Experimental and Numerical Investigations in a Gas-Fired Boiler With Combustion Stabilizing Device

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Zhengming Yi ◽  
Zheng Zhou ◽  
Qian Tao ◽  
Zhiwei Jiang
Keyword(s):  
Heat Exchange ◽  
Combustion Process ◽  
Side Surface ◽  
Coke Oven ◽  
Combustion Stability ◽  
Nox Emissions ◽  
Gas Temperature ◽  
Safety And Reliability ◽  
Set Up ◽  
Exhaust Gas Temperature

The combustion stability has a significant influence on safety and reliability of a gas-fired boiler. In this study, a numerical model was first established and validated to investigate the effect of combustion stabilizing device on flow and combustion characteristics of 75 t/h blast furnace gas (BFG) and coke oven gas (COG) mixed-fired boiler. The results indicated that the device coupled with four corner burners enables the flame to spin upward around its side surface, which facilitates heat exchange between BFG and the device. Under stable combustion condition, the combustion stabilizing device can be used as a stable heat source and enhance heat exchange in the furnace. Then, to obtain optimal COG ratio, combustion process of different blending ratios were experimentally investigated. The experimental results revealed that the energy loss due to high exhaust gas temperature is relatively high. COG ratio should be set up taking into account both boiler efficiency and NOX emissions. When COG blending ratio is maintained about 20%, the thermal efficiency of the boiler is 88.84% and the NOX concentration is 152 mg/m3 at 6% O2, meeting NOX emissions standard for the gas boiler.

scholarly journals Experimental investigation of V-gutter flameholders

2017 ◽  
Vol 21 (2) ◽  
pp. 1011-1019 ◽  
Author(s):  
Dias Umyshev ◽  
Abay Dostiyarov ◽  
Musagul Tumanov ◽  
Quiwang Wang
Keyword(s):  
Bluff Body ◽  
Combustion Process ◽  
Combustion Efficiency ◽  
Bluff Bodies ◽  
Nox Emissions ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Flame Holder ◽  
Efficiency Increase ◽  
Exhaust Gas Temperature

Combustion characteristics and NOx emissions of propane and air mixture in a channel with a bluff body were investigated experimentally. Effects of the angle and type of the flameholder on the NOx emissions, blow-off limit, combustion efficiency, and exhaust gas temperature were examined. The results show that the NOx emissions are dependent on flameholder type and angle. Also it was observed that the perforated V-gutters considerably increases the blow-off performance. Moreover, the blow-off limit decreases as the geometrical size of flame-holder is increased. In addition, the combustion efficiency increase first and then decrease with the increase of the angle. The physics of the combustion process behind V-gutter flameholdes has been discussed. On the basis of experiment authors presented a modified version of the formula for calculation of lean blow-off limits when using bluff bodies, such as V-gutter flameholders.

Comparison of Numerical Combustion Models for Hydrogen and Hydrogen-Rich Syngas Applied for Dry-Low-NOx-Micromix-Combustion

2016 ◽  
Author(s):  
H. H.-W. Funke ◽  
N. Beckmann ◽  
J. Keinz ◽  
S. Abanteriba
Keyword(s):  
Reaction Mechanism ◽  
Gas Turbines ◽  
Combustion Process ◽  
Computational Effort ◽  
Hydrogen Combustion ◽  
Combustion Stability ◽  
Research Approach ◽  
Pure Hydrogen ◽  
Nox Emissions ◽  
Combustion Models

The Dry-Low-NOx (DLN) Micromix combustion technology has been developed as low emission combustion principle for industrial gas turbines fueled with hydrogen or syngas. The combustion process is based on the phenomenon of jet-in-crossflow-mixing. Fuel is injected perpendicular into the air-cross-flow and burned in a multitude of miniaturized, diffusion-like flames. The miniaturization of the flames leads to a significant reduction of NOx emissions due to the very short residence time of reactants in the flame. In the Micromix research approach, CFD analyses are validated towards experimental results. The combination of numerical and experimental methods allows an efficient design and optimization of DLN Micromix combustors concerning combustion stability and low NOx emissions. The paper presents a comparison of several numerical combustion models for hydrogen and hydrogen-rich syngas. They differ in the complexity of the underlying reaction mechanism and the associated computational effort. For pure hydrogen combustion a one-step global reaction is applied using a hybrid Eddy-Break-up model that incorporates finite rate kinetics. The model is evaluated and compared to a detailed hydrogen combustion mechanism derived by Li et al. including 9 species and 19 reversible elementary reactions. Based on this mechanism, reduction of the computational effort is achieved by applying the Flamelet Generated Manifolds (FGM) method while the accuracy of the detailed reaction scheme is maintained. For hydrogen-rich syngas combustion (H2-CO) numerical analyses based on a skeletal H2/CO reaction mechanism derived by Hawkes et al. and a detailed reaction mechanism provided by Ranzi et al. are performed. The comparison between combustion models and the validation of numerical results is based on exhaust gas compositions available from experimental investigation on DLN Micromix combustors. The conducted evaluation confirms that the applied detailed combustion mechanisms are able to predict the general physics of the DLN-Micromix combustion process accurately. The Flamelet Generated Manifolds method proved to be generally suitable to reduce the computational effort while maintaining the accuracy of detailed chemistry. Especially for reaction mechanisms with a high number of species accuracy and computational effort can be balanced using the FGM model.

