Industrial data were gathered on 1948 observations over a period of 12 months from a Kamyr continuous digester at a bleached eucalyptus kraft pulp mill in Brazil. Autoregressive integrated moving average (ARIMA) models were evaluated according to different statistical decision criteria, leading to the choice of ARIMA (2,0,2) as the best forecasting model, which was validated against a new dataset gathered during 2 months of operations. A combination of predictors has shown more accurate results compared to those obtained by laboratory analysis, allowing a reduction of around 25% of the chip bulk density error to the alkali addition amount.

scholarly journals Consequences in a softwood kraft pulp mill of initial high alkali concentration in the impregnation stage

2019 ◽  
Vol 34 (1) ◽  
pp. 28-35 ◽  
Author(s):  
Elisabet Brännvall ◽  
Ida Kulander
Keyword(s):  
Kraft Pulp ◽  
Pulp Mill ◽  
Alkali Concentration ◽  
Pulp Yield ◽  
Kraft Pulp Mill ◽  
White Liquor ◽  
High Initial Concentration ◽  
Softwood Kraft Pulp ◽  
High Alkali ◽  
Energy Balances

Abstract Impregnation with high initial concentration is fast and efficient, leading to a homogeneous delignification in the subsequent cook, resulting in improved screened pulp yield. To obtain high initial alkali concentration, the white liquor flow needs to be significantly increased. The moisture content of the wood chips and the alkali concentration of the white liquor limit the initial alkali concentration of the impregnation liquor that can be reached. It is therefore of interest to evaluate the possibility to implement high alkali impregnation (HAI) industrially and the consequences this would have on the mill system. The effect of HAI on mass and energy balances in a kraft pulp mill has been studied using mill model simulations. The sensitivity to disturbances in important parameters for process control has been compared to impregnation scenarios used industrially. It was shown that high initial alkali concentration can be achieved on industrial scale by increased white liquor flow. HAI has a positive effect on recovery flows and reduces the need for make-up chemicals. The HAI concept is less sensitive to variations in process parameters, such as chip moisture and white liquor concentration, thus diminishing the risk of alkali depletion in chip cores.

Biorefinery in a pulp mill: simultaneous production of cellulosic fibers from Eucalyptus globulus by soda-anthraquinone cooking and surface-active agents

Holzforschung ◽  
2013 ◽  
Vol 67 (5) ◽  
pp. 481-488 ◽  
Author(s):  
Marion Sanglard ◽  
Christine Chirat ◽  
Bevan Jarman ◽  
Dominique Lachenal
Keyword(s):  
Eucalyptus Globulus ◽  
Pulp Mill ◽  
Wood Chips ◽  
Oxygen Delignification ◽  
Cellulosic Fibers ◽  
Surface Active Agents ◽  
Cooking Temperature ◽  
Kraft Cooking ◽  
Surface Active ◽  
The Impact

Abstract Industrial Eucalyptus globulus wood chips were submitted to different autohydrolysis conditions followed by kraft cooking and soda-anthraquinone cooking. The autohydrolyzed wood chips were much easier to delignify than the control wood chips. Soda-anthraquinone cooking could be performed at a cooking temperature that was 20°C lower than that for the kraft cooking on control wood chips. Furthermore, the active alkali could be reduced. The resulting unbleached pulps reacted as well to oxygen delignification as the control pulps and could be further bleached to 90% ISO brightness with a D(EP)D sequence. The autohydrolysis liquors were investigated for their suitability as a source for the synthesis of alkylpolyxylosides (APX). These surface-active agents are synthesized through the reaction between the saccharides of the autohydrolysates and a fatty alcohol, with the former being the hydrophilic and the latter being the hydrophobic part of the molecule. The impact of the substances detected in autohydrolysates on the APX synthesis was studied. It was demonstrated that lignin dissolved during autohydrolysis should at least partially be removed before the production of APX.

