scholarly journals The control of condensate in the dryer cylinders by their temperature gradient coolings

2020 ◽  
Author(s):  
В.П. Сиваков ◽  
А.В. Вураско
Keyword(s):  
Measurement Errors ◽  
Temperature Gradients ◽  
Control Points ◽  
Steam Consumption ◽  
Paper Drying ◽  
Cooling Period ◽  
Paper Machines ◽  
Measurement Mode ◽  
Technical Maintenance ◽  
Permissible Levels

Дроссельные шайбы, применяемые в сушильных цилиндрах (СЦ) для выпуска конденсата, имеют нерегулируемый условный проход, что приводит при интенсификации теплового и гидравлического режимов работы к накоплению конденсата. Повышенное содержание конденсата в СЦ увеличивает термическое сопротивление тепловому потоку от конденсирующегося пара к внутренним стенкам СЦ. Разработка методов обнаружения повышенного содержания конденсата в отдельных цилиндрах актуальна для снижения расхода пара на сушку бумаги. Выполнены исследования трендов температуры СЦ (скорости изменения температуры по времени, °С/мин) за период охлаждения после отключения подачи пара. Выбраны диагностические точки контроля и обоснован режим измерения температур в этих точках СЦ. Произведено исключение грубых ошибок экспериментов. Разработана методика и алгоритм расчета допустимых уровней трендов температур. Выполнены расчеты допустимых характеристик трендов температур за время интервалов охлаждения СЦ. По трендам температур определены СЦ с повышенным содержанием конденсата. Разработанный авторами метод и алгоритм расчета допустимых трендов температур охлаждения СЦ при останове машины, основанный на различиях в скорости охлаждения СЦ с конденсатом и без конденсата, теоретически обоснован и экспериментально апробирован в производственных условиях. Обнаружение СЦ с повышенным содержанием конденсата по данному методу можно производить параллельно с другими работами по технологическому и техническому обслуживанию сушильных частей бумагоделательных машин. Throttle washers used in drying cylinders (DC) for condensate release have an unregulated conditional passage, which leads to the accumulation of condensate during the intensification of thermal and hydraulic modes. The condensate accumulates in DS due to the tolerances of the scale uneven. The increased condensate content in the DC increases the thermal resistance to the heat flow from the condensing steam to the internal walls of the DC. Studies of temperature gradients during the cooling period after the steam supply to the drying cylinders has been performed. The method and algorithm of calculation of permissible levels of temperature gradients are developed. Drying cylinders with increased condensate level were determined. The development of methods for detecting increased condensate content in individual cylinders is relevant for reducing the steam consumption for paper drying. Studies of temperature gradients of the DC during the cooling period after the steam supply was switched off in the drying part of the boom-making machine were performed. Diagnostic control points are selected and the temperature measurement mode in the DC these points is justified. The exception of gross errors of experiments on the t-criterion Student's was made. A method and algorithm for calculating the permissible levels of temperature gradients and the minimum and maximum permissible temperature deviations of the surveyed SCS has been developed. A graph is constructed for detecting and excluding rough measurement errors from the sample. Calculations of permissible characteristics of temperature gradients during cylinder cooling intervals are performed. By temperature gradients during cooling intervals, DC with an increased condensate content are determined. The method and algorithm developed by the authors for calculating the permissible levels of cooling temperature gradients of the DC, when the machine is stopped, based on differences in the cooling rate of the DC with condensate and without condensate, is theoretically justified and experimentally tested in production conditions. Detection of DC with high condensate content using this method can be performed in parallel with other works on technological and technical maintenance of drying parts of paper machines.

scholarly journals Machine Learning-Based Energy System Model for Tissue Paper Machines

Processes ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 655
Author(s):  
Huanhuan Zhang ◽  
Jigeng Li ◽  
Mengna Hong
Keyword(s):  
Neural Network ◽  
Energy Consumption ◽  
Gradient Boosting ◽  
Paper Machine ◽  
Steam Consumption ◽  
Tissue Paper ◽  
Paper Machines ◽  
Energy Consumption Model ◽  
Extreme Gradient Boosting ◽  
Consumption Model

