Combustion Gas Composition Research Articles

Comparison of Combustion Gas Emission by Low Power Boilers Fired by Biomass Obtained from Wood - Pellets

This paper discusses the relationship between the furnace structure in low power boilers fired by biomass and the composition of combustion gas emitted to the atmosphere. The emissivity of the boilers was also assessed by determination of a generalised criterial parameter of a boiler evaluation and a ranking of boiler emissivity was drawn up. A significant correlation was found to exist between the content of nitrogen oxides and carbon monoxide in the combustion gas. The carbon dioxide content was also found to affect CO and NOx content in the emitted combustion gas.

Development of databases and generation of stability diagrams pertaining to the modelling of processes during hot corrosion of heat exchanger components

The purpose of the project “Optimisation of In-Service Performance of Boiler Steels by Modelling High Temperature Corrosion” (G5RD-CT-2001-00593, acronym OptiCorr) was to establish a set of focused procedures, both in terms of applications of thermochemical standard software and in terms of dedicated new developments, which enable a user to investigate the behaviour of boiler components based on the application of rigorous thermodynamics. Thermodynamic databases which cover the materials involved had to be compiled and assessed in order to be able to apply the appropriate software. Particular new results coming from the databases work will be highlighted. The results of phase equilibrium calculations are shown in appropriate diagrams and compared with published experimental data. The thermochemical standard software FactSage permits the investigation of stoichiometric reactions, complex equilibria and phase diagrams. These calculational capabilities have been applied for the purposes of investigation of (1) the composition of complex combustion gases, (2) metal-gas interactions and (3) metal-gas-molten salt interactions, since these have been established to be the key points for the understanding of the corrosion of heat exchanger components. Selected results from these calculations will be demonstrated and discussed. Application specific software has been developed using the approach of local chemical equilibrium calculated by the programmer's library ChemApp and the add-in ChemSheet for Microsoft EXCEL™. Two key processes have been treated: The internal corrosion of the metallic material by diffusion of gases and metals and local phase formation as well as the corrosion of heat exchanger material under a molten salt layer which is in contact with an outer gas phase. The general principles of the code development will be outlined while the details of the programs are given in separate presentations in this volume.

Gun Barrel Erosion—Comparison of Conventional and LOVA Gun Propellants

The research department Energetic Materials within TNO Defence, Security and Safety is involved in the development and (safety and insensitive munitions) testing of conventional (nitro cellulose based) and thermoplastic elastomer (TPE) based gun propellants. Recently our testing capabilities have been extended with vented vessel tests in order to investigate whether or not newly developed (low vulnerability (LOVA)) gun propellants or propellant formulations perform better in erosion tests. At the moment we have two vented vessel tests available, making it possible to determine the extent of erosion from a relatively low loading density to one comparable to a large caliber gun (maximum allowable pressures from 20 to 400MPa). Test pieces of various materials have been used and a number of LOVA and conventional gun propellants have been tested. From the results of these experiments the wear and wear rate have been determined. The erosion dependency on propellant properties like impetus, flame temperature, and combustion gas composition has been determined. Furthermore, an internal ballistics code has been adapted to model the pressure and temperature development in a vented vessel. The results are compared with the experimental results. This model will be described in short and the results presented.

小型2サイクルエンジンの掃気形状が燃焼状態に及ぼす影響の解析(機関特性と後処理,内燃機関の燃焼化学と排出物制御)

This paper presents the results of experiments conducted with a 2-cycle engine that was the world's first such engine to comply with the 2000 California emissions regulations for small off-road engine adopted by the U.S. state of California in 2000. This engine is fitted with two scavenging passage that runs around the crankcase and space of between piston and inside of the crankcase before the scavenging port. The aim of this research was to investigate how changes in the quantity of heat transferred to the fresh air as a result of varying the width of the scavenging passage would affect the state of combustion and exhaust gas composition. An ion prove was fitted to the center and end zone of the combustion chamber in order to detect the state of combustion.

