Numerical Simulation of Heavy Fuel Oil Combustion Characteristics and NOx Emissions in Calciner in Cement Industry

2015 ◽  
Author(s):  
Hisham Aboelsaod ◽  
Essam E. Khalil
Keyword(s):  
Molecular Nitrogen ◽  
Combustion Characteristics ◽  
Cement Industry ◽  
Operating Conditions ◽  
Fuel Oil ◽  
Combustion Model ◽  
Injection Velocity ◽  
Nox Emissions ◽  
Heavy Fuel Oil ◽  
Swirl Number

The aim of the present study is to numerically investigate the combustion characteristics of Heavy Fuel Oil (HFO) and NOx emissions inside a calciner used in cement industry. The calciner is a furnace placed before the rotary Kiln its main objectives are the reduction of CO2 emissions and air pollutions while enhancing the cement quality through separating the calcination and clinkering processes. In order to conduct the present investigations the calciner at CEMEX Egypt Cement Company was considered and real dimensions and operating conditions were applied. The combustion model was based on the conserved scalar (mixture fraction) and prescribed Probability Density Function (PDF) approach. The (RNG) k-ε turbulence model has been used. The HFO droplet trajectories were predicted by solving the momentum equations for the droplets using Lagrangian treatment. The radiation heat transfer equation was solved using P1 method. The formation of thermal NOx from molecular nitrogen was modeled according to the extended Zeldovich mechanism. The effects of varying the burner’s swirl number and viscosity grade on the combustion performance of HFO and the resulting NOx emissions were considered. The burner’s swirl number influences the mixing rate of air and fuel. A small swirl number ≤ 0.6 is not desired as it elongates the flame; increases flue gases temperatures and increases the NOx emissions inside the calciner. A swirl number ≥ 0.6 is found optimal for good combustion characteristics and NOx emissions concentration. Meanwhile, it was found that the HFO viscosity has a significant effect on the injection velocity and must be considered as a function of temperature during the analysis as this will significantly affects the combustion characteristics.

Numerical Simulation of Heavy Fuel Oil Combustion Characteristics and NOx Emissions in Calciner in Cement Industry

2015 ◽  
Author(s):  
Hisham Abou ElSoad ◽  
Essam E. Khalil
Keyword(s):  
Mixture Fraction ◽  
Radiation Heat Transfer ◽  
Combustion Characteristics ◽  
Cement Industry ◽  
Fuel Oil ◽  
Combustion Model ◽  
Injection Velocity ◽  
Nox Emissions ◽  
Heavy Fuel Oil ◽  
Probability Density Function Pdf

The aim of the present study is to numerically investigate the combustion characteristics of Heavy Fuel Oil (HFO) and NOx emissions inside a Calciner used in cement industry. The combustion model was based on the conserved scalar (mixture fraction) and prescribed Probability Density Function (PDF) approach. The (RNG) k-ε turbulence model has been used. The HFO droplet trajectories were predicted by solving the momentum equations for the droplets using Lagrangian treatment. The radiation heat transfer equation was solved using P1 method. A swirl number greater than 0.6 was found to be optimal for good combustion characteristics and NOx emissions concentration. Meanwhile, it was found that the HFO viscosity value assumption has a significant effect on the injection velocity and must be considered as a function of temperature during the analysis as this will significantly affect the combustion characteristics.

Combustion Characteristics of Small Size Gas Turbine Combustor Fueled by Biomass Gas Employing Flameless Combustion

2007 ◽  
Author(s):  
Masato Hiramatsu ◽  
Yoshifumi Nakashima ◽  
Sadamasa Adachi ◽  
Yudai Yamasaki ◽  
Shigehiko Kaneko
Keyword(s):  
Gas Turbine ◽  
Combustion Efficiency ◽  
Combustion Characteristics ◽  
Operating Conditions ◽  
Nox Emissions ◽  
Gas Turbine Combustor ◽  
Flameless Combustion ◽  
Engine Exhaust ◽  
Micro Gas Turbine

One approach to achieving 99% combustion efficiency (C.E.) and 10 ppmV or lower NOx (at 15%O2) in a micro gas turbine (MGT) combustor fueled by biomass gas at a variety of operating conditions is with the use of flameless combustion (FLC). This paper compares experimentally obtained results and CHEMKIN analysis conducted for the developed combustor. As a result, increase the number of stage of FLC combustion enlarges the MGT operation range with low-NOx emissions and high-C.E. The composition of fuel has a small effect on the characteristics of ignition in FLC. In addition, NOx in the engine exhaust is reduced by higher levels of CO2 in the fuel.