With the global energy crisis and environmental pollution intensifying, tissue papermaking enterprises urgently need to save energy. The energy consumption model is essential for the energy saving of tissue paper machines. The energy consumption of tissue paper machine is very complicated, and the workload and difficulty of using the mechanism model to establish the energy consumption model of tissue paper machine are very large. Therefore, this article aims to build an empirical energy consumption model for tissue paper machines. The energy consumption of this model includes electricity consumption and steam consumption. Since the process parameters have a great influence on the energy consumption of the tissue paper machines, this study uses three methods: linear regression, artificial neural network and extreme gradient boosting tree to establish the relationship between process parameters and power consumption, and process parameters and steam consumption. Then, the best power consumption model and the best steam consumption model are selected from the models established by linear regression, artificial neural network and the extreme gradient boosting tree. Further, they are combined into the energy consumption model of the tissue paper machine. Finally, the models established by the three methods are evaluated. The experimental results show that using the empirical model for tissue paper machine energy consumption modeling is feasible. The result also indicates that the power consumption model and steam consumption model established by the extreme gradient boosting tree are better than the models established by linear regression and artificial neural network. The experimental results show that the power consumption model and steam consumption model established by the extreme gradient boosting tree are better than the models established by linear regression and artificial neural network. The mean absolute percentage error of the electricity consumption model and the steam consumption model built by the extreme gradient boosting tree is approximately 2.72 and 1.87, respectively. The root mean square errors of these two models are about 4.74 and 0.03, respectively. The result also indicates that using the empirical model for tissue paper machine energy consumption modeling is feasible, and the extreme gradient boosting tree is an efficient method for modeling energy consumption of tissue paper machines.

Investigation of Flashing Flow in a Siphon to Extract Condensate in Paper Dryer Application

2019 ◽  
Author(s):  
Hamed Abdul Majeed ◽  
Ting Wang
Keyword(s):  
Cfd Simulation ◽  
Paper Industry ◽  
Volume Ratio ◽  
Piping System ◽  
Drying Process ◽  
Local Pressure ◽  
Steam Consumption ◽  
Paper Drying ◽  
Computational Fluid Dynamics Cfd ◽  
State Case

Abstract The paper industry uses steam to dry paper web through cylinder dryers. As steam condenses inside the cylinder dryer, the condensate is removed by means of either a stationary or a rotary siphon. However, during the siphoning process for transporting the condensate, flashing of the condensate occurs, which could cause backflow or discontinuity in the siphoning process. To resolve this flashing issue, two approaches have been employed: (a) increasing the amount of steam supplied to the cylinder to “blow-through” the stalled condensate-steam mixture and (b) reducing the back pressure by inducing “suction” through a thermocompressor from downstream. This practice of employing push from the upstream and suction from the downstream requires excessively large amounts of high-grade steam, resulting in an estimated 10 to 15 %, 15 to 25%, and 40 to 90 % of blow-through steam for stationary siphons, rotary siphons, and Yankee dryers respectively. The objective of this study is to investigate and improve understanding of the flashing phenomena during condensate transport through the siphon and piping system in order to develop means to reduce this excessive steam consumption during the paper drying process. A computational fluid dynamics (CFD) simulation is performed that uses the Eulerian-Eulerian multiphase method. The steady-state case is first solved to obtain the flow field without flashing. Then the transient method is initiated by employing flashing and condensation models. The results show that reduction of local pressure triggers flashing, however, flashing in turn reduces local temperature, and subsequently induces condensation, resulting in an alternating flashing and condensation behavior. To maintain continuity of the siphon flow, the inlet pressure fluctuates corresponding to the variation of total vapor volume ratio inside the siphon. The results will be used to modify the current siphon system design and operating practices to reduce steam consumption.

