An Investigation on Low-Temperature Fluidized Combustion of Liquid Fuels

2005 ◽  
Author(s):  
Lorenzo Ferrante ◽  
Michele Miccio ◽  
Roberto Solimene ◽  
Francesco Miccio
Keyword(s):  
Low Temperature ◽  
Pilot Scale ◽  
Operating Conditions ◽  
Liquid Fuels ◽  
Experimental Program ◽  
Data Series ◽  
Low Temperature Combustion ◽  
Splash Zone ◽  
Fuel Injector ◽  
Bed Temperature

Presently, the combustion at low temperature is receiving a great deal of interest because emissions of micro- and nano-pollutants are expected to be greatly reduced. Following previous studies on the low temperature combustion behavior, the authors report results and discussion of steady-state experiments on an atmospheric, pre-pilot scale, 140 mm ID, FB reactor, equipped with an under-bed, air-assisted, liquid-fuel injector. The experimental program was focused on the operation at temperatures lower than the classical value for FBC of solid fuels (i.e., 850°C). The data series taken into consideration are the concentrations of the main unburned species in the splash zone, those of oxygen measured in the bed and in the splash zone as well as the freeboard pressure. The interpretation of the results is mainly based on the statistical analysis in the time domain. The combustion pattern of bio-diesel is compared to that of the diesel fuel under varying operating conditions (e.g., bed temperature, dispersion air velocity at the fuel nozzle, injector height in the bed). Conclusions that were previously published on the base of lab-scale results are checked against new data obtained on the pilot scale. An innovative technique for the analysis of the micro-explosive regime is presented. It consists in the comparison of oxygen concentration measured by the zirconia-based probes at different heights in the bed and in the splash region, pressure signals measured in the freeboard and purposely filtered, and video-recordings of the bed surface phenomena.

FB Combustion of a Biomass Fuel: Comparison Between Pilot Scale Experiments and Model Simulations

2003 ◽  
Author(s):  
Francesco Miccio ◽  
Fabrizio Scala ◽  
Riccardo Chirone
Keyword(s):  
Heat Release ◽  
Pilot Scale ◽  
Combustion Efficiency ◽  
Volatile Matter ◽  
High Reactivity ◽  
Operating Conditions ◽  
Biomass Combustion ◽  
Fluidized Bed Combustion ◽  
Bed Temperature ◽  
Carbon Loading

In the present work the efficiency of the fluidized bed combustion of high-volatile fuels and the extent of volatile matter post-combustion in the splashing zone and freeboard are investigated. A typical Mediterranean biomass (pine-seed shells) has been burned in a pilot-scale bubbling FB combustor (200kWt) at different operating conditions. Both over- and under-bed fuel feeding options have been considered. A FBC model specifically developed for high-volatiles fuels has been also applied to provide a comparison with bed carbon loading, in-bed heat release and splashing region temperature experimental data. Experimental results showed that the biomass combustion efficiency is always very high as a consequence of the high reactivity of the fuel. Extensive volatiles post-combustion above the bed is observed, whose extent appears to be sensitive to the over/under bed feeding option and to the excess air. Approximately 80% of the total heat is released/recirculated in the bed, the remainder leading to appreciable overheating of the freeboard with respect to the nominal bed temperature. Very low bed carbon loadings have been found. Model results compare well with the experimental temperature, heat release and carbon loading trends. However, detailed prediction of the freeboard temperature profiles requires further improvements of the model.