Oxidation Restriction of In-flight Particles upon GS-HVOF Spraying by Nitrogen Addition to Combustion Gas

In order to improve the environmental barrier property of coatings fabricated by the HVOF spray process with a gas shroud, their oxygen content of 0.19 mass% as the lowest conventional figure was still more reduced by changing the composition of combustion gas. Introduction of nitrogen gas to the combustion chamber lowered the temperature of the in-flight spray particles while maintaining their high velocity. This method could reduce the oxygen level of a HastelloyC coating to 0.063 mass% at the lowest present value, which is comparable to that of the feedstock with 0.042 mass%. Other coating with 0.14 mass% could be obtained along with the open porosity below 0.1 vol%. The latter coating exhibited the improved environmental barrier property in artificial seawater.

Combustion and deposit formation behavior on the fireside surfaces of a pulverized fuel boiler fired with a blend of coal and petroleum coke

The thermochemistry of the combustion of a blend of coal and 5% petroleum coke was analyzed. Thermodynamic modeling and microscopic techniques were used to study the behavior of the inorganic constituents upon combustion of the blend of coal and petroleum coke. The chemical composition and phase constitution of the combustion products, as well as the deposits at several temperatures corresponding to those at the various parts of the boiler, were deduced by free-energy minimization. These results were compared with actual results obtained from a commercial pulverized fuel boiler fired with coal and petroleum coke blend. The deposits on the fireside surfaces of the boiler tubes in the various parts (water walls, platen superheater, final superheater, economizer, and electrostatic precipitator) of the commercial pulverized fuel boiler fired with coal and 5% petroleum coke were characterized by particle size analysis, chemical analysis, x-ray diffraction, optical microscopy, and scanning electron microscopy. The combustion gas composition was measured using a portable on-line gas analyzer for N 2 , O 2 , CO 2 , H 2 O, CO, NO, and SO 2 . The thermodynamically predicted compositions and phase constitutions for the gas phase as well as the condensed phases are in good agreement with the experimental results.

In-cylinder expansion of ring crevice hydrocarbons in SI engines

This paper presents the results of a theoretical study devoted to diffusion and removal of ring crevice HC's, compressed into the crevices during compression and partly combustion stroke. The model consists of three major submodels. First is prediction of time-varying composition of combustion gases, second is modelling the release of the ring crevice HC's during late expansion and exhaust stroke and the last one is a simple phenomenological approach for calculation of temperature variation with crank angle. Valve overlap period is excluded in the solution to be capable of assuming centrally located single valve for sake of adapting a 2D solution scheme. Flow field and HC concentrations are determined by solution of Navier-Stokes equations and equation of conservation of chemical species respectively. But instead of energy equation, above mentioned phenomenological submodel is introduced for calculation of temperature, despite the fact that it disturbs the nature of solution procedure of Navier-Stokes equations. Oil film HC's and postflame oxidation are excluded, as for the last, solution procedure enhances the period after which in cylinder oxidation ceases. Result are presented at the extend limited counterparts allow, due to the lack of common parameters adapted in different studies amongst plenty of them.

522 小型 2 サイクルエンジンの混合気加熱が燃焼状態に及ぼす影響の実験的研究

This paper presents the results of experiments conducted with a 2-cyle engine that was the world's first such engine to comply with the emissions regulations applied to small off-road engines by U.S. state of California in 2000. This engine is fitted with a scavenging passage that runs around the crankcase before the scavenging port. The aim of this research was to investigate how changes in the quantity of heat transferred to the fresh air as a result of varying the length of the scavenging passage would affect the state of combustion and exhaust gas composition. Two ion probes were fitted to the combustion chamber in order to detect the state of combustion.

