Numerical Simulation of Turbulent Biogas Combustion

2007 ◽  
Author(s):  
Beibei Yan ◽  
Xuesong Bai ◽  
Guanyi Chen ◽  
Changye Liu
Keyword(s):  
Numerical Simulation ◽  
Mass Flow ◽  
Flame Temperature ◽  
Combustion Process ◽  
Methane Combustion ◽  
Operational Parameters ◽  
Heating Value ◽  
Air Supply ◽  
Methane Flame ◽  
Secondary Air

Operating parameters are considered important for the biogas combustion process and the resulted flame features. The paper investigated the influence of typical parameters through numerical simulation, which include the dimension of combustor, fuel and air mass flow, and secondary air supply. The results from the simulations show that the biogas combustion behaves, to some extent, similarly to the methane combustion, yet significant differences exist between their flames. The combustion process is fairly sensitive to the geometrical and operational parameters. Biogas flame temperature is even lower compared to the methane flame temperature because biogas contains CO2 resulting in low heating value, therefore it is not straightforward to obtain stable combustion. Preheated secondary air or reduced its mass flow may have to be used in this case.

Numerical Simulation of Combustion Process in a 350t/d MSW Incinerator

2012 ◽  
Vol 268-270 ◽  
pp. 898-901
Author(s):  
Shui E Yin ◽  
Jun Wu
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Combustion Process ◽  
Species Distributions ◽  
Complete Combustion ◽  
Operational Conditions ◽  
Furnace Outlet ◽  
Air Supply ◽  
Total Temperature ◽  
Secondary Air

A mathematical model was presented for the combustion of municipal solid waste in a 350t/d MSW-burning incinerator. Numerical simulations were performed to predict the temperature and the species distributions in the furnace, with practical operational conditions taken into account. When the total air supply is constant, reducing primary air and increasing secondary air properly results in the higher total temperature of the furnace and the more oxygen concentration at the furnace outlet, and thereby contributes to the complete combustion of combustibles so that an optimal combustion effect can be achieved.

scholarly journals Low Emissions Resulting from Combustion of Forest Biomass in a Small Scale Heating Device

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5495
Author(s):  
Karol Tucki ◽  
Olga Orynycz ◽  
Andrzej Wasiak ◽  
Antoni Świć ◽  
Leszek Mieszkalski ◽  
...  
Keyword(s):  
Combustion Process ◽  
The Other ◽  
Screw Conveyor ◽  
Small Scale ◽  
Heat Output ◽  
Maximum Heat ◽  
Heating Device ◽  
Air Supply ◽  
Low Emission ◽  
Secondary Air

The paper concerns the analysis of harmful emissions during the combustion process in households. The subject of the analysis is a low emission heating device with an output of 50 kW for burning biomass of forest origin (low-quality hardwoods or softwoods). The proposed boiler is automatically fed from the connected container by means of a screw conveyor. In this way, the optimum amount of fuel is supplied for maximum heat output (adjustment of the ratio of primary air to fuel). The proposed biomass heating system is equipped with a primary and secondary air supply system and exhaust gas sensors. This ensures optimal regulation of the air mixture and efficient and clean combustion. Proper control of the combustion process, control of the air supply by means of a lambda sensor and power control of the system ensure a low-emission combustion process. The system precisely adjusts to the heat demand. This results in highly efficient heating technology with low operating costs. In the presented work, the emission of exhaust gases from the proposed heating device during the combustion of woodchips and beech–oak pellets were measured. It is demonstrated that the proposed design of the boiler equipped with intelligent control significantly reduces emissions when the biomass solid fuels are used, e.g., CO emissions from beech and oak chips and pellets in the low-emission boiler—18 extract pipes shows the value <100 ppm, which is even lower than when gas is burned in the other boilers; on the other hand, the pine chips show even higher emission when burned in the low-emission burner. Consequently, the choice of biomass source and form of the fuel play some role in the emissions observed.

scholarly journals Investigations of combustion process in combined cooker-boiler fired on solid fuels

