scholarly journals Mitigating Thermal NOx by Changing the Secondary Air Injection Channel: A Case Study in the Cement Industry

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 220
Author(s):  
Domenico Lahaye ◽  
Mohamed el Abbassi ◽  
Kees Vuik ◽  
Marco Talice ◽  
Franjo Juretić
Keyword(s):  
Spatial Distribution ◽  
Heat Release ◽  
Cement Industry ◽  
Inlet Channel ◽  
Nox Formation ◽  
Premixed Turbulent Combustion ◽  
Air Inlet ◽  
Air Flows ◽  
Secondary Air ◽  
Thermal Nox

This work studies how non-premixed turbulent combustion in a rotary kiln depends on the geometry of the secondary air inlet channel. We target a kiln in which temperatures can reach values above 1800 degrees Kelvin. Monitoring and possible mitigation of the thermal nitric-oxide (NOx) formation is of utmost importance. The performed reactive flow simulations result in detailed maps of the spatial distribution of the flow, thermodynamics and chemical conditions of the kiln. These maps provide valuable information to the operator of the kiln. The simulations show the difference between the existing and the newly proposed geometry of the secondary air inlet. In the existing configuration, the secondary air inlet is rectangular and located above the base of the burner pipe. The secondary air flows into the furnace from the top of the flame. The heat release by combustion is unevenly distributed throughout the flame. In the new geometry, the secondary air inlet is an annular ring placed around the burner pipe. The secondary air flows circumferentially around the burner pipe. The new secondary air inlet geometry is shown to result in a more homogeneous spatial distribution of the heat release throughout the flame. The peak temperatures of the flame and the production of thermal NOx are significantly reduced. Further research is required to resolve limitations of various choices in our modeling approach.

Reaction of Fuel NOx Formation for Gas Turbine Conditions

1998 ◽  
Vol 120 (3) ◽  
pp. 474-480 ◽  
Author(s):  
T. Nakata ◽  
M. Sato ◽  
T. Hasegawa
Keyword(s):  
Gas Turbine ◽  
Coal Gasification ◽  
Combustion Process ◽  
Combined Cycle ◽  
Inlet Section ◽  
Mixing Condition ◽  
Nox Formation ◽  
Air Inlet ◽  
Secondary Air ◽  
Fuel Nox

Ammonia contained in coal-gasified fuel is converted to nitrogen oxides (NOx) in the combustion process of a gas turbine in integrated coal gasification combined cycle (IGCC) system. Research data on fuel-NOx formation are insufficient, and there still remains a wide explored domain. The present research aims at obtaining fundamental knowledge of fuel-NOx formation characteristics by applying reaction kinetics to gas turbine conditions. An instantaneous mixing condition was assumed in the cross section of a gas turbine combustor and both gradual mixing condition and instantaneous mixing condition were assumed at secondary air inlet section. The results may be summarized as follows: (1) in the primary combustion zone under fuel rich condition, HCN and other intermediate products are formed as ammonia contained in the fuel decomposes; (2) formation characteristics of fuel-NOx are affected by the condition of secondary air mixing; and (3) the conversion ratio from ammonia to NOx declines as the pressure inside the combustor rises under the condition of gradual mixing at the secondary air inlet. These results obtained agreed approximately with the experimentation.

scholarly journals Experimental Investigation of an Atmospheric Rectangular Rich Quench Lean Combustor Sector for Aeroengines

1997 ◽  
Author(s):  
Peter Griebel ◽  
Michael Fischer ◽  
Christoph Hassa ◽  
Eggert Magens ◽  
Henning Nannen ◽  
...  
Keyword(s):  
Research Work ◽  
Nox Formation ◽  
Lean Combustion ◽  
Air Jets ◽  
Primary Zone ◽  
Low Emission ◽  
Measuring Techniques ◽  
Annular Combustor ◽  
High Turbulence ◽  
Secondary Air

In this research work the potential of rich quench lean combustion for low emission aeroengines is investigated in a rectangular atmospheric sector, representing a segment of an annular combustor. For a constant design point (cruise) the mixing process and the NOx formation are studied in detail by concentration, temperature and velocity measurements using intrusive and non-intrusive measuring techniques. Measurements at the exit of the homogeneous primary zone show relatively high levels of non-thermal NO. The NOx formation in the quench zone is very low due to the quick mixing of the secondary air achieved by an adequate penetration of the secondary air jets and a high turbulence level. The NOx and CO emissions at the combustor exit are low and the pattern factor of the temperature distribution is sufficient.