A New Approach for Ignition Timing Correction in Spark Ignition Engines Based on Cylinder Tendency to Surface Ignition

2016 ◽  
Vol 819 ◽  
pp. 272-276 ◽  
Author(s):  
Ali Ghanaati ◽  
Mohd Farid Muhamad Said ◽  
Intan Zaurah Mat Darus ◽  
Amin Mahmoudzadeh Andwari
Keyword(s):  
Spark Ignition ◽  
Combustion Stability ◽  
Spark Ignition Engines ◽  
Gas Temperature ◽  
New Approach ◽  
Surface Ignition ◽  
Spark Plug ◽  
Engine Combustion ◽  
Si Engines ◽  
Exhaust Gas Temperature

The performance of Spark Ignition (SI) engines in terms of thermal efficiency can be restricted by knock. Although it is common for all SI engines to exhibit knock from compressed end-gas, knocks from surface ignition remains a more serious problem due to its effect on combustion stability and its obscurity to detect. This paper focuses on predicting the occurrence of knocks from surface ignition by monitoring exhaust gas temperature (EGT). EGT measured during an engine cycle without the spark plug firing. Therefore, EGT rises illustrated any combustion made by surface ignition. Modelling and simulation of a one-dimensional engine combustion done by using GT-Power. The new approach reduces the complexity as EGT monitoring does not require high computational demands, and the EGT signals are robust to noise. The method is validated against a variety of fuel properties and across engine conditions. A new approach is proposed as a measure to predict and detect the knock events.

scholarly journals Experimental investigation of distance between v-gutters on flame stabilization and NOx emissions

2019 ◽  
Vol 23 (5 Part B) ◽  
pp. 2971-2981 ◽  
Author(s):  
Dias Umyshev ◽  
Abay Dostiyarov ◽  
Andrey Kibarin ◽  
Galya Tyutebayeva ◽  
Gaziza Katranova ◽  
...  
Keyword(s):  
Bluff Body ◽  
Flame Stabilization ◽  
Temperature Fields ◽  
Flame Stability ◽  
Bluff Bodies ◽  
Nox Emissions ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Inlet Velocity ◽  
Exhaust Gas Temperature

Blow-off performance and NOx emissions of the propane and air mixture in a rectangular combustion chamber with bluff bodies were investigated experimentally and numerically. The effects of distance between bluff bodies on NOx emissions, the blow-off limit, and exhaust gas temperature were examined. It was observed that NOx emissions are highly dependent on distance between V-gutters. The re-circulation zone behind the bluff body expands in width based on the decrease of distance between V-gutters, and expands in length with the increase of inlet velocity. The temperature fields behind the bluff body show a similar change, the temperature behind the bluff body reaches its highest when the distance between V-gutters reaches 20 mm, meaning it has better flame stability. The blow-off limit is significantly improved with the decrease of distance between V-gutters. The blow-off limit is greatly improved by reducing the distance between the V-gutters. Maximum blow-off limit of 0.11 is reached in the case of 20 mm, compared with 0.16 at 50 mm at a speed of 10 m/s.

