Simulation Analysis of the System Integrating Oxy-Fuel Combustion and Char Gasification

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Ruochen Liu ◽  
Martin Graebner ◽  
Remi Tsiava ◽  
Ting Zhang ◽  
Shenqi Xu
Keyword(s):  
Flue Gas ◽  
Simulation Analysis ◽  
Co2 Reduction ◽  
Biomass Gasification ◽  
Integrated System ◽  
Char Gasification ◽  
Gasification Process ◽  
The Government ◽  
Gas Recirculation ◽  
The Impact

Abstract To explore the feasibility of converting hot flue gas into valuable syngas through char gasification process, Aspen Plus is applied to evaluate the performance of the integrated system including oxy-combustion, pyrolysis, gasification, and flue gas recirculation. The impact of feedstock type (reed straw and municipal solid waste (MSW)), feeding rate (0.1–1 t/h), and flue gas recycle ratio (FGR) (10%–30%) is investigated. The economic analysis of the integrated system is also performed. The results indicate that higher oxygen consumption is required for biomass gasification to reach the same temperature as MSW gasification. The gasification temperature is 750 °C–950 °C under 10%–30% FGR. The CO + H2 content in syngas from biomass gasification is slightly higher than that from MSW gasification. For the integrated system, more natural gas (NG) can be saved and more fossil CO2 can be reduced under biomass gasification. When the feedstock input is 1 t/h, the fossil CO2 emission can be reduced by 70% when taking biomass, the CO2 reduction is double of that when taking MSW. The total OPEX cost can be 26% saved by biomass and 62% saved by MSW due to the government subsidy. If CO2 tax is considered, the advantage of biomass for saving OPEX cost will be more obvious.

Modelling the Effect of External Flue Gas Recirculation on NOx and CO Emissions in a Premixed Gas Turbine Combustor With Chemical Reactor Networks

2018 ◽  
Author(s):  
V. Prakash ◽  
J. Steimes ◽  
D. J. E. M. Roekaerts ◽  
S. A. Klein
Keyword(s):  
Gas Turbine ◽  
Flue Gas ◽  
Recirculation Zone ◽  
Chemical Reactor ◽  
Inlet Temperature ◽  
Part Load ◽  
Flue Gas Recirculation ◽  
Reactor Networks ◽  
Gas Recirculation ◽  
The Impact

The increasing amount of renewable energy and emission norms challenge gas turbine power plants to operate at part-load with high efficiency, while reducing NOx and CO emissions. A novel solution to this dilemma is external Flue Gas Recirculation (FGR), in which flue gases are recirculated to the gas turbine inlet, increasing compressor inlet temperature and enabling higher part load efficiencies. FGR also alters the oxidizer composition, potentially leading to reduced NOx levels. This paper presents a kinetic model using chemical reactor networks in a lean premixed combustor to study the impact of FGR on emissions. The flame zone is split in two perfectly stirred reactors modelling the flame front and the recirculation zone. The flame reactor is determined based on a chemical time scale approach, accounting for different reaction kinetics due to FGR oxidizers. The recirculation zone is determined through empirical correlations. It is followed by a plug flow reactor. This method requires less details of the flow field, has been validated with literature data and is generally applicable for modelling premixed flames. Results show that due to less O2 concentration, NOx formation is inhibited down to 10–40% and CO levels are escalated up to 50%, for identical flame temperatures. Increasing combustor pressure leads to a rise in NOx due to thermal effects beyond 1800 K, and a drop in CO levels, due to the reduced chemical dissociation of CO2. Wet FGR reduces NOx by 5–10% and increases CO by 10–20%.

Flue Gas Recirculation in a Gas Turbine: Impact on Performance and Operational Behavior

2011 ◽  
Author(s):  
Frank Sander ◽  
Richard Carroni ◽  
Stefan Rofka ◽  
Eribert Benz
Keyword(s):  
Power Plant ◽  
Co2 Capture ◽  
Flue Gas ◽  
Power Plants ◽  
Combustion Process ◽  
Combined Cycle ◽  
Flue Gas Recirculation ◽  
Overall Performance ◽  
Gas Recirculation ◽  
The Impact

