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.

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.

Influence of the characteristics of biogas generated in the leather industry on combustion quality

The treatment of protein waste in the leather industry also includes transformation into biogas through anaerobic digestion. A pilot plant producing biogas with a 45-60% CH4 concentration was designed for this purpose. Starting from primary experimental tests in a Bunsen burner, the paper presents the theoretical aspects of choosing the best combustion technique for this peculiar gaseous fuel in order to calculate the combustion velocity and checking the conditions for the flame stability. The applicability of the kinetic combustion (with pre-mix) will be attempted, because low combustion rates for this fuel also involve low air velocities. Diffusive combustion seems to not be affected by this impediment, as there is always an equality condition of flame velocity with burning speed, so a theoretical spot of a stable flame. After selecting the best combustion technique, a pilot burner will be designed and tested.

High Momentum Jet Flames at Elevated Pressure: Detailed Investigation of Flame Stabilization With Simultaneous Particle Image Velocimetry and OH-LIF

A model FLOX® combustor, featuring a single high momentum premixed jet flame, has been investigated using laser diagnostics in an optically accessible combustion chamber at a pressure of 8 bar. The model combustor was designed as a large single eccentric nozzle main burner (Ø 40 mm) together with an adjoining pilot burner and was operated with natural gas. To gain insight into the flame stabilization mechanisms with and without piloting, simultaneous particle image velocimetry (PIV) and OH laser-induced fluorescence (LIF) measurements have been performed at numerous two-dimensional (2D) sections of the flame. Additional OH-LIF measurements without PIV particles were analyzed quantitatively resulting in absolute OH concentrations and temperature fields. The flow field looks rather similar for both the unpiloted and the piloted cases, featuring a large recirculation zone next to the high momentum jet. However, flame shape and position change drastically. For the unpiloted case, the flame is lifted and widely distributed. Isolated flame kernels are found at the flame root in the vicinity of small-scale vortices. For the piloted flame, on the other hand, both pilot and main flame are attached to the burner base plate, and flame stabilization seems to take place on much smaller spatial scales with a connected flame front and no isolated flame kernels. The single-shot analysis gives rise to the assumption that for the unpiloted case, small-scale vortices act like the pilot burner flow in the opposed case and constantly impinge and ignite the high momentum jet at its root.

High Momentum Jet Flames at Elevated Pressure: B — Detailed Investigation of Flame Stabilization With Simultaneous PIV and OH-LIF

A model FLOX® combustor, featuring a single high momentum premixed jet flame, has been investigated using laser diagnostics in an optically accessible combustion chamber at a pressure of 8 bar. The model combustor was designed as a large single eccentric nozzle main burner (Ø 40 mm) together with an adjoining pilot burner and was operated with natural gas. To gain insight into the flame stabilization mechanisms with and without piloting, simultaneous Particle Image Velocimetry (PIV) and OH Laser Induced Fluorescence (LIF) measurements have been performed at numerous two-dimensional sections of the flame. Additional OH-LIF measurements without PIV-particles were analyzed quantitatively resulting in absolute OH concentrations and temperature fields. The flow field looks rather similar for both the unpiloted and the piloted case, featuring a large recirculation zone next to the high momentum jet. However, flame shape and position change drastically. For the unpiloted case, the flame is lifted, widely distributed and isolated flame kernels are found at the flame root in the vicinity of small scale vortices. For the piloted flame, on the other hand, both pilot and main flame are attached to the burner base plate, and flame stabilization seems to take place on much smaller spatial scales with a connected flame front and no isolated flame kernels. The single shot analysis gives rise to the assumption that for the unpiloted case small scale vortices act like the pilot burner flow in the opposed case and constantly impinge and ignite the high momentum jet at its root.

Extension of the Combustion Stability Range in Dry Low NOx Lean Premixed Gas Turbine Combustor Using a Fuel Rich Annular Pilot Burner

The present work is concerned with improving combustion stability in lean premixed (LP) gas turbine combustors by injecting free radicals into the combustion zone. The work is a joint experimental and numerical effort aimed at investigating the feasibility of incorporating a circumferential pilot combustor, which operates under rich conditions and directs its radicals enriched exhaust gases into the main combustion zone as the means for stabilization. The investigation includes the development of a chemical reactors network (CRN) model that is based on perfectly stirred reactors modules and on preliminary CFD analysis as well as on testing the method on an experimental model under laboratory conditions. The study is based on the hypothesis that under lean combustion conditions, combustion instability is linked to local extinctions of the flame and consequently, there is a direct correlation between the limiting conditions affecting combustion instability and the lean blowout (LBO) limit of the flame. The experimental results demonstrated the potential reduction of the combustion chamber's LBO limit while maintaining overall NOx emission concentration values within the typical range of low NOx burners and its delicate dependence on the equivalence ratio of the ring pilot flame. A similar result was revealed through the developed CHEMKIN-PRO CRN model that was applied to find the LBO limits of the combined pilot burner and main combustor system, while monitoring the associated emissions. Hence, both the CRN model, and the experimental results, indicate that the radicals enriched ring jet is effective at stabilizing the LP flame, while keeping the NOx emission level within the characteristic range of low NOx combustors.