Pilot Burner Research Articles

Effect of fuel temperature on the structure of a high-pressure liquid-fueled swirl flame

Experiments were conducted in a liquid-fueled, piloted swirl burner operating at high pressure (1.0 MPa and 2.0 MPa) to study the influence of fuel injection temperature on the coupled flow and combustion processes. Simultaneous 10 kHz stereoscopic particle image velocimetry and OH* chemiluminescence measurements were used to characterize the overall flow and flame structure over a range of equivalence ratios at three discrete fuel temperatures: 367, 486, and 577 K. The location of the pilot flame was found to be insensitive to the fuel temperature, while the main flame moved closer to the injector as the fuel temperature was increased. This was accompanied by an increase in the axial velocity in the region of the main flame and a downstream shift of the shear layer along the border of the central recirculation zone. Analysis of the mean velocity fields relative to the location of maximum OH* chemiluminescence intensity showed an increase in velocity normal to the mean flame position with higher fuel temperatures. This indicates the flame speed increases with fuel temperature, which, along with the changes to the fuel injection process, helps explain the observed changes to the flow and flame structure.

Experimental Study on the Fire Property of Pure Polymers and Polymer Mixture Pellets

The present study conducted a series of fire tests using a cone calorimeter to understand the effects of pure polymers and polymer mixtures on fire properties. An initial fuel mass of 50 g in a 10-cm-diameter pan was placed on the load cell. Polystyrene, polyethylene, polymethylmethacrylate, polystyrene-polyethylene mixture, and polystyrene-polymethylmethacrylate mixture was used as fuel. The fuel ignited using a pilot burner was allowed to burn freely. The fire properties of polymer mixtures, such as the mass loss rate, the effective heat of combustion, the CO yield rate, and the soot yield rate, did not depend on the mixture composition or fuel types, suggesting it is difficult to apply the statistically representative values of fire properties of the mixture. Therefore, quantitative measurements based on experiments and their database are necessary for reasonable fire analysis.

Calculation and analysis of the flamelet library for numerical modelling of the non-premixed combustion of natural gas in a pilot burner

The flamelet modelling concept has been employed for numerical simulation of the non-premixed combustion of natural gas in a pilot burner of novel type. This prospective laboratory-scale burner device is featured by axial supply of high-speed jet of flue gases, while the fuel (natural gas) and the oxidizer (air) are supplied radially and separately inside the burner chamber. With the use of chemical kinetics mechanism for natural gas (62 species, 398 reactions) the flamelet library has been generated, from its analysis the flame quenching has been determined at the scalar dissipation rate limit of 42 (1/s). From this library the lookup-table of thermochemical solution has been pre-calculated with the presumed beta-function pdf averaging. On this basis the numerical simulation of aerodynamics, heat transfer and the natural gas combustion processes, including soot formation and its effect on radiative heat transfer, has been performed in the considered pilot burner run at the thermal load of 8.8 kW and air excess coefficient of 0.85 (inside the burner body). The distributions of gas species are presented. The predicted NOx emission in exhaust gases is 48.8 mg/m3 for the studied burner regime.

Optimalisasi Perawatan Sistem Auxiliary Boiler Dalam Menghasilkan Uap Panas

Auxiliary boilers that have the function of producing hot steam are auxiliary steam boilers. The function of this steam is to heat the fresh water jacket cooling and fuel, drive the turbine pump, heat the liquid in the tank and room. This study aims to optimize the maintenance of auxiliary boiler systems, especially in the auxiliary steam boilers. This research was conducted in the engine room on the MT ship. This research is a qualitative descriptive study with data collection obtained from observation, interviews and documentation. The result of this study is the implementation of maintenance of auxiliary boiler components including: Boiler water; main burner; pilot burner; blower; and pumps. Overall, the average before optimizing maintenance, the effectiveness of the implementation of the planning maintenance system in auxiliary boilers was around 58.86%, and the average increased by 27.57% so that the average after optimization of maintenance with the guidelines for planning system maintenance became 86.43%. Auxiliary boiler system maintenance steam boiler In MT Tender Harmony can run optimally so that it can produce quality steam so that it can heat the fuel optimally.

