scholarly journals Decreasing NOx Emissions by Way of the Staged Fuel Combustion

2021 ◽  
pp. 18-23
Author(s):  
Maksym Lohvyniuk ◽  
Yevhen Novakivskyy
Keyword(s):  
Nitrogen Oxides ◽  
Scientific Paper ◽  
Fuel Combustion ◽  
Ecological Indices ◽  
Air Concentration ◽  
Boiler Furnace ◽  
Air Supply ◽  
Standard Values ◽  
Gas Recirculation ◽  
The Mathematical Model

The purpose of this scientific paper was to analyze the mathematical model built for the staged arrangement of the fuel combustion system and calculate the formation of nitrogen oxides throughout the boiler furnace height for the different distributions of thermal loadings along the full vertical extent of the combustion chamber. The obtained results enable the determination of the overall amount of nitrogen oxides formed in the boiler and it allows us to provide appropriate ecological indices for the boiler when regulating the air concentration in the burner rows. In practice, to suppress the formation of nitrogen oxides we often use such basic methods as low-toxic burners, staged fuel combustion, flue gas recirculation, etc. The analysis of the computations done allows us to draw a conclusion that the operation of the boiler with ecological indices that satisfy standard values of the European Directive 2010/75/EU is only possible for the load below 40 %. After reconstruction of the burner system and adjustment of the air supply system with the observation of above ecological norms the boiler power can be increased up to 80 % using the staged fuel burning with the ensurance of environmental performances during its operation. Computational and experimental data errors varied in the range of 8 % to 12 %. With the increase in the overall chemical incomplete combustion by 40 % to 60 % (q3) these losses are compensated by a decrease in absolute losses due to the boiler aggregate load and the losses through external walls (q5) due to an increase in the boiler power.

scholarly journals Gas Recirculation Impact on the Nitrogen Oxides Formation in the Boiler Furnace

2016 ◽  
Vol 152 ◽  
pp. 434-438 ◽  
Author(s):  
V.V. Shalaj ◽  
A.G. Mikhajlov ◽  
E.E. Novikova ◽  
S.V. Terebilov ◽  
T.V. Novikova
Keyword(s):  
Nitrogen Oxides ◽  
Boiler Furnace ◽  
Gas Recirculation

WET BURNING – THE MODERN TREND IN ENVIRONMENTAL BENIGN FUEL COMBUSTION AND IN SOLUTION TO THE PROBLEM OF SUSTAINABLE DEVELOPMENT OF THE POWER GENERATION

2018 ◽  
pp. 96-117 ◽  
Author(s):  
B. S. Soroka
Keyword(s):  
Numerical Simulation ◽  
Nitrogen Oxides ◽  
Chemical Kinetics ◽  
Fuel Combustion ◽  
Transport Processes ◽  
Cfd Modeling ◽  
Furnace Chamber ◽  
Modern Trend ◽  
Atmospheric Air ◽  
No Formation