CFD Based Analysis of Burner Fuel Air Mixing Over a Range of Air Inlet and Fuel Pre-Heat Temperatures for a Siemens V94.3A Gas Turbine Burner

2006 ◽  
Author(s):  
O. R. Darbyshire ◽  
C. W. Wilson ◽  
A. Evans ◽  
S. B. M. Beck
Keyword(s):  
Gas Turbine ◽  
Computational Effort ◽  
Ambient Conditions ◽  
Fuel Gas ◽  
3 Dimensional ◽  
Continuity Equations ◽  
Air Inlet ◽  
Air Mixing ◽  
Inlet Conditions ◽  
Thermal Nox

The homogeneity of the fuel/air mix entering the combustion chamber of a gas turbine is known to be a factor in both the emissions performance (with poor mixing resulting in local hotspots and the formation of thermal NOx) and the generation of acoustic vibrations (humming). Obviously it is desirable to reduce both pollutants and unwanted acoustics as far as possible. The aim of this paper is to study the relationship between the local inlet conditions and the mixing of the fuel and air, specifically looking at the effects of fuel gas preheating and inlet air temperature on mixedness at the combustor inlet. A CFD model of the lean pre-mixed combustor for a Siemens v94.3A gas turbine was used to analyse the problem. The 3-dimensional model employs a structured mesh scheme and uses the symmetry of the burner to reduce computational effort. The model was solved using a 2nd order discretisation of the momentum and continuity equations along with the RNG k-ε turbulence model to provide closure. The boundary conditions for the model were taken from data obtained from in service measurements. Several runs were made using air inlet temperatures varying from −10°C to 30°C and gas inlet temperatures from 10°C to 450°C. The data obtained from the CFD simulations was processed to give an indication of the quality of the fuel/air mixing for each set of inlet conditions. This was then used to create a tool which can be used to determine the amount of gas pre-heat required to achieve the best possible mixing for a given set of ambient conditions. An estimation of the NOx produced at different conditions was derived from the mixing data. Analysis of the results showed that increasing the gas preheat produces an improvement in the mixing of the fuel and air in the burner. This improvement in mixing also resulted in a reduction in the estimated amount of NOx produced.

The Effects of Air Flow Rates, Secondary Air Inlet Geometry, Fuel Type, and Operating Mode on the Performance of Gasifier Cookstoves

2016 ◽  
Vol 50 (17) ◽  
pp. 9754-9763 ◽  
Author(s):  
Jessica Tryner ◽  
James W. Tillotson ◽  
Marc E. Baumgardner ◽  
Jeffrey T. Mohr ◽  
Morgan W. DeFoort ◽  
...  
Keyword(s):  
Air Flow ◽  
Operating Mode ◽  
Fuel Type ◽  
Flow Rates ◽  
Air Inlet ◽  
Inlet Geometry ◽  
Secondary Air

Dynamic Characteristics of a Small Fixed-Bed Gasifier Stove

1996 ◽  
Vol 210 (1) ◽  
pp. 35-45
Author(s):  
D Beedie ◽  
N Syred ◽  
T O'Doherty
Keyword(s):  
Fixed Bed ◽  
Calorific Value ◽  
Fuel Gas ◽  
Mixture Ratio ◽  
Biomass Stove ◽  
Air Inlet ◽  
Multi Stage ◽  
Air Supply ◽  
Simple Measurement ◽  
Secondary Air

This paper describes work directed at characterizing the dynamic behaviour of a small gasifying fixed-bed biomass stove. The system comprises a primary gasification chamber, followed by a multi-stage secondary combustor which can allow for the considerable variation in quantity and calorific value of fuel gas produced by forming a series of flamelets which move along the length of the secondary combustor as a function of the local mixture ratio. The typical cycle time is about 60 minutes and once warmed up the unit is capable of operating with low emissions, providing appropriate guidelines are followed. Correlation of temperature and gas concentration measurements on the unit with velocity and flow visualization measurements on a perspex model of the secondary combustor show that improvements can be made to the flow patterns in the bottom of the secondary combustion chamber by reducing the size and shape of the recirculation zones formed and revising the location of the mid-section secondary air inlet. Control of the system is indicated using a simple measurement of temperature in the secondary combustor to determine appropriate air supply rates.

scholarly journals Effects of Secondary Air Flows on Thermal Characteristics and Particle Behavior in Flame Spray Process

2014 ◽  
Vol 55 (5) ◽  
pp. 850-856 ◽  
Author(s):  
Jae Bin Lee ◽  
Dong Hwan Shin ◽  
Yeo Hae Lee ◽  
Dae Yun Kim ◽  
Seong Hyuk Lee
Keyword(s):  
Thermal Characteristics ◽  
Flame Spray ◽  
Particle Behavior ◽  
Spray Process ◽  
Air Flows ◽  
Secondary Air
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