Careful Parameter Study to Enhance the Effect of Injecting Heavy Fuel Oil Into a Crossflow Using Numerical Approaches

2018 ◽  
Author(s):  
Masoud Darbandi ◽  
Ali Fatin ◽  
Gerry E. Schneider
Keyword(s):  
Flow Velocity ◽  
Cross Flow ◽  
Droplet Breakup ◽  
Computational Method ◽  
Fuel Oil ◽  
Injection Velocity ◽  
Parameter Study ◽  
Spray Parameters ◽  
Heavy Fuel Oil ◽  
Spray Characteristics

The flow and spray parameters can have noticeable roles in heavy fuel oil (HFO) spray finesse. As known, the interaction between droplets and cross flow should be considered carefully in many different industrial applications such as the process burners and gas turbine combustors. So, it would be so important to investigate the effect of injecting HFO into a crossflow more subtly. In this work, the effects of various flow and spray parameters on the droplet breakup and dispersion parameters are investigated numerically using the finite-volume-element method. The numerical method consists of a number of different models to predict the droplets breakup and their dispersion into a cross flow including the spray-turbulence interaction one. An Eulerian–Lagrangian approach, which suitably models the interaction between the droplets and turbulence, and also models the droplets secondary breakup is used to investigate the interactions between the flow and the droplet behaviors. After validating the computational method via comparing them with the data provided by the past researches, four test cases with varying swirl number, air axial velocity, droplet size, and fuel injection velocity are examined to find out the effects of preceding parameters on some spray characteristics including the droplets path, sauter mean diameter (SMD), and dispersed phase mass concentration. The results show that the droplets inertia and the flow velocity magnitude have significant effects on spray characteristics. As the droplets become more massive, the deflection of spray in flow direction becomes less. Also, increasing of flow velocity causes more deflection for sprays with the same droplet sizes.

Impacts of Dilution on Hydrogen Combustion Characteristics and NOx Emissions

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
P. R. Resende ◽  
Alexandre Afonso ◽  
Carlos Pinho ◽  
Mohsen Ayoobi
Keyword(s):  
Flame Stabilization ◽  
Combustion Characteristics ◽  
Operating Conditions ◽  
Nox Emissions ◽  
Detailed Chemical Kinetics ◽  
Portable Power ◽  
Small Scales ◽  
Potential Applications ◽  
Flame Behavior ◽  
Detailed Chemical

Combustion characteristics at small scales have been studied continuously due to the potential applications in portable power devices. It is known that heat release impacts at small scales result in different flame behavior as compared to conventional scales. The impacts of geometry, stoichiometry, flow rates, wall temperatures, etc., are widely studied in the literature. However, dilution impacts still need to be further studied due to its important role on controlling the flame behavior and subsequent pollutants emissions at these scales. In this work, premixed hydrogen/air combustion is simulated at an axis-symmetric microchannel (with diameter D = 0.8 mm and length L = 10 mm), where detailed chemical kinetics are implemented in simulations (32 species and 173 reactions). The heat transfer on the wall is considered by imposing a hyperbolic temperature profile on the wall, where the wall temperature increases from 300 K at the inlet to 1300 K at the outlet. With this setup, a range of equivalence ratios including a typical fuel-lean regime (ϕ = 0.7), stoichiometric regime (ϕ = 1.0), and two cases at an ultra-rich regime (ϕ = 2.0 and ϕ = 3.0) are investigated. For each equivalence ratio, excess dilution (using N2) is introduced to the mixture, and its impact is compared with other cases. With that, the impacts of dilution variations on the combustion characteristics of premixed hydrogen/air are investigated for different equivalence ratios. More specifically, several incidents such as flame dynamics, flame stabilization, extinctions, and NOx emissions are studied for the aforementioned operating conditions.