2006 ◽  
Vol 10 (4) ◽  
pp. 121-130
Author(s):  
Dragoslava Stojiljkovic ◽  
Vladimir Jovanovic ◽  
Milan Radovanovic ◽  
Nebojsa Manic ◽  
Ivo Radulovic
Keyword(s):  
Flue Gas ◽  
Combustion Process ◽  
Solid Fuels ◽  
Gas Temperature ◽  
Weight Changes ◽  
Complete Combustion ◽  
Air Supply ◽  
Class 1 ◽  
Secondary Air ◽  
Co Emission

The aim of the investigation was to make some reconstructions on the existing stove used for cooking and baking and to obtain the combined cooker-boiler which will fulfill the demands of European standard EN 12815. Implementation of modern scientific achievements in the field of combustion on stoves and furnaces fired on solid fuels was used. During the investigations four various constructions were made with different fresh air inlet and secondary air supply with the intention to obtain more complete combustion with increased efficiency and reduced CO emission. Three different fuels were used: firewood, coal, and wood briquette. A numerous parameters were measured: fuel weight changes during the combustion process, temperature of inlet and outlet water, flue gas composition (O2, CO, SO2, CO2, NOx), flue gas temperature, ash quantity etc. The result of the investigations is the stove with the efficiency of more than 75% - boiler Class 1 (according EN 12815) and CO emission of about 1% v/v. The results obtained during the measurements were used as parameters for modeling of combustion process. .

scholarly journals Aerodynamic Characteristics of the Combustion Process of Sawdust in a Vortex Furnace with Counter-Swirling Flows

2021 ◽  
pp. 68-78
Author(s):  
Rafael Dzhyoiev ◽  
◽  
Andrei Redko ◽  
Igori Redko ◽  
Iuryi Pivnenko ◽  
...  
Keyword(s):  
Numerical Study ◽  
Angular Rate ◽  
Combustion Process ◽  
Aerodynamic Characteristics ◽  
Vortex Furnace ◽  
Saw Dust ◽  
Air Supply ◽  
Air Flows ◽  
Secondary Air ◽  
Furnace Height

The aim of this work is to study the working processes of burning the low-quality fuels, namely, the saw dust in the swirling-type furnaces with an opposite twisted motion of the air. The goal was achieved using the physical and mathematical modeling of the flows interaction. The article presented the results of numerical study of aerodynamic characteristics of burning the saw dust in the swirling-type furnace with the opposite twisted air flows. For the research, the facility was used for the saw dust burning with the air supply into the lower and upper zones of burning. The most essential result of the work was modeling of the working process at the ratio of the flows of the primary air and secondary air without the fuel admixture, equal to 0.2. The tangential rate of the flow changed according to the horizontal sections from 3-5 m/s to 40-42 m/s and with respect to the furnace height from 51 m/s to 30 m/s. The average angular rate of the mixture changed relatively the furnace height in the ranges of 171-500 l/s to 100—300 l/s. The significance of the results obtained consists in determination of the possibility of increasing the efficiency of the work of the furnace facilities at the expense of the introduction of the primary and secondary air flows. In this situation, the optimal ratio of consumptions of primary and secondary air was 0.2. Thus, in this work the consumption of primary air was 1.285 kg/s, the consumption of the secondary air was 0.255 kg/s.

Prediction of Flow and Combustion Characteristics for a Gas Turbine Combustor Burning Low Heating Value Fuel

2010 ◽  
Author(s):  
M. R. Shaalan ◽  
H. A. El Salmawy ◽  
M. Anwar Ismail
Keyword(s):  
Gas Turbine ◽  
Performance Indicators ◽  
Substantial Reduction ◽  
Combustion Characteristics ◽  
Swirl Ratio ◽  
Operational Parameters ◽  
Gas Turbine Combustor ◽  
Heating Value ◽  
Secondary Air ◽  
The Impact