CHALLENGES AND METHODS IN ANALYZES OF THE HEAT TRANSFER IN POLYMER DRY BEARINGS

Tribologia ◽  
2018 ◽  
Vol 282 (6) ◽  
pp. 71-78
Author(s):  
Krzysztof KASZA ◽  
Łukasz MATYSIAK ◽  
Artur KRÓL
Keyword(s):  
Numerical Model ◽  
Measurement Errors ◽  
Temperature Sensors ◽  
Temperature Gradients ◽  
Maximum Temperature ◽  
Large Temperature ◽  
Internal Temperature ◽  
Require Temperature ◽  
Polymer Bearing ◽  
Load Conditions

Heat generation and dissipation in dry polymer bearings are important aspects in their design and operation, because the overheating may lead to fast wear or product damage. The estimation of the maximum temperature under defined load conditions is crucial, but it is also a challenging task. Firstly, it is difficult to measure temperature directly at the contact surface between the bearing and the shaft. Secondly, thermocouples that are commonly used as the temperature sensors might create measurement errors. The work presented in this paper utilizes the numerical model of a polymer bearing for the analysis of the internal temperature field. The model is validated with use of experimental data; and, in order to mitigate the measurement errors of the thermocouple sensor, their geometry and properties are included in the simulation model. The achieved agreement between simulation and experimental temperatures is 10% on average, and it is judged that the numerical model may be applied for thermal analysis of the polymer bearing. The obtained results confirm the influence of the thermocouples with metallic sheaths on the temperature distribution inside the tested polymer bearing. It is shown that the value of the measurement errors depends on the layout of thermocouples and might be significantly reduced by their proper arrangement. It is believed that the presented approach for the analysis of thermal performance of dry polymer bearings might be applied to similar cases, which are characterized by large temperature gradients and require temperature sensors, that are made of the materials of high thermal conductivity.

scholarly journals Increase of the energy efficiency in paper industry

2008 ◽  
Vol 62 (4) ◽  
pp. 233-245
Author(s):  
Milorad Krgovic ◽  
Vladimir Valent ◽  
Marina Krsikapa ◽  
Miodrag Milojevic ◽  
Branko Raseta ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Energy Efficiency ◽  
Energy Consumption ◽  
Specific Heat ◽  
Paper Industry ◽  
Electric Energy ◽  
Paper Drying ◽  
Improve Energy Efficiency ◽  
Electric Energy Consumption ◽  
Paper Machines

In this work, phenomena of heat and mass transfer in process of paper drying are given, certain technology units are analyzed, while possibility for decrease of specific heat and electric energy consumption by modernization of technology is examined. Some of the solutions applied on paper machines worldwide in order to improve energy efficiency are shown. Theoretic and practical discoveries in this area are applied in Board factory UMKA, and these results are shown in the work as well.

scholarly journals Mode effect analysis in the case of daily passenger mobility survey

2020 ◽  
Vol 6 (2) ◽  
pp. 43-57
Author(s):  
Vasilij Centrih ◽  
Andrej Viršček ◽  
Andreja Smukavec ◽  
Nataša Bučar ◽  
Marta Arnež
Keyword(s):  
Data Collection ◽  
Measurement Errors ◽  
Complex Data ◽  
Online Questionnaire ◽  
Effect Analysis ◽  
Collection Process ◽  
Data Collection Process ◽  
Mode Effect ◽  
Measurement Mode ◽  
The Republic

AbstractIn the autumn 2017, The Statistical Office of the Republic of Slovenia (SURS) has conducted for the first time a survey on daily passenger mobility of Slovenian residents. The key statistics are on persons’ daily traveling habits, such as number of trips, travelled distance, time spent on traveling, and so on. Two independent samples were selected for the simultaneous collection of data by two modes, face-to-face interview (CAPI) and online questionnaire (WEB). The goal of this study is to identify the possible sources of mode measurement errors, with the objective to better design and thus improve the whole data collection process. The detailed mode effect analysis is performed by the comparison of the key statistic estimates and the use of regression models. Usually the measurement mode effect is an issue in surveys on the more sensitive topics or persons’ opinions. This work points out that, first, the mode measurement effect can be an issue also in a more factual survey content, and second, the corresponding statistical data processes can have an important contribution to minimising measurement errors. The results show that WEB respondents are inclined to join two or more trips into one reported, which gives lower estimate of average number of daily trips. The main reason is the demanding questionnaire content. Additionally, the complex data editing process was still insufficient to correct completely for such measurement error. The possible improvements of the data collection process are also discussed.

