CFD Based Ash Deposition Prediction in a BFB Firing Mixtures of Peat and Forest Residue

2003 ◽  
Author(s):  
Christian Mueller ◽  
Dan Lundmark ◽  
Bengt-Johan Skrifvars ◽  
Rainer Backman ◽  
Maria Zevenhoven ◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Computational Fluid Dynamic ◽  
Power Plants ◽  
Fossil Fuels ◽  
Fluid Dynamic ◽  
Thermal Power ◽  
Biomass Combustion ◽  
Mineral Matter ◽  
Forest Residue ◽  
Bubbling Fluidized Bed

Fuels currently used for energy production in thermal power plants are characterized by their huge variety ranging from fossil fuels to biomass and waste. This multitude of fuels offers opportunities to the energy industry and nowadays many power plants do not fire either of these fuels but mixtures of them are burnt. While this procedure may lead to overall economic and environmental advantages it is very demanding for the boiler operators to still meet expectations concerning boiler performance, boiler availability and emission regulations. In the course of this latest trend in boiler operation, ash related operational problems such as slagging, fouling and corrosion are ranking very high on the list of reasons leading to significant reduction of boiler availability. Ash related problems strongly dependent on fuel specific aspects, such as the mineral matter distribution in the fuel, aspects specific to the used combustion technique as well as design aspects unique for the combustion chamber of any operating power plant. The overall goal in combustion related research is therefore the prediction of potential operational problems originating from fuel streams entering the combustion chamber as well as those originating from the design of individual furnaces. In our earlier work we have strongly focused on developing an advanced ash behavior prediction tool for biomass combustion combining computational fluid dynamic calculations (CFD) and advanced fuel analysis. In this paper the tool is applied to analyze the slagging and fouling tendency in a 295 MW bubbling fluidized bed boiler fired with mixtures of peat and forest residue. In addition to the overall deposition prediction this work focuses on details of the models used in the computational fluid dynamic calculations. These include a study on the importance of the accurate description of the fuel feeding system and related to this aspect the advanced description of the bubbling bed with regard to release of primary gas and ash particles from its surface to the freeboard. Evaluation of the predictions comparing simulation results with deposits on the furnace walls show good agreement.

scholarly journals Igniting Soaring Droplets of Promising Fuel Slurries

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 208 ◽  
Author(s):  
Alexander Bogomolov ◽  
Timur Valiullin ◽  
Ksenia Vershinina ◽  
Sergey Shevyrev ◽  
Nikita Shlegel
Keyword(s):  
Combustion Chamber ◽  
Power Plants ◽  
Alternative Fuels ◽  
Complex Geometry ◽  
Thermal Power ◽  
Combustion Chambers ◽  
Fuel Droplets ◽  
Fine Coal ◽  
Active Research ◽  
Burning Coal

High rates of environmental pollution by boilers and thermal power plants burning coal of different grades are the main reason for active research in the world aimed at the development of alternative fuels. The solution to the formulated problem acceptable in terms of environmental, technical and economic criteria is the creation of composite slurry fuels with the use of fine coal or coal processing and enrichment waste, water of different quality, and oil sludge additive. This study considers modern technologies of burning slurry fuels as well as perspective research methods of the corresponding processes. A model combustion chamber is developed for the adequate study of ignition processes. The calculation of the basic geometric dimensions is presented. The necessity of manufacturing the combustion chamber in the form of an object of complex geometry is substantiated. With its use, several typical modes of slurry fuel ignition are determined. Principal differences of ignition conditions of a single droplet and group of fuel droplets are shown. Typical vortex structures at the fuel spray injection are shown. A comparison with the trajectories of fuel aerosol droplets in real combustion chambers used for the combustion of slurry fuels is undertaken.

scholarly journals Assessment of efficiency and prospects for the use of hybrid thermal low-capacity power plants in the Republic of Vietnam

2019 ◽  
Vol 124 ◽  
pp. 01040 ◽  
Author(s):  
D. T. Nguen ◽  
D. N. Pham ◽  
G. R. Mingaleeva ◽  
O. V. Afanaseva ◽  
P. Zunino
Keyword(s):  
Power Plants ◽  
Fossil Fuels ◽  
Renewable Energy Sources ◽  
Thermal Power ◽  
Climatic Conditions ◽  
Energy Sources ◽  
Thermal Power Plants ◽  
Basic Design ◽  
Air Heating ◽  
The Republic

