Prediction of Combustion Efficiency and NOx Levels for Diffusion Flame Combustors in HAT Cycles

2002 ◽  
Author(s):  
Alexandr A. Belokon ◽  
Konstantin M. Khritov ◽  
Lev A. Klyachko ◽  
Sergey A. Tschepin ◽  
Vladimir M. Zakharov ◽  
...  
Keyword(s):  
Diffusion Flame ◽  
Atmospheric Pressure ◽  
Flame Temperature ◽  
Combustion Efficiency ◽  
Inlet Temperature ◽  
Preliminary Design ◽  
Test Results ◽  
Loading Parameter ◽  
Design Analyses ◽  
The Impact

Diffusion flame combustor test results are presented for methane firing in steam/air mixtures containing up to 20% steam. The tests were conducted at atmospheric pressure with combustor inlet temperatures up to 700K. Steam and air were fully premixed before combustion. Combustion efficiency and NOX levels were measured. The well-known Θ loading parameter was modified by replacing the combustor inlet temperature with the flame temperature. The flame temperature was defined as the stoichiometric temperature of the steam/air mixture. The combustion efficiency obtained with and without steam correlated nicely with this modified loading parameter. Calculated NOX levels agreed well with the measurements, where NOX was predicted using the flamelet technique. This approach makes it possible to predict combustor efficiencies with steam by using combustor performance data taken without steam. Preliminary design analyses of gas turbine cycles with significant steam addition can now easily include the impact of the steam on combustor performance.

Assessment of the Operational Performance of Fischer-Tropsch Synthetic-Paraffinic Kerosene in a T63 Gas Turbine Compared to Conventional Jet A-1 Fuel

2009 ◽  
Author(s):  
Nigel Bester ◽  
Andy Yates
Keyword(s):  
Gas Turbine ◽  
Thermal Loading ◽  
Flame Temperature ◽  
Combustion Products ◽  
Combustion Efficiency ◽  
Efficiency Gain ◽  
Engine Efficiency ◽  
Exit Temperature ◽  
The Impact ◽  
Combustor Liner

The performance implications of operating on Synthetic-Paraffinic Kerosene (SPK) were investigated using a RR-Allison T63-A-700 Model 250-C18 B gas turbine and compared to conventional Jet A-1. The SPK was aromatic–free and possessed a greater hydrogen/carbon ratio than petroleum derived Jet A-1. The variation in aromatic content had several implications with respect to soot and NOx emissions. Reduced aromatics also implied a reduction in the radiative heat transfer to the combustor liner. A simple model was used to explore the effect of H/C ratio on the adiabatic flame temperature, the combustor exit temperature and the engine efficiency via the impact on the gas properties and these were compared to the experimental data. It was found that operation with SPK changed directionally toward improving energy extraction via a turbine and an overall efficiency gain of about 1.2% was attained with operation on SPK through increased combustion efficiency, a reduction in liner pressure loss and an improvement in the combustion products properties. A modified combustion liner was fitted to enable the thermal loading on the combustor liner to be investigated and the expected trend with the SPK fuel was confirmed and quantified.

Impact of Secondary Air Flow on Combustor Emissions

2020 ◽  
Author(s):  
Bassam S. Mohammad ◽  
Brian Volk ◽  
Keith McManus
Keyword(s):  
Flame Temperature ◽  
Operating Conditions ◽  
Published Data ◽  
Inlet Temperature ◽  
Combustion System ◽  
Combustion Emissions ◽  
Exit Temperature ◽  
Combustion Systems ◽  
Secondary Air ◽  
The Impact

Abstract It is a common practice to relate emissions performance of Dry Low Emissions (DLE) combustion systems to the flame temperature that is estimated from the mass flows of air and fuel flowing through the premixer. In many combustion systems, the exit temperature (or turbine nozzle inlet temperature) is quite low and is not a good parameter for estimating combustion emissions. The difference between the combustion flame temperature and exit temperature is mainly due to secondary air dilution. To our knowledge there are no detailed published data that quantify the impact of this temperature difference on combustion emissions. The target of this study is to quantify the impact of secondary air variation on emissions, both globally and locally. High pressure experiments are conducted at H class gas turbine operating conditions using a DLE combustion system. In the context of this DLE system, secondary air refers to cooling and leakage flows because direct air dilution of the combustion gasses is not necessary. This is because the flame stabilized downstream of the premixer is well mixed and fuel-lean. With NOx requirements moving toward single digit (ppm) levels, it becomes essential to accurately quantify the impact of reducing the secondary air percentage on emissions performance. In addition to the need to carefully study the impact of local interaction of the secondary air with the flame. The combustion system is configured with two independently controlled mixers along with a variable secondary air circuit that can change the secondary air fraction from 14 to 8%. Multiple emissions rakes are used at the combustor exit to delineate the interaction and relate it to the flame structure. The system is configured to enable sampling from individual rakes to study local emissions and the rakes can be ganged together to measure the bulk-averaged combustion emissions. This research provides a quantification of the improvement of the NOx margin with a decrease in the secondary air percentage. The study shows that the increase in margin is not a simple re-estimate of the combustor emissions using the NOx design curve due to flame quenching effects. The results also show that the secondary air can be used to improve the NOx emissions via controlling the interaction with the primary flame. The impact is quantified in terms of emissions, acoustics and metal temperatures.