Automatized Experimental Combustor Development Using Adaptive Surrogate Model-Based Optimization

Abstract Lean premixed combustion is the state-of-the-art technology to achieve ultra low NOx emissions in stationary gas turbines. However, lean premixed flames are susceptible to thermoacoustic instabilities, lean blowout, and flashback. The design of such a combustion system is thus always related to the balancing between the levels of emissions and flame stability. Data-driven optimization methods and the adaptation of models through artificial intelligence have experienced a surge in development in the past years. The goal of this study is to show the potential of these methods for gas turbine burner development. A special pilot burner that features 61 different positions of fuel injection, manufactured by means of selective laser melting is used to modify the gas mixture close to the flame anchoring position. Each of the injector lines is equipped with an individual valve, such that the distribution of fuel-air mixture can be modified variously. Installed into an industrial MGT6000 swirl combustor, a data-driven optimization method is used to find an optimal subset of injection locations by automated experiments. The method uses a surrogate model that is based on Gaussian processes regression. It is adopted for experimental optimization, keeping measurement efforts to a minimum. The optimizer controls the fuel valves and uses live measurements to find a distribution that generates minimal NOx emissions while ensuring flame stability. The solutions found by the optimization scheme are analyzed and advantages and limitations of the approach are discussed.

3D Flame surface density measurements via orthogonal cross-planar mie scattering in a low-turbulence bunsen flame

Quasi-instantaneous Mie scattering measurements were conducted to determine the flame surface location using two orthogonal planes to obtain the 3D orientation and measurement of 3D flame surface density (FSD) on a stabilised piloted Bunsen burner with turbulence levels of 1 to 2.5 times the laminar flame speed. A double-pulsed 527 nm high-frequency laser (part of a high-frequency particle image velocimetry dual-head setup) was split into two separated laser beams through a polarizer to generate laser sheets at 3 kHz on a vertical plane and a horizontal plane. The vertical plane across the centerline of the Bunsen-stabilized flame was kept constant, whilst the height of the horizontal plane was adjusted from the base of the flame for different heights. The flame edge was defined as the location where droplet tracers disappear, and calculated based on the local change in the number density of the flame edge. Projections of the flame normal vector onto two measurement planes were used to calculate directing angles on each plane, and the 3D FSD was estimated based on the measured angles at the intersecting lines of two planes. A comparison of the 2D to 3D FSD magnitudes was made, for cases with and without mean angle corrections. The results show that the 2D FSD approximations are lower than the 3D measurements by a factor of 20–30% if uncorrected, and up to 28% after corrections.

Pilot impact on turbulent premixed methane/air and hydrogen-enriched methane/air flames in a laboratory-scale gas turbine model combustor

The impact of pilot flame operation on the combustion of pure methane and hydrogen-enriched methane (H2/CH4: 50/50 in vol%) fuels was investigated in a gas turbine model combustor under atmospheric conditions. The burner assembly was designed to mimic the geometry of an industrial burner, the Siemens DLE Burner, in which a concentric annular ring equipped with pilot flame burners is implemented in the dome of the combustor. Two pilot burner configurations have been investigated: a non-premixed and a partially premixed pilot arrangement. The performance of the pilot burners was evaluated for varying Reynolds number (Re) and H2 enrichment. High-speed OH∗ chemiluminescence imaging, as well as simultaneous planar laser-induced fluorescence measurements of the OH radicals and formaldehyde (CH2O) were used for evaluating the dynamics and structures of the flames for different conditions. Furthermore, emission measurements were carried out to determine the influence of hydrogen dilution on the NOx and CO emission levels. The main findings are (a) the effect of the pilot flame is sensitive to the Reynolds number of the main flame and the type of the pilot flame, (b) the stability range becomes narrower with increasing hydrogen ratio, due to the tendency to flashback, (c) non-premixed pilot flames lower the NOx and increase the CO emissions, albeit rather small differences in the emissions have been detected, and (d) the NOx and CO emissions become significantly lower with increasing hydrogen ratio.

