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.

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.

Effect of Burner and Resonator Impedances on the Acoustic Behavior of Annular Combustion Chambers

2006 ◽  
Author(s):  
Annalisa Forte ◽  
Sergio Camporeale ◽  
Bernardo Fortunato ◽  
Francesca Di Bisceglie ◽  
Marco Mastrovito
Keyword(s):  
Numerical Simulations ◽  
Combustion Chamber ◽  
Structural Damage ◽  
Acoustic Pressure ◽  
Acoustic Analysis ◽  
Complex Geometry ◽  
Connected Components ◽  
Acoustic Behavior ◽  
Combustion Chambers ◽  
Helmholtz Resonators

Premixed combustion is the commonly adopted technique to reduce NOx emissions from gas turbine combustion chambers, but it has been proved to be susceptible to thermo-acoustic instabilities, known as humming. These self-excited oscillations can reduce the efficiency of the turbine and generate structural damage to the combustion chamber. One of the proposed suppression methods lies in the application of Helmholtz resonators to the combustion chambers. This passive technique is advantageous in carrying out appreciable oscillation damping with modest costs and long life, but it is effective only in a restricted range of frequency, close to resonator eigenfrequency. Therefore, in order to design effective resonators, it is necessary to know the eigenfrequencies of the annular combustion chamber, because combustion instabilities arise in correspondence of these frequencies. Acoustic analysis of combustion chamber and its connected components may be carried out by means of Finite Element Method, but it requires a considerable computational effort due to the complex geometry of the complete system, which needs to be meshed by a refined grid. A combined numerical and experimental technique allows the authors to increase computational efficiency by adopting coarser and more regular meshes. First acoustic behavior of annular combustion chamber has been studied by means of numerical simulations and, therefore, the influence of the burners has been taken into account by substituting burner geometries by experimentally measured acoustic impedances. Then some Helmholtz resonators, tuned to one eigenfrequency of the combustion chamber, have been designed and manufactured. Their acoustic impedances have been experimentally measured and applied as boundary conditions into FE simulations of the annular chamber. In this way the acoustic pressure field inside the damper-equipped combustion chamber has been analyzed. Numerical simulations of the annular chamber, with burner and damper impedances applied, show that Helmholtz resonators are effective in oscillation suppression in correspondence of their resonance frequency, but may produce the splitting of the acoustic pressure peak of the chamber into two new peaks, whose frequencies lie on either side of the original common eigenfrequency. The amplitudes of these two new pressure peaks appear lower than the amplitude of the baseline one. The proposed technique can be used as an effective design tool: acoustic analysis of annular combustion chamber, with burner impedance applied, produces accurate indications about its acoustic behavior and allows the design of new passive suppression systems and the evaluation of their performances.

Characteristics of Deposits in Gas Turbine Combustion Chambers Using Synthetic and Conventional Jet Fuels

2013 ◽  
Vol 135 (7) ◽  
Author(s):  
Greg Pucher ◽  
William Allan ◽  
Pierre Poitras
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Alternative Fuels ◽  
Large Scale ◽  
Aviation Fuel ◽  
Jet Fuels ◽  
Combustion Chambers ◽  
Fuel Blend ◽  
Synthetic Fuel ◽  
Camelina Oil

The synthetic fuel industry is poised to experience large-scale growth and profoundly affect current aviation fuel infrastructure. New candidate technologies, such as Camelina oil-derived synthetic fuel have been demonstrated to not only provide satisfactory quasi drop-in characteristics for conventional fuels, but in life cycle analysis studies have also been shown to potentially offer positive improvements relative to conventional feedstocks with respect to economic, environmental, and land use considerations. As part of a multiyear study at the Royal Military College of Canada to evaluate combustion related parameters of fuel additives and alternative fuels for gas turbine applications, a Camelina-derived synthetic fuel blend was assessed to determine potential combustion related benefits as compared to conventional and other synthetic blends. The Combustion Chamber Sector Rig (CCSR) which houses a Rolls Royce T-56-A-15 combustion section was utilized for the evaluation of emissions and deposits. Following combustion testing, several combustion system components, including the combustion chamber, fuel nozzle, and igniter plug were analyzed for relative levels of deposit build-up. As with other Fischer Tropsch derived synthetic fuels, there were positive benefits found with Camelina blends in terms of emissions performance and deposit production tendencies.

scholarly journals Universal Combustion Chamber for Utilization of Petroleum Gases of Different Composition and Heat Output

2021 ◽  
Author(s):  
Alena Shilova ◽  
◽  
Nikolai Bachev ◽  
Oleg Matyunin ◽  
◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Power Plants ◽  
Energy Balance Equation ◽  
Working Fluid ◽  
Heat Output ◽  
Combustion Chambers ◽  
Fuel Gas ◽  
Excess Air ◽  
Secondary Air