In this study, a numerical model has been developed to simulate the flow and combustion in a gas turbine combustor of type (Winnox-TUD-Combustor), which burns low heating value gas. The model relies on the computational code “FLUENT”. This code has been used to solve the governing equations. The characteristics of the model are; steady, turbulent, two dimensional, axisymmetric and swirling flow. The combustion process has been simulated as non-premixed combustion. The study includes the impact of several design and operational parameters on the characteristics of the flow and combustion inside the combustion chamber. These parameters include; ratio of secondary to primary air, ratio of tertiary to primary air, swirl ratio, number of inlets of the secondary air and their direction. Four performance indicators have been used to evaluate the impact of the aforementioned design and operating parameters. These indicators include; average temperature of the exhaust gases to the turbine, specific NOx emission, pattern factor and combustion efficiency of the combustor. In order to identify the optimum values of the aforementioned design and operational parameters, Artificial Neural Network (ANN) technique has been utilized to enrich the output results. This facilitates searching for the optimum values of the aforementioned parameters. Furthermore the effect of the variations in fuel composition on the combustion characteristics and accordingly on the performance indicators has been studied. It has been found that, all the studied parameters affect the performance of the combustor to a certain extent. However, fuel swirl ratio, primary to secondary air ratio and tertiary to primary air ratio as well as carbon monoxide to hydrogen ratio in the fuel are the controlling factors. Optimizing these parameters can lead to a substantial reduction in specific NOx emissions down to 4.0 gm/kg of fuel. Also an improvement in pattern factor to values below 0.3 has been achieved.

Combustion Process Analysis and Diagnostic Using Optical Flame Scanners in Front-Fired Pulverized Coal Boiler

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Daniel Nabagło ◽  
Teresa Kurek ◽  
Konrad Wojdan
Keyword(s):  
Power Plants ◽  
Process Analysis ◽  
Flame Temperature ◽  
Combustion Process ◽  
Complete Information ◽  
Pulverized Coal ◽  
Optical Parameters ◽  
Research Activity ◽  
Burner Flame ◽  
Secondary Air

The paper presents a novel concept and method of coal combustion process analysis using flame scanners supervision system. The combustion process analysis and diagnostic has a crucial influence on boiler effectiveness, especially in high variance of load demand, which is nowadays a top challenge for coal-fired power plants. The first indicator of combustion inefficiency is flame stability, which can be observed as variation of flame intensity. Nowadays, there are no validated measuring methods dedicated for industrial usage, which are able to give complete information about flame condition. For this reason, the research activity was launched and focused on usage of commercial flame scanners for fast combustion analysis based on on-line flame parameters measuring. The analysis of combustion process was performed for 650 t/h live steam power boiler, which is supplied by five coal mill units. Each coal mill supplies four pulverized coal burners pulverized fuel ((PF) burners). The boiler start-up installation consists of 12 heavy oil burners placed in PF burners equipped with individual supervisory system based on Paragon 105f-1 flame scanners, which gave the possibility to observe and analyze the PF burner flame and oil burner flame individually. The research included numerous tests in which the combustion conditions inside the combustion chamber were changed. During stable load of selected mills, the primary air flow, secondary air dampers, air–coal mixture temperature, and balance were changed. The results of the changes were observed by flame scanners and the available optical parameters of the flame were analyzed: power spectral density, average amplitude (AA) of flame fluctuation, and flame temperature.

Effect of pre-swirl nozzle closure modes on unsteady flow and heat transfer characteristics in a pre-swirl system of aero-engine

2021 ◽  
pp. 095441002110191
Author(s):  
Gaowen Liu ◽  
Zhao Lei ◽  
Aqiang Lin ◽  
Qing Feng ◽  
Yan Chen
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Temperature Drop ◽  
Thermodynamic Characteristics ◽  
Circumferential Direction ◽  
Temperature Changes ◽  
Air Supply ◽  
Cooling Air