scholarly journals Impact of the Flameholder Heat Conductivity on Combustion Instability Characteristics

2012 ◽  
Author(s):  
Seunghyuck Hong ◽  
Santosh J. Shanbhogue ◽  
Ahmed F. Ghoniem
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Stainless Steel ◽  
Dynamic Stability ◽  
Atmospheric Pressure ◽  
Dynamic Pressure ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Flame Holder ◽  
The Impact

In this paper, we investigate the impact of heat transfer between the flame and the flame-holder on the dynamic stability characteristics in a 50-kW backward facing step combustor. We conducted tests where we use a backward step block made of two different materials: ceramic and stainless steel whose thermal conductivities are 1.06 and 12 W/m/K, respectively. A set of experiments was conducted using a propane/air mixture at Re = 6500 for the inlet temperature of 300–500 K at atmospheric pressure. We measure the dynamic pressure and flame chemiluminescence to examine distinct stability characteristics using each flame-holder material over a range of operating conditions. We find that for tests with a flame-holder made of ceramic, the onset of instability is significantly delayed in time and, for certain operating conditions, disappears altogether. Stated differently, for certain operating conditions, the combustor can be stabilized by reducing the thermal conductivity of the flame-holder. As the thermal conductivity of the flame-holder increases, the combustor becomes increasingly unstable over a range of operating conditions. These results imply that the dynamic stability characteristics depend strongly on the heat transfer between the flame and the combustor wall near the flame anchoring region.

Influence of Pre-Flame and Post-Flame Mixing on NOx-Formation in a Reacting Premixed Jet in Hot Cross Flow

2015 ◽  
Author(s):  
Denise Ahrens ◽  
Michael Kolb ◽  
Christoph Hirsch ◽  
Thomas Sattelmayer
Keyword(s):  
Large Scale ◽  
Nox Reduction ◽  
Flame Temperature ◽  
Cross Flow ◽  
Inlet Temperature ◽  
Nox Formation ◽  
Second Stage ◽  
Turbine Inlet ◽  
Lift Off ◽  
The Impact

Axial staging in premixed gas turbine combustors is a promising option for the increase of firing temperature without NOx-penalty and for the improvement of turndown ratio, which is limited by the onset of CO-emissions. The configuration of greatest interest is the combination of state of the art premixed combustion in the primary stage with secondary injectors near the turbine inlet, which feed additional jets of premixed combustible mixture into the hot cross flow. Regarding NOx this configuration is particularly beneficial (1) if the overall mixing quality in the first stage is limited, (2) if the difference between primary zone flame temperature and turbine inlet temperature due to air addition along the combustor is large and (3) if a high degree of mixing in the second stage is achieved. The potential of this promising combustion concept was investigated in a large scale atmospheric test rig. For the study presented below scaling of the second stage according to Karlovitz number similarity was chosen. This leads to smaller jet diameters and higher injection velocities compared to scaling based on Damköhler number applied in an earlier study. The impact of the higher velocities at the injector outlet on the flow field, on the lift-off height of the flame and on NOx-formation is analyzed. A chemical network model is presented, which illustrates the effects of pre-flame and post-flame mixing on NOx-formation under atmospheric and high pressure conditions. In addition this model is used to study the interactions of chemistry with mixing between the reacting jet and cross flow. On the basis of atmospheric testing and reactor modeling, predictions for engine pressure are made assuming similar lift-off as well as pre- and post-flame mixing. These results are further analyzed regarding the NOx-reduction potential at different equivalence ratios and residence times. Finally, it is discussed under which conditions the investigated configuration can be beneficially applied to reduce NOx-emissions of real engines.

scholarly journals Design and Experimentation of a Combustor for High Combustion Intensity

