High temperature air combustion: sustainable technology to low NOx formation

In recent decade, more stringent laws have been ordained to cope with environmental issues and global warming. Industrial sectors have been urged to substitute new combustion methods to decline their emissions, but the cost of pollutant reduction in traditional combustion is efficiency abatement. In the other word, emission and fuel consumption cannot be declined simultaneously by conventional combustion. High temperature air combustion (Hitac) is an innovative substitution for conventional combustion which has been developed to increase combustion efficiency and to decline pollutant formation contemporaneously. Recently, some valuable experimental and numerical analysis have been done to study the variety aspects of Hitac and to study the reasons of the compatibility of high efficiency and low NOx production in Hitac area. The outstanding characteristic of Hitac is its sustainability under low oxygen concentration when the combustion air is preheated more than the fuel auto-ignition temperature. Therefore, it can be observed that thermal NOx is suppressed due to lack of oxygen concentration. This paper is concerned with NOx formation reduction in Hitac systems via physical and chemical analysis. Chemical kinetic, heat transfer concepts, simulation studies and experimental investigations have been employed to analyze NOx formation mitigation in Hitac method

Pollutant reduction and energy saving in industrial sectors by applying high temperature air combustion method

In recent decade energy demand and oil resources limitation have been appeared as one of the main concerns of humankind and this fact has led scientists to find efficient ways for fuel combustion. In conventional combustion, the pollutants reduction is associated with losses efficiency. In other word, low pollutant and high efficiency are not fulfilled simultaneously by applying traditional combustion. High temperature air combustion (Hitac) is a new technology in combustion which has received more attention during this decade because of low emissions and more energy saving. Experiments illustrate that the flame is disappeared when preheated and diluted oxidizer is applied in Hitac. Although, low concentration of oxygen is charged in Hitac furnace, sustainability of combustion is fulfilled when oxidizer is preheated higher than fuel auto-ignition temperature. This review paper tries to show the importance of Hitac systems in energy saving and abatement of pollutant formation, and discuses about necessity of transient from conventional combustion to Hitac in industrial sectors. © 2012 Praise Worthy Prize S.r.l. - All rights reserved

High temperature air combustion: Sustainable technology to low NO\u3csub\u3eX\u3c/sub\u3e formation

In recent decade, more stringent laws have been ordained to cope with environmental issues and global warming. Industrial sectors have been urged to substitute new combustion methods to decline their emissions, but the cost of pollutant reduction in traditional combustion is efficiency abatement. In the other word, emission and fuel consumption cannot be declined simultaneously by conventional combustion. High temperature air combustion (Hitac) is an innovative substitution for conventional combustion which has been developed to increase combustion efficiency and to decline pollutant formation contemporaneously. Recently, some valuable experimental and numerical analysis have been done to study the variety aspects of Hitac and to study the reasons of the compatibility of high efficiency and low NOx production in Hitac area. The outstanding characteristic of Hitac is its sustainability under low oxygen concentration when the combustion air is preheated more than the fuel auto-ignition temperature. Therefore, it can be observed that thermal NOx is suppressed due to lack of oxygen concentration. This paper is concerned with NOx formation reduction in Hitac systems via physical and chemical analysis. Chemical kinetic, heat transfer concepts, simulation studies and experimental investigations have been employed to analyze NOx formation mitigation in Hitac method. © 2012 Praise Worthy Prize S.r.l. - All right reserved

Pollutant reduction and energy saving in industrial sectors by applying high temperature air combustion method

In recent decade energy demand and oil resources limitation have been appeared as one of the main concerns of humankind and this fact has led scientists to find efficient ways for fuel combustion. In conventional combustion, the pollutants reduction is associated with losses efficiency. In other word, low pollutant and high efficiency are not fulfilled simultaneously by applying traditional combustion. High temperature air combustion (Hitac) is a new technology in combustion which has received more attention during this decade because of low emissions and more energy saving. Experiments illustrate that the flame is disappeared when preheated and diluted oxidizer is applied in Hitac. Although, low concentration of oxygen is charged in Hitac furnace, sustainability of combustion is fulfilled when oxidizer is preheated higher than fuel auto-ignition temperature. This review paper tries to show the importance of Hitac systems in energy saving and abatement of pollutant formation, and discuses about necessity of transient from conventional combustion to Hitac in industrial sectors

