scholarly journals Digital Model of Boiler Furnace Processes

2021 ◽  
Vol 21 (2) ◽  
pp. 26-32
Keyword(s):  
Thermal Power ◽  
Digital Technologies ◽  
Regulatory Elements ◽  
Digital Model ◽  
Computer Assisted ◽  
Gas Temperature ◽  
Boiler Furnace ◽  
Factors Affecting ◽  
Standard Values ◽  
Account Temperature

The normative method (NM) of thermal boiler calculation, which has been confirmed and refined multiple times, contains the structure of ideas and methods retained and adapted during the transition to digital technologies. As applied to the analysis of thermal processes in the boiler furnace with flare furnaces, this required the transformation of a large array of initial and reference data, which cannot be used unchanged in digital technologies, including computer-assisted. This applies to graphical and tabular data, which occupy up to 80% of the NM volume. The main regulatory elements of the digital model in this case are the temperature of adiabatic combustion of the fuel, the coefficient of attenuation of radiation by the combustion medium, the degree of emissivity of the furnace taking into account the size of the radiating layer, the coefficient of thermal efficiency of the furnace wall pipings, the resulting Boltzmann number and the final calculated value of the gas temperature at the exit from the furnace. The use of specific data for a boiler with D = 400 t/h made it possible to clarify the structure of analytical dependencies, as well as the magnitude of deviations from the standard values in the final temperature values. The paper presents a developed transition to dependencies accounting for the thermal power of the boiler and the type of fuel. The digital model adaptation to the boiler conditions with all types of fuel in use made it possible to determine the average deviations of the final parameters. Quantitatively, the entire material corresponds to the normative data, is presented digitally and corresponds methodically to the Mathcad-15 package. In contrast to acclaimed works in this area, all factors affecting the heat balance are represented by approximations taking into account temperature variability.

scholarly journals Simulating combustion processes based on digital technologies

2018 ◽  
Vol 44 ◽  
pp. 00043 ◽  
Author(s):  
Marsel Kadyrov ◽  
Maria Khabarova ◽  
Alexander Khabarov ◽  
Alexei Trinchenko
Keyword(s):  
Power Plants ◽  
Coal Dust ◽  
Thermal Power ◽  
Digital Technologies ◽  
Mathematic Model ◽  
Furnace Operation ◽  
Diffusion Kinetic ◽  
Boiler Furnace ◽  
Future Challenges ◽  
Dust Flame

The thermal power plants (TPP) make a basis of power-generation industry of the majority of countries. The global growth of power consumption and the policy of energy-saving demand to increase the efficiency of plants operation, which is, among others, determined by the technical level of steam-generating units. The up-to-date digital technologies make it possible to assess the efficiency of boiler furnace operation at the stage of boiler unit designing, its reconstruction or retrofitting and upgrading. Developed in the article are the algorithm, mathematic model and computer program of calculating diffusion-kinetic process of combustion of D-grade Donetsk coal in the coal-dust flame of boiler Е-230-14,0-520. The assigned tasks have been solved by using theoretical methods of analysis, the capabilities of devices of computer-aided calculations have utilized for visualization of results. The considered digital approach to solving technical tasks makes it possible to meet the current and future challenges.

Analysis into Abnormal Factors Affecting the Ash Discharge Amount of Thermal Power Plant

2013 ◽  
Vol 664 ◽  
pp. 1012-1017
Author(s):  
Gang Chen ◽  
Wei Su ◽  
Tian Shen Chen
Keyword(s):  
Coal Sample ◽  
Electrostatic Precipitator ◽  
Discharge Rate ◽  
Thermal Power ◽  
Coal Ash ◽  
Moisture Loss ◽  
Boiler Furnace ◽  
Factors Affecting ◽  
Different Temperatures ◽  
Measurement Deviation

An ash yield experiment and a coal ash component analysis with the same coal sample at different temperatures showed that when a coal sample burned in a boiler furnace whose temperature was higher than 815 ° C, part of the salts (eg, sulfate) and oxides (eg, SO3) would continue to be decomposed, resulting in the actual ash yield of the coal sample decreasing compared with the theoretical ash discharge rate. At the same time, the analysts pointed out that the moisture loss and its representative defects of the as-fired coal sampling machine system, the dust removal efficiency fluctuation of the electrostatic precipitator, and the measurement deviation of the as-fired coal quantity also caused the actual ash discharge rate to be on is low side.

scholarly journals Computer-Assisted System in Stress Radiography for Anterior Cruciate Ligament Injury with Correspondent Evaluation of Relevant Diagnostic Factors

Diagnostics ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 419
Author(s):  
Chien-Kuo Wang ◽  
Liang-Ching Lin ◽  
Yung-Nien Sun ◽  
Cheng-Shih Lai ◽  
Chia-Hui Chen ◽  
...  
Keyword(s):  
Diagnostic Accuracy ◽  
Cruciate Ligament ◽  
Anterior Tibial Translation ◽  
Computer Assisted ◽  
Time Interval ◽  
Stress Radiography ◽  
Factors Affecting ◽  
Anterior Tibial ◽  
Anterior Cruciate ◽  
Tibial Translation

