Gaseous Combustion Products Research Articles

Influence of reaction mechanism accuracy on the chemical reactivity prediction of complex charring material in fire condition

The production of combustible gases from solids during thermal decomposition and how these gases feed the flame take an important part in the currently fire research. In this context, the modelling of the thermal, chemical and physical phenomena in the condensed phase constitutes a key step to accurately predict the gases production (source term). This modelling applies to establish a relationship between the kinetics of gases production (thermal decomposition of the matter), the solid temperature and the atmosphere composition (% of oxygen). Due to digital progress, the accuracy of modelistic approaches does not depend on the resolution technique, but rather on the accurate description of the apparent chemical reaction pathway. This mechanism, identified through the matter scale experiment, will define the number of kinetic parameters to be estimated. This study focuses on the complexity level of the reaction mechanism, and its effect on the accuracy of the chemical reactivity forecast. The analysis is thereby performed on a solid material (polyisocyanurate foam) with a complex multi-step mechanism. Several mechanisms complexity with various levels of sophistication (number of linked reactions) are studied while their results are presents and discussed. This work uses a new statistical technic based on statistical criteria to judge the quality of the model and to choose a reaction mechanism with a degree of complexity adapted to fire modelling at large scale. The analysis done reveals a possibility to simplify the initial reaction mechanism⿿s complexity, without influencing the accuracy of forecasts. These works have therefore demonstrated that the use of highly simplified mechanisms enables the reproduction of the complex decomposition kinetics of the PIR foam. On the other hand, the use of a detailed reaction pathway is not always necessary to predict the decomposition of complex material through modelistic methods.

The study of formation and acid precipitation dynamics as a result of big natural and man-made fires

In the event of big natural and man-made fires, many hazardous chemicals are released into the environment. These compounds react with the atmospheric components to form sulfuric and nitric acids. Among the atmospheric components, highly active radicals - hydroxyl, hydroperoxide and nitrate ions have the greatest influence on the acid formation processes. The reaction of acids with atmospheric water leads to acid precipitation. The paper discusses the physical and chemical features of the transformation of gaseous combustion products into acidic products. Using the kinetic multilayer model of gas particles, the absorption dynamics of gas-phase nitric and sulfuric acids by water microdroplets in the atmosphere is considered. Further evolution of acid solution microdroplets occurs due to coagulation. The coagulation rate significantly depends on the relative sizes of droplets. The criterion is the Knudsen number, which determines the flow of Brownian or gravity coagulation. The motion of small droplets is determined by the interaction with heat molecules and the absence of sedimentation. As for relatively large droplets, interaction with heat molecules can be neglected. They settle in the air stream due to weight and absorb small droplets when colliding. The intensity of the coagulation growth of droplets in the course of precipitation is determined using the mathematical simulation.

A new flame retardant on the basis of diethylenetriamine copper(II) sulfate complex for combustibility suppressing of epoxy-amine composites

The crystals of diethylenetriamine copper(II) sulfate complex (flame retardant) denoted as DETA-CuSO4 have been obtained by direct interaction of solid copper(II) sulfate pentahydrate with diethylenetriamine – DETA (hardener of epoxy resins) and characterized by means of X-ray powder diffraction, infrared spectra (IR) and thermal gravimetric analysis (TGA). The results of TGA reveal that the thermal degradation of DETA-CuSO4 takes place at 290°С, while the maximal temperature of combustion gaseous products amounts to 520°С. DETA-CuSO4 has been used as flame retardant in epoxy-amine polymers (DGEBA/DETA). The thermal behavior and combustibility of modified epoxy-amine composites (DGEBA/DETA-CuSO4) have been investigated using TGA, method of “ceramic tube” (CT) as well as measurement of ignition point and self-ignition point. TGA data confirms that adding DETA-CuSO4 to DGEBA (bisphenol A diglycidyl ether) appreciably improve the thermic stability and anti-flammability of DGEBA/DETA-CuSO4, mainly, owing to chemically interlinking incombustible inorganic salt of copper(II) sulfate with polymeric framework of DGEBA/DETA. Results of CT measurement show that the maximal combustion temperature of gaseous products for DGEBA/DETA in comparison with DGEBA/DETA-CuSO4 goes down from 867°C to 640°C and weight loss decreases from 89.0wt% to 78.6wt%.