Low-NOX combustion of biogas from palm oil mill effluent using flameless combustion

An experimental study of flamelesscombustion in a laboratory-scale furnace using naturalgas, simulated biogas and palm-oil-mill-effluent(POME) derived biogas. Flameless combustion regimeis achieved fornatural gas, simulated biogas and POMEbiogas. POME biogas flameless combustion has slightlylower average furnace temperature (2.69% reduction)due to increased inert gas in the furnace chamber.Flameless combustion produce larger and more uniformcombustion area (Rtu= 0.097) compared to conventionalflame combustion(Rtu=0.21). NOXemissionmeasurement has shown reduced NOXemission inflameless combustionof natural gas, POME biogas andsimulated biogas with average of 6 ppm

Characterization of a low NOx flameless combustion burner using natural gas

Flameless combustion is a method that has a great potential in reducing pollutant emission from combustion process. In this work, the operation and emission of a laboratory scale furnace under the flameless combustion regime using natural gas as a fuel was examined. In the experimental setup, the combustor was equipped with parallel jet burner systems with controlled gas fuel and oxidizer. Several ports have been integrated in the combustor to allow for temperature and combustion emission measurement. In the study, a comparison between flameless combustion with and without preheated combustion air has been made. The atmospheric air was heated to near the auto ignition temperature by a coil placed within the furnace assembly. The results show that flameless combustion mode could be obtained with and without preheated combustion air. The results also revealed that the laboratory scale furnace could successfully operate in flameless combustion regime using natural gas as fuel. In terms of emission, it was found that flameless combustion was more effective than the conventional combustion in reducing the rate of NOX emissio

Effects of equivalence ratio on asymmetric vortex combustion in a Low NOx Burner

This study presents a combustor with high combustion efficiency and low emissions. The flow field in a combustion chamber is significant in achieving good fuel–air mixing. The experimental and computational results of the temperature and emission of a vortex combustor are presented. Air enters into the combustor in a tangential direction relative to the combustor axis to produce vortex flow, which facilitates the recirculation of hot gas near the fuel nozzle for enhanced mixing. Propane is injected in the direction of the combustor axis at variable mass flow rates to produce variations in the equivalence ratio. The temperature measured along the center line of the combustor. The lowest temperature is measured under rich conditions first and then under lean and stoichiometric conditions. The trend of the combustor temperature at varying equivalence ratios is reproduced well in the simulation despite the increasing temperature near the inlet. An expected trend of NOx is measured at the outlet where the lowest NOx is produced by the rich combustion first, followed by the lean and stoichiometric combustion. The relative NOx emission at different equivalence ratios is reproduced well in the simulation, although the magnitude of the NOx emission is reduced. As indicated by the calculated number of swirls, the combustion under rich conditions produces about 15% more swirls near the nozzle compared with that under stoichiometric conditions as a result of the low combustor temperature. Moreover, such rich conditions produce a more uniform temperature inside the combustor than lean and stoichiometric conditions

Effects of firing mode on the performance of flameless combustion: A review

Flameless combustion is of a great interest since it simultaneously provides higher thermal efficiency together with controlling the pollutant emission such as NOX. This technology has been used to provide large energy savings in power system and industrial heating applications. In this technology, the preheat temperature of the combustion air must be higher than the autoignition temperature of the reactant mixture. In this review, papers concerning the effect of firing mode to reduce pollutant emissions such as NOX emission and combustion efficiency for flameless combustion were reviewed. Summaries on the influences of the firing mode in the flameless combustion were presented, discussed and analyzed. The review concludes that all the previous studies have asserted that a parallel firing mode gives much lower pollutant emissions and high efficiency compared with staggered and counter modes. © (2013) Trans Tech Publications, Switzerland

Review of numerical studies on nox emission in the flameless combustion

The incomplete process of combustion produces unwanted emission and one of the major pollutant in the combustion of fossil fuels is the formation of nitrogen oxides. To mitigate the problem various combustion technologies have been explored and flameless combustion is one of the potential candidate. Flameless combustion is of a great interest since it simultaneously provides higher thermal efficiency together with controlling the pollutant emission such as NOX. In this technology, the preheat temperature of the combustion air must be higher than the auto-ignition temperature of the reactant mixture. This paper explores various numerical studies performed on the flameless combustion and the role of flameless combustion on the reduction of NOX emission are presented