1985 ◽  
Author(s):  
André Mestre ◽  
Anne Cadiou
Keyword(s):  
Short Duration ◽  
Atmospheric Pressure ◽  
Gas Turbines ◽  
Combustion Zone ◽  
Combustion Efficiency ◽  
Direct Visualization ◽  
Pressure Losses ◽  
Loading Parameter ◽  
Technical Solutions

The length and volume requirements of small gas turbines for missiles or propelled targets lead to combustor designs with high combustion intensity and large value of the air loading parameter Ω. The conventional combustors have used conditions corresponding to Ω values in the 1 to 10 kg m−3s−1 range. The increase of Ω required for combustors in missiles conduces for existing liners to a decrease of combustion efficiency and to an increase of pressure losses. Technical solutions have been worked out to make a combustor operating with a large air loading parameter: 25kgm-3s-1⩽Ω⩽50kgm-3s-1 and a correct combustion efficiency (η = 0.955). Test performed at atmospheric pressure with direct visualization of the combustion zone has shown a uniform primary flame and a moderately heated liner that can withstand short duration flights.

Influence of Preflame and Postflame Mixing on NOx Formation in a Reacting Premixed Jet in Hot Cross Flow

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
Denise Ahrens ◽  
Michael Kolb ◽  
Christoph Hirsch ◽  
Thomas Sattelmayer
Keyword(s):  
Large Scale ◽  
Nox Reduction ◽  
Flame Temperature ◽  
Cross Flow ◽  
Combustible Mixture ◽  
Inlet Temperature ◽  
Nox Formation ◽  
Second Stage ◽  
Turbine Inlet ◽  
The Impact

Axial staging in premixed gas turbine combustors is a promising option for the increase in firing temperature without NOx penalty and for the improvement of turndown ratio, which is limited by the onset of CO-emissions. The configuration of greatest interest is the combination of state of the art premixed combustion in the primary stage with secondary injectors near the turbine inlet, which feed additional jets of premixed combustible mixture into the hot cross flow. Regarding NOx, this configuration is particularly beneficial (1) if the overall mixing quality in the first stage is limited, (2) if the difference between primary zone flame temperature and turbine inlet temperature due to air addition along the combustor is large, and (3) if a high degree of mixing in the second stage is achieved. The potential of this promising combustion concept was investigated in a large scale atmospheric test rig. For the study presented below, scaling of the second stage according to Karlovitz number similarity was chosen. This leads to smaller jet diameters and higher injection velocities compared to scaling based on Damköhler number applied in an earlier study. The impact of the higher velocities at the injector outlet on the flow field, on the liftoff height of the flame and on NOx formation is analyzed. A chemical network model is presented, which illustrates the effects of preflame and postflame mixing on NOx formation under atmospheric and high pressure conditions. In addition, this model is used to study the interactions of chemistry with mixing between the reacting jet and cross flow. On the basis of atmospheric testing and reactor modeling, predictions for engine pressure are made assuming similar liftoff as well as pre and postflame mixing. These results are further analyzed regarding the NOx reduction potential at different equivalence ratios and residence times. Finally, it is discussed under which conditions the investigated configuration can be beneficially applied to reduce NOxemissions of real engines.

Model estimates of the results of diabetes patients using modern glucometers with tri-color technology for displaying test results

2019 ◽  
pp. 81-89
Author(s):  
Larisa Dmitrievna Popovich ◽  
Svetlana Valentinovna Svetlichnaya ◽  
Aleksandr Alekseevich Moiseev
Keyword(s):  
Diabetes Mellitus ◽  
Type 2 Diabetes ◽  
Type 1 Diabetes ◽  
Economic Benefits ◽  
Test Results ◽  
Self Monitoring ◽  
Patients With Diabetes ◽  
The Impact

Diabetes – a disease in which the effect of the treatment substantially depends on the patient. Known a study showed that the use of glucometers with the technology of three-color display of test results facilitates self-monitoring of blood sugar and leads to a decrease in glycated hemoglobin (HbAlc). Purpose of the study: to modeling the impact of using of a glucometer with a color-coded display on the clinical outcomes of diabetes mellitus and calculating, the potential economic benefits of reducing the hospitalization rate of patients with diabetes. Material and methods. Based on data from two studies (O. Schnell et al. and M. Baxter et al.) simulation of the reduction in the number of complications with the use of a glucometer with a color indication. In a study by O. Schnell et al. a decrease of HbA1c by 0.69 percent is shown when using the considered type of glucometers, which was the basis of the model. Results. In the model, the use of a glucometer with a color-coded display for type 1 diabetes led to a decrease in the total number of complications by 9.2 thousand over 5 years per a cohort of 40 thousand patients with different initial levels of HbA1c. In a cohort of 40 thousand patients with type 2 diabetes, the simulated number of prevented complications was 1.7 thousand over 5 years. When extrapolating these data to all patients with diabetes included in the federal register of diabetes mellitus (FRD), the number of prevented complications was 55.4 thousand cases for type 1 diabetes and 67.1 thousand cases for type 2 diabetes. The possible economic effect from the use of the device by all patients with a diagnosis of diabetes, which are included in the FRD, estimated at 1.5 billion rubles for a cohort of patients with type 1 diabetes and 5.3 billion rubles for patients with type 2 diabetes. Conclusion. Improving the effectiveness of self-monitoring, which is the result of the use of glucometers with color indicators, can potentially significantly reduce the incidence of complications in diabetes and thereby provide significant economic benefits to society.