Investigation of Ammonia Formation During Gasification in an Air Blown Spouted Bed

2002 ◽  
Author(s):  
N. Paterson ◽  
Y. Zhuo ◽  
D. R. Dugwell ◽  
R. Kandiyoti
Keyword(s):  
Temperature Control ◽  
Pilot Scale ◽  
Operating Conditions ◽  
Laboratory Scale ◽  
Spouted Bed ◽  
Fuel Gas ◽  
Bed Temperature ◽  
Control Options ◽  
High Concentrations ◽  
Ammonia Formation

High NH3 concentrations were measured in the fuel gas produced by a pilot scale, air blown gasifier that was operated by British Coal. A laboratory scale gasifier has subsequently been developed to investigate the reactions that produce these potentially high concentrations. It has been found that in addition to the NH3 formed through pyrolytic processes, the introduction of steam (or H2 produced by its decomposition) increases the amount formed. The latter reaction produced the higher proportion of the total NH3. The effect of the gasifier operating conditions on the amount of NH3 formed has been studied. The main control options to minimise the NH3 formed are using an alternative method of bed temperature control (i.e. avoid the use of steam), operating with higher bed temperatures and operation at lower pressures.

Prospective fuels for diesel low temperature combustion engine applications: A critical review

2020 ◽  
pp. 146808742096085
Author(s):  
Anand Krishnasamy ◽  
Saurabh K Gupta ◽  
Rolf D Reitz
Keyword(s):  
Low Temperature ◽  
Diesel Fuel ◽  
Alternative Fuels ◽  
Combustion Engine ◽  
Liquid Fuels ◽  
Low Temperature Combustion ◽  
Oxides Of Nitrogen ◽  
Suitable Alternative ◽  
Depth Analysis ◽  
Temperature Combustion

Low Temperature Combustion (LTC) strategies are most promising to simultaneously reduce oxides of nitrogen (NOx) and soot emissions from diesel engines along with offering higher thermal efficiency. Commercial wide spread implementation of diesel LTC strategies requires several challenges to be addressed, including lack of precise ignition timing control, widening the narrow operating load ranges and reducing high unburned fuel emissions. These challenges can be addressed through modifications in the engine or fuel design or both. The timing and rate of combustion in several LTC strategies are controlled primarily by the chemical kinetics of the fuel. Since, diesel fuel reactivity and volatility are tailor-made to perform well under conventional diesel combustion conditions, its application in LTC poses several problems, as highlighted in this paper. Hence, it is important to identify suitable alternative fuels for the different diesel LTC strategies. The published literature on LTC over the past 25 years is critically analyzed to discuss the evolution of the different diesel LTC strategies, their operability limits, the challenges and the controlling parameters for each strategy. This is followed by in-depth analysis of the role of the fuel and the fuel requirements for each strategy. Further, the importance of adopting a hybrid surrogate modeling approach to enable numerical simulation of diesel LTC is highlighted. A novel attempt of relating various diesel low temperature combustion (LTC) strategies based on the approach followed to achieve positive ignition dwell through different injection strategies, utilizing high exhaust gas recirculation (EGR), and dual fuels is presented. The need for replacing diesel with alternative liquid fuels in LTC strategies is presented by highlighting the fundamental problems associated with diesel fuel characteristics. The review concludes by suggesting potential alternative fuels for various diesel LTC strategies and provides directions for future work to address the challenges facing compression ignition LTC operation.

Development of a Catalytic Combustor for a Biomass Fueled Gas Turbine

2000 ◽  
Author(s):  
Etienne Lebas ◽  
Gérard Henri Martin
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Catalytic Combustion ◽  
Pilot Scale ◽  
Operating Conditions ◽  
Liquid Fuels ◽  
Nox Formation ◽  
Economical Analysis ◽  
Reduce Emissions ◽  
Catalytic Combustor

Combustion of biomass derived fuels often results in high emissions levels of pollutants such as NOx, CO and unburned hydrocarbons. In gas turbines, catalytic combustion of biofuels has the potential to reduce emissions of these undesired species. The ULECAT project (Ultra Low Emissions CATalytic combustor), European project led by IFP, initiated the development of an ultra-low emission gas turbine in the range of 1 to 5 MWe, able to run with both biomass derived gases and liquid fuels. The first part of the project has been devoted to the definition of the system and the development of catalysts capable of burning both biomass derived fuels and Diesel fuel. It was mainly focused on high temperature catalyst durability and the reduction of NOx formation. This last point is of primary importance in biofuels combustion and certain catalysts have shown an important potential in reducing ammonia conversion into NOx in some operating conditions. The pilot scale tests have proven the dual fuel operability. Numerical tools were developed and have been validated by pilot tests. They provided useful help in designing the catalytic section of the combustor. An economical analysis of the system have shown the great potential of catalytic combustion in reducing the operating costs and investment compared to SCR or ammonia scrubbing.