The article considers the role and place of water and water vapor in combustion processes with the purpose of reduction the effluents of nitrogen oxides and carbon oxide. We have carried out the complex of theoretical and computational researches on reduction of harmful nitrogen and carbon oxides by gas fuel combustion in dependence on humidity of atmospheric air by two approaches: CFD modeling with attraction of DRM 19 chemical kinetics mechanism of combustion for 19 components along with Bowman’s mechanism used as “postprocessor” to determine the [NO] concentration; different thermodynamic models of predicting the nitrogen oxides NO formation. The numerical simulation of the transport processes for momentum, mass and heat being solved simultaneously in the united equations’ system with the chemical kinetics equations in frame of GRI methane combustion mechanism and NO formation calculated afterwards as “postprocessor” allow calculating the absolute actual [CO] and [NO] concentrations in dependence on combustion operative conditions and on design of furnace facilities. Prediction in frame of thermodynamic equilibrium state for combustion products ensures only evaluation of the relative value of [NO] concentration by wet combustion the gas with humid air regarding that in case of dry air – oxidant. We have developed the methodology and have revealed the results of numerical simulation of impact of the relative humidity of atmospheric air on harmful gases formation. Range of relative air humidity under calculations of atmospheric air under impact on [NO] and [CO] concentrations at the furnace chamber exit makes φ = 0 – 100%. The results of CFD modeling have been verified both by author’s experimental data and due comparing with the trends stated in world literature. We have carried out the complex of the experimental investigations regarding atmospheric air humidification impact on flame structure and environmental characteristics at natural gas combustion with premixed flame formation in open air. The article also proposes the methodology for evaluation of the nitrogen oxides formation in dependence on moisture content of burning mixture. The results of measurements have been used for verification the calculation data. Coincidence of relative change the NO (NOx) yield due humidification the combustion air revealed by means of CFD prediction has confirmed the qualitative and the quantitative correspondence of physical and chemical kinetics mechanisms and the CFD modeling procedures with the processes to be studied. A sharp, more than an order of reduction in NO emissions and simultaneously approximately a two-fold decrease in the CO concentration during combustion of the methane-air mixture under conditions of humidification of the combustion air to a saturation state at a temperature of 325 K.

Characteristics and flame appearance of oxy-fuel combustion using flue gas recirculation

Fuel ◽  
2021 ◽  
Vol 297 ◽  
pp. 120775
Author(s):  
Mohsen Abdelaal ◽  
Medhat El-Riedy ◽  
Ahmed M. El-Nahas ◽  
Fathy R. El-Wahsh
Keyword(s):  
Flue Gas ◽  
Fuel Combustion ◽  
Flue Gas Recirculation ◽  
Gas Recirculation

SPECTRAL DIAGNOSTICS OF THE HYDROCARBON FUEL COMBUSTION PROCESS

2021 ◽  
pp. 12-17
Author(s):  
M. A. Vaganov
Keyword(s):  
Combustion Process ◽  
Hydrocarbon Fuel ◽  
Combustion Products ◽  
Combustible Mixture ◽  
Fuel Combustion ◽  
Propane Combustion ◽  
Gaseous Hydrocarbon ◽  
Spectral Bands ◽  
Air Supply ◽  
Spectral Diagnostics

It is proposed to use the methods of applied optical spectroscopy to solve the problem of control and diagnostics of gaseous hydrocarbon fuel combustion in this work. The results of an experimental study of spectroscopic informative parameters characterizing the propane combustion process are presented for three modes: combustion of pure propane without air supply, stoichiometric combustion and combustion with a change in the amount of supplied air relative to stoichiometric combustion. As a result of the experiment, it was found that the most intense bands in the emission spectrum of the flame arising from the combustion of propane correspond to the spectral bands of radicals of combustion products: OH, CH, and C2. While the intensities of various systems of bands in the flame spectrum depend significantly on the composition of the combustible mixture.

scholarly journals Ensuring Requirements for Emissions of Harmful Substances of Diesel Engines

2020 ◽  
Vol 19 (4) ◽  
pp. 305-310
Author(s):  
G. M. Kuharonak ◽  
D. V. Kapskiy ◽  
V. I. Berezun
Keyword(s):  
Diesel Engine ◽  
Nitrogen Oxides ◽  
Fuel Consumption ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Average Temperature ◽  
Dispersed Particles ◽  
Harmful Substances ◽  
Gas Recirculation ◽  
Emissions Of Harmful Substances

