The Effect of Distance Between Fuel and Oxidizer Nozzles on NOx Emission From High Temperature Air Combustion

2011 ◽  
Author(s):  
Yuzuru Nada ◽  
Yasutomo Zenman ◽  
Takahiro Ito ◽  
Susumu Noda
Keyword(s):  
High Temperature ◽  
Flame Temperature ◽  
Dilution Effect ◽  
Nox Emission ◽  
Emission Characteristics ◽  
High Temperature Air Combustion ◽  
Flamelet Model ◽  
Scaling Parameters ◽  
Fuel Nozzle ◽  
Emission Index

This study describes NOx emission characteristics of a high temperature air combustion furnace operating with parallel jet burner system. In the parallel jet burner system, fuel nozzles are separated with a distance from an oxidizer nozzle. Objectives of this study are to clarify the effect of the distance between the fuel nozzle and the oxidizer nozzle on NOx emission. The emission index of NOx (EINOx) decreases with the increase in the distance. This is due to the dilution through entrainment of burned gas. A scaling concept is proposed to assess the dilution effect on the NOx emission. Scaling parameters employed here are the global residence time of fuel and the flame temperature evaluated on a modified flamelet model in which the dilution effect is included. The overall EINOx production rate is scaled with the flame temperature. This scaling indicates the importance of the distance between the nozzles for NOx emission.

COMPUTATIONAL STUDY ON COMBUSTION AND EMISSION CHARACTERISTIC OF PILOTED FLAMES BY VARYING COMPOSITION CO2 OF SIMULATED BIOGAS

2017 ◽  
Vol 79 (7-3) ◽  
Author(s):  
Khor Chin Keat ◽  
M. F. Mohd Yasin ◽  
M. A. Wahid ◽  
A. Saat ◽  
A. S. Md Yudin
Keyword(s):  
Computational Study ◽  
Flame Temperature ◽  
Dilution Effect ◽  
Co2 Concentration ◽  
Nox Emission ◽  
Combustion Model ◽  
Emission Characteristic ◽  
Measured Temperature ◽  
Flamelet Model ◽  
Detailed Chemistry

This study investigates the performance of flamelet model technique in predicting the behavior of piloted flame.A non-premixed methane flame of a piloted burner is simulated in OpenFOAM. A detailed chemistry of methane oxidation is integrated with the flamelet combustion model using probability density function (pdf) approach. The turbulence modelling adopts Reynolds Average Navier Stokes (RANS) framework with standard k-ε model. A comparison with experimental data demonstrates good agreement between the predicted and the measured temperature profiles in axial and radial directions. Recently, one of major concern with combustion system is the emission of pollution specially NOx emission. Reduction of the pollutions can be achieved by varying the composition of CO2 in biogas. In addition, the effect of the composition of biogas on NOx emission of piloted burner is still not understood. Therefore, understanding the behavior composition of CO2 in biogas is important that could affect the emission of pollution. In the present study, the use of biogas with composition of 10 to 30 percent of CO2 is simulated to study the effects of biogas composition on NOx emission. The comparison between biogas and pure methane are done based on the distribution of NOx, CO2, CH4, and temperature at different height above the burner. At varying composition of CO2 in biogas, the NOx emission for biogas with 30 percent CO2 is greatly reduced compared to that of 10 percent CO2. This is due to the reduction of the post flame temperature that is produced by the dilution effect at high CO2 concentration.  

scholarly journals NOx Emission Characteristics of a Catalytic Combustor Under High-Temperature Conditions

1995 ◽  
Author(s):  
Martin Valk ◽  
Nicolas Vortmeyer ◽  
Günter Kappler
Keyword(s):  
High Temperature ◽  
Flame Temperature ◽  
Plug Flow ◽  
Nox Emission ◽  
Thermal Reactor ◽  
Emission Characteristics ◽  
Nox Emissions ◽  
Temperature Conditions ◽  
Conversion Rates ◽  
Catalytic Combustor