The pre-swirl system is of great importance for temperature drop and cooling air supply. This study aims to investigate the influencing mechanism of heat transfer, nonuniform thermodynamic characteristics, and cooling air supply sensitivity in a pre-swirl system by the application of the flow control method of the pre-swirl nozzle. A novel test rig was proposed to actively control the supplied cooling air mass flow rate by three adjustable pre-swirl nozzles. Then, the transient problem of the pre-swirl system was numerically conducted by comparison with 60°, 120°, and 180° rotating disk cavity cases, which were verified with the experiment results. Results show that the partial nozzle closure will aggravate the fluctuation of air supply mass flow rate and temperature. When three parts of nozzles are closed evenly at 120° in the circumferential direction, the maximum value of the nonuniformity coefficient of air supply mass flow rate changes to 3.1% and that of temperature changes to 0.25%. When six parts of nozzles are closed evenly at 60° in the circumferential direction, the maximum nonuniformity coefficient of air supply mass flow rate changes to 1.4% and that of temperature changes to 0.20%. However, different partial nozzle closure modes have little effect on the average air supply parameters. Closing 14.3% of the nozzle area will reduce the air supply mass flow rate by 9.9% and the average air supply temperature by about 1 K.

scholarly journals Comprehensive Thermodynamic Analysis of the Humphrey Cycle for Gas Turbines with Pressure Gain Combustion

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3521 ◽  
Author(s):  
Panagiotis Stathopoulos
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Combustion Process ◽  
Ideal Gas ◽  
Point Of View ◽  
Pressure Gain Combustion ◽  
Combustion Technology ◽  
Secondary Air ◽  
And Performance ◽  
The Impact

Conventional gas turbines are approaching their efficiency limits and performance gains are becoming increasingly difficult to achieve. Pressure Gain Combustion (PGC) has emerged as a very promising technology in this respect, due to the higher thermal efficiency of the respective ideal gas turbine thermodynamic cycles. Up to date, only very simplified models of open cycle gas turbines with pressure gain combustion have been considered. However, the integration of a fundamentally different combustion technology will be inherently connected with additional losses. Entropy generation in the combustion process, combustor inlet pressure loss (a central issue for pressure gain combustors), and the impact of PGC on the secondary air system (especially blade cooling) are all very important parameters that have been neglected. The current work uses the Humphrey cycle in an attempt to address all these issues in order to provide gas turbine component designers with benchmark efficiency values for individual components of gas turbines with PGC. The analysis concludes with some recommendations for the best strategy to integrate turbine expanders with PGC combustors. This is done from a purely thermodynamic point of view, again with the goal to deliver design benchmark values for a more realistic interpretation of the cycle.

Numerical Simulation of the Performance of an Axial Compressor Operating With Supercritical Carbon Dioxide

2018 ◽  
Author(s):  
Jinlan Gou ◽  
Wei Wang ◽  
Can Ma ◽  
Yong Li ◽  
Yuansheng Lin ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Numerical Simulation ◽  
Supercritical Carbon Dioxide ◽  
Critical Point ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Axial Compressor ◽  
Brayton Cycle ◽  
Supercritical Carbon

Using supercritical carbon dioxide (SCO2) as the working fluid of a closed Brayton cycle gas turbine is widely recognized nowadays, because of its compact layout and high efficiency for modest turbine inlet temperature. It is an attractive option for geothermal, nuclear and solar energy conversion. Compressor is one of the key components for the supercritical carbon dioxide Brayton cycle. With established or developing small power supercritical carbon dioxide test loop, centrifugal compressor with small mass flow rate is mainly investigated and manufactured in the literature; however, nuclear energy conversion contains more power, and axial compressor is preferred to provide SCO2 compression with larger mass flow rate which is less studied in the literature. The performance of the axial supercritical carbon dioxide compressor is investigated in the current work. An axial supercritical carbon dioxide compressor with mass flow rate of 1000kg/s is designed. The thermodynamic region of the carbon dioxide is slightly above the vapor-liquid critical point with inlet total temperature 310K and total pressure 9MPa. Numerical simulation is then conducted to assess this axial compressor with look-up table adopted to handle the nonlinear variation property of supercritical carbon dioxide near the critical point. The results show that the performance of the design point of the designed axial compressor matches the primary target. Small corner separation occurs near the hub, and the flow motion of the tip leakage fluid is similar with the well-studied air compressor. Violent property variation near the critical point creates troubles for convergence near the stall condition, and the stall mechanism predictions are more difficult for the axial supercritical carbon dioxide compressor.

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