405 低公害・小型 2 サイクルエンジンの実験的研究

This paper presents the results of experiments conducted with a 2-cycle engine that was the world's first such engine to comply with the 2000 California emissions regulations for small off-road engine adopted by the U.S state of in 2000. This engine is fitted with a scavenging passage that runs around the crankcase before the scavenging port. The aim of this research was to investigate how changes in the quantity of heat transferred to the fresh air as a result of varying the length of the scavenging passage would affect the state of combustion and exhaust gas composition.

Solid-phase microextraction method for gas chromatography with mass spectrometric and pulsed flame photometric detection: studies of organoarsenical speciation

The development, optimization, and application of a novel method for arsenic speciation based on capillary gas–liquid chromatography with simultaneous quadrupole ion-trap mass spectrometric (MS) detection and pulsed flame photometric detection (PFPD) is described. The method couples the sensitive arsenic-selectivity of PFPD with the structure elucidation capability of molecular MS detection for the determination of trace levels of unknown organoarsenicals in complex matrices. The conditions that affect the PFPD response in the presence of interfering species were optimized using the sequential Simplex algorithm for three key factors: gate delay (18.3 ms), gate width (9.1 ms), and combustion gas composition (16.6 ml/min H 2). Complete discrimination in the PFPD of the arsenic signal from interfering S-, C-, and OH-emitting species that are problematic in existing methods was achieved. Additionally, a revised interpretation of our previously reported mechanism [J. Chromatogr. A 807 (1998) 253] for the dithiol derivatization and subsequent GC–MS determination of dimethylarsinic acid is presented.

C213 マイクロアクチュエータ群による噴流拡散火炎の能動制御(オーガナイズドセッション6 : 自由噴流,衝突噴流およびはく離を伴う熱・物質移動)

A novel coaxial jet nozzle equipped with a row of miniature electromagnetic flap actuators was applied to active control of a methane-air diffusion flame. The flame and associated flow structures were studied through flow visualization, while the combustion gas composition at a postflame location was investigated by an FT-IR exhaust gas analyzer. The flap motion synchronized with a square-wave signal at the preferred mode frequency was found to be effective in stabilizing the lifted flame, because it provided a well-mixed fuel-air mixture at its flame base, achieving low NOx emission. On the other hand, a sawtooth-wave signal control stabilized the lifted flame dramatically, and led to low UHC emission with successive supply of large scale vortices at its flame base.

Performance of flammability of kerosene and NO x emission in the porous burner

The present study aims to develop the porous ceramic burner applicable to the Stirling engine, boilers and gas turbines using liquid fuels with the flammability in a large input load. As a liquid fuel, kerosene is supplied dropwise on the top surface of the porous ceramic plate and ignited on the bottom surface. The combustion behavior of the burner is examined by measuring the profiles of temperature and composition of combustion gas along the centerline in the chamber. The promotion effect of combustion is examined experimentally by installing a wire net at the chamber outlet. The boundary condition of the combustion changes substantially in the presence of the wire net. The behavior of NO x formation can be correlated by a function of the equilibrium NO concentration at a maximum temperature in the burner.

98/00489 CWS co-firing on two cyclone-fired electric utility boilers

This paper presents an investigation into combustion gas composition and deposit formation obtained by co-firing mixtures of cereal co-product (CCP) with a UK coal (Daw Mill) in a 100 kWth pilot-scale pulverised fuel (PF) combustion test rig operating at a feed rate of ∼7.5–11.2 kg/h. The biomass additions to the coal were at 0, 20, 40, 60, 80 and 100 wt.%. A high resolution multi-component Fourier Transform Infra-Red (FTIR) gas analyser was used to monitor the combustion gas stream for CO2, O2, H2O, SO2, CO, NO, NO2, N2O and HCl. It was observed that increasing the share of CCP in the fuel mixtures resulted in a reduction of SOx and HCl, due to the lower sulphur and chlorine contents of the biomass. Deposit formation in co-firing conditions was also studied on air-cooled probes (with surface temperatures of ∼500, 600 and 700 °C) to simulate the superheater/reheater surface conditions in a conventional pulverised fuel boiler. The deposition flux on the upsteam, sidestream and downstream of the probes were measured. The deposition flux on the upstream surfaces showed a decrease with an increasing biomass content in the fuel. Environmental scanning electron microscopy (ESEM) with energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD) were used to characterise the deposits. Chlorine was found in all three probes when the CCP was fired without any coal addition, suggesting formation of alkali chlorides through condensation on cooler surfaces (also confirmed by XRD analysis). The study highlights the complex relationship between the fuel mixtures and compositions of the combustion gas streams, as well as deposition fluxes and deposit compositions.