Do hotel industry operations deteriorate air quality?

2021 ◽  
pp. 135481662110224
Author(s):  
Liang-Ju Wang ◽  
Ming-Hsiang Chen ◽  
Zhandong Yang ◽  
Ching-Hui (Joan) Su
Keyword(s):  
Air Quality ◽  
Hotel Industry ◽  
Second Step ◽  
Test Results ◽  
Sales Revenue ◽  
Key Indicator ◽  
Regression Test ◽  
Rolling Regression ◽  
The Impact ◽  
Regression Tests

This study proposes and tests two hypotheses concerning the effects of hotel industry operations on air quality based on data of 26 major tourist cities in China from 2002 to 2017. The empirical analyses take two steps. In the first step, panel regression test results reveal that hotel industry operations (measured by hotel sales revenue) significantly raise the value of particulate matter (PM)2.5 (the key indicator of air quality), supporting the first hypothesis that hotel industry operations deteriorate air quality and providing empirical evidence of the adverse impact of the hotel industry on air quality. In the second step, subsample analyses support the second hypothesis that the impact of hotel sales revenue on air quality diminishes over time. The results from the rolling regression tests validate the existence of a diminishing effect of hotel industry operations on air quality.

scholarly journals Viscoelastic Properties of Cell Structures Manufactured Using a Photo-Curable Additive Technology—PJM

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1895
Author(s):  
Tomasz Kozior ◽  
Czesław Kundera
Keyword(s):  
Viscoelastic Properties ◽  
Cellular Structure ◽  
Material Selection ◽  
Cellular Structures ◽  
Test Results ◽  
Additive Technology ◽  
Polymer Resin ◽  
Cell Structures ◽  
Relaxation Curves ◽  
The Impact

This research paper reviews the test results involving viscoelastic properties of cellular structure models made with the PolyJet Matrix—PJM additive technology. The designed test specimens were of complex cellular structure and made of three various photo-curable polymer resin types. Materials were selected taking into account the so-called “soft” and “tough” material groups. Compressive stress relaxation tests were conducted in accordance with the recommendations of standard ISO 3384, and the impact of the geometric structure shape and material selection on viscoelastic properties, as well as the most favorable geometric variants of the tested cellular structure models were determined. Mathematica and Origin software was used to conduct a statistical analysis of the test results and determine five-parameter functions approximating relaxation curves. The most favorable rheological was adopted and its mean parameters determined, which enables to match both printed model materials and their geometry in the future, to make a component with a specific rheological response. Furthermore, the test results indicated that there was a possibility of modelling cellular structures within the PJM technology, using support material as well.

Simulation of an Acid Gas Removal Unit Using a DGA and MDEA Blend Instead of a Single Amine

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Umer Zahid
Keyword(s):  
Energy Savings ◽  
Circulation Rate ◽  
Inlet Temperature ◽  
Acid Gas ◽  
Gas Processing ◽  
Gas Removal ◽  
Processing Plants ◽  
Operational Energy ◽  
Commercial Process ◽  
The Impact

AbstractMost of the industrial acid gas removal (AGR) units employ chemical absorption process for the removal of acid gases from the natural gas. In this study, two gas processing plants operational in Saudi Arabia have been selected where two different amines n1amely, diglycolamine (DGA) and monoethanol amine (MDEA) are used to achieve the sweet gas purity with less than 4 ppm of H2S. This study performed a feasibility simulation of AGR unit by utilizing the amine blend (DGA+MDEA) for both plants instead of a single amine. The study used a commercial process simulator to analyze the impact of process variables such as amine circulation rate, amine strength, lean amine temperature, regenerator inlet temperature, and absorber and regenerator pressure on the process performance. The results reveal that when the MDEA (0–15 wt. %) is added to DGA, marginal energy savings can be achieved. However, significant operational energy savings can be made when the DGA (0–15 wt. %) is blended with MDEA being the main amine.

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