The rigorous reduction of greenhouse gas emissions in the upcoming decades is only achievable with contribution from the following strategies: production efficiency, demand reduction of energy and carbon dioxide (CO2) capture from fossil fueled power plants. Since fossil fueled power plants contribute largely to the overall global greenhouse gas emissions (> 25% [1]), it is worthwhile to capture and store the produced CO2 from those power generation processes. For natural-gas-fired power plants, post-combustion CO2 capture is the most mature technology for low emissions power plants. The capture of CO2 is achieved by chemical absorption of CO2 from the exhaust gas of the power plant. Compared to coal fired power plants, an advantage of applying CO2 capture to a natural-gas-fired combined cycle power plant (CCPP) is that the reference cycle (without CO2 capture) achieves a high net efficiency. This far outweighs the drawback of the lower CO2 concentration in the exhaust. Flue Gas Recirculation (FGR) means that flue gas after the HRSG is partially cooled down and then fed back to the GT intake. In this context FGR is beneficial because the concentration of CO2 can be significantly increased, the volumetric flow to the CO2 capture unit will be reduced, and the overall performance of the CCPP with CO2 capture is increased. In this work the impact of FGR on both the Gas Turbine (GT) and the Combined Cycle Power Plant (CCPP) is investigated and analyzed. In addition, the impact of FGR for a CCPP with and without CO2 capture is investigated. The fraction of flue gas that is recirculated back to the GT, need further to be cooled, before it is mixed with ambient air. Sensitivity studies on flue gas recirculation ratio and temperature are conducted. Both parameters affect the GT with respect to change in composition of working fluid, the relative humidity at the compressor inlet, and the impact on overall performance on both GT and CCPP. The conditions at the inlet of the compressor also determine how the GT and water/steam cycle are impacted separately due to FGR. For the combustion system the air/fuel-ratio (AFR) is an important parameter to show the impact of FGR on the combustion process. The AFR indicates how close the combustion process operates to stoichiometric (or technical) limit for complete combustion. The lower the AFR, the closer operates the combustion process to the stoichiometric limit. Furthermore, the impact on existing operational limitations and the operational behavior in general are investigated and discussed in context of an operation concept for a GT with FGR.

scholarly journals Modeling and Assessment of a Biomass Gasification Integrated System for Multigeneration Purpose

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Shoaib Khanmohammadi ◽  
Kazem Atashkari ◽  
Ramin Kouhikamali
Keyword(s):  
Optimal Design ◽  
Objective Function ◽  
Electrical Power ◽  
Clean Energy ◽  
Biomass Gasification ◽  
Integrated System ◽  
Design Parameters ◽  
Base Case ◽  
Cost Rate ◽  
Gasification Process

The use of biomass due to the reduction in greenhouse gas emissions and environmental impacts has attracted many researchers’ attention in the recent years. Access to an energy conversion system which is able to have the optimum performance for applying valuable low heating value fuels has been considered by many practitioners and scholars. This paper focuses on the accurate modeling of biomass gasification process and the optimal design of a multigeneration system (heating, cooling, electrical power, and hydrogen as energy carrier) to take the advantage of this clean energy. In the process of gasification modeling, a thermodynamic equilibrium model based on Gibbs energy minimization is used. Also, in the present study, a detailed parametric analysis of multigeneration system for undersigning the behavior of objective functions with changing design parameters and obtaining the optimal design parameters of the system is done as well. The results show that with exergy efficiency as an objective function this parameter can increase from 19.6% in base case to 21.89% in the optimized case. Also, for the total cost rate of system as an objective function it can decrease from 154.4 $/h to 145.1 $/h.

Steam Biomass Gasification - Effect of Temperature

2016 ◽  
Vol 832 ◽  
pp. 49-54 ◽  
Author(s):  
Marek Baláš ◽  
Martin Lisý ◽  
Jiří Pospíšil
Keyword(s):  
Negative Impact ◽  
Common Knowledge ◽  
Calorific Value ◽  
Biomass Gasification ◽  
Transformation Process ◽  
Effect Of Temperature ◽  
Producer Gas ◽  
Gaseous Fuels ◽  
Gasification Process ◽  
The Impact

Gasification is one of the technologies for utilization of biomass. Gasification is a transformation process that converts solid fuels into gaseous fuels. The gaseous fuel may be subsequently applied in other technologies with all the benefits that gaseous fuels provide. The principle of biomass gasification is a common knowledge. It is thermochemical decomposition oof the fuel in presence of gasification agent. Heat from the endothermic reaction is obtained by a partial combustion of the fuel (autothermal gasification) or the heat is supplied into a gasifier from the outside (allothermal gasification). Oxygen for the partial combustion is supplied in the gasification medium. Quality, composition and amount of the producer gas depend on many factors which include type of the gasifier, operating temperature and pressure, fuel properties (moisture content) and type and amount of gasification medium. Commonly, air, steam and oxygen and their combinations are used as a gasification medium. Every kind of gasification agents has its significant advantages and disadvantages.Research and analysis of the gasification process must pay special attention to all operating parameters which affect quality and amount of the producer gas that is the efficiency of the conversion itself. Composition of the producer gas, calorific value, and content and composition of impurities are especially observed as these are the basic characteristics directly affecting subsequent application of the gas. Steam addition has a significant impact on gas composition. Steam decomposition into hydrogen and oxygen, and their subsequent reactions increases amount of combustibles, hydrogen, methane and other hydrocarbons. Steam addition in the gasification also affects amount and composition of tar and has a negative impact on heat balance.Energy Institute at the Brno University of Technology has a long tradition in research of biomass gasification in atmospheric fluidized bed reactors. Air was used as a gasification medium. This paper describes our experience with gasification using a mixture of air and steam. We analysed the whole process and in this paper we wish to describe the impact of temperature on outputs of the process, especially temperature of leaving steam and temperature of gasification reactions.