98/00490 Determination of the operational parameters of steam generation in coal-fired power stations

This paper presents an investigation into combustion gas composition and deposit formation obtained by co-firing mixtures of cereal co-product (CCP) with a UK coal (Daw Mill) in a 100 kWth pilot-scale pulverised fuel (PF) combustion test rig operating at a feed rate of ∼7.5–11.2 kg/h. The biomass additions to the coal were at 0, 20, 40, 60, 80 and 100 wt.%. A high resolution multi-component Fourier Transform Infra-Red (FTIR) gas analyser was used to monitor the combustion gas stream for CO2, O2, H2O, SO2, CO, NO, NO2, N2O and HCl. It was observed that increasing the share of CCP in the fuel mixtures resulted in a reduction of SOx and HCl, due to the lower sulphur and chlorine contents of the biomass. Deposit formation in co-firing conditions was also studied on air-cooled probes (with surface temperatures of ∼500, 600 and 700 °C) to simulate the superheater/reheater surface conditions in a conventional pulverised fuel boiler. The deposition flux on the upsteam, sidestream and downstream of the probes were measured. The deposition flux on the upstream surfaces showed a decrease with an increasing biomass content in the fuel. Environmental scanning electron microscopy (ESEM) with energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD) were used to characterise the deposits. Chlorine was found in all three probes when the CCP was fired without any coal addition, suggesting formation of alkali chlorides through condensation on cooler surfaces (also confirmed by XRD analysis). The study highlights the complex relationship between the fuel mixtures and compositions of the combustion gas streams, as well as deposition fluxes and deposit compositions.

97/04252 Correction of the composition of combustion gases by Ostwalds method without drawing of a control diagram

97/04252 Correction of the composition of combustion gases by Ostwalds method without drawing of a control diagram

Performance of numerical spray combustion simulation

The aim of this study is to examine the performance of numerical spray combustion simulation. A numerical simulation for the prediction of local properties of heavy oil spray flames stabilized by a baffle plate is described. Time-averaged governing conservation equations are solved to estimate the combustion gas flow, gas composition and temperature fields in the experimental combustor. The κ-ε turbulence model is used to describe the turbulent flow field. The behavior of fuel droplets in the turbulent combustion gas flow is calculated by the Lagrangian method. The combustion rate of fuel vapor is estimated by the eddy dissipation model. The effects of radiation are accounted for by the six-flux model of radiation. The performance of the simulation is examined by comparison with measured data. In the isothermal (cold) case, the calculated flow pattern is compared with the data measured by LDA, and it is clear that the calculated results show quantitative agreement with the measured data. In the combustion case, however, the simulation cannot predict well the measured profiles of temperature, O 2 and CO 2 concentrations near the baffle plate. It is inferred that this simulation cannot estimate accurately the interaction between the recirculation flow induced by the baffle plate and fuel droplets.

SO2 and NOx Removal from Combustion Flue Gas by Corona Discharge in Laboratory-Scale Experiment.