A catalytic combustor concept with short catalyst segments and a thermal reactor is investigated with regard to NOx production of this concept under high-temperature conditions. The maximum combustor exit temperature was more than 1800 K with catalyst temperatures below 1300 K. For combustion of iso-octane, NOx emissions of 4 ppm (dry, 15% O2) at a flame temperature of 1800 K were measured. No significant influence of catalyst length, reference velocity and overall residence time on NOx emissions was observed. Additionally, the test combustor was fuelled with commercial diesel and kerosene (Jet-A). In this case, NOx emissions were noticeable higher due to fuel-bound nitrogen. The emissions measured were for diesel, 12 ppm, and for kerosene, 7 ppm, (each dry, 15% O2), again at a flame temperature of 1800 K. To evaluate the conversion ratio of fuel-bound nitrogen to NOx iso-octane was doped with various amounts of ammonia and metyhlamine. The conversion rates were 70 to 90%, with a slight tendency to lower values (50%) for nitrogen mass fractions above 0.1%. Considering the NOx emission level of actual premix burners, the lower emission value of the presented catalytic combustor results from a perfect premixed plug-flow combustion system incorporating a catalyst herein and not from a specific advantage of the principle of catalytic combustion itself. Again similar to a premix-combustor are the NOx emission characteristics in the case of lean combustion of nitrogen bound fuels, which yield very high conversion rates.

Full Scale Testing of a Cluster Nozzle Burner for the Advanced Humid Air Turbine

2007 ◽  
Author(s):  
Tomomi Koganezawa ◽  
Keisuke Miura ◽  
Takeo Saito ◽  
Kazuki Abe ◽  
Hiroshi Inoue
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Pilot Plant ◽  
Flame Temperature ◽  
Nox Emission ◽  
Flame Stability ◽  
High Humidity ◽  
Humidity Condition ◽  
Air Turbine ◽  
High Humidity Condition

The advanced humid air turbine (AHAT) system, which has a humidifier and a heat recovery system has the advantage of improving the thermal efficiency of gas turbine power generation without needing an extremely high firing temperature and pressure ratio. A pilot plant and a prototype gas turbine adapted to the AHAT system have been developed. Before the pilot plant test, an experimental study using a combustion test rig was carried out to obtain the characteristics of a prototype combustor and it is described in this presentation. The combustion conditions in the AHAT system are characterized by both high humidity and high temperature air (17.6wt%, 629C). It is expected that a low flame temperature caused by the high humidity condition will decrease NOx emission while the high temperature air condition will sustain flame stability. However, the latter condition has the disadvantage of causing NOx emission and autoignition of fuel. A cluster nozzle burner configuration, which has many fuel and air coaxial jet streams, was previously proposed. The cluster nozzle burner can mix fuel and air effectively within a short time which makes it suited to the AHAT system and able to cope with both flame stability and NOx reduction problems. The combustion rig test results showed good combustion performance for the developed cluster nozzle burner. Both the high temperature condition of the AHAT system and the recirculation zone generated by swirling of center burner air sustained flame stability at a level sufficient for the nozzle burner in AHAT operation. The low flame temperature due to the high humidity condition was effective in decreasing NOx emission, which was less than 10ppm at 50-100% load.

scholarly journals Numerical Study of NOx Emission in High Temperature Air Combustion.

1998 ◽  
Vol 41 (2) ◽  
pp. 331-337 ◽  
Author(s):  
Hongsheng GUO ◽  
Yiguang JU ◽  
Kaoru MARUTA ◽  
Takashi NIIOKA ◽  
Jun'ichi SATO
Keyword(s):  
High Temperature ◽  
Numerical Study ◽  
Nox Emission ◽  
High Temperature Air Combustion

scholarly journals Effects of Turbulence on Flame Structure and NOx Emission of Turbulent Jet Non-Premixed Flames in High-Temperature Air Combustion