Development of a Dual Fuel Catalytic Combustor for a 2.3 MWe Gas Turbine

1998 ◽  
Author(s):  
Jean-Hervé Le Gal ◽  
Gérard Martin ◽  
Daniel Durand
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Life Time ◽  
Pilot Scale ◽  
Operating Conditions ◽  
Liquid Fuels ◽  
Dual Fuel ◽  
Nox Formation ◽  
Waste Products ◽  
Catalytic Combustor

Biomass derived fuels are an essential alternative for heat and energy production, in order to minimise environmental impact, since they make no net contribution to the increase of CO2 emissions into the atmosphere. In certain countries, biofuels are also interesting since they are available as waste products from the agricultural or forestry industry. Unfortunately, combustion of biofuels often results in high emissions levels of pollutants such as NOx, CO and unburned hydrocarbons. In gas turbines, catalytic combustion of biofuels has the potential to reduce emissions of these undesired species. The ULECAT project (Ultra Low Emissions CATalytic combustor) described in this paper is the first step of a program aiming at the development of an ultra-low emission gas turbine in the range of 1 to 5 MWe, able to run with both biomass-derived gases and liquid fuels. The objective of the project is to assess the feasibility of a dual fuel catalytic combustor. Combustor design issues are investigated at full and part load conditions. For the comparison of combustor configuration, modelling provides a useful help for catalytic section design, in particular for the estimation of catalytic activity and wall temperature which strongly influence catalyst life time. Catalyst development is one of the main topics of this project. It is mainly focused on high temperature catalyst durability and the reduction of NOx formation. This last point is of primary importance in biofuels combustion and certain catalysts have shown an important potential in reducing ammonia conversion into NOx in some operating conditions. Catalyst performances are evaluated at lab scale and also pilot scale in representative gas turbine combustor conditions with both Diesel fuel and biomass derived fuels.

Numerical Studies of Combustion Recession on ECN Diesel Spray A

2018 ◽  
Author(s):  
Xiaohang Fang ◽  
Riyaz Ismail ◽  
Martin H. Davy ◽  
Joseph Camm
Keyword(s):  
Low Temperature ◽  
Primary Objective ◽  
Operating Conditions ◽  
Hole Injection ◽  
Navier Stokes ◽  
Combustion Model ◽  
Low Temperature Combustion ◽  
Flamelet Model ◽  
Auto Ignition ◽  
Flamelet Generated Manifold

It is known that low-temperature combustion (LTC) strategies can help simultaneously reduce nitrogen oxides (NOx) and particulate matter (PM) emissions from diesel engines to very low levels. However, it is also known that LTC may cause emissions of unburned hydrocarbons (UHC) to rise — especially in low load operating conditions. Recent studies indicate that end-of-injection (EOI) processes may support ignition recession back to injector nozzle thereby helping to reduce these emissions. This paper contributes to the physical understanding of this EOIphe-nomenon, combustion recession, using computational fluid dynamics studies at LTC conditions. Simulations are performed on a single-hole injection of n-dodecane under a range of Engine Combustion Network’s “Spray A” conditions. The primary objective of this paper is to assess the ability of a Flamelet Generated Manifold (FGM) combustion model to predict and characterize combustion recession. First, a baseline condition FGM simulation is compared with two other combustion models namely the Well Stirred model (WSR), the Representative Interactive Flamelet model (RIF) using the commercially-available CFD solver, CONVERGE. Further studies were carried out for FGM model alone including: varying ambient temperature conditions and chemical mechanisms. Two chemical kinetics mechanisms with low temperature chemistry for n-dodecane are employed to help to predict the occurrence of combustion recession. All simulations are performed under the Reynolds-Averaged Navier-Stokes (RANS) framework in a grid-converged Lagrangian spray scenario. The simulation of combustion recession is qualitatively validated against experimental data from literature and the efficacy of each model in predicting combustion recession is evaluated. Overall, it was found that the FGM model was able to capture the combustion recession phenomenon well — showing particular strength in predicting distinct auto-ignition events in the near nozzle region.