It has been reported that SO2 and NOx in flue gas can be removed by corona discharge and that pulsed corona discharge is as energy-efficient as electron-beam treatment. A large amount of data is required, however, to assess the industrial application of the corona discharge method to the removal of SO2 and NOx from combustion flue gas. In this study experiments of SO2 and NOx removal from actual and simulated combustion gas have been performed on a laboratory scale, where combustion gas composition, temperature, residence time in the discharge duct, and the polarity of high-voltage electrodes are changed for DC and pulsed corona discharge. The following experimental results are obtained: (1) the increase in H2O and O2 concentration improves SO2 and NOx removal rate, (2) dendritic (NH4)2SO4 powders tend to deposit on high-voltage electrodes, and (3) the electrode polarity has a nominal effect on the removal rate under our experimental conditions.

Change of characteristics of desulfurization and denitrification by combustion flue gas composition and electrode configuration under pulsed corona discharge

AbstractLaboratory‐scale and parametric experiments of SO2 and NOx removal from the simulated combustion gas by pulsed corona discharge have been performed by changing the combustion gas composition and temperature, the electrode configuration of plasma reactor, and the polarity of high‐voltage electrode. The following results are obtained: 1) the higher the concentration of H2O and O2, the higher the efficiency of desulfurization and denitrification at the same specific input; 2) the pulsed corona discharge with a voltage pulsewidth as short as 200 ns of negative polarity shows the possibility to attain almost 90 percent deSOx and deNOx efficiency at the specific discharge input of 20 J/g, which is almost the same as the specific input in the electron‐beam process; 3) the deNOx characteristics show a little temperature dependence in the range of 70 to 130°C, but the deSOx efficiency increases rapidly in the temperature region below 100°C suggesting the thermochemical dependence of deSOx reaction; 4) when desulfurization and denitrification proceed, the white dendritic powder deposits on the plasma reactor whose composition is identified to be 49 mol% (NH4)2SO4 and 47 mol% of 2NH4NO3 · (NH4)2SO4, and the ratio of SO2, NO and NH3 of the deposit is almost equal to that of supplied gas.

Characteristics Change of Desulfurization and Denitrification by Combustion Flue Gas Composition and Electrode Configuration under Pulsed Corona Discharge.

Laboratory-scale and parametric experiments of SO2, and NOx, removal from the simulated combustion gas by pulsed corona discharge have been performed changing the combustion gas composition and temperature, the electrode configuration of plasma reactor and the polarity of high-voltage electrode. The following results are obtained, 1) the higher the concentration of H2O and O2, the higher the efficiency of desulfurization and denitrification at the same specific input, 2) the pulsed corona discharge with a voltage pulse-width as short as 200 ns of negative polarity shows the possibility to attain almost 90% deSOx and de NOx efficiency at the specific discharge input of 20 J/g, which is almost the same as the specific input in the electron-beam process, 3) the de NOx characteristics shows a little temperature dependence in the range of 70_??_130°C, but the de SOx efficiency increases rapidly in the temperature region below 100°C suggesting the thermochemical dependence of deSOx reaction, 4) when desulfurization and denitrification proceed, the white dendritic powder deposits on the plasma reactor which composition is identified to be 49 mol % of (NH4)2SO4 and 47 mol % of 2NH4NO3 • (NH4)2SO4, and the ratio of SO2, NO and NH3 of the deposit is almost equal to that of supplied gas.

SO2 and NOx Removal from Combustion Flue Gas by Corona Discharge in Laboratory Scale Experiment.

It is reported that SO2 and NOx in a flue gas can be removed by corona discharge and that pulse corona discharge is as energy-efficient as the electron-beam treatment. However a large amount of data are required to assess the industrial application of the corona discharge method to remove SO2 and NOx from combustion flue gas. In this study parametric experiments of SO2 and NOx removal from actual and simulated combustion gas have been performed on a laboratory scale, where combustion gas composition, temperature, residence time in a discharge duct and the polarity of high voltage electrode are changed for DC and pulsed corona discharge. The following experimental results are obtained : (1) the increase in H2O and O2 concentration improves the SO2 and NOx removal performance, (2) dendritic powders of (NH4)2SO4 are apt to deposit on a high-voltage electrode, and (3) the electrode polarity has a nominal effect on the removal performance under our experimental conditions.