2005 ◽  
Vol 48 (2) ◽  
pp. 286-292 ◽  
Author(s):  
Hideaki KOBAYASHI ◽  
Ken OONO ◽  
Eun-Seong CHO ◽  
Hirokazu HAGIWARA ◽  
Yasuhiro OGAMI ◽  
...  
Keyword(s):  
High Temperature ◽  
Flame Structure ◽  
Premixed Flames ◽  
Turbulent Jet ◽  
Nox Emission ◽  
High Temperature Air Combustion

Study and Design on High Temperature Air Combustion of Hot Blast Stove

2014 ◽  
Vol 496-500 ◽  
pp. 1058-1062
Author(s):  
Fu Ming Zhang ◽  
Zu Rui Hu ◽  
Shu Sen Cheng
Keyword(s):  
High Temperature ◽  
Concentration Distribution ◽  
Cfd Simulation ◽  
Formation Rate ◽  
Flame Temperature ◽  
Combustion Process ◽  
High Temperature Air Combustion ◽  
Blast Stove ◽  
New Type ◽  
Hot Blast

During Hot Blast Stove (HBS) combustion, NOxforms rapidly when the flame temperature above 1420°C. In order to restrain the amount of NOxformation during combustion of HBS, the formation mechanism of NOxis investigated, and the NOxformation rate and amount in HBS are calculated by means of thermodynamic model. A new type of dome combustion HBS is developed based on high temperature air combustion (HTAC) technology. A comparison on the combustion process and characteristic of conventional HBS and HTAC HBS is performed by application of Computational Fluid Dynamics (CFD) simulation model. Temperature and concentration distribution, flame shape and NOxconcentration distribution of two kinds of stove are calculated. The result shows quite symmetrical HTAC stove temperature distribution. Under the same dome temperature, NOxamount is 80ppm only, reduced by approximate 76% in comparison with conventional stove.

Effects of Equivalence Ratio on the Emission and Temperature Characteristics of Spray Flames of Jet A/Butanol Blends Under Lean Conditions

2012 ◽  
Author(s):  
Tanjir H. Ratul ◽  
Ramkumar N. Parthasarathy ◽  
Subramanyam R. Gollahalli
Keyword(s):  
Equivalence Ratio ◽  
Flame Temperature ◽  
Nox Emission ◽  
Flame Height ◽  
Temperature Characteristics ◽  
Global Emission ◽  
Spray Flames ◽  
Index Level ◽  
Petroleum Fuels ◽  
Emission Index

Butanol is an attractive alternate fuel because it can be produced from renewable sources and has properties similar to those of petroleum fuels. Thus, blending butanol with petroleum fuels is a promising solution to reduce the dependence on petroleum fuels. In a previous study, we investigated the differences in the structure and emissions of Jet A and Butanol flames. The objective of this investigation was to study the emission and in-flame temperature characteristics of spray flames of Jet A/butanol blends at two equivalence ratios: 0.75 and 0.95. In addition to pure Jet A and pure butanol, blends of Jet A with 25%, 50% and 75% volumetric concentrations of butanol were used as fuel. The liquid fuel was atomized and combusted with air in a heated environment (479 K). The equivalence ratio was changed by altering the fuel flow rate, while maintaining the atomizing and coflow air flow rates constant, thus maintaining gas velocity field invariant. The global emission index of CO varied non-monotonically with the volume concentration of butanol in the blend at the lower equivalence ratio whereas the variation was gradual at the higher equivalence ratio. The global NOx emission index decreased monotonically as the butnaol content was increased at both equivalence ratios. The global NOx emission index level in the flames at equivalence ratio of 0.95 was higher than that at equivalence ratio of 0.75. At 25% flame height, the peak reaction zone was located off-axis; this radial location moved further away from the centerline as the equivalence ratio was increased. The peak temperatures were comparable in all the flames. The flames with butanol highlighted the effects of preferential vaporization of butanol.

Sign in / Sign up

Export Citation Format

Share Document