Fluidized Bed Combustion of a Biomass Fuel: Comparison Between Pilot Scale Experiments and Model Simulations

2005 ◽  
Vol 127 (2) ◽  
pp. 117-122 ◽  
Author(s):  
Francesco Miccio ◽  
Fabrizio Scala ◽  
Riccardo Chirone
Keyword(s):  
Heat Release ◽  
Fluidized Bed ◽  
Pilot Scale ◽  
Volatile Matter ◽  
High Reactivity ◽  
Operating Conditions ◽  
Biomass Combustion ◽  
Fluidized Bed Combustion ◽  
Bed Temperature ◽  
Carbon Loading

In the present work the efficiency of the fluidized bed combustion (FBC) of high-volatile fuels and the extent of volatile matter post-combustion in the splashing zone and freeboard are investigated. A typical Mediterranean biomass (pine-seed shells) has been burned in a pilot-scale bubbling FB combustor (200 kWt) at different operating conditions. Both over-and under-bed fuel feeding options have been considered. A FBC model specifically developed for high-volatile fuels has been also applied to provide a comparison with bed carbon loading, in-bed heat release and splashing region temperature experimental data. Experimental results showed that the biomass combustion efficiency is always very high as a consequence of the high reactivity of the fuel. Extensive volatile post-combustion above the bed is observed, whose extent appears to be sensitive to the over/under bed feeding option and to the excess air. Approximately 80% of the total heat is released/recirculated in the bed, the remainder leading to appreciable overheating of the freeboard with respect to the nominal bed temperature. Very low bed carbon loadings have been found. Model results compare well with the experimental temperature, heat release and carbon loading trends. However, a detailed prediction of the freeboard temperature profiles requires further improvements of the model.

Application of a Pilot-Scale Pulsed Electrocoagulation system to OCC-Based Paper Mill Effluent

TAPPI Journal ◽  
2009 ◽  
Vol 8 (3) ◽  
pp. 14-20 ◽  
Author(s):  
YUAN-SHING PERNG ◽  
EUGENE I-CHEN WANG ◽  
SHIH-TSUNG YU ◽  
AN-YI CHANG
Keyword(s):  
Water Quality ◽  
Quality Indicators ◽  
Paper Mill ◽  
Pilot Scale ◽  
Operating Conditions ◽  
Optimal Dosage ◽  
Water Quality Indicators ◽  
Paper Mill Effluent ◽  
Treated Effluent ◽  
True Color

Trends toward closure of white water recirculation loops in papermaking often lead to a need for system modifications. We conducted a pilot-scale study using pulsed electrocoagulation technology to treat the effluent of an old corrugated containerboard (OCC)-based paper mill in order to evaluate its treatment performance. The operating variables were a current density of 0–240 A/m2, a hydraulic retention time (HRT) of 8–16 min, and a coagulant (anionic polyacrylamide) dosage of 0–22 mg/L. Water quality indicators investigated were electrical con-ductivity, suspended solids (SS), chemical oxygen demand (COD), and true color. The results were encouraging. Under the operating conditions without coagulant addition, the highest removals for conductivity, SS, COD, and true color were 39.8%, 85.7%, 70.5%, and 97.1%, respectively (with an HRT of 16 min). The use of a coagulant enhanced the removal of both conductivity and COD. With an optimal dosage of 20 mg/L and a shortened HRT of 10 min, the highest removal achieved for the four water quality indicators were 37.7%, 88.7%, 74.2%, and 91.7%, respectively. The water qualities thus attained should be adequate to allow reuse of a substantial portion of the treated effluent as process water makeup in papermaking.

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