The purpose of this work is to consider the requirements for emissions of harmful substances of diesel engines by selecting design and adjustment parameters that determine the organization of the workflow, and the exhaust gas cleaning system, taking into account the reduction of fuel consumption. Design elements and geometric characteristics of structures for a turbocharged diesel engine of Д-245 series produced by JSC HMC Minsk Motor Plant (4ЧН11/12.5) with a capacity of 90 kW equipped with an electronically controlled battery fuel injection have been developed: exhaust gas recirculation along the high pressure circuit, shape and dimensions of the combustion chamber, the number and angular arrangement of the nozzle openings in a nozzle atomizer, and inlet channels of the cylinder head. Methods for organizing a workflow are proposed that take into account the shape of the indicator diagrams and affect the emissions of nitrogen oxides and dispersed particles differently. Their implementation allows us to determine the boundary ranges of changes in the control parameters of the fuel supply and exhaust gas recirculation systems when determining the area of minimizing the specific effective fuel consumption and the range of studies for the environmental performance of a diesel engine. The paper presents results of the study on the ways to meet  the requirements for emissions of harmful substances, obtained by considering options for the organization of working processes, taking into account the reduction in specific effective fuel consumption, changes in the average temperature of the exhaust gases and diesel equipment. To evaluate these methods, the following indicators have been identified: changes in specific fuel consumption and average temperature of the toxicity cycle relative to the base cycle, the necessary degree of conversion of the purification system for dispersed particles and NOx. Recommendations are given on choosing a diesel engine to meet Stage 4 emission standards for nitrogen oxides and dispersed particles.

scholarly journals ЗМЕНШЕННЯ ВИКИДІВ СУДНОВОГО ДИЗЕЛЯ УТИЛІЗАЦІЄЮ ТЕПЛОТИ РЕЦИРКУЛЯЦІЙНИХ ГАЗІВ ЕЖЕКТОРНОЮ ХОЛОДИЛЬНОЮ МАШИНОЮ

2019 ◽  
pp. 20-24
Author(s):  
Максим Андрійович Пирисунько ◽  
Роман Миколайович Радченко ◽  
Андрій Адольфович Андреєв ◽  
Вікторія Сергіївна Корнієнко
Keyword(s):  
Nitrogen Oxides ◽  
Alternative Fuels ◽  
Exhaust Gas ◽  
Exhaust Gases ◽  
Harmful Emissions ◽  
Harmful Substances ◽  
Main Engine ◽  
Gas Recirculation ◽  
Refrigeration Machine ◽  
Emissions Of Harmful Substances

The problem of air basin pollution of the World Ocean with harmful emissions from the exhaust gases of marine diesel engines is primarily associated with the creation of highly efficient technologies for the neutralization of nitrogen oxides NOx on exhaust gases from a diesel engine. Emissions of harmful substances from the combustion of marine fuels are limited by international atmospheric protection programs and the requirements of the International Maritime Organization (IMO). The requirements relate to almost all groups of harmful emissions in marine engines and the more stringent of them are primarily related to nitrogen oxides NOx and sulfur oxides SOx. To reduce harmful emissions from exhaust gases into the environment, scientists and world engine leaders use and suggest various methods for reducing the content of harmful substances in exhaust gases. The implementation of new standards in the areas of further improvement of the working process, the use of alternative fuels, fuel, and air additives, as well as selective catalytic reduction systems do not preclude further development of scientific research in the field of exhaust gas cleaning. One of the promising ways in environmentalizing marine internal combustion engines is the neutralization of harmful substances in exhaust gases through particular gas recirculation (EGR-technology). However, the use of such techniques conflicts with the engine's energy efficiency. In the work presented, the scheme-design solution of the exhaust gas recirculation system with using the heat of recirculation gases by an ejector refrigeration machine for cooling the air at the intake of ship's main engine is proposed. The effect of using the heat of recirculation gases for cooling the air at the intake of the engine is analyzed taking into account the changing climatic conditions for a particular vessel's route line. It is shown that the use of an ejector refrigeration machine reduces the air temperature at the entrance of the main engine by 5…15 ° С, which reduces the specific fuel consumption. This reduces emissions of harmful substances when the engine is running with recirculation of gases.