Instantaneous flame front identification by Mie scattering vs. OH PLIF in low turbulence Bunsen flame

Simultaneous OH-PLIF and Mie scatter imaging were used to investigate turbulent premixed flame edge detection under a range of turbulence characteristics on a stabilised piloted Bunsen burner. A 527 nm wavelength laser beam is used to generate a Mie scattering sheet at 500 Hz, and a 283 nm wavelength laser sheet is created using 355 nm wavelength laser to pump an optical parametric oscillator to induce florescence from OH radicals at 5 Hz. A phase-locking technique is applied to synchronize and lock the two laser systems. The number density method has been used to detect flame edges in Mie scattering images, and three algorithms were applied to OH-PLIF images as a reference. A comparison of the methods and different parameter setting is made by using the metrics of location difference, flame surface density and curvature of flame edges. The processed data show that once a well-tuned window size is determined by applying the number density method, averaged spatial differences between Mie scattering images and OH-PLIF images are of the order of or smaller than the laminar flame thickness, demonstrating that under these conditions, high frequency Mie scatter measurements can be used as well as OH-PLIF images to define the flame edge at that spatial resolution. The positive result confirms that double-frame Mie scattering allows the measurement of high frequency conditional velocity distributions and flame properties simultaneously using solely Mie scattering, provided that the particle density is suitably designed to be around 16 px^2 per particle.Graphic

Structure and scalar correlation of ammonia/air turbulent premixed flames in the distributed reaction zone regime

Instantaneous structures of turbulent premixed ammonia/air flames on a piloted jet burner were investigated using simultaneous planar laser-induced fluorescence (PLIF) and Rayleigh thermometry measurements. Two-dimensional spatial distributions of temperature were simultaneously measured with those of the NH radical and the NO pollutant, respectively. Experiments were conducted for stoichiometric flames under five jet velocities. All flames are located in the distributed reaction zone regime of the Borghi-Peters diagram with the Karlovitz (Ka) number ranging from 274 to 4720. The NH PLIF images are used to characterize the fuel consumption layer of the reaction zones since the formation of NH is associated with the consumption of ammonia. The NH PLIF results show that under all flame conditions investigated, the NH layer remains thin in the proximity of the burner while it becomes progressively thickened and distorted by turbulence with increasing turbulent intensity and axial distance. For flames with Ka of 274, the NH layer essentially remains thin, while at Ka of 590 or higher, significant broadening of the NH layer is observed. Probability density functions (PDFs) of the NH layer thickness show that the NH layer can be broadened by 3 – 4 times as the flames are developed downstream. The broadening of the NH layer is considered to indicate that the flames are in the distributed reaction zone regime. The boundary between the thin-reaction zone regime and the distributed reaction zone regime occurs at a much larger Ka than that in methane/air flames. The broadening of the NH layer is due to the penetration of the turbulent eddies and the merging of flame branches. The latter occurs mainly near the flame tips. NO is shown to exist in a wide region in space, across the preheat zone, reaction zone, and postflame zone. NO formation occurs mainly in the reaction zone, however, it is transported by turbulence eddies to the preheat zone and by convection to the postflame zone. The temperature measurements indicate that the preheat zone is broadened in all flames investigated. The broadening of the preheat zone is moderately sensitive to the Ka number while it is more sensitive to the integral length scale of the flames.

Resolvent-based modelling of coherent structures in a turbulent jet flame using a passive flame approach

Motivated by the recent success in finding coherent structures in turbulent flows and describing their noise emission using the Resolvent Analysis (RA), the method is applied to a turbulent jet flame at Re=15,000 and a corresponding non-reacting flow to investigate their axisymmetric dynamics. The RA, which in this study assumes a passive flame and neglects compressibility effects, is based on the governing equations linearized around the temporal mean state. It is validated against Spectral Proper Orthogonal Decomposition (SPOD) obtained from time-resolved snapshots. Both the temporal mean state and the snapshots are obtained by Large Eddy Simulation (LES). The SPOD reveals that an axisymmetric, convective Kelvin–Helmholtz (KH) instability is the dominant hydrodynamic mechanism in the jet flame within a narrow frequency band and incorporates up to 40% of the turbulent kinetic energy. Results show that the RA is capable of reproducing the mode shapes seen in the SPOD. The RA furthermore allows to address the origin of these hydrodynamic structures: While the corresponding KH mode in a non-reacting turbulent jet flow is most sensitive to perturbations in the nozzle boundary layer, the same dominant mode in the turbulent Bunsen flame is most receptive to perturbations in the region between the nozzle edge and the annular pilot burner. The results suggest that the strong density gradients in this region initiate perturbations in the baroclinic torque, which are feeding the KH mode. Finally, a linear stability analysis proves that the high sensitivity of the KH structure is due to resonance with stable linear eigenmodes, which explains its high energy content. By applying the RA to a turbulent reacting flow, this study opens up a new pathway in analyzing the role of hydrodynamic structures in reacting flows.