Formation of Liquid Products at the Filtration Combustion of Solid Fuels

Yields of liquid and gaseous products of the filtration combustion of cellulose, wood, peat, coal, and rubber have been investigated. Experiments have shown that the gasification of solid fuels in the regime with superadiabatic heating yields liquid hydrocarbons with quantity and quality, which are close to those produced using other methods, for example, by pyrolysis. But in this case no additional energy supply is needed to carry out the gasification process. The low calorific combustible gas, which forms in this process, contains a substantial quantity of carbon monoxide and hydrogen, which are components of syngas.

Intensive evaporation and boiling of a heterogeneous liquid droplet with an explosive disintegration in high-temperature gas area

The using of the high-speed (not less than 105 frames per second) video recording tools (“Phantom”) and the software package (TEMA Automotive) allowed carrying out an experimental research of laws of intensive vaporization with an explosive disintegration of heterogeneous (with a single solid nontransparent inclusion) liquid droplet (by the example of water) in high-temperature (500-800 K) gases (combustion products). Times of the processes under consideration and stages (liquid heat-up, evaporation from an external surface, bubble boiling at internal interfaces, growth of bubble sizes, explosive droplet breakup) were established. Necessary conditions of an explosive vaporization of a heterogeneous droplet were found out. Mechanisms of this process and an influence of properties of liquid and inclusion material on them were determined.

Mechanism of primary fragmentation of coal in fluidized bed

In order to lay a foundation of a credible primary fragmentation model, a theoretical analysis of the thermo-mechanical processes in a devolatilizing solid fuel particle was carried out. The devolatilization model comprises heat transfer, chemical processes of generation of gaseous products of combustion (volatiles), volatile transfer, and solid mechanic processes. A spatial and temporal analysis of the stresses within the particle showed that the radial stress is caused primarily by the pressure of generated volatiles. This stress monotonously decreases from the particle center towards the particle surface, without changing its sign. The tangential stress is caused primarily by the thermal shock. Close to the surface, it changes its sign. In the particle cross-section, the radial stress prevails close to the particle center, whilst the tangential stress is dominant in the surface region. At the points where these stresses exceed the particle tensile strength, cracks occur. Cracks extend tangentially close to the surface, and radially close to the center of the particle.

Synthesis of a novel cross‐linked organophosphorus‐nitrogen containing polymer and its application in flame retardant epoxy resins

SummaryA novel cross‐linked organophosphorus–nitrogen polymetric flame retardant additive poly(urea tetramethylene phosphonium sulfate) defined as PUTMPS was synthesized by the condensation polymerization between urea and tetrahydroxymethyl phosphonium sulfate. Its chemical structure was well characterized by Fourier transform infrared (FTIR) spectroscopy, 13C and 31P solid‐state nuclear magnetic resonance. The synthesized PUTMPS and curing agent m‐phenylenediamine were blended into epoxy resins to prepare flame retardant epoxy resin thermosets. The effects of PUTMPS on fire retardancy and thermal degradation behavior of EP/PUTMPS thermosets were investigated by limiting oxygen index (LOI), vertical burning test (UL‐94), cone calorimeter measurement, and thermalgravimetric analysis (TGA) tests. The surface morphologies and chemical compositions of char residues for cured epoxy resins were investigated by scanning electron microscopy and X‐ray photoelectron spectroscopy (XPS), respectively. Water resistant properties of epoxy resin thermosets were evaluated by putting the samples into distilled water at 70°C for 168 h. The results demonstrated that the EP/12 wt% PUTMPS thermosets successfully passed UL‐94 V‐0 flammability rating and the LOI value reached 31.3%. The TGA results indicated that the incorporation of PUTMPS promoted epoxy resin matrix decomposed and char forming ahead of time, which led to a higher char yield and thermal stability for epoxy resin thermosets at high temperature. The morphological structures and analysis of XPS for the char residues of the epoxy resin thermosets shown that PUTMPS benefited to the formation of a sufficient, more compact, and homogeneous char layer with rich flame retardant elements on the materials surface during burning, which prevented the heat transmission and diffusion, limited the production of combustible gases, inhibited the emission of smoke, and then led to the reduction of the heat release rate and smoke produce rate. After water resistance tests, EP/12 wt% PUTMPS thermosets still remained excellent flame retardancy. Copyright © 2015 John Wiley & Sons, Ltd.