Effect of Cavity Coupling Factors of Opposed Counter-Flow Microcombustor on the Methane-Fueled Catalytic Combustion Characteristics

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Yunfei Yan ◽  
Ying Liu ◽  
Haojie Li ◽  
Weipeng Huang ◽  
Yanrong Chen ◽  
...  
Keyword(s):  
Methane Conversion ◽  
Catalytic Combustion ◽  
Maximum Velocity ◽  
Combustion Efficiency ◽  
Geometric Parameters ◽  
Combustion Stability ◽  
Gas Temperature ◽  
Counter Flow ◽  
Inlet Velocity ◽  
Exhaust Gas Temperature

In this work, numerical investigations of methane catalytic combustion in the opposed counter-flow microcombustor are conducted under various inlet velocities, equivalence ratios, and geometric parameters. The results indicate that the high temperature zone is mainly located at the front and middle parts of the reaction zone. With the increase of inlet velocity, both methane conversion and exhaust gas temperature decrease, while the methane concentration in the downstream area increases. Its maximum velocity limit is 2.9 m/s. Moreover, temperature step zones of opposed counter-flow are obviously located at the front and middle parts with different equivalence ratios. The combustion efficiency decreases slowly with the increase of equivalence ratios. More importantly, critical values about the geometric parameters are determined for keeping better thermal performance. It is concluded that inlet velocity limit and methane conversion rate can be significantly increased and the temperature distribution is more uniform via reducing inlet width L2 and inlet height H, increasing the length of the downstream parts L1 and the downstream entrance length L3. In general, the opposed counter-flow microcombustor with optimized structure has better combustion stability. This design offers another way for developing the opposed counter-flow microcombustor.

Improved Lazy Learning Based Dynamic Modeling Method on Combustion Process

2011 ◽  
Vol 52-54 ◽  
pp. 680-685
Author(s):  
Qi Lei ◽  
Min Wu ◽  
Chun Sheng Wang
Keyword(s):  
Dynamic Modeling ◽  
Combustion Process ◽  
Coke Oven ◽  
Modeling Method ◽  
Local Model ◽  
Lazy Learning ◽  
Angle Measure ◽  
Sample Data ◽  
Change Trend ◽  
Set Up

This paper presents a new data-based method for the industrial combustion process. In this method, angle measure, which presents change trend of samples, is introduced in evaluating the similarity between the sample data and query data, which is not exploited in the previous word. And ARX method is used to build the local model. With the moving of working points, different models are set up to realize the accurate modeling for combustion process. An example of coke oven combustion process is presented to illustrate the modeling capability of the proposed method.

Comparison of Numerical Combustion Models for Hydrogen and Hydrogen-Rich Syngas Applied for Dry-Low-Nox-Micromix-Combustion

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Harald H. W. Funke ◽  
Nils Beckmann ◽  
Jan Keinz ◽  
Sylvester Abanteriba
Keyword(s):  
Gas Turbines ◽  
Combustion Process ◽  
Cross Flow ◽  
Computational Effort ◽  
Combustion Stability ◽  
Research Approach ◽  
Nox Emissions ◽  
Efficient Design ◽  
Detailed Chemistry ◽  
Combustion Models

The Dry-Low-NOx (DLN) Micromix combustion technology has been developed as low emission combustion principle for industrial gas turbines fueled with hydrogen or syngas. The combustion process is based on the phenomenon of jet-in-crossflow-mixing (JICF). Fuel is injected perpendicular into the air-cross-flow and burned in a multitude of miniaturized, diffusion-like flames. The miniaturization of the flames leads to a significant reduction of NOx emissions due to the very short residence time of reactants in the flame. In the Micromix research approach, computational fluid dynamics (CFD) analyses are validated toward experimental results. The combination of numerical and experimental methods allows an efficient design and optimization of DLN Micromix combustors concerning combustion stability and low NOx emissions. The paper presents a comparison of several numerical combustion models for hydrogen and hydrogen-rich syngas. They differ in the complexity of the underlying reaction mechanism and the associated computational effort. The performance of a hybrid eddy-break-up (EBU) model with a one-step global reaction is compared to a complex chemistry model and a flamelet generated manifolds (FGM) model, both using detailed reaction schemes for hydrogen or syngas combustion. Validation of numerical results is based on exhaust gas compositions available from experimental investigation on DLN Micromix combustors. The conducted evaluation confirms that the applied detailed combustion mechanisms are able to predict the general physics of the DLN-Micromix combustion process accurately. The FGM method proved to be generally suitable to reduce the computational effort while maintaining the accuracy of detailed chemistry.