Increasing the Efficiency and Increasing the Resource of the Plasma-Ignition System by Its Modernization at Gusinoozerskaya TPP

The article is devoted to a very urgent problem: reducing the cost of the fuel component in the production of electricity at power plants in Russia, namely, abandoning expensive fuel oil during the kindling of the boiler and the transitioning to the use of coal dust for this purpose. One of the ways to organize such kindling is the use of plasma technology to ignite coal dust. This technology is based on the thermochemical preparation of pulverized coal using an electric arc arising between the electrodes of the plasmatron. A stream of air passes through the arc, forming a plasma, which, meeting with the stream of air mixture, heats it, and promotes the release of volatile substances and the ignition of coal dust. Back in 1994, the first experiments on the implementation of such a system were carried out at the Gusinoozerskaya TPP. It turned out to be effective, but it had a number of significant drawbacks that limited its use. The main one was the low service life of the plasmatron cathode and muffle burner. In 2019, work was organized to modernize the plasma system aimed at increasing the resource of the main units of the plasma-ignition system. To solve a complex of problems, the specialists of OAO VTI proposed technical solutions for the design of a muffle burner, a cleaning system, and the automatic regulation of water and air supply to the plasma torch; a software package was developed to control the operation of the oil-free plasma-ignition system and control its parameters. Installation and testing of the modernized system for one of the pilot burners of the TPE-215 boiler was carried out. The specialists of the Institute of Physics and Mathematics (Siberian Branch, Russian Academy of Sciences) developed the design of the plasmatron and carried out its start-up testing. It is recommended to apply the results of the work to the rest of the boiler ignition burners. This article is devoted to the experience of upgrading the existing oil-free ignition system at the Gusinoozerskaya TPP.

Experimental Investigation on the Effects of the Geometry of the Pilot Burner on Main Flame

Various kinds of pilot burners were experimentally investigated to examine the effects of their geometry and their location relative to the main burner of a real size combustor. In addition, a wide range of fuel equivalence ratios were investigated to analyze the feasibility of the novel pilot burner for the conventional burner application. From the results, it is shown that the novel pilot burner with multi air holes had a thin, straight, long and stable pilot flame, while the conventional pilot burner had a thick, lifted, short and unstable flame. It is also shown that the novel pilot burner with an upper air flow hole had a straight pilot flame which led to less thermal damage to the burner combustor. This study suggests that not only pilot burner flame shape but also the vertical location of the pilot burner from the main burner combustor has a significant effect on combustor durability.

Smoke Emission Properties of Floor Covering Materials of Furnished Apartments in a Building.

The paper presents results of tests related to smoke optical density conducted on four various textile floor coverings for the needs of building interior design. Smoke emission is one of basic elements that characterize the fire environment. Consequently, the objective of the paper was to carry out a comparative analysis of smoke generation of chosen floor coverings for selected thermal exposures and in the presence or absence of a stimulus igniting the volatile gaseous phase (pilot flame). For the needs of our experimental research use was made of polypropylene, polyester, composite of wool, cotton, viscose and polyamide floor coverings. The highest value of the maximum specific optical density of smoke (494.7) was recorded for the floor covering consisting of 100% polypropylene (with higher fiber) under flameless combustion conditions (without the pilot flame). The polypropylene floor covering without underlay proved to be the best material from among all the tested ones with respect to smoke generating properties, and its samples offered the lowest value of optical density after 4 min for testing variants without the application of a pilot burner, with the flammable phase of decomposition products of this sample during the testing in which the burner was used to ignite at the latest. Experimental research has been carried out based on the standard ISO 5659–2:2017–08. The tests results were compared with international optical smoke density requirements for the interior design of ships and trains.