We sought to design a computer-assisted system measuring the anterior tibial translation in stress radiography, evaluate its diagnostic performance for an anterior cruciate ligament (ACL) tear, and assess factors affecting the diagnostic accuracy. Retrospective research for patients with both knee stress radiography and magnetic resonance imaging (MRI) at our institution was performed. A complete ACL rupture was confirmed on an MRI. The anterior tibial translations with four different methods were measured in 249 patients by the designed algorithm. The diagnostic accuracy of each method in patients with all successful measurements was evaluated. Univariate logistic regression analysis for factors affecting diagnostic accuracy of method four was performed. In the inclusive 249 patients, 177 patients (129 with completely torn ACLs) were available for analysis. Mean anterior tibial translations were significantly increased in the patients with a completely torn ACL by all four methods, with diagnostic accuracies ranging from 66.7% to 75.1%. The diagnostic accuracy of method four was negatively associated with the time interval between stress radiography and MRI as well as force-joint distance on stress view, and not significantly associated with age, gender, flexion angle, intercondylar distance, and force-joint angle. A computer-assisted system measuring the anterior tibial translation in stress radiography showed acceptable diagnostic performance of complete ACL injury. A shorter time interval between stress radiography and MRI as well as shorter force-joint distance were associated with higher diagnostic accuracy.

scholarly journals Numerical Calculations of WR-40 Boiler Based on its Zero-Dimensional Model

2014 ◽  
Vol 35 (2) ◽  
pp. 173-180 ◽  
Author(s):  
Bartłomiej Hernik
Keyword(s):  
Numerical Model ◽  
Flue Gases ◽  
Balance Model ◽  
Furnace Chamber ◽  
Gas Temperature ◽  
Cfd Modelling ◽  
Boiler Furnace ◽  
Average Temperature ◽  
Furnace Outlet ◽  
Dissipation Model

Abstract Generally, the temperature of flue gases at the furnace outlet is not measured. Therefore, a special computation procedure is needed to determine it. This paper presents a method for coordination of the numerical model of a pulverised fuel boiler furnace chamber with the measuring data in a situation when CFD calculations are made in regard to the furnace only. This paper recommends the use of the classical 0-dimensional balance model of a boiler, based on the use of measuring data. The average temperature of flue gases at the furnace outlet tk" obtained using the model may be considered as highly reliable. The numerical model has to show the same value of tk" . This paper presents calculations for WR-40 boiler. The CFD model was matched to the 0-dimensional tk" value by means of a selection of the furnace wall emissivity. As a result of CFD modelling, the flue gas temperature and the concentration of CO, CO2, O2 and NOx were obtained at the furnace chamber outlet. The results of numerical modelling of boiler combustion based on volumetric reactions and using the Finite-Rate/Eddy-Dissipation Model are presented.

scholarly journals Experimental study of the thermochemical treatment of the low-grade coal prior to boiler combustion at coal-fired power station

2019 ◽  
Vol 109 ◽  
pp. 00119
Author(s):  
Volodymyr Yemelianenko ◽  
Vitalii Pertsevyi ◽  
Oleksandr Zhevzhyk ◽  
Iryna Potapchuk ◽  
Oleksandr Lutai
Keyword(s):  
Experimental Study ◽  
Power Plants ◽  
Thermal Power ◽  
Thermochemical Treatment ◽  
Gas Pressure ◽  
Pulverized Coal ◽  
Time Range ◽  
Low Grade ◽  
Boiler Furnace ◽  
Coal Fuel

Analysis of the perspectives of the coal fuel for thermal power plants is carried out. The necessity of the experimental study for temperature measurement in the boiler furnace. The results of the experimental study are presented: temperature change over time at the burner outlet for different constant pressure value of the backlighting gas, dependence of the temperature at the burner outlet from the backlighting gas pressure for constant concentration value of pulverized coal in coal-air mixture, dependence of the temperature at the burner outlet from the concentration of pulverized coal in coal-air mixture for constant value of the backlighting gas pressure, temperature measurements for constant backlighting gas pressure value, constant value of the concentration of pulverized coal in coal-air mixture when plasmatron is switched and operates for some time range. The results of the study could be applied to the solid fuel treatment for different thermal units.

scholarly journals STUDY OF THE OXIDATION PROCESS OF NITROGEN OXIDES BY OZONE

2021 ◽  
pp. 62-70
Author(s):  
I.A. Volchyn ◽  
O.M. Kolomiets ◽  
S.V. Mezin ◽  
A.O. Yasynetskyi
Keyword(s):  
Nitrogen Oxides ◽  
Conversion Efficiency ◽  
Power Plants ◽  
Oxidation Process ◽  
Thermal Power ◽  
Nitrogen Monoxide ◽  
Molar Ratio ◽  
Gas Temperature ◽  
Gas Treatment ◽  
Industrial Enterprises