scholarly journals Education and Poverty in Morocco: A Computable General Equilibrium Micro-simulation Analysis

2020 ◽  
Vol 6 (1) ◽  
pp. p116
Author(s):  
Mohamed KARIM ◽  
Mohamed EL MOUSSAOUI
Keyword(s):  
Higher Education ◽  
General Equilibrium ◽  
Computable General Equilibrium ◽  
Simulation Analysis ◽  
Public Investment ◽  
Unit Cost ◽  
Public Spending ◽  
Micro Simulation ◽  
The Government ◽  
The Impact

The paper uses a micro-simulation computable general equilibrium model (CGE) to analyze the impact on poverty of public spending in higher education in Morocco. The model incorporates 7062 households derived from the 2007 National Survey on Household Living Standards (ENNVM). Two scenarios are simulated: a 100% reduction in the unit cost of higher education supported by households and a 50% reduction in public spending on higher education. In this study, it is assumed that the investment behavior of households is linked to the share of the unit cost financed by the government in higher education. The results show that the policy of exempting households from bearing any unit cost of higher education encourages them to invest massively in education, which leads to increasing their income and consequently improving welfare and reducing poverty and inequalities. On the other hand, the reduction in public investment in higher education affects negatively the behavior of households to invest in education which leads to a decrease in welfare, an increase in poverty and a rise of inequalities.

Flue Gas Recirculation in Gas Turbine: Investigation of Combustion Reactivity and NOX Emission

2009 ◽  
Author(s):  
Felix Guethe ◽  
Marta de la Cruz Garci´a ◽  
Andre´ Burdet
Keyword(s):  
Gas Turbine ◽  
Flue Gas ◽  
Gas Turbines ◽  
Nox Emission ◽  
Moderate Increase ◽  
Fuel Injector ◽  
Flue Gas Recirculation ◽  
Combustion Reactivity ◽  
Gas Recirculation ◽  
The Impact

Flue gas recirculation (FGR) is a promising technology for the optimization of post-combustion CO2 capture in natural gas combined cycle (NGCC) plants. In this work, the impact of FGR on lean gas turbine premix combustion is predicted by analytical and numerical investigations as well as comparison to experiments. In particular the impact of vitiated air condition and moderate increase of CO2 concentration into combustion reactivity and NOx emission is studied. The influence of inlet pressure, temperature and recirculated NOx are taken as parameters of this study. Two different kinetic schemes are used to predict the impact that FGR has on the combustion process: the GRI3.0 and the RDO6_NO, which is a newly compiled mechanism from the DLR Stuttgart. The effects of the FGR on the NOx emissions are predicted using a chemical reactor network including unmixedness as presumed probability density function (PDF) to account for real effects. The magnitude and ratio of prompt to post-flame thermal NOx changes with the FGR-ratio producing less post flame NOx at reduced O2 content. For technical mixtures (i. e. an industrial fuel injector), NOx emission can be expected to be lower with the vitiation of the oxidizer. This is due to several effects: at low O2 concentration, the highest possible adiabatic flame temperatures for stoichiometric conditions decreases resulting in lower NOx when averaged over all mixing fractions. Further effects result from lower post flame NOx production and the role of “reburn” chemistry, actually reducing NOx (recirculated from the exhaust), which might become relevant for the high recirculation ratios, where parts of the flame would operate at rich stoichiometry at given unmixedness. Therefore in general for each combustor technical mixing could decrease NOx with respect to perfect mixing at high FGR-ratio assuming the engine can still be operated. Although the findings are quite general for gas turbines the advantage that reheat engines have in terms of operation are highlighted. For reheat engines this can be understood as an extension of the “reheat concept” and used as the next step in the goal to achieve minimal emissions at increasing power. In addition, NOx emission obtained in FGR combustion reduces even further when the engine pressure ratio increases, making the concept particularly well suited for reheat engines.

scholarly journals Experimental and numerical study on combustion of baled biomass in cigar burners and effects of flue gas re-circulation