Combustion of Lean Methane–air Flames in Mesoscale Reactor with Opposite Gas Flows

ABSTRACT In this work, we study a countercurrent premixed rich-lean coaxial reactor to realize an overall lean combustion of hydrocarbon fuels. Flame topology and stability of the axially symmetric reaction fronts of methane-air mixtures are investigated both numerically and experimentally. These studies show that depending on the equivalence ratio of the mixture fed into the inner tube, playing the role of supporting a pilot burner, there can occur two or three-layered stable flame structures. It is demonstrated that flames can be stabilized over a wide range of mixture compositions and flow rates. In particular, it is possible to stabilize methane-air flames with the overall equivalence ratio below the lean flammability limit for this mixture due to the existence of the weak supporting flame and combined effect of the flame stretch and heat recirculation realized in the examined configuration. The diverse unsteady combustion modes, including flame oscillations and flame periodic extinction and ignition, are also found. The prospects of further investigations are discussed.

Factors Determining the Flame Configuration and Affecting Combustion Stability in Gas-Turbine Combustors

The possibilities of influencing combustion stability during changeover to low-emission combustion and ways of extending the stable combustion range are analyzed. The flow velocity, temperature, and pressure in the low-emission combustor (LEC) are considered as influencing factors. A premixed swirl-stabilized combustor is considered. The burner unit consists of main and pilot burners. The main burner has two fuel channels that allow controlling the quality of the air-fuel mixture. The LEC developed for an aeroderivative gas turbine was tested at an inlet air pressure of 2 MPa and an inlet air temperature of 475°C and an exhaust gas temperature of up to 1320°C.

Improved MMC-LES to compute the structure of a mixed-mode turbulent flame series

An improved version of the Lagrangian multiple mapping conditioning model coupled with large eddy simulation (MMC-LES) is applied to compute the structure of a range of turbulent mixed-mode flames stabilised on the Sydney piloted burner with compositionally inhomogeneous inlet. The calculations are compared with detailed measurements. While premixed MMC-LES models are yet to be developed, the most commonly deployed version and code for MMC-LES uses a mixture-fraction-based approach and a sparse-Lagrangian notional particle method that is most suitable for non-premixed combustion. The improvements reported here are due to (i) a more rigorous density coupling approach, (ii) a more refined mixing time scale, and (iii) selective particle intensification to improve localness in physical space as well as mixture fraction space. This intensification is selectively applied in upstream regions where mixed-mode combustion dominates and is relaxed further downstream as the jet flames transition to a non-premixed flame structure. The computed results show good agreement with experimental data hence confirming the feasibility of the improved MMC-LES approach in being able to account for mixed-mode combustion as well as for finite-rate chemistry effects. These promising results warrant future extension of the selective particle intensification method to become automatically adaptive.

100 kHz PIV in a liquid-fueled gas turbine swirl combustor at 1 MPa

Simultaneous 100 kHz particle image velocimetry (PIV) and 10 kHz OH* chemiluminescence (CL) were used to investigate flow and flame dynamics in a liquid-fueled, swirl-stabilized, piloted burner operated at 1.0 MPa. The PIV measurements were focused on the inner recirculation zone (IRZ), which forms downstream of an annular bluff-body feature that separates the pilot and main reactant jets and plays a critical role in flame stabilization. The OH* CL images captured the large-scale flame structure and dynamics. For the operating condition studied in this work, a self-excited combustion instability was present and caused axisymmetric variations in flame length and global heat release at a frequency of 810 Hz. Dynamic Mode Decomposition (DMD) was performed on the measured velocity fields to isolate fluctuations associated with the thermoacoustic mode from other dynamic flow processes. The DMD results showed that the 810 Hz instability causes strong fluctuations of both the axial and radial velocity components within the shear layer between the pilot jet and IRZ, along with concomitant changes in the size and shape of the IRZ. The DMD spatial modes also revealed periodic generation of vortices within the pilot-IRZ shear layer at frequencies ranging from 4–5.5 kHz. Wavelet analysis was used to study the interaction between these smaller-scale flow structures and the large-scale flow-flame dynamics associated with the combustion instability. The frequency magnitude related to vortex shedding was shown to fluctuate with the 810 Hz instability. The peak frequency magnitude followed the maximum radial velocity in the shear layer, which occurs when the IRZ is at its farthest radial extent and the velocity gradients in the pilot-IRZ shear layer are the strongest. The characterization of cross-scale, flow-flame coupling in this highly turbulent, high-pressure flame was enabled by the state-of-the-art 100 kHz PIV measurements.