When developing micro-gas turbine power plants, it is necessary to have universal two-zone combustion chambers for utilizing petroleum gases of different composition and heat output at different oil deposits. In the combustion zone, the excess air ratio is selected from the interval between the lower and upper concentration limits of combustion. In the dilution zone by supplying secondary air, the working fluid with specified parameters is prepared for supply to the turbine. The excess air coefficient at the exit from the combustion chamber is determined from the energy balance equation and depends on the air and fuel gas parameters at the entrance to the combustion chamber and on the temperature of the working fluid at the entrance to the turbine. The purpose of this work is to develop recommendations for creating a universal combustion chamber for combustion of fuel gases of different composition and heat output. This goal is achieved by selecting the diameter of the chamber in order to ensure the required ratios between the average flow rate of the combustible air mixture and the rate of turbulent combustion, at which a stable position of the flame front is observed. The most noticeable result of the research conducted is substantiation of the possibility of using a universal combustion chamber with constant dimensions in utilization gas turbine installations designed for burning nonstandard fuel gases with ballasting components content up to 70%, which will reduce the time and cost of development and implementation of these installations.

scholarly journals Use of class C fly ash for stabilization of fine-grained soils

2020 ◽  
Vol 195 ◽  
pp. 06001
Author(s):  
Canan Turan ◽  
Akbar Javadi ◽  
Raffaele Vinai ◽  
Nader Shariatmadari ◽  
Raziyeh Farmani
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Soil Stabilization ◽  
Clayey Soil ◽  
Thermal Power ◽  
Fine Grained ◽  
Alternative Material ◽  
Stabilized Soil ◽  
Class C ◽  
Burning Coal

Fine-grained soils may have undesired characteristics such as high swelling potential and low strength, thus requiring improvements. One of the stabilization methods involves the use of fly ash. Fly ash is a waste material obtained from burning coal in thermal power plants. The use of fly ash is encouraged as an alternative material for soil stabilization, due to its features such as pozzolanic properties and economic availability. This paper describes the results of an experimental study on stabilization of a clayey soil with fly ash. Unconfined compressive strength (UCS), triaxial and consolidation tests were carried out on samples of kaolinite mixed with class C fly ash at different percentages and cured for 1, 7, and 28 days, in order to study the effects of class C fly ash on the mechanical behaviour of the stabilized soil. The results showed that the inclusion of fly ash significantly improves the strength characteristics of the soil. Curing time was also found to have a significant effect on improving the properties of the soil.

Experimental and Numerical Investigation of Different Flame Types Inside a Laboratory Scale RQL Combustion Chamber

2019 ◽  
Author(s):  
Thomas von Langenthal ◽  
Nikolaos Zarzalis ◽  
Marco Konle
Keyword(s):  
Flow Field ◽  
Combustion Chamber ◽  
Thermal Power ◽  
Measurement Techniques ◽  
Flame Structure ◽  
Operating Conditions ◽  
Test Rig ◽  
Combustion Chambers ◽  
Primary Zone ◽  
Secondary Air

Abstract RQL (rich burn, quick quench, lean burn) combustion chambers are common in modern aero engines due to their low NOx emissions and good stability. The rich primary zone leads to lower flame temperatures and in combination with the lack of oxygen, the NOx production is low. The mixing of the secondary air must be quick in order to avoid stoichiometric conditions and at the same time must ensure the oxidation of the soot produced in the fuel rich primary zone to keep soot emissions to a minimum. However, the design of such a combustion chamber is complicated due to the complex interaction between the swirling primary flow and the jets of the secondary airflow. In this paper, we present a new test rig, which was designed to study combustion processes inside RQL combustion chambers at atmospheric conditions. The test rig features liquid kerosene combustion and a realistic quenching zone as well as good access for optical and conventional measurement techniques. For realistic engine like conditions the combustion air is preheated to 600 K and the fuel–air equivalence ratio in the primary combustion zone is set to be between Φ = 1.66 and Φ = 1.25, resulting in an overall thermal power between 80 kW and 110 kW. To get insights into the complex flow field inside the combustion chamber unsteady RANS simulations of both the reacting and the non-reacting case were performed using OpenFOAM. The turbulent flow field was modeled using the k-ω-SST model and the combustion was simulated using the Partially Stirred Reactor model. The experimental investigations showed two stable flame types for the same operating conditions with considerable differences in the visible flame structure and soot radiation. The flow field of both of these flame types were measured using a 1.5 kHz 2D PIV System. The numerical simulations showed good overall agreement with the experimental results but could not represent the change in flame type. In order to understand the underlying effects of the flame change the OH* chemiluminescence was recorded and the two-phase flow near the nozzle exit was investigated. This showed that the change in flame structure might arise due to spray dispersion of the pilot fuel nozzle and the recirculation of the secondary air into the primary zone.

scholarly journals Effects on NOx and SO2 Emissions during Co-Firing of Coal With Woody Biomass in Air Staging and Reburning