An Experimental Study on the Performance and Emission Characteristics of Jatropha Biodiesel Fuelled CI Engine

2009 ◽  
Author(s):  
Samiddha Palit ◽  
Bijan Kumar Mandal ◽  
Sudip Ghosh ◽  
Arup Jyoti Bhowal
Keyword(s):  
Diesel Fuel ◽  
Combustion Process ◽  
Maximum Efficiency ◽  
Emission Characteristics ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Biodiesel Blends ◽  
Full Load ◽  
Fuel Blends ◽  
Exhaust Gas Temperature

A twin cylinder, constant speed, direct injection CI (diesel) engine was run on jatropha biodiesel and diesel fuel blends. The engine was directly coupled to a hydraulic dynamometer whose load was varied by adjusting load wheel on the top of the engine. The test results were recorded for pure diesel, pure biodiesel (B100) and different diesel/biodiesel blends. The performance characteristics shows that brake specific fuel consumption (BSFC) decreases rapidly with increase of load up to 4.0 to 4.5 kW (55% to 62% of full load) and then decreases slowly. This result also indicates that BSFC increases when the percentage of biodiesel in the blends is increased. Brake thermal efficiency also increases from high biodiesel blends to pure diesel fuel. Each fuel curve shows maximum efficiency reaches at the load range of 5.0 to 5.5 kW (68% to 75% of full load). Pure diesel has maximum efficiency 29.6%, where as pure biodiesel has maximum efficiency of 21.2%. The exhaust gas temperature increases with the load for all fuel blends. Pure biodiesel gives higher exhaust temperature (320°C) than pure diesel (260°C). The exhaust gas temperature increases with the higher percentage of biodiesel blends in different fuel blends. The probable reason for that is biodiesel contains oxygen atoms which make the combustion process complete and hence more energy is released. In respect of emission characteristics, carbon mono-oxide (CO) and hydrocarbon emissions are improved with the addition of biodiesel to diesel. But these emissions increase with the increase of load for all fuel blends. NOx emission increases with load as well as percentage of blending of biodiesel in the diesel fuel.

Research on Exhaust Gas Temperature inside Catalytic Honeycomb Monolith Channel of Natural Gas Burner Start-up

2012 ◽  
Vol 621 ◽  
pp. 223-227 ◽  
Author(s):  
Zhi Hua Wang ◽  
Shi Hong Zhang
Keyword(s):  
Natural Gas ◽  
Gas Phase ◽  
Catalytic Combustion ◽  
Combustion Process ◽  
Pollutant Emissions ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Start Up ◽  
Honeycomb Monolith ◽  
Exhaust Gas Temperature

This article discussed exhaust gas temperature and pollutant emissions characteristics of the combustion of rich natural gas-air mixtures in Pd metal based honeycomb monoliths in burner during the period of start-up process. The burner need to be ignited by gas phase combustion with the excessive air coefficient (a) at 1.3. The experimental results in catalytic monolith can be explained from SPFR. In this experiment, exhaust gas temperature and pollutant emissions were measured by thermocouple K of diameter 0.5 and the analyser every 1 minute, respectively. The finding would be applied for industrial catalytic combustion process start-up.

scholarly journals Measurement of GT exhaust gas temperature by acoustic pyrometry: Preliminary error investigation

2021 ◽  
Vol 312 ◽  
pp. 11011
Author(s):  
Gianluca Caposciutti ◽  
Lorenzo Ferrari
Keyword(s):  
Acoustic Wave ◽  
Sound Propagation ◽  
Time Of Flight ◽  
Optimal Solution ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Acoustic Emitter ◽  
Set Up ◽  
Exhaust Gas Temperature ◽  
The Impact

Acoustic pyrometry is an interesting technique that may find several useful applications in turbomachinery. It is well known that the speed of sound in a medium is directly related to its temperature. Acoustic pyrometry estimates the temperature of a gas by considering the time of flight of an acoustic wave moving through it. If one acoustic emitter-receiver couple is used, only the average temperature along the acoustic path can be determined. If multiple emitter-receiver couples laying on the same plane are used, a reconstruction of the temperature map in the section is possible. In this last case, the analysis is based on the fact that the temperature of each sub portion of the section affects the time of flight of all the acoustic paths travelling across it. Many parameters affect the accuracy of the measurement. They are mainly related to the physic of the sound propagation in a medium, the accuracy of the instrumentation used, the interaction between the acoustic wave and the flow velocity and the hardware set-up. In this study, the impact of the measurement set up of an acoustic pyrometry for the measurement of the exhaust gas temperature in a gas turbine was investigated to determine the optimal solution in terms of accuracy and robustness to uncertainties.

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