Grey system based novel approach for stock market forecasting

2015 ◽  
Vol 5 (2) ◽  
pp. 178-193 ◽  
Author(s):  
R.M. Kapila Tharanga Rathnayaka ◽  
D.M.K.N Seneviratna ◽  
Wei Jianguo
Keyword(s):  
Time Series ◽  
Prediction Models ◽  
Stock Exchange ◽  
Moving Average ◽  
Grey Prediction ◽  
Grey System ◽  
Short Term ◽  
Content Type ◽  
Stock Market Forecasting ◽  
Novel Approach

Purpose – Making decisions in finance have been regarded as one of the biggest challenges in the modern economy today; especially, analysing and forecasting unstable data patterns with limited sample observations under the numerous economic policies and reforms. The purpose of this paper is to propose suitable forecasting approach based on grey methods in short-term predictions. Design/methodology/approach – High volatile fluctuations with instability patterns are the common phenomenon in the Colombo Stock Exchange (CSE), Sri Lanka. As a subset of the literature, very few studies have been focused to find the short-term forecastings in CSE. So, the current study mainly attempted to understand the trends and suitable forecasting model in order to predict the future behaviours in CSE during the period from October 2014 to March 2015. As a result of non-stationary behavioural patterns over the period of time, the grey operational models namely GM(1,1), GM(2,1), grey Verhulst and non-linear grey Bernoulli model were used as a comparison purpose. Findings – The results disclosed that, grey prediction models generate smaller forecasting errors than traditional time series approach for limited data forecastings. Practical implications – Finally, the authors strongly believed that, it could be better to use the improved grey hybrid methodology algorithms in real world model approaches. Originality/value – However, for the large sample of data forecasting under the normality assumptions, the traditional time series methodologies are more suitable than grey methodologies; especially GM(1,1) give some dramatically unsuccessful results than auto regressive intergrated moving average in model pre-post stage.

scholarly journals Gradient Artefact Correction and Evaluation of the EEG Recorded Simultaneously with fMRI Data Using Optimised Moving-Average

2016 ◽  
Vol 2016 ◽  
pp. 1-17 ◽  
Author(s):  
José L. Ferreira ◽  
Yan Wu ◽  
René M. H. Besseling ◽  
Rolf Lamerichs ◽  
Ronald M. Aarts
Keyword(s):  
Moving Average ◽  
Fmri Data ◽  
Accurate Information ◽  
High Temporal Resolution ◽  
Eeg Signal ◽  
Novel Approach ◽  
Aas Method ◽  
Average Filter ◽  
Artefact Correction

Over the past years, coregistered EEG-fMRI has emerged as a powerful tool for neurocognitive research and correlated studies, mainly because of the possibility of integrating the high temporal resolution of the EEG with the high spatial resolution of fMRI. However, additional work remains to be done in order to improve the quality of the EEG signal recorded simultaneously with fMRI data, in particular regarding the occurrence of the gradient artefact. We devised and presented in this paper a novel approach for gradient artefact correction based upon optimised moving-average filtering (OMA). OMA makes use of the iterative application of a moving-average filter, which allows estimation and cancellation of the gradient artefact by integration. Additionally, OMA is capable of performing the attenuation of the periodic artefact activity without accurate information about MRI triggers. By using our proposed approach, it is possible to achieve a better balance than the slice-average subtraction as performed by the established AAS method, regarding EEG signal preservation together with effective suppression of the gradient artefact. Since the stochastic nature of the EEG signal complicates the assessment of EEG preservation after application of the gradient artefact correction, we also propose a simple and effective method to account for it.

scholarly journals POTENSI SERAT DAN PULP BAMBU UNTUK KOMPOSIT PEREDAM SUARA

2016 ◽  
Vol 4 (01) ◽  
Author(s):  
Theresia Mutia ◽  
Susi Sugesty ◽  
Henggar Hardiani ◽  
Teddy Kardiansyah ◽  
Hendro Risdianto
Keyword(s):  
Sound Absorption ◽  
Natural Fiber ◽  
Bamboo Fiber ◽  
Reference Frequency ◽  
Reinforced Composites ◽  
Synthetic Fibers ◽  
Sound Absorber ◽  
Cooking Process ◽  
Extractive Substances ◽  
Kraft Cooking