The need to reduce emissions of pollutants, in particular nitrogen oxides, as required by regulations in Ukraine, requires the use of modern technologies and methods for waste gas treatment at industrial enterprises. This is especially true of thermal power plants, which are powerful sources of nitrogen oxide emissions. The technological part of the wet or semi-dry method of purification is the area for the oxidation of nitrogen oxides to obtain easily soluble compounds. The paper presents the results of a study of the process of ozone oxidation of nitrogen oxides in a chemical reactor. Data for the analysis of the process were obtained by performing physical experiments on a laboratory installation and related calculations on a mathematical model. Studies of the oxidation process have shown that the required amount of ozone depends not only on the content of nitrogen monoxide, but also on the content of nitrogen dioxide. The process of conversion of nitrogen monoxide to a satisfactory level occurs at the initial value of the molar ratio of ozone to nitrogen monoxide in the range of 1.5…2. The conversion efficiency of nitrogen monoxide reaches 90% at a gas temperature less than 100 °C. To achieve high conversion efficiency at gas temperatures above 100 °C, it is necessary to increase the initial ozone content when the molar ratio exceeds 2. The analysis shows that the conversion efficiency of nitric oxide largely depends on the residence time of the gas mixture in the reaction zone. Due to lack of time under certain conditions, the efficiency decreases by approximately 46%. To increase it, it is necessary to accelerate the rate of oxidation reactions due to better mixing of gases by turbulence of the flow in the oxidizing reactor. Bibl. 6, Fig. 6, Tab. 3.

scholarly journals Assessment of Negative Factors Affecting the Intestinal Microbiota in People with Excessive Body Mass Compared to People with Normal Body Mass

Proceedings ◽  
2020 ◽  
Vol 61 (1) ◽  
pp. 5
Author(s):  
Karolina Osowiecka ◽  
Natalia Pokorna ◽  
Damian Skrypnik
Keyword(s):  
Physical Activity ◽  
Body Mass ◽  
Intestinal Microbiota ◽  
P Value ◽  
Computer Assisted ◽  
Factors Affecting ◽  
Normal Body ◽  
Activity Frequency ◽  
As Stress ◽  
Negative Factors

Rationale: Intestinal microbiota plays a significant role in the human body. A range of negative factors may lead to dysbiosis, which results in many diseases (e.g., cancer) and metabolic disorders. It was shown that people with a body mass index (BMI) of ≥25 kg/m2 present diminished microbial diversity. Additional negative factors such as stress, the use of non-steroidal anti-inflammatory drugs (NSAID) and proton pomp inhibitors (PPI) may result in greater dysbiosis compared to people with normal body mass. The aim of the study was to compare the incidence of negative factors affecting the intestinal microbiota in people with excessive body mass vs. people with normal body mass. Methods: The study involved volunteers aged 18–65 years: 582 people with normal BMI (18.5–24.99 kg/m2) and 538 people with BMI ≥ 25 kg/m2. The study was conducted using the author’s survey by the Computer-Assisted Web Interviewing method. The survey included the questions on sociodemographic features, level of physical activity, frequency of smoking, and stress. Frequency of NSAID and PPI use was also investigated. BMI was used to assess nutritional status. For statistics the Fisher test was implemented. p-Value < 0.05 was considered significant. Results: Women predominated in the study (p < 0.0001). People with normal BMI had a significantly higher level of physical activity (p < 0.0001) and smoked less (p = 0.0356). People with excessive body mass were less likely to report illness (p = 0.0004), but more often they took PPI (p = 0.0337). Conclusions: People with BMI ≥ 25 kg/m2 present more factors which may result in dysbiosis and lead to dysbiosis-related health problems in future compared to people with normal BMI.

scholarly journals Improving the efficiency of power boilers by cooling the flue gases to the lowest possible temperature under the conditions of safe operation of reinforced concrete and brick chimneys of power plants

2018 ◽  
Vol 245 ◽  
pp. 07014 ◽  
Author(s):  
Evgeny Ibragimov ◽  
Sergei Cherkasov
Keyword(s):  
Reinforced Concrete ◽  
Power Plant ◽  
Flue Gas ◽  
Power Plants ◽  
Thermal Power ◽  
Operating Mode ◽  
Flue Gases ◽  
Technical Solution ◽  
Gas Temperature ◽  
Safe Operation

The article presents data on the calculated values of improving the efficiency of fuel use at the thermal power plant as a result of the introduction of a technical solution for cooling the flue gases of boilers to the lowest possible temperature under the conditions of safe operation of reinforced concrete and brick chimneys with a constant value of the flue gas temperature, when changing the operating mode of the boiler.

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