Investigation of Flashing Flow in a Siphon to Extract Condensate in Paper Dryer Application

2020 ◽  
pp. 1-24
Author(s):  
Hamed Abdul Majeed ◽  
Ting Wang
Keyword(s):  
Cfd Simulation ◽  
Paper Industry ◽  
Volume Ratio ◽  
Piping System ◽  
Drying Process ◽  
Local Pressure ◽  
Steam Consumption ◽  
Paper Drying ◽  
Computational Fluid Dynamics Cfd ◽  
State Case

Abstract The paper industry uses steam to dry paper web through cylinder dryers. As steam condenses inside the dryer, the condensate is removed by means of either a stationary or a rotary siphon. However, during the siphoning process for transporting the condensate, flashing of the condensate occurs, which could cause backflow or discontinuity in the siphoning process. To resolve this flashing issue, two approaches have been employed: (a) increasing the amount of steam supplied to the cylinder to “blow-through- the stalled condensate-steam mixture and (b) reducing the back pressure by inducing “suction- through a thermocompressor from downstream. The objective of this study is to investigate and improve understanding of the flashing phenomena during condensate transport through the siphon and piping system in order to develop means to reduce the excessive steam consumption during the paper drying process. A computational fluid dynamics (CFD) simulation is performed that uses the Eulerian-Eulerian multiphase method. The steady-state case is first solved to obtain the flow field without flashing. Then the transient method is initiated by employing flashing and condensation models. The results show that reduction of local pressure triggers flashing; however, flashing in turn reduces local temperature, and subsequently induces condensation, resulting in an alternating flashing and condensation behavior. To maintain continuity of the siphon flow, the inlet pressure fluctuates corresponding to the variation of total vapor volume ratio inside the siphon. The results will be used to modify the current siphon system design and operating practices to reduce steam consumption.

Control Scheme for Stock Approach System of Chinese High Speed Tissue Machine

2015 ◽  
Vol 734 ◽  
pp. 237-241
Author(s):  
Wei Tang ◽  
Qi Wang ◽  
Zhi Yong Pei ◽  
Yu Yang Lian ◽  
Zhen Wang
Keyword(s):  
High Speed ◽  
Control Points ◽  
Fuzzy Pid ◽  
Tissue Paper ◽  
Paper Machines ◽  
Control Scheme ◽  
And Control

The stock approach system of Chinese high speed tissue paper machines and the configuration of measuring and control points are specified. After introducing the control of absolute dry pulp quantity, the control scheme of Fuzzy-PID composite is implemented. The application result indicates that the scheme proposed is feasible and effective

Practical Realization of a Reference System for Earth Dynamics by Satellite Methods

1975 ◽  
Vol 26 ◽  
pp. 341-380 ◽  
Author(s):  
R. J. Anderle ◽  
M. C. Tanenbaum
Keyword(s):  
Reference Frame ◽  
Polar Motion ◽  
Pole Position ◽  
Control Points ◽  
Significant Information ◽  
Crustal Motion ◽  
Average Reference ◽  
Future Data ◽  
Existing Data