Comparing pelletization and torrefaction depots: Optimization of depot capacity and biomass moisture to determine the minimum production cost

In the present study, the biomass upgrading depot capacity and biomass feedstock moisture were optimized to obtain the minimum production cost at the depot gate for the production of woody biofuels. Three technology scenarios are considered in this study: (1) conventional pellets (CP), (2) modestly torrefied pellets (TP1) and (3) severely torrefied pellets (TP2). TP1 has the lowest cost of $7.03/GJLHV at a moisture of 33wt.% and a depot size of 84MWLHV. The effects of climatic conditions and biomass field conditions were also studied for three scenarios. In humid regions of Michigan, TP2 is more economical than other scenarios because of the increased production of combustible gas. The three scenarios have similar sensitivities to biomass field conditions.

New optical exchange gap concept to calculate self-irradiance direct exchange areas in cylindrical industrial furnaces

A direct integration scheme based on the trapezoidal integration method associated with Romberg's acceleration algorithm is proposed to calculate numerically with the desired accuracy, direct exchange areas (DEAs) within an axisymmetric enclosure confining non-isothermal and inhomogeneous non-grey gaseous combustion products with soot. A three-dimensional integral needs to be evaluated, but axisymmetry and reciprocity of DEAs bring a notable processing time reduction. The integration process poses difficulties pertinent to singular DEAs of self-irradiance. Evaluating self-irradiance of gas volume zones is the concern of this investigation, in which we introduce a new concept that we call the optical exchange gap (OEG). It has been established that the OEG width associated with a volume zone, optimized with extreme care to meet Erkku's data, decreases with the radial position and radial optical thickness. A correlation, deduced to derive the OEG width for a given situation, has been shown to be more efficient, simple and accurate than a proper center-to-center distance technique. The effectiveness of the developed procedure was demonstrated by comparison of model predictions, using the zonal method in conjunction with the weighted-sum of grey gases (WSGG) model, with highly accurate reference data and by carrying out an error analysis.

Parametric study and process optimization for solar pyrolysis of beech wood

Solar pyrolysis process offers solution to utilize solar energy for converting biomass energy into solar fuel. A Box–Behnken design of experiments was performed to optimize a solar pyrolysis process for the production of combustible gases from beech wood. Response surface methodology (RSM) was used to study the effects of temperature, heating rate and argon flow rate on products distribution, gas LHV (lower heating value) and gas composition. The operating variables were as follows: temperature (800–2000°C), heating rate (50–450°C/s) and argon flow rate (4–8NL/min). A second-order regression model was used to predict the responses. The proposed model described well the experimental values. The analysis of variance (ANOVA) was performed with Minitab 17 software and the significant effect of the factors and their interaction effects were tested at 95% confidence interval. The gas LHV was significantly influenced by temperature and heating rate. The maximum gas LHV higher than that of initial beech wood was found as 14,589kJ/kg under process conditions as: 2000°C temperature, 450°C/s heating rate. The beech wood calorific value is upgraded through solar pyrolysis.