Numerical Investigations of NOx Emissions of a Partially Premixed Burner for Natural Gas Operations in Industrial Gas Turbine

2014 ◽  
Author(s):  
Alessandro Innocenti ◽  
Antonio Andreini ◽  
Andrea Giusti ◽  
Bruno Facchini ◽  
Matteo Cerutti ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Turbulent Combustion ◽  
Fuel Injection ◽  
Formation Rate ◽  
Operating Conditions ◽  
Combustion Model ◽  
Nox Emissions ◽  
Air Concentration ◽  
Partially Premixed ◽  
Industrial Gas Turbine

In the present paper a numerical analysis of a low NOx partially premixed burner for industrial gas turbine applications is presented. The first part of the work is focused on the study of the premixing process inside the burner. Standard RANS CFD approach was used: k–ε turbulence model was modified and calibrated in order to find a configuration able to fit available experimental profiles of fuel/air concentration at the exit of the burner. The resulting profiles at different test points have been used to perform reactive simulations of an experimental test rig, where exhaust NOx emissions were measured. An assessment of the turbulent combustion model was carried out with a critical investigation of the expected turbulent combustion regimes in the system and taking into account the partially premixed nature of the flame due to the presence of diffusion type pilot flames. A reliable numerical setup was discovered by comparing predicted and measured NOx emissions at different operating conditions and at different split ratio between main and pilot fuel. In the investigated range, the influence of the premixer in the NOx formation rate was found to be marginal if compared with the pilot flame one. The calibrated numerical setup was then employed to explore possible modifications to fuel injection criteria and fuel split, with the aim of minimizing exhaust NOx emissions. This preliminary numerical screening of alternative fuel injection strategies allowed to define a set of advanced configurations to be investigated in future experimental tests.

Effect of Chemical Fuel Additives on Liquid Fuel Saving, and Emissions for Heavy Fuel Oil

2016 ◽  
Author(s):  
Ahmed Emara
Keyword(s):  
Mass Flow ◽  
Acoustic Noise ◽  
Combustion Process ◽  
Combustion Characteristics ◽  
Fuel Oil ◽  
Mass Spectrometry Analysis ◽  
Fuel Additive ◽  
Fuel Saving ◽  
Fuel Additives ◽  
Heavy Fuel Oil

As fossil fuel resources are considered non-renewable sources of fuel, they will be totally consumed in the near or far future. Due to the intensive and extensive consumption of these fossil fuels in all life sectors such as transportation, power generation, industrial processes, and residential consumption, it is important to find other new methods to cover this fuel demand. Fuel additives are chemicals used to enhance fuel combustion performance, save fuel amounts required for combustion, and correct deficiencies in power and efficiency during consumption. The fuel additives are blended with the traditional fuel even by parts per million range for controlling chemical contaminants and emission reduction. In the present work, the experimental measurements were done, to evaluate the effect of fuel additive blending with the raw heavy fuel oil (Mazut) on fuel saving which is of a great significance, emissions control, and combustion characteristics as well as the combustion efficiency. These measurements are as follows: initial temperature of Mazut, exhaust gas temperature at the end of combustor, air and fuel mass flow rates to determine the heat load, inlet and outlet temperatures of cooling water, mass flow rate of water, concentration of different exhaust gases, acoustic (noise level) measurements, smoke number, and flame length. These measurements are performed using swirled vanes, co-axial, and double heavy fuel nozzle (1.5 gal/hr for each one) burner with maximum heating load of 550 kW. GC-MS (Gas chromatography-mass spectrometry) analysis was performed by using Hewlett Packard model 5890 equipped with a flame ionization detector (FID) to identify the fuel additives substances within the tested samples. The results reveal that the use of fuel additives improves the combustion characteristics and play an important role in fuel saving as well as emission and combustion process.