AbstractObservations of artificial earth satellites provide a means of establishing an.origin, orientation, scale and control points for a coordinate system. Neither existing data nor future data are likely to provide significant information on the .001 angle between the axis of angular momentum and axis of rotation. Existing data have provided data to about .01 accuracy on the pole position and to possibly a meter on the origin of the system and for control points. The longitude origin is essentially arbitrary. While these accuracies permit acquisition of useful data on tides and polar motion through dynamio analyses, they are inadequate for determination of crustal motion or significant improvement in polar motion. The limitations arise from gravity, drag and radiation forces on the satellites as well as from instrument errors. Improvements in laser equipment and the launch of the dense LAGEOS satellite in an orbit high enough to suppress significant gravity and drag errors will permit determination of crustal motion and more accurate, higher frequency, polar motion. However, the reference frame for the results is likely to be an average reference frame defined by the observing stations, resulting in significant corrections to be determined for effects of changes in station configuration and data losses.

Precise on-line Measurement of Lattice Vectors

1990 ◽  
Vol 48 (1) ◽  
pp. 530-531
Author(s):  
W.J. de Ruijter ◽  
Sharma Renu
Keyword(s):  
Electron Microscope ◽  
Measurement Errors ◽  
Dynamic Range ◽  
Structural Information ◽  
Statistical Parameter ◽  
Systematic Errors ◽  
Geometric Distortion ◽  
Crystal Silicon ◽  
Camera System ◽  
On Line

Established methods for measurement of lattice spacings and angles of crystalline materials include x-ray diffraction, microdiffraction and HREM imaging. Structural information from HREM images is normally obtained off-line with the traveling table microscope or by the optical diffractogram technique. We present a new method for precise measurement of lattice vectors from HREM images using an on-line computer connected to the electron microscope. It has already been established that an image of crystalline material can be represented by a finite number of sinusoids. The amplitude and the phase of these sinusoids are affected by the microscope transfer characteristics, which are strongly influenced by the settings of defocus, astigmatism and beam alignment. However, the frequency of each sinusoid is solely a function of overall magnification and periodicities present in the specimen. After proper calibration of the overall magnification, lattice vectors can be measured unambiguously from HREM images.Measurement of lattice vectors is a statistical parameter estimation problem which is similar to amplitude, phase and frequency estimation of sinusoids in 1-dimensional signals as encountered, for example, in radar, sonar and telecommunications. It is important to properly model the observations, the systematic errors and the non-systematic errors. The observations are modelled as a sum of (2-dimensional) sinusoids. In the present study the components of the frequency vector of the sinusoids are the only parameters of interest. Non-systematic errors in recorded electron images are described as white Gaussian noise. The most important systematic error is geometric distortion. Lattice vectors are measured using a two step procedure. First a coarse search is obtained using a Fast Fourier Transform on an image section of interest. Prior to Fourier transformation the image section is multiplied with a window, which gradually falls off to zero at the edges. The user indicates interactively the periodicities of interest by selecting spots in the digital diffractogram. A fine search for each selected frequency is implemented using a bilinear interpolation, which is dependent on the window function. It is possible to refine the estimation even further using a non-linear least squares estimation. The first two steps provide the proper starting values for the numerical minimization (e.g. Gauss-Newton). This third step increases the precision with 30% to the highest theoretically attainable (Cramer and Rao Lower Bound). In the present studies we use a Gatan 622 TV camera attached to the JEM 4000EX electron microscope. Image analysis is implemented on a Micro VAX II computer equipped with a powerful array processor and real time image processing hardware. The typical precision, as defined by the standard deviation of the distribution of measurement errors, is found to be <0.003Å measured on single crystal silicon and <0.02Å measured on small (10-30Å) specimen areas. These values are ×10 times larger than predicted by theory. Furthermore, the measured precision is observed to be independent on signal-to-noise ratio (determined by the number of averaged TV frames). Obviously, the precision is restricted by geometric distortion mainly caused by the TV camera. For this reason, we are replacing the Gatan 622 TV camera with a modern high-grade CCD-based camera system. Such a system not only has negligible geometric distortion, but also high dynamic range (>10,000) and high resolution (1024x1024 pixels). The geometric distortion of the projector lenses can be measured, and corrected through re-sampling of the digitized image.

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