Natural fiber-reinforced composites can reduce the use of synthetic fibers and resins, making them more environmentally friendly. Bamboo fiber is a long fiber from non woody plant with a shorter growing season than wood. A study has been conducted to investigate the potential of bamboos, which are endemic in West Java, namely Tali bamboo (G. apus), Temen bamboo (G. pseudoarundinacea) and Haur bamboo/Green ampel (B. vulgaris v. Green), as sound absorber composite materials. Bamboo contains 21% - 22 % lignin, 44% - 53% alpha cellulose, 21% - 23% hemicelluloses, which makes it a potential pulp feedstock. Because of the adhesive nature of lignin, it is necessary to produce a pulp with a Kappa number of about 30 (+ 5% lignin). In accordance with bamboo characteristics, Tali bamboo requires less amount of cooking chemicals due to its lower contents of extractive substances and lignin, whereas Temen bamboo and especially Haur bamboo require more chemicals. Therefore, tali bamboo was chosen to produce pulp by Kraft cooking process. Subsequently, bamboo fiber was prepared by soda cooking process at the same conditions. Later on, some trial experiments with epoxy resin were performed to make sound absorber composites. The results show that at the reference frequency (5000 Hz) the pulp and bamboo fiber composites provide the maximum sound absorption coefficients (α) of 0.28 and 0.77, respectively. Hence, the composite meets the minimum standard of sound absorption coefficient of ISO 11654:1997 (α = 0.25). Moreover, the composite of epoxy and bamboo fiber is light (specific gravity <1) with an ability to reduce 97% of the sound at 2500 Hz.Keywords : fiber and pulp bamboo, nonwood, sound absorber composite, sound absorption coefficien  ABSTRAK Komposit berpenguat serat alam, dapat mengurangi pemakaian serat sintetis dan resin, sehingga lebih ramah lingkungan. Serat bambu termasuk serat panjang non kayu dengan masa tanam lebih singkat dibanding kayu. Penelitian terhadap bambu endemik Jawa Barat, yaitu bambu Tali (G. apus), Temen (G. pseudoarundinacea) dan Haur/Ampel hijau (B. vulgaris v. green), dilakukan untuk mengetahui potensinya sebagai komposit peredam suara. Dari hasil uji diketahui bahwa bambu tersebut mengandung lignin 21% - 22%, selulosa alfa 44% - 53% dan hemiselulosa 21% - 23%, serta merupakan serat panjang yang berpotensi untuk menghasilkan pulp yang baik. Lignin pada pulp untuk bahan komposit masih diperlukan, sehubungan dengan sifatnya sebagai perekat, sehingga dilakukan penelitian untuk menghasilkan pulp bambu dengan bilangan Kappa sekitar 30 (lignin + 5%). Atas dasar karakteristiknya, pemasakan bambu Tali akan memerlukan zat kimia yang terendah karena kandungan zat ekstraktif dan lignin yang lebih rendah, sedangkan bambu Temen dan terutama Haur sebaliknya memerlukan zat kimia yang lebih tinggi. Oleh karenanya dipilih bambu Tali untuk dilanjutkan pada pembuatan pulp dengan pemasakan proses Kraft dan untuk mendapatkan seratnya dilakukan pemasakan dengan proses soda pada kondisi sama, yang kemudian dilakukan uji coba pembuatan komposit peredam suara dengan resin epoksi. Dari hasil uji diketahui bahwa pada frekuensi acuan (5000 Hz) komposit pulp dan serat bambu memberikan koefisien serap bunyi maksimum (α) sebesar 0,28 dan 0,77, berarti dapat memenuhi standar minimal koefisien serap bunyi sesuai ISO 11654:1997 (α = 0,25), terutama komposit epoksi/serat bambu, karena mampu meredam suara sampai 97% pada frekuensi 2500 Hz, dan lebih ringan (berat jenisnya < 1).Kata kunci: serat dan pulp bambu, non kayu, komposit peredam suara, koefisien serap bunyi

scholarly journals Algoritma Pemilihan Objek pada Interaksi Antarmuka Berbasis Titik Pandang Mata

2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Herlina Herlina
Keyword(s):  
Linear Regression ◽  
Eye Movement ◽  
Smooth Pursuit ◽  
Moving Average ◽  
Similarity Measures ◽  
Object Selection ◽  
Interactive Applications ◽  
Smooth Pursuit Eye Movement ◽  
Novel Approach ◽  
Dynamic Stimulus

Eye tracking provides an alternative input modality to control the interactive contents in computers, particularly in assistive technology and public display. Instead of fixational eye movement, smooth pursuit eye movement has been used for object selection in gaze-based interactive applications. However, some previous works did not consider various similarity measures to match trajectory of eye movement and the presented dynamic stimulus. Furthermore, there was no correction towards the drift of eye movement during object selection. Hence, gaze-based object selection based on smooth pursuit eye movement is still inaccurate and unstable. To fill the research gaps, we proposed a novel approach for accurate gaze-based object selection using linear regression for eye movement’s drifting correction. We measured accuracy, success timing, and stability of object selection to validate performance of the proposed method. From the experimental results, object selection could be performed without the usage of chinrest using Euclidean distance, moving average and linear regression in gaze-based interfaces. The usage of chinrest did not give significant effect on accuracy, success timing and stability of object selection in gaze-based interfaces. The use of linear regression for predicting gaze points and correcting drift of eye movement has improved overall performance of object selection .In future, our results maybe used as a guideline for developing more accurate and more stable interactive applications based on smooth pursuit eye movement.