The growing demand for energy and fossil fuels creates increased number of difficulties, while renewable energy sources are still rarely used worldwide, particularly in Vietnam. In this article hybrid thermal power plants based on gas turbine plants are discussed, the increased efficiency of which is achieved by air heating after the compressor in solar air heaters. The basic design equations and the results of evaluating the efficiency and fuel consumption are presented for two thermal power plants of 4.6 MW and 11.8 MW. The dependence of the results on the intensity of solar extraction for the climatic conditions of the Ninh Thuan province of the Republic of Vietnam is discussed.

scholarly journals Editorial

2019 ◽  
Vol 18 (2) ◽  
pp. 02
Author(s):  
Diogo Berta Pitz
Keyword(s):  
Gas Turbines ◽  
Power Plants ◽  
Fossil Fuels ◽  
Industrial Revolution ◽  
Thermal Power ◽  
Steam Generators ◽  
Computing Power ◽  
Energy Demands ◽  
Residential Use ◽  
Engineering Projects

Since the Industrial Revolution mankind has been interested in obtaining energy from various sources in order to fulfill its ever-increasing energy demands for industrial, commercial and residential use. Fortunately, we have been able to produce energy in quantities that permit technological innovations and the spread of existing technologies around the world. Such success is due not only to the search for alternatives to fossil fuels, but also to the development of devices that allow fuels to be used in rational, efficient ways. The refinement of equipment that improve our lives – from refrigeration devices used in residential applications to steam generators and gas turbines employed to generate electricity in thermal power plants – is only possible due to physical understanding of processes such as heat transfer, combustion, fluid flow dynamics and thermodynamic systems. Physical modeling of such phenomena provides tools for optimization of engineering projects, which ultimately results in an efficient use of the energy resources available. In an era where the computing power available allows us to analyze models that are ever more faithful to the physical behavior of real processes, we have the ability to push existing technologies to ever-increasing limits of energy efficiency and to explore the viability of new processes.

scholarly journals Beyond Strict Regulations to Achieve Environmental and Economic Health—An Optimal PM2.5 Mitigation Policy for Korea

2020 ◽  
Vol 17 (16) ◽  
pp. 5725
Author(s):  
Kyungwon Park ◽  
Taeyeon Yoon ◽  
Changsub Shim ◽  
Eunjin Kang ◽  
Yongsuk Hong ◽  
...  
Keyword(s):  
Air Quality ◽  
Computable General Equilibrium ◽  
Power Plants ◽  
Fossil Fuels ◽  
Thermal Power ◽  
Computable General Equilibrium Model ◽  
Policy Paradigm ◽  
Korean Economy ◽  
High Dependency ◽  
Pm2.5 Emissions

Growing concern about particulate matter (PM2.5) pressures Korea to reduce the health risks associated with its high dependency on fossil fuels. The Korean economy relies heavily on large thermal power plants—a major source of PM2.5 emissions. Although air quality regulations can negatively impact local economies, the Korean government announced two strict air quality mitigation policies in 2019. We develop a regional static computable general equilibrium model to simulate the economic and environmental impacts of these polices under alternative hypothetical scenarios. We separate two regions, Chungcheongnam-do, the most polluted region, and the rest of the country, in our model. As policy options, we introduce a regional development tax and a tradable market for PM emission permits, similar to an air pollution tax and a carbon permits market, respectively. The results show that allowing higher tax rates and a tradable permits market gives the optimal combination, with the PM2.5 emissions reduced by 2.35% without sacrificing economic growth. Since alternative options present, for example, a 0.04% loss of gross domestic product to reduce PM emissions by the same amount, our results here may present a new policy paradigm for managing air pollutants such as PM2.5.

Thermo-Fluid Dynamic of Gaseous Pollutant Dispersion: Fundamentals and Applications in Thermal Power Plants

2018 ◽  
Vol 20 ◽  
pp. 34-54
Author(s):  
A.J. Ferreira Gadelha ◽  
T.R. Nascimento Porto ◽  
T.H. Freire de Andrade ◽  
Severino Rodrigues de Farias Neto ◽  
A.G. Barbosa de Lima
Keyword(s):  
Wind Velocity ◽  
Power Plants ◽  
Fluid Dynamic ◽  
Thermal Power ◽  
Pollutant Dispersion ◽  
Thermal Power Plants ◽  
Cfd Simulations ◽  
Gaseous Pollutant ◽  
Ansys Cfx ◽  
Dispersion Problem