2018 ◽  
Vol 7 (1) ◽  
pp. 1 ◽  
Author(s):  
Nihad Hodžić ◽  
Sadjit Metović ◽  
Anes Kazagic
Keyword(s):  
Combustion Chamber ◽  
Power Plants ◽  
Thermal Power ◽  
Woody Biomass ◽  
Flue Gases ◽  
Simultaneous Application ◽  
Positive Effects ◽  
Conventional Combustion ◽  
The Impact ◽  
Air Staging

Co-firing coal with different types of biomass is increasingly being applied in thermal power plants in Europe. The main motive for the use of biomass as the second fuel in coal-fired power plants is the reduction of CO2 emissions, and related financial benefits in accordance with the relevant international regulations and agreements. Likewise, the application of primary measures in the combustion chamber, which also includes air staging and/or reburning, results in a significant reduction in emission of polluting components of flue gases, in particular NOx emissions. In addition to being efficient and their application to new and future thermoblocks is practically unavoidable, their application and existing conventional combustion chamber does not require significant constructional interventions and is therefore relatively inexpensive. In this work results of experimental research of co-firing coals from Middle Bosnian basin with waste woody biomass are presented. Previously formed fuel test matrix is subjected to pulverized combustion under various temperatures and various technical and technological conditions. First of all it refers to the different mass ratio of fuel components in the mixture, the overall coefficient of excess air and to the application of air staging and/or reburning. Analysis of the emissions of components of the flue gases are presented and discussed. The impact of fuel composition and process temperature on the values of the emissions of components of the flue gas is determined. Additionally, it is shown that other primary measures in the combustion chamber are resulting in more or less positive effects in terms of reducing emissions of certain components of the flue gases into the environment. Thus, for example, the emission of NOx of 989 mg/ measured in conventional combustion, with the simultaneous application of air staging and reburning is reduced to 782 mg/, or by about 21%. The effects of the primary measures applied in the combustion chamber are compared and quantified with regard to conventional combustion of coals from Middle Bosnian basin.Article History: Received: November 5th 2017; Revised: Januari 6th 2018; Accepted: February 1st 2018; Available onlineHow to Cite This Article: Hodžić, N., Kazagić, A., and Metović, S. (2018) Experimental Investigation of Co-Firing of Coal with Woody Biomass in Air Staging and Reburning. International Journal of Renewable Energy Development, 7(1), 1-6.https://doi.org/10.14710/ijred.7.1.1-6

scholarly journals Alternative Options for Modernization of Regional Heat Supply Systems: Environmental and Economic Aspects

2021 ◽  
Vol 31 (3) ◽  
pp. 407-415
Author(s):  
Darya Bergen
Keyword(s):  
Russian Federation ◽  
Heat Supply ◽  
Power Plants ◽  
Alternative Fuels ◽  
Thermal Power ◽  
Alternative Fuel ◽  
Solid Biofuel ◽  
The Russian Federation ◽  
Heat Supply Systems ◽  
Supply Systems

At present, environmental pollution by fuel combustion products is one of the key problems in the heat supply sector. It affects the entire population of the Earth. The purpose of the research is to substantiate the necessity of ecological upgrading of thermal power facilities in the Irkutsk region and using a part of municipal solid waste as an alternative fuel at thermal power facilities of the Russian Federation. The research shows that the use of the two kinds of fuel (solid biofuel and alternative fuel) can reduce the anthropogenic load. This measure can be a way of energy efficient disposal of accumulated and annually generated production and consumer waste. The transition to alternative fuels can be most efficiently implemented in boiler houses. This is due to lower capital investments in the modernization of boiler houses as compared to the modernization of thermal power plants. The calculations in the article confirm that the implementation of environmental modernization of regional heat supply systems is not economically beneficial for entrepreneurs. The state should supplement the methods of regulation with targeted co-financing of programs for the modernization of thermal power facilities in order to accelerate the processes of modernization of heat supply in the Russian Federation. At the same time, the recipients of support must comply with the established indicators further on.

scholarly journals On Line Dirt Based Soot Blowing System using Fuzzy Logic for Utility Boilers

2019 ◽  
Vol 8 (2) ◽  
pp. 1669-1671
Keyword(s):  
Power Plants ◽  
Intelligent System ◽  
Thermal Power ◽  
Heating Surface ◽  
Boiler Tube ◽  
Heating Efficiency ◽  
Utility Boilers ◽  
On Line ◽  
Simulation Results ◽  
Burning Coal

Soot is a byproduct of burning coal in thermal power plants. The soot accumulates in the boilers tubes. It gradually spoils the heating surface which reduces the heating efficiency. Hence it has to be cleaned. This process is called soot blowing. The existing soot blower control system in the old boiler is composed of relays, timers and contactors which are not efficient. In order to improve the efficiency, an intelligent system is proposed which estimates the dirt in the boiler tube periodically and initiates soot blowing process to improve the thermal efficiency. Simulation results demonstrate the superiority of the proposed scheme when compared to relay logics.

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