Formation and Control of Sulfur Oxides in Sour Gas Oxy-Combustion: Prediction Using a Reactor Network Model

Sour natural gas currently requires expensive gas cleanup before it can be used in power generation because it contains large amounts of hydrogen sulfide (H2S) and carbon dioxide (CO2) that entail a low heating value and highly corrosive combustion products. A potential alternative is to use the gas directly in a gas turbine process employing oxy-fuel combustion, which could eliminate the need for gas cleanup while also enabling the application of carbon capture and sequestration, possibly combined with enhanced oil recovery (EOR). However, the exact influence of an oxy-fuel environment on the combustion products of sour gas has not been quantified yet. In this work, we used a reactor network model for the combustor and the gas turbine together with our recently assembled and validated detailed chemical reaction mechanism for sour gas combustion to investigate the influence of some basic design parameters on the combustion products of natural gas and sour gas in CO2 or H2O diluted oxy-fuel combustion as w...

Synthesis of a novel phosphonate flame retardant and its application in epoxy resins

ABSTRACTA novel phosphonate flame retardant additive bis(2,6‐dimethyphenyl) phenylphosphonate (BDMPP) was synthesized from phenylphosphonic dichloride and 2,6‐dimethyl phenol, and its chemical structure was characterized by Fourier transform infrared (FTIR) spectroscopy, 1H and 31P nuclear magnetic resonance. The prepared BDMPP and curing agent m‐phenylenediamine were blended into epoxy resins (EP) to prepare flame retardant EP thermosets. The effect of BDMPP on fire retardancy and thermal degradation behavior of EP/BDMPP thermosets was investigated by limiting oxygen index (LOI), vertical burning test (UL‐94), cone calorimeter and thermalgravimetric analysis (TGA). The morphologies of char residues of the EP thermosets were investigated by scanning electron microscopy (SEM) and the water resistant properties of thermosets were evaluated by putting the samples into distilled water at 70°C for 168 h. The results demonstrated that the cured EP/14 wt % BDMPP composites with the phosphorus content of 1.11 wt % successfully passed UL‐94 V‐0 flammability rating and the LOI value was as high as 33.8%. The TGA results indicated that the introduction of BDMPP promoted EP matrix decomposed ahead of time compared with that of pure EP and led to a higher char yield at high temperature. The incorporation of BDMPP enhanced the mechanical properties and reduced the moisture absorption of EP thermosets. The morphological structures of char residue revealed that BDMPP benefited to the formation of a more compact and homogeneous char layer on the materials surface during burning, which prevented the heat transmission and diffusion, limit the production of combustible gases and then lead to the reduction of the heat release rate. After water resistance tests, EP/BDMPP thermosets still remained excellent flame retardancy. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42765.

Experimental study on the impact of reactant gas pressure in the conversion of coal char to combustible gas products in the context of Underground Coal Gasification

This paper describes an experimental investigation to determine the impact of pressurised reactor conditions within the reduction zone of a gasification process employing a semi-batch reactor with a bituminous coal. The conditions examined with this bespoke pressurised rig were designed to be representative of an Underground Coal Gasification (UCG) process, at pressures up to 3.0MPa and temperatures up to 900°C; coal samples were approximately 36g per test. Current published literature suggests that one of the key controlling factors in the conversion and yield within such processes is the behaviour of the pyrolysed coal (char) in the reduction zone of the UCG cavity. This was achieved by using carbon dioxide and steam as the primary reductants with char derived from bituminous coal at a variety of pressure and temperature levels, plus at a range of relative H2O/CO2 proportions. The composition of the resulting product gas was measured and subsequently used to calculate cold gas efficiency and carbon conversion (during 90min at steady state). A shrinking core model was then employed to determine the activation energy and pre-exponential factor under these conditions. The results were then used to extrapolate the contribution of the reduction zone in published research including UCG field trials where discrete analysis of the zones within the gasification cavity was not possible. It was shown that pressure increases the reduction–gasification process of the char in terms of carbon conversion, cold gas efficiency and heating value of the product gas. Under the conditions evaluated herein, optimum gasification conditions for the bituminous coal were determined as 1.65MPa at H2O/CO2 ratio of 2:1 by mass at 900°C which produced a syngas with a composition of 17.4% CO, 3% CH4, 42.1% H2 and LHV of 7.8MJ/Nm3.