This work focuses on the pollutant dispersion problem with particular reference to thermal power plants. A powerful mathematical modeling to predict gaseous pollutant concentration at atmosphere and different CFD simulations results by Ansys CFX®software are presented. The gaseous pollutant dispersion was evaluated by analyzing of different process parameters as wind velocity, gas emission rate and temperature. The study confirms wind velocity as main variable that strongly affecting dispersion phenomena.

scholarly journals Measuring the Ecological Efficiency of Thermal Power Plants: Evidence from Pakistan

2020 ◽  
Vol 37 (1) ◽  
pp. 159-184
Author(s):  
Imran Qaiser ◽  
Theocharis Grigoriadis
Keyword(s):  
Power Plants ◽  
Fossil Fuels ◽  
Thermal Power ◽  
Returns To Scale ◽  
Material Balance ◽  
Environmental Benefits ◽  
Fuel Oil ◽  
Data Envelopment ◽  
Balance Principle ◽  
Residual Fuel Oil

This paper assesses the environmental and economic efficiency of thermal plants operating on fossil fuels in Pakistan using methods based on data envelopment analysis. Using the material balance principle, we find that cost- and carbon-efficient points can only be obtained simultaneously by switching to gas. However, under an assumption of variable returns to scale, these points can still be obtained without this conversion through the application of best practices. Furthermore, about 26% of costs and about 34% of carbon emissions can be reduced without a switch to gas, but instead by using technically efficient inputs; this approach can also lead to a significant reduction in electricity prices and considerable environmental benefits. Power plants operating on residual fuel oil are significantly more technically efficient than plants operating on gas. Nonetheless, both types of plants have an equal share in forming the metafrontier as exhibited by the meta-technology ratio. There is a definite need to make plants more efficient by using the best possible combination of inputs and overhauling. Bootstrap results also suggest that further improvement in efficiency is possible.

Numerical Simulation of the Combustion Behavior of Different Biomasses in a Bubbling Fluidized Bed Boiler

2005 ◽  
Author(s):  
Christian Mueller ◽  
Anders Brink ◽  
Mikko Hupa
Keyword(s):  
Fluidized Bed ◽  
Power Plants ◽  
Thermal Power ◽  
Combustion Process ◽  
Fluidised Bed ◽  
Simplified Approach ◽  
Combustion Behavior ◽  
Bubbling Bed ◽  
Bubbling Fluidized Bed ◽  
Fuel Mixtures

Solid fuels currently used for energy production in thermal power plants are characterized by a large variety ranging from different coals to biomasses and wastes. This manifold of fuels offers opportunities to the energy producers and nowadays many power plants do not fire single fuels but fuel mixtures. While this procedure may lead to overall economic and environmental advantages it is very demanding for the boiler operators to maintain boiler performance and availability and to meet emission limits. The development of mathematical models that are capable of predicting the combustion behavior of fuel mixtures and provide guidelines for operators and manufacturers has been a challenge over the last years. Since bubbling fluidized beds are frequently used for firing fuel mixtures and especially biomass mixtures, current CFD based BFB models, such as the A˚bo Akademi Furnace Model, have been used widely over the last years to predict emission tendencies and ash deposition behavior. However, due to the complexity of the processes during combustion of fuel mixtures and the combustion process in the bubbling fluidised bed itself, the models are characterized by strong simplifications. This is especially true for the description of the lower part of the furnace, the region of fuel intake and bubbling bed. Recently, the A˚bo Akademi Furnace Model has been extended by a more detailed description of the fuel conversion by considering the combustion of individual biomass particles and a first simplified approach describing heat and mass transfer processes between the bubbling bed and the freeboard. Both submodels guarantee a closed mass and energy balance over the bed-freeboard region. In the current study the new submodels have been used to investigate the combustion conditions in a 290 MW bubbling fluidized bed boiler firing peat and forest residue. Clear differences in the simulation results for the both fuels can be found with regard to the specific combustion characteristics, the location of the main combustion zone and the total heat generated during combustion.

scholarly journals Influence of Activators on Mechanical Properties of Modified Fly Ash Based Geopolymer Mortars

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1033 ◽  
Author(s):  
Piotr Prochon ◽  
Zengfeng Zhao ◽  
Luc Courard ◽  
Tomasz Piotrowski ◽  
Frédéric Michel ◽  
...  
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Thermal Power ◽  
Biomass Combustion ◽  
Fly Ashes ◽  
Binding Properties ◽  
Alkali Activated ◽  
Modified Fly Ash ◽  
Scanning Electron ◽  
And Calorimetry