Emission reduction through internal and low-pressure loop exhaust gas recirculation configuration with negative valve overlap and late intake valve closing strategy in a compression ignition engine

2017 ◽  
Vol 18 (10) ◽  
pp. 973-990 ◽  
Author(s):  
Jaeheun Kim ◽  
Choongsik Bae
Keyword(s):  
High Pressure ◽  
Nitrogen Oxides ◽  
Exhaust Gas Recirculation ◽  
Low Pressure ◽  
Exhaust Gas ◽  
Effective Pressure ◽  
Intake Valve ◽  
Trade Off ◽  
Indicated Mean Effective Pressure ◽  
Gas Recirculation

An investigation was carried out to examine the feasibility of replacing the conventional high-pressure loop/low-pressure loop exhaust gas recirculation with a combination of internal and low-pressure loop exhaust gas recirculation. The main objective of this alternative exhaust gas recirculation path configuration is to extend the limits of the late intake valve closing strategy, without the concern of backpressure caused by the high-pressure loop exhaust gas recirculation. The late intake valve closing strategy improved the conventional trade-off relation between nitrogen oxides and smoke emissions. The gross indicated mean effective pressure was maintained at a similar level, as long as the intake boosting pressure kept changing with respect to the intake valve closing timing. Applying the high-pressure loop exhaust gas recirculation in the boosted conditions yielded concern of the exhaust backpressure increase. The presence of high-pressure loop exhaust gas recirculation limited further intake valve closing retardation when the negative effect of increased pumping work cancelled out the positive effect of improving the emissions’ trade-off. Replacing high-pressure loop exhaust gas recirculation with internal exhaust gas recirculation reduced the burden of such exhaust backpressure and the pumping loss. However, a simple feasibility analysis indicated that a high-efficiency turbocharger was required to make the pumping work close to zero. The internal exhaust gas recirculation strategy was able to control the nitrogen oxides emissions at a low level with much lower O2 concentration, even though the initial in-cylinder temperature was high due to hot residual gas. Retardation of intake valve closing timing and intake boosting contributed to increasing the charge density; therefore, the smoke emission reduced due to the higher air–fuel ratio value exceeding 25. The combination of internal and low pressure loop loop exhaust gas recirculation with late intake valve closing strategy exhibited an improvement on the trade-off relation between nitrogen oxides and smoke emissions, while maintaining the gross indicated mean effective pressure at a comparable level with that of the high-pressure loop exhaust gas recirculation configuration.

On the instability of ventilated cavities

1966 ◽  
Vol 26 (3) ◽  
pp. 437-457 ◽  
Author(s):  
L. C. Woods
Keyword(s):  
Pressure Fluctuations ◽  
Unsteady Motion ◽  
Cavitation Number ◽  
The Body ◽  
Supply Rate ◽  
Velocity Fluctuations ◽  
Air Supply ◽  
Resonance Frequencies ◽  
Axis Of Symmetry ◽  
The Mathematical Model

It has been found that ventilated cavities extending behind hydrofoils, plates, and other two-dimensional bodies, oscillate when the air supply rate is sufficient to reduce the cavitation number to about one-fifth of its natural value. As the rate increases further, higher modes of oscillation occur in which the cavity–water interface supports several waves that are convected downstream towards the wake, which, owing to a pinching-off action replacing the usual entrainment sink, consists of a sequence of large bubbles drifting downstream. A theory of such flows that allows both for the convected velocity fluctuations in the cavity, and for the transport of bubble volume down the wake, is given in this paper. Coupled with a rather simple phenomenological relation between the pressure fluctuations within the cavity and the departure of the pinched-off rear portion of the cavity—explained in terms of the action of the re-entrant jet—this theory successfully predicts the resonance frequencies obtained in experiments by Silberman & Song.The theory also provides a solution of the more general problem of determining the fluctuations in the pressure distribution over the whole surface of the body, when it is in a prescribed unsteady motion along its axis of symmetry (the theory is confined to symmetrical bodies and flows). Thus the growth in drag due to a sudden increment in the upstream velocity can be predicted, and also the damping forces acting on the body when it is forced to oscillate at a given frequency. It is shown that in all cases the body is unstable.One important feature of the mathematical model chosen is that it completely avoids the presence of a time-dependent sink at infinity—with its associated infinite pressures—by conserving total volume of wake and cavity in just the same way as vorticity is conserved in unsteady aerofoil theory.

Sign in / Sign up

Export Citation Format

Share Document