2016 ◽  
Vol 20 (suppl. 1) ◽  
pp. 151-165 ◽  
Author(s):  
Aleksandar Eric ◽  
Stevan Nemoda ◽  
Dragoljub Dakic ◽  
Branislav Repic ◽  
Dejan Djurovic
Keyword(s):  
Combustion Chamber ◽  
Flue Gas ◽  
Numerical Study ◽  
Combustion Process ◽  
Maximum Temperature ◽  
Biomass Combustion ◽  
Biomass Ash ◽  
Maximum Temperatures ◽  
Gas Recirculation ◽  
The Impact

The paper presents results of experimental and numerical investigation addressing combustion of baled agricultural biomass in a 50 kW experimental furnace equipped with cigar burners. Experiments performed included measurements of all parameters deemed important for mass and energy balance, as well as parameters defining quality of the combustion process. Experimental results were compared with results of numerical simulations performed with previously developed CFD model. The model takes into account complex thermo mechanical combustion processes occurring in a porous layer of biomass bales and the surrounding fluid. The combustion process and the corresponding model were deemed stationary. Comparison of experimental and numerical results obtained through research presented in this paper showed satisfactory correspondence, leading to the conclusion that the model developed could be used for analysis of different effects associated with variations in process parameters and/or structural modifications in industrial biomass facilities. Mathematical model developed was also utilized to examine the impact of flue gas recirculation on maximum temperatures in the combustion chamber. Gas recirculation was found to have positive effect on the reduction of maximum temperature in the combustion chamber, as well as on the reduction of maximum temperature zone in the chamber. The conclusions made provided valuable inputs towards prevention of biomass ash sintering, which occurs at higher temperatures and negatively affects biomass combustion process.

Investigating the impact of donor funding: a case study on Lebanon

2017 ◽  
Vol 12 (1) ◽  
pp. 2-19 ◽  
Author(s):  
Ali Salman Saleh ◽  
Charles Harvie
Keyword(s):  
Design Methodology ◽  
Simulation Analysis ◽  
Potential Outcomes ◽  
Developing Economy ◽  
Donor Funding ◽  
Content Type ◽  
Macroeconomic Impact ◽  
The Government ◽  
The Impact

Purpose The purpose of this paper is to develop a macroeconomic framework to predict the impact of transient donor funding on a developing economy and to facilitate evaluation of the effectiveness of alternative uses of this funding in attaining the desired outcomes. Design/methodology/approach A simulation analysis of the macroeconomic impact of donor funding on the Lebanese economy is conducted. Findings The paper evaluates the potential outcomes for the country from alternative uses of this donor funding and concludes that targeting infrastructure expenditure, mediated through the government, will produce the most beneficial longer term outcomes. Originality/value This paper is the first substantive macro model to be developed for the Lebanese economy. It is the first major study of the contribution of donor funding to the Lebanese macro-economy. The framework, however, can be generalised to other developing donor recipient nations.

Flue Gas Recirculation of the Alstom Sequential Gas Turbine Combustor Tested at High Pressure

2011 ◽  
Author(s):  
Felix Guethe ◽  
Dragan Stankovic ◽  
Franklin Genin ◽  
Khawar Syed ◽  
Dieter Winkler
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Flue Gas ◽  
Operating Conditions ◽  
Limiting Factors ◽  
Combustion System ◽  
Flue Gas Recirculation ◽  
Wide Range ◽  
Gas Recirculation ◽  
The Impact

Concerning the efforts in reducing the impact of fossil fuel combustion on climate change for power production utilizing gas turbine engines Flue Gas Recirculation (FGR) in combination with post combustion carbon capture and storage (CCS) is one promising approach. In this technique part of the flue gas is recirculated and introduced back into the compressor inlet reducing the flue gas flow (to the CCS) and increasing CO2 concentrations. Therefore FGR has a direct impact on the efficiency and size of the CO2 capture plant, with significant impact on the total cost. However, operating a GT under depleted O2 and increased CO2 conditions extends the range of normal combustor experience into a new regime. High pressure combustion tests were performed on a full scale single burner reheat combustor high-pressure test rig. The impact of FGR on NOx and CO emissions is analyzed and discussed in this paper. While NOx emissions are reduced by FGR, CO emissions increase due to decreasing O2 content although the SEV reheat combustor could be operated without problem over a wide range of operating conditions and FGR. A mechanism uncommon for GTs is identified whereby CO emissions increase at very high FGR ratios as stoichiometric conditions are approached. The feasibility to operate Alstom’s reheat engine (GT24/GT26) under FGR conditions up to high FGR ratios is demonstrated. FGR can be seen as continuation of the sequential combustion system which already uses a combustor operating in vitiated air conditions. Particularly promising is the increased flexibility of the sequential combustion system allowing to address the limiting factors for FGR operation (stability and CO emissions) through separated combustion chambers.

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