Investigation of Polycyclic Aromatic Hydrocarbons (PAHs) and Methoxyphenols (MPs) from laboratory scale thermal oxidation of waste wood samples

In the present study, Polycyclic Aromatic Hydrocarbons (PAHs) and Methoxyphenols (MPs) emitted from the low temperature oxidation of the waste wood samples were identified in the laboratory scale small burning system. Four types of waste wood including untreated hardwood (HW), untreated softwood (SW), treated roof material (RM) and treated window frame (WF) were examined during the experiments. XAD-2 adsorbent tubes were used for sampling of the gaseous combustion products. After extraction of the sample tubes, extracts were analyzed by using the Hewlett Packard 6890 GC coupled with Agilent 5971 Mass Selective (MS) Detector. The relative average contributions of the naphthalene, acenaphthylene and retene in hardwood samples were found higher than those measured in softwood. On the contrary, the relative average contribution of the phenanthrene, anthracene, fluoranthene, benzo(a)anthracene, chrysene and benzo(b)fluoranthene to the total PAH concentration in softwood samples were obtained higher as compared to hardwood sample. Syringol, 4-methyl syringol, 4 methyl guaiacol, eugenol, properlysyringol, 4-ethylsyringol, syringylacetone and iso-eugenol were found to be most abundant compounds in the hardwood samples. On the other hand, the most observed compounds in the softwood samples were 4-methylguacicol, iso-eugenol, guaiacol, eugenol and vanillin.

Synthesis of a cross-linked triazine phosphine polymer and its effect on fire retardancy, thermal degradation and moisture resistance of epoxy resins

A novel cross-linked triazine phosphine polymeric flame retardant additive polymelamine tetramethylene phosphonium sulfate defined as PMTMPS was synthesized by the condensation polymerization between melamine and tetrahydroxymethyl phosphonium sulfate. Its chemical structure was well characterized by Fourier transform infrared (FTIR) spectroscopy, 13C and 31P solid-state nuclear magnetic resonance. The synthesized PMTMPS and curing agent m-phenylenediamine were blended into epoxy resins to prepare flame retardant epoxy resins thermosets. The effects of PMTMPS on fire retardancy and thermal degradation behavior of the cured EP/PMTMPS composites were investigated by limiting oxygen index (LOI), vertical burning test (UL-94), cone calorimeter measurement (cone) and thermogravimetric analysis (TGA) tests. The morphologies and chemical compositions of char residues for cured epoxy resins were investigated by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. Moisture resistant properties of epoxy resins thermosets were evaluated by putting the samples into distilled water at 70 °C for 168 h. The results demonstrated that the cured EP/11 wt % PMTMPS composites successfully passed UL-94 V-0 flammability rating and the LOI value was as high as 32.5%. The TGA results indicated that the incorporation of PMTMPS stimulated epoxy resins matrix decomposed and char forming ahead of time, which led to a higher char yield and thermal stability for epoxy resins thermosets at high temperature. The morphological structures and the analysis results of XPS for char residues of thermosets revealed that the introduction of PMTMPS benefited to the formation of a sufficient, more compact and homogeneous char layer with rich flame retardant elements on the materials surface during burning, which prevented the heat transmission and diffusion, limited the production of combustible gases, inhibited the emission of smoke and then led to the reduction of the heat release rate and smoke produce rate. The results of water resistance tests shown the moisture absorption of EP/PMTMPS thermosets was lower than that of pure epoxy resins thermosets and the samples still remained excellent flame retardancy after water resistance tests.