Study on the Relationship Between Combustion Characteristics and Properties of Marine Heavy Fuel Oil

2003 ◽  
Author(s):  
Takaaki Hashimoto ◽  
Senichi Sasaki
Keyword(s):  
Ignition Delay ◽  
Average Molecular Weight ◽  
Poor Quality ◽  
Combustion Characteristics ◽  
Carbon Residue ◽  
Fuel Oil ◽  
Heavy Fuel Oil ◽  
Marine Fuel ◽  
Fuel Oils ◽  
Flame Retardation

The combustion characteristics (ignition delay and combustion period in this paper) of marine heavy fuel oil are affected by many factors such as density, carbon residue, asphaltene, aromaticity and carbon/hydrogen (C/H) ratio. When investigating the causes of operational problems in diesel engines, what properties should we check to find whether the main causes of the problems are related to fuel oil or not? What is the threshold of ignition delay and combustion period of fuel oil? The authors studied these topics using a combustion test apparatus called FIA 100, and arrived at the following conclusions: 1. The aromaticity index (CCAI) and the C/H ratio have good correlation with the combustion characteristics of marine fuel oil. These factors cannot be ignored during troubleshooting. 2. The carbon residue and asphaltene in fuel oil have no correlation with ignition delay, but have some correlation with the combustion period. 3. There is practically no correlation between the average molecular weight of fuel oil, and both ignition delay and combustion period. 4. Tentative threshold values of ignition delay and combustion period can be set for fuel oils of poor quality (flame retardation).

A Study on Biodiesel NOx Emission Control With the Reduced Chemical Kinetics Model

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Juncheng Li ◽  
Zhiyu Han ◽  
Cai Shen ◽  
Chia-fon Lee
Keyword(s):  
Chemical Kinetics ◽  
Combustion Process ◽  
Operating Conditions ◽  
Nox Emission ◽  
Kinetics Model ◽  
Combustion Model ◽  
Nox Emissions ◽  
Soot Emission ◽  
Start Of Injection ◽  
Combustion Processes

In this paper, the effects of the start of injection (SOI) timing and exhaust gas recirculation (EGR) rate on the nitrogen oxides (NOx) emissions of a biodiesel-powered diesel engine are studied with computational fluid dynamics (CFD) coupling with a chemical kinetics model. The KIVA code coupling with a CHEMKIN-II chemistry solver is applied to the simulation of the in-cylinder combustion process. A surrogate biodiesel mechanism consisting of two fuel components is employed as the combustion model of soybean biodiesel. The in-cylinder combustion processes of the cases with four injection timings and three EGR rates are simulated. The simulation results show that the calculated NOx emissions of the cases with default EGR rate are reduced by 20.3% and 32.9% when the injection timings are delayed by 2- and 4-deg crank angle, respectively. The calculated NOx emissions of the cases with 24.0% and 28.0% EGR are reduced by 38.4% and 62.8%, respectively, compared to that of the case with default SOI and 19.2% EGR. But higher EGR rate deteriorates the soot emission. When EGR rate is 28.0% and SOI is advanced by 2 deg, the NOx emission is reduced by 55.1% and soot emission is controlled as that of the case with 24% EGR and default SOI. The NOx emissions of biodiesel combustion can be effectively improved by SOI retardation or increasing EGR rate. Under the studied engine operating conditions, introducing more 4.8% EGR into the intake air with unchanged SOI is more effective for NOx emission controlling than that of 4-deg SOI retardation with default EGR rate.

Accurate prediction of the rate of heat release in a modern direct injection diesel engine

2002 ◽  
Vol 216 (8) ◽  
pp. 663-675 ◽  
Author(s):  
P A Lakshminarayanan ◽  
Y V Aghav ◽  
A D Dani ◽  
P S Mehta
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Direct Injection ◽  
Turbulent Energy ◽  
Operating Conditions ◽  
Combustion Model ◽  
Injection Velocity ◽  
Mixing Rate ◽  
Di Diesel Engine ◽  
Rate Of Heat Release

An accurate model for the heat release rate in a modern direct injection (DI) diesel engine is newly evolved from the known mixing controlled combustion model. The combustion rate could be precisely described by relating the mixing rate to the turbulent energy created at the exit of the nozzle as a function of the injection velocity and by considering the dissipation of energy in free air and along the wall. The complete absence of tuning constants distinguishes the model from the other zero-dimensional or pseudomultidimensional models, at the same time retaining the simplicity. Successful prediction of the history of heat release in engines widely varying in bores, rated speeds and types of aspirations, at all operating conditions, validated the model.

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