The aim of this work was to study the influence of the type of activator on the formulation of modified fly ash based geopolymer mortars. Geopolymer and alkali-activated materials (AAM) were made from fly ashes derived from coal and biomass combustion in thermal power plants. Basic activators (NaOH, CaO, and Na2SiO3) were mixed with fly ashes in order to develop binding properties other than those resulting from the use of Portland cement. The results showed that the mortars with 5 mol/dm3 of NaOH and 100 g of Na2SiO3 (N5-S22) gave a greater compressive strength than other mixes. The compressive strengths of analyzed fly ash mortars with activators N5-S22 and N5-C10 (5 mol/dm3 NaOH and 10% CaO) varied from 14.3 MPa to 5.9 MPa. The better properties of alkali-activated mortars with regular fly ash were influenced by a larger amount of amorphous silica and alumina phases. Scanning electron microscopy and calorimetry analysis provided a better understanding of the observed mechanisms.

Scenario Analysis of Denitration for Chinese Coal-Fired Power Generation

2015 ◽  
Vol 814 ◽  
pp. 425-429 ◽  
Author(s):  
Xian Ce Meng ◽  
Chen Li ◽  
Su Ping Cui ◽  
Li Li Zhao ◽  
Xian Zheng Gong ◽  
...  
Keyword(s):  
Power Generation ◽  
Scenario Analysis ◽  
Power Plants ◽  
Fossil Fuels ◽  
Catalytic Reduction ◽  
Thermal Power ◽  
Power Industry ◽  
Nox Emissions ◽  
Technology Applications ◽  
Chinese Coal

The environmental loads are made due to the natural resources and fossil fuels use and pollutants emissions by Chinese thermal power industry. To explore the realistic coal-fired power generation and its denitration strategies, the input and output of coal-fired power generation in China were identified and quantified. The scope of this paper is defined in the boundary of coal-fired electricity generation system all over China. The methodology follows the principal of ISO 14040 and ISO 14044. The functional unit is “1 kWh of electricity generated”. The inventory data of Chinese coal-fired power generation in 2009 without denitration technology applications were measured. The output data include the CO, N2O, CH4, CO2, NOx, PM and SO2 emissions. NOx emissions are the major contributor of acidification and photochemical in China. To avoid catastrophic environmental damages, the air pollution especially NOx emissions from coal-fired power plants are advised to be cut. For scenario analysis, in the assumption of 100%of selective non-catalytic reduction (SNCR) technology applications, China still has denitration potential. In the coming several decades, the SNCR technology will be decisive for the Chinese coal-fired power industry to reach deeper NOx emission reductions. However, the reduction agents of ammonia and urea usage bring ammonia slip, and extra natural resource and fossils consumption. The urea use also brings extra CO2 emissions. This limits the applications of SNCR technology to reduce NOx emissions.

Thick Plates in Grade 91 for Fourth Generation Nuclear Reactors

2010 ◽  
Author(s):  
Sylvain Pillot ◽  
Zhao Zhao ◽  
Ste´phanie Corre ◽  
Ce´dric Chauvy ◽  
Lionel Coudreuse ◽  
...  
Keyword(s):  
Power Plants ◽  
Nuclear Energy ◽  
Fossil Fuels ◽  
Thermal Power ◽  
Chromium Steel ◽  
Operating Conditions ◽  
Fourth Generation ◽  
Thick Plates ◽  
The Future ◽  
Grade 91

To face the future challenge of global energy supply, taking into account the depletion of fossil fuels and global warming issues, the main nuclear energy users are strongly involved in a research program to fourth-generation reactor technology. This new generation will work at high temperatures between about 450 °C and 550 °C. Extensive studies have been launched worldwide to assess steel grades able to meet these new operating conditions. One of the candidates is Vanadium enhanced 9% Chromium steel grade (EN 10028-2 X11CrMoVNb 9-1 – ASTM A387 grade 91 class 2 – ASME SA387 grade 91 class 2). To meet the future needs in nuclear energy, Industeel improved its conventional 9Cr1MoVNb steel devoted to the fabrication of steam lines in thermal power plants. Preliminary studies revealed the feasibility of thick plates in this enhanced grade. Thick plates, 140 and 210 mm thick, have been hot rolled from a 82 metric tons ingot. Welded joints have then been prepared. Tests performed on both base metal and welded zones proved the excellent mechanical properties of the grade, especially regarding toughness property. This work demonstrated the industrial feasibility of very thick plates made of grade 91 for nuclear applications. This contribution is a review of the work done as well as the results obtained on the plates.

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