Electro-Static Discharge Ignition of Monolayers of Nanocomposite Thermite Powders Prepared by Arrested Reactive Milling

Reactive nanocomposite powders with aluminum as a fuel and copper, bismuth, iron, and molybdenum oxide as oxidizers: 2Al·3CuO, 2.35Al·Bi2O3, 2Al·Fe2O3, and 2Al·MoO3, were prepared by arrested reactive milling, placed in monolayers on a conductive substrate, and ignited by an electro-static discharge (ESD) or spark in air, argon, and vacuum. The ESD was produced by discharging a 2000 pF capacitor charged to a voltage, which varied from 5 to 20 kV. Emission from ignited particles was monitored using a photomultiplier equipped with an interference filter. Experimental variables included particle sizes, milling time used to prepare composite particles, surrounding environment, and starting ESD voltage. All materials ignited in all environments, producing individual burning particles that were ejected from the substrate. The spark duration varied from 1 to 5 μs; the duration of the produced emission pulse was in the range of 80–250 μs for all materials studied. The longest emission duration was observed for the nanocomposite thermite using MoO3 as an oxidizer. The reaction rates of the ESD-initiated powders were defined primarily by the scale of mixing of and reactive interface area between the fuel and oxidizer in composite materials rather than by the external particle surface or particle dimensions. In vacuum, particles were heated by ESD while remaining on the substrate until they began generating gas combustion products. In air and argon, particles initially pre-heated by ESD were lifted and accelerated to ca. 100 m/s by the generated shock wave; the airborne particles continued self-heating due to heterogeneous redox reactions.

Modeling interactions between chemistry and turbulence for simulations of partial oxidation processes

Methane Autothermal Reforming (ATR) and non-catalytic partial oxidation (POX) are two industrial processes used to produce syngas, a mixture of hydrogen and carbon monoxide. In those reactors, methane is burnt with oxygen in fuel-rich conditions. Downstream of the flame, the gaseous combustion products further react with steam and remaining methane in the turbulent "post-flame" region. In order to perform Reynolds Average Navier–Stokes (RANS) simulations of the reactor, accurate modeling strategies are required to compute the average chemical source terms in this post-flame region. In the present study, a DNS numerical experiment has been performed to reproduce the properties of the flow in this part of the reactor. Results are used as a reference to a priori assess the performances of different modeling strategies derived from three turbulent combustion models. The results of this analysis show that, among the three selected models, only the two models based on tabulated chemistry description are able to properly recover the right values of the average chemical source term. The PCM-FPI approach, based on a one-point statistic description using a Beta density probability function, appears as the most accurate approach compared to the two others.

Real-Time Monitoring and Assessment of Thermal and Toxicological Risk Associated with Fire Retardant Textiles in a Full-Size Simulation of an Engulfment Flash Fire

A comparative risk assessment was performed on nine commercial flame-retardant materials in garments intended for general occupational use. The assessment evaluated the relative hazards associated with combustion gases during a full engulfment flash fire in accordance with ASTM F1930 and ISO 13506. The materials in the form of whole body coveralls were subjected to propane-fired flash conditions of 84 kW/m2 for a duration of 3 or 4 s. Combustion gas composition and concentrations were measured in the breathing zone of the test manikin in real time by Fourier transform infrared spectrophotometry as was the gas temperature. Results were used to parameterize thermokinetic and toxicokinetic models used to predict both injury and gas exposure. The results indicated that an individual maintaining regular ventilation would receive third degree burns to the upper airway at both durations. In the case of the 4 s burn, third degree injury would reach the larynx, resulting in involuntary apnea, in about 12 s post-ignition. Combustion gas production was high, but of very short duration meaning that exposure was limited by the receptor’s ventilation cycle. Hazards to parties giving aid were limited by rapid declines in combustion gas production and temperature that returned to background concentrations within about 60 s post-ignition. Comparisons made between materials indicated the marked presence of hydrogen chloride, cyanide, and nitrogen dioxide production for the fire retardant (FR) modacrylic blends; cyanide, nitrogen dioxide, and sulfur dioxide for FR cotton; and sulfur dioxide for the FR rayon blends. None of the gas exposures were found to represent a significant risk to health or impedance to survival or escape to the individual wearing the garment, or other persons that may come to their assistance. Particulate antimony was detected in the technologies that use it as a fire retardant, but at concentrations well below anything that could be considered hazardous.