Low-Emission Operation of Aeroderivative Gas-Turbine Combustor over a Wide Range of Ambient Conditions

The capabilities of controlling a low-emission combustor (LEC) over a wide range of ambient conditions are analyzed. The LES is intended for a GTU-16P gas turbine that is a derivative of the PS-90A aircraft engine by the UEC Aviadvigatel company. The LEC is of premix swirl stabilized type based on GTE-110 prototype. Its burner consists of pilot and main burners. The main burner has two fuel supply channels that allow controlling the quality of the air-fuel mixture. The low-emission operation range of the LEC can be extended to 70% load at negative ambient temperatures by bleeding air to the compressor inlet.

Effect of differential diffusion on turbulent lean premixed hydrogen enriched flames through structure analysis

This study presents the flame structure influenced by the differential diffusion effects and evaluates the structural modifications induced by the turbulence, thus to understand the coupling effects of the diffusively unstable flame fronts and the turbulence distortion. Lean premixed CH4/H2/air flames were conducted using a piloted Bunsen burner. Three hydrogen fractions of 0, 30% and 60% were adopted and the laminar flame speed was kept constant. The turbulence was generated with a single-layer perforated plate, which was combined with different bulk velocities to obtain varied turbulence intensities. Quasi-laminar flames without the plate were also performed. Explicit flame morphology was obtained using the OH-PLIF. The curvature, flame surface density and turbulent burning velocity were measured. Results show that the preferential transport of hydrogen produces negatively curved cusps flanked with positively curved bulges, which are featured by skewed curvature pdfs and consistent with the typical structure caused by the Darrieus-Landau instability. Prevalent bulge-cusp like wrinkles remain with relatively weak turbulence. However, stronger turbulence can break the bulges to be finer, and induce random positively curved cusps, therefore to destroy the bulge-cusp structures. Evident positive curvatures are generated in this process modifying the skewed curvature pdfs to be more symmetric, while the negative curvatures are not affected seriously. From low to high turbulence intensities, the hydrogen addition always strengthens the flame wrinkling. The augmentation of flame surface density and turbulent burning velocity with hydrogen is even more obvious at higher turbulence intensity. It is suggested that the differential diffusion can persist and even be strengthened with strong turbulence.

Estimación de las propiedades físico-químicas de residuos agroindustriales para el aprovechamiento como biocombustible


 In Ecuador maize (Zea mays L) it´s produced in the coastal, Andean and Amazon region, 45.521 hectares are harvested annually in Manabí. On the other hand, peanuts (Arachishypogaea) are another important crop in Manabí agriculture. Within the different agricultural or processing processes, heterogeneous waste, especially biomass, which represents an environmental problem due to the lack of techniques for its use, remaining in the field in the form of waste, which creates pollution problems. An assessment was made of the physicochemical properties that influence energy potential (humidity, ash, fixed carbon and volatile material) of these residues specifically of corn stalk (TM) and peanut shell (CM) for use in the development of a solid biofuel (péllet). CM's moisture content was 11.45% and TM 10.83%. The highest ash content in CM 18.93% and a lower content at TM=11.93%. The fixed carbon content in CM=15.78% and in TM=23.11%, similar values were obtained in the volatile material content between the two residues (CM=65.47% and TM=64.96%), these results indicate that the selected waste can be used for power generation as solid biofuels. In a pilot burner, pellets were burned for each selected agro-industrial waste reaching a maximum temperature of 751±39 °C for CM and 653±13 °C for TM in time of 9 and 4 minutes respectively.
 
 
 Index Terms— biomass, energy potential, solid biofuel.