Case Study on Simultaneous Gasification of Black Liquor and Biomass in a Pulp Mill

1998 ◽  
Author(s):  
Mikael Ahlroth ◽  
Gunnar Svedberg
Keyword(s):  
High Efficiency ◽  
Black Liquor ◽  
Pulp Mill ◽  
Energy System ◽  
Limiting Factors ◽  
Fuel Quality ◽  
Hybrid Energy ◽  
Novel Approach ◽  
Substantial Investment ◽  
A Minor

One of the main limiting factors when a green field pulp mill intends to increase its production is the capacity of the Tomlinson boiler by which the cooking chemicals are recovered. Since a boiler of this kind has a service life of some thirty years and represents a substantial investment, it is not an easy decision to replace it for a minor production increase. This study takes a novel approach to the problem. The excess black liquor is assumed to be recovered in a black liquor gasifier, an emerging technology for alternative black liquor recovery. Black liquor gasification in itself has been studied considerably during the last decade. In this study it is combined with the gasification of biomass, i.e. bark and wood, which is already available at a pulp mill. The resulting hybrid energy system, with a gas turbine and a gas expander, offers interesting possibilities: good off-design performance and high efficiency with respect to the fuel quality.

The chemical versus energy cost tug of war: A pulp mill perspective

TAPPI Journal ◽  
2011 ◽  
Vol 10 (7) ◽  
pp. 37-42 ◽  
Author(s):  
PETER W. HART
Keyword(s):  
Low Cost ◽  
Laboratory Data ◽  
Pulp Mill ◽  
Simulation Models ◽  
Operating Conditions ◽  
Operating Point ◽  
Cost Constraints ◽  
Cooking Process ◽  
Wide Range ◽  
The Impact

As the cost of energy and processing chemicals changes, the optimal, lowest cost operating conditions within a pulp mill also change. Additionally, the optimal cost operating point within one area of the mill may not result in a total mill low cost operation. Three practical pulp mill examples have been analyzed under varying cost constraints for energy and chemicals to determine the impact of energy and chemical cost changes on the low cost operating point. These examples include changing the digester kappa number target, changing the brownstock washing dilution factor, and the conversion of a continuous digester from one type of cooking process to a lower energy cooking process. Selected mill operating results and laboratory data were employed to tune various process simulation models to obtain cost predictions over a wide range of operating conditions.

Online monitoring of inorganic cooking chemicals in white liquor by pulse voltammetry

TAPPI Journal ◽  
2010 ◽  
Vol 9 (8) ◽  
pp. 49-53
Author(s):  
ROBERT B. BJORKLUND ◽  
DAN LOUTHANDER ◽  
PER MÅRTENSSON ◽  
STAFFAN ANDERSSON ◽  
ERLAND KVIST ◽  
...  
Keyword(s):  
Online Monitoring ◽  
Pulp Mill ◽  
Partial Least Square ◽  
Least Square ◽  
Partial Least Square Regression ◽  
Mean Squared Errors ◽  
White Liquor ◽  
Pulse Voltammetry ◽  
Relative Root ◽  
Shift Personnel

White liquor parameters in the recovery area of a kraft pulp mill were monitored for a 1-year period using rhodium as an electrode material in a sensor system based on pulse voltammetry. Shift personnel performed offline titration analysis of the liquor every 4 hours. The results for effective alkali, sulfidity, and total titratable alkali were used to train and validate the sensor for online monitoring. Partial least square regression models developed from 150 reference titration results for each parameter from the first month of the study predicted concentrations for the following 11 months. Validation of the models using titration results indicated that overall relative root mean squared errors for prediction of the parameters were 3.7% for effective alkali, 3.4% for sulfidity, and 5.1% for total titratable alkali. Process stops that exposed the sensor to temperature excursions or acid washings resulted in temporary periods of poor prediction.

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