Synergistic flame-retardant effects between aluminum hypophosphite and expandable graphite in silicone rubber composites

The main aim of this work was to investigate the synergistic effect of expandable graphite (EG) and aluminum hypophosphite (AHP) on the flame retardancy of silicone rubbers (SR). The synergistic effects of EG with AHP in halogen-free flame-retardant SR composites have been studied by cone calorimeter test (CCT), thermogravimetric analysis (TG), and the thermogravimetric analysis/infrared spectrometry (TG–IR). The CCT results showed that AHP and EG can effectively reduce the flammable properties including peak heat release rate, total heat release, smoke production rate, total smoke release, and smoke factor. An improvement of thermal stability of SR/AHP/EG was also observed. The experimental observations from digital photographs give positive evidence of the synergistic effects between AHP with EG. The TG results reveal that SR/AHP/EG samples show slower thermal degradation rate and higher thermal stability at high temperature than SR sample. The TG–IR results showed that the addition of AHP and EG significantly decreased the combustible gaseous products such as hydrocarbons. These attractive features of SR/AHP/EG suggest that the method proposed herein is a good approach to prepare very effective flame retardants and corresponding super flame-retarding SR.

Nonpremixed and Premixed Combustion of Mixtures of Producer Gas and Methane

Abstract Experimental and kinetic modeling studies are carried out to characterize nonpremixed and premixed combustion of producer gas and mixtures of producer gas and methane. The producer gas, employed in the study, is made up of 55.00% carbon monoxide, 2.34% hydrogen, 12.72% methane, 5.24% ethene, and 24.7% carbon dioxide by mass. The primary focus is on characterizing the chemical influence of addition of producer gas on combustion of methane. The kinetic modeling studies are carried out employing a detailed chemical-kinetic mechanism, called the San Diego Mechanism, a skeletal mechanism, and a reduced mechanism made up of five global steps. Experiments on nonpremixed combustion are carried out employing the counterflow configuration. Critical conditions of extinction are measured for producer gas, methane, and mixtures of producer gas and methane. They are compared with predictions obtained using the detailed, skeletal, and reduced mechanism. Critical conditions of autoignition are measured for producer gas and compared with the predictions obtained employing the detailed mechanism. Experimental data and predictions show that with increasing amounts of producer gas in the mixture, the flame is more difficult to extinguish. Flame structures show that at a fixed value of the strain rate, leakage of oxygen from the reaction zone decreases with increasing amounts of producer gas in the combustible mixture. This is attributed to enhanced consumption of oxygen in an overall chain branching step that consumes hydrogen. Thus, the increase in the overall reactivity of the combustible mixture is attributed to presence of hydrogen in producer gas. Computations are performed, using the detailed mechanism and the skeletal mechanism, to investigate aspects of premixed combustion of stoichiometric mixtures of producer gas, methane, oxygen, and nitrogen at fixed values of adiabatic temperature. Burning velocities are calculated. They are found to be less sensitive to the amount of producer gas in the mixture. This is qualitatively different from that observed for nonpremixed combustion. It is attributed to complete consumption of all reactants including oxygen and combined influences of H2 and CO in producer gas on overall combustion of methane. A third set of computations was performed on strained premixed flames stabilized in counterflow between a stream of a stoichiometric mixture of producer gas, methane, oxygen, and nitrogen, and a stream of nitrogen at fixed adiabatic temperature. Critical conditions of extinction were obtained. The strain rate at extinction increased with increasing amounts of producer gas. The increase was comparable to that observed for nonpremixed combustion of these fuels.